WorldWideScience

Sample records for annular dark-field stem

  1. Atomic-resolution incoherent high-angle annular dark field STEM images of Si(011)

    Science.gov (United States)

    Watanabe, K.; Yamazaki, T.; Kikuchi, Y.; Kotaka, Y.; Kawasaki, M.; Hashimoto, I.; Shiojiri, M.

    2001-02-01

    Characteristic atomic-resolution incoherent high-angle annular dark field (HAADF) scanning transmission electron microscope (STEM) images of [011]-orientated Si have been experimentally obtained by a through-focal series. Artificial bright spots appear at positions where no atomic columns exist along the electron beam, in some experimental images. Image simulation, based on the Bloch wave description by the Bethe method, reproduces the through-focal experimental images. It is shown that atomic-resolution HAADF STEM images, which are greatly influenced by the Bloch wave field depending on the incident electron beam probe, cannot always be interpreted intuitively as the projected atomic images. It is also found that the atomic-resolution HAADF STEM images can be simply explained using the relations to the probe functions without the need for complex dynamical simulations.

  2. Annular bright and dark field imaging of soft materials

    International Nuclear Information System (INIS)

    Here polyethylene, as an example of an important soft material, was studied by STEM annular bright and dark field. The contrast as function of the probe size/shape and the detector collection angle are discussed. The results are compared to conventional bright field transmission electron microscopy, electron energy filtered imaging and energy dispersive spectroscopy mapping. Annular bright and dark field gave a higher contrast than conventional transmission and analytical mapping techniques

  3. 3D strain measurement in electronic devices using through-focal annular dark-field imaging

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Suhyun; Jung, Younheum; Lee, Sungho; Jung Kim, Joong; Byun, Gwangseon; Lee, Sunyoung; Lee, Haebum

    2014-11-15

    Spherical aberration correction in high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) allows us to form an electron probe with reduced depth of field. Using through-focal HAADF imaging, we experimentally demonstrated 3D strain measurement in a strained-channel transistor. The strain field distribution in the channel region was obtained by scanning an electron beam over a plan-view specimen. Furthermore, the decrease in the strain fields toward the silicon substrate was revealed at different focal planes with a 5-nm focal step. These results demonstrate that it is possible to reconstruct the 3D strain field in electronic devices. - Highlights: • Three dimensional strain fields were measured using through-focal HAADF-STEM series. • The technique was applied to the channel of a plan-view strained-silicon device. • The strain values agreed with the results obtained using cross-section specimen.

  4. Experimental quantification of annular dark-field images in scanning transmission electron microscopy.

    Science.gov (United States)

    Lebeau, James M; Stemmer, Susanne

    2008-11-01

    This paper reports on a method to obtain atomic resolution Z-contrast (high-angle annular dark-field) images with intensities normalized to the incident beam. The procedure bypasses the built-in signal processing hardware of the microscope to obtain the large dynamic range necessary for consecutive measurements of the incident beam and the intensities in the Z-contrast image. The method is also used to characterize the response of the annular dark-field detector output, including conditions that avoid saturation and result in a linear relationship between the electron flux reaching the detector and its output. We also characterize the uniformity of the detector response across its entire area and determine its size and shape, which are needed as input for image simulations. We present normalized intensity images of a SrTiO(3) single crystal as a function of thickness. Averaged, normalized atom column intensities and the background intensity are extracted from these images. The results from the approach developed here can be used for direct, quantitative comparisons with image simulations without any need for scaling. PMID:18707809

  5. Dose limited reliability of quantitative annular dark field scanning transmission electron microscopy for nano-particle atom-counting

    Energy Technology Data Exchange (ETDEWEB)

    De Backer, A.; Martinez, G.T. [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); MacArthur, K.E.; Jones, L. [Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH (United Kingdom); Béché, A. [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium); Nellist, P.D. [Department of Materials, University of Oxford, 16 Parks Road, Oxford OX1 3PH (United Kingdom); Van Aert, S., E-mail: sandra.vanaert@uantwerpen.be [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, B-2020 Antwerp (Belgium)

    2015-04-15

    Quantitative annular dark field scanning transmission electron microscopy (ADF STEM) has become a powerful technique to characterise nano-particles on an atomic scale. Because of their limited size and beam sensitivity, the atomic structure of such particles may become extremely challenging to determine. Therefore keeping the incoming electron dose to a minimum is important. However, this may reduce the reliability of quantitative ADF STEM which will here be demonstrated for nano-particle atom-counting. Based on experimental ADF STEM images of a real industrial catalyst, we discuss the limits for counting the number of atoms in a projected atomic column with single atom sensitivity. We diagnose these limits by combining a thorough statistical method and detailed image simulations. - Highlights: • Limited size and beam sensitivity of nano-particles challenge their quantification. • Keeping the electron dose to a minimum is therefore important. • Reliability of quantitative ADF STEM for atom-counting is demonstrated. • Limits for single atom sensitivity are discussed. • Limits are diagnosed by combining simulations and a statistical method.

  6. Direct imaging of light elements by annular dark-field aberration-corrected scanning transmission electron microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lotnyk, Andriy, E-mail: andriy.lotnyk@iom-leipzig.de; Poppitz, David; Gerlach, Jürgen W.; Rauschenbach, Bernd [Leibniz Institute of Surface Modification, Permoserstr. 15, D-04318 Leipzig (Germany)

    2014-02-17

    In this report, we show that an annular dark-field detector in an aberration-corrected scanning transmission electron microscope allows the direct observation of light element columns in crystalline lattices. At specific imaging conditions, an enhancement of the intensities of light element columns in the presence of heavy element columns is observed. Experimental results are presented for imaging the nitrogen and carbon atomic columns at the GaN-SiC interface and within the GaN and SiC compounds. The crystal polarity of GaN at the interface is identified. The obtained findings are discussed and are well supported by image simulations.

  7. Measurement of indium concentration profiles and segregation efficiencies from high-angle annular dark field-scanning transmission electron microscopy images

    International Nuclear Information System (INIS)

    We investigated segregation of indium in an InxGa1−xAs/GaAs heterostructure via high-angle annular dark field-scanning transmission electron microscopy (HAADF-STEM), where contrast strongly depends on the nuclear charges of the scattering atoms (Z-contrast). Indium concentration maps have been deduced from HAADF-STEM images by comparing normalized measured intensities with multislice simulations in the frozen lattice approach. Segregation coefficients were derived following the segregation model of Muraki et al. [1]. This is demonstrated for HAADF-STEM images recorded in [100] and [110] zone-axes. Determined indium concentrations and segregation coefficients are compared with results from composition analysis by lattice fringe analysis (CELFA) measurements and energy-dispersive X-ray analysis (EDX). - Highlights: • We measured the indium concentration in an InGaAs/GaAs heterostructure by HAADF-STEM. • Multislice calculations are carried out for [100] and [110] electron beam direction. • [110] beam direction is better suited for concentration analysis. • Segregation efficiencies are derived from concentration profiles. • HAADF-STEM results are compared to CELFA measurement

  8. Intergrowth structure of α-phase in β-type TmAlB4 compound studied by high-angle annular detector dark-field scanning transmission electron microscopy

    International Nuclear Information System (INIS)

    Nanostructure of a ThMoB4-type (β-type) TmAlB4 compound, in which YCrB4-type (α-type) domains are locally intergrown, is studied by high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). Z-contrast images by HAADF-STEM directly represent the arrangements of Tm atoms located at centers of heptagonal atomic columns of B atoms as bright dots, and give us detailed information of intergrowth of type domains in the matrix of the β-type phase, which coherently occurs. Structural and bonding analyses for β-TmAlB4 point out the closeness in atomic interactions and energy of the α- and β-type structures which support the easy formation of such nanostructure intergrowths. From combination between HAADF-STEM and electronic structure calculation, a detailed local crystal structure with intrinsic building defects is effectively revealed. - Graphical abstract: Nanostructure of a ThMoB4-type (β-type) TmAlB4 compound, in which YCrB4-type (α-type) domains are locally intergrown, is studied by high-angle annular detector dark-field scanning transmission electron microscopy (HAADF-STEM). Z-contrast images by HAADF-STEM directly represent arrangements of Tm atoms located at centers of heptagonal atomic columns of B atoms as bright dots, and give us detailed information of the characteristic intergrowth structure of type domains in the matrix of the β-type phase. - Highlights: • HAADF-STEM images directly represent arrangements of Tm atoms as bright dots. • The α-type planar domains coherently intergrown in the β-type matrix. • Bright strips appear at overlapped regions of Tm hexagons along interfaces between α- and β-type domains

  9. Boron concentration profiling by high angle annular dark field-scanning transmission electron microscopy in homoepitaxial δ-doped diamond layers

    Energy Technology Data Exchange (ETDEWEB)

    Araújo, D.; Alegre, M. P.; Piñero, J. C. [Dpto Ciencia de los Materiales, Facultad de Ciencias, Universidad de Cádiz, 11510 Puerto Real (Cádiz) (Spain); Fiori, A.; Bustarret, E. [Institut Néel, CNRS-Université Joseph Fourier, 25 av. des Martyrs, 38042 Grenoble (France); Jomard, F. [Groupe d' Etude de la Matière Condensée (GEMaC), UMR 8635 du CNRS, UVSQ, 45 av. des Etats-Unis, 78035 Versailles Cedex (France)

    2013-07-22

    To develop further diamond related devices, the concentration and spatial location of dopants should be controlled down to the nanometer scale. Scanning transmission electron microscopy using the high angle annular dark field mode is shown to be sensitive to boron doping in diamond epilayers. An analytical procedure is described, whereby local boron concentrations above 10{sup 20} cm{sup −3} were quantitatively derived down to nanometer resolution from the signal dependence on thickness and boron content. Experimental boron local doping profiles measured on diamond p{sup −}/p{sup ++}/p{sup −} multilayers are compared to macroscopic profiles obtained by secondary ion mass spectrometry, avoiding reported artefacts.

  10. Monte Carlo electron-trajectory simulations in bright-field and dark-field STEM: Implications for tomography of thick biological sections

    Energy Technology Data Exchange (ETDEWEB)

    Sousa, A.A.; Hohmann-Marriott, M.F.; Zhang, G. [Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bldg. 13, Rm. 3N17, 13 South Drive, Bethesda, MD 20892-5766 (United States); Leapman, R.D. [Laboratory of Bioengineering and Physical Science, National Institute of Biomedical Imaging and Bioengineering, National Institutes of Health, Bldg. 13, Rm. 3N17, 13 South Drive, Bethesda, MD 20892-5766 (United States)], E-mail: leapmanr@mail.nih.gov

    2009-02-15

    A Monte Carlo electron-trajectory calculation has been implemented to assess the optimal detector configuration for scanning transmission electron microscopy (STEM) tomography of thick biological sections. By modeling specimens containing 2 and 3 at% osmium in a carbon matrix, it was found that for 1-{mu}m-thick samples the bright-field (BF) and annular dark-field (ADF) signals give similar contrast and signal-to-noise ratio provided the ADF inner angle and BF outer angle are chosen optimally. Spatial resolution in STEM imaging of thick sections is compromised by multiple elastic scattering which results in a spread of scattering angles and thus a spread in lateral distances of the electrons leaving the bottom surface. However, the simulations reveal that a large fraction of these multiply scattered electrons are excluded from the BF detector, which results in higher spatial resolution in BF than in high-angle ADF images for objects situated towards the bottom of the sample. The calculations imply that STEM electron tomography of thick sections should be performed using a BF rather than an ADF detector. This advantage was verified by recording simultaneous BF and high-angle ADF STEM tomographic tilt series from a stained 600-nm-thick section of C. elegans. It was found that loss of spatial resolution occurred markedly at the bottom surface of the specimen in the ADF STEM but significantly less in the BF STEM tomographic reconstruction. Our results indicate that it might be feasible to use BF STEM tomography to determine the 3D structure of whole eukaryotic microorganisms prepared by freeze-substitution, embedding, and sectioning.

  11. Dark field electron holography for strain measurement

    Energy Technology Data Exchange (ETDEWEB)

    Beche, A., E-mail: armand.beche@fei.com [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Rouviere, J.L. [CEA-Grenoble, INAC/SP2M/LEMMA, F-38054 Grenoble (France); Barnes, J.P.; Cooper, D. [CEA-LETI, Minatec Campus, F-38054 Grenoble (France)

    2011-02-15

    Dark field electron holography is a new TEM-based technique for measuring strain with nanometer scale resolution. Here we present the procedure to align a transmission electron microscope and obtain dark field holograms as well as the theoretical background necessary to reconstruct strain maps from holograms. A series of experimental parameters such as biprism voltage, sample thickness, exposure time, tilt angle and choice of diffracted beam are then investigated on a silicon-germanium layer epitaxially embedded in a silicon matrix in order to obtain optimal dark field holograms over a large field of view with good spatial resolution and strain sensitivity. -- Research Highlights: {yields} Step by step explanation of the dark field electron holography technique. {yields} Presentation of the theoretical equations to obtain quantitative strain map. {yields} Description of experimental parameters influencing dark field holography results. {yields} Quantitative strain measurement on a SiGe layer embedded in a silicon matrix.

  12. Dark-field optical coherence microscopy

    OpenAIRE

    Villiger, Martin; Pache, Christophe; Lasser, Theo

    2010-01-01

    Dark-field illumination is known to enhance scattering contrast in optical microscopy. We combined this concept with Fourier domain optical coherence microscopy (OCM). The detection and illumination paths are decoupled, and only the scattered light originating from the sample generates the tomogram signal, whereas any specular reflection is highly suppressed. We analyze and discuss this dark-field OCM concept and present its superior imaging quality on live cell samples. (C) 2010 Optical Soci...

  13. Sidestream dark field images of the microcirculation

    DEFF Research Database (Denmark)

    Petersen, Sandra M; Greisen, Gorm; Hyttel-Sorensen, Simon;

    2014-01-01

    BACKGROUND: Since analysis of Sidestream Dark Field images still requires subjective interpretation, we wanted to determine intra-observer repeatability and to estimate the correlation between different evaluation methods. METHODS: Fifty-four Sidestream Dark Field videos were analyzed twice......) the "Boerma" method, generating a Microvascular Flow Index (MFI) by quadrants. RESULTS: Intraclass Correlation Coefficients (ICCs) were above 0.9 for TVD and above 0.8 for PDV and PPV. MFIby quadrants had the lowest reliability (ICC = 0.52 for capillaries and ICC = 0.59 for all vessels), significantly lower.......64) for capillaries and 1.01 (0.85 - 1.16) for all vessels. CONCLUSIONS: Intra-observer reliability for full evaluation of Sidestream Dark Field images was good for vessel detection and for flow classification but significantly poorer for the faster "Boerma" method. Furthermore, the Boerma method is likely...

  14. Dark Field Microscopy for Analytical Laboratory Courses

    Science.gov (United States)

    Augspurger, Ashley E.; Stender, Anthony S.; Marchuk, Kyle; Greenbowe, Thomas J.; Fang, Ning

    2014-01-01

    An innovative and inexpensive optical microscopy experiment for a quantitative analysis or an instrumental analysis chemistry course is described. The students have hands-on experience with a dark field microscope and investigate the wavelength dependence of localized surface plasmon resonance in gold and silver nanoparticles. Students also…

  15. Annular pancreas

    Science.gov (United States)

    ... page: //medlineplus.gov/ency/article/001142.htm Annular pancreas To use the sharing features on this page, please enable JavaScript. An annular pancreas is a ring of pancreatic tissue that encircles ...

  16. Cutaneous microcirculation in preterm neonates: comparison between sidestream dark field (SDF) and incident dark field (IDF) imaging

    NARCIS (Netherlands)

    H. van Elteren (Hugo); C. Ince (Can); D. Tibboel (Dick); I.K.M. Reiss (Irwin); R.C.J. De Jonge (Rogier C. J.)

    2015-01-01

    textabstractIncident dark field imaging (IDF) is a new generation handheld microscope for bedside visualization and quantification of microcirculatory alterations. IDF is the technical successor of sidestream dark field imaging (SDF), currently the most used device for microcirculatory measurements.

  17. Mapping misoriented fibers using X-ray dark field tomography

    DEFF Research Database (Denmark)

    Lauridsen, Torsten; Lauridsen, Erik Mejdal; Feidenhans’l, Robert

    2014-01-01

    X-ray grating interferometers produce three distinct signals; an absorption signal, a differential phase signal and a dark field signal. Until now a method for successfully creating dark field tomograms of nonisotropic samples has not been demonstrated. In this paper we test a method for creating.......e. a horizontal rotation axis in most setup configurations) it is possible to produce a darkfield tomogram where fibers parallel to the probed scattering direction appear to have no dark field signal. The method produces a tomogram in the form of a scalar field of dark field scattering values....

  18. Dark-Field Scanning Transmission Ion Microscopy via Detection of Forward-Scattered Helium Ions with a Microchannel Plate.

    Science.gov (United States)

    Woehl, Taylor J; White, Ryan M; Keller, Robert R

    2016-06-01

    A microchannel plate was used as an ion sensitive detector in a commercial helium ion microscope (HIM) for dark-field transmission imaging of nanomaterials, i.e. scanning transmission ion microscopy (STIM). In contrast to previous transmission HIM approaches that used secondary electron conversion holders, our new approach detects forward-scattered helium ions on a dedicated annular shaped ion sensitive detector. Minimum collection angles between 125 mrad and 325 mrad were obtained by varying the distance of the sample from the microchannel plate detector during imaging. Monte Carlo simulations were used to predict detector angular ranges at which dark-field images with atomic number contrast could be obtained. We demonstrate atomic number contrast imaging via scanning transmission ion imaging of silica-coated gold nanoparticles and magnetite nanoparticles. Although the resolution of STIM is known to be degraded by beam broadening in the substrate, we imaged magnetite nanoparticles with high contrast on a relatively thick silicon nitride substrate. We expect this new approach to annular dark-field STIM will open avenues for more quantitative ion imaging techniques and advance fundamental understanding of underlying ion scattering mechanisms leading to image formation. PMID:27153003

  19. Dark-Field Scanning Transmission Ion Microscopy via Detection of Forward-Scattered Helium Ions with a Microchannel Plate.

    Science.gov (United States)

    Woehl, Taylor J; White, Ryan M; Keller, Robert R

    2016-06-01

    A microchannel plate was used as an ion sensitive detector in a commercial helium ion microscope (HIM) for dark-field transmission imaging of nanomaterials, i.e. scanning transmission ion microscopy (STIM). In contrast to previous transmission HIM approaches that used secondary electron conversion holders, our new approach detects forward-scattered helium ions on a dedicated annular shaped ion sensitive detector. Minimum collection angles between 125 mrad and 325 mrad were obtained by varying the distance of the sample from the microchannel plate detector during imaging. Monte Carlo simulations were used to predict detector angular ranges at which dark-field images with atomic number contrast could be obtained. We demonstrate atomic number contrast imaging via scanning transmission ion imaging of silica-coated gold nanoparticles and magnetite nanoparticles. Although the resolution of STIM is known to be degraded by beam broadening in the substrate, we imaged magnetite nanoparticles with high contrast on a relatively thick silicon nitride substrate. We expect this new approach to annular dark-field STIM will open avenues for more quantitative ion imaging techniques and advance fundamental understanding of underlying ion scattering mechanisms leading to image formation.

  20. Dark field X-ray microscopy for studies of recrystallization

    DEFF Research Database (Denmark)

    Ahl, Sonja Rosenlund; Simons, Hugh; Jakobsen, Anders Clemen;

    2015-01-01

    We present the recently developed technique of Dark Field X-Ray Microscopy that utilizes the diffraction of hard X-rays from individual grains or subgrains at the (sub)micrometre- scale embedded within mm-sized samples. By magnifying the diffracted signal, 3D mapping of orientations and strains...... external influences. The capabilities of Dark Field X- Ray Microscopy are illustrated by examples from an ongoing study of recrystallization of 50% cold-rolled Al1050 specimens....

  1. Energy weighted x-ray dark-field imaging

    CERN Document Server

    Pelzer, Georg; Anton, Gisela; Bayer, Florian; Horn, Florian; Kraus, Manuel; Rieger, Jens; Ritter, Andre; Wandner, Johannes; Weber, Thomas; Fauler, Alex; Fiederle, Michael; Wong, Winnie S; Campbell, Michael; Meiser, Jan; Meyer, Pascal; Mohr, Jürgen; Michel, Thilo

    2014-01-01

    The dark-field image obtained in grating-based x-ray phase-contrast imaging can provide information about the objects' microstructures on a scale smaller than the pixel size even with low geometric magnification. In this publication we demonstrate that the dark-field image quality can be enhanced with an energy-resolving pixel detector. Energy-resolved x-ray dark-field images were acquired with a 16-energy-channel photon-counting pixel detector with a 1 mm thick CdTe sensor in a Talbot-Lau x-ray interferometer. A method for contrast-noise-ratio (CNR) enhancement is proposed and validated experimentally. In measurements, a CNR improvement by a factor of 1.14 was obtained. This is equivalent to a possible radiation dose reduction of 23%.

  2. [Granuloma annulare].

    Science.gov (United States)

    Butsch, F; Weidenthaler-Barth, B; von Stebut, E

    2015-11-01

    Granuloma annulare is a benign, chronic inflammatory skin disease. Its pathogenesis is still unclear, but reports on infections as a trigger can be found. In addition, some authors reported an association with other systemic disease, e.g., cancer, trauma, and diabetes mellitus; however, these have not been verified. The clinical picture of granuloma annulare ranges from the localized form predominantly at the extremities to disseminated, subcutaneous, or perforating forms. Diagnosis is based on the typical clinical presentation which may be confirmed by a biopsy. Histologically, necrobiotic areas within granulomatous inflammation are typical. The prognosis of the disease is good with spontaneous resolution being frequently observed, especially in localized forms. Disseminated manifestations tend to persist longer, and recurrences are reported. When choosing between different therapeutic options, the benign disease character versus the individual degree of suffering and the potential therapy side effects must be considered. For local treatment, topical application of corticosteroids is most common. Disseminated forms can be treated systemically with corticosteroids for several weeks; alternatively, dapsone, hydroxychloroquine, retinoids, fumaric acid, cyclosporine, and anti-TNFα appear to be effective. PMID:26487494

  3. Analyzing Microchips With Dark-Field Negative Photomicrography

    Science.gov (United States)

    Suszko, S. F.

    1985-01-01

    Inverse development process yields fine details. Photomicrographic technique produces images of integrated-circuit chips. Technique based on dark-field illumination: (chip lit with bright central spot of light and photographed by light scattered or diffracted from spot. Reveals more about microstructure patterns related to photoresist masking than more conventional bright-field method.

  4. A comparison of the quality of image acquisition between the incident dark field and sidestream dark field video-microscopes

    NARCIS (Netherlands)

    E. Gilbert-Kawai; J. Coppel (Jonny); V. Bountziouka (Vassiliki); C. Ince (Can); D. Martin (Daniel)

    2016-01-01

    textabstractBackground The ‘Cytocam’ is a third generation video-microscope, which enables real time visualisation of the in vivo microcirculation. Based upon the principle of incident dark field (IDF) illumination, this hand held computer-controlled device was designed to address the technical lim

  5. Plasmonic dark field microscopy with a polymer substrate

    CERN Document Server

    Chen, Yikai; Han, Lu; Wang, Xiangxian; Zhu, Liangfu; Wang, Pei; Ming, Hai

    2013-01-01

    In this letter, a plasmonic dark field microscopy taking advantages of the polymer loaded surface plasmon polariton waveguide (PLSPPW) is experimentally demonstrated. The dye molecules (Rhodamine 6G, Rh6G) are doped in the PLSPPW to launch the plasmonic waves or guided waves. Due to the localized property of these waves, the near-field optical energy on the surface of PLSPPW can be scattered into the far-field only in the presence of the objects. The scattering signals then form the dark-field image of the objects. The proposed technique just utilizes a chip-scale integrated plasmonic multilayered structure which is highly compatible with the conventional optical microscopy. The polymer film involved in the PLSPPW also brings about the merits of small roughness, good stability and bio-compatibility

  6. STEM tomography for thick biological specimens

    Energy Technology Data Exchange (ETDEWEB)

    Aoyama, Kazuhiro [FEI Company Japan Ltd., Application Laboratory, NSS-II Building, 2-13-34 Kohnan, Minato-ku, Tokyo 108-0075 (Japan)], E-mail: kazuhiro.aoyama@fei.com; Takagi, Tomoko [FEI Company Japan Ltd., Application Laboratory, NSS-II Building, 2-13-34 Kohnan, Minato-ku, Tokyo 108-0075 (Japan); Laboratory of Electron Microscopy, Japan Women' s University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo 112-8681 (Japan); Hirase, Ai; Miyazawa, Atsuo [Bio-multisome Research Team, RIKEN SPring-8 Center, Harima Institute, 1-1-1 Kouto, Sayo, Hyogo 679-5148 (Japan); CREST, JST (Japan)

    2008-12-15

    Scanning transmission electron microscopy (STEM) tomography was applied to biological specimens such as yeast cells, HEK293 cells and primary culture neurons. These cells, which were embedded in a resin, were cut into 1-{mu}m-thick sections. STEM tomography offers several important advantages including: (1) it is effective even for thick specimens, (2) 'dynamic focusing', (3) ease of using an annular dark field (ADF) mode and (4) linear contrasts. It has become evident that STEM tomography offers significant advantages for the observation of thick specimens. By employing STEM tomography, even a 1-{mu}m-thick specimen (which is difficult to observe by conventional transmission electron microscopy (TEM)) was successfully analyzed in three dimensions. The specimen was tilted up to 73 deg. during data acquisition. At a large tilt angle, the specimen thicknesses increase dramatically. In order to observe such thick specimens, we introduced a special small condenser aperture that reduces the collection angle of the STEM probe. The specimen damage caused by the convergent electron beam was expected to be the most serious problem; however, the damage in STEM was actually smaller than that in TEM. In this study, the irradiation damage caused by TEM- and STEM-tomography in biological specimens was quantitatively compared.

  7. Aberration corrected STEM of iron rhodium nanoislands

    Science.gov (United States)

    McLaren, M. J.; Hage, F. S.; Loving, M.; Ramasse, Q. M.; Lewis, L. H.; Marrows, C. H.; Brydson, R. M. D.

    2014-06-01

    Iron-rhodium (FeRh) nanoislands of equiatomic composition have been analysed using scanning transmission electron microscopy (STEM) electron energy loss spec-troscopy(EELS) and high angle annular dark field (HAADF) techniques. Previous magne-tometry results have lead to a hypothesis that at room temperature the core of the islands are antiferromagnetic while the shell has a small ferromagnetic signal. The causes of this effect are most likely to be a difference in composition at the edges or a strain on the island that stretches the lattice and forces the ferromagnetic transition. The results find, at the film-substrate interface, an iron-rich layer ~ 5 Å thick that could play a key role in affecting the magnetostructural transition around the interfacial region and account for the room temperature ferromagnetism.

  8. Annular Flow Distribution test

    International Nuclear Information System (INIS)

    This report documents the Babcock and Wilcox (B ampersand W) Annular Flow Distribution testing for the Savannah River Laboratory (SRL). The objective of the Annular Flow Distribution Test Program is to characterize the flow distribution between annular coolant channels for the Mark-22 fuel assembly with the bottom fitting insert (BFI) in place. Flow rate measurements for each annular channel were obtained by establishing ''hydraulic similarity'' between an instrumented fuel assembly with the BFI removed and a ''reference'' fuel assembly with the BFI installed. Empirical correlations of annular flow rates were generated for a range of boundary conditions

  9. Study of Porous Materials Acoustic Signatures Behaviour in Dark Field

    Energy Technology Data Exchange (ETDEWEB)

    Bouhedja, S; Hamdi, F [Laboratoires des Hyperfrequences et Semi-conducteurs, Universite de Constantine, B.P. 125, DZ-25000 (Algeria); Doghmane, A; Hadjoub, Z, E-mail: bouhedja_samia@yahoo.fr, E-mail: a_doghmane@yahoo.fr [Laboratoire des Semi-Conducteurs, Departement de Physique, Faculte des Sciences, Universite Badji-Mokhtar, BP 12, Annaba, DZ-23000 (Algeria)

    2011-03-01

    Several kinds of lens-transducer system exist in the scanning acoustic microscope. In this work, annular lenses are chosen in order to quantify the occultation limiting angle to suppress Rayleigh mode generation. Hence, we have numerically simulated, through variable occultation of generated rays at the lens center, the porous silicon acoustic signatures at an operating frequency of 142 MHz. In non destructive control, this investigation is of a great importance in the measurement of the surface waves attenuation. The obtained results enabled us to evaluate the maximum relative occultation at Rayleigh waves.

  10. Hyperspectral Dark Field Optical Microscopy of Single Silver Nanospheres

    Energy Technology Data Exchange (ETDEWEB)

    El-Khoury, Patrick Z.; Joly, Alan G.; Hess, Wayne P.

    2016-04-07

    We record spectrally (400 nm ≤ λ ≤ 675 nm, Δλ < 4.69 nm) and spatially (diffraction-limited, sampled at 85 nm2/pixel) resolved dark field (DF) scattering from single silver nanospheres of 100 nm in diameter. Hyperspectral DF optical microscopy is achieved by coupling a hyperspectral detector to an optical microscope, whereby spectrally resolved diffraction-limited images of hundreds of silver nanoparticles can be recorded in ~30 seconds. We demonstrate how the centers and edges of individual particles can be localized in 2D to within a single pixel (85 nm2), using a statistical method for examining texture based on a co-occurrence matrix. Subsequently, spatial averaging of the spectral response in a 3x3 pixel area around the particle centers affords ample signal-to-noise to resolve the plasmon resonance of a single silver nanosphere. A close inspection of the scattering spectra of 31 different nanospheres reveals that each particle has its unique (i) relative scattering efficiency, and (ii) plasmon resonance maximum and dephasing time. These observations are suggestive of nanometric structural variations over length scales much finer than the spatial resolution attainable using the all-optical technique described herein.

  11. Subcutaneous granuloma annulare

    Directory of Open Access Journals (Sweden)

    Dhar Sandipan

    1994-01-01

    Full Text Available Two cases of subcutaneos granuloma annulare are reported. Clinical presentation was in the form of hard subcutaneous nodules; histopathology confirmed the clinical diagnosis. The cases were unique because of onset in adult hood, occurrence over unusual sites and absence of classical lesions of granuloma annulare elsewhere.

  12. Subcutaneous granuloma annulare

    Directory of Open Access Journals (Sweden)

    Dhar Sandipan

    1993-01-01

    Full Text Available Two cases of subcutaneous granuloma annulare are reported. Clinical presentation was in the form of hard subcutaneous nodules, histopathology confirmed the clinical diagnosis. The cases were unique because of onset in adult age, occurrence over unusual sites and absence of classical lesions of granuloma annulare elsewhere.

  13. Channelling contrast analysis of lattice images: Conditions for probe-insensitive STEM

    Energy Technology Data Exchange (ETDEWEB)

    Rossouw, Chris J., E-mail: chris.rossouw@monash.edu [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Dwyer, Christian [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Katz-Boon, Hadas; Etheridge, Joanne [Monash Centre for Electron Microscopy, Monash University, Victoria 3800 (Australia); Department of Materials Engineering, Monash University, Victoria 3800 (Australia)

    2014-01-15

    Quantitative analysis of lattice resolved images generated by scanning transmission electron microscopy (STEM) requires specification of probe characteristics, such as defocus, aberration and source distribution. In this paper we show that knowledge of such characteristics is unnecessary for quantitative interpretation, if the signal is integrated over a unit cell. Such a condition, whether the result of experimental setup or post-processing of lattice resolved images, reduces the intensity distribution to that of channelling contrast, where the signal for plane wave incidence is averaged over the angular range of the probe, and the result is independent of the probe characteristics. We use a Bloch wave model to show analytically how this applies to all forms of STEM imaging, such as that formed by annular dark field or backscatter detection, as well as characteristic X-ray fluorescence or electron energy loss. As a specific example, we consider how the signal from an annular dark field detector can be used to determine specimen thickness via a transfer curve for the zone axis and scattering geometries employed. This method has advantages over matching lattice images with calculations since these are sensitive to probe coherence and aberration, and saturation of the on-column intensity is approached more rapidly. - Highlights: • Analysis of lattice-resolved STEM images to form channelling contrast. • Conditions for analysis to be independent of probe aberrations are established. • Analysis applicable to STEM imaging using ADF, BSE, X-ray and EELS detection. • Specifically applied to ADF imaging for thickness of Au nanoparticles.

  14. Complex dark-field contrast in grating-based x-ray phase contrast imaging

    Science.gov (United States)

    Yang, Yi; Tang, Xiangyang

    2015-03-01

    Without assuming that the sub-pixel microstructures of an object to be imaged distribute in space randomly, we investigate the influence of the object's microstructures on grating-based x-ray phase contrast imaging. Our theoretical analysis and 3D computer simulation study based on the paraxial Fresnel-Kirchhoff theory show that the existing dark-field contrast can be generalized into a complex dark-field contrast in a way such that its imaginary part quantifies the effect of the object's sub-pixel microstructures on the phase of intensity oscillations. A method based on the phase-attenuation duality that holds for soft tissues to be imaged at high x-ray energies is proposed to retrieve the imaginary part of the complex dark-field contrast for imaging. In comparison to the existing dark-field contrast, the imaginary part of complex dark-field contrast exhibits significantly stronger selectivity on the shape of the object's sub-pixel microstructures. Thus the x-ray imaging corresponding to the imaginary part of complex dark-field contrast can provide additional and complementary information to that corresponding to the attenuation contrast, phase contrast and the existing dark-field contrast.

  15. Quantification of the sensitivity range in neutron dark-field imaging

    Energy Technology Data Exchange (ETDEWEB)

    Betz, B.; Harti, R. P.; Hovind, J.; Kaestner, A.; Lehmann, E.; Grünzweig, C. [Paul Scherrer Institute, LNS, Neutron Imaging and Activation Group, CH-5232 Villigen (Switzerland); Strobl, M. [European Spallation Source ESS, 22100 Lund, Sweden and University of Copenhagen, 2100 Copenhagen (Denmark); Van Swygenhoven, H. [Ecole Polytechnique Fédérale de Lausanne, NXMM Laboratory, IMX, CH-1015 Lausanne, Switzerland and Paul Scherrer Institut, NXMM, CH-5232 Villigen (Switzerland)

    2015-12-15

    In neutron grating interferometry, the dark-field image visualizes the scattering properties of samples in the small-angle and ultra-small-angle scattering range. These angles correspond to correlation lengths from several hundred nanometers up to several tens of micrometers. In this article, we present an experimental study that demonstrates the potential of quantitative neutron dark-field imaging. The dark-field signal for scattering from different particle sizes and concentrations of mono-dispersive polystyrene particles in aqueous solution is compared to theoretical predictions and the good agreement between measurements and calculations underlines the quantitative nature of the measured values and reliability of the technique with neutrons.

  16. Annular pancreas (image)

    Science.gov (United States)

    Annular pancreas is an abnormal ring or collar of pancreatic tissue that encircles the duodenum (the part of the ... intestine that connects to stomach). This portion of pancreas can constrict the duodenum and block or impair ...

  17. Reconstruction of scalar and vectorial components in X-ray dark-field tomography.

    Science.gov (United States)

    Bayer, Florian L; Hu, Shiyang; Maier, Andreas; Weber, Thomas; Anton, Gisela; Michel, Thilo; Riess, Christian P

    2014-09-01

    Grating-based X-ray dark-field imaging is a novel technique for obtaining image contrast for object structures at size scales below setup resolution. Such an approach appears particularly beneficial for medical imaging and nondestructive testing. It has already been shown that the dark-field signal depends on the direction of observation. However, up to now, algorithms for fully recovering the orientation dependence in a tomographic volume are still unexplored. In this publication, we propose a reconstruction method for grating-based X-ray dark-field tomography, which models the orientation-dependent signal as an additional observable from a standard tomographic scan. In detail, we extend the tomographic volume to a tensorial set of voxel data, containing the local orientation and contributions to dark-field scattering. In our experiments, we present the first results of several test specimens exhibiting a heterogeneous composition in microstructure, which demonstrates the diagnostic potential of the method. PMID:25136091

  18. Immunolocalization of multiple membrane proteins on a carbon replica with STEM and EDX

    International Nuclear Information System (INIS)

    We present a method for immunolabeling of multiple species of membrane proteins with high spatial resolution. It allows differentiation of equally sized very small markers with different chemical compositions, which leads to high labeling efficiency and reduces steric hindrance of closely spaced immunolabeled biomolecules. Markers such as CdSe/ZnS semiconductor quantum dots and colloidal gold particles are distinguished by differential contrast in high-angle annular detector dark-field STEM mode or by EDX microanalysis of their elemental contents. This method was tested by observation of labeled AMPA- and NMDA-type glutamate receptors on sodium-dodecyl-sulfate-digested replica prepared from rat hippocampus. To improve particle visibility and detectability, the replica films were made exclusively with carbon to avoid the high background of conventional platinum/carbon replica. Extension of the method is suggested by detection of 1.4 nm nanogold particles and its potential application in the biological imaging research.

  19. Generalized granuloma annulare

    Directory of Open Access Journals (Sweden)

    Khatri M

    1995-01-01

    Full Text Available A 35-years-old female patient had generalized pruritic papular lesions, distributed like dermatitis herpetiformis for last 4 years. Histopathologic changes were typical of granuloma annulare with negative results of direct immunofluorescence. The patient did not have association of diabetes mellitus or any other systemic disease. She failed to respond to dapsone therapy and 13-cis-retinoic acid.

  20. Annular Planar Monopole Antennas

    OpenAIRE

    Chen, Z. N.; Ammann, Max; Chia, W.Y. W.; See, T.S. P.

    2002-01-01

    A type of annular planar monopole antenna is presented. The impedance and radiation characteristics of the monopole with different holes and feed gaps are experimentally examined. The measured results demonstrate that the proposed antenna is capable of providing significantly broad impedance bandwidth with acceptable radiation performance.

  1. Dark-field electron holography for the measurement of geometric phase

    Energy Technology Data Exchange (ETDEWEB)

    Hytch, M.J., E-mail: hytch@cemes.fr [CEMES-CNRS and Universite de Toulouse, 29 rue Jeanne Marvig, F-31055 Toulouse (France); Houdellier, F.; Huee, F.; Snoeck, E. [CEMES-CNRS and Universite de Toulouse, 29 rue Jeanne Marvig, F-31055 Toulouse (France)

    2011-07-15

    The genesis, theoretical basis and practical application of the new electron holographic dark-field technique for mapping strain in nanostructures are presented. The development places geometric phase within a unified theoretical framework for phase measurements by electron holography. The total phase of the transmitted and diffracted beams is described as a sum of four contributions: crystalline, electrostatic, magnetic and geometric. Each contribution is outlined briefly and leads to the proposal to measure geometric phase by dark-field electron holography (DFEH). The experimental conditions, phase reconstruction and analysis are detailed for off-axis electron holography using examples from the field of semiconductors. A method for correcting for thickness variations will be proposed and demonstrated using the phase from the corresponding bright-field electron hologram. -- Highlights: {yields} Unified description of phase measurements in electron holography. {yields} Detailed description of dark-field electron holography for geometric phase measurements. {yields} Correction procedure for systematic errors due to thickness variations.

  2. Dark-field electron holography for the measurement of geometric phase

    International Nuclear Information System (INIS)

    The genesis, theoretical basis and practical application of the new electron holographic dark-field technique for mapping strain in nanostructures are presented. The development places geometric phase within a unified theoretical framework for phase measurements by electron holography. The total phase of the transmitted and diffracted beams is described as a sum of four contributions: crystalline, electrostatic, magnetic and geometric. Each contribution is outlined briefly and leads to the proposal to measure geometric phase by dark-field electron holography (DFEH). The experimental conditions, phase reconstruction and analysis are detailed for off-axis electron holography using examples from the field of semiconductors. A method for correcting for thickness variations will be proposed and demonstrated using the phase from the corresponding bright-field electron hologram. -- Highlights: → Unified description of phase measurements in electron holography. → Detailed description of dark-field electron holography for geometric phase measurements. → Correction procedure for systematic errors due to thickness variations.

  3. Quantification of the sensitivity range in neutron dark-field imaging.

    Science.gov (United States)

    Betz, B; Harti, R P; Strobl, M; Hovind, J; Kaestner, A; Lehmann, E; Van Swygenhoven, H; Grünzweig, C

    2015-12-01

    In neutron grating interferometry, the dark-field image visualizes the scattering properties of samples in the small-angle and ultra-small-angle scattering range. These angles correspond to correlation lengths from several hundred nanometers up to several tens of micrometers. In this article, we present an experimental study that demonstrates the potential of quantitative neutron dark-field imaging. The dark-field signal for scattering from different particle sizes and concentrations of mono-dispersive polystyrene particles in aqueous solution is compared to theoretical predictions and the good agreement between measurements and calculations underlines the quantitative nature of the measured values and reliability of the technique with neutrons. PMID:26724039

  4. Small-animal dark-field radiography for pulmonary emphysema evaluation

    Science.gov (United States)

    Yaroshenko, Andre; Meinel, Felix G.; Hellbach, Katharina; Bech, Martin; Velroyen, Astrid; Müller, Mark; Bamberg, Fabian; Nikolaou, Konstantin; Reiser, Maximilian F.; Yildirim, Ali Ã.-.; Eickelberg, Oliver; Pfeiffer, Franz

    2014-03-01

    Chronic obstructive pulmonary disease (COPD) is one of the leading causes of morbidity and mortality worldwide and emphysema is one of its main components. The disorder is characterized by irreversible destruction of the alveolar walls and enlargement of distal airspaces. Despite the severe changes in the lung tissue morphology, conventional chest radiographs have only a limited sensitivity for the detection of mild to moderate emphysema. X-ray dark-field is an imaging modality that can significantly increase the visibility of lung tissue on radiographic images. The dark-field signal is generated by coherent, small-angle scattering of x-rays on the air-tissue interfaces in the lung. Therefore, morphological changes in the lung can be clearly visualized on dark-field images. This is demonstrated by a preclinical study with a small-animal emphysema model. To generate a murine model of pulmonary emphysema, a female C57BL/6N mouse was treated with a single orotracheal application of porcine pancreatic elastase (80 U/kg body weight) dissolved in phosphate-buffered saline (PBS). Control mouse received PBS. The mice were imaged using a small-animal dark-field scanner. While conventional x-ray transmission radiography images revealed only subtle indirect signs of the pulmonary disorder, the difference between healthy and emphysematous lungs could be clearly directly visualized on the dark-field images. The dose applied to the animals is compatible with longitudinal studies. The imaging results correlate well with histology. The results of this study reveal the high potential of dark-field radiography for clinical lung imaging.

  5. Multiscale 3D characterization with dark-field x-ray microscopy

    DEFF Research Database (Denmark)

    Simons, Hugh; Jakobsen, Anders Clemen; Ahl, Sonja Rosenlund;

    2016-01-01

    Dark-field x-ray microscopy is a new way to three-dimensionally map lattice strain and orientation in crystalline matter. It is analogous to dark-field electron microscopy in that an objective lens magnifies diffracting features of the sample; however, the use of high-energy synchrotron x...... of the technique are presented-mapping the evolution of subgrains during the processing of plastically deformed aluminum, mapping domains and strain fields in ferroelectric crystals, and the three-dimensional mapping of strain fields around individual dislocations. This ability to directly characterize complex...

  6. Detection of sub-pixel fractures in X-ray dark-field tomography

    Energy Technology Data Exchange (ETDEWEB)

    Lauridsen, Torsten; Feidenhans' l, Robert [University of Copenhagen, Niels Bohr Institute, Copenhagen (Denmark); Willner, Marian; Pfeiffer, Franz [Technische Universitaet Muenchen, Department of Physics and Institute of Medical Engineering, Garching (Germany); Bech, Martin [Lund University, Medical Radiation Physics, Lund (Sweden)

    2015-11-15

    We present a new method for detecting fractures in solid materials below the resolution given by the detector pixel size by using grating-based X-ray interferometry. The technique is particularly useful for detecting sub-pixel cracks in large samples where the size of the sample is preventing high-resolution μCT studies of the entire sample. The X-ray grating interferometer produces three distinct modality signals: absorption, phase and dark field. The method utilizes the unique scattering features of the dark-field signal. We have used tomograms reconstructed from each of the three signals to detect cracks in a model sample consisting of stearin. (orig.)

  7. Dark-field hyperlens: Super-resolution imaging of weakly scattering objects

    DEFF Research Database (Denmark)

    Repän, Taavi; Lavrinenko, Andrei; Zhukovsky, Sergei

    2015-01-01

    numerically demonstrate that as the result of such filtering, the image plane only contains scattered light from subwavelength features of the objects and is completely free from background illumination. Similar in spirit to conventional dark-field microscopy, the proposed dark-field hyperlens is shown to...... enhance the subwavelength image contrast by more than two orders of magnitude. These findings are essential for optical imaging of weakly scattering subwavelength objects, such as real-time dynamic nanoscopy of label-free biological objects....

  8. Influence of nuclear quantum effects on frozen phonon simulations of electron vortex beam HAADF-STEM images.

    Science.gov (United States)

    Löfgren, André; Zeiger, Paul; Kocevski, Vancho; Rusz, Ján

    2016-05-01

    We have evaluated atomic resolution high-angle annular dark field images with ordinary beams and electron vortex beams for thin crystals of bcc iron, explicitly considering the atomic vibrations using molecular dynamics. The shape of the image representing an atomic column depends on the orbital angular momentum, sample thickness and temperature. For electron vortex beams we observe characteristic doughnut-shaped images of atomic columns. It is shown how the thermal diffuse scattering reduces the depth of their central minima, which get further smeared by finite source size effects. In addition, it is shown that in calculations of HAADF-STEM images at low temperatures one has to explicitly consider the nuclear quantum effects (zero point vibrations), otherwise the effect of atomic vibrations is strongly underestimated. PMID:26852870

  9. Improvement of Sidestream Dark Field Imaging with an Image Acquisition Stabilizer

    NARCIS (Netherlands)

    G.M. Balestra (Gianmarco); R. Bezemer (Rick); E.C. Boerma (Christiaan); Z-Y. Yong (Ze-Yie); K.D. Sjauw (Krishan); A.E. Engstrom (Annemarie); M. Koopmans (Matty); C. Ince (Can)

    2010-01-01

    textabstractBackground: In the present study we developed, evaluated in volunteers, and clinically validated an image acquisition stabilizer (IAS) for Sidestream Dark Field (SDF) imaging.Methods: The IAS is a stainless steel sterilizable ring which fits around the SDF probe tip. The IAS creates adhe

  10. The persistence length of double stranded DNA determined using dark field tethered particle motion

    NARCIS (Netherlands)

    Brinkers, S.; Dietrich, H.R.C.; De Groote, F.H.; Young, I.T.; Rieger, B.

    2009-01-01

    The wormlike chain model describes the micromechanics of semiflexible polymers by introducing the persistence length. We propose a method of measuring the persistence length of DNA in a controllable near-native environment. Using a dark field microscope, the projected positions of a gold nanoparticl

  11. Coherent superposition in grating-based directional dark-field imaging.

    Directory of Open Access Journals (Sweden)

    Andreas Malecki

    Full Text Available X-ray dark-field scatter imaging allows to gain information on the average local direction and anisotropy of micro-structural features in a sample well below the actual detector resolution. For thin samples the morphological interpretation of the signal is straight forward, provided that only one average orientation of sub-pixel features is present in the specimen. For thick samples, however, where the x-ray beam may pass structures of many different orientations and dimensions, this simple assumption in general does not hold and a quantitative description of the resulting directional dark-field signal is required to draw deductions on the morphology. Here we present a description of the signal formation for thick samples with many overlying structures and show its validity in experiment. In contrast to existing experimental work this description follows from theoretical predictions of a numerical study using a Fourier optics approach. One can easily extend this description and perform a quantitative structural analysis of clinical or materials science samples with directional dark-field imaging or even direction-dependent dark-field CT.

  12. 基于涡旋光照明的暗场数字全息显微方法研究%Dark-field digital holographic microscopy by using vortex b eam illumination

    Institute of Scientific and Technical Information of China (English)

    赵应春; 张秀英; 袁操今; 聂守平; 朱竹青; 王林; 李杨; 贡丽萍; 冯少彤

    2014-01-01

    提出了一种基于涡旋光照明的暗场数字全息显微方法。从理论上阐述了涡旋光环形照明原理和暗场数字全息显微原理,分析了涡旋光的准无衍射特性对成像的影响;搭建了相应的数字全息显微成像系统,采用690 nm的聚苯乙烯小球作为实验样品;最后通过对小球明暗场下数字全息显微再现像的分析对比,证明该方法可以有效地提高数字全息系统的分辨率,同时增强了再现像的对比度。%We propose a dark-field digital holographic microscopy (DHM) by using vortex beam illumination. In this paper, the annular illumination of vortex beam and the dark-field DHM imaging system are theoretically analyzed, and the quasi-nondiffracting property of the vortex beam is discussed. A corresponding DHM imaging system is established. The polystyrene spheres each with a size of 690 nm are utilized as objects in the experiment. By comparing the results of reconstructed images under bright-field illumination with those under dark-field illumination DHM, it is proved that the resolution of dark-field DHM under speckle-field illumination is improved and the contrast of its reconstructed image is enhanced accordingly.

  13. Double aberration-corrected TEM/STEM of tungstated zirconia nanocatalysts for the synthesis of paracetamol

    Energy Technology Data Exchange (ETDEWEB)

    Yoshida, K; Boyes, E D; Gai, P L [York JEOL Nanocentre (United Kingdom); Shiju, N R; Brown, D R, E-mail: pgb500@york.ac.u [Department of Chemical and Biological Sciences, University of Huddersfield, Huddersfield, HD1 3DH (United Kingdom)

    2010-07-01

    We report highly active tungstated zirconia nanocatalysts for the synthesis of paracetamol by Beckmann rearrangement of 4-hydroxyacetophenone oxime. Double aberration-corrected (2AC)-TEM/STEM studies were performed in a JEOL 2200FS FEG TEM/STEM at the 1 Angstrom (1 A = 0.1 nanometer) level. Observations at close to zero defocus were carried out using the AC-TEM as well as AC-STEM including high angle annular dark field (HAADF) imaging, from the same areas of the catalyst crystallites. The studies from the same areas have revealed the location and the nanostructure of the polytungstate species (clusters) and the nanograins of zirconia. The AC (S)TEM was crucial to observe the nanostructure and location of polytungstate clusters on the zirconia grains. Polytungstate clusters as small as 0.5 nm have been identified using the HAADF-STEM. The nanostructures of the catalyst and the W surface density have been correlated with paracetamol reaction studies. The results demonstrate the nature of active sites and high activity of the tungstated zirconia nanocatalyst, which is an environmentally clean alternative to the current homogeneous process.

  14. [Disseminated granuloma annulare].

    Science.gov (United States)

    Kansky, A

    1975-09-01

    A case of generalized granuloma annulare in a 55 year old man is reported. The disease appeared five years before the first admission to the hospital. A large number of bluish-red or skin-colour papules were scattered mainly around the earlobes, buttocks and on the extremities. Some of the lesions were lined up in rings or plaques. Small depigmented and brownish scars were present. Two biopsies revealed characteristic foci of complete collagen degeneration accompanied by a palisading infiltrate in the upper dermis. Treatment with tuberculostatics and antimalarics was without improvement. The lesions cleared after a course of prednison, but reappeared when the drug was discontinued.

  15. Annular recuperator design

    Science.gov (United States)

    Kang, Yungmo

    2005-10-04

    An annular heat recuperator is formed with alternating hot and cold cells to separate counter-flowing hot and cold fluid streams. Each cold cell has a fluid inlet formed in the inner diameter of the recuperator near one axial end, and a fluid outlet formed in the outer diameter of the recuperator near the other axial end to evenly distribute fluid mass flow throughout the cell. Cold cells may be joined with the outlet of one cell fluidly connected to the inlet of an adjacent downstream cell to form multi-stage cells.

  16. Measuring composition in InGaN from HAADF-STEM images and studying the temperature dependence of Z-contrast

    International Nuclear Information System (INIS)

    In this contribution, the indium concentration profile of an InxGa1−xN/GaN five-fold multi quantum well structure is measured from high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) images. The results are compared with an atom probe tomography study. Indium concentrations in the range of 26 at.% to 33 at.% are measured in the centre of the quantum wells. An additional indium layer of 14 at.% has been found on top of the quantum wells. In the second part, the temperature dependence of measured intensities in GaN is investigated. Here, multislice calculations in the frozen lattice approximation are carried out in dependence of specimen thickness and compared to experimental data. An increase of intensity with specimen temperature is found

  17. Pulmonary emphysema diagnosis using a preclinical small-animal X-ray dark-field scanner

    International Nuclear Information System (INIS)

    Pulmonary emphysema is one of the leading causes of morbidity and mortality worldwide that is difficult to detect using conventional x-ray radiographic methods. For emphysematous lungs with enlarged distal airspaces, x-ray scattering decreases and transmission increases, as has been demonstrated by the proof-of-principle experiments with brilliant x-rays from a synchrotron source. Therefore, combination of the transmission and dark-field signals leads to a novel diagnostic approach for pulmonary emphysema. In this study, images of excised murine lungs with pulmonary emphysema and control lungs were acquired using a compact phase- and dark-field scanner with a polychromatic source and a cone-beam geometry. The data analysis revealed a clear distinction between the two groups in the per-pixel scatter plot. The main difference was observed in the angle of the distribution to the vertical. The presented study reveals the high potential of the approach for the pulmonary emphysema diagnosis.

  18. Sub-pixel porosity revealed by x-ray scatter dark field imaging

    Science.gov (United States)

    Revol, V.; Jerjen, I.; Kottler, C.; Schütz, P.; Kaufmann, R.; Lüthi, T.; Sennhauser, U.; Straumann, U.; Urban, C.

    2011-08-01

    X-ray scatter dark field imaging based on the Talbot-Lau interferometer allows for the measurement of ultra-small angle x-ray scattering. The latter is related to the variations in the electron density in the sample at the sub- and micron-scale. Therefore, information on features of the object below the detector resolution can be revealed. In this article, it is demonstrated that scatter dark field imaging is particularly adapted to the study of a material's porosity. An interferometer, optimized for x-ray energies around 50 keV, enables the investigation of aluminum welding with conventional laboratory x-ray tubes. The results show an unprecedented contrast between the pool and the aluminum workpiece. Our conclusions are confirmed due to micro-tomographic three-dimensional reconstructions of the same object with a microscopic resolution.

  19. Pulmonary emphysema diagnosis using a preclinical small-animal X-ray dark-field scanner

    Energy Technology Data Exchange (ETDEWEB)

    Yaroshenko, Andre; Bech, Martin; Tapfer, Arne; Velroyen, Astrid; Pfeiffer, Franz [Department of Physics, Technische Universitaet Muenchen (Germany); Meinel, Felix; Nikolaou, Konstantin; Reiser, Maximilian [Institute of Clinical Radiology, Ludwig-Maximilians-University Hospital Munich, Muenchen (Germany); Bohla, Alexander; Yildirim, Ali Oender; Eickelberg, Oliver [Institute of Lung Biology and Disease, Helmholtz Zentrum Muenchen (Germany)

    2013-07-01

    Pulmonary emphysema is one of the leading causes of morbidity and mortality worldwide that is difficult to detect using conventional x-ray radiographic methods. For emphysematous lungs with enlarged distal airspaces, x-ray scattering decreases and transmission increases, as has been demonstrated by the proof-of-principle experiments with brilliant x-rays from a synchrotron source. Therefore, combination of the transmission and dark-field signals leads to a novel diagnostic approach for pulmonary emphysema. In this study, images of excised murine lungs with pulmonary emphysema and control lungs were acquired using a compact phase- and dark-field scanner with a polychromatic source and a cone-beam geometry. The data analysis revealed a clear distinction between the two groups in the per-pixel scatter plot. The main difference was observed in the angle of the distribution to the vertical. The presented study reveals the high potential of the approach for the pulmonary emphysema diagnosis.

  20. Rare Events in Remote Dark-Field Spectroscopy: An Ecological Case Study of Insects

    OpenAIRE

    Runemark, Anna; Wellenreuther, Maren; Jayaweera, Hiran; Svanberg, Sune; Brydegaard Sørensen, Mikkel

    2012-01-01

    In this paper, a novel detection scheme for the monitoring of insect ecosystems is presented. Our method is based on the remote acquisition of passive sunlight scattering by two insect species. Procedures to identify rare events in remote dark-field spectroscopy are explained. We further demonstrate how to reduce the spectral representation, and how to discriminate between sexes, using a hierarchical clustering analysis. One-day cycle showing the temporal activities of the two sexes as well a...

  1. Weak-beam dark-field electron tomography of dislocations in GaN

    International Nuclear Information System (INIS)

    By combining weak-beam dark-field imaging with tomography, we have been able to reconstruct the three-dimensional structure of dislocation arrays in GaN. With a mixture of both threading and in-plane dislocations, owing to plastic relaxation of the film, we look at how well each dislocation is reconstructed and what limits are imposed by way of dislocation density and material anisotropy

  2. Quantitative Neutron Dark-field Imaging through Spin-Echo Interferometry

    OpenAIRE

    Markus Strobl; Morten Sales; Jeroen Plomp; Bouwman, Wim G.; Tremsin, Anton S.; Anders Kaestner; Catherine Pappas; Klaus Habicht

    2015-01-01

    Neutron dark-field imaging constitutes a seminal progress in the field of neutron imaging as it combines real space resolution capability with information provided by one of the most significant neutron scattering techniques, namely small angle scattering. The success of structural characterizations bridging the gap between macroscopic and microscopic features has been enabled by the introduction of grating interferometers so far. The induced interference pattern, a spatial beam modulation, a...

  3. Non-invasive Differentiation of Kidney Stone Types using X-ray Dark-Field Radiography

    OpenAIRE

    Kai Scherer; Eva Braig; Konstantin Willer; Marian Willner; Fingerle, Alexander A.; Michael Chabior; Julia Herzen; Matthias Eiber; Bernhard Haller; Michael Straub; Heike Schneider; Ernst J. Rummeny; Peter B Noël; Franz Pfeiffer

    2015-01-01

    Treatment of renal calculi is highly dependent on the chemical composition of the stone in question, which is difficult to determine using standard imaging techniques. The objective of this study is to evaluate the potential of scatter-sensitive X-ray dark-field radiography to differentiate between the most common types of kidney stones in clinical practice. Here, we examine the absorption-to-scattering ratio of 118 extracted kidney stones with a laboratory Talbot-Lau Interferometer. Dependin...

  4. Partial dark-field microscopy for investigating domain structures of double-layer microsphere film

    OpenAIRE

    Joon Heon Kim; Jung Su Park

    2015-01-01

    A lateral dislocation in a double-layer microsphere film is very difficult to identify because the constituent domains have the same two-dimensional crystalline orientation. Orientation-sensitive optical techniques cannot resolve this issue. Here, we demonstrate that partial dark-field (pDF) optical microscopy can be very effective in identifying this type of domain boundary and dislocation of a close-packed microsphere double-layer. Using the hexagonal symmetry of the close-packed microspher...

  5. Application of HAADF STEM image analysis to structure determination in rotationally disordered and amorphous multilayered films

    Science.gov (United States)

    Mitchson, Gavin; Ditto, Jeffrey; Woods, Keenan N.; Westover, Richard; Page, Catherine J.; Johnson, David C.

    2016-08-01

    We report results from high angle annular dark field scanning transmission electron microscopy (HAADF STEM) image analysis of complex semi-crystalline and amorphous materials, and apply the insights gained from local structure information towards global structure determination. Variations in HAADF STEM intensities for a rotationally disordered heterostructure and an amorphous oxide film are statistically analyzed to extract information regarding the inhomogeneity of the films perpendicular to the substrate. By assuming chemical homogeneity in the film axis parallel to the substrate, the signal intensity variation parallel to the substrate is used to estimate the signal noise level, allowing evaluation of the significance of intensity differences in the substrate normal direction. The positions of HAADF STEM intensity peaks in the perpendicular direction, averaged from multiple images, provide a valuable initial model for a Rietveld refinement of the global c-axis structure of the heterostructure. For an amorphous multi-coat solution-cast oxide sample, the analysis reveals statistically significant variations in the HAADF STEM intensity profile perpendicular to the substrate. These variations indicate an inhomogeneous density profile, presumably related to the spin-casting of individual layers and have implications for understanding the chemical interactions that occur between layers when preparing multilayer amorphous oxide films from solution.

  6. Axisymmetric annular curtain stability

    International Nuclear Information System (INIS)

    A temporal stability analysis was carried out to investigate the stability of an axially moving viscous annular liquid jet subject to axisymmetric disturbances in surrounding co-flowing viscous gas media. We investigated in this study the effects of inertia, surface tension, the gas-to-liquid density ratio, the inner-to-outer radius ratio and the gas-to-liquid viscosity ratio on the stability of the jet. With an increase in inertia, the growth rate of the unstable disturbances is found to increase. The dominant (or most unstable) wavenumber decreases with increasing Reynolds number for larger values of the gas-to-liquid viscosity ratio. However, an opposite tendency for the most unstable wavenumber is predicted for small viscosity ratio in the same inertia range. The surrounding gas density, in the presence of viscosity, always reduces the growth rate, hence stabilizing the flow. There exists a critical value of the density ratio above which the flow becomes stable for very small viscosity ratio, whereas for large viscosity ratio, no stable flow appears in the same range of the density ratio. The curvature has a significant destabilizing effect on the thin annular jet, whereas for a relatively thick jet, the maximum growth rate decreases as the inner radius increases, irrespective of the surrounding gas viscosity. The degree of instability increases with Weber number for a relatively large viscosity ratio. In contrast, for small viscosity ratio, the growth rate exhibits a dramatic dependence on the surface tension. There is a small Weber number range, which depends on the viscosity ratio, where the flow is stable. The viscosity ratio always stabilizes the flow. However, the dominant wavenumber increases with increasing viscosity ratio. The range of unstable wavenumbers is affected only by the curvature effect. (paper)

  7. Rotordynamic Analysis of Textured Annular Seals With Multiphase (Bubbly Flow

    Directory of Open Access Journals (Sweden)

    Gérard PINEAU

    2011-09-01

    Full Text Available For some applications it must be considered that the flow in the annular seal contains a mixture of liquid and gas. The multiphase character of the flow is described by the volume fraction of gas (usually air contained in the liquid under the form of bubbles.The fluid is then a homogenous mixture of air and liquid all thru the annular seal. Its local gas volume fraction depends on the pressure field and is calculated by using a simplified form of the Rayleigh-Plesset equation.The influence of such of a multiphase (bubbly flow on the dynamic characteristics of a straight annular seal is minimal because the volume of the fluid is reduced.The situation is quite different for textured annular (damper seals provided with equally spaced deep cavities intended to increase the damping capabilities and to reduce the leakage flow rate.As a by-product, the volume of the fluid in the seal increases drastically and the compressibility effects stemming from the bubbly nature of the flow are largely increased even for a low gas volume fraction. The present work depicts the influence of the gas volume fraction on the dynamic characteristics of a textured annular seal. It is shown that variations of the gas volume fraction between 1% and 0.1% can lead to frequency dependent stiffness, damping and added mass coefficients.

  8. Emphysema diagnosis using X-ray dark-field imaging at a laser-driven compact synchrotron light source

    OpenAIRE

    Schleede, Simone; Meinel, Felix G.; Bech, Martin; Herzen, Julia; Achterhold, Klaus; Potdevin, Guillaume; Malecki, Andreas; Adam-Neumair, Silvia; Thieme, Sven F.; Bamberg, Fabian; Nikolaou, Konstantin; Bohla, Alexander; Yildirim, Ali Ö.; Loewen, Roderick; Gifford, Martin

    2012-01-01

    In early stages of various pulmonary diseases, such as emphysema and fibrosis, the change in X-ray attenuation is not detectable with absorption-based radiography. To monitor the morphological changes that the alveoli network undergoes in the progression of these diseases, we propose using the dark-field signal, which is related to small-angle scattering in the sample. Combined with the absorption-based image, the dark-field signal enables better discrimination between healthy and emphysemato...

  9. Annular Hybrid Rocket Motor Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Engineers at SpaceDev have conducted a preliminary design and analysis of a proprietary annular design concept for a hybrid motor. A U.S. Patent application has...

  10. Manufacture of annular cermet articles

    Science.gov (United States)

    Forsberg, Charles W.; Sikka, Vinod K.

    2004-11-02

    A method to produce annular-shaped, metal-clad cermet components directly produces the form and avoids multiple fabrication steps such as rolling and welding. The method includes the steps of: providing an annular hollow form with inner and outer side walls; filling the form with a particulate mixture of ceramic and metal; closing, evacuating, and hermetically sealing the form; heating the form to an appropriate temperature; and applying force to consolidate the particulate mixture into solid cermet.

  11. Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

    Science.gov (United States)

    Yazaki, Akio; Kim, Chanju; Chan, Jacky; Mahjoubfar, Ata; Goda, Keisuke; Watanabe, Masahiro; Jalali, Bahram

    2014-06-01

    High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection enables real-time identification of difficult-to-detect features on weakly reflecting surfaces and hence renders the method much more practical than in the previously demonstrated bright-field configuration. Consequently, our inspector provides nearly 1000 times higher scanning speed than conventional inspectors. To show our method's broad utility, we demonstrate real-time inspection of the surface of various objects (a non-reflective black film, transparent flexible film, and reflective hard disk) for detection of 10 μm or smaller defects on a moving target at 20 m/s within a scan width of 25 mm at a scan rate of 90.9 MHz. Our method holds promise for improving the cost and performance of organic light-emitting diode displays for next-generation smart phones, lithium-ion batteries for green electronics, and high-efficiency solar cells.

  12. Ultrafast dark-field surface inspection with hybrid-dispersion laser scanning

    International Nuclear Information System (INIS)

    High-speed surface inspection plays an important role in industrial manufacturing, safety monitoring, and quality control. It is desirable to go beyond the speed limitation of current technologies for reducing manufacturing costs and opening a new window onto a class of applications that require high-throughput sensing. Here, we report a high-speed dark-field surface inspector for detection of micrometer-sized surface defects that can travel at a record high speed as high as a few kilometers per second. This method is based on a modified time-stretch microscope that illuminates temporally and spatially dispersed laser pulses on the surface of a fast-moving object and detects scattered light from defects on the surface with a sensitive photodetector in a dark-field configuration. The inspector's ability to perform ultrafast dark-field surface inspection enables real-time identification of difficult-to-detect features on weakly reflecting surfaces and hence renders the method much more practical than in the previously demonstrated bright-field configuration. Consequently, our inspector provides nearly 1000 times higher scanning speed than conventional inspectors. To show our method's broad utility, we demonstrate real-time inspection of the surface of various objects (a non-reflective black film, transparent flexible film, and reflective hard disk) for detection of 10 μm or smaller defects on a moving target at 20 m/s within a scan width of 25 mm at a scan rate of 90.9 MHz. Our method holds promise for improving the cost and performance of organic light-emitting diode displays for next-generation smart phones, lithium-ion batteries for green electronics, and high-efficiency solar cells.

  13. Dark-field X-ray microscopy for multiscale structural characterization

    DEFF Research Database (Denmark)

    Simons, Hugh; King, A.; Ludwig, W.;

    2015-01-01

    -dimensional mapping of orientations and stresses on lengths scales from 100 nm to 1mm within embedded sampling volumes. The technique, which allows 'zooming' in and out in both direct and angular space, is demonstrated by an annealing study of plastically deformed aluminium. Facilitating the direct study...... of the interactions between crystalline elements is a key step towards the formulation and validation of multiscale models that account for the entire heterogeneity of a material. Furthermore, dark-field X-ray microscopy is well suited to applied topics, where the structural evolution of internal nanoscale elements...

  14. X-ray dark-field imaging for detection of foreign bodies in food

    DEFF Research Database (Denmark)

    Nielsen, M.S.; Lauridsen, T.; Feidenhans'l, R.;

    2013-01-01

    Conventional X-ray transmission radiography has long been used for online detection of foreign bodies in food products relying on the absorption contrast between the foreign body and food product. In this paper, we present a novel approach for detection of organic foreign bodies such as paper...... and insects in two food products using X-ray dark-field imaging with a grating interferometer. The ability to detect the foreign bodies is quantified using a measure of the contrast-to-noise ratio. © 2012 Elsevier Ltd....

  15. Dark-field digital holographic microscopy for 3D-tracking of gold nanoparticles

    CERN Document Server

    Verpillat, Frédéric; Desbiolles, Pierre; Gross, Michel

    2011-01-01

    We present a new technique that combines off-axis Digital Holography and Dark Field Microscopy to track 100nm gold particles diffusing in water. We show that a single hologram is sufficient to localize several particles in a thick sample with a localization accuracy independent of the particle position. From our measurements we reconstruct the trajectories of the particles and derive their 3D diffusion coefficient. Our results pave the way for quantitative studies of the motion of single nanoparticle in complex media.

  16. Structural characterization of Pt-Pd core-shell nanoparticles by Cs-corrected STEM

    Energy Technology Data Exchange (ETDEWEB)

    Esparza, R., E-mail: resparza@fata.unam.mx [Universidad Nacional Autonoma de Mexico, Centro de Fisica Aplicada y Tecnologia Avanzada (Mexico); Garcia-Ruiz, Amado F. [UPIICSA-COFAA, Instituto Politecnico Nacional (Mexico); Velazquez Salazar, J. J. [University of Texas at San Antonio, Department of Physics and Astronomy (United States); Perez, R. [Universidad Nacional Autonoma de Mexico, Centro de Fisica Aplicada y Tecnologia Avanzada (Mexico); Jose-Yacaman, M. [The University of Texas at San Antonio, Department of Physics and Astronomy (United States)

    2013-01-15

    Pt-Pd core-shell nanoparticles were synthesized using a modified polyol method. A thermal method under refluxing, carrying on the reaction up to 285 Degree-Sign C, has been performed to reduce metallic salts using ethylene glycol as reducer and poly(N-vinyl-2-pyrrolidone) as protective reagent of the formed bimetallic nanoparticles. According to other works, this type of structure has been studied and utilized to successfully increase the catalytic properties of monometallic nanoparticles Pt or Pd. Core-shell bimetallic nanoparticles were structurally characterized using aberration-corrected scanning transmission electron microscopy (Cs-STEM) equipped with a high-angle annular dark field detector, energy-dispersive X-ray spectrometry (EDS), and electron energy-loss spectroscopy (EELS). The high-resolution elemental line scan and mappings were carried out using a combination of STEM-EDS and STEM-EELS. The obtained results show the growth of the Pd shell on the Pt core with polyhedral morphology. The average size of the bimetallic nanoparticles was 13.5 nm and the average size of the core was 8.5 nm; consequently, the thickness of the shell was around 2.5 nm. The growth of the Pd shell on the Pt core is layer by layer, suggesting a Frank-van der Merwe growth mechanism.

  17. Quantitative Neutron Dark-field Imaging through Spin-Echo Interferometry.

    Science.gov (United States)

    Strobl, Markus; Sales, Morten; Plomp, Jeroen; Bouwman, Wim G; Tremsin, Anton S; Kaestner, Anders; Pappas, Catherine; Habicht, Klaus

    2015-01-01

    Neutron dark-field imaging constitutes a seminal progress in the field of neutron imaging as it combines real space resolution capability with information provided by one of the most significant neutron scattering techniques, namely small angle scattering. The success of structural characterizations bridging the gap between macroscopic and microscopic features has been enabled by the introduction of grating interferometers so far. The induced interference pattern, a spatial beam modulation, allows for mapping of small-angle scattering signals and hence addressing microstructures beyond direct spatial resolution of the imaging system with high efficiency. However, to date the quantification in the small angle scattering regime is severely limited by the monochromatic approach. To overcome such drawback we here introduce an alternative and more flexible method of interferometric beam modulation utilizing a spin-echo technique. This novel method facilitates straightforward quantitative dark-field neutron imaging, i.e. the required quantitative microstructural characterization combined with real space image resolution. For the first time quantitative microstructural reciprocal space information from small angle neutron scattering becomes available together with macroscopic image information creating the potential to quantify several orders of magnitude in structure sizes simultaneously. PMID:26560644

  18. Grating-based X-ray Dark-field Computed Tomography of Living Mice

    Directory of Open Access Journals (Sweden)

    A. Velroyen

    2015-10-01

    Full Text Available Changes in x-ray attenuating tissue caused by lung disorders like emphysema or fibrosis are subtle and thus only resolved by high-resolution computed tomography (CT. The structural reorganization, however, is of strong influence for lung function. Dark-field CT (DFCT, based on small-angle scattering of x-rays, reveals such structural changes even at resolutions coarser than the pulmonary network and thus provides access to their anatomical distribution. In this proof-of-concept study we present x-ray in vivo DFCTs of lungs of a healthy, an emphysematous and a fibrotic mouse. The tomographies show excellent depiction of the distribution of structural – and thus indirectly functional – changes in lung parenchyma, on single-modality slices in dark field as well as on multimodal fusion images. Therefore, we anticipate numerous applications of DFCT in diagnostic lung imaging. We introduce a scatter-based Hounsfield Unit (sHU scale to facilitate comparability of scans. In this newly defined sHU scale, the pathophysiological changes by emphysema and fibrosis cause a shift towards lower numbers, compared to healthy lung tissue.

  19. On a dark-field signal generated by micrometer-sized calcifications in phase-contrast mammography

    Science.gov (United States)

    Michel, Thilo; Rieger, Jens; Anton, Gisela; Bayer, Florian; Beckmann, Matthias W.; Durst, Jürgen; Fasching, Peter A.; Haas, Wilhelm; Hartmann, Arndt; Pelzer, Georg; Radicke, Marcus; Rauh, Claudia; Ritter, André; Sievers, Peter; Schulz-Wendtland, Rüdiger; Uder, Michael; Wachter, David L.; Weber, Thomas; Wenkel, Evelyn; Zang, Andrea

    2013-04-01

    We show that a distribution of micrometer-sized calcifications in the human breast which are not visible in clinical x-ray mammography at diagnostic dose levels can produce a significant dark-field signal in a grating-based x-ray phase-contrast imaging setup with a tungsten anode x-ray tube operated at 40 kVp. A breast specimen with invasive ductal carcinoma was investigated immediately after surgery by Talbot-Lau x-ray interferometry with a design energy of 25 keV. The sample contained two tumors which were visible in ultrasound and contrast-agent enhanced MRI but invisible in clinical x-ray mammography, in specimen radiography and in the attenuation images obtained with the Talbot-Lau interferometer. One of the tumors produced significant dark-field contrast with an exposure of 0.85 mGy air-kerma. Staining of histological slices revealed sparsely distributed grains of calcium phosphate with sizes varying between 1 and 40 μm in the region of this tumor. By combining the histological investigations with an x-ray wave-field simulation we demonstrate that a corresponding distribution of grains of calcium phosphate in the form of hydroxylapatite has the ability to produce a dark-field signal which would—to a substantial degree—explain the measured dark-field image. Thus we have found the appearance of new information (compared to attenuation and differential phase images) in the dark-field image. The second tumor in the same sample did not contain a significant fraction of these very fine calcification grains and was invisible in the dark-field image. We conclude that some tumors which are invisible in x-ray absorption mammography might be detected in the x-ray dark-field image at tolerable dose levels.

  20. Adiabatic Steam-Water Annular Flow in an Annular Geometry

    DEFF Research Database (Denmark)

    Andersen, P. S.; Würtz, J.

    1981-01-01

    Experimental results for fully developed steam-water annular flow in annular geometries are presented. Rod and tube film flow rates and axial pressure gradients were measured for mass fluxes between 500 and 2000 kg/m2s, steam qualities between 20 and 60 per cent and pressures ranging from 3 to 9...... MPa. It was found that the measured tube film flow rate per unit tube perimeter is always many times greater than the corresponding rod film flow rate. Possible explanations for this asymmetry are discussed....

  1. Annular lipoatrophy of the ankles.

    Science.gov (United States)

    Dimson, Otobia G; Esterly, Nancy B

    2006-02-01

    Lipoatrophic panniculitis likely represents a group of disorders characterized by an inflammatory panniculitis followed by lipoatrophy. It occurs locally in a variety of settings and has been reported in the literature under various terms, including annular atrophic connective tissue panniculitis of the ankles, annular and semicircular lipoatrophy, abdominal lipoatrophy, and connective tissue panniculitis. Herein, a case of annular lipoatrophy of the ankles is described in a 6-year-old girl with autoimmune thyroid disease. Histologically, a mixed lobular panniculitis with lipophages was present. This pattern resembles that seen in lipoatrophic panniculitis. After a single, acute episode of an inflammatory process with subsequent lipoatrophy, her skin lesions have stabilized for 2 years requiring no treatment.

  2. Four-wave dark-field electron holography for imaging strain fields

    Science.gov (United States)

    Denneulin, T.; Hÿtch, M.

    2016-06-01

    Strain characterization by transmission electron microscopy is an active area of research especially for microelectronics applications. Two-wave dark-field electron holography (DFEH) was previously introduced as a reliable strain mapping technique. Here, DFEH with four electron waves was investigated in order to image equi-displacement lines as amplitude modulations of the holographic fringes. Two perpendicular electrostatic biprisms are used to interfere three reference waves diffracted by a substrate and one object wave diffracted by an epitaxially strained region. This technique provides a different way to represent the displacement field. It might be helpful to obtain information about the strain state during in situ experiments. A dummy p-MOSFET device with embedded SiGe source and drain is used for experimental demonstration.

  3. High energy X-ray phase and dark-field imaging using a random absorption mask

    Science.gov (United States)

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-07-01

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science.

  4. X-ray refraction-contrast computed tomography images using dark-field imaging optics

    International Nuclear Information System (INIS)

    If an x-ray beam containing internal information derived from sample soft tissue is incident upon a Laue-case analyzer, the beam will subsequently split into a forwardly diffracted beam and a separate diffracted beam. Using these beams acquired simultaneously, a refraction-contrast computed tomography (CT) imaging system for biomedical use with lower radiation dose can be easily realized, and has a high depicting capability on the soft tissues compared with conventional x-ray CT based on absorption contrast principles. In this paper, we propose an imaging system using dark-field imaging for CT measurement based on a tandem system of Bragg- and Laue-case crystals with two two-dimensional detectors, along with a data-processing method to extract information on refraction from the measured entangled intensities by use of rocking curve fitting with polynomial functions. Reconstructed images of soft tissues are presented and described.

  5. Manipulation of Nanoparticles Using Dark-Field-Illumination Optical Tweezers with Compensating Spherical Aberration

    Institute of Scientific and Technical Information of China (English)

    ZHOU Jin-Hua; TAO Run-Zhe; HU Zhi-Bin; ZHONG Min-Cheng; WANG Zi-Qiang; CAI Jun; LI Yin-Mei

    2009-01-01

    Based on our previous investigation of optical tweezers with dark field illumination[Chin.Phys.Lett.25(2008)329],nanoparticles at large trap depth axe better viewed in wide field and real time for a long time,but with poor forces.Here we present the mismatched tube length to compensate for spherical aberration of an oil-immersion objective in a glass-water interface in an optical tweezers system for manipulating nanoparticles.In this way,the critical power of stable trapping particles is measured at different trap depths.It is found that trap depth is enlarged for trapping nanoparticles and trapping forces are enhanced at large trap depth.According to the measurement,70-nm particles are manipulated in three dimensions and observed clearly at large appropriate depth.This will expand applications of optical tweezers in a nanometre-scale colloidal system.

  6. High contrast hollow-cone dark field transmission electron microscopy for nanocrystalline grain size quantification.

    Science.gov (United States)

    Yao, Bo; Sun, Tik; Warren, Andrew; Heinrich, Helge; Barmak, Katayun; Coffey, Kevin R

    2010-04-01

    In this paper, we describe hollow-cone dark field (HCDF) transmission electron microscopy (TEM) imaging, with a slightly convergent beam, as an improved technique that is suitable to form high contrast micrographs for nanocrystalline grain size quantification. We also examine the various factors that influence the HCDF TEM image quality, including the conditions of microscopy (alignment, focus and objective aperture size), the properties of the materials imaged (e.g., atomic number, strain, defects), and the characteristics of the TEM sample itself (e.g., thickness, ion milling artifacts). Sample preparation was found to be critical and an initial thinning by wet etching of the substrate (for thin film samples) or tripod polishing (for bulk samples), followed by low-angle ion milling was found to be the preferred approach for preparing high-quality electron transparent samples for HCDF imaging. PMID:20018512

  7. Phase flow rate measurements of annular flows

    OpenAIRE

    Al-Yarubi, Qahtan

    2010-01-01

    In the international oil and gas industry multiphase annular flow in pipelines and wells is extremely important, but not well understood. This thesis reports the development of an efficient and cheap method for measuring the phase flow rates in two phase annular and annular mist flow, in which the liquid phase is electrically conducting, using ultrasonic and conductance techniques. The method measures changes in the conductance of the liquid film formed during annular flow and uses these to c...

  8. Eosinophilic annular erythema in childhood - Case report.

    Science.gov (United States)

    Abarzúa, Alvaro; Giesen, Laura; Silva, Sergio; González, Sergio

    2016-01-01

    Eosinophilic annular erythema is a rare, benign, recurrent disease, clinically characterized by persistent, annular, erythematous lesions, revealing histopathologically perivascular infiltrates with abundant eosinophils. This report describes an unusual case of eosinophilic annular erythema in a 3-year-old female, requiring sustained doses of hydroxychloroquine to be adequately controlled. PMID:27579748

  9. Eosinophilic annular erythema in childhood - Case report*

    Science.gov (United States)

    Abarzúa, Alvaro; Giesen, Laura; Silva, Sergio; González, Sergio

    2016-01-01

    Eosinophilic annular erythema is a rare, benign, recurrent disease, clinically characterized by persistent, annular, erythematous lesions, revealing histopathologically perivascular infiltrates with abundant eosinophils. This report describes an unusual case of eosinophilic annular erythema in a 3-year-old female, requiring sustained doses of hydroxychloroquine to be adequately controlled. PMID:27579748

  10. Benign concentric annular macular dystrophy

    Directory of Open Access Journals (Sweden)

    Luísa Salles de Moura Mendonça

    2015-06-01

    Full Text Available The purpose of the authors is to show clinical findings of a patient with benign concentric annular macular dystrophy, which is an unusual condition, and part of the "bull’s eye" maculopathy differential diagnosis. An ophthalmologic examination with color perception, fluorescein angiography, and ocular electrophysiology was performed.

  11. Defocus and twofold astigmatism correction in HAADF-STEM

    International Nuclear Information System (INIS)

    A new simultaneous autofocus and twofold astigmatism correction method is proposed for High Angle Annular Dark Field Scanning Transmission Electron Microscopy (HAADF-STEM). The method makes use of a modification of image variance, which has already been used before as an image quality measure for different types of microscopy, but its use is often justified on heuristic grounds. In this paper we show numerically that the variance reaches its maximum at Scherzer defocus and zero astigmatism. In order to find this maximum a simultaneous optimization of three parameters (focus, x- and y-stigmators) is necessary. This is implemented and tested on a FEI Tecnai F20. It successfully finds the optimal defocus and astigmatism with time and accuracy, compared to a human operator. -- Research highlights: → A new simultaneous defocus and astigmatism correction method is proposed. → The method does not depend on the image Fourier transform. → The method does not require amorphous area of the sample. → The method is tested numerically as well, as for the real-world application.

  12. Subcutaneous granuloma annulare: radiologic appearance

    International Nuclear Information System (INIS)

    Objective. Granuloma annulare is an uncommon benign inflammatory dermatosis characterized by the formation of dermal papules with a tendency to form rings. There are several clinically distinct forms. The subcutaneous form is the most frequently encountered by radiologists, with the lesion presenting as a superficial mass. There are only a few scattered reports of the imaging appearance of this entity in the literature. We report the radiologic appearance of five cases of subcutaneous granuloma annulare. Design and patients. The radiologic images of five patients (three male, two female) with subcutaneous granuloma annulare were retrospectively studied. Mean patient age was 6.4 years (range, 2-13 years). The lesions occurred in the lower leg (two), foot, forearm, and hand. MR images were available for all lesions, gadolinium-enhanced imaging in three cases, radiographs in four, and bone scintigraphy in one. Results. Radiographs showed unmineralized nodular masses localized to the subcutaneous adipose tissue. The size range, in greatest dimension on imaging studies, was 1-4 cm. MR images show a mass with relatively decreased signal intensity on all pulse sequences, with variable but generally relatively well defined margins. There was extensive diffuse enhancement following gadolinium administration. Conclusion. The radiologic appearance of subcutaneous granuloma annulare is characteristic, typically demonstrating a nodular soft-tissue mass involving the subcutaneous adipose tissue. MR images show a mass with relatively decreased signal intensity on all pulse sequences and variable but generally well defined margins. There is extensive diffuse enhancement following gadolinium administration. Radiographs show a soft-tissue mass or soft-tissue swelling without evidence of bone involvement or mineralization. This radiologic appearance in a young individual is highly suggestive of subcutaneous granuloma annulare. (orig.)

  13. Annular-Efficient Triangulations of 3-manifolds

    CERN Document Server

    Jaco, William

    2011-01-01

    A triangulation of a compact 3-manifold is annular-efficient if it is 0-efficient and the only normal, incompressible annuli are thin edge-linking. If a compact 3-manifold has an annular-efficient triangulation, then it is irreducible, boundary-irreducible, and an-annular. Conversely, it is shown that for a compact, irreducible, boundary-irreducible, and an-annular 3-manifold, any triangulation can be modified to an annular-efficient triangulation. It follows that for a manifold satisfying this hypothesis, there are only a finite number of boundary slopes for incompressible and boundary-incompressible surfaces of a bounded Euler characteristic.

  14. Chemical composition dispersion in bi-metallic nanoparticles: semi-automated analysis using HAADF-STEM

    Energy Technology Data Exchange (ETDEWEB)

    Epicier, T., E-mail: thierry.epicier@insa-lyon.fr [INSA-Lyon, MATEIS CNRS UMR5510, Bat. Blaise Pascal (France); Sato, K. [Institute for Materials Research, Tohoku University, Material Processing and Characterization Division (Japan); Tournus, F. [Universite Lyon 1, LPMCN, UMR 5586 CNRS and Universite de Lyon (France); Konno, T. [Institute for Materials Research, Tohoku University, Material Processing and Characterization Division (Japan)

    2012-09-15

    We present a method using high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) to determine the chemical composition of bi-metallic nanoparticles. This method, which can be applied in a semi-automated way, allows large scale analysis with a statistical number of particles (several hundreds) in a short time. Once a calibration curve has been obtained, e.g., using energy-dispersive X-ray spectroscopy (EDX) measurements on a few particles, the HAADF integrated intensity of each particle can indeed be directly related to its chemical composition. After a theoretical description, this approach is applied to the case of iron-palladium nanoparticles (expected to be nearly stoichiometric) with a mean size of 8.3 nm. It will be shown that an accurate chemical composition histogram is obtained, i.e., the Fe content has been determined to be 49.0 at.% with a dispersion of 10.4 %. HAADF-STEM analysis represents a powerful alternative to fastidious single particle EDX measurements, for the compositional dispersion in alloy nanoparticles.

  15. Visualization of neonatal lung injury associated with mechanical ventilation using x-ray dark-field radiography

    Science.gov (United States)

    Yaroshenko, Andre; Pritzke, Tina; Koschlig, Markus; Kamgari, Nona; Willer, Konstantin; Gromann, Lukas; Auweter, Sigrid; Hellbach, Katharina; Reiser, Maximilian; Eickelberg, Oliver; Pfeiffer, Franz; Hilgendorff, Anne

    2016-04-01

    Mechanical ventilation (MV) and supplementation of oxygen-enriched gas, often needed in postnatal resuscitation procedures, are known to be main risk factors for impaired pulmonary development in the preterm and term neonates. Unfortunately, current imaging modalities lack in sensitivity for the detection of early stage lung injury. The present study reports a new imaging approach for diagnosis and staging of early lung injury induced by MV and hyperoxia in neonatal mice. The imaging method is based on the Talbot-Lau x-ray grating interferometry that makes it possible to quantify the x-ray small-angle scattering on the air-tissue interfaces. This so-called dark-field signal revealed increasing loss of x-ray small-angle scattering when comparing images of neonatal mice undergoing hyperoxia and MV-O2 with animals kept at room air. The changes in the dark field correlated well with histologic findings and provided superior differentiation than conventional x-ray imaging and lung function testing. The results suggest that x-ray dark-field radiography is a sensitive tool for assessing structural changes in the developing lung. In the future, with further technical developments x-ray dark-field imaging could be an important tool for earlier diagnosis and sensitive monitoring of lung injury in neonates requiring postnatal oxygen or ventilator therapy.

  16. Time resolved X-ray Dark-Field Tomography Revealing Water Transport in a Fresh Cement Sample

    Science.gov (United States)

    Prade, Friedrich; Fischer, Kai; Heinz, Detlef; Meyer, Pascal; Mohr, Jürgen; Pfeiffer, Franz

    2016-06-01

    Grating-based X-ray dark-field tomography is a promising technique for biomedical and materials research. Even if the resolution of conventional X-ray tomography does not suffice to resolve relevant structures, the dark-field signal provides valuable information about the sub-pixel microstructural properties of the sample. Here, we report on the potential of X-ray dark-field imaging to be used for time-resolved three-dimensional studies. By repeating consecutive tomography scans on a fresh cement sample, we were able to study the hardening dynamics of the cement paste in three dimensions over time. The hardening of the cement was accompanied by a strong decrease in the dark-field signal pointing to microstructural changes within the cement paste. Furthermore our results hint at the transport of water from certain limestone grains, which were embedded in the sample, to the cement paste during the process of hardening. This is indicated by an increasing scattering signal which was observed for two of the six tested limestone grains. Electron microscopy images revealed a distinct porous structure only for those two grains which supports the following interpretation of our results. When the water filled pores of the limestone grains empty during the experiment the scattering signal of the grains increases.

  17. Dark-field electron holography for the mapping of strain in nanostructures: correcting artefacts and aberrations

    International Nuclear Information System (INIS)

    We present details of the new electron holographic dark-field technique (HoloDark) for mapping strain in nanostructures. A diffracted beam emanating from an unstrained region of crystal is interfered (with the aid of an electrostatic biprism) with a diffracted beam from the strained region of interest. Geometric phase analysis (GPA) of the holographic fringes determines the relative deformation of the two crystalline lattices. Strain can be measured to high precision, with nanometre spatial resolution and for micron fields of view. Experiments are carried out on the SACTEM-Toulouse, a Tecnai F20 (FEI) equipped with imaging aberration corrector (CEOS), field-emission gun and rotatable biprism (FEI). We operate the microscope in free-lens control with the main objective lens switched off and using the corrector transfer lenses as a Lorentz lens. We will present measurements of strain in test nanostructures and show how artefacts from thickness variations can be removed. Finally, we show our first results using a recently developed aberration-corrected Lorentz mode (CEOS).

  18. Three-dimensional characteristics of alveolar macrophages in vitro observed by dark field microscopy

    Science.gov (United States)

    Swarat, Dominic; Wiemann, Martin; Lipinski, Hans-Gerd

    2014-05-01

    Alveolar macrophages (AM) are cells from immune defense inside the lung. They engulf particles in vacuoles from the outer membrane. Volume and surface are important parameters to characterize the particle uptake. AM change their shape within a few seconds, therefore it is hard to obtain by confocal laser scanning microscopy, which is commonly used to generate 3D-images. So we used an intensified dark field microscopy (DFM) as an alternative method to generate contrast rich AM gray tone image slices used for 3D-reconstructions of AM cells by VTK software applications. From these 3D-reconstructions approximate volume and surface data of the AM were obtained and compared to values found in the literature. Finally, simple geometrical 3D-models of the AM were created and compared to real data. Averaged volume and surface data from the DFM images are close to values found in the literature. Furthermore, calculation of volume and surface data from DFM images could be done faster if simplified geometrical 3D-models of the cells were used.

  19. Correction method for influence of tissue scattering for sidestream dark-field oximetry using multicolor LEDs

    Science.gov (United States)

    Kurata, Tomohiro; Oda, Shigeto; Kawahira, Hiroshi; Haneishi, Hideaki

    2016-10-01

    We have previously proposed an estimation method of intravascular oxygen saturation (SO_2) from the images obtained by sidestream dark-field (SDF) imaging (we call it SDF oximetry) and we investigated its fundamental characteristics by Monte Carlo simulation. In this paper, we propose a correction method for scattering by the tissue and performed experiments with turbid phantoms as well as Monte Carlo simulation experiments to investigate the influence of the tissue scattering in the SDF imaging. In the estimation method, we used modified extinction coefficients of hemoglobin called average extinction coefficients (AECs) to correct the influence from the bandwidth of the illumination sources, the imaging camera characteristics, and the tissue scattering. We estimate the scattering coefficient of the tissue from the maximum slope of pixel value profile along a line perpendicular to the blood vessel running direction in an SDF image and correct AECs using the scattering coefficient. To evaluate the proposed method, we developed a trial SDF probe to obtain three-band images by switching multicolor light-emitting diodes and obtained the image of turbid phantoms comprised of agar powder, fat emulsion, and bovine blood-filled glass tubes. As a result, we found that the increase of scattering by the phantom body brought about the decrease of the AECs. The experimental results showed that the use of suitable values for AECs led to more accurate SO_2 estimation. We also confirmed the validity of the proposed correction method to improve the accuracy of the SO_2 estimation.

  20. High energy X-ray phase and dark-field imaging using a random absorption mask.

    Science.gov (United States)

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-01-01

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science. PMID:27466217

  1. Development of X-ray dark-field imaging towards clinical application

    Institute of Scientific and Technical Information of China (English)

    ANDO Masami; RUBENSTEIN Edward; ROBERSON Joseph; SHIMAO Daisuke; SUGIYAMA Hiroshi; TAKEDA Ken; UENO Ei; WADA Hiroshi; HASHIMOTO Eiko; HASHIZUME Hiroyuki; HYODO Kazuyuki; INOUE Hajime; ISHIKAWA Tetsuya; KUNISADA Toshiyuki; MAKSIMENKO Anton; PATTANASIRIWISAWA Wanwisa

    2004-01-01

    Review of X-ray dark-field imaging under development is presented. Its goal is its application to clinical diagnosis of organs that have been invisible by the ordinary techniques. In order to clinically visualize tissues in detail one needs high contrast and high spatial resolution say ~50 μm. This X-ray optics comprises a Bragg asymmetric monochro-collimator and a Bragg case or a Laue case filter with capability of analyzing angle in a parallel position. Their diffraction index is 4,4,0 and the X-ray energy 35 keV (λ= 0.0354 nm). The filter has 0.6 mm thickness in the Bragg case or 1.075 mm or 2.15 mm thickness in the Laue case. Under this condition only the refracted X-rays from object can transmit through the filter while the beam that may receive absorption and/or phase change will not. Soft tissues at human joints thus taken show high contrast images so that the DFI is promising for clinical diagnosis. Preliminary X-ray absorption images of another clinical candidates of ear bones are also shown.

  2. A Pilot Search for Population III Supernova Candidates in the Spitzer/IRAC Dark Field

    CERN Document Server

    Frost, Mark I; Moustakas, Leonidas A; Krick, Jessica

    2009-01-01

    We have undertaken a systematic search for candidate supernovae from high-redshift Population III stars in a field that has been observed with repeated imaging on a cadence of 2-3 weeks over a 2.2 year baseline, the Spitzer/IRAC Dark Field. The individual epochs reach a typical 5-sigma depth of 1 uJy in IRAC Channel 1 (3.6 um). Requiring a minimum of four epochs coverage, the total effective area searched is 214 sq arcminutes. The unprecedented depth and multi-epochal nature of these data make it ideal for a first foray to detect transient objects which may be candidate luminous Pair Instability Supernovae from the primordial-metallicity first stars. The search was conducted over a broad range of timescales, allowing for different durations of the putative candidates' light curve plateau phases. All candidates were vetted by inspection of the Spitzer imaging data, as well as deep HST/ACS F814W imaging available over the full field. While many resolved-source objects were found with Spitzer variability, no tra...

  3. X-ray dark field imaging of human articular cartilage: Possible clinical application to orthopedic surgery

    International Nuclear Information System (INIS)

    Despite its convenience and non-invasiveness on daily clinical use, standard X-ray radiography cannot show articular cartilage. We developed a novel type of X-ray dark field imaging (DFI), which forms images only by a refracted beam with very low background illumination. We examined a disarticulated distal femur and a shoulder joint with surrounding soft tissue and skin, both excised from a human cadaver at the BL20B2 synchrotron beamline at SPring-8. The field was 90 mm wide and 90 mm high. Articular cartilage of the disarticulated distal femur was obvious on DFI, but not on standard X-ray images. Furthermore, DFI allowed visualization in situ of articular cartilage of the shoulder while covered with soft tissue and skin. The gross appearance of the articular cartilage on the dissected section of the proximal humerus was identical to the cartilage shown on the DFI image. These results suggested that DFI could provide a clinically accurate method of assessing articular cartilage. Hence, DFI would be a useful imaging tool for diagnosing joint disease such as osteoarthritis

  4. Refractive-index based tomosynthesis using dark-field imaging optics

    International Nuclear Information System (INIS)

    Tomosynthesis (TS) is a pseudo-3-dimensional image reconstruction method to recover depth-resolved information using restricted number of projections. In this research, refraction index based TS imaging using dark-field imaging (DFI) optics is proposed and biomedical soft tissues were imaged in low dose exposure. By a single exposure of an object, two projected images are obtained from a Laue-case analyzer of DFI. Calculating the both images refraction component is deduced, while two exposures are needed in DEI (diffraction enhanced imaging). Thus the measurement time and the radiation dose in DFI are half of DEI. In addition, the proposed reconstruction algorithm, derived from the quantitative relationship in measurement process, allows high contrast tomographic imaging in spite of one order smaller number of projections for CT (computed tomography). To demonstrate the proposed imaging protocol efficacy, an ex-vivo excised tissue of human lung were imaged using a system constructed at the vertical wiggler beamline at PF-BL14C at KEK. TS image is successfully delineated high quality soft tissue structures comparable to CT.

  5. Dynamical effects in strain measurements by dark-field electron holography

    Energy Technology Data Exchange (ETDEWEB)

    Javon, E. [CEMES-CNRS and Université de Toulouse, 29 rue Jeanne Marvig, F-31055 Toulouse (France); EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Lubk, A. [CEMES-CNRS and Université de Toulouse, 29 rue Jeanne Marvig, F-31055 Toulouse (France); EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Institute of Structure Physics, Technische Universität Dresden, 01062 Dresden (Germany); Cours, R. [CEMES-CNRS and Université de Toulouse, 29 rue Jeanne Marvig, F-31055 Toulouse (France); Reboh, S. [CEMES-CNRS and Université de Toulouse, 29 rue Jeanne Marvig, F-31055 Toulouse (France); CEA, LETI, Minatec Campus, 17 rue de Martyrs, 38054 Grenoble (France); Cherkashin, N.; Houdellier, F.; Gatel, C.; Hÿtch, M.J. [CEMES-CNRS and Université de Toulouse, 29 rue Jeanne Marvig, F-31055 Toulouse (France)

    2014-12-15

    Here, we study the effect of dynamic scattering on the projected geometric phase and strain maps reconstructed using dark-field electron holography (DFEH) for non-uniformly strained crystals. The investigated structure consists of a {SiGe/Si} superlattice grown on a (001)-Si substrate. The three-dimensional strain field within the thin TEM lamella is modelled by the finite element method. The observed projected strain is simulated in two ways by multiplying the strain at each depth in the crystal by a weighting function determined from a recently developed analytical two-beam dynamical theory, and by simply taking the average value. We demonstrate that the experimental results need to be understood in terms of the dynamical theory and good agreement is found between the experimental and simulated results. Discrepancies do remain for certain cases and are likely to be from an imprecision in the actual two-beam diffraction conditions, notably the deviation parameter, and points to limitations in the 2-beam approximation. Finally, a route towards a 3D reconstruction of strain fields is proposed. - Highlights: • We explain DFEH strain map thanks to a recent theoretical development. • The projection measured by DFEH is a weighted average of the strain along the e-beam. • The weighting function depends on diffracted beam, thickness and sample orientation. • The weighting functions were included in FEM simulation and compared to DFEH results. • Kinematic conditions avoid the dynamical effects and lead to the average strain value.

  6. High energy X-ray phase and dark-field imaging using a random absorption mask

    Science.gov (United States)

    Wang, Hongchang; Kashyap, Yogesh; Cai, Biao; Sawhney, Kawal

    2016-01-01

    High energy X-ray imaging has unique advantage over conventional X-ray imaging, since it enables higher penetration into materials with significantly reduced radiation damage. However, the absorption contrast in high energy region is considerably low due to the reduced X-ray absorption cross section for most materials. Even though the X-ray phase and dark-field imaging techniques can provide substantially increased contrast and complementary information, fabricating dedicated optics for high energies still remain a challenge. To address this issue, we present an alternative X-ray imaging approach to produce transmission, phase and scattering signals at high X-ray energies by using a random absorption mask. Importantly, in addition to the synchrotron radiation source, this approach has been demonstrated for practical imaging application with a laboratory-based microfocus X-ray source. This new imaging method could be potentially useful for studying thick samples or heavy materials for advanced research in materials science. PMID:27466217

  7. Dark-field electron holography for the mapping of strain in nanostructures: correcting artefacts and aberrations

    Energy Technology Data Exchange (ETDEWEB)

    Hytch, M J; Houdellier, F; Snoeck, E; Huee, F, E-mail: hytch@cemes.f [CEMES-CNRS, 29 rue Jeanne Marvig, 31055 Toulouse (France)

    2010-07-01

    We present details of the new electron holographic dark-field technique (HoloDark) for mapping strain in nanostructures. A diffracted beam emanating from an unstrained region of crystal is interfered (with the aid of an electrostatic biprism) with a diffracted beam from the strained region of interest. Geometric phase analysis (GPA) of the holographic fringes determines the relative deformation of the two crystalline lattices. Strain can be measured to high precision, with nanometre spatial resolution and for micron fields of view. Experiments are carried out on the SACTEM-Toulouse, a Tecnai F20 (FEI) equipped with imaging aberration corrector (CEOS), field-emission gun and rotatable biprism (FEI). We operate the microscope in free-lens control with the main objective lens switched off and using the corrector transfer lenses as a Lorentz lens. We will present measurements of strain in test nanostructures and show how artefacts from thickness variations can be removed. Finally, we show our first results using a recently developed aberration-corrected Lorentz mode (CEOS).

  8. CFD Simulation of Annular Centrifugal Extractors

    OpenAIRE

    Vedantam, S.; Wardle, K. E.; Tamhane, T. V.; Ranade, V. V.; Joshi, J. B.

    2012-01-01

    Annular centrifugal extractors (ACE), also called annular centrifugal contactors offer several advantages over the other conventional process equipment such as low hold-up, high process throughput, low residence time, low solvent inventory and high turn down ratio. The equipment provides a very high value of mass transfer coefficient and interfacial area in the annular zone because of the high level of power consumption per unit volume and separation inside the rotor due to the high g of cent...

  9. Psoriatic Arthritis with Annular Pustular Psoriasis.

    Science.gov (United States)

    Nagafuchi, Hiroko; Watanabe, Kyoko; Mikage, Hidenori; Ozaki, Shoichi

    2016-01-01

    We herein present the case of a 56-year-old woman who presented with symptoms of psoriatic arthritis (PsA) with erythema that progressed to annular pustular psoriasis. The patient had a 15-year history of polyarthritis. Annular pustular psoriasis is not typically observed in cases of arthritis. This is the first reported case of PsA with annular pustular psoriasis. PMID:26935375

  10. Improvement of Sidestream Dark Field Imaging with an Image Acquisition Stabilizer

    Directory of Open Access Journals (Sweden)

    Sjauw Krishan D

    2010-07-01

    Full Text Available Abstract Background In the present study we developed, evaluated in volunteers, and clinically validated an image acquisition stabilizer (IAS for Sidestream Dark Field (SDF imaging. Methods The IAS is a stainless steel sterilizable ring which fits around the SDF probe tip. The IAS creates adhesion to the imaged tissue by application of negative pressure. The effects of the IAS on the sublingual microcirculatory flow velocities, the force required to induce pressure artifacts (PA, the time to acquire a stable image, and the duration of stable imaging were assessed in healthy volunteers. To demonstrate the clinical applicability of the SDF setup in combination with the IAS, simultaneous bilateral sublingual imaging of the microcirculation were performed during a lung recruitment maneuver (LRM in mechanically ventilated critically ill patients. One SDF device was operated handheld; the second was fitted with the IAS and held in position by a mechanic arm. Lateral drift, number of losses of image stability and duration of stable imaging of the two methods were compared. Results Five healthy volunteers were studied. The IAS did not affect microcirculatory flow velocities. A significantly greater force had to applied onto the tissue to induced PA with compared to without IAS (0.25 ± 0.15 N without vs. 0.62 ± 0.05 N with the IAS, p Conclusions The present study has validated the use of an IAS for improvement of SDF imaging by demonstrating that the IAS did not affect microcirculatory perfusion in the microscopic field of view. The IAS improved both axial and lateral SDF image stability and thereby increased the critical force required to induce pressure artifacts. The IAS ensured a significantly increased duration of maintaining a stable image sequence.

  11. Systematic comparison of the use of annular and Zernike circle polynomials for annular wavefronts

    NARCIS (Netherlands)

    Mahajan, V.N.; Aftab, M.

    2010-01-01

    The theory of wavefront analysis of a noncircular wavefront is given and applied for a systematic comparison of the use of annular and Zernike circle polynomials for the analysis of an annular wavefront. It is shown that, unlike the annular coefficients, the circle coefficients generally change as t

  12. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-04-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  13. Confocal Annular Josephson Tunnel Junctions

    Science.gov (United States)

    Monaco, Roberto

    2016-09-01

    The physics of Josephson tunnel junctions drastically depends on their geometrical configurations and here we show that also tiny geometrical details play a determinant role. More specifically, we develop the theory of short and long annular Josephson tunnel junctions delimited by two confocal ellipses. The behavior of a circular annular Josephson tunnel junction is then seen to be simply a special case of the above result. For junctions having a normalized perimeter less than one, the threshold curves in the presence of an in-plane magnetic field of arbitrary orientations are derived and computed even in the case with trapped Josephson vortices. For longer junctions, a numerical analysis is carried out after the derivation of the appropriate motion equation for the Josephson phase. We found that the system is modeled by a modified and perturbed sine-Gordon equation with a space-dependent effective Josephson penetration length inversely proportional to the local junction width. Both the fluxon statics and dynamics are deeply affected by the non-uniform annulus width. Static zero-field multiple-fluxon solutions exist even in the presence of a large bias current. The tangential velocity of a traveling fluxon is not determined by the balance between the driving and drag forces due to the dissipative losses. Furthermore, the fluxon motion is characterized by a strong radial inward acceleration which causes electromagnetic radiation concentrated at the ellipse equatorial points.

  14. Bistability and hysteresis of annular impinging jets

    Science.gov (United States)

    Tisovsky, Tomas

    2016-06-01

    In present study, the bistability and hysteresis of annular impinging jets is investigated. Annular impinging jets are simulated using open source CFD code - OpenFOAM. Both flow field patterns of interest are obtained and hysteresis is found by means of dynamic mesh simulation. Effect of nozzle exit velocity on resulting hysteresis loop is also illustrated.

  15. Soliton bunching in annular Josephson junctions

    DEFF Research Database (Denmark)

    Vernik, I.V; Lazarides, Nickos; Sørensen, Mads Peter;

    1996-01-01

    By studying soliton (fluxon) motion in long annular Josephson junctions it is possible to avoid the influence of the boundaries and soliton-soliton collisions present in linear junctions. A new experimental design consisting of a niobium coil placed on top of an annular junction has been used...

  16. Optimum annular focusing by a phase plate

    CERN Document Server

    Arrizón, Victor; Aguirre-Olivas, Dilia; Mellado-Villaseñor, Gabriel

    2015-01-01

    Conventional light focusing, i. e. concentration of an extended optical field within a small area around a point, is a frequently used process in Optics. An important extension to conventional focusing is the generation of the annular focal field of an optical beam. We discuss a simple optical setup that achieves this kind of focusing employing a phase plate as unique optical component. We first establish the class of beams that being transmitted through the phase plate can be focused into an annular field with topological charge of arbitrary integer order q. Then, for each beam in this class we determine the plate transmittance that generates the focal field with the maximum possible peak intensity. In particular, we discuss and implement experimentally the optimum annular focusing of a Gaussian beam. The attributes of optimum annular focal fields, namely the high peak intensity, intensity gradient and narrow annular section, are advantageous for different applications of such structured fields.

  17. [Generalized granuloma annulare or diffuse dermal histiocytosis?].

    Science.gov (United States)

    Kretzschmar, L; Biel, K; Luger, T A; Goerdt, S

    1995-08-01

    Generalized granuloma annulare is a rare variant of granuloma annulare affecting the trunk and extremities with a multitude of lesions. In contrast to localized granuloma annulare, generalized granuloma annulare occurs in older patients, shows a stronger association with diabetes, and is characteristically chronic. Like our 55-year-old patient, most patients present with papules and annular plaques; less often, macular or non-annular lesions may be encountered. Histology often fails to show necrobiotic or necrotic connective tissue changes demarcated by a palisading granuloma. Instead, there are diffuse dermal, band-like or nodular aggregations of histiocytes intermingled with some multinucleated giant cells and a predominantly lymphocytic infiltrate in the periphery. Because of its special characteristics, it has been suggested that generalized granuloma annulare might constitute a separate disease entity and that it should be classed among the primary cutaneous histiocytoses as a diffuse dermal histiocytosis. Using immunohistochemistry to determine the macrophage phenotype of the lesional histiocytes, we have shown that generalized granuloma annulare is not a cutaneous histiocytosis. Neither MS-1 high-molecular-weight protein, a new specific marker for cutaneous non-Langerhans cell histiocytoses, nor CD1a, the well-known marker for Langerhans cells and Langerhans cell histiocytoses, is expressed by the lesional histiocytes of our patient. In contrast, the antigen expression pattern was diagnostic for non-infectious granulomas and was highly similar to that in localized granuloma annulare. In contrast to the successful treatment of localized granuloma annulare reported with intralesional interferon beta-1, systemic treatment with interferon alpha-2b (9 x 10(6) units three times a week) was ineffective.

  18. Structural characterization of Pt–Pd core–shell nanoparticles by Cs-corrected STEM

    International Nuclear Information System (INIS)

    Pt–Pd core–shell nanoparticles were synthesized using a modified polyol method. A thermal method under refluxing, carrying on the reaction up to 285 °C, has been performed to reduce metallic salts using ethylene glycol as reducer and poly(N-vinyl-2-pyrrolidone) as protective reagent of the formed bimetallic nanoparticles. According to other works, this type of structure has been studied and utilized to successfully increase the catalytic properties of monometallic nanoparticles Pt or Pd. Core–shell bimetallic nanoparticles were structurally characterized using aberration-corrected scanning transmission electron microscopy (Cs-STEM) equipped with a high-angle annular dark field detector, energy-dispersive X-ray spectrometry (EDS), and electron energy-loss spectroscopy (EELS). The high-resolution elemental line scan and mappings were carried out using a combination of STEM–EDS and STEM–EELS. The obtained results show the growth of the Pd shell on the Pt core with polyhedral morphology. The average size of the bimetallic nanoparticles was 13.5 nm and the average size of the core was 8.5 nm; consequently, the thickness of the shell was around 2.5 nm. The growth of the Pd shell on the Pt core is layer by layer, suggesting a Frank-van der Merwe growth mechanism.

  19. Correction of non-linear thickness effects in HAADF STEM electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Van den Broek, W., E-mail: wouter.vandenbroek@uni-ulm.de [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Rosenauer, A. [Institut fuer Festkoerperphysik (IFP), Universitaet Bremen, Otto-Hahn-Allee 1, 28359 Bremen (Germany); Goris, B.; Martinez, G.T.; Bals, S.; Van Aert, S.; Van Dyck, D. [Electron Microscopy for Materials Science (EMAT), University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium)

    2012-05-15

    In materials science, high angle annular dark field scanning transmission electron microscopy is often used for tomography at the nanometer scale. In this work, it is shown that a thickness dependent, non-linear damping of the recorded intensities occurs. This results in an underestimated intensity in the interior of reconstructions of homogeneous particles, which is known as the cupping artifact. In this paper, this non-linear effect is demonstrated in experimental images taken under common conditions and is reproduced with a numerical simulation. Furthermore, an analytical derivation shows that these non-linearities can be inverted if the imaging is done quantitatively, thus preventing cupping in the reconstruction. -- Highlights: Black-Right-Pointing-Pointer In HAADF STEM, a thickness dependent, non-linear damping of the projected intensities occurs. Black-Right-Pointing-Pointer In tomography, this leads to underestimated intensities in the interior of homogeneous particles, the cupping artifact. Black-Right-Pointing-Pointer The non-linear damping is demonstrated in experimental images and reproduced with numerical simulations. Black-Right-Pointing-Pointer The non-linear damping can be undone if the imaging is done quantitatively. Black-Right-Pointing-Pointer Experimental proof is provided showing that cupping can be prevented.

  20. STEM nanoanalysis of Au/Pt/Ti-Si3N4 interfacial defects and reactions during local stress of SiGe HBTs

    Science.gov (United States)

    Alaeddine, Ali; Genevois, Cécile; Chevalier, Laurence; Daoud, Kaouther

    2011-10-01

    A new insight on the behavior of metal contact-insulating interfaces in SiGe heterojunction bipolar transistor is given by high-performance aberration-corrected scanning transmission electron microscopy (STEM) analysis tools equipped with sub-nanometric probe size. It is demonstrated that the presence of initial defects introduced during technological processes play a major role in the acceleration of degradation mechanisms of the structure during stress. A combination of energy-filtered transmission electron microscopy analysis with high angle annular dark field STEM and energy dispersive spectroscopy provides strong evidence that migration of Au-Pt from the metal contacts to Ti/Si3N4 interface is one of the precursors to species interdiffusion and reactions. High current densities and related local heating effects induce the evolution of the pure Ti initial layer into mixture layer composed of Ti, O, and N. Local contamination of Ti layers by fluorine atoms is also pointed out, as well as rupture of TiN thin barrier layer.

  1. STEM nanoanalysis of Au/Pt/Ti-Si3N4 interfacial defects and reactions during local stress of SiGe HBTs

    Directory of Open Access Journals (Sweden)

    Alaeddine Ali

    2011-01-01

    Full Text Available Abstract A new insight on the behavior of metal contact-insulating interfaces in SiGe heterojunction bipolar transistor is given by high-performance aberration-corrected scanning transmission electron microscopy (STEM analysis tools equipped with sub-nanometric probe size. It is demonstrated that the presence of initial defects introduced during technological processes play a major role in the acceleration of degradation mechanisms of the structure during stress. A combination of energy-filtered transmission electron microscopy analysis with high angle annular dark field STEM and energy dispersive spectroscopy provides strong evidence that migration of Au-Pt from the metal contacts to Ti/Si3N4 interface is one of the precursors to species interdiffusion and reactions. High current densities and related local heating effects induce the evolution of the pure Ti initial layer into mixture layer composed of Ti, O, and N. Local contamination of Ti layers by fluorine atoms is also pointed out, as well as rupture of TiN thin barrier layer.

  2. HAADF-STEM atom counting in atom probe tomography specimens: Towards quantitative correlative microscopy.

    Science.gov (United States)

    Lefebvre, W; Hernandez-Maldonado, D; Moyon, F; Cuvilly, F; Vaudolon, C; Shinde, D; Vurpillot, F

    2015-12-01

    The geometry of atom probe tomography tips strongly differs from standard scanning transmission electron microscopy foils. Whereas the later are rather flat and thin (atom probe tomography specimens. Based on simulations (electron probe propagation and image simulations), the possibility to apply quantitative high angle annular dark field scanning transmission electron microscopy to of atom probe tomography specimens has been tested. The influence of electron probe convergence and the benefice of deconvolution of electron probe point spread function electron have been established. Atom counting in atom probe tomography specimens is for the first time reported in this present work. It is demonstrated that, based on single projections of high angle annular dark field imaging, significant quantitative information can be used as additional input for refining the data obtained by correlative analysis of the specimen in APT, therefore opening new perspectives in the field of atomic scale tomography.

  3. Etizolam-induced superficial erythema annulare centrifugum.

    Science.gov (United States)

    Kuroda, K; Yabunami, H; Hisanaga, Y

    2002-01-01

    Erythema annulare centrifugum (EAC) is characterized by slowly enlarging annular erythematous lesions. Although the origin is not clear in most cases, EAC has been associated with infections, medications, and in rare cases, underlying malignancy. We describe a patient who developed annular erythematous lesions after etizolam administration. The eruptions were typical of the superficial form of EAC, both clinically and histopathologically. The lesions disappeared shortly after discontinuation of the medication. Patch testing with etizolam gave positive results. To our knowledge this is the first reported case of etizolam-induced superficial EAC. PMID:11952667

  4. Real-time scattered light dark-field microscopic imaging of the dynamic degradation process of sodium dimethyldithiocarbamate

    Science.gov (United States)

    Lei, Gang; Gao, Peng Fei; Liu, Hui; Huang, Cheng Zhi

    2015-12-01

    Single nanoparticle analysis (SNA) technique with the aid of a dark-field microscopic imaging (iDFM) technique has attracted wide attention owing to its high sensitivity. Considering that the degradation of pesticides can bring about serious problems in food and the environment, and that the real-time monitoring of the dynamic degradation process of pesticides can help understand and define their degradation mechanisms, herein we real-time monitored the decomposition dynamics of sodium dimethyldithiocarbamate (NaDDC) under neutral and alkaline conditions by imaging single silver nanoparticles (AgNPs) under a dark-field microscope (DFM); the localized surface plasmon resonance (LSPR) scattering signals were measured at a single nanoparticle level. As a result, the chemical mechanism of the degradation of NaDDC under neutral and alkaline conditions was proposed, and the inhibition effects of metal ions including Zn(ii) and Cu(ii) were investigated in order to understand the decomposition process in different environments. It was found that Cu(ii) forms the most stable complex with NaDDC with a stoichiometric ratio of 1 : 2, which greatly reduces the toxicity.Single nanoparticle analysis (SNA) technique with the aid of a dark-field microscopic imaging (iDFM) technique has attracted wide attention owing to its high sensitivity. Considering that the degradation of pesticides can bring about serious problems in food and the environment, and that the real-time monitoring of the dynamic degradation process of pesticides can help understand and define their degradation mechanisms, herein we real-time monitored the decomposition dynamics of sodium dimethyldithiocarbamate (NaDDC) under neutral and alkaline conditions by imaging single silver nanoparticles (AgNPs) under a dark-field microscope (DFM); the localized surface plasmon resonance (LSPR) scattering signals were measured at a single nanoparticle level. As a result, the chemical mechanism of the degradation of Na

  5. Divergent Field Annular Ion Engine Project

    Data.gov (United States)

    National Aeronautics and Space Administration — The proposed work investigates an approach that would allow an annular ion engine geometry to achieve ion beam currents approaching the Child-Langmuir limit. In...

  6. A clinical study of annular cyclitis

    Directory of Open Access Journals (Sweden)

    Marilita Michael Moschos

    2009-02-01

    Full Text Available Marilita Michael Moschos1, Yan Guex-Crosier2, Ioannis Margetis1, Leonidas Zografos21Department of Ophthalmology, University of Athens, Greece; 2Jules Gonin Eye Hospital, University of Lausanne, SwitzerlandPurpose: To investigate six cases of annular cyclitis.Methods: All patients with impairment of visual acuity underwent complete ophthalmologic examination, color fundus photography, laboratory tests and fluorescein angiography. Indocyanine green (ICG angiography and B-scan ultrasonography were also performed in three cases in order to diagnose the disease.Results: All patients presented a unilateral or bilateral granulomatous uveitis, associated with inflammatory annular cyclitis. They had a shallow anterior chamber, a mildly elevated intraocular pressure (under 25 mm Hg and an annular serous retinal detachment. A resolution was observed after specific therapy associated with systemic prednisolone therapy and antiglaucomatous drops.Conclusion: This is the first description of an observational study of six patients with inflammatory annular cyclitis.Keywords: cyclitis, uveitis, malignant glaucoma

  7. Adaptive optics scanning ophthalmoscopy with annular pupils.

    Science.gov (United States)

    Sulai, Yusufu N; Dubra, Alfredo

    2012-07-01

    Annular apodization of the illumination and/or imaging pupils of an adaptive optics scanning light ophthalmoscope (AOSLO) for improving transverse resolution was evaluated using three different normalized inner radii (0.26, 0.39 and 0.52). In vivo imaging of the human photoreceptor mosaic at 0.5 and 10° from fixation indicates that the use of an annular illumination pupil and a circular imaging pupil provides the most benefit of all configurations when using a one Airy disk diameter pinhole, in agreement with the paraxial confocal microscopy theory. Annular illumination pupils with 0.26 and 0.39 normalized inner radii performed best in terms of the narrowing of the autocorrelation central lobe (between 7 and 12%), and the increase in manual and automated photoreceptor counts (8 to 20% more cones and 11 to 29% more rods). It was observed that the use of annular pupils with large inner radii can result in multi-modal cone photoreceptor intensity profiles. The effect of the annular masks on the average photoreceptor intensity is consistent with the Stiles-Crawford effect (SCE). This indicates that combinations of images of the same photoreceptors with different apodization configurations and/or annular masks can be used to distinguish cones from rods, even when the former have complex multi-modal intensity profiles. In addition to narrowing the point spread function transversally, the use of annular apodizing masks also elongates it axially, a fact that can be used for extending the depth of focus of techniques such as adaptive optics optical coherence tomography (AOOCT). Finally, the positive results from this work suggest that annular pupil apodization could be used in refractive or catadioptric adaptive optics ophthalmoscopes to mitigate undesired back-reflections.

  8. Comparative morphology analysis of live blood platelets using scanning ion conductance and robotic dark-field microscopy.

    Science.gov (United States)

    Kraus, Max-Joseph; Seifert, Jan; Strasser, Erwin F; Gawaz, Meinrad; Schäffer, Tilman E; Rheinlaender, Johannes

    2016-09-01

    Many conventional microscopy techniques for investigating platelet morphology such as electron or fluorescence microscopy require highly invasive treatment of the platelets such as fixation, drying and metal coating or staining. Here, we present two unique but entirely different microscopy techniques for direct morphology analysis of live, unstained platelets: scanning ion conductance microscopy (SICM) and robotic dark-field microscopy (RDM). We demonstrate that both techniques allow for a quantitative evaluation of the morphological features of live adherent platelets. We show that their morphology can be quantified by both techniques using the same geometric parameters and therefore can be directly compared. By imaging the same identical platelets subsequently with SICM and RDM, we found that area, perimeter and circularity of the platelets are directly correlated between SICM and dark-field microscopy (DM), while the fractal dimension (FD) differed between the two microscopy techniques. We show that SICM and RDM are both valuable tools for the ex vivo investigation of the morphology of live platelets, which might contribute to new insights into the physiological and pathophysiological role of platelet spreading. PMID:27063564

  9. On the origin and nature of the grating interferometric dark-field contrast obtained with low-brilliance x-ray sources

    Science.gov (United States)

    Koenig, Thomas; Zuber, Marcus; Trimborn, Barbara; Farago, Tomas; Meyer, Pascal; Kunka, Danays; Albrecht, Frederic; Kreuer, Sascha; Volk, Thomas; Fiederle, Michael; Baumbach, Tilo

    2016-05-01

    The x-ray dark-field contrast accessible via grating interferometry is sensitive to features at length scales well below what is resolvable by a detector system. It is commonly explained as arising from small-angle x-ray scattering (SAXS), and can be implemented both at synchrotron beamlines and with low-brilliance sources such as x-ray tubes. Here, we demonstrate that for tube based setups the underlying process of image formation can be fundamentally different. For focal spots or detector pixels that comprise multiple grating periods, we show that dark-field images contain a strong artificial and system-specific component not arising from SAXS. Based on experiments carried out with a nanofocus x-ray tube and the example of an excised rat lung, we demonstrate that the dark-field contrast observed for porous media transforms into a differential phase contrast for large geometric magnifications. Using a photon counting detector with an adjustable point spread function, we confirm that a dark-field image can indeed be formed by an intra-pixel differential phase contrast that cannot be resolved as such due to a dephasing between the periodicities of the absorption grating and the Talbot carpet. Our findings are further corroborated by a link between the strength of this pseudo-dark-field contrast and our x-ray tube’s focal spot size in a three-grating setup. These results must not be ignored when measurements are intended to be reproducible across systems.

  10. An in-house developed annular bright field detection system

    International Nuclear Information System (INIS)

    Annular bright field (ABF) detectors have been developed in the last few years allowing the direct imaging of low-Z atoms from oxygen down to hydrogen. These types of detectors are now available as standard attachments for the latest generation of top-end electron microscopes. However these systems cannot always be installed in previous generation microscopes. In this paper we report the preliminary results of an in-house implementation of a ABF detection system on a CEOS aberration corrected JEOL 2200FS STEM. This has been obtained by exploiting the standard BF detector coupled with a high vacuum compatible, X-ray tight and retractable shadowing mechanism. This results in the acquisition of near zero-angle scattered electrons with inner collection semi-angle from 2.0 mrad to 23 mrad and outer semi-angle in the range from 3.0 mrad to 35 mrad. The characteristics and performances of this ABF detection system are discussed

  11. CFD Simulation of Annular Centrifugal Extractors

    Directory of Open Access Journals (Sweden)

    S. Vedantam

    2012-01-01

    Full Text Available Annular centrifugal extractors (ACE, also called annular centrifugal contactors offer several advantages over the other conventional process equipment such as low hold-up, high process throughput, low residence time, low solvent inventory and high turn down ratio. The equipment provides a very high value of mass transfer coefficient and interfacial area in the annular zone because of the high level of power consumption per unit volume and separation inside the rotor due to the high g of centrifugal field. For the development of rational and reliable design procedures, it is important to understand the flow patterns in the mixer and settler zones. Computational Fluid Dynamics (CFD has played a major role in the constant evolution and improvements of this device. During the past thirty years, a large number of investigators have undertaken CFD simulations. All these publications have been carefully and critically analyzed and a coherent picture of the present status has been presented in this review paper. Initially, review of the single phase studies in the annular region has been presented, followed by the separator region. In continuation, the two-phase CFD simulations involving liquid-liquid and gas-liquid flow in the annular as well as separator regions have been reviewed. Suggestions have been made for the future work for bridging the existing knowledge gaps. In particular, emphasis has been given to the application of CFD simulations for the design of this equipment.

  12. Simulations of x-ray speckle-based dark-field and phase-contrast imaging with a polychromatic beam

    International Nuclear Information System (INIS)

    Following the first experimental demonstration of x-ray speckle-based multimodal imaging using a polychromatic beam [I. Zanette et al., Phys. Rev. Lett. 112(25), 253903 (2014)], we present a simulation study on the effects of a polychromatic x-ray spectrum on the performance of this technique. We observe that the contrast of the near-field speckles is only mildly influenced by the bandwidth of the energy spectrum. Moreover, using a homogeneous object with simple geometry, we characterize the beam hardening artifacts in the reconstructed transmission and refraction angle images, and we describe how the beam hardening also affects the dark-field signal provided by speckle tracking. This study is particularly important for further implementations and developments of coherent speckle-based techniques at laboratory x-ray sources

  13. Simulations of x-ray speckle-based dark-field and phase-contrast imaging with a polychromatic beam

    Energy Technology Data Exchange (ETDEWEB)

    Zdora, Marie-Christine, E-mail: marie-christine.zdora@diamond.ac.uk [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom); Department of Physics & Astronomy, University College London, London WC1E 6BT (United Kingdom); Thibault, Pierre [Department of Physics & Astronomy, University College London, London WC1E 6BT (United Kingdom); Pfeiffer, Franz [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Zanette, Irene [Lehrstuhl für Biomedizinische Physik, Physik-Department & Institut für Medizintechnik, Technische Universität München, 85748 Garching (Germany); Diamond Light Source, Harwell Science and Innovation Campus, Didcot, Oxfordshire OX11 0DE (United Kingdom)

    2015-09-21

    Following the first experimental demonstration of x-ray speckle-based multimodal imaging using a polychromatic beam [I. Zanette et al., Phys. Rev. Lett. 112(25), 253903 (2014)], we present a simulation study on the effects of a polychromatic x-ray spectrum on the performance of this technique. We observe that the contrast of the near-field speckles is only mildly influenced by the bandwidth of the energy spectrum. Moreover, using a homogeneous object with simple geometry, we characterize the beam hardening artifacts in the reconstructed transmission and refraction angle images, and we describe how the beam hardening also affects the dark-field signal provided by speckle tracking. This study is particularly important for further implementations and developments of coherent speckle-based techniques at laboratory x-ray sources.

  14. Electrokinetic Evaluation of Individual Exosomes by On-Chip Microcapillary Electrophoresis with Laser Dark-Field Microscopy

    Science.gov (United States)

    Kato, Kei; Kobayashi, Masashi; Hanamura, Nami; Akagi, Takanori; Kosaka, Nobuyoshi; Ochiya, Takahiro; Ichiki, Takanori

    2013-06-01

    Cell-secreted nanovesicles called exosomes are expected as a promising candidate biomarker of various diseases. Toward the future application of exosomes as a disease biomarker for low-invasive diagnostics, challenges remain in the development of sensitive and precise analysis methods for exosomes. In this study, we performed the electrokinetic evaluation of individual exosomes by the combined use of on-chip microcapillary electrophoresis and laser dark-field microscopy. We extracted exosomes from six types of human cell cultured in a serum-free medium by differential ultracentrifugation and their zeta potential (electrophoretic mobility) were evaluated. We demonstrated that the proposed electrophoresis apparatus is particularly suitable for the tracking analysis of the electrophoretic migration of individual exosomes and enables the accurate evaluation of the zeta potential distribution of exosomes, for the first time. From the experimental results, we found that there is a strong correlation between the average zeta potentials of exosomes and their cells of origin.

  15. Complete polarization characterization of single plasmonic nanoparticle enabled by a novel Dark-field Mueller matrix spectroscopy system

    CERN Document Server

    Chandel, Shubham; Ray, Subir K; Das, Anwesh; Ghosh, Anirudha; Raj, Satyabrata; Ghosh, Nirmalya

    2015-01-01

    Information on the polarization properties of scattered light from plasmonic systems are of paramount importance due to fundamental interest and potential applications. However, such studies are severely compromised due to the experimental difficulties in recording full polarization response of plasmonic nanostructures. Here, we report on a novel Mueller matrix spectroscopic system capable of acquiring complete polarization information from single isolated plasmonic nanoparticle/nanostructure. The outstanding issues pertaining to reliable measurements of full 4X4 spectroscopic scattering Mueller matrices from single nanoparticle/nanostructures are overcome by integrating an efficient Mueller matrix measurement scheme and a robust calibration method with a dark-field microscopic spectroscopy arrangement.The spectral polarization responses of the required polarization state generator, analyzer units, the imaging and the detection systemsare taken care off by eigenvalue calibration, thus enabling recording of th...

  16. Impact of the phase defect structure on an actinic dark-field blank inspection signal and wafer printability

    Science.gov (United States)

    Amano, Tsuyoshi; Murachi, Tetsunori; Yamane, Takeshi; Arisawa, Yukiyasu; Terasawa, Tsuneo

    2012-03-01

    A variety of phase defects (PDs) such as programmed bump and pit PDs, and native bump and pit PDs were detected by a dark-field ABI (Actinic Blank Inspection) tool. Among the PDs, some of them seemed to grow and propagate in an angular direction, away from substrate surface as was found by a TEM analysis. This presentation reports on the influence of 3-D phase defect on wafer printability, and on defect detection signals of an ABI tool. The result shows that the impact of the inclination angle on printing performance was quite significant when the PDs were not covered with the absorber pattern. On the other hand, the defect detection signal intensity was negligibly small in the case where the inclination angle was less than 9 degrees. However, ABI with its high magnification optics can pinpoint the PD's actual location as defined by the EUV light, rather than the ones that are not so clearly define by the surface topography.

  17. Real-time dark-field scattering microscopic monitoring of the in situ growth of single Ag@Hg nanoalloys.

    Science.gov (United States)

    Liu, Yue; Huang, Cheng Zhi

    2013-12-23

    A comprehensive understanding of the growth mechanism of nanoalloys is beneficial in designing and synthesizing nanoalloys with precisely tailored properties to extend their applications. Herein, we present the investigation in this aspect by real-time monitoring of the in situ growth of single Ag@Hg nanoalloys, through direct amalgamation of Ag nanoparticles with elemental mercury, by dark-field scattering microscopy. Four typically shaped Ag nanoparticles, such as rods, triangular bipyramids, cubes, and spheres, were used as seeds for studying the growth of Ag@Hg nanoalloys. The scattered light of Ag nanoparticles of different shapes, on exposure to the growth solution, exhibited a noticeable blue-shift followed by a red-shift, suggesting the growth of Ag@Hg nanoalloys. The formation of Ag@Hg nanoalloys was confirmed by scanning electron microscopy, high-resolution transmit electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and elemental mapping and line scanning. Further analysis of the time-dependent spectral data and morphological change of single nanoparticles during the growth led to the visual identification of the growth mechanism of single Ag@Hg nanoalloys. Three important steps were involved: first, rapid adsorption of Hg atoms onto Ag nanoparticles; second, initial diffusion of Hg atoms into Ag nanoparticles, rounding or shortening the particles; third, further diffusion of Hg atoms leading to the formation of spherical Ag@Hg nanoalloys. On the basis of these results, Ag@Hg nanoalloys with given optical properties can be synthesized. Moreover, dark-field scattering microscopy is expected to be a powerful tool used for real-time monitoring of the in situ growth of other metal nanoparticles. PMID:24279755

  18. Annular bilayer magnetoelectric composites: theoretical analysis.

    Science.gov (United States)

    Guo, Mingsen; Dong, Shuxiang

    2010-01-01

    The laminated bilayer magnetoelectric (ME) composites consist of magnetostrictive and piezoelectric layers are known to have giant ME coefficient due to the high coupling efficiency in bending mode. In our previous report, the bar-shaped bilayer composite has been investigated by using a magnetoelectric-coupling equivalent circuit. Here, we propose an annular bilayer ME composite, which consists of magnetostrictive and piezoelectric rings. This composite has a much lower resonance frequency of bending mode compared with its radial mode. In addition, the annular bilayer ME composite is expected to respond to vortex magnetic field as well as unidirectional magnetic field. In this paper, we investigate the annular bilayer ME composite by using impedance-matrix method and predict the ME coefficients as a function of geometric parameters of the composites. PMID:20178914

  19. Stitching algorithm for annular subaperture interferometry

    Institute of Scientific and Technical Information of China (English)

    Xi Hou; Fan Wu; Li Yang; Shibin Wu; Qiang Chen

    2006-01-01

    @@ Annular subaperture interferometry (ASI) has been developed for low cost and flexible test of rotationally symmetric aspheric surfaces, in which accurately combining the subaperture measurement data corrupted by misalignments and noise into a complete surface figure is the key problem. By introducing the Zernike annular polynomials which are orthogonal over annulus, a method that eliminates the coupling problem in the earlier algorithm based on Zernike circle polynomials is proposed. Vector-matrix notation is used to simplify the description and calculations. The performance of this reduction method is evaluated by numerical simulation. The results prove this method with high precision and good anti-noise capability.

  20. Optimal Thrust Vectoring for an Annular Aerospike Nozzle Project

    Data.gov (United States)

    National Aeronautics and Space Administration — Recent success of an annular aerospike flight test by NASA Dryden has prompted keen interest in providing thrust vector capability to the annular aerospike nozzle...

  1. Azimuthally forced flames in an annular combustor

    Science.gov (United States)

    Worth, Nicholas; Dawson, James; Mastorakos, Epaminondas

    2015-11-01

    Thermoacoustic instabilities are more likely to occur in lean burn combustion systems, making their adoption both difficult and costly. At present, our knowledge of such phenomena is insufficient to produce an inherently stable combustor by design, and therefore an improved understanding of these instabilities has become the focus of a significant research effort. Recent experimental and numerical studies have demonstrated that the symmetry of annular chambers permit a range of self-excited azimuthal modes to be generated in annular geometry, which can make the study of isolated modes difficult. While acoustic forcing is common in single flame experiments, no equivalent for forced azimuthal modes in an annular chamber have been demonstrated. The present investigation focuses on the novel application of acoustic forcing to a laboratory scale annular combustor, in order to generate azimuthal standing wave modes at a prescribed frequency and amplitude. The results focus on the ability of the method to isolate the mode of oscillation using experimental pressure and high speed OH* measurements. The successful excitation of azimuthal modes demonstrated represents an important step towards improving our fundamental understanding of this phenomena in practically relevant geometry.

  2. Annular beam with segmented phase gradients

    Directory of Open Access Journals (Sweden)

    Shubo Cheng

    2016-08-01

    Full Text Available An annular beam with a single uniform-intensity ring and multiple segments of phase gradients is proposed in this paper. Different from the conventional superposed vortices, such as the modulated optical vortices and the collinear superposition of multiple orbital angular momentum modes, the designed annular beam has a doughnut intensity distribution whose radius is independent of the phase distribution of the beam in the imaging plane. The phase distribution along the circumference of the doughnut beam can be segmented with different phase gradients. Similar to a vortex beam, the annular beam can also exert torques and rotate a trapped particle owing to the orbital angular momentum of the beam. As the beam possesses different phase gradients, the rotation velocity of the trapped particle can be varied along the circumference. The simulation and experimental results show that an annular beam with three segments of different phase gradients can rotate particles with controlled velocities. The beam has potential applications in optical trapping and optical information processing.

  3. Fluxon Dynamics in Elliptic Annular Josephson Junctions

    DEFF Research Database (Denmark)

    Monaco, Roberto; Mygind, Jesper

    2016-01-01

    We analyze the dynamics of a magnetic flux quantum (current vortex) trapped in a current-biased long planar elliptic annular Josephson tunnel junction. The system is modeled by a perturbed sine-Gordon equation that determines the spatial and temporal behavior of the phase difference across the tu...

  4. Improved visualization of breast cancer features in multifocal carcinoma using phase-contrast and dark-field mammography: an ex vivo study

    Energy Technology Data Exchange (ETDEWEB)

    Grandl, Susanne; Sztrokay-Gaul, Aniko; Auweter, Sigrid D.; Hellerhoff, Karin [Ludwig-Maximilians-University Hospital Munich, Institute of Clinical Radiology, Munich (Germany); Scherer, Kai; Birnbacher, Lorenz; Willer, Konstantin; Chabior, Michael; Herzen, Julia; Pfeiffer, Franz [Technische Universitaet Muenchen, Department of Physics and Institute of Medical Engineering, Garching (Germany); Mayr, Doris [Ludwig-Maximilians-Universitaet Muenchen, Institute of Pathology, Munich (Germany); Bamberg, Fabian [University Hospital Tuebingen, Department of Diagnostic and Interventional Radiology, Tuebingen (Germany)

    2015-12-15

    Conventional X-ray attenuation-based contrast is inherently low for the soft-tissue components of the female breast. To overcome this limitation, we investigate the diagnostic merits arising from dark-field mammography by means of certain tumour structures enclosed within freshly dissected mastectomy samples. We performed grating-based absorption, absolute phase and dark-field mammography of three freshly dissected mastectomy samples containing bi- and multifocal carcinoma using a compact, laboratory Talbot-Lau interferometer. Preoperative in vivo imaging (digital mammography, ultrasound, MRI), postoperative histopathological analysis and ex vivo digital mammograms of all samples were acquired for the diagnostic verification of our results. In the diagnosis of multifocal tumour growth, dark-field mammography seems superior to standard breast imaging modalities, providing a better resolution of small, calcified tumour nodules, demarcation of tumour boundaries with desmoplastic stromal response and spiculated soft-tissue strands extending from an invasive ductal breast cancer. On the basis of selected cases, we demonstrate that dark-field mammography is capable of outperforming conventional mammographic imaging of tumour features in both calcified and non-calcified tumours. Presuming dose optimization, our results encourage further studies on larger patient cohorts to identify those patients that will benefit the most from this promising additional imaging modality. (orig.)

  5. Improved visualization of breast cancer features in multifocal carcinoma using phase-contrast and dark-field mammography: an ex vivo study

    International Nuclear Information System (INIS)

    Conventional X-ray attenuation-based contrast is inherently low for the soft-tissue components of the female breast. To overcome this limitation, we investigate the diagnostic merits arising from dark-field mammography by means of certain tumour structures enclosed within freshly dissected mastectomy samples. We performed grating-based absorption, absolute phase and dark-field mammography of three freshly dissected mastectomy samples containing bi- and multifocal carcinoma using a compact, laboratory Talbot-Lau interferometer. Preoperative in vivo imaging (digital mammography, ultrasound, MRI), postoperative histopathological analysis and ex vivo digital mammograms of all samples were acquired for the diagnostic verification of our results. In the diagnosis of multifocal tumour growth, dark-field mammography seems superior to standard breast imaging modalities, providing a better resolution of small, calcified tumour nodules, demarcation of tumour boundaries with desmoplastic stromal response and spiculated soft-tissue strands extending from an invasive ductal breast cancer. On the basis of selected cases, we demonstrate that dark-field mammography is capable of outperforming conventional mammographic imaging of tumour features in both calcified and non-calcified tumours. Presuming dose optimization, our results encourage further studies on larger patient cohorts to identify those patients that will benefit the most from this promising additional imaging modality. (orig.)

  6. Quantitative strain mapping of InAs/InP quantum dots with 1 nm spatial resolution using dark field electron holography

    DEFF Research Database (Denmark)

    Cooper, David; Rouviere, Jean-Luc; Béché, Armand;

    2011-01-01

    The optical properties of semiconductor quantum dots are greatly influenced by their strain state. Dark field electron holography has been used to measure the strain in InAs quantum dots grown in InP with a spatial resolution of 1 nm. A strain value of 5.4%60.1% has been determined which is consi...

  7. 扫描透射电子显微镜及电子能量损失谱的原理及应用%The principle and applications of STEM and EELS

    Institute of Scientific and Technical Information of China (English)

    李超; 杨光

    2014-01-01

    扫描透射电子显微镜是透射电子显微镜的一种,近几年随着球差校正器的问世,扫描透射电子显微镜的分辨率达到亚埃级,结合能量分辨率为亚电子伏特的电子能量损失谱,可以对材料进行高空间分辨率及高能量分辨率的微结构和成分分析。文章简述了扫描透射电子显微镜的发展历程和工作原理,重点讲述了高角环形暗场像的成像机理以及基于高角环形暗场像对材料结构和成分进行分析的原理和应用;电子能量损失谱的成谱过程、谱的特征及其在材料化学和电子结构分析方面的优势和主要应用。%The scanning transmission electron microscope (STEM) is one kind of trans-mission electron microscope. With the invention of the spherical aberration corrector, the resolu-tion of STEM can reach sub-Ångstrom levels. High spatial resolution imaging and high energy resolution spectroscopy can be achieved simultaneously through the combination of STEM and electron energy loss spectroscopy (EELS). The fundamentals and application of STEM will be briefly introduced, with emphasis on the basics of high angle annular dark field imaging and its application in microstructural and chemical analyses. The characteristic features of EELS and its application in material science will also be discussed.

  8. Optical Dark-Field and Electron Energy Loss Imaging and Spectroscopy of Symmetry-Forbidden Modes in Loaded Nanogap Antennas.

    Science.gov (United States)

    Brintlinger, Todd; Herzing, Andrew A; Long, James P; Vurgaftman, Igor; Stroud, Rhonda; Simpkins, B S

    2015-06-23

    We have produced large numbers of hybrid metal-semiconductor nanogap antennas using a scalable electrochemical approach and systematically characterized the spectral and spatial character of their plasmonic modes with optical dark-field scattering, electron energy loss spectroscopy with principal component analysis, and full wave simulations. The coordination of these techniques reveal that these nanostructures support degenerate transverse modes which split due to substrate interactions, a longitudinal mode which scales with antenna length, and a symmetry-forbidden gap-localized transverse mode. This gap-localized transverse mode arises from mode splitting of transverse resonances supported on both antenna arms and is confined to the gap load enabling (i) delivery of substantial energy to the gap material and (ii) the possibility of tuning the antenna resonance via active modulation of the gap material's optical properties. The resonant position of this symmetry-forbidden mode is sensitive to gap size, dielectric strength of the gap material, and is highly suppressed in air-gapped structures which may explain its absence from the literature to date. Understanding the complex modal structure supported on hybrid nanosystems is necessary to enable the multifunctional components many seek.

  9. Improved In vivo Assessment of Pulmonary Fibrosis in Mice using X-Ray Dark-Field Radiography

    Science.gov (United States)

    Yaroshenko, Andre; Hellbach, Katharina; Yildirim, Ali Önder; Conlon, Thomas M.; Fernandez, Isis Enlil; Bech, Martin; Velroyen, Astrid; Meinel, Felix G.; Auweter, Sigrid; Reiser, Maximilian; Eickelberg, Oliver; Pfeiffer, Franz

    2015-12-01

    Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease with a median life expectancy of 4-5 years after initial diagnosis. Early diagnosis and accurate monitoring of IPF are limited by a lack of sensitive imaging techniques that are able to visualize early fibrotic changes at the epithelial-mesenchymal interface. Here, we report a new x-ray imaging approach that directly visualizes the air-tissue interfaces in mice in vivo. This imaging method is based on the detection of small-angle x-ray scattering that occurs at the air-tissue interfaces in the lung. Small-angle scattering is detected with a Talbot-Lau interferometer, which provides the so-called x-ray dark-field signal. Using this imaging modality, we demonstrate-for the first time-the quantification of early pathogenic changes and their correlation with histological changes, as assessed by stereological morphometry. The presented radiography method is significantly more sensitive in detecting morphological changes compared with conventional x-ray imaging, and exhibits a significantly lower radiation dose than conventional x-ray CT. As a result of the improved imaging sensitivity, this new imaging modality could be used in future to reduce the number of animals required for pulmonary research studies.

  10. Non newtonian annular alloy solidification in mould

    Energy Technology Data Exchange (ETDEWEB)

    Moraga, Nelson O.; Garrido, Carlos P. [Universidad de La Serena, Departamento de Ingenieria Mecanica, La Serena (Chile); Castillo, Ernesto F. [Universidad de Santiago de Chile, Departamento de Ingenieria Mecanica, Santiago (Chile)

    2012-08-15

    The annular solidification of an aluminium-silicon alloy in a graphite mould with a geometry consisting of horizontal concentric cylinders is studied numerically. The analysis incorporates the behavior of non-Newtonian, pseudoplastic (n=0.2), Newtonian (n=1), and dilatant (n=1.5) fluids. The fluid mechanics and heat transfer coupled with a transient model of convection diffusion are solved using the finite volume method and the SIMPLE algorithm. Solidification is described in terms of a liquid fraction of a phase change that varies linearly with temperature. The final results make it possible to infer that the fluid dynamics and heat transfer of solidification in an annular geometry are affected by the non-Newtonian nature of the fluid, speeding up the process when the fluid is pseudoplastic. (orig.)

  11. Annular pancreas associated with duodenal carcinoma

    Institute of Scientific and Technical Information of China (English)

    Enrico; Bronnimann; Silke; Potthast; Tatjana; Vlajnic; Daniel; Oertli; Oleg; Heizmann

    2010-01-01

    Annular pancreas (AP) is a rare congenital anomaly. Coexisting malignancy has been reported only in a few cases. We report what is, to the best of our knowledge, the first case in the English literature of duodenal adenocarcinoma in a patient with AP. In a 55-year old woman with duodenal outlet stenosis magnetic resonance cholangiopancreatography showed an aberrant pancreatic duct encircling the duodenum. Duodenojejunostomy was performed. Eight weeks later she presented with painless jaundice. Duodenopancre...

  12. Performance of annular high frequency thermoacoustic engines

    Science.gov (United States)

    Rodriguez, Ivan A.

    This thesis presents studies of the behavior of miniature annular thermoacoustic prime movers and the imaging of the complex sound fields using PIV inside the small acoustic wave guides when driven by a temperature gradient. Thermoacoustic engines operating in the standing wave mode are limited in their acoustic efficiency by a high degree of irreversibility that is inherent in how they work. Better performance can be achieved by using traveling waves in the thermoacoustic devices. This has led to the development of an annular high frequency thermoacoustic prime mover consisting of a regenerator, which is a random stack in-between a hot and cold heat exchanger, inside an annular waveguide. Miniature devices were developed and studied with operating frequencies in the range of 2-4 kHz. This corresponds to an average ring circumference of 11 cm for the 3 kHz device, the resonator bore being 6 mm. A similar device of 11 mm bore, length of 18 cm was also investigated; its resonant frequency was 2 kHz. Sound intensities as high as 166.8 dB were generated with limited heat input. Sound power was extracted from the annular structure by an impedance-matching side arm. The nature of the acoustic wave generated by heat was investigated using a high speed PIV instrument. Although the acoustic device appears symmetric, its performance is characterized by a broken symmetry and by perturbations that exist in its structure. Effects of these are observed in the PIV imaging; images show axial and radial components. Moreover, PIV studies show effects of streaming and instabilities which affect the devices' acoustic efficiency. The acoustic efficiency is high, being of 40% of Carnot. This type of device shows much promise as a high efficiency energy converter; it can be reduced in size for microcircuit applications.

  13. Annular Alopecia Areata: Report of Two Cases

    OpenAIRE

    Bansal, Manish; Manchanda, Kajal; Pandey, SS

    2013-01-01

    Alopecia areata (AA) is an auto-immune disorder characterized by the appearance of non-scarring bald patches affecting the hair bearing areas of the body. Scalp is the most common site of involvement. AA can affect any age group. The usual pattern of the hair loss is oval or round. We hereby, report two cases of annular and circinate pattern of AA due to its unusual morphology.

  14. Diagnosing and mapping pulmonary emphysema on X-ray projection images: incremental value of grating-based X-ray dark-field imaging.

    Directory of Open Access Journals (Sweden)

    Felix G Meinel

    Full Text Available PURPOSE: To assess whether grating-based X-ray dark-field imaging can increase the sensitivity of X-ray projection images in the diagnosis of pulmonary emphysema and allow for a more accurate assessment of emphysema distribution. MATERIALS AND METHODS: Lungs from three mice with pulmonary emphysema and three healthy mice were imaged ex vivo using a laser-driven compact synchrotron X-ray source. Median signal intensities of transmission (T, dark-field (V and a combined parameter (normalized scatter were compared between emphysema and control group. To determine the diagnostic value of each parameter in differentiating between healthy and emphysematous lung tissue, a receiver-operating-characteristic (ROC curve analysis was performed both on a per-pixel and a per-individual basis. Parametric maps of emphysema distribution were generated using transmission, dark-field and normalized scatter signal and correlated with histopathology. RESULTS: Transmission values relative to water were higher for emphysematous lungs than for control lungs (1.11 vs. 1.06, p<0.001. There was no difference in median dark-field signal intensities between both groups (0.66 vs. 0.66. Median normalized scatter was significantly lower in the emphysematous lungs compared to controls (4.9 vs. 10.8, p<0.001, and was the best parameter for differentiation of healthy vs. emphysematous lung tissue. In a per-pixel analysis, the area under the ROC curve (AUC for the normalized scatter value was significantly higher than for transmission (0.86 vs. 0.78, p<0.001 and dark-field value (0.86 vs. 0.52, p<0.001 alone. Normalized scatter showed very high sensitivity for a wide range of specificity values (94% sensitivity at 75% specificity. Using the normalized scatter signal to display the regional distribution of emphysema provides color-coded parametric maps, which show the best correlation with histopathology. CONCLUSION: In a murine model, the complementary information provided by X

  15. Vibration analysis of annular-like plates

    Science.gov (United States)

    Cheng, L.; Li, Y. Y.; Yam, L. H.

    2003-05-01

    The existence of eccentricity of the central hole for an annular plate results in a significant change in the natural frequencies and mode shapes of the structure. In this paper, the vibration analysis of annular-like plates is presented based on numerical and experimental approaches. Using the finite element analysis code Nastran, the effects of the eccentricity, hole size and boundary condition on vibration modes are investigated systematically through both global and local analyses. The results show that analyses for perfect symmetric conditions can still roughly predict the mode shapes of "recessive" modes of the plate with a slightly eccentric hole. They will, however, lead to erroneous results for "dominant" modes. In addition, the residual displacement mode shape is verified as an effective parameter for identifying damage occurring in plate-like structures. Experimental modal analysis on a clamped-free annular-like plate is performed, and the results obtained reveal good agreement with those obtained by numerical analysis. This study provides guidance on modal analysis, vibration measurement and damage detection of plate-like structures.

  16. Nanoscale strain distributions in embedded SiGe semiconductor devices revealed by precession electron diffraction and dual lens dark field electron holography

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Y. Y. [IBM Micro-Electronics Division, 2070 Route 52, Hopewell Junction, New York 12570 (United States); Cooper, D.; Bernier, N. [University Grenoble Alpes, F-38000 Grenoble (France); CEA, LETI, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Rouviere, J. [University Grenoble Alpes, F-38000 Grenoble (France); CEA, INAC, MINATEC Campus, 17 rue des Martyrs, 38054 Grenoble Cedex 9 (France); Murray, C. E.; Bruley, J. [IBM T. J. Watson Research Center, 1101 Kitchawan Road, Route 134, Yorktown Heights, New York 10598 (United States)

    2015-01-26

    The detailed strain distributions produced by embedded SiGe stressor structures are measured at high spatial resolution with high precision, with dual lens dark field electron holography and precession electron diffraction. Shear strain and lattice rotation within the crystalline lattice are observed at the boundaries between the SiGe and Si regions. The experimental results are compared to micromechanical modeling simulations to understand the mechanisms of elastic relaxation on all the modes of deformation at a sub-micron length scale.

  17. Effect of Annular Slit Geometry on Characteristics of Spiral Jet

    Institute of Scientific and Technical Information of China (English)

    Shigeru Matsuo; Kwon-Hee Lee; Shinsuke Oda; Toshiaki Setoguchi; Heuy-Dong Kim

    2003-01-01

    A spiral flow using an annular slit connected to a conical cylinder does not need special device to generate a tangential velocity component of the flow and differs from swirling flows. Pressurized fluid is supplied to an annular chamber and injected into the convergent nozzle through the annular slit. The annular jet develops into the spiral flow. In the present study, a spiral jet discharged out of nozzle exit was obtained by using a convergent nozzle and an annular slit set in nozzle inlet, and the effect of annular slit geometry on characteristics of the spiral jet was investigated by using a Laser Doppler Velocimeter (LDV) experimentally. Furthermore, velocity distributions of the spiral jet were compared with those of a normal jet.

  18. Granuloma annulare localized to the shaft of the penis

    DEFF Research Database (Denmark)

    Trap, R; Wiebe, B

    1993-01-01

    A case of granuloma annulare localized to the shaft of the penis is reported. The differential diagnoses are discussed. Penile granuloma annulare is a rare disorder and it is concluded that biopsies of penile lesions are recommended to verify the correct diagnosis.......A case of granuloma annulare localized to the shaft of the penis is reported. The differential diagnoses are discussed. Penile granuloma annulare is a rare disorder and it is concluded that biopsies of penile lesions are recommended to verify the correct diagnosis....

  19. Quantitative analysis of interfacial strain in InAs/GaSb superlattices by aberration-corrected HRTEM and HAADF-STEM.

    Science.gov (United States)

    Mahalingam, Krishnamurthy; Haugan, Heather J; Brown, Gail J; Eyink, Kurt G

    2013-04-01

    The strain distribution across interfaces in InAs/GaSb superlattices grown on (100)-GaSb substrates is investigated by aberration corrected transmission electron microscopy. Atomic resolution images of interfaces were obtained by conventional high resolution transmission electron microscopy (HRTEM), using the negative spherical-aberration imaging mode, and by scanning transmission electron microscopy (STEM), using the high-angle annular dark-field (HAADF) imaging mode. The local atomic displacements across interfaces were determined from these images using the peak pair algorithm, from which strain maps were calculated with respect to a reference lattice extracted from the GaSb substrate region. Both techniques yield consistent results, which reveal that the InAs-on-GaSb interface is nearly strain balanced, whereas the GaSb-on-InAs interface is in tensile strain, indicating that the prevalent bond type at this interface is Ga-As. In addition, the GaSb layers in the superlattice are compressively strained indicating the incorporation of In into these layers. Further analysis of the HAADF-STEM images indicates an estimated 4% In content in the GaSb layers and that the GaSb-on-InAs interface contributes to about 27% of the overall superlattice strain. The strain measurements in the InAs layers are in good agreement with the theoretical values determined from elastic constants. Furthermore, the overall superlattice strain determined from this analysis is also in good agreement with the measurements determined by high-resolution X-ray diffraction.

  20. Wave turbulence in annular wave tank

    Science.gov (United States)

    Onorato, Miguel; Stramignoni, Ettore

    2014-05-01

    We perform experiments in an annular wind wave tank at the Dipartimento di Fisica, Universita' di Torino. The external diameter of the tank is 5 meters while the internal one is 1 meter. The tank is equipped by two air fans which can lead to a wind of maximum 5 m/s. The present set up is capable of studying the generation of waves and the development of wind wave spectra for large duration. We have performed different tests including different wind speeds. For large wind speed we observe the formation of spectra consistent with Kolmogorv-Zakharov predictions.

  1. Finite stretching of an annular plate.

    Science.gov (United States)

    Biricikoglu, V.; Kalnins, A.

    1971-01-01

    The problem of the finite stretching of an annular plate which is bonded to a rigid inclusion at its inner edge is considered. The material is assumed to be isotropic and incompressible with a Mooney-type constitutive law. It is shown that the inclusion of the effect of the transverse normal strain leads to a rapid variation in thickness which is confined to a narrow edge zone. The explicit solutions to the boundary layer equations, which govern the behavior of the plate near the edges, are presented.

  2. Thread-annular flow in vertical pipes

    Science.gov (United States)

    Frei, Ch.; Lüscher, P.; Wintermantel, E.

    2000-05-01

    Thread injection is a promising method for different minimally invasive medical applications. This paper documents an experimental study dealing with an axially moving thread in annular pipe flow. Mass flow and axial force on the thread are measured for a 0.46 mm diameter thread in pipes with diameters between 0.55 and 1.35 mm. The experiments with thread velocities of up to 1.5 ms[minus sign]1 confirm the findings of theoretical studies that for clinical requirements the radius ratio between thread and pipe is crucial for the adjustments of mass ow and force on the thread.

  3. Deep variant of Erythema Annulare Centrifugum

    OpenAIRE

    Ahu Yorulmaz; Ferda Artuz; Devrim Tuba Unal

    2014-01-01

    A 29-year-old woman came to our outpatient clinic with a several-month history of itchy red lesions over her trunk. There was no family history and past history of any other diseases or medication. Dermatological examination revealed annular and oval-shaped plaques up to several cm’s in size, one of which was polycyclic in configuration, on back of the patient (Fig. 1). It was also noticed that lesions had erythematous indurated bordes with paler central areas (Fig. 1).

  4. Deep variant of Erythema Annulare Centrifugum

    Directory of Open Access Journals (Sweden)

    Ahu Yorulmaz

    2014-10-01

    Full Text Available A 29-year-old woman came to our outpatient clinic with a several-month history of itchy red lesions over her trunk. There was no family history and past history of any other diseases or medication. Dermatological examination revealed annular and oval-shaped plaques up to several cm’s in size, one of which was polycyclic in configuration, on back of the patient (Fig. 1. It was also noticed that lesions had erythematous indurated bordes with paler central areas (Fig. 1.

  5. Annular lupus vulgaris mimicking tinea cruris.

    Science.gov (United States)

    Heo, Young Soo; Shin, Won Woong; Kim, Yong Ju; Song, Hae Jun; Oh, Chil Hwan

    2010-05-01

    Cutaneous tuberculosis is an infrequent form of extrapulmonary tuberculosis. It is often clinically and histopathologically confused with various cutaneous disorders. A 36-year-old man attended our clinic with slowly progressive, asymptomatic, annular skin lesions on both the thighs and buttocks for 10 years. He consulted with many physicians and was improperly treated with an oral antifungal agent for several months under the diagnosis of tinea cruris, but no resolution of his condition was observed. A diagnosis of lupus vulgaris was made based on the histopathologic examination and the polymerase chain reaction assay. Anti-tuberculosis therapy was administered and the lesions started to regress.

  6. Mass transport in annular spherical system

    Science.gov (United States)

    Bauer, Helmut F.

    The mass transport between two concentric spheres with inlet and outlet at the poles was determined for ideal liquid flow (plug flow) and laminar flow for constant concentration at the spherical walls and constant concentration at the inlet. Velocity distribution and local concentration profiles were determined analytically for various widths of the annular spherical conduit and various diffusive flow parameters. It is found that with the increase of this parameter, the decay becomes quite rapid and that the same effect occurs for increasing diameter ratio of the spheres. This configuration may possibly be used as a basic element of an artificial kidney.

  7. Annular and semicircular lipoatrophies. Report of three cases and review of the literature.

    Science.gov (United States)

    Rongioletti, F; Rebora, A

    1989-03-01

    Two cases of semicircular lipoatrophy and one of annular lipoatrophy are presented. The reasons why semicircular lipoatrophy, annular lipoatrophy, and annular atrophy of the ankles seem to be different clinical entities are discussed.

  8. Detonation diffraction from an annular channel

    Science.gov (United States)

    Meredith, James; Ng, Hoi Dick; Lee, John H. S.

    2010-12-01

    In this study, gaseous detonation diffraction from an annular channel was investigated with a streak camera and the critical pressure for transmission of the detonation wave was obtained. The annular channel was used to approximate an infinite slot resulting in cylindrically expanding detonation waves. Two mixtures, stoichiometric acetylene-oxygen and stoichiometric acetylene-oxygen with 70% Ar dilution, were tested in a 4.3 and 14.3 mm channel width ( W). The undiluted and diluted mixtures were found to have values of the critical channel width over the cell size around 3 and 12 respectively. Comparing these results to values of the critical diameter ( d c ), in which a spherical detonation occurs, a value of critical d c / W c near 2 is observed for the highly diluted mixture. This value corresponds to the geometrical factor of the curvature term between a spherical and cylindrical diverging wave. Hence, the result is in support of Lee's proposed mechanism [Lee in Dynamics of Exothermicity, pp. 321, Gordon and Breach, Amsterdam, 1996] for failure due to diffraction based on curvature in stable mixtures such as those highly argon diluted with very regular detonation cellular patterns.

  9. Annular beam shaping and optical trepanning

    Science.gov (United States)

    Zeng, Danyong

    Percussion drilling and trepanning are two laser drilling methods. Percussion drilling is accomplished by focusing the laser beam to approximately the required diameter of the hole, exposing the material to one or a series of laser pulses at the same spot to melt and vaporize the material. Drilling by trepanning involves cutting a hole by rotating a laser beam with an optical element or an x-y galvo-scanner. Optical trepanning is a new laser drilling method using an annular beam. The annular beams allow numerous irradiance profiles to supply laser energy to the workpiece and thus provide more flexibility in affecting the hole quality than a traditional circular laser beam. Heating depth is important for drilling application. Since there are no good ways to measure the temperature inside substrate during the drilling process, an analytical model for optical trepanning has been developed by considering an axisymmetric, transient heat conduction equation, and the evolutions of the melting temperature isotherm, which is referred to as the melt boundary in this study, are calculated to investigate the influences of the laser pulse shapes and intensity profiles on the hole geometry. This mathematical model provides a means of understanding the thermal effect of laser irradiation with different annular beam shapes. To take account of conduction in the solid, vaporization and convection due to the melt flow caused by an assist gas, an analytical two-dimensional model is developed for optical trepanning. The influences of pulse duration, laser pulse length, pulse repetition rate, intensity profiles and beam radius are investigated to examine their effects on the recast layer thickness, hole depth and taper. The ray tracing technique of geometrical optics is employed to design the necessary optics to transform a Gaussian laser beam into an annular beam of different intensity profiles. Such profiles include half Gaussian with maximum intensities at the inner and outer

  10. Limited Diffraction Maps for Pulsed Wave Annular Arrays

    DEFF Research Database (Denmark)

    Fox, Paul D.

    2002-01-01

    A procedure is provided for decomposing the linear field of flat pulsed wave annular arrays into an equivalent set of known limited diffraction Bessel beams. Each Bessel beam propagates with known characteristics, enabling good insight into the propagation of annular fields to be obtained...

  11. Obtention of an empirical equation for annular channels

    International Nuclear Information System (INIS)

    Using a trial circuit, the experimental heat transfer coefficient is determined, in forced convection at one phase only within an annular channel in which water flows ascendantly and for this reason an empirical equation is determined. This work tries to contribute to the understanding of the forced convection phenomena in non tubular geometries like the annular channels. (Author)

  12. 75 FR 23582 - Annular Casing Pressure Management for Offshore Wells

    Science.gov (United States)

    2010-05-04

    ... Recommended Practice (RP) 90. As explained in API RP 90, Section 3, Annular Casing Pressure Management Program... Institute's Recommended Practice for managing annular casing pressure. New regulations are needed because... Continental Shelf lessees to follow best industry practices for wells with sustained casing pressure....

  13. Effect of annular secondary conductor in a linear electromagnetic stirrer

    Indian Academy of Sciences (India)

    R Madhavan; V Ramanarayanan

    2008-10-01

    This paper presents the variation of average axial force density in the annular secondary conductor of a linear electromagnetic stirrer. Different geometries of secondaries are considered for numerical and experimental validation namely, 1. hollow annular ring, 2. annular ring with a solid cylinder and 3. solid cylinder. Experimental and numerical simulations are performed for a 2-pole in house built 15 kW linear electromagnetic stirrer (EMS). It is observed for a supply current of 200 A at 30 Hz the force densities in the hollow annular ring is 67% higher than the equivalent solid cylinder. The same values are 33% for annular ring with a solid cylinder. Force density variation with supply frequency and current are also reported. Numerical simulations using finite element model are validated with experimental results.

  14. Dual-Band Annular-Ring Microstrip Patch Antenna for Satellite Applications

    Directory of Open Access Journals (Sweden)

    Tvs Divakar

    2014-08-01

    Full Text Available A dual-band circularly polarized antenna fed by four apertures that covers the bands of GPS, Galileo, is introduced. The ARSAs designed using FR4 substrates in the L and S bands have 3-dB axial-ratio bandwidths (ARBWs of as large as 37% and 52%, respectively, whereas the one using an RT5880 substrate in the L band, 61%. In these 3-dB axial-ratio bands, impedance matching with VSWR<=1.8 is also achieved. Three wideband planar baluns are used to achieve good axial ratio and VSWR. The results of the annular-ring microstrip antenna show good performance of a dual-band operation, which meets the requirement of Global Navigation Satellite System (GNSS applications.

  15. Beam tracking approach for single–shot retrieval of absorption, refraction, and dark-field signals with laboratory  x-ray sources

    International Nuclear Information System (INIS)

    We present the translation of the beam tracking approach for x-ray phase-contrast and dark-field imaging, recently demonstrated using synchrotron radiation, to a laboratory setup. A single absorbing mask is used before the sample, and a local Gaussian interpolation of the beam at the detector is used to extract absorption, refraction, and dark–field signals from a single exposure of the sample. Multiple exposures can be acquired when high resolution is needed, as shown here. A theoretical analysis of the effect of polychromaticity on the retrieved signals, and of the artifacts this might cause when existing retrieval methods are used, is also discussed

  16. Beam tracking approach for single–shot retrieval of absorption, refraction, and dark-field signals with laboratory  x-ray sources

    Energy Technology Data Exchange (ETDEWEB)

    Vittoria, Fabio A., E-mail: fabio.vittoria.12@ucl.ac.uk; Diemoz, Paul C.; Olivo, Alessandro [Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, London WC1E 6BT (United Kingdom); Research Complex at Harwell, Harwell Oxford Campus, OX11 0FA Didcot (United Kingdom); Kallon, Gibril K. N.; Basta, Dario; Endrizzi, Marco [Department of Medical Physics and Biomedical Engineering, University College London, Malet Place, Gower Street, London WC1E 6BT (United Kingdom); Robinson, Ian K. [Research Complex at Harwell, Harwell Oxford Campus, OX11 0FA Didcot (United Kingdom); London Centre for Nanotechnology, WC1H 0AH London (United Kingdom)

    2015-06-01

    We present the translation of the beam tracking approach for x-ray phase-contrast and dark-field imaging, recently demonstrated using synchrotron radiation, to a laboratory setup. A single absorbing mask is used before the sample, and a local Gaussian interpolation of the beam at the detector is used to extract absorption, refraction, and dark–field signals from a single exposure of the sample. Multiple exposures can be acquired when high resolution is needed, as shown here. A theoretical analysis of the effect of polychromaticity on the retrieved signals, and of the artifacts this might cause when existing retrieval methods are used, is also discussed.

  17. Macroscopic benchmark testing notes in light- dark field transformation%明暗场转换环境下的宏观检验注意事项

    Institute of Scientific and Technical Information of China (English)

    李波

    2011-01-01

    As a result of the existing light adaptation and dark adaptation phenomenon of the human eyes in light - dark field transforma- tion, it causes the macroscopic undetected defects. This thesis puts forward the solution to solve such problem.%由于人眼在明暗场转换环境下存在光适应和暗适应现象,造成宏观检验检不出缺陷.提出针对该现象的解决方法。

  18. The role of side stream dark field microvasculature imaging in a rare case of vancomycin-resistant enterococcal endocarditis complicated by heparin-induced thrombocytopenia

    Directory of Open Access Journals (Sweden)

    Janak Bechar

    2016-01-01

    Full Text Available Sidestream dark field (SDF imaging allows direct visualization of microvascular architecture and function. We examine the role of an SDF imaging device in visualizing the sub-lingual microvasculature as a surrogate for splanchnic microperfusion. We demonstrate good correlation between current monitoring techniques and the SDF imaging device in a rare case of vancomycin-resistant enterococcal (VRE sepsis along with heparin-induced thrombocytopenia (HIT. To the best of our knowledge, VRE endocarditis with concurrent HIT has not been described in literature. The role of SDF imaging may predict the earlier need for escalation of care, improving morbidity and mortality.

  19. Facility modernization Annular Core Research Reactor

    International Nuclear Information System (INIS)

    The Annular Core Research Reactor (ACRR) has undergone numerous modifications since its conception in response to program needs. The original reactor fuel, which was special U-ZrH TRIGA fuel designed primarily for pulsing, has been replaced with a higher pulsing capacity BeO fuel. Other advanced operating modes which use this increased capability, in addition to the pulse and steady state, have been incorporated to tailor power histories and fluences to the experiments. Various experimental facilities have been developed that range from a radiography facility to a 50 cm diameter External Fuel Ring Cavity (FREC) using 180 of the original ZrH fuel elements. Currently a digital reactor console is being produced with GA, which will give enhanced monitoring capabilities of the reactor parameters while leaving the safety-related shutdown functions with analog technology. (author)

  20. Annular MHD Physics for Turbojet Energy Bypass

    Science.gov (United States)

    Schneider, Steven J.

    2011-01-01

    The use of annular Hall type MHD generator/accelerator ducts for turbojet energy bypass is evaluated assuming weakly ionized flows obtained from pulsed nanosecond discharges. The equations for a 1-D, axisymmetric MHD generator/accelerator are derived and numerically integrated to determine the generator/accelerator performance characteristics. The concept offers a shockless means of interacting with high speed inlet flows and potentially offers variable inlet geometry performance without the complexity of moving parts simply by varying the generator loading parameter. The cycle analysis conducted iteratively with a spike inlet and turbojet flying at M = 7 at 30 km altitude is estimated to have a positive thrust per unit mass flow of 185 N-s/kg. The turbojet allowable combustor temperature is set at an aggressive 2200 deg K. The annular MHD Hall generator/accelerator is L = 3 m in length with a B(sub r) = 5 Tesla magnetic field and a conductivity of sigma = 5 mho/m for the generator and sigma= 1.0 mho/m for the accelerator. The calculated isentropic efficiency for the generator is eta(sub sg) = 84 percent at an enthalpy extraction ratio, eta(sub Ng) = 0.63. The calculated isentropic efficiency for the accelerator is eta(sub sa) = 81 percent at an enthalpy addition ratio, eta(sub Na) = 0.62. An assessment of the ionization fraction necessary to achieve a conductivity of sigma = 1.0 mho/m is n(sub e)/n = 1.90 X 10(exp -6), and for sigma = 5.0 mho/m is n(sub e)/n = 9.52 X 10(exp -6).

  1. Recurrent Annular Peripheral Choroidal Detachment after Trabeculectomy

    Directory of Open Access Journals (Sweden)

    Shaohui Liu

    2013-10-01

    Full Text Available We report a challenging case of recurrent flat anterior chamber without hypotony after trabeculectomy in a 54-year-old Black male with a remote history of steroid-treated polymyositis, cataract surgery, and uncontrolled open angle glaucoma. The patient presented with a flat chamber on postoperative day 11, but had a normal fundus exam and intraocular pressure (IOP. Flat chamber persisted despite treatment with cycloplegics, steroids, and a Healon injection into the anterior chamber. A transverse B-scan of the peripheral fundus revealed a shallow annular peripheral choroidal detachment. The suprachoroidal fluid was drained. The patient presented 3 days later with a recurrent flat chamber and an annular peripheral choroidal effusion. The fluid was removed and reinforcement of the scleral flap was performed with the resolution of the flat anterior chamber. A large corneal epithelial defect developed after the second drainage. The oral prednisone was tapered quickly and the topical steroid was decreased. One week later, his vision decreased to count fingers with severe corneal stromal edema and Descemet's membrane folds that improved to 20/50 within 24 h of resumption of the oral steroid and frequent topical steroid. The patient's visual acuity improved to 20/20 following a slow withdrawal of the oral and topical steroid. Eight months after surgery, the IOP was 15 mm Hg without glaucoma medication. The detection of a shallow anterior choroidal detachment by transverse B-scan is critical to making the correct diagnosis. Severe cornea edema can occur if the steroid is withdrawn too quickly. Thus, steroids should be tapered cautiously in steroid-dependent patients.

  2. Characteristics of Electromagnetic Pulse Coupling into Annular Apertures

    Directory of Open Access Journals (Sweden)

    Yan-Peng Sun

    2013-11-01

    Full Text Available Electromagnetic pulse (EMP coupling into the annular apertures can disturb or damage much electronic equipment. To enhance electronic system’s  capability of anti-electromagnetic interference, the finite difference time domain method (FDTD was employed to study the characteristics of electromagnetic pulse coupling into the cavity enclosures with annular apertures. The coupling characteristics of annular apertures with different shapes (rectangle, square and circle were discussed. It shows that, in the case of the same aperture area, the coupling energy of electromagnetic pulse into the circular annular aperture is smaller than that into the rectangular and the square ones. To the rectangular annular aperture, while the polarization direction of the incident electromagnetic pulse is perpendicular to the long side of the rectangular annular aperture, the coupling energy is larger when the aspect ratio of the rectangular annular aperture is larger. The coupling effect of incident pulse with short pulse width is obviously better than the one with longer pulse width. The resonance phenomenon of the coupled waveform occurs in the cavity.

  3. Detonation Initiation by Annular Jets and Shock Waves

    OpenAIRE

    Shepherd, Joseph E.

    2005-01-01

    The objective of this research is to experimentally determine the feasibility of initiating detonation in fuel-air mixtures using only the energy in hot, compressed air. The existing 6-inch shock tube at Caltech was used to create hot, high-pressure air behind a reflected shock wave. The hot air created an imploding annular shock wave when it jetted through an annular orifice into a 76-mm-diameter, 1-m-long tube attached to the end of the shock tube. A special test section with an annular ...

  4. Radiation and reflection acoustical fields of an annular phased array

    Institute of Scientific and Technical Information of China (English)

    LAI Puxiang; ZHANG Bixing; WANG Chenghao

    2007-01-01

    The characteristics of the radiation and reflection acoustical fields of an annular phased array are investigated. The effects of the element number, element radius, interelement spacing, centre frequency, focus position, and other parameters on the radiation acoustical field of the annular phased array is theoretically studied. In experiment, an annular transducer with 8 equal-area elements is designed and fabricated, and a series of experimental measurements are conducted. The radiation acoustical field and its reflection on a liquid-solid interface are theoretically and experimentally studied. The experimental result is in good agreement with the theoretical one.

  5. Principle of radial transport in low temperature annular plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yunchao, E-mail: yunchao.zhang@anu.edu.au; Charles, Christine; Boswell, Rod [Space Plasma, Power and Propulsion Laboratory, Research School of Physics and Engineering, The Australian National University, Bldg 60, Mills Road, Australian Capital Territory 2601 (Australia)

    2015-07-15

    Radial transport in low temperature annular plasmas is investigated theoretically in this paper. The electrons are assumed to be in quasi-equilibrium due to their high temperature and light inertial mass. The ions are not in equilibrium and their transport is analyzed in three different situations: a low electric field (LEF) model, an intermediate electric field (IEF) model, and a high electric field (HEF) model. The universal IEF model smoothly connects the LEF and HEF models at their respective electric field strength limits and gives more accurate results of the ion mobility coefficient and effective ion temperature over the entire electric field strength range. Annular modelling is applied to an argon plasma and numerical results of the density peak position, the annular boundary loss coefficient and the electron temperature are given as functions of the annular geometry ratio and Paschen number.

  6. New mitral annular force transducer optimized to distinguish annular segments and multi-plane forces.

    Science.gov (United States)

    Skov, Søren Nielsen; Røpcke, Diana Mathilde; Ilkjær, Christine; Rasmussen, Jonas; Tjørnild, Marcell Juan; Jimenez, Jorge H; Yoganathan, Ajit P; Nygaard, Hans; Nielsen, Sten Lyager; Jensen, Morten Olgaard

    2016-03-21

    Limited knowledge exists about the forces acting on mitral valve annuloplasty repair devices. The aim of this study was to develop a new mitral annular force transducer to measure the forces acting on clinically used mitral valve annuloplasty devices. The design of an X-shaped transducer in the present study was optimized for simultaneous in- and out-of-plane force measurements. Each arm was mounted with strain gauges on four circumferential elements to measure out-of-plane forces, and the central parts of the X-arms were mounted with two strain gauges to measure in-plane forces. A dedicated calibration setup was developed to calibrate isolated forces with tension and compression for in- and out-of-plane measurements. With this setup, it was possible with linear equations to isolate and distinguish measured forces between the two planes and minimize transducer arm crosstalk. An in-vitro test was performed to verify the crosstalk elimination method and the assumptions behind it. The force transducer was implanted and evaluated in an 80kg porcine in-vivo model. Following crosstalk elimination, in-plane systolic force accumulation was found to be in average 4.0±0.1N and the out-of-plane annular segments experienced an average force of 1.4±0.4N. Directions of the systolic out-of-plane forces indicated movements towards a saddle shaped annulus, and the transducer was able to measure independent directional forces in individual annular segments. Further measurements with the new transducer coupled with clinical annuloplasty rings will provide a detailed insight into the biomechanical dynamics of these devices. PMID:26903412

  7. New mitral annular force transducer optimized to distinguish annular segments and multi-plane forces.

    Science.gov (United States)

    Skov, Søren Nielsen; Røpcke, Diana Mathilde; Ilkjær, Christine; Rasmussen, Jonas; Tjørnild, Marcell Juan; Jimenez, Jorge H; Yoganathan, Ajit P; Nygaard, Hans; Nielsen, Sten Lyager; Jensen, Morten Olgaard

    2016-03-21

    Limited knowledge exists about the forces acting on mitral valve annuloplasty repair devices. The aim of this study was to develop a new mitral annular force transducer to measure the forces acting on clinically used mitral valve annuloplasty devices. The design of an X-shaped transducer in the present study was optimized for simultaneous in- and out-of-plane force measurements. Each arm was mounted with strain gauges on four circumferential elements to measure out-of-plane forces, and the central parts of the X-arms were mounted with two strain gauges to measure in-plane forces. A dedicated calibration setup was developed to calibrate isolated forces with tension and compression for in- and out-of-plane measurements. With this setup, it was possible with linear equations to isolate and distinguish measured forces between the two planes and minimize transducer arm crosstalk. An in-vitro test was performed to verify the crosstalk elimination method and the assumptions behind it. The force transducer was implanted and evaluated in an 80kg porcine in-vivo model. Following crosstalk elimination, in-plane systolic force accumulation was found to be in average 4.0±0.1N and the out-of-plane annular segments experienced an average force of 1.4±0.4N. Directions of the systolic out-of-plane forces indicated movements towards a saddle shaped annulus, and the transducer was able to measure independent directional forces in individual annular segments. Further measurements with the new transducer coupled with clinical annuloplasty rings will provide a detailed insight into the biomechanical dynamics of these devices.

  8. Annular burnout data from rod bundle experiments

    International Nuclear Information System (INIS)

    Burnout data for annular flow in a rod bundle are presented for both transient and steady-state conditions. Tests were performed at the Oak Ridge National Laboratory in the Thermal Hydraulic Test Facility (THTF), a pressurized-water loop containing an electrically heated 64-rod bundle. The bundle configuration is typical of later generation pressurized-water reactors with 17 x 17 fuel arrays. Both axial and radial power profiles are flat. All experiments were carried out in upflow with subcooled inlet conditions, insuring accurate flow measurement. Conditions within the bundle were typical of those which could be encountered during a nuclear reactor loss-of-coolant accident. Level average fluid conditions within the test section were calculated using steady-state mass and energy conservation considerations for the steady-state tests and a transient, homogeneous, equilibrium computer code for the transient tests. Unlike tube dryout, burnout within a rod bundle does not necessarily occur at one distinct axial level. The location of individual rod dryout was determined by scanning rods axially and locating the position where rod superheat increased from approx. =0 to 30 K or greater. Thermocouple instrumentation within the bundle allows the location of dryout to be determined to within approximately +.5 cm for many of the tests

  9. The spatial distribution of silicon NCs and erbium ion clusters by simultaneous high-resolution energy filtered and Z-contrast STEM and transmission electron tomography

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Xiongyao; Lockwood, Ross; Meldrum, Al [Department of Physics, University of Alberta, CEB, T6G2G7 Edmonton (Canada); Li, Peng; Malac, Marek [National Institute for Nanotechnology, National Research Council, Edmonton AB, T6G 2M9 (Canada)

    2011-03-15

    Imaging the spatial distribution of silicon nanocrystals (Si-NCs) and erbium ion clusters can assist in the development of light-emitting erbium-doped silicon nanocomposites. We applied simultaneous energy-filtered and high-angle annular dark field imaging in the scanning transmission electron microscopy (STEM) mode; the former method images the Si NCs and the latter is sensitive to the high atomic number of the Er{sup 3+} ions. Both methods were performed simultaneously so as to avoid relative image drift. In Er-doped Si nano-composites, we find that the Er ions are not uniformly distributed in the matrix: instead, they form clusters that appear in projection images to decorate the boundaries of the Si-NCs. This structure may develop during sample annealing, due to the low solubility of Er in the forming Si clusters. Although multi-detector simultaneous imaging is a good way to avoid nanometer-scale image drift that could otherwise conceal the nanoscale spatial relationship between Si-NCs and Er clusters, an additional difficulty relates to the projection imaging methods. Essentially, it is hard to obtain spatial information parallel to the electron beam direction, so where there is apparent overlap we cannot ascertain whether an Er cluster (for example) lies above, below, or inside a given Si-NC. Therefore, we also report on initial electron beam tomography investigations whose goal is ultimately to generate methods for obtaining the Er and Si cluster distribution in 3D. The results can lead to improved understanding of the sensitization mechanism and optimization for Er-doped silicon nanocomposites; the clustered nature of the Er ions near the Si NCs is certainly undesirable and may explain the typically short Er{sup 3+} photoluminescence (PL) lifetimes (compared to Er-doped silica) and the difficulty in reliably observing stimulated emission phenomena (copyright 2011 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  10. X-ray diffraction from bone employing annular and semi-annular beams

    International Nuclear Information System (INIS)

    There is a compelling need for accurate, low cost diagnostics to identify osteo-tissues that are associated with a high risk of fracture within an individual. To satisfy this requirement the quantification of bone characteristics such as ‘bone quality’ need to exceed that provided currently by densitometry. Bone mineral chemistry and microstructure can be determined from coherent x-ray scatter signatures of bone specimens. Therefore, if these signatures can be measured, in vivo, to an appropriate accuracy it should be possible by extending terms within a fracture risk model to improve fracture risk prediction.In this preliminary study we present an examination of a new x-ray diffraction technique that employs hollow annular and semi-annular beams to measure aspects of ‘bone quality’. We present diffractograms obtained with our approach from ex vivo bone specimens at Mo Kα and W Kα energies. Primary data is parameterized to provide estimates of bone characteristics and to indicate the precision with which these can be determined. (paper)

  11. Precision improvement in dark-field microscopy imaging by using gold nanoparticles as an internal reference: a combined theoretical and experimental study

    Science.gov (United States)

    Ma, Jun; Liu, Yue; Gao, Peng Fei; Zou, Hong Yan; Huang, Cheng Zhi

    2016-04-01

    Low accuracy is a big obstacle in the dark-field microscopy imaging (iDFM) technique in practical applications. In order to reduce the deviations and fluctuations in the observed or snapped scattered light in the iDFM technique caused by unavoidable measurement errors, bare gold nanoparticles (AuNPs) were introduced as an internal reference (IR). The feasibility of using AuNPs as the IR in iDFM in theory was verified. The function of the IR in improving the precision of the acquired data through post data analysis was identified by three kinds of experiments: monitoring the oxidation process of silver nanoparticles (AgNPs) at room temperature, quantifying the level of glucose with AgNPs used as probes and quantifying the change in the light intensity of AuNPs after the plasmon resonance energy transfer (PRET) between AuNPs and tetramethylrhodamine (TAMRA).Low accuracy is a big obstacle in the dark-field microscopy imaging (iDFM) technique in practical applications. In order to reduce the deviations and fluctuations in the observed or snapped scattered light in the iDFM technique caused by unavoidable measurement errors, bare gold nanoparticles (AuNPs) were introduced as an internal reference (IR). The feasibility of using AuNPs as the IR in iDFM in theory was verified. The function of the IR in improving the precision of the acquired data through post data analysis was identified by three kinds of experiments: monitoring the oxidation process of silver nanoparticles (AgNPs) at room temperature, quantifying the level of glucose with AgNPs used as probes and quantifying the change in the light intensity of AuNPs after the plasmon resonance energy transfer (PRET) between AuNPs and tetramethylrhodamine (TAMRA). Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08837b

  12. A machine vision system for automated non-invasive assessment of cell viability via dark field microscopy, wavelet feature selection and classification

    Directory of Open Access Journals (Sweden)

    Friehs Karl

    2008-10-01

    Full Text Available Abstract Background Cell viability is one of the basic properties indicating the physiological state of the cell, thus, it has long been one of the major considerations in biotechnological applications. Conventional methods for extracting information about cell viability usually need reagents to be applied on the targeted cells. These reagent-based techniques are reliable and versatile, however, some of them might be invasive and even toxic to the target cells. In support of automated noninvasive assessment of cell viability, a machine vision system has been developed. Results This system is based on supervised learning technique. It learns from images of certain kinds of cell populations and trains some classifiers. These trained classifiers are then employed to evaluate the images of given cell populations obtained via dark field microscopy. Wavelet decomposition is performed on the cell images. Energy and entropy are computed for each wavelet subimage as features. A feature selection algorithm is implemented to achieve better performance. Correlation between the results from the machine vision system and commonly accepted gold standards becomes stronger if wavelet features are utilized. The best performance is achieved with a selected subset of wavelet features. Conclusion The machine vision system based on dark field microscopy in conjugation with supervised machine learning and wavelet feature selection automates the cell viability assessment, and yields comparable results to commonly accepted methods. Wavelet features are found to be suitable to describe the discriminative properties of the live and dead cells in viability classification. According to the analysis, live cells exhibit morphologically more details and are intracellularly more organized than dead ones, which display more homogeneous and diffuse gray values throughout the cells. Feature selection increases the system's performance. The reason lies in the fact that feature

  13. Practical aspects of strain measurement in thin SiGe layers by (004) dark-field electron holography in Lorentz mode.

    Science.gov (United States)

    Denneulin, T; Cooper, D; Rouviere, J L

    2014-07-01

    Dark-field electron holography (DFEH) is a powerful transmission electron microscopy technique for mapping strain with nanometer resolution and high precision. However the technique can be difficult to set up if some practical steps are not respected. In this article, several measurements were performed on thin Si(1-x)Gex layers using (004) DFEH in Lorentz mode. Different practical aspects are discussed such as sample preparation, reconstruction of the holograms and interpretation of the strain maps in terms of sensitivity and accuracy. It was shown that the measurements are not significantly dependent on the preparation tool. Good results can be obtained using both FIB and mechanical polishing. Usually the most important aspect is a precise control of the thickness of the sample. A problem when reconstructing (004) dark-field holograms is the relatively high phase gradient that characterises the strained regions. It can be difficult to perform reconstructions with high sensitivity in both strained and unstrained regions. Here we introduce simple methods to minimise the noise in the different regions using a specific mask shape in Fourier space or by combining several reconstructions. As a test, DFEH was applied to the characterization of eight Si(1-x)Gex samples with different Ge concentrations. The sensitivity of the strain measured in the layers varies between 0.08% and 0.03% for spatial resolutions of 3.5-7 nm. The results were also compared to finite element mechanical simulations. A good accuracy of ±0.1% between experiment and simulation was obtained for strains up to 1.5% and ±0.25% for strains up to 2.5%.

  14. Sea Carousel—A benthic, annular flume

    Science.gov (United States)

    Amos, Carl L.; Grant, J.; Daborn, G. R.; Black, K.

    1992-06-01

    A benthic annular flume (Sea Carousel) has been developed and tested to measure in situ the erodibility of cohesive sediments. The flume is equipped with three optical backscatter sensors, a lid rotation switch, and an electromagnetic (EM) flow meter capable of detecting azimuthal and vertical components of flow. Data are logged at rates up to 10·66 Hz. Erodibility is inferred from the rate of change in suspended sediment concentration detected in the annulus. The energy-density/wave number spectrum of azimuthal flow showed peaks in the energy spectrum at paddle rotation wave numbers (k) of 14 and 7 m -1 (macroturbulent time scales) but were not significant. Friction velocity ( U*), measured (1) at 1 Hz using a flush-mounted hot-film sensor, and (2) derived from measured velocity profiles in the inner part of the logarithmic layer gave comparable results for Ū* 0·32 m s -1. Radial velocity gradients were proportional to ( Ū y - 0·32 m s -1). Maximum radial differences in U* were 10% for Ū y = 0·5 ms -1. Suspended sediment mass concentration ( S) in the annulus resulted in a significant decrease (10·5%) in Ū* derived by method (1) over the range 0calibration with changes in S. Subaerial deployments of Sea Carousel caused severe substrate disturbance, water losses, and aeration of the annulus. Submarine deployments produced stable results, though dispersion of turbid flume water took place. Results clearly demonstrated the existence of 'Type I' and 'Type II' erosion documented from laboratory studies.

  15. Far-field Diffraction Properties of Annular Walsh Filters

    Directory of Open Access Journals (Sweden)

    Pubali Mukherjee

    2013-01-01

    Full Text Available Annular Walsh filters are derived from the rotationally symmetric annular Walsh functions which form a complete set of orthogonal functions that take on values either +1 or −1 over the domain specified by the inner and outer radii of the annulus. The value of any annular Walsh function is taken as zero from the centre of the circular aperture to the inner radius of the annulus. The three values 0, +1, and −1 in an annular Walsh function can be realized in a corresponding annular Walsh filter by using transmission values of zero amplitude (i.e., an obscuration, unity amplitude and zero phase, and unity amplitude and phase, respectively. Not only the order of the Walsh filter but also the size of the inner radius of the annulus provides an additional degree of freedom in tailoring of point spread function by using these filters for pupil plane filtering in imaging systems. In this report, we present the far-field amplitude characteristics of some of these filters to underscore their potential for effective use in several demanding applications like high-resolution microscopy, optical data storage, microlithography, optical encryption, and optical micromanipulation.

  16. Stem Cells

    Science.gov (United States)

    Stem cells are cells with the potential to develop into many different types of cells in the body. They serve as a repair ... body. There are two main types of stem cells: embryonic stem cells and adult stem cells. Stem ...

  17. Fluidic Analysis in an Annular Centrifugal Contactor for Fuel Reprocessing

    International Nuclear Information System (INIS)

    An annular centrifugal contactor (ACC) is a promising device for fuel reprocessing process, because it offers several advantages—a smaller size, a smaller holdup volume, and a higher separation performance—over conventional contactors such as a mixer-settler and a pulse column. Fluid dynamics and dispersion in an ACC, which has a combined mixer/centrifuge structure, are closely related to its separation performance and capacity, and this information is useful in improving equipment design. In this paper, experimental and computational fluid dynamics (CFD) studies were conducted to analyze fluidic and dispersion behavior in ACCs. Multiphase mixing (water/TBP-dodecane/air) in the annular zone was observed by Particle Imaging Velocimetry, and the change in the fluidic and dispersion behavior was ascertained under several operational conditions. The results of the CFD studies, which considered multiphase turbulent flow in the annular and rotor interior zones, were in a good agreement with the experimental data. (author)

  18. Annular lupus vulgaris: an unusual case undiagnosed for five years.

    Science.gov (United States)

    Gönül, Müzeyyen; Kiliç, Arzu; Külcü Cakmak, Seray; Gül, Ulker; Koçak, Oğuzhan; Demiriz, Murat

    2007-01-01

    Tuberculosis is still a serious problem in both developing and developed countries. It is often confused with various cutaneous disorders both clinically and histopathologically.A 46-year-old woman attended our clinic with progressive, asymptomatic, annular skin lesions on her right upper extremity for 5 years. She had received many different therapies for these lesions at other institutions previously but these medications were not effective and the lesions deteriorated. On dermatological examination, well-demarcated, irregular bordered, violaceous colored, elevated and crusted annular lesions on her right hand dorsum and forearm were observed. She was diagnosed as having lupus vulgaris clinically and histopathologically. Antituberculosis therapy was administered and regression of the lesions started in the second week of medication.We report a case of long-standing, undiagnosed and uncommon, annular form of lupus vulgaris. We want to stress that clinical and histopathological findings are still important for the diagnosis of cutaneous tuberculosis.

  19. Vibration Analysis of Annular Sector Plates under Different Boundary Conditions

    Directory of Open Access Journals (Sweden)

    Dongyan Shi

    2014-01-01

    Full Text Available An analytical framework is developed for the vibration analysis of annular sector plates with general elastic restraints along each edge of plates. Regardless of boundary conditions, the displacement solution is invariably expressed as a new form of trigonometric expansion with accelerated convergence. The expansion coefficients are treated as the generalized coordinates and determined using the Rayleigh-Ritz technique. This work allows a capability of modeling annular sector plates under a variety of boundary conditions and changing the boundary conditions as easily as modifying the material properties or dimensions of the plates. Of equal importance, the proposed approach is universally applicable to annular sector plates of any inclusion angles up to 2π. The reliability and accuracy of the current method are adequately validated through numerical examples.

  20. Mathematical Model of Combustion in Blunt Annular Ceramic Burner

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    The computer simulation of the combustion process in blast furnace (BF) stove has been studied by using the k-ε-g turbulent diffusion flame model. The combustion process in blunt annular ceramic burner was calculated by using the software. The profiles of gas and air velocity, temperature of the combustion products, concentration of the components, and the shape and length of the flame during combustion have been researched . Compared with the original annular ceramic burner, the new design of the blunt one improves the mixing of the gas and the air significantly, and shortened the length of the flame.

  1. Mitral-aortic annular enlargement: modification of Manouguian's technique

    Directory of Open Access Journals (Sweden)

    Costa Mario Gesteira

    2002-01-01

    Full Text Available We hereby present a technical modification for mitral-aortic annular enlargement. The mitral valve is replaced through the retro-septal approach, avoiding patches for left atrial roof closure. We report a mitral-aortic valve replacement in a patient whose original annuli would preclude adequate prostheses. The simultaneous annular enlargement may be necessary for avoiding patient-prosthesis mismatch and for reconstructing destroyed mitral and aortic annuli. The technique may minimize the risk of bleeding and of paravalvular leakage, using an approach well known to cardiac surgeons.

  2. Portal annular pancreas: the pancreatic duct ring sign on MRCP.

    Science.gov (United States)

    Lath, Chinar O; Agrawal, Dilpesh S; Timins, Michael E; Wein, Melissa M

    2015-12-01

    Portal annular pancreas is a rare pancreatic variant in which the uncinate process of the pancreas extends and fuses to the dorsal surface of the body of the pancreas by surrounding the portal vein. It is asymptomatic, but it can be mistaken for a pancreatic head mass on imaging and could also have serious consequences during pancreatic surgery, if unrecognized. We report this case of a 53-year-old female patient who was diagnosed to have portal annular pancreas on the basis of an unusual course (ring appearance) of the main pancreatic duct on magnetic resonance cholangiopancreatography, not described earlier in the radiology literature. PMID:26649117

  3. Portal annular pancreas: the pancreatic duct ring sign on MRCP

    Directory of Open Access Journals (Sweden)

    Chinar O. Lath, MD

    2015-12-01

    Full Text Available Portal annular pancreas is a rare pancreatic variant in which the uncinate process of the pancreas extends and fuses to the dorsal surface of the body of the pancreas by surrounding the portal vein. It is asymptomatic, but it can be mistaken for a pancreatic head mass on imaging and could also have serious consequences during pancreatic surgery, if unrecognized. We report this case of a 53-year-old female patient who was diagnosed to have portal annular pancreas on the basis of an unusual course (ring appearance of the main pancreatic duct on magnetic resonance cholangiopancreatography, not described earlier in the radiology literature.

  4. Flow Visualisation of Annular Liquid Sheet Instability & Atomisation

    CERN Document Server

    Duke, Daniel; Soria, Julio

    2012-01-01

    Fluid dynamics videos of unstable thin annular liquid sheets are presented in this short paper. These videos are to be presented in the Gallery of Fluid Motion for the American Physical Society 65th Annual Meeting of the Division of Fluid Dynamics in San Diego, CA, 18-20 November 2012. An annular sheet of thickness h=1mm and mean radius R=18.9mm is subjected to aerodynamic axial shear from co-flowing air at various shear rates on both the inner and outer surface at a liquid sheet Reynolds Number of Re=500.

  5. Patch Type Granuloma Annulare Imitating Cutaneous T-Cell Lymphoma

    Directory of Open Access Journals (Sweden)

    Seval Doğruk Kaçar

    2015-03-01

    Full Text Available Granuloma annulare (GA is a benign inflammatory skin disease with distinct clinical and histopathological findings. Patch type GA is described with erythematous patches beyond the classical clinical appearance and an interstitial pattern is observed without histopathologically granulomas with disseminated histiocytes among collagen bundles and vessels. Here we report 46 year old woman diagnosed as patch type GA after a punch biopsy performed from the annular bordered patches in belly area, which is a classical area for mycosis fungoides (MF evolution, and lesions increasingly spreading out within a 2 year period.

  6. STEM, STEM Education, STEMmania

    OpenAIRE

    Sanders, Mark E.

    2008-01-01

    A series of circumstances has once more created an opportunity for technology educators to develop and implement new integrative approaches to STEM education championed by STEM education reform doctrine over the past two decades.

  7. Design curves for circular and annular duct silencers

    Science.gov (United States)

    Watson, Willie R.; Ramakrishnan, R.

    1989-01-01

    Conventional models of sound propagation between porous walls (Scott, 1946) are adapted in order to calculate design curves for the lined circular and annular-duct silencers used in HVAC systems. The derivation of the governing equations is outlined, and results for two typical cases are presented graphically. Good agreement with published experimental data is demonstrated.

  8. Improvement of image processing algorithms for annular flow

    International Nuclear Information System (INIS)

    Annular flow occurs in a wide range of industrial heat-transfer equipment, including the top of a BWR core, in the steam generator of a PWR, and in postulated accident scenarios including critical heat flux (CHF) by dryout. The modeling of annular flow often requires information regarding the average thickness of liquid film at the periphery of the flow channel as a measurement of film roughness (film roughness concept). More recently, two-region modeling efforts require wave intermittency as a measurement of disturbance wave (as opposed to base film thickness) contribution to gas-to-liquid momentum transfer and pressure loss. The present work focuses on the characterization of film behaviors in annular flow using quantitative visualization. The data reduction codes for planar laser-induced flourescence (PLIF) imaging and back-lit quartz tube imaging have been further developed to improve measurement accuracy. Film thickness distribution (base film and wave), disturbance wave length, and wave intermittency estimates have been updated and applied to a recent two-region annular flow model. Outputs of average film thickness, pressure gradient, and average wave velocity have been modeled with mean absolute errors of 8.70%, 17.42%, and 19.14%, respectively. (author)

  9. Flow of viscoplastic fluids in eccentric annular geometries

    DEFF Research Database (Denmark)

    Szabo, Peter; Hassager, Ole

    1992-01-01

    A classification of flowfields for the flow of a Bingham fluid in general eccentric annular geometries is presented. Simple arguments show that a singularity can exist in the stress gradient on boundaries between zones with yielded and un-yielded fluid respectively. A Finite Element code is used ...

  10. Crystal analyser-based X-ray phase contrast imaging in the dark field: implementation and evaluation using excised tissue specimens

    Energy Technology Data Exchange (ETDEWEB)

    Ando, Masami [RIST, Tokyo University of Science, Noda, Chiba (Japan); Sunaguchi, Naoki [Gunma University, Graduate School of Engineering, Kiryu, Gunma (Japan); Wu, Yanlin [The Graduate University for Advanced Studies, Department of Materials Structure Science, School of High Energy Accelerator Science, Tsukuba, Ibaraki (Japan); Do, Synho; Sung, Yongjin; Gupta, Rajiv [Massachusetts General Hospital and Harvard Medical School, Department of Radiology, Boston, MA (United States); Louissaint, Abner [Massachusetts General Hospital and Harvard Medical School, Department of Pathology, Boston, MA (United States); Yuasa, Tetsuya [Yamagata University, Faculty of Engineering, Yonezawa, Yamagata (Japan); Ichihara, Shu [Nagoya Medical Center, Department of Pathology, Nagoya, Aichi (Japan)

    2014-02-15

    We demonstrate the soft tissue discrimination capability of X-ray dark-field imaging (XDFI) using a variety of human tissue specimens. The experimental setup for XDFI comprises an X-ray source, an asymmetrically cut Bragg-type monochromator-collimator (MC), a Laue-case angle analyser (LAA) and a CCD camera. The specimen is placed between the MC and the LAA. For the light source, we used the beamline BL14C on a 2.5-GeV storage ring in the KEK Photon Factory, Tsukuba, Japan. In the eye specimen, phase contrast images from XDFI were able to discriminate soft-tissue structures, such as the iris, separated by aqueous humour on both sides, which have nearly equal absorption. Superiority of XDFI in imaging soft tissue was further demonstrated with a diseased iliac artery containing atherosclerotic plaque and breast samples with benign and malignant tumours. XDFI on breast tumours discriminated between the normal and diseased terminal duct lobular unit and between invasive and in-situ cancer. X-ray phase, as detected by XDFI, has superior contrast over absorption for soft tissue processes such as atherosclerotic plaque and breast cancer. (orig.)

  11. Crystal analyser-based X-ray phase contrast imaging in the dark field: implementation and evaluation using excised tissue specimens

    International Nuclear Information System (INIS)

    We demonstrate the soft tissue discrimination capability of X-ray dark-field imaging (XDFI) using a variety of human tissue specimens. The experimental setup for XDFI comprises an X-ray source, an asymmetrically cut Bragg-type monochromator-collimator (MC), a Laue-case angle analyser (LAA) and a CCD camera. The specimen is placed between the MC and the LAA. For the light source, we used the beamline BL14C on a 2.5-GeV storage ring in the KEK Photon Factory, Tsukuba, Japan. In the eye specimen, phase contrast images from XDFI were able to discriminate soft-tissue structures, such as the iris, separated by aqueous humour on both sides, which have nearly equal absorption. Superiority of XDFI in imaging soft tissue was further demonstrated with a diseased iliac artery containing atherosclerotic plaque and breast samples with benign and malignant tumours. XDFI on breast tumours discriminated between the normal and diseased terminal duct lobular unit and between invasive and in-situ cancer. X-ray phase, as detected by XDFI, has superior contrast over absorption for soft tissue processes such as atherosclerotic plaque and breast cancer. (orig.)

  12. Magnetization Response of the Bulk and Supplementary Magnetic Domain Structure in High-Permeability Steel Laminations Visualized In Situ by Neutron Dark-Field Imaging

    Science.gov (United States)

    Betz, B.; Rauscher, P.; Harti, R. P.; Schäfer, R.; Irastorza-Landa, A.; Van Swygenhoven, H.; Kaestner, A.; Hovind, J.; Pomjakushina, E.; Lehmann, E.; Grünzweig, C.

    2016-08-01

    Industrial transformer cores are composed of stacked high-permeability steel laminations (HPSLs). The performance and degree of efficiency of transformers are directly determined by the magnetic properties of each HPSL. In this article, we show how the neutron dark-field image (DFI) allows for the in situ visualization of the locally resolved response of the bulk and supplementary magnetic domain structures in HPSLs under the influence of externally applied magnetic fields. In particular, we investigate the domain formation and growth along the initial magnetization curve up to the saturated state. For decreasing field, we visualize the recurrence of the hysteretic domain structure down to the remanent state. Additionally, the DFI allows us to derive a correlation between the grain orientation and the corresponding volume and supplementary domain structure. Furthermore, we visualize the influence of the insulation coating, introducing desired tensile stresses on the domain structures. To compare our DFI findings to traditional methods, we perform complementary surface-sensitive magneto-optical Kerr-microscopy investigations.

  13. Shift-and-add tomosynthesis of a finger joint by X-ray dark-field imaging: Difference due to tomographic angle

    International Nuclear Information System (INIS)

    A tomogram of a finger joint showing articular cartilage was generated based on X-ray dark-field imaging (XDFI) using the shift-and-add tomosynthesis algorithm. The experiment was performed at beamline 14B of the Photon Factory in Tsukuba, Japan, using synchrotron X-rays from a vertical wiggler. The incident X-ray energy was 36.0 keV. The X-ray optics for XDFI comprised two Si crystals: an asymmetric cut Si (2 2 0) monochromator-collimator and a 1.1-mm thick Si (2 2 0) Laue-case analyzer. The object was an intact cadaveric proximal interphalangeal joint fixed in formalin. Raw projection data were acquired by XDFI in a total of 41 views through an angle of 20 deg. in 0.5 deg. increments. The object and detector were synchronously rotated such that the fulcrum plane in the object and detector plane remained parallel. The X-ray dose for one piece of raw projection data was set to one-eleventh of that for one standard projection image by XDFI. Eleven views through an angle of 10 deg. in increments of 1 deg. of all 41 appropriately shifted raw projection data were added to produce arbitrary tomograms parallel to the fulcrum plane. We obtained a clear tomogram of the finger joint including the articular cartilage with the moderate artifact peculiar to tomosynthesis. Consequently, arbitrary tomograms can be obtained for the same X-ray dose as that received for one standard projection image by XDFI. The fact that an inner structure such as articular cartilage, which is invisible to conventional X-ray imaging methods, has been visualized on a tomogram with preserved refraction-enhanced contrast, is of considerable significance to clinical medicine

  14. Optical dark field and electron energy loss imaging and spectroscopy of symmetry-forbidden modes in loaded nanogap antennas (Presentation Recording)

    Science.gov (United States)

    Brintlinger, Todd; Herzing, Andrew; Long, James P.; Vurgaftman, Igor; Stroud, Rhonda; Simpkins, Blake S.

    2015-09-01

    Theoretical work has identified a new type of hybrid nanoresonator akin to a loaded-gap antenna, wherein the gap between two collinearly aligned metal nanorods is filled with active dielectric material. The gap optical load has a profound impact on resonances supported by such a "nanogap" antenna, and thus provides opportunity for (i) active modulation of the antenna resonance and (ii) delivery of substantial energy to the gap material. To this end, we have (i) used a bottom-up technique to fabricate nanogap antennas (Au/CdS/Au); (ii) characterized the optical modes of individual antennas with polarization- and wavevector-controlled dark-field microscopy; (iii) mapped the spatial profiles of the dominant modes with electron energy loss spectroscopy and imaging; and (iv) utilized full-wave finite-difference time-domain simulations to reveal the nanoscopic origin of the radiating modes supported on such nanogap antennas. In addition to conventional transverse and longitudinal resonances, these loaded nanogap antennas support a unique symmetry-forbidden gap-localized transverse mode arising from the splitting of degenerate transverse modes located on the two gap faces. This previously unobserved mode is strong (E2 enhanced ~20), tightly localized in the nanoscopic (~30 nm separation) gap region, and is shown to red-shift with decreased gap size and increased gap dielectric constant. In fact, the mode is highly suppressed in air-gapped structures which may explain its absence from the literature to date. Understanding the complex modal structure supported on hybrid nanosystems is necessary to enable the multi-functional components many seek.

  15. Augmented 3D super-resolution of fluorescence-free nanoparticles using enhanced dark-field illumination based on wavelength-modulation and a least-cubic algorithm

    Science.gov (United States)

    Zhang, Peng; Kim, Kyungsoo; Lee, Seungah; Chakkarapani, Suresh Kumar; Fang, Ning; Kang, Seong Ho

    2016-09-01

    Augmented three-dimensional (3D) subdiffraction-limited resolution of fluorescence-free single-nanoparticles was achieved with wavelength-dependent enhanced dark-field (EDF) illumination and a least-cubic algorithm. Various plasmonic nanoparticles on a glass slide (i.e., gold nanoparticles, GNPs; silver nanoparticles, SNPs; and gold nanorods, GNRs) were imaged and sliced in the z-direction to a thickness of 10 nm. Single-particle images were then compared with simulation data. The 3D coordinates of individual GNP, SNP, and GNR nanoparticles (x, y, z) were resolved by fitting the data with 3D point spread functions using a least-cubic algorithm and collation. Final, 3D super-resolution microscopy (SRM) images were obtained by resolving 3D coordinates and their Cramér-Rao lower bound-based localization precisions in an image space (530 nm × 530 nm × 300 nm) with a specific voxel size (2.5 nm × 2.5 nm × 5 nm). Compared with the commonly used least-square method, the least-cubic method was more useful for finding the center in asymmetric cases (i.e., nanorods) with high precision and accuracy. This novel 3D fluorescence-free SRM technique was successfully applied to resolve the positions of various nanoparticles on glass and gold nanospots (in vitro) as well as in a living single cell (in vivo) with subdiffraction limited resolution in 3D.

  16. Quantitative analysis of interfacial strain in InAs/GaSb superlattices by aberration-corrected HRTEM and HAADF-STEM

    Energy Technology Data Exchange (ETDEWEB)

    Mahalingam, Krishnamurthy, E-mail: Krishnamurthy.Mahalingam.ctr@wpafb.af.mil [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7707 (United States); Haugan, Heather J.; Brown, Gail J.; Eyink, Kurt G. [Air Force Research Laboratory, Wright-Patterson AFB, OH 45433-7707 (United States)

    2013-04-15

    The strain distribution across interfaces in InAs/GaSb superlattices grown on (100)-GaSb substrates is investigated by aberration corrected transmission electron microscopy. Atomic resolution images of interfaces were obtained by conventional high resolution transmission electron microscopy (HRTEM), using the negative spherical-aberration imaging mode, and by scanning transmission electron microscopy (STEM), using the high-angle annular dark-field (HAADF) imaging mode. The local atomic displacements across interfaces were determined from these images using the peak pair algorithm, from which strain maps were calculated with respect to a reference lattice extracted from the GaSb substrate region. Both techniques yield consistent results, which reveal that the InAs-on-GaSb interface is nearly strain balanced, whereas the GaSb-on-InAs interface is in tensile strain, indicating that the prevalent bond type at this interface is Ga–As. In addition, the GaSb layers in the superlattice are compressively strained indicating the incorporation of In into these layers. Further analysis of the HAADF-STEM images indicates an estimated 4% In content in the GaSb layers and that the GaSb-on-InAs interface contributes to about 27% of the overall superlattice strain. The strain measurements in the InAs layers are in good agreement with the theoretical values determined from elastic constants. Furthermore, the overall superlattice strain determined from this analysis is also in good agreement with the measurements determined by high-resolution X-ray diffraction. - Highlights: ►The strain distribution across interfaces in InAs–GaSb superlattices is examined. ► The GaSb-on-InAs interfaces are tensile, accounting for 27% of the overall strain. ► The InAs-on-GaSb interfaces are strain neutral. ► The GaSb layers are in compressive strain due to indium incorporation of about 4%. ► The strain in InAs layers is tensile, and is close to the bulk value of about 1%.

  17. Production of annular flat-topped vortex beams

    Institute of Scientific and Technical Information of China (English)

    Jiannong Chen; Yongjiang Yu; Feifei Wang

    2011-01-01

    @@ A model of an annular flat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The power of the beam is concentrated on a single-ring structure and has an extremely strong radial intensity gradient. This beam facilitates various applications ranging from Sisyphus atom cooling to micro-particle trapping.%A model of an annular fiat-topped vortex beam based on multi-Gaussian superimposition is proposed. We experimentally produce this beam with a computer-generated hologram (CGH) displayed on a spatial light modulator (SLM). The power of the beam is concentrated on a single-ring structure and has an extremely strong radial intensity gradient. This beam facilitates various applications ranging from Sisyphus atom cooling to micro-particle trapping.

  18. Energy and Exergy Analysis of an Annular Thermoelectric Heat Pump

    Science.gov (United States)

    Kaushik, S. C.; Manikandan, S.; Hans, Ranjana

    2016-07-01

    In this paper, the concept of an annular thermoelectric heat pump (ATEHP) has been introduced. An exoreversible thermodynamic model of the ATEHP considering the Thomson effect in conjunction with Peltier, Joule and Fourier heat conduction has been investigated using exergy analysis. New expressions for dimensionless heating power, optimum current at the maximum energy, exergy efficiency conditions and dimensionless irreversibilities in the ATEHP are derived. The results show that the heating power, energy and exergy efficiency of the ATEHP are lower than the flat-plate thermoelectric heat pump. The effects of annular shape parameter ( S r = r 2 /r 1), dimensionless temperature ratio ( θ = T h /T c) and the electrical contact resistances on the heating power, energy/exergy efficiency of an ATEHP have been studied. This study will help in the designing of actual ATEHP systems.

  19. Electroosmotic flow and Joule heating in preparative continuous annular electrochromatography.

    Science.gov (United States)

    Laskowski, René; Bart, Hans-Jörg

    2015-09-01

    An openFOAM "computational fluid dynamic" simulation model was developed for the description of local interaction of hydrodynamics and Joule heating in annular electrochromatography. A local decline of electrical conductivity of the background eluent is caused by an electrokinetic migration of ions resulting in higher Joule heat generation. The model equations consider the Navier-Stokes equation for incompressible fluids, the energy equation for stationary temperature fields, and the mass transfer equation for the electrokinetic flow. The simulations were embedded in commercial ANSYS Fluent software and in open-source environment openFOAM. The annular gap (1 mm width) contained an inorganic C8 reverse-phase monolith as stationary phase prepared by an in situ sol-gel process. The process temperature generated by Joule heating was determined by thermal camera system. The local hydrodynamics in the prototype was detected by a gravimetric contact-free measurement method and experimental and simulated values matched quite well. PMID:25997390

  20. Analysis of a Low-Angle Annular Expander Nozzle

    Directory of Open Access Journals (Sweden)

    Kyll Schomberg

    2015-01-01

    Full Text Available An experimental and numerical analysis of a low-angle annular expander nozzle is presented to observe the variance in shock structure within the flow field. A RANS-based axisymmetric numerical model was used to evaluate flow characteristics and the model validated using experimental pressure readings and schlieren images. Results were compared with an equivalent converging-diverging nozzle to determine the capability of the wake region in varying the effective area of a low-angle design. Comparison of schlieren images confirmed that shock closure occurred in the expander nozzle, prohibiting the wake region from affecting the area ratio. The findings show that a low angle of deflection is inherently unable to influence the effective area of an annular supersonic nozzle design.

  1. Wind generated rogue waves in an annular wave flume

    CERN Document Server

    Toffoli, A; Salman, H; Monbaliu, J; Frascoli, F; Dafilis, M; Stramignoni, E; Forza, R; Manfrin, M; Onorato, M

    2016-01-01

    We investigate experimentally the statistical properties of a wind-generated wave field and the spontaneous formation of rogue waves in an annular flume. Unlike many experiments on rogue waves, where waves are mechanically generated, here the wave field is forced naturally by wind as it is in the ocean. What is unique about the present experiment is that the annular geometry of the tank makes waves propagating circularly in an {\\it unlimited-fetch} condition. Within this peculiar framework, we discuss the temporal evolution of the statistical properties of the surface elevation. We show that rogue waves and heavy-tail statistics may develop naturally during the growth of the waves just before the wave height reaches a stationary condition. Our results shed new light on the formation of rogue waves in a natural environment.

  2. Unusual Presentation of Acute Annular Urticaria: A Case Report

    OpenAIRE

    Gilles Guerrier; Jean-Marc Daronat; Roger Deltour

    2011-01-01

    Acute urticarial lesions may display central clearing with ecchymotic or haemorrhagic hue, often misdiagnosed as erythema multiforme, serum-sickness-like reactions, or urticarial vasculitis. We report a case of acute annular urticaria with unusual presentation occurring in a 20-month-old child to emphasize the distinctive morphologic manifestations in a single disease. Clinicians who care for children should be able to differentiate acute urticaria from its clinical mimics. A directed history...

  3. Ignition sequence of an annular multi-injector combustor

    OpenAIRE

    Philip, Maxime; Boileau, Matthieu; Vicquelin, Ronan; Schmitt, Thomas; Durox, Daniel; Bourgoin, Jean-François; Candel, Sébastien

    2013-01-01

    Ignition is a critical process in combustion systems. In aeronautical combustors, altitude relight capacities are required in case of accidental extinction of the chamber. A simultaneous study of light-round ignition in an annular multi-injector combustor has been performed on the experimental and numerical sides. This effort allows a unique comparison to assess the reliability of Large-Eddy Simulation (LES) in such a configuration. Results are presented in fluid dynamics videos.

  4. Large Eddy Simulation of thermoacoustic instabilities in annular combustion chambers

    OpenAIRE

    Wolf, Pierre

    2011-01-01

    Increasingly stringent regulations and the need to tackle rising fuel prices have placed great emphasis on the design of aeronautical gas turbines. This drive towards innovation has resulted sometimes in new concepts being prone to combustion instabilities. Combustion instabilities arise from the coupling of acoustics and combustion. In the particular field of annular combustion chambers, these instabilities often take the form of azimuthal modes. To predict these modes, one must consider the...

  5. Hydraulic forces caused by annular pressure seals in centrifugal pumps

    Science.gov (United States)

    Iino, T.; Kaneko, H.

    1980-01-01

    The hydraulic forces caused by annular pressure seals were investigated. The measured inlet and exit loss coefficients of the flow through the seals were much smaller than the conventional values. The results indicate that the damping coefficient and the inertia coefficient of the fluid film in the seal are not affected much by the rotational speed or the eccentricity of the rotor, though the stiffness coefficient seemed to be influenced by the eccentricity.

  6. Droplet sizes, dynamics and deposition in vertical annular flow

    International Nuclear Information System (INIS)

    The role of droplets in vertical upwards annular flow is investigated, focusing on the droplet size distributions, dynamics, and deposition phenomena. An experimental program was performed based on a new laser optical technique developed in these laboratories and implemented here for annular flow. This permitted the simultaneous measurement of droplet size, axial and radial velocity. The dependence of droplet size distributions on flow conditions is analyzed. The Upper-Log Normal function proves to be a good model for the size distribution. The mechanism controlling the maximum stable drop size was found to result from the interaction of the pressure fluctuations of the turbulent flow of the gas core with the droplet. The average axial droplet velocity showed a weak dependence on gas rates. This can be explained once the droplet size distribution and droplet size-velocity relationship are analyzed simultaneously. The surprising result from the droplet conditional analysis is that larger droplet travel faster than smaller ones. This dependence cannot be explained if the drag curves used do not take into account the high levels of turbulence present in the gas core in annular flow. If these are considered, then interesting new situations of multiplicity and stability of droplet terminal velocities are encountered. Also, the observed size-velocity relationship can be explained. A droplet deposition is formulated based on the particle inertia control. This permitted the calculation of rates of drop deposition directly from the droplet size and velocities data

  7. Guided Wave Annular Array Sensor Design for Improved Tomographic Imaging

    Science.gov (United States)

    Koduru, Jaya Prakash; Rose, Joseph L.

    2009-03-01

    Guided wave tomography for structural health monitoring is fast emerging as a reliable tool for the detection and monitoring of hotspots in a structure, for any defects arising from corrosion, crack growth etc. To date guided wave tomography has been successfully tested on aircraft wings, pipes, pipe elbows, and weld joints. Structures practically deployed are subjected to harsh environments like exposure to rain, changes in temperature and humidity. A reliable tomography system should take into account these environmental factors to avoid false alarms. The lack of mode control with piezoceramic disk sensors makes it very sensitive to traces of water leading to false alarms. In this study we explore the design of annular array sensors to provide mode control for improved structural tomography, in particular, addressing the false alarm potential of water loading. Clearly defined actuation lines in the phase velocity dispersion curve space are calculated. A dominant in-plane displacement point is found to provide a solution to the water loading problem. The improvement in the tomographic images with the annular array sensors in the presence of water traces is clearly illustrated with a series of experiments. An annular array design philosophy for other problems in NDE/SHM is also discussed.

  8. Treatment of generalized granuloma annulare - a systematic review.

    Science.gov (United States)

    Lukács, J; Schliemann, S; Elsner, P

    2015-08-01

    Granuloma annulare (GA) is a benign inflammatory skin disease. Localized GA is likely to resolve spontaneously, while generalized GA (GGA) is rare and may persist for decades. GGA usually is resistant to a variety of therapeutic modalities and takes a chronic course. The objective of this study was to summarize all reported treatments of generalized granuloma annulare. This is a systematic review based on MEDLINE, Embase and Cochrane Central Register search of articles in English and German and a manual search, between 1980 and 2013, to summarize the treatment of generalized granuloma annulare. Most medical literature on treatment of GGA is limited to individual case reports and small series of patients treated without a control group. Randomized controlled clinical studies are missing. Multiple treatment modalities for GGA were reported including topical and systemic steroids, PUVA, isotretinoin, dapsone, pentoxifylline, hydroxychloroquine, cyclosporine, IFN-γ, potassium iodide, nicotinamide, niacinamide, salicylic acid, dipyridamole, PDT, fumaric acid ester, etanercept, infliximab, adalimumab. While there are numerous case reports of successful treatments in the literature including surgical, medical and phototherapy options, well-designed, randomized, controlled clinical trials are required for an evidence-based treatment of GGA. PMID:25651003

  9. Experimental study on particles mixing in an annular spouted bed

    Energy Technology Data Exchange (ETDEWEB)

    Hao, Huang; Guoxin, Hu [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China); Fengchao, Wang [Science and Technology Development Office, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2008-02-15

    A novel annular spouted bed was developed and studied experimentally. The experiments were performed to examine the effects of feeding mode, air velocity and static bed height as well as particle size on particle mixing for different conditions in this device. The results show that feeding by a rotating cone greatly improves particle mixing by homogeneously projecting the particles into the annular bed. For feeding by a rotating cone, the time required to get uniform mixing laterally is shorten almost 10 times less than that for feeding at a fixed point. With increasing air velocity, the axial mixing speed increases more significantly than the lateral mixing speed. The static bed height has important effects on the uniformity of the final admixtures. With increasing static bed height, the degree of mixing of the final mixture (FDM) axially first decreases, then increases, but laterally, the FDM is monotone decreasing. The particles of small size are helpful to raise the mixing speed. In addition, the dead zone in the annular spouted bed was analyzed. (author)

  10. Experimental study on particles mixing in an annular spouted bed

    Energy Technology Data Exchange (ETDEWEB)

    Huang Hao [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China); Hu Guoxin [School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200030 (China)], E-mail: hugx@sjtu.edu.cn; Wang Fengchao [Science and Technology Development Office, Shanghai Jiao Tong University, Shanghai 200030 (China)

    2008-02-15

    A novel annular spouted bed was developed and studied experimentally. The experiments were performed to examine the effects of feeding mode, air velocity and static bed height as well as particle size on particle mixing for different conditions in this device. The results show that feeding by a rotating cone greatly improves particle mixing by homogeneously projecting the particles into the annular bed. For feeding by a rotating cone, the time required to get uniform mixing laterally is shorten almost 10 times less than that for feeding at a fixed point. With increasing air velocity, the axial mixing speed increases more significantly than the lateral mixing speed. The static bed height has important effects on the uniformity of the final admixtures. With increasing static bed height, the degree of mixing of the final mixture (FDM) axially first decreases, then increases, but laterally, the FDM is monotone decreasing. The particles of small size are helpful to raise the mixing speed. In addition, the dead zone in the annular spouted bed was analyzed.

  11. Pancreaticoduodenectomy for pancreas carcinoma occurring in the annular pancreas: report of a case

    OpenAIRE

    Kawaida, Hiromichi; KONO, Hiroshi; Watanabe, Mitsuaki; Maki, Akira; Amemiya, Hidetake; Matsuda, Masanori; Fujii, Hideki; Fukasawa, Mitsuharu; Takahashi, Ei; Sano, Katsuhiro; Inoue, Tomohiro

    2015-01-01

    The annular pancreas is a rare congenital anomaly in which a ring of the pancreas parenchyma surrounds the second part of the duodenum. Malignant tumors are extremely rare in patients with an annular pancreas. A 64-year-old man presented with appetite loss and vomiting. Abdominal contrast-enhanced computed tomography (CT) indicated pancreas parenchyma surrounding the second part of the duodenum, and a hypovascular area occupying lesion in the annular pancreas. Subtotal stomach-preserving panc...

  12. Repeated mitral valve replacement in a patient with extensive annular calcification

    OpenAIRE

    Kitamura Tadashi; Fukuda Sachito; Sawada Takahiro; Miura Sumio; Kigawa Ikutaro; Miyairi Takeshi

    2011-01-01

    Abstract Background Mitral valve replacement in the presence of severe annular calcification is a technical challenge. Case report A 47-year-old lady who had undergone mitral and aortic valve replacement for rheumatic disease 27 years before presented with dyspnea. At reoperation, extensive mitral annular calcification was hindering the disc motion of the Starr-Edwards mitral prosthesis. The old prosthesis was removed and a St Jude Medical mechanical valve was implanted after thorough annular...

  13. Pancreaticoduodenectomy for pancreas carcinoma occurring in the annular pancreas: report of a case.

    Science.gov (United States)

    Kawaida, Hiromichi; Kono, Hiroshi; Watanabe, Mitsuaki; Maki, Akira; Amemiya, Hidetake; Matsuda, Masanori; Fujii, Hideki; Fukasawa, Mitsuharu; Takahashi, Ei; Sano, Katsuhiro; Inoue, Tomohiro

    2015-08-01

    The annular pancreas is a rare congenital anomaly in which a ring of the pancreas parenchyma surrounds the second part of the duodenum. Malignant tumors are extremely rare in patients with an annular pancreas. A 64-year-old man presented with appetite loss and vomiting. Abdominal contrast-enhanced computed tomography (CT) indicated pancreas parenchyma surrounding the second part of the duodenum, and a hypovascular area occupying lesion in the annular pancreas. Subtotal stomach-preserving pancreaticoduodenectomy was performed. Histopathology showed pancreatic carcinoma occurring in the complete annular pancreas.

  14. An Annular Gap Acceleration Model for γ-ray Emission of Pulsars

    Institute of Scientific and Technical Information of China (English)

    2007-01-01

    If the binding energy of the pulsar's surface is not so high (the case of a neutron star), both negative and positive charges will flow out freely from the surface of the star. An annular free flow model for γ-ray emission of pulsars is suggested. It is emphasized that:(1) Two kinds of acceleration regions (annular and core) need to be taken into account. The annular acceleration region is defined by the magnetic field lines that cross the null charge surface within the light cylinder. (2) If the potential drop in the annular region of a pulsar is high enough (normally the case for young pulsars), charges in both the annular and the core regions could be accelerated and produce primary gamma-rays. Secondary pairs are generated in both regions and stream outwards to power the broadband radiations. (3) The potential drop grows more rapidly in the annular region than in the core region. The annular acceleration process is a key process for producing the observed wide emission beams. (4)The advantages of both the polar cap and outer gap models are retained in this model. The geometric properties of the γ-ray emission from the annular flow are analogous to that presented in a previous work by Qiao et al., which match the observations well. (5) Since charges with different signs leave the pulsar through the annular and the core regions respectively, the current closure problem can be partially solved.

  15. Electron beam diagnostic system using computed tomography and an annular sensor

    Science.gov (United States)

    Elmer, John W.; Teruya, Alan T.

    2014-07-29

    A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

  16. Electron beam diagnostic system using computed tomography and an annular sensor

    Energy Technology Data Exchange (ETDEWEB)

    Elmer, John W.; Teruya, Alan T.

    2015-08-11

    A system for analyzing an electron beam including a circular electron beam diagnostic sensor adapted to receive the electron beam, the circular electron beam diagnostic sensor having a central axis; an annular sensor structure operatively connected to the circular electron beam diagnostic sensor, wherein the sensor structure receives the electron beam; a system for sweeping the electron beam radially outward from the central axis of the circular electron beam diagnostic sensor to the annular sensor structure wherein the electron beam is intercepted by the annular sensor structure; and a device for measuring the electron beam that is intercepted by the annular sensor structure.

  17. Gap instability of laminar flows in eccentric annular channels

    Energy Technology Data Exchange (ETDEWEB)

    Piot, Estelle [Department of Mechanical Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5 (Canada); Tavoularis, Stavros, E-mail: stavros.tavoularis@uottawa.ca [Department of Mechanical Engineering, University of Ottawa, Ottawa, Ontario, K1N 6N5 (Canada)

    2011-11-15

    Research highlights: Black-Right-Pointing-Triangle The critical Reynolds number for flow instability in the narrow gap of an eccentric annular channel with a diameter ratio of 0.28 was determined experimentally. Black-Right-Pointing-Triangle The critical Reynolds number increases with increasing eccentricity in the range 0.5 to 0.8. Black-Right-Pointing-Triangle The 'gap instability' is attributed to the instability of the two shear layers forming on either side of the gap, as the basic flow has an azimuthal variation that contains two inflection points, thus being potentially linearly unstable. - Abstract: Flow visualization has demonstrated that the critical Reynolds number for flow instability in the narrow gap of an annular channel with a diameter ratio of about 0.28 increases with increasing eccentricity e in the range 0.5 < e < 0.8. The critical Reynolds numbers in the wide gap at all eccentricities and in the narrow gap for 0 < e < 0.5 seem to be insensitive to eccentricity. These observations and comparison of the frequencies of transverse flow oscillations at different Reynolds numbers and different eccentricities demonstrate that at least two distinct instability mechanisms are present in annular flows. The one of particular interest in this work arises in narrow gaps and is attributed to the instability of the two shear layers forming on either side of the gap. Linear stability analysis demonstrated that the basic flow in concentric annuli is stable for the considered diameter ratio and range of Reynolds numbers. In contrast, the basic flow in eccentric annuli has an azimuthal variation that contains two inflection points, thus being potentially linearly unstable.

  18. Annular burnout data from rod-bundle experiments

    International Nuclear Information System (INIS)

    Burnout data for annular flow in a rod bundle are presented for both transient and steady-state conditions. Tests were performed at the Oak Ridge National Laboratory in the Thermal Hydraulic Test Facility (THTF), a pressurized-water loop containing an electrically heated 64-rod bundle. The bundle configuration is typical of later generation pressurized-water reactors with 17 x 17 fuel arrays. Both axial and radial power profiles are flat. All experiments were carried out in upflow with subcooled inlet conditions, insuring accurate flow measurement. Conditions within the bundle were typical of those which could be encountered during a nuclear reactor loss-of-coolant accident

  19. Analysis of Cold Flowfield of Multi—Annular Opposed Jets

    Institute of Scientific and Technical Information of China (English)

    H.F.Zhao; G.C.Benelli

    1992-01-01

    The technique of the use of multi-annular opposed jets as different from using swirl and bluff body creates an excellent recirculation zone with desired size in a large space.The size of ecirculation,the magnitude of reverse velocity and turbulence intensity are much greater than those formed by bluff body.Factors affecting the flowfield include the velocity ration of the opposed jets to the primary air J.the diameter and construction of the opposed jet ring,secondary air velocity and configuration,and confined or unconfined flow condition and so on.This method is a promising way for flame stabilization in combustion technology.

  20. Unusual Presentation of Acute Annular Urticaria: A Case Report

    Directory of Open Access Journals (Sweden)

    Gilles Guerrier

    2011-01-01

    Full Text Available Acute urticarial lesions may display central clearing with ecchymotic or haemorrhagic hue, often misdiagnosed as erythema multiforme, serum-sickness-like reactions, or urticarial vasculitis. We report a case of acute annular urticaria with unusual presentation occurring in a 20-month-old child to emphasize the distinctive morphologic manifestations in a single disease. Clinicians who care for children should be able to differentiate acute urticaria from its clinical mimics. A directed history and physical examination can reliably orientate necessary diagnostic testing and allow for appropriate treatment.

  1. Coexistence of disseminated granuloma annulare and asymptomatic multiple myeloma

    Directory of Open Access Journals (Sweden)

    Şebnem Aktan

    2013-09-01

    Full Text Available Granuloma annulare (GA is a benign inflammatory dermatosis of unknown cause, characterized by necrobiotic dermal papules. Several morphologic forms of GA including localized, disseminated, linear, nodular, perforating, subcutaneous, pustular and arcuate dermal erythema have been reported in the literature. Disseminated GA, a rarely seen form, has been reported in association with some hematopoietic and solid malignancies; however, it has been suggested that the exact causative relationship between malignancy and GA is unclear. We present here a 66-year-old female patient with disseminated GA associated with asymptomatic multipl myeloma.

  2. Exhaust emissions of a double annular combustor: Parametric study

    Science.gov (United States)

    Schultz, D. F.

    1974-01-01

    A full scale double-annular ram-induction combustor designed for Mach 3.0 cruise operation was tested. Emissions of oxides of nitrogen, carbon monoxide, unburned hydrocarbons, and smoke were measured over a range of combustor operating variables including reference velocity, inlet air temperature and pressure, and exit average temperature. ASTM Jet-A fuel was used for these tests. An equation is provided relating oxides of nitrogen emissions as a function of the combustor, operating variables. A small effect of radial fuel staging on reducing exhaust emissions (which were originally quite low) is demonstrated.

  3. Analytic vortex dynamics in an annular Bose-Einstein condensate

    Science.gov (United States)

    Toikka, L. A.; Suominen, K.-A.

    2016-05-01

    We consider analytically the dynamics of an arbitrary number and configuration of vortices in an annular Bose-Einstein condensate obtaining expressions for the free energy and vortex precession rates to logarithmic accuracy. We also obtain lower bounds for the lifetime of a single vortex in the annulus. Our results enable a closed-form analytic treatment of vortex-vortex interactions in the annulus that is exact in the incompressible limit. The incompressible hydrodynamics that is developed here paves the way for more general analytical treatments of vortex dynamics in non-simply-connected geometries.

  4. Electrorheological damper with annular ducts for seismic protection applications

    Science.gov (United States)

    Makris, Nicos; Burton, Scott A.; Taylor, Douglas P.

    1996-10-01

    This paper presents the design, analysis, testing and modeling of an electrorheological (ER) fluid damper developed for vibration and seismic protection of civil structures. The damper consists of a main cylinder and a piston rod that pushes an ER fluid through a stationary annular duct. The behavior of the damper can be approximated with Hagen - Poiseuille flow theory. The basic equations that describe the fluid flow across an annular duct are derived. Experimental results on the damper response with and without the presence of electric field are presented. As the rate of deformation increases, viscous stresses prevail over field-induced yield stresses and a smaller fraction of the total damper force can be controlled. Simple physically motivated phenomenological models are considered to approximate the damper response with and without the presence of electric field. Subsequently, the performance of a multilayer neural network constructed and trained by an efficient algorithm known as the Dependence Identification Algorithm is examined to predict the response of the electrorheological damper. A combination of a simple phenomenological model and a neural network is then proposed as a practical tool to approximate the nonlinear and velocity-dependent damper response.

  5. A compact annular ring microstrip antenna for WSN applications.

    Science.gov (United States)

    Wang, Daihua; Song, Linli; Zhou, Hanchang; Zhang, Zhijie

    2012-01-01

    A compact annular ring microstrip antenna was proposed for a wireless sensor network (WSN) application in the 2.4 GHz band. In this paper the major considerations of the conformal antenna design were the compact size and the impact on antenna's performance of a steel installation base. By using a chip resistor of large resistance (120 Ω) the antenna size was reduced to 38% of that a conventional annular ring patch antenna. With the addition of the steel installation base the resonant frequency of the antenna increases about 4.2% and the bandwidth reduces from 17.5% to 11.7% by adjusting the load resistance simultaneously. Several key parameters were discussed and optimized, and the antenna was fabricated and its performance measured. The antenna is well matched at 2.4 GHz with 34.2 dB return loss and -2.5 dBi peak gain. Meanwhile, it exhibits excellent radiation patterns with very low cross-polarization levels.

  6. A Compact Annular Ring Microstrip Antenna for WSN Applications

    Directory of Open Access Journals (Sweden)

    Daihua Wang

    2012-06-01

    Full Text Available A compact annular ring microstrip antenna was proposed for a wireless sensor network (WSN application in the 2.4 GHz band. In this paper the major considerations of the conformal antenna design were the compact size and the impact on antenna’s performance of a steel installation base. By using a chip resistor of large resistance (120 Ω the antenna size was reduced to 38% of that a conventional annular ring patch antenna. With the addition of the steel installation base the resonant frequency of the antenna increases about 4.2% and the bandwidth reduces from 17.5% to 11.7% by adjusting the load resistance simultaneously. Several key parameters were discussed and optimized, and the antenna was fabricated and its performance measured. The antenna is well matched at 2.4 GHz with 34.2 dB return loss and –2.5 dBi peak gain. Meanwhile, it exhibits excellent radiation patterns with very low cross-polarization levels.

  7. Annular bullous lesions with atypical erythema multiforme in leprosy.

    Science.gov (United States)

    Shah, Aishani; Mahajan, Rashmi; Ninama, Kishan; Bilimoria, Freny

    2014-09-01

    Erythema nodosum leprosum (ENL) is an immune complex-mediated reaction that may complicate the course of multibacillary leprosy. Bullous lesions in Type II reaction, though reported, are exceedingly rare. We report the case of a 32 year old female patient who presented initially at our OPD with erythema nodosum. Cutaneous examination revealed impaired sensation over dorsum of right foot and thickened right lateral popliteal nerve. Slit skin smear (SSS) from ear lobes revealed AFB with a bacteriological index of 2+. She was started on MDT, tablet ofloxacin 200 mg twice a day, and 30 mg oral prednisolone. Two months later, she presented with generalised pruritus, large target lesions over the back, and hemorrhagic bullae over lower extremities and annular pattern of bullae, over both arms. A SSS was repeated which was positive for AFB. Histopathology from bullous lesions was consistent with ENL. Direct Immunofluorescence (DIF) study was negative. Our patient improved rapidly after she was started on thalidomide 100 mg twice daily, with withdrawal of ofloxacin. Erythema Multiforme (EMF) and annular bullous lesions have been reported in patients on treatment with ofloxacin. This case is being presented due to the unusual and varied manifestation of Type II lepra reaction in a 34 year old female patient.

  8. Investigation of azimuthal staging concepts in annular gas turbines

    Science.gov (United States)

    Noiray, Nicolas; Bothien, Mirko; Schuermans, Bruno

    2011-10-01

    In this work, the influence of azimuthal staging concepts on the thermoacoustic behavior of annular combustion chambers is assessed theoretically and numerically. Staging is a well-known and effective method to abate thermoacoustic pulsations in combustion chambers. However, in the case of, for example, fuel staging the associated inhomogeneity of equivalence ratio may result in increased levels of NOx emissions. In order to minimize this unwanted effect a staging concept is required in which the transfer functions of the burners are changed while affecting the equivalence ratio as little as possible. In order to achieve this goal, a theoretical framework for predicting the influence of staging concepts on pulsations has been developed. Both linear and nonlinear analytical approaches are presented and it is shown that the dynamics of azimuthal modes can be described by coupled Van der Pol oscillators. A criterion based on the thermoacoustic coupling strength and on the asymmetry degree provides the modal behavior in the annular combustor, i.e. standing or traveling waves. The model predictions have been verified by numerical simulations of a heavy-duty gas turbine using an in-house thermoacoustic network-modeling tool. The interaction between the heat release of the flame and the acoustic field was modeled using measured transfer functions and source terms. These numerical simulations confirmed the original theoretical considerations.

  9. Portal annular pancreas: a systematic review of a clinical challenge.

    Science.gov (United States)

    Harnoss, Jonathan M; Harnoss, Julian C; Diener, Markus K; Contin, Pietro; Ulrich, Alexis B; Büchler, Markus W; Schmitz-Winnenthal, Friedrich H

    2014-10-01

    Portal annular pancreas (PAP) is an asymptomatic congenital pancreas anomaly, in which portal and/or mesenteric veins are encased by pancreas tissue. The aim of the study was to determine the role of PAP in pancreatic surgery as well as its management and potential complication, specifically, postoperative pancreatic fistula (POPF).On the basis of a case report, the MEDLINE and ISI Web of Science databases were systematically reviewed up to September 2012. All articles describing a case of PAP were considered.In summary, 21 studies with 59 cases were included. The overall prevalence of PAP was 2.4% and the patients' mean (SD) age was 55.9 (16.2) years. The POPF rate in patients with PAP (12 pancreaticoduodenectomies and 3 distal pancreatectomies) was 46.7% (in accordance with the definition of the International Study Group of Pancreatic Surgery).Portal annular pancreas is a quite unattended pancreatic variant with high prevalence and therefore still remains a clinical challenge to avoid postoperative complications. To decrease the risk for POPF, attentive preoperative diagnostics should also focus on PAP. In pancreaticoduodenectomy, a shift of the resection plane to the pancreas tail should be considered; in extensive pancreatectomy, coverage of the pancreatic remnant by the falciform ligament could be a treatment option.

  10. The Growth of Instabilities in Annular Liquid Sheets

    Energy Technology Data Exchange (ETDEWEB)

    Duke, Daniel J.; Honnery, Damon R; Soria, Julio

    2015-11-01

    An annular liquid sheet surrounded by parallel co-flowing gas is an effective atomiser. However, the initial instabilities which determine the primary break-up of the liquid sheet are not well understood. Lack of agreement on the influence of the boundary conditions and the non-dimension scaling of the initial instability persists between theoretical stability analyses and experiments. To address this matter, we have undertaken an experimental parametric study of an aerodynamically-driven, non-swirling annular water sheet. The effects of sheet thickness, inner and outer gas-liquid momentum ratio were investigated over an order of magnitude variation in Reynolds and Weber number. From high-speed image correlation measurements in the near-nozzle region, we propose new empirical correlations for the frequency of the instability as a function of the total gas-liquid momentum ratio, with good non-dimensional collapse. From analysis of the instability velocity probability densities, we find two persistent and distinct superimposed instabilities with different growth rates. The first is a short-lived, rapidly saturating sawtooth-like instability. The second is a slower-growing stochastic instability which persists through the break-up of the sheet. The presence of multiple instabilities whose growth rates do not strongly correlate with the shear velocities may explain some of the discrepancies between experiments and stability analyses.

  11. Non-null annular subaperture stitching interferometry for aspheric test

    Science.gov (United States)

    Zhang, Lei; Liu, Dong; Shi, Tu; Yang, Yongying; Chong, Shiyao; Miao, Liang; Huang, Wei; Shen, Yibing; Bai, Jian

    2015-10-01

    A non-null annular subaperture stitching interferometry (NASSI), combining the subaperture stitching idea and non-null test method, is proposed for steep aspheric testing. Compared with standard annular subaperture stitching interferometry (ASSI), a partial null lens (PNL) is employed as an alternative to the transmission sphere, to generate different aspherical wavefronts as the references. The coverage subaperture number would thus be reduced greatly for the better performance of aspherical wavefronts in matching the local slope of aspheric surfaces. Instead of various mathematical stitching algorithms, a simultaneous reverse optimizing reconstruction (SROR) method based on system modeling and ray tracing is proposed for full aperture figure error reconstruction. All the subaperture measurements are simulated simultaneously with a multi-configuration model in a ray-tracing program, including the interferometric system modeling and subaperture misalignments modeling. With the multi-configuration model, full aperture figure error would be extracted in form of Zernike polynomials from subapertures wavefront data by the SROR method. This method concurrently accomplishes subaperture retrace error and misalignment correction, requiring neither complex mathematical algorithms nor subaperture overlaps. A numerical simulation exhibits the comparison of the performance of the NASSI and standard ASSI, which demonstrates the high accuracy of the NASSI in testing steep aspheric. Experimental results of NASSI are shown to be in good agreement with that of Zygo® VerifireTM Asphere interferometer.

  12. Stem Cells

    OpenAIRE

    Madhukar Thakur

    2009-01-01

    Objective: The objective of this presentation is to create awareness of stem cell applications in the ISORBE community and to foster a strategy of how the ISORBE community can disseminate information and promote the use of radiolabeled stem cells in biomedical applications. Methods: The continued excitement in Stem Cells, in many branches of basic and applied biomedical science, stems from the remarkable ability of stem cells to divide and develop into different types of cells in ...

  13. Core-annular flow through a horizontal pipe: Hydrodynamic counterbalancing of buoyancy force on core

    NARCIS (Netherlands)

    Ooms, G.; Vuik, C.; Poesio, P.

    2007-01-01

    A theoretical investigation has been made of core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question of how the buoyancy force on the core, caused by a density difference betwe

  14. DC intrinsic Josephson effect in 1{mu}m-lateral-size annular Bi-2212 stacks

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S.J.; Yamashita, T. [Tohoku Univ., Sendai (Japan). Research Inst. of Electrical Comunication; Latyshev, Y.I.; Pavlenko, V.N. [Tohoku Univ., Sendai (Japan); Inst of Radio-Engineerig and Electronics Russian Academic of Sciences, Moscow (Russian Federation)

    1999-11-10

    Small annular junctions were the subjects of particular interest last decade because of possibility of flux trapping (see, e.g. [1]). Related magnetic field can contain radial component affecting Josephson critical current. Here we report on the first studies of intrinsic dc Josephson effect [2] in small annular type Bi-2212 mesas and its sensitivity to the trapped flux. (translated by NEDO)

  15. A magnetorheological valve with both annular and radial fluid flow resistance gaps

    International Nuclear Information System (INIS)

    In order to increase the efficiency of magnetorheological (MR) valves, Ai et al (2006) proposed an MR valve simultaneously possessing annular and radial fluid flow resistance channels with the assumption that the magnetic flux densities at the annular and radial fluid flow gaps are identical. In this paper, an MR valve simultaneously possessing annular and radial fluid flow resistance channels is designed, fabricated, modeled and tested. A model for the developed MR valve is produced and its performances are theoretically predicted based on the average magnetic flux densities in the annular and radial fluid flow gaps through finite element analysis. The theoretical results for the developed MR valve are compared with the experimental results. In addition, the performances of the developed MR valve are theoretically and experimentally compared with those of the MR valve with only annular fluid flow gaps. It has been shown that the theoretical results match well with the experimental results. Mainly attributed to the radial fluid flow gaps, the pressure drops across the MR valve with both annular and radial fluid flow gaps are larger than those across the MR valve with only annular fluid flow gaps for varying valve parameters. The radial fluid flow gaps in the MR valve can reach a higher efficiency and larger controllable range than those by annular fluid flow gaps to some extent

  16. Erythema annulare centrifugum as presenting sign of activation of breast cancer*

    Science.gov (United States)

    Topal, Ilteris Oguz; Topal, Yunus; Sargan, Aytul; Duman, Hatice; Gungor, Sule; Goncu, Ozgur Emek Kocaturk; Ozekinci, Selver

    2015-01-01

    Erythema annulare centrifugum is a figurate erythema of unknown etiology. It has been associated with many different entities, including infections, food allergy, drug reactions and malignant neoplasms. Herein, we report a case of erythema annulare centrifugum as presenting sign of activation of breastcancer. PMID:26734884

  17. Erythema annulare centrifugum as presenting sign of activation of breast cancer.

    Science.gov (United States)

    Topal, Ilteris Oguz; Topal, Yunus; Sargan, Aytul; Duman, Hatice; Gungor, Sule; Goncu, Ozgur Emek Kocaturk; Ozekinci, Selver

    2015-01-01

    Erythema annulare centrifugum is a figurate erythema of unknown etiology. It has been associated with many different entities, including infections, food allergy, drug reactions and malignant neoplasms. Herein, we report a case of erythema annulare centrifugum as presenting sign of activation of breastcancer.

  18. Entrance and exit region friction factor models for annular seal analysis. Ph.D. Thesis

    Science.gov (United States)

    Elrod, David Alan

    1988-01-01

    The Mach number definition and boundary conditions in Nelson's nominally-centered, annular gas seal analysis are revised. A method is described for determining the wall shear stress characteristics of an annular gas seal experimentally. Two friction factor models are developed for annular seal analysis; one model is based on flat-plate flow theory; the other uses empirical entrance and exit region friction factors. The friction factor predictions of the models are compared to experimental results. Each friction model is used in an annular gas seal analysis. The seal characteristics predicted by the two seal analyses are compared to experimental results and to the predictions of Nelson's analysis. The comparisons are for smooth-rotor seals with smooth and honeycomb stators. The comparisons show that the analysis which uses empirical entrance and exit region shear stress models predicts the static and stability characteristics of annular gas seals better than the other analyses. The analyses predict direct stiffness poorly.

  19. Annular core liquid-salt cooled reactor with multiple fuel and blanket zones

    Science.gov (United States)

    Peterson, Per F.

    2013-05-14

    A liquid fluoride salt cooled, high temperature reactor having a reactor vessel with a pebble-bed reactor core. The reactor core comprises a pebble injection inlet located at a bottom end of the reactor core and a pebble defueling outlet located at a top end of the reactor core, an inner reflector, outer reflector, and an annular pebble-bed region disposed in between the inner reflector and outer reflector. The annular pebble-bed region comprises an annular channel configured for receiving pebble fuel at the pebble injection inlet, the pebble fuel comprising a combination of seed and blanket pebbles having a density lower than the coolant such that the pebbles have positive buoyancy and migrate upward in said annular pebble-bed region toward the defueling outlet. The annular pebble-bed region comprises alternating radial layers of seed pebbles and blanket pebbles.

  20. Types of Stem Cells

    Science.gov (United States)

    ... PDF) Download an introduction to stem cells and stem cell research. Stem Cell Glossary Stem cell terms to know. ... stem cells blog from the International Society for Stem Cell Research. Learn About Stem Cells From Lab to You ...

  1. Design of an Annular Disc Subject to Thermomechanical Loading

    Directory of Open Access Journals (Sweden)

    Sergei Alexandrov

    2012-01-01

    Full Text Available Two solutions to design a thin annular disc of variable thickness subject to thermomechanical loading are proposed. It is assumed that the thickness of the disc is everywhere sufficiently small for the stresses to be averaged through the thickness. The state of stress is plane. The initiation of plastic yielding is controlled by Mises yield criterion. The design criterion for one of the solutions proposed requires that the distribution of stresses is uniform over the entire disc. In this case there is a relation between optimal values of the loading parameters at the final stage. The specific shape of the disc corresponds to each pair of such parameters. The other solution is obtained under the additional requirement that the distribution of strains is uniform. This solution exists for the disc of constant thickness at specific values of the loading parameters.

  2. Study of spiral flow generated through an annular slit

    Science.gov (United States)

    Kim, Tae Hun; Matsuo, Shigeru; Setoguchi, Toshiaki; Kim, Heuy-Dong

    2005-06-01

    The effect of pressurized air inlets in the reservoir upstream of the annular slit on characteristics of the axial and tangential velocity components is investigated numerically, and the mechanism of occurrence of spiral nozzle flow is clarified. In simulations, Unified Platform for Aerospace Computational Simulation (UPACS) is used. The governing equations under consideration are the unsteady compressible Navier - Stokes. A second-order finite volume scheme with MUSCL (Roe scheme) is used to discretize the spatial derivatives, and a second order-central difference scheme for the viscous terms, and a MFGS (Matrix Free Gauss Seidel) is employed for time integration. Spalart-Allmaras model was used as a turbulence model. The results obtained are compared with velocity distributions in the experiment measured by the two-component fiber optic laser Doppler velocimeter system. The existence of discrete pressurized air inlets that leads to the occurrence of asymmetrical characteristics is a very important factor for the formation of spiral flow.

  3. Study of Spiral Flow Generated through an Annular Slit

    Institute of Scientific and Technical Information of China (English)

    Tae Hun KIM; Shigeru MATSUO; Toshiaki SETOGUCHI; Heuy-Dong KIM

    2005-01-01

    @@ The effect of pressurized air inlets in the reservoir upstream of the annular slit on characteristics of the axial and tangential velocity components is investigated numerically, and the mechanism of occurrence of spiral nozzle flow is clarified. In simulations, Unified Platform for Aerospace Computational Simulation (UPACS) is used. The governing equations under consideration are the unsteady compressible Navier - Stokes. A second-order finite volume scheme with MUSCL (Roe scheme) is used to discretize the spatial derivatives, and a second order-central difference scheme for the viscous terms, and a MFGS (Matrix Free Gauss Seidel) is employed for time integration. Spalart-Allmaras model was used as a turbulence model. The results obtained are compared with velocity distributions in the experiment measured by the two-component fiber optic laser Doppler velocimeter system. The existence of discrete pressurized air inlets that leads to the occurrence of asymmetrical characteristics is a very important factor for the formation of spiral flow.

  4. Liquid transfer and entrainment correlation for droplet-annular flow

    International Nuclear Information System (INIS)

    A correlation for the amount of entrained liquid in annular flow has been developed from a simple model and experimental data. There are basically two different regions of entrainment, namely, the entrance and quasi-equilibrium regions. The correlation for the equilibrium region is expressed in terms of the dimensionless gas flux, diameter, cand total liquid Reynolds number. The entrance effect is taken into account by an exponential relaxation function. It has been shown that this new model can satisfactorily correlate wide ranges of experimental data for water. Furthermore, the necessary distance for the development of entrainment is identified. These correlations, therefore, can supply accurate information on entrainment which has not been available previously

  5. Development of annular targets for {sup 99}MO production.

    Energy Technology Data Exchange (ETDEWEB)

    Conner, C.; Lewandowski, E. F.; Snelgrove, J. L.; Liberatore, M. W.; Walker, D. E.; Wiencek, T. C.; McGann, D. J.; Hofman, G. L.; Vandegrift, G. F.

    1999-09-30

    The new annular target performed well during irradiation. The target is inexpensive and provides good heat transfer during irradiation. Based on these and previous tests, we conclude that targets with zirconium tubes and either nickel-plated or zinc-plated foils work well. We proved that we could use aluminum target tubes, which are much cheaper and easier to work with than the zirconium tubes. In aluminum target tubes nickel-plated fission-recoil barriers work well and prevent bonding of the foil to the new target tubes during irradiation. Also, zinc-plated and aluminum-foil barriers appear promising in anodized aluminum tubes. Additional tests are anticipated to address such issues as fission-recoil barrier thickness and uranium foil composition. Overall, however, the target was successful and will provide an inexpensive, efficient way to irradiate LEU metal foil for the production of {sup 99}Mo.

  6. Two-phase flow instabilities in a vertical annular channel

    Energy Technology Data Exchange (ETDEWEB)

    Babelli, I.; Nair, S.; Ishii, M. [Purdue Univ., West Lafayette, IN (United States)

    1995-09-01

    An experimental test facility was built to study two-phase flow instabilities in vertical annular channel with emphasis on downward flow under low pressure and low flow conditions. The specific geometry of the test section is similar to the fuel-target sub-channel of the Savannah River Site (SRS) Mark 22 fuel assembly. Critical Heat Flux (CHF) was observed following flow excursion and flow reversal in the test section. Density wave instability was not recorded in this series of experimental runs. The results of this experimental study show that flow excursion is the dominant instability mode under low flow, low pressure, and down flow conditions. The onset of instability data are plotted on the subcooling-Zuber (phase change) numbers stability plane.

  7. Mathematical model for multicomponent separations on the continuous annular chromatograph

    Energy Technology Data Exchange (ETDEWEB)

    Bratzler, R.L.; Begovich, J.M.

    1980-12-01

    A model for multicomponent separations on ion exchange columns has been adapted for use in studying the performance of the continuous annular chromatograph. The model accurately predicts solute peak positions in the column effluent and qualitatively predicts trends in solute effluent resolution as a function of increasing bandwidth of the solute feed pulse. The major virtues of the model are its simplicity in terms of the calculations involved and the fact that it incorporates the nonlinear solute-resin binding isotherms common in many ion exchange separations. Because dispersion effects are not accounted for in the model, discrepancies exist between the shapes of the effluent peaks predicted by the model and those determined experimentally.

  8. A Novel Design of Magnetorheological Damper with Annular Radial Channel

    Directory of Open Access Journals (Sweden)

    Shisha Zhu

    2016-01-01

    Full Text Available With the development of automotive vibration technology, the semiactive suspension system with adjustable damping force and high reliability is taken seriously. The magnetorheological damper (MRD that applies intelligent material (magnetorheological fluid is the key element of this system. It can achieve a continuous and adjustable damping and then reaches the purpose of comfort. In order to improve the damping effect of MRD, this paper presents a MRD, which has magnetorheological (MR effect along annular radial channel. The paper completely designs the structure and magnetic circuit of MRD. Based on the theory of electromagnetism and MR fluid dynamics, the paper analyzes and tests the external characteristics of the MRD by the MATLAB/Simulink and the vibration experiment. The results compared with ordinary MRD reveal that the damping force obviously increases and has wide adjustable range, thus verifying the reasonableness of the damper design.

  9. The Southern Annular Mode: a comparison of indices

    Directory of Open Access Journals (Sweden)

    M. Ho

    2011-08-01

    Full Text Available The Southern Annular Mode (SAM has been identified as a climate mechanism with potentially significant impacts on the Australian hydroclimate. However, despite the identification of some relationships between SAM and Australia's hydroclimate, the association has not been extensively explored or robustly quantified. Further complicating the situation is the existence of numerous indices (or methods by which SAM has been approximated. In this paper, the various SAM definitions and indices are reviewed and the similarities and discrepancies are discussed, along with the strengths and weaknesses of each index development approach. Further, the sensitivity of the relationship between SAM and Australian rainfall on choice of SAM index is quantified and recommendations are given as to the most appropriate index to use when assessing the impacts of the SAM on Australia's hydroclimate.

  10. Damping of cylindrical structures subject to annular flow

    International Nuclear Information System (INIS)

    In previous reports theoretical methods have been described for estimating the aerodynamic forces acting on cylinders vibrating laterally when surrounded by an annulus carrying high velocity gas. For a certain restricted set of geometries it is possible to predict whether a particular structure is stable or unstable and to determine the level of aerodynamic damping positive or negative due to the presence of the gas. This report describes experimental work which validates the computer program in which the theoretical methods are embodied; in particular the damping, inertial and decentralising forces acting on a cylinder in an annulus are measured and compared with theory over a range of frequencies from 0 to 25 Hz, and of Reynolds numbers from zero to 104. In addition a summary of simple relationships is provided which can be used to provide credible initial estimates of both the positive and negative damping of cylinders in a range of annular geometries. (author)

  11. Fluxons in long and annular intrinsic Josephson junction stacks

    Science.gov (United States)

    Clauss, T.; Oehmichen, V.; Mößle, M.; Müller, A.; Weber, A.; Koelle, D.; Kleiner, R.

    2002-12-01

    A promising approach towards a THz oscillator based on intrinsic Josephson junctions in high-temperature superconductors is based on the collective motion of Josephson fluxons, which are predicted to form various configurations ranging from a triangular to a quadratic lattice. Not only for this reason, but certainly also for the sake of basic physics, several experimental and theoretical investigations have been done on the subject of collective fluxon dynamics in stacked intrinsic Josephson junctions. In this paper we will present some experimental results on the fluxon dynamics of long intrinsic Josephson junction stacks made of Bi2Sr2CaCu2O8. The stacks were formed either in an open or in an annular geometry, and clear resonant fluxon modes were observed. Experiments discussed include measurements of current-voltage characteristics in external magnetic fields and in external microwave fields.

  12. Aerodynamic performance of an annular classical airfoil cascade

    Science.gov (United States)

    Bergsten, D. E.; Stauter, R. C.; Fleeter, S.

    1983-01-01

    Results are presented for a series of experiments that were performed in a large-scale subsonic annular cascade facility that was specifically designed to provide three-dimensional aerodynamic data for the verification of numerical-calculation codes. In particular, the detailed three-dimensional aerodynamic performance of a classical flat-plate airfoil cascade is determined for angles of incidence of 0, 5, and 10 deg. The resulting data are analyzed and are correlated with predictions obtained from NASA's MERIDL and TSONIC numerical programs. It is found that: (1) at 0 and 5 deg, the airfoil surface data show a good correlation with the predictions; (2) at 10 deg, the data are in fair agreement with the numerical predictions; and (3) the two-dimensional Gaussian similarity relationship is appropriate for the wake velocity profiles in the mid-span region of the airfoil.

  13. Investigation of a low NOx full-scale annular combustor

    Science.gov (United States)

    1982-01-01

    An atmospheric test program was conducted to evaluate a low NOx annular combustor concept suitable for a supersonic, high-altitude aircraft application. The lean premixed combustor, known as the vortex air blast (VAB) concept, was tested as a 22.0-cm diameter model in the early development phases to arrive at basic design and performance criteria. Final demonstration testing was carried out on a full scale combustor of 0.66-m diameter. Variable geometry dilution ports were incorporated to allow operation of the combustor across the range of conditions between idle (T(in) = 422 K, T(out) = 917 K) and cruise (T(in) = 833 K, T(out) - 1778 K). Test results show that the design could meet the program NOx goal of 1.0 g NO2/kg fuel at a one-atmospheric simulated cruise condition.

  14. Intermittent Flow of Granular Matter in an Annular Geometry

    Science.gov (United States)

    Brzinski, Ted; Daniels, Karen E.

    Granular solids can be subjected to a finite stress below which the response is elastic. Above this yield stress, however, the material fails catastrophically, undergoing a rapid plastic deformation. In the case of a monotonically increasing stress the material exhibits a characteristic stick-slip response. We investigate the statistics of this intermittent failure in an annular shear geometry, driven with a linear-ramp torque in order to generate the stick-slip behavior. The apparatus is designed to allow visual access to particle trajectories and inter-particle forces (through the use of photoelastic materials). Additionally, twelve piezoelectric sensors at the outer wall measure acoustic emissions due to the plastic deformation of the material. We vary volume fraction, and use both fixed and deformable boundaries. We measure how the distribution of slip size and duration are related to the bulk properties of the packing, and compare to systems with similar governing statistics.

  15. Mathematical model for multicomponent separations on the continuous annular chromatograph

    International Nuclear Information System (INIS)

    A model for multicomponent separations on ion exchange columns has been adapted for use in studying the performance of the continuous annular chromatograph. The model accurately predicts solute peak positions in the column effluent and qualitatively predicts trends in solute effluent resolution as a function of increasing bandwidth of the solute feed pulse. The major virtues of the model are its simplicity in terms of the calculations involved and the fact that it incorporates the nonlinear solute-resin binding isotherms common in many ion exchange separations. Because dispersion effects are not accounted for in the model, discrepancies exist between the shapes of the effluent peaks predicted by the model and those determined experimentally

  16. Annular elastolytic giant cell granuloma of conjunctiva: A case report

    Directory of Open Access Journals (Sweden)

    Karabi Konar

    2014-01-01

    Full Text Available Annular elastolytic giant cell granuloma is a condition characterized histologically by damaged elastic fibers associated with preponderance of giant cells along with absence of necrobiosis, lipid, mucin, and pallisading granuloma. It usually occurs on sun-damaged skin and hence the previous name actinic granuloma. A similar process occurs on the conjunctiva. Over the past three decades only four cases of conjunctival actinic granuloma have been documented. All the previous patients were females with lesions in nasal or temporal bulbar conjunctiva varying 2-3 mm in size. We report a male patient aged 70 years presenting with a 14 mm × 7 mm fleshy mass on right lower bulbar conjunctiva. Clinical differential diagnoses were lymphoma, squamous cell carcinoma in situ and amyloidosis. Surgical excision followed by histopathology confirmed it to be a case of actinic granuloma. This is the first case of isolated conjunctival actinic granuloma of such a large size reported from India.

  17. Periocular granuloma annulare: a case report and review of literature.

    Science.gov (United States)

    Chiang, Katherine; Bhalla, Rohan; Mesinkovska, Natasha A; Piliang, Melissa P; Tamburro, Joan E

    2014-01-01

    Granuloma annulare (GA) is a granulomatous dermatosis that rarely presents on the face and is extremely uncommon in the periocular region. We report our experience with the presentation and management of GA lesions on the eyelids of a 17-year-old girl. We performed a review of published literature and identified 13 cases of pediatric periocular GA. One additional case was identified upon review of all pediatric GA cases at the Cleveland Clinic Foundation. Review of these cases suggests that periocular GA is a benign condition that spontaneously regresses within a few months. GA nodules have a predilection for the upper eyelids. A greater incidence is noted in African American children. Awareness of the self-resolving nature of this condition can prevent unnecessary surgical excisions in affected children. PMID:23551387

  18. Performance of annular flow sterilizer irradiated by a germicidal lamp

    Energy Technology Data Exchange (ETDEWEB)

    Sugawara, T.; Yoneya, M.; Ohashi, H. (Akita Univ. (Japan))

    1981-10-01

    Theoretical and experimental studies were conducted on the UV-inactivation characteristics of Bacillus subtilis spores in an annular-flow sterilizer irradiated by a germicidal lamp located at the center of the inner tube. Experimental results for sterilizer performance in laminar spore-suspension flow were well simulated dynamically and statically by theoretical considerations which incorporated multi-targets with single-hit model for the UV-inactivation kinetic and the diffuse light model for the angle characteristic of lamp, along with due attention to the parabolic velocity distribution and the negligible diffusion of spores. Scale on the outside wall of the inner tube was checked by the use of a cylindrical chemical actinometer. Calculated examples elucidate the reason why careful inspection is needed of UV-inactivation kinetics, angle characteristics of lamp, and fluid mixing to evaluate performance of actual flow UV sterilizers at high extent of inactivation up to the order of 99.999%.

  19. Magnetically guided free surface annular NaK flow experiment

    International Nuclear Information System (INIS)

    In order to gain basic information on the magnetically guided liquid metal Li waterfall type blanket concept for ICF reactors and liquid metal Li free surface flow for FMIT type accelerator target, an experimental study was conducted by using LINAK (NaK: 50 l, Ar: 0-0.3 MPa) device. A 45 mm O.D. and 25 mm I.D. annular free jet of NaK, which flowed downwards coaxially through a superconducting magnet (2.7 Tmax, B=0.38 T at the nozzle exit), was formed in vacuum chamber and at the nozzle exit where magnetic flux density B was divergent. The experiment covered ranges of U=0.5-2.5 m/s and B=0-0.38 T at the nozzle exit. Photographic and VTR observations were made on the behavior of outer surface of annular flow. The results are summarized as follows. (1) When B=0 T, the downward flow was rather convergent due to the surface tension. (2) By applying B, the flow became divergent like a cone shell and more stable. The divergent half angle increased with intensifying B. (3) The experimental results on the flow divergence agreed fairly well with the numerical analysis which took into account the MHD force, the surface tension and the gravitational force. (4) No growth of outer surface disturbance occurred within an attained maximum divergent half angle of 8deg or less. The results are considered to be encouraging for applying to ICF blanket and FMIT type target. (author)

  20. Stem system

    Directory of Open Access Journals (Sweden)

    Shajmardanova L.R.

    2008-01-01

    Full Text Available The article shows the stem cells from the point of view of systemic anatomy, where they are united into an entire stem system. This integration shows various advantages for better understanding the stem cells role in the body. Authors, considering functions and action mechanism of stem cells, phylogeny, ontogeny, regulation of functions, explain the base for stem cells system existance. The definition and terminology, age peculiarities, relationship with other systems of organs and differences are offered. The theoretical proof of primary-integrative role of stem system is provided for all other systems in body. Of particular importance is the role of stem system as a link between neural and endocrine systems. The work helps to sistematize data on investigations of stem cells, their entire-system perception, that will ease the goals determining for further research and their clinical use.

  1. Numerical Simulation of the Laval Annular Mechanical Foam Breaker for Foam Drilling

    Directory of Open Access Journals (Sweden)

    Pin Lu Cao

    2013-12-01

    Full Text Available The Computational Fluid Dynamics (CFD code, Fluent, is employed to simulate the flow phenomena inside the annular foam breaker in order to improve its performance. The numerical simulation results show that the value and the distribution of the negative pressure are very important for the annular foam breaker. The design of the Laval nozzle not only can increase the fluid velocity, but also can reduce the pressure value from -30.2 to -50.3 kPa compared with the common annular nozzle foam breaker. In order to improve the range of the internal negative pressure, the two-stage Laval annular foam breaker is designed in this study. The analysis results show the distance between the two annular slit have greatly influence on its performance. There is a small overlap area between the two negative pressure zones generated by the two annular slits. The smaller the value distance is, the larger the overlap zone is. When the value of the distance decreases to 50 mm, the minimum negative pressure can be reduced to approximately -65.5 kPa. Meanwhile, the range of the internal negative pressure is larger than the single Laval annular foam breaker, which is benefit to break foam.

  2. On the Motion of an Annular Film in Microgravity Gas-Liquid Flow

    Science.gov (United States)

    McQuillen, John B.

    2002-01-01

    Three flow regimes have been identified for gas-liquid flow in a microgravity environment: Bubble, Slug, and Annular. For the slug and annular flow regimes, the behavior observed in vertical upflow in normal gravity is similar to microgravity flow with a thin, symmetrical annular film wetting the tube wall. However, the motion and behavior of this film is significantly different between the normal and low gravity cases. Specifically, the liquid film will slow and come to a stop during low frequency wave motion or slugging. In normal gravity vertical upflow, the film has been observed to slow, stop, and actually reverse direction until it meets the next slug or wave.

  3. Characterization of annular two-phase gas-liquid flows in microgravity

    Science.gov (United States)

    Bousman, W. Scott; Mcquillen, John B.

    1994-01-01

    A series of two-phase gas-liquid flow experiments were developed to study annular flows in microgravity using the NASA Lewis Learjet. A test section was built to measure the liquid film thickness around the perimeter of the tube permitting the three dimensional nature of the gas-liquid interface to be observed. A second test section was used to measure the film thickness, pressure drop and wall shear stress in annular microgravity two-phase flows. Three liquids were studied to determine the effects of liquid viscosity and surface tension. The result of this study provide insight into the wave characteristics, pressure drop and droplet entrainment in microgravity annular flows.

  4. Burnout in the boiling of water and freon-113 on tubes with annular fins

    International Nuclear Information System (INIS)

    This paper presents the results of numerical calculations of burnout heat flux associated with the boiling of Freon-113 and water on an annular fin of constant thickness which have been approximated by simple analytical relations. These are used to calculate the critical burnout parameters of tubes with an annular fin assembly. The calculated data may be used for the analysis of tubes with an annular fin assembly over a wide range of variation of the thermophysical properties of the material and geometrical parameters of the fin assembly

  5. Lattice resolution STEM

    International Nuclear Information System (INIS)

    dynamic form factors is explicitly included in these terms, which depend on interaction sites within the lattice. These effects are important in considering to what extent an atomic column by column analysis is feasible in STEM. This model thus provides a complete framework for STEM contrast under dynamical diffraction conditions for any bright field or annular electron detector, as well as for contrast from atomic ionization as recorded by EELS or X-ray emissions. Copyright (2002) Australian Society for Electron Microscopy Inc

  6. Construction of x-ray dark-field imaging with a view size of 80 mm square and first visualization of human articular cartilage of femoral head under a nearly clinical condition

    International Nuclear Information System (INIS)

    Field size of 80 mm x 80 mm for X-ray dark-field (DFI) imaging at 35 keV using a 2.16-mm-thick 440 Laue diffraction analyzer has been achieved. Under this condition, only refracted X-rays from sample can transmit through this filter to form DFI while the beam that has not changed its direction is repelled to the diffraction direction. Its spatial resolution is 10 microns or better. An excised human femoral head in a water-filled vinyl bag simulating a clinical condition shows a high-contrast and high-spatial-resolution articular cartilage that has not been visualized by X-ray technique. (author)

  7. Design of radial phononic crystal using annular soft material with low-frequency resonant elastic structures

    Science.gov (United States)

    Gao, Nansha; Wu, Jiu Hui; Yu, Lie; Xin, Hang

    2016-10-01

    Using FEM, we theoretically study the vibration properties of radial phononic crystal (RPC) with annular soft material. The band structures, transmission spectra, and displacement fields of eigenmode are given to estimate the starting and cut-off frequency of band gaps. Numerical calculation results show that RPC with annular soft material can yield low-frequency band gaps below 350 Hz. Annular soft material decreases equivalent stiffness of the whole structure effectively, and makes corresponding band gaps move to the lower frequency range. Physical mechanism behind band gaps is the coupling effect between long or traveling wave in plate matrix and the vibrations of corrugations. By changing geometrical dimensions of plate thickness e, the length of silicone rubber h2, and the corrugation width b, we can control the location and width of the first band gap. These research conclusions of RPC structure with annular soft material can potentially be applied to optimize band gaps, generate filters, and design acoustic devices.

  8. Entropy Analysis for Non-Newtonian Fluid Flow in Annular Pipe: Constant Viscosity Case

    Directory of Open Access Journals (Sweden)

    Mehmet Pakdemirli

    2004-06-01

    Full Text Available Abstract: In the present study, non-Newtonian flow in annular pipe is considered. The analytical solution for velocity and temperature fields is presented while entropy generation due to fluid friction and heat transfer is formulated. The third grade fluid with constant properties is accommodated in the analysis. It is found that reducing non-Newtonian parameter increases maximum velocity magnitude and maximum temperature in the annular pipe. Total entropy generation number attains high values in the region close to the inner wall of the annular pipe, which becomes significant for low non-Newtonian parameters. Increasing Brinkman number enhances entropy generation number, particularly in the region close to the annular pipe inner wall.

  9. Biofilm Community Dynamics in Bench-Scale Annular Reactors Simulating Arrestment of Chloraminated Drinking Water Nitrification

    Science.gov (United States)

    Annular reactors (ARs) were used to study biofilm community succession and provide an ecological insight during nitrification arrestment through simultaneously increasing monochloramine (NH2Cl) and chlorine to nitrogen mass ratios, resulting in four operational periods (I to IV)....

  10. Ultra-Wide-Band Microstrip Concentric Annular Ring Antenna for Wireless Communications

    Directory of Open Access Journals (Sweden)

    Salima Azzaz-Rahmani

    2012-01-01

    Full Text Available In this paper, a new design technique for bandwidth enhancement of concentric microstrip annular ring slot antennas is presented. Using this technique, an Ultra-Wide-Band antenna is designed with simulated bandwidth of 111.29%.

  11. Maximizing prosthetic valve size with the Top Hat supra-annular aortic valve

    DEFF Research Database (Denmark)

    Aagaard, Jan; Geha, Alexander S.

    2007-01-01

    BACKGROUND AND AIM OF THE STUDY: The CarboMedics Top Hat supra-annular aortic valve allows a one-size (and often two-size) increase over the standard intra-annular valve. This advantage should minimize the risk of patient-prosthesis mismatch, where the effective prosthetic valve orifice area...... is less than that of a normal valve. It is suggested that the ability to implant Top Hat valves having greater size, relative to standard intra-annular valves, may currently be under-utilized. Further, there has been some concern that Top Hat implantation can cause obstruction of the coronary ostia....... This study evaluates the authors' clinical experience with Top Hat supra-annular aortic valve size selection, and the technical aspects of implantation. METHODS: Between January 1999 and October 2005, a total of 251 consecutive patients underwent 252 aortic valve replacements with Top Hat supra...

  12. An iterative method for the solution of nonlinear systems using the Faber polynomials for annular sectors

    Energy Technology Data Exchange (ETDEWEB)

    Myers, N.J. [Univ. of Durham (United Kingdom)

    1994-12-31

    The author gives a hybrid method for the iterative solution of linear systems of equations Ax = b, where the matrix (A) is nonsingular, sparse and nonsymmetric. As in a method developed by Starke and Varga the method begins with a number of steps of the Arnoldi method to produce some information on the location of the spectrum of A. This method then switches to an iterative method based on the Faber polynomials for an annular sector placed around these eigenvalue estimates. The Faber polynomials for an annular sector are used because, firstly an annular sector can easily be placed around any eigenvalue estimates bounded away from zero, and secondly the Faber polynomials are known analytically for an annular sector. Finally the author gives three numerical examples, two of which allow comparison with Starke and Varga`s results. The third is an example of a matrix for which many iterative methods would fall, but this method converges.

  13. Stem Cells

    Directory of Open Access Journals (Sweden)

    Madhukar Thakur

    2015-02-01

    Full Text Available Objective: The objective of this presentation is to create awareness of stem cell applications in the ISORBE community and to foster a strategy of how the ISORBE community can disseminate information and promote the use of radiolabeled stem cells in biomedical applications. Methods: The continued excitement in Stem Cells, in many branches of basic and applied biomedical science, stems from the remarkable ability of stem cells to divide and develop into different types of cells in the body. Often called as Magic Seeds, stem cells are produced in bone marrow and circulate in blood, albeit at a relatively low concentration. These virtues together with the ability of stem cells to grow in tissue culture have paved the way for their applications to generate new and healthy tissues and to replace diseased or injured human organs. Although possibilities of stem cell applications are many, much remains yet to be understood of these remarkable magic seeds. Conclusion: This presentation shall briefly cover the origin of stem cells, the pros and cons of their growth and division, their potential application, and shall outline some examples of the contributions of radiolabeled stem cells, in this rapidly growing branch of biomedical science

  14. A research on the mechanisms of transition from annular flow in two-phase pipeline flow

    International Nuclear Information System (INIS)

    Various kinds mechanisms of transitions from two-phase annular flow in tubes were studied and modelled, and the affection factors on the transitions were also discussed. Some mathematical equations and transition criteria for every mechanisms presented were derived, and an unified general criterion for the annular flow transitions in whole range of pipe inclinations was recommended. The boundaries predicted show good agreement with the air-water two-phase experimental data

  15. Asymmetric Vibration of Polar Orthotropic Annular Circular Plates of Quadratically Varying Thickness with Same Boundary Conditions

    OpenAIRE

    Bhardwaj, N; Gupta, A. P.; Choong, K.K.

    2008-01-01

    In the present paper, asymmetric vibration of polar orthotropic annular circular plates of quadratically varying thickness resting on Winkler elastic foundation is studied by using boundary characteristic orthonormal polynomials in Rayleigh-Ritz method. Convergence of the results is tested and comparison is made with results already available in the existing literature. Numerical results for the first ten frequencies for various values of parameters describing width of annular plate, thicknes...

  16. Large Eddy Simulation of ignition in an annular multi-injector combustor

    Science.gov (United States)

    Vicquelin, Ronan; Philip, Maxime; Boileau, Matthieu; Schmitt, Thomas; Bourgoin, Jean-François; Durox, Daniel; Candel, Sébastien

    2013-11-01

    The present work deals with validating the LES methodology for transient ignition simulations, and in particular elucidating the mechanisms that control the light round sequence in a laboratory annular combustor, representative of many practical industrial systems. The simulation benefits from the unique experimental database built at EM2C on a fully transparent annular chamber equipped with 16 premixed swirled injectors. The F-TACLES combustion model is used for its ability to properly represent the flame propagation.

  17. A simple analytical model to study and control azimuthal instabilities in annular combustion chambers

    OpenAIRE

    Parmentier, Jean-François; Salas, Pablo; Wolf, Pierre; Staffelbach, Gabriel; Nicoud, Franck; Poinsot, Thierry

    2012-01-01

    This study describes a simple analytical method to compute the azimuthal modes appearing in annular combustion chambers and help analyzing experimental, acoustic and large eddy simulation (LES) data obtained in these combustion chambers. It is based on a one-dimensional zero Mach number formulation where N burners are connected to a single annular chamber. A manipulation of the corresponding acoustic equations in this configuration leads to a simple dispersion relation which can be solved by ...

  18. The numerical solution of flow field of short-annular combustion chamber

    Science.gov (United States)

    Xu, H.; Ning, H.

    1986-05-01

    The recirculating flow field of a short-annular combustion chamber has been studied. The body-fitting coordinate system and the 'simple' method combined with a constant viscosity model have been employed to solve the Navier-Stokes equations in a regime containing a complicated curved boundary. The result could provide the theoretical reference for the design and improvement of short-annular combustion chambers.

  19. Non-approximate method for designing annular field of two-mirror concentric system

    Institute of Scientific and Technical Information of China (English)

    Yuanshen Huang; Dongyue Zhu; Baicheng Li; Dawei Zhang; Zhengji Ni; Songlin Zhuang

    2012-01-01

    Annular field aberrations of a three-reflection concentric system, which are composed of two spherical mirrors, are analyzed. An annular field with a high level of aberration correction exists near the position where the principal ray is perpendicular to the object-image plane. Aberrations are determined by the object height and aperture angle. In this letter, the general expression of the system aberration is derived using the geometric method, and the non-approximate design method is proposed to calculate the radii of the annular fields that have minimum aberrations under different aperture angles. The closer to 0.5 (the ratio of the radius of convex mirror to the radius of concave mirror) is, the smaller the system aberration is. The examples analyzed by LABVIEW indicate that the annular field designed by the proposed method has the smallest aberration in a given system.%Annular field aberrations of a three-reflection concentric system,which are composed of two spherical mirrors,are analyzed.An annular field with a high level of aberration correction exists near the position where the principal ray is perpendicular to the object-image plane.Aberrations are determined by the object height and aperture angle.In this letter,the general expression of the system aberration is derived using the geometric method,and the non-approximate design method is proposed to calculate the radii of the annular fields that have minimum aberrations under different aperture angles.The closer to 0.5 (the ratio of the radius of convex mirror to the radius of concave mirror) is,the smaller the system aberration is.The examples analyzed by LABVIEW indicate that the annular field designed by the proposed method has the smallest aberration in a given system.

  20. Fabrication of Annular Pellet for HANARO Irradiation Test of Dual Cooled Fuel

    International Nuclear Information System (INIS)

    One of the most important components in a Pressurized Water Reactor affecting its safety and economy is a nuclear fuel. The traditional PWR fuel pellet has a shape of cylindrical tablets of about 8 mm in diameter with a chamfer and dishes. A significant reduction in its failure rate has resulted from the improvements in the fuel and cladding quality. Enhanced fuel assembly design allowed appreciable power density increases. However, it is difficult to achieve a significant increase of a power density under the current fuel pin design. An internally and externally cooled annular fuel has been considered seriously as a promising solution for an extended power uprate of a PWR fuel assembly. A dual cooled annular fuel shows a lot of advantages from the point of a fuel safety and its economy due to its unique configurational merit such as an increased heat transfer area and a thin pellet thickness. There must be a lot of considerations in the various fields to introduce an annular internally and externally cooled fuel to commercial PWR reactors. The dimensional changes of the annular fuel pellets during the early irradiation stage are very important, because they have an influence on the size of the gap between the pellet and the inner/outer claddings. In order to gain an insight to how the annular pellets deform, a HANARO irradiation test is planned for annular pellets with 5 different types. The detailed specification of the annular pellet was shown in Table 1. It is noted that Type C has the same pore structure as a commercial PWR pellet. The purpose of this paper is to report on the manufacturing process of an annular fuel pellet for a HANARO irradiation test

  1. An X-band high-impedance relativistic klystron amplifier with an annular explosive cathode

    Science.gov (United States)

    Zhu, Danni; Zhang, Jun; Zhong, Huihuang; Qi, Zumin

    2015-11-01

    The feasibility of employing an annular beam instead of a solid one in the X-band high-impedance relativistic klystron amplifier (RKA) is investigated in theory and simulation. Small-signal theory analysis indicates that the optimum bunching distance, fundamental current modulation depth, beam-coupling coefficient, and beam-loaded quality factor of annular beams are all larger than the corresponding parameters of solid beams at the same beam voltage and current. An annular beam RKA and a solid beam RKA with almost the same geometric parameters are compared in particle-in-cell simulation. Output microwave power of 100 MW, gain of 50 dB, and power conversion efficiency of 42% are obtained in an annular beam RKA. The annular beam needs a 15% lower uniform guiding magnetic field than the solid beam. Our investigations demonstrate that we are able to use a simple annular explosive cathode immersed in a lower uniform magnetic field instead of a solid thermionic cathode in a complicated partially shielding magnetic field for designing high-impedance RKA, which avoids high temperature requirement, complicated electron-optical system, large area convergence, high current density, and emission uniformity for the solid beam. An equivalent method for the annular beam and the solid beam on bunching features is proposed and agrees with the simulation. The annular beam has the primary advantages over the solid beam that it can employ the immersing uniform magnetic field avoiding the complicated shielding magnetic field system and needs a lower optimum guiding field due to the smaller space charge effect.

  2. Experimental verification of the flow characteristics of an active controlled microfluidic valve with annular boundary

    Science.gov (United States)

    Pan, Chun-Peng; Wang, Dai-Hua

    2014-03-01

    The principle and structural configuration of an active controlled microfluidic valve with annular boundary is presented in this paper. The active controlled flowrate model of the active controlled microfluidic valve with annular boundary is established. The prototypes of the active controlled microfluidic valves with annular boundaries with three different combinations of the inner and outer radii are fabricated and tested on the established experimental setup. The experimental results show that: (1) The active controlled microfluidic valve with annular boundary possesses the on/off switching and the continuous control capability of the fluid with simple structure and easy fabrication processing; (2) When the inner and outer diameters of the annular boundary are 1.5 mm and 3.5 mm, respectively, the maximum flowrate of the valve is 0.14 ml/s when the differential pressure of the inlet and outlet of the valve is 1000 Pa and the voltage applied to circular piezoelectric unimorph actuator is 100 V; (3) The established active controlled flowrate model can accurately predict the controlled flowrate of the active controlled microfluidic valves with the maximum relative error of 6.7%. The results presented in this paper lay the foundation for designing and developing the active controlled microfluidic valves with annular boundary driven by circular piezoelectric unimorph actuators.

  3. Design and characterization of the annular cathode high current pulsed electron beam source for circular components

    Science.gov (United States)

    Jiang, Wei; Wang, Langping; Wang, Xiaofeng

    2016-08-01

    In order to irradiate circular components with high current pulsed electron beam (HCPEB), an annular cathode based on carbon fiber bunches was designed and fabricated. Using an acceleration voltage of 25 kV, the maximum pulsed irradiation current and energy of this annular cathode can reach 7.9 kA and 300 J, respectively. The irradiation current density distribution of the annular cathode HCPEB source measured along the circumferential direction shows that the annular cathode has good emission uniformity. In addition, four 9310 steel substrates fixed uniformly along the circumferential direction of a metal ring substrate were irradiated by this annular cathode HCPEB source. The surface and cross-section morphologies of the irradiated samples were characterized by scanning electron microscopy (SEM). SEM images of the surface reveal that crater and surface undulation have been formed, which hints that the irradiation energy of the HCPEB process is large enough for surface modification of 9310 steel. Meanwhile, SEM cross-section images exhibit that remelted layers with a thickness of about 5.4 μm have been obtained in all samples, which proves that a good practical irradiation uniformity can be achieved by this annular cathode HCPEB source.

  4. Monthly rifampicin, ofloxacin, and minocycline therapy for generalized and localized granuloma annulare

    Directory of Open Access Journals (Sweden)

    Shilpa Garg

    2015-01-01

    Full Text Available Background: The localized form of granuloma annulare is usually self-limiting, resolving within 2 years. Generalized granuloma annulare, on the other hand, runs a protracted course, with spontaneous resolution being rare. It is also characterized by a later age of onset, an increased incidence of diabetes mellitus, poor response to therapy, and an increased prevalence of HLA Bw35. Objective: To assess the efficacy of monthly pulsed rifampicin, ofloxacin, and minocycline (ROM therapy in the management of granuloma annulare. Methods : Six biopsy proven patients of granuloma annulare were included in the study, five of the generalized variety, and one localized. Three of these patients were resistant to standard modalities of treatment. All six patients were treated with pulses of once monthly ROM till complete resolution of all lesions. Results were analyzed in terms of complete resolution of lesions and side effects. Presence of comorbid conditions was noted. Result: All six patients were successfully treated with 4-8 pulses of monthly ROM. None of the patients reported any adverse effects. Limitations: Small sample size and the lack of a control group are limitations. Conclusion: Treatment with pulses of once monthly ROM caused complete resolution of lesions in both localized and generalized granuloma annulare, even in cases recalcitrant to conventional therapy. There were no side effects in any of the patients. Larger trials are needed to substantiate the efficacy of monthly ROM in granuloma annulare.

  5. Absolute photonic band gap in 2D honeycomb annular photonic crystals

    International Nuclear Information System (INIS)

    Highlights: • A two-dimensional honeycomb annular photonic crystal (PC) is proposed. • The absolute photonic band gap (PBG) is studied. • Annular PCs show larger PBGs than usual air-hole PCs for high refractive index. • Annular PCs with anisotropic rods show large PBGs for low refractive index. • There exist optimal parameters to open largest band gaps. - Abstract: Using the plane wave expansion method, we investigate the effects of structural parameters on absolute photonic band gap (PBG) in two-dimensional honeycomb annular photonic crystals (PCs). The results reveal that the annular PCs possess absolute PBGs that are larger than those of the conventional air-hole PCs only when the refractive index of the material from which the PC is made is equal to 4.5 or larger. If the refractive index is smaller than 4.5, utilization of anisotropic inner rods in honeycomb annular PCs can lead to the formation of larger PBGs. The optimal structural parameters that yield the largest absolute PBGs are obtained

  6. Depth-targeted transvascular drug delivery by using annular-shaped photomechanical waves

    Science.gov (United States)

    Akiyama, Takuya; Sato, Shunichi; Ashida, Hiroshi; Terakawa, Mitsuhiro

    2011-02-01

    Laser-based drug delivery is attractive for the targeting capability due to high spatial controllability of laser energy. Recently, we found that photomechanical waves (PMWs) can transiently increase the permeability of blood vessels in skin, muscle and brain of rats. In this study, we examined the use of annular-shaped PMWs to increase pressure at target depths due to superposition effect of pressure waves. This can increase the permeability of blood vessels located in the specific depth regions, enabling depth-targeted transvascular drug delivery. Annular PMWs were produced by irradiating a laser-absorbing material with annular-shaped pulsed laser beams that were produced by using an axicon lens. We first examined propagation and pressure characteristics of annular PMWs in tissue phantoms and confirmed an increased pressure at a target depth, which can be controlled by changing laser parameters. We injected Evans blue (EB) into a rat tail vein, and annular PMWs (inner diameter, 3 mm; outer diameter, 5 mm) were applied from the myofascial surface of the anterior tibialis muscle. After perfusion fixation, we observed fluorescence originating from EB in the tissue. We observed intense fluorescence at a target depth region of around 5 mm. These results demonstrate the capability of annular PMWs for depth-targeted transvascular drug delivery.

  7. Fluid-Structure Interaction Analysis on Turbulent Annular Seals of Centrifugal Pumps during Transient Process

    Directory of Open Access Journals (Sweden)

    Qinglei Jiang

    2011-01-01

    Full Text Available The current paper studies the influence of annular seal flow on the transient response of centrifugal pump rotors during the start-up period. A single rotor system and three states of annular seal flow were modeled. These models were solved using numerical integration and finite difference methods. A fluid-structure interaction method was developed. In each time step one of the three annular seal models was chosen to simulate the annular seal flow according to the state of rotor systems. The objective was to obtain a transient response of rotor systems under the influence of fluid-induced forces generated by annular seal flow. This method overcomes some shortcomings of the traditional FSI method by improving the data transfer process between two domains. Calculated results were in good agreement with the experimental results. The annular seal was shown to have a supportive effect on rotor systems. Furthermore, decreasing the seal clearance would enhance this supportive effect. In the transient process, vibration amplitude and critical speed largely changed when the acceleration of the rotor system increased.

  8. HAMLET forms annular oligomers when deposited with phospholipid monolayers.

    Science.gov (United States)

    Baumann, Anne; Gjerde, Anja Underhaug; Ying, Ming; Svanborg, Catharina; Holmsen, Holm; Glomm, Wilhelm R; Martinez, Aurora; Halskau, Oyvind

    2012-04-20

    Recently, the anticancer activity of human α-lactalbumin made lethal to tumor cells (HAMLET) has been linked to its increased membrane affinity in vitro, at neutral pH, and ability to cause leakage relative to the inactive native bovine α-lactalbumin (BLA) protein. In this study, atomic force microscopy resolved membrane distortions and annular oligomers (AOs) produced by HAMLET when deposited at neutral pH on mica together with a negatively charged lipid monolayer. BLA, BAMLET (HAMLET's bovine counterpart) and membrane-binding Peptide C, corresponding to BLA residues 75-100, also form AO-like structures under these conditions but at higher subphase concentrations than HAMLET. The N-terminal Peptide A, which binds to membranes at acidic but not at neutral pH, did not form AOs. This suggests a correlation between the capacity of the proteins/peptides to integrate into the membrane at neutral pH-as observed by liposome content leakage and circular dichroism experiments-and the formation of AOs, albeit at higher concentrations. Formation of AOs, which might be important to HAMLET's tumor toxic action, appears related to the increased tendency of the protein to populate intermediately folded states compared to the native protein, the formation of which is promoted by, but not uniquely dependent on, the oleic acid molecules associated with HAMLET.

  9. The Southern Annular Mode: a comparison of indices

    Directory of Open Access Journals (Sweden)

    M. Ho

    2012-03-01

    Full Text Available The Southern Annular Mode (SAM has been identified as a climate mechanism with potentially significant impacts on the Australian hydroclimate. However, despite the identification of relationships between SAM and Australia's hydroclimate using certain data sets, and focussed on certain time periods, the association has not been extensively explored and significant uncertainties remain. One reason for this is the existence of numerous indices, methods and data sets by which SAM has been approximated. In this paper, the various SAM definitions and indices are reviewed and the similarities and discrepancies are discussed, along with the strengths and weaknesses of each index development approach. Further, the sensitivity of the relationship between SAM and Australian rainfall to choice of SAM index is quantified and recommendations are given as to the most appropriate index to use when assessing the impacts of the SAM on Australia's hydroclimate. Importantly this study highlights the need to consider the impact that the choice of SAM index, and data set used to calculate the index, has on the outcomes of any SAM attribution study.

  10. Annular beam shaping system for advanced 3D laser brazing

    Science.gov (United States)

    Pütsch, Oliver; Stollenwerk, Jochen; Kogel-Hollacher, Markus; Traub, Martin

    2012-10-01

    As laser brazing benefits from advantages such as smooth joints and small heat-affected zones, it has become established as a joining technology that is widely used in the automotive industry. With the processing of complex-shaped geometries, recent developed brazing heads suffer, however, from the need for continuous reorientation of the optical system and/or limited accessibility due to lateral wire feeding. This motivates the development of a laser brazing head with coaxial wire feeding and enhanced functionality. An optical system is designed that allows to generate an annular intensity distribution in the working zone. The utilization of complex optical components avoids obscuration of the optical path by the wire feeding. The new design overcomes the disadvantages of the state-of-the-art brazing heads with lateral wire feeding and benefits from the independence of direction while processing complex geometries. To increase the robustness of the brazing process, the beam path also includes a seam tracking system, leading to a more challenging design of the whole optical train. This paper mainly discusses the concept and the optical design of the coaxial brazing head, and also presents the results obtained with a prototype and selected application results.

  11. Experimental investigation of the low NOx vortex airblast annular combustor

    Science.gov (United States)

    Johnson, S. M.; Biaglow, J. A.; Smith, J. M.

    1984-01-01

    A low oxides of nitrogen vortex airblast annular combustor was evaluated which has attained the goal of 1 gm NO2/kg fuel or less during operation. The experimental combustor test conditions were a nominal inlet-air temperature of 703 K, inlet total pressures between 0.52 to 0.83 MPa, and a constant inlet Mach number of 0.26. Exit temperature pattern factors for all test points were between 0.16 and 0.20 and exit swirl flow angles were 47 degrees at isothermal conditions and 23 degrees during combustion. Oxides of nitrogen did not exceed 1.05 gm NO2/kg fuel at the highest inlet pressure and exhaust temperature tested. Previous correlations have related NOx proportionally to the combustor inlet pressure raised to some exponent. In this experiment, a band of exponents between 0.5 and 1.0 resulted for fuel-air ratios from 0.023 to 0.027 and inlet pressures from 0.52 to 0.83 MPa. Previously announced in STAR as N84-22567

  12. Criticality Benchmark Analysis of the HTTR Annular Startup Core Configurations

    International Nuclear Information System (INIS)

    One of the high priority benchmarking activities for corroborating the Next Generation Nuclear Plant (NGNP) Project and Very High Temperature Reactor (VHTR) Program is evaluation of Japan's existing High Temperature Engineering Test Reactor (HTTR). The HTTR is a 30 MWt engineering test reactor utilizing graphite moderation, helium coolant, and prismatic TRISO fuel. A large amount of critical reactor physics data is available for validation efforts of High Temperature Gas-cooled Reactors (HTGRs). Previous international reactor physics benchmarking activities provided a collation of mixed results that inaccurately predicted actual experimental performance.1 Reevaluations were performed by the Japanese to reduce the discrepancy between actual and computationally-determined critical configurations.2-3 Current efforts at the Idaho National Laboratory (INL) involve development of reactor physics benchmark models in conjunction with the International Reactor Physics Experiment Evaluation Project (IRPhEP) for use with verification and validation methods in the VHTR Program. Annular cores demonstrate inherent safety characteristics that are of interest in developing future HTGRs.

  13. MCNP/MCNPX model of the annular core research reactor.

    Energy Technology Data Exchange (ETDEWEB)

    DePriest, Kendall Russell; Cooper, Philip J.; Parma, Edward J., Jr. (.,; .)

    2006-10-01

    Many experimenters at the Annular Core Research Reactor (ACRR) have a need to predict the neutron/gamma environment prior to testing. In some cases, the neutron/gamma environment is needed to understand the test results after the completion of an experiment. In an effort to satisfy the needs of experimenters, a model of the ACRR was developed for use with the Monte Carlo N-Particle transport codes MCNP [Br03] and MCNPX [Wa02]. The model contains adjustable safety, transient, and control rods, several of the available spectrum-modifying cavity inserts, and placeholders for experiment packages. The ACRR model was constructed such that experiment package models can be easily placed in the reactor after being developed as stand-alone units. An addition to the 'standard' model allows the FREC-II cavity to be included in the calculations. This report presents the MCNP/MCNPX model of the ACRR. Comparisons are made between the model and the reactor for various configurations. Reactivity worth curves for the various reactor configurations are presented. Examples of reactivity worth calculations for a few experiment packages are presented along with the measured reactivity worth from the reactor test of the experiment packages. Finally, calculated neutron/gamma spectra are presented.

  14. Flow Pressure Loss through Straight Annular Corrugated Pipes

    Science.gov (United States)

    Sargent, Joseph R.; Kirk, Daniel R.; Marsell, Brandon; Roth, Jacob; Schallhorn, Paul A.; Pitchford, Brian; Weber, Chris; Bulk, Timothy

    2016-01-01

    Pressure loss through annular corrugated pipes, using fully developed gaseous nitrogen representing purge pipes in spacecraft fairings, was studied to gain insight into a friction factor coefficient for these pipes. Twelve pipes were tested: four Annuflex, four Masterflex and two Titeflex with ¼”, 3/8”, ½” and ¾” inner diameters. Experimental set-up was validated using smooth-pipe and showed good agreement to the Moody diagram. Nitrogen flow rates between 0-200 standard cubic feet per hour were used, producing approximate Reynolds numbers from 300-23,000. Corrugation depth varied from 0.248 = E/D = 0.349 and relative corrugation pitch of 0.192 = P/D = 0.483. Differential pressure per unit length was measured and calculated using 8-9 equidistant pressure taps. A detailed experimental uncertainty analysis, including correlated bias error terms, is presented. Results show larger differential pressure losses than smooth-pipes with similar inner diameters resulting in larger friction factor coefficients.

  15. Modeling and analysis of thermoacoustic instabilities in an annular combustor

    Science.gov (United States)

    Murthy, Sandeep; Sayadi, Taraneh; Le Chenadec, Vincent; Schmid, Peter

    2015-11-01

    A simplified model is introduced to study thermo-acoustic instabilities in axisymmetric combustion chambers. Such instabilities can be triggered when correlations between heat-release and pressure oscillations exist, leading to undesirable effects. Gas turbine designs typically consist of a periodic assembly of N identical units; as evidenced by documented studies, the coupling across sectors may give rise to unstable modes, which are the highlight of this study. In the proposed model, the governing equations are linearized in the acoustic limit, with each burner modeled as a one-dimensional system, featuring acoustic damping and a compact heat source. The coupling between the burners is accounted for by solving the two-dimensional wave equation over an annular region, perpendicular to the burners, representing the chamber's geometry. The discretization of these equations results in a set of coupled delay-differential equations, that depends on a finite set of parameters. The system's periodicity is leveraged using a recently developed root-of-unity formalism (Schmid et al., 2015). This results in a linear system, which is then subjected to modal and non-modal analysis to explore the influence of the coupled behavior of the burners on the system's stability and receptivity.

  16. Current Density Measurements of an Annular-Geometry Ion Engine

    Science.gov (United States)

    Shastry, Rohit; Patterson, Michael J.; Herman, Daniel A.; Foster, John E.

    2012-01-01

    The concept of the annular-geometry ion engine, or AGI-Engine, has been shown to have many potential benefits when scaling electric propulsion technologies to higher power. However, the necessary asymmetric location of the discharge cathode away from thruster centerline could potentially lead to non-uniformities in the discharge not present in conventional geometry ion thrusters. In an effort to characterize the degree of this potential non-uniformity, a number of current density measurements were taken on a breadboard AGI-Engine. Fourteen button probes were used to measure the ion current density of the discharge along a perforated electrode that replaced the ion optics during conditions of simulated beam extraction. Three Faraday probes spaced apart in the vertical direction were also used in a separate test to interrogate the plume of the AGI-Engine during true beam extraction. It was determined that both the discharge and the plume of the AGI-Engine are highly uniform, with variations under most conditions limited to +/-10% of the average current density in the discharge and +/-5% of the average current density in the plume. Beam flatness parameter measured 30 mm from the ion optics ranged from 0.85 - 0.95, and overall uniformity was shown to generally increase with increasing discharge and beam currents. These measurements indicate that the plasma is highly uniform despite the asymmetric location of the discharge cathode.

  17. Criticality Benchmark Analysis of the HTTR Annular Startup Core Configurations

    Energy Technology Data Exchange (ETDEWEB)

    John D. Bess

    2009-11-01

    One of the high priority benchmarking activities for corroborating the Next Generation Nuclear Plant (NGNP) Project and Very High Temperature Reactor (VHTR) Program is evaluation of Japan's existing High Temperature Engineering Test Reactor (HTTR). The HTTR is a 30 MWt engineering test reactor utilizing graphite moderation, helium coolant, and prismatic TRISO fuel. A large amount of critical reactor physics data is available for validation efforts of High Temperature Gas-cooled Reactors (HTGRs). Previous international reactor physics benchmarking activities provided a collation of mixed results that inaccurately predicted actual experimental performance.1 Reevaluations were performed by the Japanese to reduce the discrepancy between actual and computationally-determined critical configurations.2-3 Current efforts at the Idaho National Laboratory (INL) involve development of reactor physics benchmark models in conjunction with the International Reactor Physics Experiment Evaluation Project (IRPhEP) for use with verification and validation methods in the VHTR Program. Annular cores demonstrate inherent safety characteristics that are of interest in developing future HTGRs.

  18. Measurement of large aspheric surfaces by annular subaperture stitching interferometry

    Institute of Scientific and Technical Information of China (English)

    Xiaokun Wang; Lihui Wang; Longhai Yin; Binzhi Zhang; Di Fan; Xuejun Zhang

    2007-01-01

    A new method for testing aspheric surfaces by annular subaperture stitching interferometry is introduced.It can test large-aperture and large-relative-aperture aspheric surfaces at high resolution, low cost, and high efficiency without auxiliary null optics. The basic principle of the method is described, the synthetical optimization stitching model and effective algorithm are established based on simultaneous least-square fitting. A hyperboloid with an aperture of 350 mm is tested by this method. The obtained peak-to-valley (PV) and root-mean-square (RMS) values of the surface error after stitching are 0.433λ and 0.052λ (λis 632.8 nm), respectively. The reconstructed surface map is coincide with the entire surface map from null test, and the difference of PV and RMS errors between them are 0.031λ and 0.005λ, respectively.This stitching model provides another quantitive method for testing large aspheric surfaces besides null compensation.

  19. Characterization of Novel Calorimeters in the Annular Core Research Reactor

    Science.gov (United States)

    Hehr, Brian D.; Parma, Edward J.; Peters, Curtis D.; Naranjo, Gerald E.; Luker, S. Michael

    2016-02-01

    A series of pulsed irradiation experiments have been performed in the central cavity of Sandia National Laboratories' Annular Core Research Reactor (ACRR) to characterize the responses of a set of elemental calorimeter materials including Si, Zr, Sn, Ta, W, and Bi. Of particular interest was the perturbing effect of the calorimeter itself on the ambient radiation field - a potential concern in dosimetry applications. By placing the calorimeter package into a neutron-thermalizing lead/polyethylene (LP) bucket and irradiating both with and without a cadmium wrapper, it was demonstrated that prompt capture gammas generated inside the calorimeters can be a significant contributor to the measured dose in the active disc region. An MCNP model of the experimental setup was shown to replicate measured dose responses to within 10%. The internal (n,γ) contribution was found to constitute as much as 50% of the response inside the LP bucket and up to 20% inside the nominal (unmodified) cavity environment, with Ta and W exhibiting the largest enhancement due to their sizable (n,γ) cross sections. Capture reactions in non-disc components of the calorimeter were estimated to be responsible for up to a few percent of the measured response. This work was supported by the United States Department of Energy under Contract DE-AC04-94AL85000. Sandia is a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy.

  20. An Unusual Presentation of Annular Pancreas: A Case Report

    Directory of Open Access Journals (Sweden)

    Saleheh Ala

    2015-01-01

    Full Text Available Abstract Annular pancreas (AP is a rare congenital malformation resulting from failure of pancreas ventral anlage rotation with the duodenum. This leads to a ring of pancreatic tissue that envelops the duodenum. Clinical manifestations of AP most commonly develop in infancy or early childhood but can present at any age. The diagnosis of AP, usually suggested by an upper GI series or abdominal CT scan, but surgery is considered the gold standard diagnostic method. Surgical bypass of the annulus in all patients with symptomatic AP is recommended. We report a one year old girl who presented with intermittent, non projectile, non bilious vomiting that occurred 1h to 2h after feeding since neonatal period. Upper GI contrast study demonstrates, a dilated duodenal bulb associated with narrowing of post bulbar area. The patient underwent surgical correction of the obstruction. A bypass of the ectopic pancreas tissue was performed by duodenoduodenostomy. Considering the rarity of this congenital abnormality, presenting with chronic partial duodenal obstruction, and its successful correction by surgical means have prompted us to report the case.

  1. Learn About Stem Cells

    Science.gov (United States)

    ... PDF) Download an introduction to stem cells and stem cell research. Stem Cell Glossary Stem cell terms to know. ... ISSCR Get Involved Media © 2015 International Society for Stem Cell Research Terms of Use Disclaimer Privacy Policy

  2. Stem Cell Basics

    Science.gov (United States)

    ... Information Stem Cell Basics Stem Cell Basics: Introduction Stem Cell Information General Information Clinical Trials Funding Information Current Research Policy Glossary Site Map Stem Cell Basics Introduction: What are stem cells, and why ...

  3. Hydraulic study of drilling fluid flow in circular and annular tubes

    Energy Technology Data Exchange (ETDEWEB)

    Scheid, C.M.; Calcada, L.A.; Braga, E.R.; Paraiso, E.C.H. [Universidade Federal Rural do Rio de Janeiro (PPGEQ/UFRRJ), Seropedica, RJ (Brazil). Programa de Pos-Graduacao em Engenharia Quimica. Dept. de Engenharia Qumica], E-mail: calcada@ufrrj.br; Martins, A. L. [Petroleo Brasileiro S.A. (CENPES/PETROBRAS), Rio de Janeiro, RJ (Brazil). Centro de Pesquisas

    2011-10-15

    This study investigates the drilling fluid flow behavior of two water-based drilling fluids in circular and annular tubes. The study has four main objectives: 1) to evaluate correlations between the Power Law and the Casson rheological models, 2) to characterize the flow behavior, 3) to evaluate five hydraulic-diameter equations, and 4) to evaluate the correlations of five turbulent flow-friction factors. The experimental fluid flow loop consisted of one positive displacement pump of 25 HP connected to a 500-liter tank agitated by a 3-HP mixer. The fluids passed through six meters long tubes, arranged in three horizontal rows with independent inlets and outlets. The circular tubes had a 1 inch diameter and were configured as two concentric annular tubes. Annular Tube I had an outer diameter of 1 1/4 inch and an inner diameter of 1/2 inch. Annular Tube II had an outer diameter of 2 inches and an inner diameter of 3/4 inch. The results show that, for the fluids in exam, correlations proposed in the literature were inaccurate as far as predicting hydraulic diameter, estimating pressure drop, and defining the flow regime. In general, the performance of those correlations depended on the fluid properties and on the system's geometry. Finally, literature parameters for some of the correlations were estimated for the two drilling fluids studied. These estimations improved the predictive capacity of calculating the friction factor for real drilling fluids applications for both circular and annular tubes. (author)

  4. Time delay controlled annular array transducers for omnidirectional guided wave mode control in plate like structures

    International Nuclear Information System (INIS)

    Guided waves in plate like structures offer several modes with unique characteristics that can be taken advantage for nondestructive inspection applications. Conditions relating to the structure under inspection like the surrounding media, liquid loading, coatings etc require the use of special modes for successful inspection. Therefore, transducers that can excite mode controlled guided waves are essential for defect detection and discrimination in structures. Array transducers with annular elements can generate omnidirectional guided waves in plate like structures. However, the wave modes excited are limited to a particular wavelength governed by the element spacing. This limitation on the annular array transducers can be overcome by controlling the phase at each element relative to one another. In this work, annular array transducer construction techniques are theoretically examined and the optimum phase delays between the annular elements to excite a desired guided wave mode are calculated. A five element comb type annular array transducer is fabricated utilizing 1–3 type piezocomposite material. The mode control capability of the transducer is experimentally verified by selectively exciting the A0 and S0 guided wave modes in an aluminum plate like structure. (paper)

  5. Repeated mitral valve replacement in a patient with extensive annular calcification

    Directory of Open Access Journals (Sweden)

    Kitamura Tadashi

    2011-11-01

    Full Text Available Abstract Background Mitral valve replacement in the presence of severe annular calcification is a technical challenge. Case report A 47-year-old lady who had undergone mitral and aortic valve replacement for rheumatic disease 27 years before presented with dyspnea. At reoperation, extensive mitral annular calcification was hindering the disc motion of the Starr-Edwards mitral prosthesis. The old prosthesis was removed and a St Jude Medical mechanical valve was implanted after thorough annular debridement. Postoperatively the patient developed paravalvular leak and hemolytic anemia, subsequently undergoing reoperation three days later. The mitral valve was replaced with an Edwards MIRA valve, with a bulkier sewing cuff, after more aggressive annular debridement. Although initially there was no paravalvular leak, it recurred five days later. The patient also developed a small cerebral hemorrhage. As the paravalvular leak and hemolytic anemia gradually worsened, the patient underwent reoperation 14 days later. A Carpentier-Edwards bioprosthetic valve with equine pericardial patches, one to cover the debrided calcified annulus, another as a collar around the prosthesis, was used to eliminate paravalvular leak. At 7 years postoperatively the patient is doing well without any evidence of paravalvular leak or structural valve deterioration. Conclusion Mitral valve replacement using a bioprosthesis with equine pericardial patches was useful to overcome recurrent paravalvular leak due to severe mitral annular calcification.

  6. The clinical application of “jetting suture” technique in annular repair under microendoscopic discectomy

    Science.gov (United States)

    Qi, Lei; Li, Mu; Si, Haipeng; Wang, Liang; Jiang, Yunpeng; Zhang, Shuai; Li, Le

    2016-01-01

    Abstract To introduce a new designed suture technique in annular repair under the microendoscopic discectomy (MED) surgery and to evaluate the clinical application of the technique in annular repair under MED with at least 2-year follow-up period. A new method of annular repair was designed and named “jetting suture” technique. Thirty consecutive patients with lumbar disc herniation were enrolled in the prospective single-cohort observational study. Patients were followed up at intervals of preoperative, postoperative 1 week, 3 months, 6 months, 1 year, and last follow-up. The clinical outcomes were evaluated by using Japanese Orthopaedic Association (JOA) score, Oswestry Disability Index, and modified Mcnab criteria. The procedure was successfully performed in all cases. No case required conversion to an open procedure. The mean age of patients was 36.6 years. Average blood loss was 45.8 ± 10.2 mL. The preoperative symptoms were alleviated significantly after surgery. All the standardized measures improved significantly at the last follow-up, including JOA score (10.1 to 26.6; P disc herniation was reported. The designed “jetting suture” technique in annular repair under MED can be performed safely and effectively. It could be a viable alternative to annular repair under lumbar discectomy. PMID:27495101

  7. Exploring flocculation of suspended burned sediment using an annular flume

    Science.gov (United States)

    Blake, W. H.; Clarke, P.; Manning, A. J.; Fitzsimons, M. F.

    2010-05-01

    The frequency and severity of wildfire events are predicted to increase in many fire-prone areas of the world with implications for erosion, sediment transport and sedimentation. While cohesive suspended sediment is known to be transported primarily as flocculated material in river channels, with important implications for catchment nutrient and contaminant fluxes, there has been little work to date to explore the effect of burning on suspended sediment flocculation processes. Since heating has profound effects on surface soil biogeochemistry, it can be hypothesised that in-channel flocculation processes may also be affected as burned eroded material is transported through the catchment system. Using an annular flume and LISST-ST (Laser in Situ Scatter and Transmissometry with Settling Tube) particle size analyser, short-term suspended sediment flocculation dynamics were examined in burned and unburned sediment collected from a wildfire-impacted catchment, Southern Peloponnese, Greece. Fine sediment (stresses (0.1, 0.3, 0.6 and 0.9 Pa). Experiments were undertaken for a range of suspended sediment concentrations (111, 222 and 333 mg l-1) of burned and unburned material. For each shear and sediment concentration scenario, the flume was operated for 30 minutes to induce a theoretical equilibrium between flocs and fluid shear stress after which 5 replicate subsamples were collected and analysed for effective particle size using the LISST-ST. Material was also analysed for absolute particle size following chemical and ultrasonic dispersion. At the two higher sediment concentrations, the effective particle size distribution of unburned material notably coarsened at shear stresses of 0.1-0.3 Pa in comparison to the absolute particle size distribution. This is reflected in a reduction of the percentage of 250 μm) e.g. from 14.4 ± 4.1 % to 5.9 ± 2.0 % at the highest sediment concentration. While similar increases in effective particle size were seen at the lower

  8. Transverse bed slope effects in an annular flume

    Science.gov (United States)

    Baar, Anne; Kleinhans, Maarten; de Smit, Jaco; Uijttewaal, Wim

    2016-04-01

    Large scale morphology, in particular bar dimensions and bifurcation dynamics, are greatly affected by the deflection of sediment transport on transverse bed slopes due to gravity and by helical flows. However, existing transverse bed slope predictors are based on a small set of experiments with a minor range of flow conditions and sediment sizes, and do not account for the presence of bedforms. In morphological modelling the deflection angle is therefore often calibrated on measured morphology. Our objective is to experimentally quantify the transverse slope effect for a large range of near-bed flow conditions and sediment sizes (0.17 - 4 mm) to test existing predictors, in order to improve morphological modelling of rivers and estuaries. We have conducted about 400 experiments in an annular flume, which functions as an infinitely long bended flume and therefore avoids boundary effects. Flow is generated by rotating the lid of the flume, while the intensity of the helical flow can be decreased by counterrotating the bottom of the flume. The equilibrium transverse slope that develops during the experiments is a balance between the transverse bed slope effect and the bed shear stress caused by the helical flow. We obtained sediment mobilities from no motion to sheet flow, ranging across bedload and suspended load. Resulting equilibrium transverse slopes show a clear trend with varying sediment mobilities and helical flow intensities that deviate from typical power relations with Shields number. As an end member we found transversely horizontal beds by counterrotation that partially cancelled the helical flow near the bed, which allows us to quantify helical flow. The large range in sediment mobilities caused different bed states from ripples and dunes to sheet flow that affect near-bed flow, which cause novel nonlinear relations between transverse slope and Shields number. In conclusion, our results show for a wide range of conditions and sediments that transverse

  9. Hybrid multiphase CFD simulation for liquid-liquid interfacial area prediction in annular centrifugal contactors

    International Nuclear Information System (INIS)

    Liquid-liquid contacting equipment used in solvent extraction processes has the dual purpose of mixing and separating two immiscible fluids. Consequently, such devices inherently encompass a wide variety of multiphase flow regimes. A hybrid multiphase computational fluid dynamics (CFD) solver which combines the Eulerian multi-fluid method with VOF (volume of fluid) sharp interface capturing has been developed for application to annular centrifugal contactors. This solver has been extended to enable prediction of mean droplet size and liquid-liquid interfacial area through a single moment population balance method. Simulations of liquid-liquid mixing in a simplified geometry and a model annular centrifugal contactor are reported with droplet breakup/coalescence models being calibrated versus available experimental data. Quantitative comparison is made for two different housing vane geometries and it is found that the predicted droplet size is significantly smaller for vane geometries which result in higher annular liquid holdup

  10. Hybrid multiphase CFD simulation for liquid-liquid interfacial area prediction in annular centrifugal contactors

    Energy Technology Data Exchange (ETDEWEB)

    Wardle, K.E. [Chemical Sciences and Engineering Division, Argonne National Laboratory, Argonne, IL 60439 (United States)

    2013-07-01

    Liquid-liquid contacting equipment used in solvent extraction processes has the dual purpose of mixing and separating two immiscible fluids. Consequently, such devices inherently encompass a wide variety of multiphase flow regimes. A hybrid multiphase computational fluid dynamics (CFD) solver which combines the Eulerian multi-fluid method with VOF (volume of fluid) sharp interface capturing has been developed for application to annular centrifugal contactors. This solver has been extended to enable prediction of mean droplet size and liquid-liquid interfacial area through a single moment population balance method. Simulations of liquid-liquid mixing in a simplified geometry and a model annular centrifugal contactor are reported with droplet breakup/coalescence models being calibrated versus available experimental data. Quantitative comparison is made for two different housing vane geometries and it is found that the predicted droplet size is significantly smaller for vane geometries which result in higher annular liquid holdup.

  11. Eosinophilic annular erythema: a subset of Wells' syndrome or a distinct entity?

    Science.gov (United States)

    Howes, Renae; Girgis, Laila; Kossard, Steven

    2008-08-01

    A 52-year-old woman with a 6-year history of a persistent non-pruritic cutaneous annular eruption, forming polycyclic and arcuate plaques that commenced as erythematous papules and nodules, is presented. Lethargy and arthralgia were associated symptoms. We have followed this patient for the last 3 years, and during this period she has continued to have a florid annular eruption of unknown cause. Laboratory tests, including an eosinophil count, examination of stool samples for parasites, and a computed tomography scan of the chest, abdomen and pelvis, failed to detect any abnormalities. Skin biopsies demonstrated a superficial to deep cellular infiltrate consisting of numerous eosinophils, with lymphocytes and isolated neutrophils. Eosinophilic dust, flame figures and granulomatous inflammation were not seen. In addition, strands of mucin were present through the dermis, and prominent basal vacuolar change was evident at the dermoepidermal junction; these features may represent new findings that help define a distinct form of eosinophilic annular erythema. PMID:18638225

  12. Pressure drop in fully developed, turbulent, liquid-vapor annular flows in zero gravity

    Science.gov (United States)

    Sridhar, K. R.; Chao, B. T.; Soo, S. L.

    1992-01-01

    The prediction of frictional pressure drop in fully developed, turbulent, annular liquid-vapor flows in zero gravity using simulation experiments conducted on earth is described. The scheme extends the authors' earlier work on dispersed flows. The simulation experiments used two immiscible liquids of identical density, namely, water and n-butyl benzoate. Because of the lack of rigorous analytical models for turbulent, annular flows, the proposed scheme resorts to existing semiempirical correlations. Results based on two different correlations are presented and compared. Others may be used. It was shown that, for both dispersed and annular flow regimes, the predicted frictional pressure gradients in 0-g are lower than those in 1-g under otherwise identical conditions. The physical basis for this finding is given.

  13. Anti-oxidative therapy with oral dapsone improved HCV antibody positive annular elastolytic giant cell granuloma.

    Science.gov (United States)

    Igawa, K; Maruyama, R; Katayama, I; Nishioka, K

    1997-05-01

    A 72-year-old fisherman who was positive for the HCV antibody developed an annular, erythematous, infiltrated lesions on sun-exposed areas. The lesions were diagnosed as annular elastolytic giant cell granuloma both clinically and histologically. Topical corticosteroid and cryotherapy with liquid nitrogen for several months failed to improve the lesions. We then started dapsone, a known anti-oxidant, at 50 mg/day. A month later, the margins of the erythematous lesions faded, and the infiltration gradually decreased. No recurrence has been observed for one year after the start of the therapy. Anti-oxidative therapy appears to be effective for annular elastolytic giant cell granuloma and could be an alternate therapy for refractory granulomatous disease. PMID:9198323

  14. Diametric Tolerance Control of Dual Cooled Annular Fuel Pellet without Inner Surface Grinding

    International Nuclear Information System (INIS)

    A dual cooled fuel consists of internal and external cladding tubes in which annular pellets are stacked and cooling water flows in both internal and external coolant passages. It is recently being reconsidered as a promising option for a power up-rate of a pressurized water reactor fuel assembly because an annular fuel shows a lot of advantages from the point of a fuel safety and its economy due to an increased heat transfer area and a thin pellet thickness. Many technical issues might cause a serious problem to adopt the dual cooled annular fuel to the commercial PWR reactors. One of the most important issues is a heat flux split toward an internal cladding and an external cladding due to the gap conductance asymmetry which results from a preferential expansion of a fuel pellet toward the outside during an irradiation. Gap conductance is directly related to the inner and outer gap thicknesses. Initial gap thicknesses can vary with a pellet's dimensions which are affected by a reactor operation condition. Recently, it is suggested that a fuel rod with a smaller inner gap and a larger outer gap can reduce this gap conductance asymmetry. This approach can be effective only after precise tolerance technology is achieved. Because of an inhomogeneous green density distribution along the compact height, an hour-glassing usually occurred in a sintered cylindrical PWR fuel pellet fabricated by a conventional double-acting press. Thus, a sintered pellet usually undergoes a center-less grinding process in order to secure a pellet's specifications. In the case of an annular pellet fabrication using a conventional double-acting press, the same hour-glass shape would probably occur. The outer diameter tolerance of an annular pellet can be controlled easily similar to that of a conventional cylindrical PWR pellet through a center-less grinding. However, it appears not to be simple in the case of an inner surface grinding. It would be the best way to satisfy the specifications

  15. Tight focus of a radially polarized and amplitude-modulated annular multi-Gaussian beam

    International Nuclear Information System (INIS)

    The focusing of a radially polarized beam without annular apodization ora phase filter at the entrance pupil of the objective results in a wide focus and low purity of the longitudinally polarized component. However, the presence of a physical annular apodization or phase filter makes some applications more difficult or even impossible. We propose a radially polarized and amplitude-modulated annular multi-Gaussian beam mode. Numerical simulation shows that it can be focused into a sharper focal spot of 0.125λ2 without additional apodizations or filters. The beam quality describing the purity of longitudinally polarized component is up to 86%. (electromagnetism, optics, acoustics, heat transfer, classical mechanics, and fluid dynamics)

  16. Scintillation characteristics of annular beams propagating through atmospheric turbulence along a slanted path

    International Nuclear Information System (INIS)

    Scintillation characteristics of annular beams propagating through atmospheric turbulence along a slanted path are studied by using the numerical simulation method and some new results are obtained, which are explained in physical terms. It is found that, when the zenith angle is not large enough, the saturation phenomenon of the scintillation index never appears even if the propagation distance is large enough, which is quite different from the behavior for the horizontal propagation case. However, under the same condition (i.e. the zenith angle is not large enough), the on-axis scintillation index still approaches an asymptotical value, which increases as the zenith angle increases, and depends on the obscure ratio of annular beams. Furthermore, the relation of the on-axis scintillation index between annular beams and flat-topped beams is also examined in this paper. It is shown that their relation will change as the zenith angle changes. (paper)

  17. Modelling Air and Water Two-Phase Annular Flow in a Small Horizontal Pipe

    Science.gov (United States)

    Yao, Jun; Yao, Yufeng; Arini, Antonino; McIiwain, Stuart; Gordon, Timothy

    2016-06-01

    Numerical simulation using computational fluid dynamics (CFD) has been carried out to study air and water two-phase flow in a small horizontal pipe of an inner diameter of 8.8mm, in order to investigate unsteady flow pattern transition behaviours and underlying physical mechanisms. The surface liquid film thickness distributions, determined by either wavy or full annular flow regime, are shown in reasonable good agreement with available experimental data. It was demonstrated that CFD simulation was able to predict wavy flow structures accurately using two-phase flow sub-models embedded in ANSYS-Fluent solver of Eulerian-Eulerian framework, together with a user defined function subroutine ANWAVER-UDF. The flow transient behaviours from bubbly to annular flow patterns and the liquid film distributions revealed the presence of gas/liquid interferences between air and water film interface. An increase of upper wall liquid film thickness along the pipe was observed for both wavy annular and full annular scenarios. It was found that the liquid wavy front can be further broken down to form the water moisture with liquid droplets penetrating upwards. There are discrepancies between CFD predictions and experimental data on the liquid film thickness determined at the bottom and the upper wall surfaces, and the obtained modelling information can be used to assist further 3D user defined function subroutine development, especially when CFD simulation becomes much more expense to model full 3D two-phase flow transient performance from a wavy annular to a fully developed annular type.

  18. Histological study of the annular ligament in the rabbitfish eye (Siganus sp.

    Directory of Open Access Journals (Sweden)

    Marziye Asli

    2012-12-01

    Full Text Available Rabbitfish is economically valuable teleost species which lives in shallow coastalwaters. Two species of rabbit fish have been recognized in southern sea of Iran (Persiangulf as namely Siganus sutor and Siganus javus. In the current study, in order toinvestigate the histology of the annular ligament of the S. javus’ eye, the prepared sectionsof the eyes of twelve healthy specimens were studied under light microscope. The resultsrevealed that annular ligament is a crescent shape structure which is situated between thescleral stroma anteriorly and the iris posteriorly. It contains a vascularized, amorphousand granular matrix with fibers of dense connective tissue; high glycogen content andmelanin pigments.

  19. Experimental Study on Convective Boiling Heat Transfer in Vertical Narrow Gap Annular Tube

    Institute of Scientific and Technical Information of China (English)

    Li Bin; He Anding; Wang Yueshe; Zhou Fangde

    2001-01-01

    Experiments are conducted to investigate the characteristics of single-phase forced-flow convection and boiling heat transfer of R113 flowing through annular tube with gap of 1, 1.5 and 2.5 mm, and also the visualization test are carried out to get two-phase flow regime. The data show that the Nusselt numbers for the narrow-gap are higher than those predicted by traditional large channel correlation and boiling heat transfer is enhanced. Based on the data obtained in this investigation, correlations for single-phase, forced convection and flow boiling in annular tube of different gap size has been developed.

  20. Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

    Institute of Scientific and Technical Information of China (English)

    2008-01-01

    By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.

  1. Liquid–Liquid Mixing Studies in Annular Centrifugal Contactors Comparing Stationary Mixing Vane Options

    Energy Technology Data Exchange (ETDEWEB)

    Wardle, Kent E.

    2015-11-10

    Comparative studies of multiphase operation of annular centrifugal contactors showing the impact of housing stationary mixing vane configuration. A number of experimental results for several different mixing vane options are reported with selected measurements in a lab-scale 5 cm contactor and 12.5 cm engineering-scale unit. Fewer straight vanes give greater mixingzone hold-up compared to curved vanes. Quantitative comparison of droplet size distribution also showed a significant decrease in mean diameter for four straight vanes versus eight curved vanes. This set of measurements gives a compelling case for careful consideration of mixing vane geometry when evaluating hydraulic operation and extraction process efficiency of annular centrifugal contactors.

  2. Histological study of the annular ligament in the rabbitfish eye (Siganus sp.).

    Science.gov (United States)

    Asli, Marziye; Mansoori, Forooghsadat; Sattari, Amir

    2012-01-01

    Rabbitfish is economically valuable teleost species which lives in shallow coastal waters. Two species of rabbit fish have been recognized in southern sea of Iran (Persian gulf) as namely Siganus sutor and Siganus javus. In the current study, in order to investigate the histology of the annular ligament of the S. javus' eye, the prepared sections of the eyes of twelve healthy specimens were studied under light microscope. The results revealed that annular ligament is a crescent shape structure which is situated between the scleral stroma anteriorly and the iris posteriorly. It contains a vascularized, amorphous and granular matrix with fibers of dense connective tissue; high glycogen content and melanin pigments.

  3. Quasi-static transient thermal stresses in a thick annular disc

    Indian Academy of Sciences (India)

    V S Kulkarni; K C Deshmukh

    2007-10-01

    The present paper deals with the determination of transient thermal stresses in a thick annular disc. A thick annular disc is considered having zero initial temperature and subjected to arbitrary heat flux on the upper and lower surfaces where as the fixed circular edges are at zero temperature.The governing heat conduction equation have been solved by using integral transform technique. The results are obtained in series form in terms of Bessel’s functions. The results for displacement and stresses have been computed numerically and are illustrated graphically

  4. Generation of annular, high-charge electron beams at the Argonne wakefield accelerator

    Science.gov (United States)

    Wisniewski, E. E.; Li, C.; Gai, W.; Power, J.

    2013-01-01

    We present and discuss the results from the experimental generation of high-charge annular(ring-shaped)electron beams at the Argonne Wakefield Accelerator (AWA). These beams were produced by using laser masks to project annular laser profiles of various inner and outer diameters onto the photocathode of an RF gun. The ring beam is accelerated to 15 MeV, then it is imaged by means of solenoid lenses. Transverse profiles are compared for different solenoid settings. Discussion includes a comparison with Parmela simulations, some applications of high-charge ring beams,and an outline of a planned extension of this study.

  5. Radially polarized annular beam generated through a second-harmonic-generation process.

    Science.gov (United States)

    Sato, Shunichi; Kozawa, Yuichi

    2009-10-15

    A radially polarized beam with an annular intensity pattern was generated through a second-harmonic-generation process by focusing an azimuthally polarized Ti:sapphire pulsed laser beam to a c-cut beta-barium borate (BBO) crystal. The annular intensity pattern of the second-harmonic wave had a nearly sixfold symmetry as a result of the nonlinear susceptibility tensor of the BBO crystal. The width of the annulus was as narrow as less than 1/40th of its radius.

  6. An Evaluation of the Annular Fuel and Bottle-Shaped Fuel Concepts for Sodium Fast Reactors

    OpenAIRE

    Memmott, Matthew; Buongiorno, Jacopo; Hejzlar, Pavel

    2010-01-01

    Two innovative fuel concepts, the internally and externally cooled annular fuel and the bottle-shaped fuel, were investigated with the goal of increasing the power density and reduce the pressure drop in the sodium-cooled fast reactor, respectively. The concepts were explored for both high- and low-conversion core configurations, and metal and oxide fuels. The annular fuel concept is best suited for low-conversion metal-fuelled cores, where it can enable a power uprate of ~20%; the magnitude ...

  7. CFD Study of an Annular-Ducted Fan Lift System for VTOL Aircraft

    OpenAIRE

    Yun Jiang; Bo Zhang; Tao Huang

    2015-01-01

    The present study aimed at assessing a novel annular-ducted fan lift system for VTOL aircraft through computational fluid dynamics (CFD) simulations. The power and lift efficiency of the lift fan system in hover mode, the lift and drag in transition mode, the drag and flight speed of the aircraft in cruise mode and the pneumatic coupling of the tip turbine and jet exhaust were studied. The results show that the annular-ducted fan lift system can have higher lift efficiency compared to the ro...

  8. Radially polarized annular beam generated through a second-harmonic-generation process.

    Science.gov (United States)

    Sato, Shunichi; Kozawa, Yuichi

    2009-10-15

    A radially polarized beam with an annular intensity pattern was generated through a second-harmonic-generation process by focusing an azimuthally polarized Ti:sapphire pulsed laser beam to a c-cut beta-barium borate (BBO) crystal. The annular intensity pattern of the second-harmonic wave had a nearly sixfold symmetry as a result of the nonlinear susceptibility tensor of the BBO crystal. The width of the annulus was as narrow as less than 1/40th of its radius. PMID:19838261

  9. DETERMINATION OF TEMPERATURE DISTRIBUTION FOR ANNULAR FINS WITH TEMPERATURE DEPENDENT THERMAL CONDUCTIVITY BY HPM

    Directory of Open Access Journals (Sweden)

    Davood Domairry Ganji

    2011-01-01

    Full Text Available In this paper, homotopy perturbation method has been used to evaluate the temperature distribution of annular fin with temperature-dependent thermal conductivity and to determine the temperature distribution within the fin. This method is useful and practical for solving the nonlinear heat transfer equation, which is associated with variable thermal conductivity condition. The homotopy perturbation method provides an approximate analytical solution in the form of an infinite power series. The annular fin heat transfer rate with temperature-dependent thermal conductivity has been obtained as a function of thermo-geometric fin parameter and the thermal conductivity parameter describing the variation of the thermal conductivity.

  10. Evaluation Performance ofan Annular Composite Fin by UsingMATLAB Programming

    OpenAIRE

    Padma Lochannayak; suvendumohanty

    2015-01-01

    The aim of this project is analysis the efficiency ratio in an annular fin by the variation of heat transfer coefficient for any surface condition by using MATLAB software to calculate the base fin efficiency and the coated fin efficiency by the variation of heat transfer coefficient, radius ratio and base fin thickness of an annular fin and compare the coating fin efficiency to base fin efficiency. If the heat transfer coefficient is 50W/m2K the increase efficiency ratio is 10.46...

  11. On the levitation force in horizontal core-annular flow with a large viscosity ratio and small density ratio

    NARCIS (Netherlands)

    Ooms, G.; Pourquie, M.J.B.M.; Beerens, J.C.

    2013-01-01

    A numerical study has been made of horizontal core-annular flow: the flow of a high-viscosity liquid core surrounded by a low-viscosity liquid annular layer through a horizontal pipe. Special attention is paid to the question how the buoyancy force on the core, caused by a density difference between

  12. The effects of annular flow on dynamics of AP1000 reactor coolant pump rotor

    International Nuclear Information System (INIS)

    The feature of AP1000 RCP rotor system is that the whole rotor system is immersed in the annular flow. The rotor in annular flow induces fluctuating fluid forces, thereby causes vibration and noise, even rotor instability. The effects of annular flow on AP1000 RCP rotor system are different from that in bearings and seals and should be considered in a new approach. Based on the turbulent bulk flow theory and perturbation analysis, the rotor-flow coupled linear dynamic model is developed to predict the dynamics of AP1000 RCP immersed rotor. During the analysis, the rotor eccentricity, stator and rotor wall friction effects are emphasized. The analytic results show the rotor eccentricity induces divergence instability and significant decrease of instability speed for system with moderate or large eccentricity; however, stator and rotor wall friction effects distinctly suppress divergence instability and increase instability speed for system with small or moderate eccentricity. Finally, we can have the conclusion that the flow-structure interaction induced by annular flow has great effects on the dynamics of AP1000 RCP immersed rotor, which should be considered in rotor dynamic analysis and design of AP1000 RCP. The method and results in the paper have theoretical significance and practical importance. (author)

  13. Droplets in annular-dispersed gas-liquid pipe-flows

    NARCIS (Netherlands)

    Van 't Westende, J.M.C.

    2008-01-01

    Annular-dispersed gas-liquid pipe-flows are commonly encountered in many industrial applications, and have already been studied for many decades. However, due to the great complexity of this type of flow, there are still many phenomena that are poorly understood. The aim of this thesis is to shed mo

  14. The dispersive properties of a dielectricrod loaded waveguide immersed in a magnetized annular plasma

    Institute of Scientific and Technical Information of China (English)

    Li Wei; Gong Ma-Li; Wei Yan-Yu; Xie Hong-Quan

    2004-01-01

    @@ Propagation properties of electromagnetic waves in a dielectric-rod waveguide immersed in a magnetized annular plasma are presented in this paper. The dispersion relations are derived and calculated. The results show that the dielectric-rod loading can make the structure less dispersive and the transmission frequency-band broadened.

  15. Quench-induced trapping of magnetic flux in annular Josephson junctions

    DEFF Research Database (Denmark)

    Aarøe, Morten; Monaco, R.; Rivers, R.;

    2008-01-01

    The aim of the project is to investigate spontaneous symmetry breaking in non-adiabatic phase transitions (Kibble-Zurek processes). A long and narrow annular Josephson tunnel junction is subjected to repeated thermal quenches through the normal-superconducting transition. The quench rate is varie...

  16. Experimental critical parameters of enriched uranium solution in annular tank geometries

    International Nuclear Information System (INIS)

    A total of 61 critical configurations are reported for experiments involving various combinations of annular tanks into which enriched uranium solution was pumped. These experiments were performed at two widely separated times in the 1980s under two programs at the Rocky Flats Plant's Critical Mass Laboratory. The uranyl nitrate solution contained about 370 g of uranium per liter, but this concentration varied a little over the duration of the studies. The uranium was enriched to about 93% [sup 235]U. All tanks were typical of sizes commonly found in nuclear production plants. They were about 2 m tall and ranged in diameter from 0.6 m to 1.5 m. Annular thicknesses and conditions of neutron reflection, moderation, and absorption were such that criticality would be achieved with these dimensions. Only 13 of the entire set of 74 experiments proved to be subcritical when tanks were completely filled with solution. Single tanks of several radial thicknesses were studied as well as small line arrays (1 x 2 and 1 x 3) of annular tanks. Many systems were reflected on four sides and the bottom by concrete, but none were reflected from above. Many experiments also contained materials within and outside the annular regions that contained strong neutron absorbers. One program had such a thick external moderator/absorber combination that no reflector was used at all

  17. Testing the kibble-zurek scenario with annular josephson tunnel junctions

    Science.gov (United States)

    Kavoussanaki; Monaco; Rivers

    2000-10-16

    In parallel with Kibble's description of the onset of phase transitions in the early Universe, Zurek has provided a simple picture for the onset of phase transitions in condensed matter systems, supported by agreement with experiments in 3He and superconductors. We show how experiments with annular Josephson tunnel junctions can, and do, provide further support for this scenario.

  18. Displacement of one Newtonian fluid by another: density effects in axial annular flow

    DEFF Research Database (Denmark)

    Szabo, Peter; Hassager, Ole

    1997-01-01

    The arbitrary Lagrange-Euler (ALE) finite elementtechnique is used to simulate 3D displacement oftwo immiscible Newtonian fluids in vertical annular wells. For equally viscous fluids the effect of distinct fluid densities is investigated in the region of low to intermediate Reynolds numbers. Comp......, the efficiency of the displacement is analysed for various flow situations....

  19. A Case of Erythema Annulare Centrifigum with Sjögren Syndrome

    Directory of Open Access Journals (Sweden)

    İlgen Ertam

    2010-03-01

    Full Text Available Erythema annulare centrifigum is a dermatose which is frequently seen in adults. It is characterized by erythematous lesions which spread asymmetrically to periphery and have a collarette desquamation. Although infection, tumor, food allergy, drug reaction can play a role in the aetiology, most of the cases are idiopathic. A forty-nine years old, female patient presented to our clinic with erythematous lesions on both of her lower extremities. Six weeks prior to her referral, she treated with quinine for Sjogren syndrome. She had a diagnosis of granuloma annulare in her personal history. There was no significance in her family history. In dermatologic examination; annular erythematous plaques and collarette desquamation were detected on lower extremities. Histopathologic examination of the lesional biopsy specimen revealed focal spongiosis in the epidermis, dermal oedema, vascular proliferation and perivascular infiltration of lymphocytes, eosinophils and histiocytes. In the laboratory examination; blood count, liver and kidney function tests, sedimentation, C-reactive protein was normal. Rheumatoid factor was 30. Antinuclear antibody was 1/640 granular pattern. A case of erythema annulare centrifigum with Sjögren Syndrome is discussed with the other skin findings of the disease.

  20. Experimental critical parameters of enriched uranium solution in annular tank geometries

    Energy Technology Data Exchange (ETDEWEB)

    Rothe, R.E.

    1996-04-01

    A total of 61 critical configurations are reported for experiments involving various combinations of annular tanks into which enriched uranium solution was pumped. These experiments were performed at two widely separated times in the 1980s under two programs at the Rocky Flats Plant`s Critical Mass Laboratory. The uranyl nitrate solution contained about 370 g of uranium per liter, but this concentration varied a little over the duration of the studies. The uranium was enriched to about 93% [sup 235]U. All tanks were typical of sizes commonly found in nuclear production plants. They were about 2 m tall and ranged in diameter from 0.6 m to 1.5 m. Annular thicknesses and conditions of neutron reflection, moderation, and absorption were such that criticality would be achieved with these dimensions. Only 13 of the entire set of 74 experiments proved to be subcritical when tanks were completely filled with solution. Single tanks of several radial thicknesses were studied as well as small line arrays (1 x 2 and 1 x 3) of annular tanks. Many systems were reflected on four sides and the bottom by concrete, but none were reflected from above. Many experiments also contained materials within and outside the annular regions that contained strong neutron absorbers. One program had such a thick external moderator/absorber combination that no reflector was used at all.

  1. The influence of Thomson effect in the energy and exergy efficiency of an annular thermoelectric generator

    International Nuclear Information System (INIS)

    Highlights: • Exergy analysis in the annular thermoelectric generator (ATEG) system is proposed. • Analytical expressions for the power output, exergy efficiency of an ATEG is derived. • The effects of Sr, RL, and θ in Pout and exergy efficiency of an ATEG is studied. • The influence of Thomson effect in Pout and exergy efficiency of an ATEG is studied. - Abstract: The exoreversible thermodynamic model of an annular thermoelectric generator (ATEG) considering Thomson effect in conjunction with Peltier, Joule and Fourier heat conduction has been investigated using exergy analysis. New expressions for optimum current at the maximum power output and maximum energy, exergy efficiency conditions, and dimensionless irreversibilities in the ATEG are derived. The modified expression for figure of merit of a thermoelectric generator considering the Thomson effect has also been obtained. The results show that the power output, energy and exergy efficiency of the ATEG is lower than the flat plate thermoelectric generator. The effects of annular shape parameter (Sr = r2/r1), load resistance (RL), dimensionless temperature ratio (θ = Th/Tc) and the thermal and electrical contact resistances in power output, energy/exergy efficiency of the ATEG have been studied. It has also been proved that because of the influence of Thomson effect, the power output and energy/exergy efficiency of the ATEG is reduced. This study will help in the designing of the actual annular thermoelectric generation systems

  2. High quantum efficiency annular backside silicon photodiodes for reflectance pulse oximetry in wearable wireless body sensors

    DEFF Research Database (Denmark)

    Duun, Sune Bro; Haahr, Rasmus Grønbek; Hansen, Ole;

    2010-01-01

    The development of annular photodiodes for use in a reflectance pulse oximetry sensor is presented. Wearable and wireless body sensor systems for long-term monitoring require sensors that minimize power consumption. We have fabricated large area 2D ring-shaped silicon photodiodes optimized...

  3. Surgical treatment of annular pancreas in adults: a report of two cases

    Institute of Scientific and Technical Information of China (English)

    ZHENG He-ming; CAI Xiu-jun; SHEN Lai-gen; Robert Finley

    2007-01-01

    @@ A nnular pancreas is a congenital anomaly which consists of a ring of pancreatic tissue partially or completely encircling the descending portion of theduodenum. It was first described by Tiedemann1 in 1818 and named "annular pancreas" by Ecker2,3 in 1862.

  4. Existence, uniqueness and multiplicity of rotating fluxon waves in annular Josephson junctions

    OpenAIRE

    Katriel, Guy

    2007-01-01

    We prove that the equation modelling an annular Josephson junction has a rotating fluxon wave solution for all values of the parameters. We also obtain results on uniqueness of the rotating fluxon wave in some parameter regimes, and on multiplicity of rotating fluxon waves in other parameter regimes.

  5. LABORATORY AND NUMERICAL INVESTIGATIONS OF RESIDENCE TIME DISTRIBUTION OF FLUIDS IN LAMINAR FLOW STIRRED ANNULAR PHOTOREACTOR

    Science.gov (United States)

    Laboratory and Numerical Investigations of Residence Time Distribution of Fluids in Laminar Flow Stirred Annular PhotoreactorE. Sahle-Demessie1, Siefu Bekele2, U. R. Pillai11U.S. EPA, National Risk Management Research LaboratorySustainable Technology Division,...

  6. Experimental investigation of three-dimensional flow structures in annular swirling jets

    NARCIS (Netherlands)

    Percin, M.; Vanierschot, M.; Van Oudheusden, B.W.

    2015-01-01

    Annular jet flows are of practical interest in view of their occurrence in many industrial applications in the context of bluff-body combustors [1]. They feature different complex flow characteristics despite their simple geometry: a central recirculation zone (CRZ) as a result of flow separation be

  7. Acute renal infarction secondary to calcific embolus from mitral annular calcification.

    Science.gov (United States)

    Bande, Dinesh; Abbara, Suhny; Kalva, Sanjeeva P

    2011-06-01

    We report a case of a 62-year-old man who presented with right groin pain who subsequently was found to have a renal infarct secondary to calcific embolus from mitral annular calcification on CT and angiography. We briefly review the literature and discuss the importance of this entity in clinical practice.

  8. The analysis of the influence of the ferromagnetic rod in an annular magnetohydrodynamic (MHD pump

    Directory of Open Access Journals (Sweden)

    Bergoug Nassima

    2012-01-01

    Full Text Available This paper deals with the 2D modelisation of an annular induction magnetohydrodynamic (MHD pump using finite volume method in cylindrical coordinates and taking into consideration the saturation of the ferromagnetic material. The influence of the ferromagnetic rod on the different characteristics, in the channel of the MHD pump was studied in the paper.

  9. Stem Cells

    DEFF Research Database (Denmark)

    Sommerlund, Julie

    2004-01-01

    In his influential essay on markets, An essay on framing and overflowing (1998), Michel Callon writes that `the growing complexity of industrialized societies [is] due in large part to the movements of the technosciences, which are causing connections and interdependencies to proliferate'. This p...... and tantalizing than stem cells, in research, in medicine, or as products.......'. This paper is about tech-noscience, and about the proliferation of connections and interdependencies created by it.More specifically, the paper is about stem cells. Biotechnology in general has the power to capture the imagination. Within the field of biotechnology nothing seems more provocative...

  10. Why STEM?

    Science.gov (United States)

    Mitts, Charles R.

    2016-01-01

    The International Technology and Engineering Educators Association (ITEEA) defines STEM as a new transdisciplinary subject in schools that integrates the disciplines of science, technology, engineering, and mathematics into a single course of study. There are three major problems with this definition: There is no consensus in support of the ITEEA…

  11. 单、双环腔燃烧室燃烧性能的对比%Combustion Captibility Comparison of Single Annular Combustor and Dual Annular Combustor

    Institute of Scientific and Technical Information of China (English)

    李锋; 程明; 李龙贤; 彭浪青; 尚守堂

    2011-01-01

    In order to change a Single Annular Combustor(SAC) into a Dual Annular Combustor(DAC), the authors kept the diffuser,outer case and atomize of the SAC unchanged,redesigned the combustor from a single annular structure into a dual annular structure,and designed six different structure DAC. Taking the same physical models(including the turbulence, radiation, spray and emission models), simulations of three dimensional two-phase reacting turbulent flow in both the SAC and DAC were developed in the Fluent Code. The total-pressure recovery coefficient, temperature distribution and exhaust emission levels were given. Finally,by comparing the simulation results,the feasibility of displacing the SAC into DAC structure was certified.%保持单环腔主燃烧室的扩压器,外机匣最大直径尺寸以及喷口不变的前提下,将其火焰筒结构重新设计为并联式双环腔结构,设计了6种不同旋流器组合的双环腔结构燃烧室.采用相同的物理模型(包括湍流模型、辐射模型、喷雾模型及污染排放模型等),对单、双环腔主燃烧室分别进行全流程的三维计算.给出了燃烧室的总压恢复系数、燃烧效率、燃烧室出口温度分布系数、污染排放指标等燃烧室性能参数.对比分析了单、双环腔燃烧室的计算结果.结果表明,双环腔燃烧室置换单环腔燃烧室是可行的,该研究可为大飞机低污染大法动机的设计提供技术支持.

  12. Pluripotent stem cell lines

    OpenAIRE

    Yu, Junying; Thomson, James A.

    2008-01-01

    The derivation of human embryonic stem cells 10 years ago ignited an explosion of public interest in stem cells, yet this achievement depended on prior decades of research on mouse embryonic carcinoma cells and embryonic stem cells. In turn, the recent derivation of mouse and human induced pluripotent stem cells depended on the prior studies on mouse and human embryonic stem cells. Both human embryonic stem cells and induced pluripotent stem cells can self-renew indefinitely in vitro while ma...

  13. Perforating Granuloma Annulare — An Unusual Subtype of a Common Disease

    Directory of Open Access Journals (Sweden)

    João Alves

    2014-09-01

    Full Text Available Perforating granuloma annulare (GA is a rare subset of GA with an unknown etiology and chronic course. Herein, we report the case of 72 year-old women with a 3-month history of a post-traumatic, persistent, erythematous and exudative plaque located on her left leg. Differential diagnosis included mycobacterial infection, subcutaneous mycosis, perforating dermatoses, pyoderma and squamous cell carcinoma. The histopathology was highly suggestive of a perforating GA. The patient was treated with betamethasone dipropionate cream applied once daily and a complete resolution of the lesion was observed in three weeks. Despite being a very rare subtype of a common disease, perforating granuloma annulare has clinical and histopathological characteristic features that facilitate the differential diagnosis, avoiding unnecessary procedures and inadequate and potentially more invasive treatments.

  14. Experimental Study on the Characteristics of Liquid Layer and Disturbance Waves in Horizontal Annular Flow

    Institute of Scientific and Technical Information of China (English)

    1999-01-01

    The mechanism for transporting liquid from the bottom of the pipe to the top still to be established in the prediction of the film thickness distribution in horizontal annular two-phase flow.To resolve this issue,using five parallel-wire conductance probes,time records of local liquid film thickness at five circumferential positions were collected.The characteristics of circumferential liquid film thickness profiles and its variation with gas and liquid velocities were obtained.The basic features of probability distribution function,probability density function,auto-correlation,cross-correlation and power spectrum density function of the disturbance waves in annular flow were studied respectively.The characterstics of circumferential profiles of disturbance waves and its variation with gas and liquid velocities were presented.

  15. The Springtime North Asia Cyclone Activity Index and the Southern Annular Mode

    Institute of Scientific and Technical Information of China (English)

    YUE Xu; WANG Huijun

    2008-01-01

    The relationship between the North Asia cyclone (NAC) activity and the Southern Annular Mode (SAM) is documented in this research. The definition of the NAC index (NACI) is based on the atmospheric relative vorticity in North Asia. The analysis yields a significant positive correlation between previous winter Southern Annular Mode index (SAMI) and spring NACI in the interannual variability, with a correlation coefficient of 0.51 during 1948-2000. Analysis of the NAC-related and SAM-related atmospheric general circulation variability demonstrates such a relationship. The study further reveals that when the winter SAM becomes strong, the springtime atmospheric convection in tropical western Pacific will intensify and the local Hadley circulation will be strengthened. As a result, the abnormal subsiding motion over South China makes the temperature gradient intensified in the low level and strengthens the jet in the high level, both of which are beneficial to the development of NAC activity.

  16. Annular shape silver lined proportional counter for on-line pulsed neutron yield measurement

    Energy Technology Data Exchange (ETDEWEB)

    Dighe, P.M., E-mail: pmdighe@barc.gov.in; Das, D.

    2015-04-01

    An annular shape silver lined proportional counter is developed to measure pulsed neutron radiation. The detector has 314 mm overall length and 235 mm overall diameter. The central cavity of 150 mm diameter and 200 mm length is used for placing the neutron source. Because of annular shape the detector covers >3π solid angle of the source. The detector has all welded construction. The detector is developed in two halves for easy mounting and demounting. Each half is an independent detector. Both the halves together give single neutron pulse calibration constant of 4.5×10{sup 4} neutrons/shot count. The detector operates in proportional mode which gives enhanced working conditions in terms of dead time and operating range compared to Geiger Muller based neutron detectors.

  17. Annular core for modular high temperature gas-cooled reactor (MHTGR)

    International Nuclear Information System (INIS)

    The active core of the 350 MW(t) MHTGR is annular in configuration, shaped to provide a large external surface-to-volume ratio for the transport of heat radially to the reactor vessel in case of a loss of coolant flow. For a given fuel temperature limit, the annular core provides approximately 40 % greater power output over a typical cylindrical configuration. The reactor core is made up of columns of hexagonal blocks, each 793-mm high and 360-mm wide. The active core is 3.5 m in o.d., 1.65 m in i.d., and 7.93 m tall. Fuel elements contain TRISO-coated microspheres of 19.8 % enriched uranium oxycarbide and of fertile thorium oxide. The core is controlled by 30 control rods which enter the inner and outer side reflectors from above. (author)

  18. Gas turbine structural mounting arrangement between combustion gas duct annular chamber and turbine vane carrier

    Energy Technology Data Exchange (ETDEWEB)

    Wiebe, David J.; Charron, Richard C.; Morrison, Jay A.

    2016-10-18

    A gas turbine engine ducting arrangement (10), including: an annular chamber (14) configured to receive a plurality of discrete flows of combustion gases originating in respective can combustors and to deliver the discrete flows to a turbine inlet annulus, wherein the annular chamber includes an inner diameter (52) and an outer diameter (60); an outer diameter mounting arrangement (34) configured to permit relative radial movement and to prevent relative axial and circumferential movement between the outer diameter and a turbine vane carrier (20); and an inner diameter mounting arrangement (36) including a bracket (64) secured to the turbine vane carrier, wherein the bracket is configured to permit the inner diameter to move radially with the outer diameter and prevent axial deflection of the inner diameter with respect to the outer diameter.

  19. Annular flow of cement slurries; Escoamento anular de pastas de cimento

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Maria das Gracas Pena; Martins, Andre Leibsohn; Oliveira, Antonio Augusto J. de [PETROBRAS, Rio de Janeiro (Brazil). Centro de Pesquisas. Setor de Tecnologia de Perfuracao

    1989-12-31

    This paper considers the analysis of laminar, transitory and turbulent flow regimes of cement slurries of various compositions flowing in annular sections. It is an experimental study to evaluate the performance of dozens of equations found in the literature that reflect the rheological behavior of non-Newtonian fluids, the dimensioning of annular sections, the delimitation of the transitory zone and the estimative of friction losses in the turbulent flow regime. A large-scale physical simulator (SHS-Surface Hydraulic Simulator), was designed and constructed at the PETROBRAS Research Center in order to obtain flow parameters. A computer program capable of analysing and drawing conclusions from the behavior of non-Newtonian fluids flowing in different geometries and energetic conditions was also developed. These were considered as essential stages for the development of the project. (author) 17 refs., 9 figs., 18 tabs.

  20. THE PERTURBATION SOLUTIONS OF THE FLOW IN A ROTATING CURVED ANNULAR PIPE

    Institute of Scientific and Technical Information of China (English)

    2001-01-01

    In this paper, the flow in a rotating curved annular pipe isexamined by a perturbation method. A second order perturbation solution is presented. The characteristics of the secondary flow and the axial flow are studied in detail.The study indicates that the loops of the secondary flow are more complex than those in a curved annular pipe without rotation and its numbers depend on the ratio of the Coriolis force to centrifugal force F. As F ≈- 1 , the secondary flow has eight loops and its intensity reaches the minimum value, and the distribution of the axial flow is like that of the Poiseuille flow. The position of the maximum axial velocity is pushed to either outer bend or inner bend, which is also determined by F.

  1. Fully developed MHD natural convection flow in a vertical annular microchannel: An exact solution

    Directory of Open Access Journals (Sweden)

    Basant K. Jha

    2015-07-01

    Full Text Available An exact solution of steady fully developed natural convection flow of viscous, incompressible, electrically conducting fluid in a vertical annular micro-channel with the effect of transverse magnetic field in the presence of velocity slip and temperature jump at the annular micro-channel surfaces is obtained. Exact solution is expressed in terms of modified Bessel function of the first and second kind. The solution obtained is graphically represented and the effects of radius ratio (η, Hartmann number (M, rarefaction parameter (βvKn, and fluid–wall interaction parameter (F on the flow are investigated. During the course of numerical computations, it is found that an increase in Hartmann number leads to a decrease in the fluid velocity, volume flow rate and skin friction. Furthermore, it is found that an increase in curvature radius ratio leads to an increase in the volume flow rate.

  2. Annular shape silver lined proportional counter for on-line pulsed neutron yield measurement

    Science.gov (United States)

    Dighe, P. M.; Das, D.

    2015-04-01

    An annular shape silver lined proportional counter is developed to measure pulsed neutron radiation. The detector has 314 mm overall length and 235 mm overall diameter. The central cavity of 150 mm diameter and 200 mm length is used for placing the neutron source. Because of annular shape the detector covers >3π solid angle of the source. The detector has all welded construction. The detector is developed in two halves for easy mounting and demounting. Each half is an independent detector. Both the halves together give single neutron pulse calibration constant of 4.5×104 neutrons/shot count. The detector operates in proportional mode which gives enhanced working conditions in terms of dead time and operating range compared to Geiger Muller based neutron detectors.

  3. A Numerical and an Experimental Study for Optimization of a Small Annular Combustor

    Science.gov (United States)

    Iki, Norihiko; Gruber, Andrea; Yoshida, Hiro

    The small annular combustor of a micro gas turbine fueled with methane is investigated experimentally and numerically in order to improve the overall efficiency of the small engine. The CFD analysis of the tiny combustor relies on a low Reynolds number turbulence model coupled to the Eddy Dissipation Concept (EDC) and provides important insight about the turbulent flow pattern, flame shape, position and optimal flame anchoring. For the experimental observation, a model combustor, representing 120 degrees of the original annular combustor, is fabricated, which enables us to visualize internal flow. The burning area in the combustion chamber moves to downstream with increase of air flow rate. At full-load, some fuel remains at the combustion chamber exit. Moreover, temperatures are measured and compared with the numerical simulations. The results shown here will form the basis for future optimization of the micro gas turbine with minimal or no increase in combustor pressure loss.

  4. Stability analysis of a liquid fuel annular combustion chamber. M.S. Thesis

    Science.gov (United States)

    Mcdonald, G. H.

    1979-01-01

    The problems of combustion instability in an annular combustion chamber are investigated. A modified Galerkin method was used to produce a set of modal amplitude equations from the general nonlinear partial differential acoustic wave equation. From these modal amplitude equations, the two variable perturbation method was used to develop a set of approximate equations of a given order of magnitude. These equations were modeled to show the effects of velocity sensitive combustion instabilities by evaluating the effects of certain parameters in the given set of equations. By evaluating these effects, parameters which cause instabilities to occur in the combustion chamber can be ascertained. It is assumed that in the annular combustion chamber, the liquid propellants are injected uniformly across the injector face, the combustion processes are distributed throughout the combustion chamber, and that no time delay occurs in the combustion processes.

  5. A New Approach to Designing the S-Shaped Annular Duct for Industrial Centrifugal Compressor

    Directory of Open Access Journals (Sweden)

    Ivan Yurko

    2014-01-01

    Full Text Available The authors propose an analytical method for designing the inlet annular duct for an industrial centrifugal compressor using high-order Bezier curves. Using the design of experiments (DOE theory, the three-level full factorial design was developed for determination of influence of the dimensionless geometric parameters on the output criteria. Numerical research was carried out for determination of pressure loss coefficients and velocity swirl angles using the software system ANSYS CFX. Optimal values of the slope for a wide range of geometric parameters, allowing minimizing losses in the duct, have been found. The study has used modern computational fluid dynamics techniques to develop a generalized technique for future development of efficient variable inlet guide vane systems. Recommendations for design of the s-shaped annular duct for industrial centrifugal compressor have been given.

  6. The quantum spectral analysis of the two-dimensional annular billiard system

    Institute of Scientific and Technical Information of China (English)

    Zhang Yan-Hui; Zhang Ji-Ouan; Xu Xue-You; Lin Sheng-Lu

    2009-01-01

    Based on the extended closed-orbit theory together with spectral analysis, this paper studies the correspondence between quantum mechanics and the classical counterpart in a two-dimeusional annular billiard. The results demonstrate that the Fourier-transformed quantum spectra are in very good accordance with the lengths of the classical ballistic trajectories, whereas spectral strength is intimately associated with the shapes of possible open orbits connecting arbitrary two points in the annular cavity. This approach facilitates an intuitive understanding of basic quantum features such as quantum interference, locations of the wavefunctions, and allows quantitative calculations in the range of high energies, where full quantum calculations may become impractical in general. This treatment provides a thread to explore the properties of microjunction transport and even quantum chaos under the much more general system.

  7. Developments in fabrication of annular MOX fuel pellet for Indian fast reactor

    International Nuclear Information System (INIS)

    Mechanical rotary presses along with adoption of core rod feature were inducted for fabrication of intricate annular Mixed Oxide (MOX) pellets for Prototype Fast Breeder Reactor (PFBR). In the existing tooling, bottom plungers contain core rod whereas top plungers contain a central hole for the entry of core rod during compaction. Frequent manual clean up of top plungers after few operations were required due to settling of powder in the annular hole of top plungers during compaction. Delay in cleaning can also result in breakage of tooling apart from increase in the dose to extremities of personnel. New design of tooling has been introduced to clean up the top plungers online during the operation of rotary press. It leads to increase in the productivity, reduces the spillage of valuable nuclear material and also reduces man-rem to operators significantly. The present paper describes the modification in tooling design and compaction sequence established for online cleaning of top plungers. (author)

  8. Hydrodynamic characteristics of a novel annular spouted bed with multiple air nozzles

    Energy Technology Data Exchange (ETDEWEB)

    Gong, X.W.; Hu, G.X.; Li, Y.H. [Shanghai Jiao Tong University, Shanghai (China). School for Mechanical & Power Engineering

    2006-06-21

    A novel spouted bed, namely, an annular spouted bed with multiple air nozzles, has been proposed for drying, pyrolysis, and gasification of coal particulates. It consists of two homocentric upright cylinders with some annularly located spouting air nozzles between inner and outer cylinders. Experiments have been performed to study hydrodynamic characteristics of this device. The test materials studied are ash particle, soy bean, and black bean. Three distinct spouting stages have been examined and outlined with the hold-ups increase. In the fully developed spouting stage, three flow behaviors of particles have been observed and delimited. The effects of nozzle mode and spouting velocity on the maximum spouting height of the dense-phase region, spoutable static bed height, and spouting pressure drop in the bed have been investigated experimentally.

  9. ThO{sub 2}-UO{sub 2} annular pins for high burnup fuels

    Energy Technology Data Exchange (ETDEWEB)

    Caner, Marc; Dugan, Edward T

    2000-06-01

    The main purpose of this work is to investigate the use of annular fuel pins (particularly pins containing thorium dioxide) for high burnup fuel. The following parameters were evaluated and compared between postulated mixed thorium-uranium dioxide standard and annular (9% void fraction) type fuel assemblies, as a function of burnup: the infinite multiplication factor, the uranium and plutonium isotopic compositions, the fuel temperature coefficient of reactivity and the conversion ratio. We used the SCALE-4.3 code system. The calculation method consisted in obtaining actinide and fission product number densities as functions of assembly burnup, by means of a 1-D transport calculation combined with a 0-D burnup calculation. These number densities were then used in a 3-D Monte Carlo code for obtaining k{sub {infinity}} from two-dimensional-symmetry 'snapshots'.

  10. Experimental research on dryout point of flow boiling in narrow annular channels

    Institute of Scientific and Technical Information of China (English)

    2006-01-01

    An experimental research on the dryout point of flow boiling in narrow annular channels under low mass flux with 1.55 mm and 1.05 mm annular gap, respectively, is conducted. Distilled water is used as working fluid and the range of pressure is limited within 2.0~4.0 MPa and that of mass flux is 26.0~69.0 kg·m-2·s-1. The relation of critical heat flux (CHF) and critical qualities with mass flux and pressure are revealed. It is found that the critical qualities decrease with the increasing mass flux and increase with the increasing inlet qualities in externally heated annuli.Under the same conditions, critical qualities in the outer tube are always larger than those in the inner tube. The appearance of dryout point in bilaterally heated narrow annuli can be judged according to the ratio of qo/qi.

  11. The effect of inlet swirl on the dynamics of long annular seals in centrifugal pumps

    Science.gov (United States)

    Ismail, M.; Brown, R. D.; France, D.

    1994-01-01

    This paper describes additional results from a continuing research program which aims to identify the dynamics of long annular seals in centrifugal pumps. A seal test rig designed at Heriot-Watt University and commissioned at Weir Pumps Research Laboratory in Alloa permits the identification of mass, stiffness, and damping coefficients using a least-squares technique based on the singular value decomposition method. The analysis is carried out in the time domain using a multi-fiequency forcing function. The experimental method relies on the forced excitation of a flexibly supported stator by two hydraulic shakers. Running through the stator embodying two symmetrical balance drum seals is a rigid rotor supported in rolling element bearings. The only physical connection between shaft and stator is the pair of annular gaps filled with pressurized water discharged axially. The experimental coefficients obtained from the tests are compared with theoretical values.

  12. Annular Seals of High Energy Centrifugal Pumps: Presentation of Full Scale Measurement

    Science.gov (United States)

    Florjancic, S.; Stuerchler, R.; Mccloskey, T.

    1991-01-01

    Prediction of rotordynamic behavior for high energy concentration centrifugal pumps is a challenging task which still imposes considerable difficulties. While the mechanical modeling of the rotor is solved most satisfactorily by finite element techniques, accurate boundary conditions for arbitrary operating conditions are known for journal bearings only. Little information is available on the reactive forces of annular seals, such as neck ring and interstage seals and balance pistons, and on the impeller interaction forces. The present focus is to establish reliable boundary conditions at annular seals. For this purpose, a full scale test machine was set up and smooth and serrated seal configurations measured. Dimensionless coefficients are presented and compared with a state of the art theory.

  13. Numerical simulation of the transient temperature field from an annular focused ultrasonic transducer.

    Science.gov (United States)

    Zhang, Qiang; Li, Faqi; Feng, Ruo; Xu, Jianyi; Bai, Jin; Wang, Zhibiao; Wang, Yaojun

    2003-04-01

    Knowledge of the extent of the "heated necrosis element" from a single exposure in target tissue created by an ultrasonic beam is critical for the application of focal ultrasound (US) surgery (FUS). This study uses the O'Nell and Pennes formulas to simulate the heated necrosis element from an annular focused transducer and to examine its dependence on exposure dosage, as well as some design parameters of the transducer. Several conclusions may be drawn from our numerical results: 1. With increasing exposure, the heated necrosis element increases, but its contour becomes plumper and the influence of sound intensity I is found to be greater than that of the exposure time t. 2. To get a similar heated necrosis element, the exposure approximately satisfies a relation: It(0. 4 3)=constant. 3. Increasing the US frequency or the outer-radius of the annular transducer leads to a decrease in the heated necrosis volume. PMID:12749928

  14. Collective motion of symmetric camphor papers in an annular water channel

    Science.gov (United States)

    Ikura, Yumihiko S.; Heisler, Eric; Awazu, Akinori; Nishimori, Hiraku; Nakata, Satoshi

    2013-07-01

    We investigate the collective motion of symmetric self-propelled objects that are driven by a difference in the surface tension. The objects move around an annular water channel spontaneously and interact through the camphor layer that develops on the water surface. We found that two collective motion modes, discrete and continuous density waves, are generated depending on the number of self-propelled objects. The two modes are characterized by examining the local and global dynamics, and the collective motion mechanism is discussed in relation to the distribution of camphor concentration in the annular water channel. We conclude that the difference between these two modes originates from that of the driving mechanism that pushes a camphor paper away from a cluster, through which mechanism density waves are generated and maintained.

  15. LDA measurement of the passage flow field in an annular airfoil cascade

    Science.gov (United States)

    Stauter, R. C.; Fleeter, S.

    1987-01-01

    Models to predict the complex three-dimensional flow through turbomachine blade rows are being developed. To verify these models and direct necessary refinements, it is necessary that predictions be correlated with data obtained in experiments which model the fundamental three-dimensional blade row flow phenomena. This paper describes a series of experiments performed in a large scale, subsonic, annular cascade facility specifically designed to provide such data. In particular, the effect of incidence angle on the three-dimensional passage flow field through an annular cascade of cambered airfoils is investigated and quantified, accomplished by obtaining detailed and expensive LDA data. These data demonstrate and quantify the development of the passage vortices through the airfoil passage and their strong interaction with the endwall boundary layers.

  16. AXISYMMETRIC BENDING OF TWO-DIRECTIONAL FUNCTIONALLY GRADED CIRCULAR AND ANNULAR PLATES

    Institute of Scientific and Technical Information of China (English)

    Guojun Nie; Zheng Zhong

    2007-01-01

    Assuming the material properties varying with an exponential law both in the thickness and radial directions, axisymmetric bending of two-directional functionally graded circular and annular plates is studied using the semi-analytical numerical method in this paper. The deflections and stresses of the plates are presented. Numerical results show the well accuracy and convergence of the method. Compared with the finite element method, the semi-analytical numerical method is with great advantage in the computational efficiency. Moreover, study on axisymmetric bending of two-directional functionally graded annular plate shows that such plates have better performance than those made of isotropic homogeneous materials or one-directional functionally graded materials. Two-directional functionally graded material is a potential alternative to the one-directional functionally graded material. And the integrated design of materials and structures can really be achieved in two-directional functionally graded materials.

  17. Modifications to Marshall's Annular Seal Test (MAST) Rig and Facility for Improved Rotordynamic Coefficient Testing of Annular Seals and Fluid Film Bearings

    Science.gov (United States)

    Darden, J. M.; Earhart, E. M.

    2011-01-01

    The limits of rotordynamic stability continue to be pushed by the high power densities and rotational speeds of modern rocket engine turbomachinery. Destabilizing forces increase dramatically with rotor speed. Rotordynamic stability is lost when these destabilizing forces overwhelm the stabilizing forces. The vibration from the unstable rotor grows until it is limited by some nonlinearity. For example, a rolling element bearing with a stiffness characteristic that increases with deflection may limit the vibration amplitude. The loads and deflections resulting from this limit cycle vibration (LCV) can lead to bearing and seal damage which promotes ever increasing levels of subsynchronous vibration. Engineers combat LCV by introducing rotordynamic elements that generate increased stabilizing forces and reduced destabilizing forces. For example, replacing a labyrinth seal with a damping seal results in substantial increases in the damping and stiffness rotordynamic coefficients. Adding a swirl brake to the damping seal greatly reduces the destabilizing cross-coupled forces generated by the damping seal for even further increases in the stabilizing capacity. Marshall?s Annular Seal Test (MAST) rig is designed to experimentally measure the stabilizing capacity of new annular seal designs. The rig has been moved to a new facility and outfitted with a new slave bearing to allow increased test durations and to enable the testing of fluid film bearings. The purpose of this paper is to describe the new facility and the new bearing arrangement. Several novel seal and bearing designs will also be discussed.

  18. An usual elastophagocytic granuloma with involvement of the back: a possible variant of an annular elastolytic giant cell granuloma

    OpenAIRE

    Valdeolivas-Casillas, Nuria; Pulgar, Fernando; Dolores Velez, Maria; Polo-Rodriguez, Isabel; Quesada-Cortes, Alicia; Guirado-Koch, Cristina

    2015-01-01

    Annular elastolytic giant cell granuloma (AEGCG) is a very infrequent granulomatous dermatitis characterized by elastolysis and elastophagocytosis. It usually appears in middle-aged Caucasian women and is normally located in sun-exposed areas. We present a case of a 73-year-old woman with hypertension and type II diabetes, who was admitted to the hospital for an ischemic cerebrovascular accident. She presented with annular and serpiginous skin lesions on her back and arms that had ap...

  19. Use of Annular Closure Device (Barricaid®) for Preventing Lumbar Disc Reherniation: One-Year Results of Three Cases

    OpenAIRE

    Hahn, Bang Sang; Ji, Gyu Yeul; Moon, Bongju; Shin, Dong Ah; Ha, Yoon; Kim, Keung Nyun; Yoon, Do Heum

    2014-01-01

    Although lumbar discectomy is an effective treatment for lumbar disc herniation, complications exist, including postoperative disc height loss, facet joint degeneration, and recurrent disc herniation. To solve these problems, annular closure devices have been utilized in other countries, producing satisfactory results, but there has been no report of annular closure device use in our country. Here, we demonstrate the preliminary reports of Barricaid® insertion in 3 patients who underwent surg...

  20. An Annular Plate Model in Arbitrary-Lagrangian-Eulerian Description for the DLR FlexibleBodies Library

    OpenAIRE

    Heckmann, Andreas; Hartweg, Stefan; Kaiser, Ingo

    2011-01-01

    The bending deformation of rotating annular plates and the associated vibration behaviour is important in engineering applications which range from automotive or railway brake systems to discs that form essential components in turbomachinery. In order to extend the capabilities of the DLR FlexibleBodies library for such use cases, a new Modelica class has been implemented which is based on the analytical description of an annular Kirchhoff plate. In addition the so-called Arbitray Langra...

  1. Influence of the Southern Annular Mode on the sea ice-ocean system

    OpenAIRE

    W. Lefebvre; Goosse, H.; Timmermann, R.; Fichefet, T.

    2004-01-01

    [1] The global sea ice - ocean model ORCA2-LIM, driven by the NCEP/NCAR ( National Centers for Environmental Prediction-National Center for Atmospheric Research) reanalysis daily 2-m air temperatures and 10-m winds and by monthly climatologies for precipitation, cloud cover, and relative humidity, is used to investigate the impact of the Southern Annular Mode (SAM) on the Antarctic sea ice-ocean system. Our results suggest that the response of the circumpolar Southern Ocean consists of an ann...

  2. Slug-annular transition with particular reference to narrow rectangular ducts

    International Nuclear Information System (INIS)

    The transition from slug-flow to annular-flow in two-phase, gas-liquid mixtures is analyzed. A transition equation is derived which agrees well when compared with objective data determined from the disappearance of the low-void peak in the void fluctuation probability density in a rectangular duct. Application to other geometries is suggested and tabular recommendations given for determination of the drift flux coefficient, K, based on results in the literature

  3. Modification of transparent materials by tightly focused annular, radially and azimuthally polarized ultrafast laser beams

    OpenAIRE

    Zhang, J.(High Energy Physics Division, Argonne National Laboratory, Argonne, IL, USA); Gecevičius, M.; Beresna, M.; Kazansky, P. G.

    2013-01-01

    Recently, strong longitudinal electric fields have raised great interest in the laser fabrication, microscopy and optical data storage [1]. Here we demonstrate high quality cylindrically polarized annular beam produced by ultrafast laser written spatially variant polarization converter. We observed that nanogratings cannot be formed by strong longitudinal electric fields, created by a ring-shaped radially polarized beam. In addition, the stronger transverse electric field of azimuthal polariz...

  4. Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

    OpenAIRE

    Yan Teng; Jun Sun; Changhua Chen; Hao Shao

    2013-01-01

    This paper presents an approach that greatly enhances both the output power and the conversion efficiency of the coaxial relativistic backward wave oscillator (CRBWO) by using coaxial dual annular cathodes, which increases the diode current rather than the diode voltage. The reasons for the maladjustment of CRBWO under a high diode voltage are analyzed theoretically. It is found that by optimization of the diode structure, the shielding effect of the space charge of the outer beams on the inn...

  5. Direct and ozone-mediated forcing of the Southern Annular Mode by greenhouse gases

    OpenAIRE

    Morgenstern, Olaf; ZENG Guang; Dean, Sam M.; Joshi, Manoj; Abraham, N. Luke; Osprey, Annette

    2014-01-01

    We assess the roles of long-lived greenhouse gases and ozone depletion in driving meridional surface pressure gradients in the southern extratropics; these gradients are a defining feature of the Southern Annular Mode. Stratospheric ozone depletion is thought to have caused a strengthening of this mode during summer, with increasing long-lived greenhouse gases playing a secondary role. Using a coupled atmosphere-ocean chemistry-climate model, we show that there is cancelation between the dire...

  6. Vertical annular gas–liquid two-phase flow in large diameter pipes

    OpenAIRE

    Aliyu, A. M.

    2015-01-01

    Gas–liquid annular two phase flow in pipes is important in the oil and gas, nuclear and the process industries. It has been identified as one of the most frequently encountered flow regimes and many models (empirical and theoretical) for the film flow and droplet behaviour for example have been developed since the 1950s. However, the behaviour in large pipes (those with diameter greater than 100 mm) has not been fully explored. As a result, the two- phase flow characteristic...

  7. Three-dimensional free vibration analysis of carbon nanotube reinforced composites annular plates

    OpenAIRE

    Hakimeh Zali; Fatemeh Yazdian; Meisam Omidi

    2016-01-01

    The main objective of this research work was to investigate three-dimensional free vibration of thick annular plates which are composed of carbon nanotube (CNT) reinforced composites materials using the Chebyshev–Ritz method. In order to obtain precise results, a new form of the rule of mixtures including an exponential shape function, length efficiency parameter, orientation efficiency factor, and waviness parameter was applied for predicting the mechanical properties of CNT reinforced compo...

  8. Passive control of annular jet instabilities studied by Proper Orthogonal Decomposition

    OpenAIRE

    Danlos, Amélie; Rouland, Eric; PARANTHOEN, Pierre; PATTE-ROULAND, Béatrice

    2009-01-01

    Shear flows are complex turbulent flows which are widely used in the industrial domain. An annular jet is an example of these particular flows (used in burners, cooling processes, inlet valve in a combustion chamber, processing glass fibers...): an obstacle for the flow, placed in the center of a round nozzle creates two axisymmetric shear layers at the jet exit. These shear layers are significant for the organization and the evolution of the flow. This study talks about coherent structures d...

  9. Progress in analytical methods to predict and control azimuthal combustion instability modes in annular chambers

    OpenAIRE

    Bauerheim, Michaël; Nicoud, Franck; Poinsot, Thierry

    2016-01-01

    Longitudinal low-frequency thermoacoustic unstable modes in combustion chambers have been intensively studied experimentally, numerically, and theoretically, leading to significant progress in both understanding and controlling these acoustic modes. However, modern annular gas turbines may also exhibit azimuthal modes, which are much less studied and feature specific mode structures and dynamic behaviors, leading to more complex situations. Moreover, dealing with 10–20 burners mounted in the ...

  10. Grid Effects on LES Thermo-Acoustic Limit-Cycle of a Full Annular Aeronautical Engine

    Science.gov (United States)

    Wolf, Pierre; Gicquel, Laurent Y. M.; Staffelbach, Gabriel; Poinsot, Thierry

    Recent developments in large scale computer architectures allow Large Eddy Simulation (LES) to be considered for the prediction of turbulent reacting flows in geometries encountered in industry. To do so, various difficulties must be overcome and the first one is to ensure that proper meshes can be used for LES. Indeed, the quality of meshes is known to be a critical factor in LES of reacting flows. This issue becomes even more crucial when LES is used to compute large configurations such as full annular combustion chambers. Various analysis of mesh effects on LES results have been published before but all are limited to single-sector computational domains. However, real annular gas-turbine engines contain ten to twenty of such sectors and LES must also be used in such full chambers for the study of ignition or azimuthal thermo-acoustic interactions. Instabilities (mostly azimuthal modes involving the full annular geometry) remain a critical issue to aeronautical or power-generation industries and LES seems to be a promising path to properly apprehend such complex unsteady couplings. Based on these observations, mesh effects on LES in a full annular gas-turbine combustion chamber (including its casing) is studied here in the context of its azimuthal thermo-acoustic response. To do so, a fully compressible, multi-species reacting LES is used on two meshes yielding two fully unsteady turbulent reacting predictions of the same configuration. The two tetrahedra meshes contain respectively 38 and 93 millions cells. Limit-cycles as obtained by the two LES are gauged against each other for various flow quantities such as mean velocity profiles, flame position and temperature fields. The thermo-acoustic limit-cycles are observed to be relatively indepedent of the grid resolution which comforts the use of LES tools to provide insights and understanding of the mechanisms triggering the coupling between the system acoustic eigenmodes and combustion.

  11. Using LES to Study Reacting Flows and Instabilities in Annular Combustion Chambers

    OpenAIRE

    Wolf, Pierre; Balakrishnan, Ramesh; Staffelbach, Gabriel; Gicquel, Laurent Y.M.; Poinsot, Thierry

    2012-01-01

    Great prominence is put on the design of aeronautical gas turbines due to increasingly stringent regulations and the need to tackle rising fuel prices. This drive towards innovation has resulted sometimes in new concepts being prone to combustion instabilities. In the particular field of annular combustion chambers, these instabilities often take the form of azimuthal modes. To predict these modes, one must compute the full combustion chamber, which remained out of reach until very recently a...

  12. A New Approach to Designing the S-Shaped Annular Duct for Industrial Centrifugal Compressor

    OpenAIRE

    Ivan Yurko; German Bondarenko

    2014-01-01

    The authors propose an analytical method for designing the inlet annular duct for an industrial centrifugal compressor using high-order Bezier curves. Using the design of experiments (DOE) theory, the three-level full factorial design was developed for determination of influence of the dimensionless geometric parameters on the output criteria. Numerical research was carried out for determination of pressure loss coefficients and velocity swirl angles using the software system ANSYS CFX. Optim...

  13. Tricuspid annular plane systolic excursion and response to cardiac resynchronization therapy

    DEFF Research Database (Denmark)

    Kjaergaard, Jesper; Ghio, Stefano; St John Sutton, Martin;

    2011-01-01

    The aims of this study were to evaluate tricuspid annular plane systolic excursion (TAPSE) as a predictor of left ventricular (LV) reverse remodeling and clinical benefit of cardiac synchronization therapy (CRT) and to evaluate the effect of CRT on TAPSE in patients with mildly symptomatic systolic...... heart failure as a substudy of the REsyncronization reVErses Remodeling in Systolic left vEntricular dysfunction (REVERSE) trial....

  14. The thermophysical properties of gases determined using an annular acoustic resonator

    OpenAIRE

    Buxton, A. J.

    1997-01-01

    A novel annular acoustic resonator was constructed for measurements of the speed of sound in gases at pressures below 1 MPa. The resonator was designed to allow measurements of the speed and absorption of sound at low pressure in gases with large bulk viscosities. Measurements in propene, for which the speed of sound is known, served to characterise the geometry of the resonator and provide a test of the acoustic model for the system. A detailed description of the resonator whi...

  15. Acoustic and Large Eddy Simulation studies of azimuthal modes in annular combustion chambers

    OpenAIRE

    Wolf, Pierre; Staffelbach, Gabriel; Gicquel, Laurent Y.M.; Müller, Jens-Dominik; Poinsot, Thierry

    2012-01-01

    International audience The objectives of this paper are the description of azimuthal instability modes found in annular combus- tion chambers using two numerical tools: (1) Large Eddy Simulation (LES) methods and (2) acoustic solv- ers. These strong combustion instabilities are difficult to study experimentally and the present study is based on a LES of a full aeronautical combustion chamber. The LES exhibits a self-excited oscillation at the frequency of the first azimuthal eigenmode. The...

  16. Liquid Encapsulation in Parylene Microstructures Using Integrated Annular-Plate Stiction Valves

    OpenAIRE

    Gutierrez, Christian A.; Ellis Meng

    2011-01-01

    We report the design, fabrication and characterization of micromachined Parylene structures for self-sealing liquid encapsulation applications. Automatic sealing is enabled through the use of an integrated annular-plate stiction valve which greatly reduces device footprint over in-plane configurations. We achieve automatic wafer-level liquid entrapment without using adhesives or processing at elevated pressures or temperatures. The ability to track changes to the internal liquid volume throug...

  17. Missed Monteggia fracture in children: Is annular ligament reconstruction always required?

    Directory of Open Access Journals (Sweden)

    Bhaskar Atul

    2009-01-01

    Full Text Available Background: Chronic (neglected radiocapitellar joint dislocation is one of the feared complications of Monteggia fractures especially when associated with subtle fracture of the ulna bone. Many treatment strategies have been described to manage chronic Monteggia fracture and the need for annular ligament reconstruction is not always clear. The purpose of this study is to highlight the management of missed Monteggia fracture with particular emphasis on utility of annular ligament reconstruction by comparing the two groups of patients. Materials and Methods: In a prospective study 12 patients with mean age of 7.4 years, who presented with neglected Monteggia fractures, were studied. All children underwent open reduction of the radiocapitellar joint. Five children (Group A were treated with angulation-distraction osteotomy of ulna and annular ligament reconstruction and six cases (Group B required only angulation-distraction osteotomy of ulna without ligament reconstruction. In one case an open reduction of the radiocapitellar joint was sufficient to reduce the radial head and this was included in Group B. The gap between injury and presentation was from 3 months to 18 months (mean 9 months. Ten patients were classified as Bado I, and one each as Bado II and III respectively. We used the Kim′s criteria to score our results. Result: The mean follow-up period was 22 months. All ulna osteotomies healed uneventfully. The mean loss of pronation was 15 degree in Group A and 10 degree in Group B. Elbow flexion improved from the preoperative range and no child complained of pain, deformity and restriction of activity. The elbow score was excellent in 10 cases, and good in two cases. Conclusion: Distraction-angulation osteotomy of the ulna suffices in most cases of missed monteggia fracture and the need for annular ligament reconstruction is based on intraoperative findings of radial head instability.

  18. Severe mitral annular calcification in rheumatic heart disease: A rare presentation

    OpenAIRE

    Vijayvergiya, Rajesh; Vaiphei, Kim; Rana, Sandeep S

    2012-01-01

    Severe mitral annular calcification (MAC) is frequently seen in patients with advanced age and chronic kidney disease, but it is rare in rheumatic heart disease (RHD). We hereby report a case of 45-year-old female with chronic RHD, who had severe MAC and mitral regurgitation. Fluoroscopy revealed a “crown”-like severe calcification of the mitral annulus. Autopsy of the heart revealed a calcified posterior mitral annulus, fused commissures, and calcified nodules at the atrial aspect of the mit...

  19. Annular bone growth in phalanges of five Neotropical Harlequin Frogs (Anura: Bufonidae: Atelopus)

    OpenAIRE

    Erik Lindquist; Michael Redmer; Emily Brantner

    2012-01-01

    Skeletochronological studies were conducted on museum specimensrepresenting five species of the highly threatened Neotropical genus Atelopus (Bufonidae). We detected annular bone growth (expressed as lines of arrested growth [LAGs]) patterns in each species, and this might provide insight to understand demographic constituency infuture studies. In four of the five species under consideration, LAG counts in fore and hind limb bone occurred in a 1:1 ratio, indicating that bone growth was consis...

  20. Phased annular array transducers for omnidirectional guided wave mode control in isotropic plate like structures

    International Nuclear Information System (INIS)

    Ultrasonic guided waves are fast emerging as a reliable tool for continuous structural health monitoring. Their multi-modal nature along with their long range propagation characteristics offer several possibilities for interrogating structures. Transducers commonly used to generate guided waves in structures excite multiple modes at any frequency; their complex scattering and reflection from defects and boundaries often complicates the extraction of useful information. Often it is desirable to control the guided wave modes propagating in a structure to take advantage of their unique properties for different applications. Earlier attempts at guided wave mode control involved developing fixed wavelength linear and annular array transducers. Their only disadvantage is that the transducer is limited to a particular wavelength and a change in wavelength necessitates a change in the transducer. In this paper, we propose the development of an annular array transducer that can generate mode controlled omnidirectional guided waves by independently controlling the amplitude and phase of the array elements. A simplified actuator model that approximates the transducer loading on the structure to a constant pressure load under the array elements is assumed and an optimization problem is set up to compute the excitation voltage and phase of the elements. A five element annular array transducer is designed utilizing 1–3 type piezocomposite materials. The theoretical computations are experimentally verified on an aluminum plate like structure by exciting A0 and S0 guided wave modes. (paper)

  1. Investigations of mass transfer in annular gas-liquid flow in a microreactor

    Directory of Open Access Journals (Sweden)

    Sobieszuk Paweł

    2016-03-01

    Full Text Available The paper presents an investigation of mass transfer in gas-liquid annular flow in a microreactor. The microreactor had a meandered shape with a square cross-section of the channel (292×292 μm, hydraulic diameter 292 μm and 250 mm in length. The rate of CO2 absorption from the CO2/N2 mixture in NaOH (0.1 M, 0.2 M, 0.7 M, 1.0 M and 1.5 M water solutions was measured. Two velocities of gas flow and two velocities of liquid flow were used. In two cases a fully developed annular flow at the beginning of the channel was observed, whilst in two cases annular flow was formed only in about 2/3 of the microchannel length. Based on the measurements of CO2 absorption rate, the values of volumetric liquid - side mass transfer coefficients with the chemical reaction were determined. Then physical values of coefficients were found. Obtained results were discussed and their values were compared with the values predicted by literature correlations.

  2. Effects study on the thermal stresses in a LEU metal foil annular target

    International Nuclear Information System (INIS)

    The effects of fission gas pressure, uranium swelling and thermal contact conductance on the thermal–mechanical behavior of an annular target containing a low-enriched uranium foil (LEU) encapsulated in a nickel foil have been presented in this paper. The draw-plug assembly method is simulated to obtain the residual stresses, which are applied to the irradiation model as initial inputs, and the integrated assembly-irradiation process is simulated as an axisymmetric problem using the commercial finite element code Abaqus FEA. Parametric studies were performed on the LEU heat generation rate and the results indicate satisfactory irradiation performance of the annular target. The temperature and stress margins have been provided along with a discussion of the results. - Highlights: • Analyzed the thermal stresses in a low-enriched uranium foil based annular target. • Included fission gas, uranium swelling, and thermal contact conductance effects. • Worst case scenarios for temperature and stresses were found to be different. • Sensitivity studies on the foil heat generation rates were performed. • Temperature and stress were found to be within acceptable limits

  3. Annular multiphase flow behavior during deep water drilling and the effect of hydrate phase transition

    Institute of Scientific and Technical Information of China (English)

    Wang Zhiyuan; Sun Baojiang

    2009-01-01

    It is very important to understand the annular multiphase flow behavior and the effect of hydrate phase transition during deep water drilling. The basic hydrodynamic models, including mass, momentum, and energy conservation equations, were established for annular flow with gas hydrate phase transition during gas kick. The behavior of annular multiphase flow with hydrate phase transition was investigated by analyzing the hydrate-forming region, the gas fraction in the fluid flowing in the annulus, pit gain, bottom hole pressure, and shut-in casing pressure. The simulation shows that it is possible to move the hydrate-forming region away from sea floor by increasing the circulation rate. The decrease in gas volume fraction in the annulus due to hydrate formation reduces pit gain, which can delay the detection of well kick and increase the risk of hydrate plugging in lines. Caution is needed when a well is monitored for gas kick at a relatively low gas production rate, because the possibility of hydrate presence is much greater than that at a relatively high production rate. The shut-in casing pressure cannot reflect the gas kick due to hydrate formation, which increases with time.

  4. Progress in analytical methods to predict and control azimuthal combustion instability modes in annular chambers

    Science.gov (United States)

    Bauerheim, M.; Nicoud, F.; Poinsot, T.

    2016-02-01

    Longitudinal low-frequency thermoacoustic unstable modes in combustion chambers have been intensively studied experimentally, numerically, and theoretically, leading to significant progress in both understanding and controlling these acoustic modes. However, modern annular gas turbines may also exhibit azimuthal modes, which are much less studied and feature specific mode structures and dynamic behaviors, leading to more complex situations. Moreover, dealing with 10-20 burners mounted in the same chamber limits the use of high fidelity simulations or annular experiments to investigate these modes because of their complexity and costs. Consequently, for such circumferential acoustic modes, theoretical tools have been developed to uncover underlying phenomena controlling their stability, nature, and dynamics. This review presents recent progress in this field. First, Galerkin and network models are described with their pros and cons in both the temporal and frequency framework. Then, key features of such acoustic modes are unveiled, focusing on their specificities such as symmetry breaking, non-linear modal coupling, forcing by turbulence. Finally, recent works on uncertainty quantifications, guided by theoretical studies and applied to annular combustors, are presented. The objective is to provide a global view of theoretical research on azimuthal modes to highlight their complexities and potential.

  5. Flow-excited acoustic resonances of coaxial side-branches in an annular duct

    Science.gov (United States)

    Arthurs, D.; Ziada, S.

    2009-01-01

    This paper investigates the aeroacoustic response of an annular duct with closed coaxial side-branches, and examines the effect of several passive countermeasures on the resonance intensity. The investigated geometry is inspired by the design of the Roll-Posts in the Rolls-Royce LiftSystem® engine, which is currently being developed for the Lockheed Martin Joint Strike Fighter (JSF®) aircraft. The effects of design parameters, such as diameter ratio, branch length ratio and thickness of the annular flow on the frequency and resonance intensity of the first acoustic mode are studied experimentally. Numerical simulations of the acoustic mode shapes and frequencies are also performed. The annular flow has been found to excite several acoustic modes, the strongest in all cases being the first acoustic mode, which consists of a quarter wavelength along the length of each branch. The ratios of the branch length and diameter, with respect to the main duct diameter, have been found to have strong effects on the frequency of the acoustic modes.

  6. Dynamic Response of Rub Caused by a Shedding Annular Component Happening in a Steam Turbine

    Directory of Open Access Journals (Sweden)

    J. M. Chen

    2015-01-01

    Full Text Available Rub caused by a shedding annular component is a severe fault happening in a steam turbine, which could result in a long-term wearing effect on the shaft. The shafting abrasion defects shortened the service life and damaged the unit. To identify the fault in time, the dynamic response of rub caused by a shedding annular component was studied as follows: (I a rotor-bearing model was established based on the structural features of certain steam turbines; node-to-node contact constraint and penalty method were utilized to analyze the impact and friction; (II dynamic response of the rotor-bearing system and the shedding component was simulated with the development of rub after the component was dropping; (III fault features were extracted from the vibration near the bearing position by time-domain and frequency-domain analysis. The results indicate that the shedding annular component would not only rotate pivoting its axis but also revolve around the shaft after a period of time. Under the excitation of the contact force, the peak-peak vibration fluctuates greatly. The frequency spectrum contains two main components, that is, the working rotating frequency and revolving frequency. The same phenomenon was observed from the historical data in the field.

  7. Axicon-based annular laser trap for studies on sperm activity

    Science.gov (United States)

    Shao, Bing; Vinson, Jaclyn M.; Botvinick, Elliot L.; Esener, Sadik C.; Berns, Michael W.

    2005-08-01

    As a powerful and noninvasive tool, laser trapping has been widely applied for the confinement and physiological study of biological cells and organelles. Researchers have used the single spot laser trap to hold individual sperm and quantitatively evaluated the motile force generated by a sperm. Early studies revealed the relationship between sperm motility and swimming behavior and helped the investigations in medical aspects of sperm activity. As sperm chemotaxis draws more and more interest in fertilization research, the studies on sperm-egg communication may help to explain male or female infertility and provide exciting new approaches to contraception. However, single spot laser trapping can only be used to investigate an individual target, which has limits in efficiency and throughput. To study the chemotactic response of sperm to eggs and to characterize sperm motility, an annular laser trap with a diameter of several hundred microns is designed, simulated with ray tracing tool, and implemented. An axicon transforms the wavefront such that the laser beam is incident on the microscope objective from all directions while filling the back aperture completely for high efficiency trapping. A trapping experiment with microspheres is carried out to evaluate the system performance. The power requirement for annular sperm trapping is determined experimentally and compared with theoretical calculations. With a chemo-attractant located in the center and sperm approaching from all directions, the annular laser trapping could serve as a speed bump for sperm so that motility characterization and fertility sorting can be performed efficiently.

  8. Biochemical and immunohistochemical comparison of collagen in granuloma annulare and skin sarcoidosis.

    Science.gov (United States)

    Oikarinen, A; Kinnunen, T; Kallioinen, M

    1989-01-01

    Collagen was studied by biochemical and immunohistochemical means in 5 patients with granuloma annulare (GA) and 3 with cutaneous sarcoidosis (SA). The solubility of collagen from the lesional skin in acetic acid was higher than that of collagen from unaffected skin from both patients and control subjects. Collagen concentration in the skin lesions, measured in terms of hydroxyproline content, was reduced in 3 patients with granuloma annulare and one with sarcoidosis, but the ratio of type III/I collagen was unchanged vis-à-vis non-affected skin. The collagen concentration in non-affected skin of both GA and SA-patients was also lower than in controls. The most typical immunohistochemical finding was the association of type III procollagen and fibronectin with granulomas in the lesional skin of both GA and SA cases. The activity of prolyl hydroxylase, a key enzyme in collagen biosynthesis, was markedly increased in the lesional skin, indicating that collagen synthesis in vivo was also increased. Surprisingly, collagen synthesis was not increased in cell culture studies. This could be due to cell selection as observed previously in scleroderma. Another possibility could be that various mediators released in vivo from inflammatory cells activate fibroblasts. However, when cells are subcultivated, this effect is not maintained. In conclusion, marked changes in collagen could be observed in granuloma annulare and skin sarcoidosis, reflecting increased turnover of collagen in vivo.

  9. CFD Study of an Annular-Ducted Fan Lift System for VTOL Aircraft

    Directory of Open Access Journals (Sweden)

    Yun Jiang

    2015-09-01

    Full Text Available The present study aimed at assessing a novel annular-ducted fan lift system for VTOL aircraft through computational fluid dynamics (CFD simulations. The power and lift efficiency of the lift fan system in hover mode, the lift and drag in transition mode, the drag and flight speed of the aircraft in cruise mode and the pneumatic coupling of the tip turbine and jet exhaust were studied. The results show that the annular-ducted fan lift system can have higher lift efficiency compared to the rotor of the Apache helicopter; the smooth transition from vertical takeoff to cruise flight needs some extra forward thrust to overcome a low peak of drag; the aircraft with the lift fan system enclosed during cruise flight theoretically may fly faster than helicopters and tiltrotors based on aerodynamic drag prediction, due to the elimination of rotor drag and compressibility effects on the rotor blade tips; and pneumatic coupling of the tip turbine and jet exhaust of a 300 m/s velocity can provide enough moment to spin the lift fan. The CFD results provide insight for future experimental study of the annular-ducted lift fan VTOL aircraft.

  10. Asymmetric Vibration of Polar Orthotropic Annular Circular Plates of Quadratically Varying Thickness with Same Boundary Conditions

    Directory of Open Access Journals (Sweden)

    N. Bhardwaj

    2008-01-01

    Full Text Available In the present paper, asymmetric vibration of polar orthotropic annular circular plates of quadratically varying thickness resting on Winkler elastic foundation is studied by using boundary characteristic orthonormal polynomials in Rayleigh-Ritz method. Convergence of the results is tested and comparison is made with results already available in the existing literature. Numerical results for the first ten frequencies for various values of parameters describing width of annular plate, thickness profile, material orthotropy and foundation constant for all three possible combinations of clamped, simply supported and free edge conditions are shown and discussed. It is found that (a higher elastic property in circumferential direction leads to higher stiffness against lateral vibration; (b Lateral vibration characteristics of F-Fplates is more sensitive towards parametric changes in material orthotropy and foundation stiffness than C-C and S-Splates; (c Effect of quadratical thickness variation on fundamental frequency is more significant in cases of C-C and S-S plates than that of F-Fplates. Thickness profile which is convex relative to plate center-line tends to result in higher stiffness of annular plates against lateral vibration than the one which is concave and (d Fundamental mode of vibration of C-C and S-Splates is axisymmetrical while that of F-Fplates is asymmetrical.

  11. Concentration Measurements in a Cold Flow Model Annular Combustor Using Laser Induced Fluorescence

    Science.gov (United States)

    Morgan, Douglas C.

    1996-01-01

    A nonintrusive concentration measurement method is developed for determining the concentration distribution in a complex flow field. The measurement method consists of marking a liquid flow with a water soluble fluorescent dye. The dye is excited by a two dimensional sheet of laser light. The fluorescent intensity is shown to be proportional to the relative concentration level. The fluorescent field is recorded on a video cassette recorder through a video camera. The recorded images are analyzed with image processing hardware and software to obtain intensity levels. Mean and root mean square (rms) values are calculated from these intensity levels. The method is tested on a single round turbulent jet because previous concentration measurements have been made on this configuration by other investigators. The previous results were used to comparison to qualify the current method. These comparisons showed that this method provides satisfactory results. 'Me concentration measurement system was used to measure the concentrations in the complex flow field of a model gas turbine annular combustor. The model annular combustor consists of opposing primary jets and an annular jet which discharges perpendicular to the primary jets. The mixing between the different jet flows can be visualized from the calculated mean and rms profiles. Concentration field visualization images obtained from the processing provide further qualitative information about the flow field.

  12. A shaped annular beam tri-heterodyne confocal microscope with good anti-environmental interference capability

    Institute of Scientific and Technical Information of China (English)

    Zhao Wei-Qian; Feng Zheng-De; Qiu Li-Rong

    2007-01-01

    A shaped annular beam tri-heterodyne confocal microscope has been proposed to improve the anti-environmental interference capability and the resolution of a confocal microscope. It simultaneously detects far-, on-, and near-focus signals with given phase differences by dividing the measured light path of the confocal microscope into three sub-paths (signals). Pair-wise real-time heterodyne subtraction of the three signals is used to improve the anti-environmental interference capability, axial resolution, and linearity; and a shaped annular beam super-resolution technique is used to improve lateral resolution. Theoretical analyses and preliminary experiments indicate that an axial resolution of about 1 nm can be achieved with a shaped annular beam tri-heterodyne confocal microscope and its lateral resolution can be better than 0.2μm for λ= 632.8 nm, the numerical aperture of the lens of the microscope is NA = 0.85, and the normalized radius ε= 0.5.

  13. Shut-down margin study for the next generation VVER-1000 reactor including 13 x 13 hexagonal annular assemblies

    International Nuclear Information System (INIS)

    Highlights: → Shut-Down Margin (SDM) for the next generation annular fuel core of typical VVER-1000, 13 x 13 assemblies are calculated. → The MCNP-5 code is run for many cases with different core burn up at various core temperatures. → There is a substantial drop in SDM in the case of annular fuel for the same power level. → SDM for our proposed VVER-1000 annular pins is calculated for specific average fuel burn up values at the BOC, MOC, and EOC. - Abstract: Shut-Down Margin (SDM) for the next generation annular fuel core of typical VVER-1000, 13 x 13 assemblies are calculated as the main aim of the present research. We have applied the MCNP-5 code for many cases with different values of core burn up at various core temperatures, and therefore their corresponding coolant densities and boric acid concentrations. There is a substantial drop in SDM in the case of annular fuel for the same power level. Specifically, SDM for our proposed VVER-1000 annular pins is calculated when the average fuel burn up values at the BOC, MOC, and EOC are 0.531, 11.5, and 43 MW-days/kg-U, respectively.

  14. Laser Doppler velocimeter measurements and laser sheet imaging in an annular combustor model. M.S. Thesis, Final Report

    Science.gov (United States)

    Dwenger, Richard Dale

    1995-01-01

    An experimental study was conducted in annular combustor model to provide a better understanding of the flowfield. Combustor model configurations consisting of primary jets only, annular jets only, and a combination of annular and primary jets were investigated. The purpose of this research was to provide a better understanding of combustor flows and to provide a data base for comparison with computational models. The first part of this research used a laser Doppler velocimeter to measure mean velocity and statistically calculate root-mean-square velocity in two coordinate directions. From this data, one Reynolds shear stress component and a two-dimensional turbulent kinetic energy term was determined. Major features of the flowfield included recirculating flow, primary and annular jet interaction, and high turbulence. The most pronounced result from this data was the effect the primary jets had on the flowfield. The primary jets were seen to reduce flow asymmetries, create larger recirculation zones, and higher turbulence levels. The second part of this research used a technique called marker nephelometry to provide mean concentration values in the combustor. Results showed the flow to be very turbulent and unsteady. All configurations investigated were highly sensitive to alignment of the primary and annular jets in the model and inlet conditions. Any imbalance between primary jets or misalignment of the annular jets caused severe flow asymmetries.

  15. Free and friction-induced in-plane vibration of annular disks

    Science.gov (United States)

    Tzou, Kevin Ihwa

    1998-12-01

    Vibration and noise from disk brakes negatively affect passenger comfort and perceptions of quality in both the automotive and aircraft industries. With regulatory pressure for stopping distance and the emphasis on smaller and lighter components, new brakes not only have to meet design and performance requirements, but must minimize vibration as well. Although materials and geometries vary from application to application, disk brakes generally consist of rotating annular disk(s) subjected to in-plane friction which dissipates the kinetic energy of the vehicle. During this process, friction-induced vibration of the disk(s) occurs, resulting in brake noise. Although sound radiation results from a disk's out-of-plane vibration, substantial in-plane motions must also be present due to the in-plane friction. This in-plane vibration can play a key role in the dynamics of the friction interface and hence, in brake noise and vibration. In this thesis, experimental and analytical methods are used to study the in-plane vibration of annular disks with a view toward understanding disk brake vibration. The issues that are addressed and the major findings include: (1) Characterization of in-plane modes in annular disks. For automotive rotors and thick annular disks, in-plane modes of vibration have frequencies that are both comparable to low-order bending modes and within the measured range for brake squeal. Despite the large in-plane friction force provided by disk brakes, no existing model includes in-plane disk motion with in-plane friction. A three-dimensional vibration model is used to determine frequencies and mode shapes for an annular disk subject to two boundary conditions: all surfaces traction-free, and all free except for a constrained inner edge. (2) Identification of frequency clusters. Using experimental and analytical methods, the frequencies for families of in-plane modes are found to converge to a common value with increasing disk thickness to the limit of the

  16. Microwave generation enhancement of X-band CRBWO by use of coaxial dual annular cathodes

    Directory of Open Access Journals (Sweden)

    Yan Teng

    2013-07-01

    Full Text Available This paper presents an approach that greatly enhances both the output power and the conversion efficiency of the coaxial relativistic backward wave oscillator (CRBWO by using coaxial dual annular cathodes, which increases the diode current rather than the diode voltage. The reasons for the maladjustment of CRBWO under a high diode voltage are analyzed theoretically. It is found that by optimization of the diode structure, the shielding effect of the space charge of the outer beams on the inner cathode can be alleviated effectively and dual annular beams with the same kinetic energy can be explosively emitted in parallel. The coaxial reflector can enhance the conversion efficiency by improving the premodulation of the beams. The electron dump on the inner conductor ensures that the electron beams continue to provide kinetic energy to the microwave output until they vanish. Particle-in-cell (PIC simulation results show that generation can be enhanced up to an output power level of 3.63 GW and conversion efficiency of 45% at 8.97 GHz under a diode voltage of 659 kV and current of 12.27 kA. The conversion efficiency remains above 40% and the output frequency variation is less than 100 MHz over a voltage range of more than 150 kV. Also, the application of the coaxial dual annular cathodes means that the diode impedance is matched to that of the transmission line of the accelerators. This impedance matching can effectively eliminate power reflection at the diode, and thus increase the energy efficiency of the entire system.

  17. Interpreting the nature of Northern and Southern Annular Mode variability in CMIP5 Models

    Science.gov (United States)

    Schenzinger, V.; Osprey, S. M.

    2015-11-01

    Characteristic timescales for the Northern Annular Mode (NAM) and Southern Annular Mode (SAM) variability are diagnosed in historical simulations submitted to the Coupled Model Intercomparison Project Phase 5 (CMIP5) and are compared to the European Centre for Medium-Range Weather Forecasts ERA-Interim data. These timescales are calculated from geopotential height anomaly spectra using a recently developed method, where spectra are divided into low-frequency (Lorentzian) and high-frequency (exponential) parts to account for stochastic and chaotic behaviors, respectively. As found for reanalysis data, model spectra at high frequencies are consistent with low-order chaotic behavior, in contrast to an AR1 process at low frequencies. This places the characterization of the annular mode timescales in a more dynamical rather than purely stochastic context. The characteristic high-frequency timescales for the NAM and SAM derived from the model spectra at high frequencies are ˜5 days, independent of season, which is consistent with the timescales of ERA-Interim. In the low-frequency domain, however, models are slightly biased toward too long timescales, but within the error bars, a finding which is consistent with previous studies of CMIP3 models. For the SAM, low-frequency timescales in November, December, January, and February are overestimated in the models compared to ERA-Interim. In some models, the overestimation in the SAM austral summer timescale is partly due to interannual variability, which can inflate these timescales by up to ˜40% in the models but only accounts for about 5% in the ERA-Interim reanalysis.

  18. Auto-thermal combustion of lean gaseous fuels utilizing a recuperative annular double-layer catalytic converter

    Energy Technology Data Exchange (ETDEWEB)

    Budzianowski, W.M. [Wroclaw Univ. of Technology, Wroclaw (Poland). Div. of Chemical and Biochemical Processes, Faculty of Chemistry; Miller, R. [Wroclaw Univ. of Technology, Wroclaw (Poland). Inst. of Power Engineering and Fluid Mechanics, Faculty of Mechanical and Power Engineering

    2008-08-15

    This study investigated the auto-thermal combustion of lean gaseous fuels in a recuperative annular double-layer catalytic converter. An analysis of the stationary and transient performance of annular converters was presented. The feasibility of lean gaseous mixture combustion in auto-thermally operated recuperative annular double-layer catalytic converters was investigated. The aim of the study was to build a process model using mass, energy, and momentum differential balances. The model was used to study the static behaviour of a recuperative annular double layer converter; an annular converter operating in transient conditions; and energy accumulation and recuperation interactions. The effects of fuel temperature, external cooling, and fuel concentration were examined. Results of the study showed that a substantial reduction of the inter- and intra-phase resistances to mass and heat transfer was obtained. It was demonstrated that the use of a low value for the substrate's thermal conductivity accelerated ignition and retarded extinction. The recuperative converter was able to transfer short-time inlet disturbances of various parameters due to the energy accumulation and temporal reversed recuperation which counteracted destructive overheating of the catalysts. The stability analyses showed stable and unstable branches of solutions for the different parameters of the recuperative converter. 21 refs., 1 tab., 23 figs.

  19. The clinical application of "jetting suture" technique in annular repair under microendoscopic discectomy: A prospective single-cohort observational study.

    Science.gov (United States)

    Qi, Lei; Li, Mu; Si, Haipeng; Wang, Liang; Jiang, Yunpeng; Zhang, Shuai; Li, Le

    2016-08-01

    To introduce a new designed suture technique in annular repair under the microendoscopic discectomy (MED) surgery and to evaluate the clinical application of the technique in annular repair under MED with at least 2-year follow-up period.A new method of annular repair was designed and named "jetting suture" technique. Thirty consecutive patients with lumbar disc herniation were enrolled in the prospective single-cohort observational study. Patients were followed up at intervals of preoperative, postoperative 1 week, 3 months, 6 months, 1 year, and last follow-up. The clinical outcomes were evaluated by using Japanese Orthopaedic Association (JOA) score, Oswestry Disability Index, and modified Mcnab criteria.The procedure was successfully performed in all cases. No case required conversion to an open procedure. The mean age of patients was 36.6 years. Average blood loss was 45.8 ± 10.2 mL. The preoperative symptoms were alleviated significantly after surgery. All the standardized measures improved significantly at the last follow-up, including JOA score (10.1 to 26.6; P disc herniation was reported.The designed "jetting suture" technique in annular repair under MED can be performed safely and effectively. It could be a viable alternative to annular repair under lumbar discectomy. PMID:27495101

  20. The solution of a wedge disclination dipole interacting with an annular inclusion and the force acting on the disclination dipole

    Institute of Scientific and Technical Information of China (English)

    Song Hao-Peng; Fang Qi-Hong; Liu You-Wen

    2008-01-01

    The interaction between a wedge disclination dipole and an elastic annular inclusion is investigated. Utilizing the Muskhelishvili complex variable method, the explicit series form solutions of the complex potentials in the matrix and the inclusion region are derived. The image force acting on the disclination dipole centre is also calculated. The influence of the location of the disclination dipole and the thickness of the annular inclusion as well as the elastic dissimilarity of materials upon the equilibrium position of the disclination dipole is discussed in detail. The results show that a stable equilibrium point of the disclination dipole near the inclusion is found for certain combinations of material constant.Moreover, the force on the disclination dipole is strongly affected by the position of the disclination dipole and the thickness of annular inclusion. The repulsion force increases (or the attraction force reduces) with the increase of the thickness of the annular inclusion. An appropriate critical value of the thickness of the annular inclusion may be found to change the direction of the force on the disclination dipole. The present solutions include previous results as special cases.

  1. Silva. EDF two-phase 1D annular model of a CFB boiler furnace

    Energy Technology Data Exchange (ETDEWEB)

    Montat, D.; Fauquet, Ph. [Electricite de France (EDF), 78 - Chatou (France). Researckh and Development Div.; Lafanechere, L.; Bursi, J.M. [Electricite de France (EDF) (France). Construction Div.

    1997-01-01

    SILVA computer code is used for the modelling of the thermal-hydraulics and of the combustion of a coal-fired CFBC solid loop. In a first step, only the furnace is considered. The model is based on a 1D annular two phases description of the hydrodynamics. The model is based on particle mass balances and pressure drop calculations. A basic combustion model is incorporated into this model. The coal combustion is divided in two phases, the combustion of volatile matter and the heterogeneous combustion. The model has been developed within LEGO software and can be included into the global model of the solid loop developed by EDF. (author) 26 refs.

  2. Design of the annular binary filters with super-resolution based on the genetic algorithm

    Institute of Scientific and Technical Information of China (English)

    YU Qi-lei; LE Zi-chun; ZHU Hong-ying

    2006-01-01

    To improve the density of information storage,this paper introduces a kind of annular binary filters with super-resolution,Several of these filters have been designed based on the genetic algorithm,the simulations demonstrate that the transverse gain of the filters can reach the value of 1.37.Thus they can remarkably decrease the recording spot size,which is helpful to improve the density of information storage and to make the depth of focus longer,and therefore they can avoid the mistake caused by the small undulation of the optical disk in the process of recording/reading the information.

  3. Modeling Mist to Annular Flow Development in the Discharge of a Compressor

    OpenAIRE

    Wujek, Scott S.; Hrnjak, Predrag S.

    2012-01-01

    A model has been created to describe the development of flow leaving a compressor as it transitions from mist to annular flow. Flow parameters such as the drop size, drop speed, drop concentration, film thickness, and film velocity change as a function of length. Parameters such as refrigerant flow rates, oil in circulation ratios, and fluid properties are accounted for in these models. While some flow development work is found in the open literature for air-water or steam-water flows, little...

  4. Fuel distribution measurements in a model low NOx double annular combustor using laser induced fluorescence

    OpenAIRE

    Lockett, R. D.; Greenhalgh, D.A.

    2010-01-01

    Planar laser induced fluorescence (PLIF) was employed in a three sector, low NOx double annular combustor in order to characterise the combusting fuel spray. Naphthalene was employed as a fluorescent agent in odourless kerosene in order to determine the behavior of the light fractions in the fuel vapour, and the light to medium fractions in the fuel spray, while 2,5 di-phenyl oxizol (ppo) was employed to determine the behavior of the heavy fractions in the fuel spray. Counter-swirl air blast ...

  5. Stability analysis of thermo-acoustic nonlinear eigenproblems in annular combustors. Part II. Uncertainty quantification

    CERN Document Server

    Magri, Luca; Nicoud, Franck; Juniper, Matthew

    2016-01-01

    Monte Carlo and Active Subspace Identification methods are combined with first- and second-order adjoint sensitivities to perform (forward) uncertainty quantification analysis of the thermo-acoustic stability of two annular combustor configurations. This method is applied to evaluate the risk factor, i.e., the probability for the system to be unstable. It is shown that the adjoint approach reduces the number of nonlinear-eigenproblem calculations by up to $\\sim\\mathcal{O}(M)$, as many as the Monte Carlo samples.

  6. Study on Friction Factor of Developing and Developed Laminar FLow in Annular-Sector Ducts

    Institute of Scientific and Technical Information of China (English)

    1995-01-01

    The pressure drops of laminar developing and developed flow in annular-sector ducts with small roud corner have been investigated experimentally.Numerical simulation has been performed to study the effect of the small round corner on the friction factor in the developed region.It has been found that with the increase in corner radius,the value of f Re decreases,In the range of rc/ro from 0.031to 0.12,the decrease in fRe varies from 0.048%to 0.1% for the fie apex angle computed.

  7. An annular gas seal analysis using empirical entrance and exit region friction factors

    Science.gov (United States)

    Elrod, D. A.; Childs, D. W.; Nelson, C. C.

    1990-01-01

    Wall shear stress results from stationary-rotor flow tests of five annular gas seals are used to develop entrance and exit region friction factor models. The friction factor models are used in a bulk-flow seal analysis which predicts leakage and rotor-dynamic coefficients. The predictions of the analysis are compared to experimental results and to the predictions of Nelson's analysis (1985). The comparisons are for smooth-rotor seals with smooth and honeycomb-stators. The present analysis predicts the destabilizing cross-coupled stiffness of a seal better than Nelson's analysis. Both analyses predict direct damping well and direct stiffness poorly.

  8. Fourier-Bessel Field Calculation and Tuning of a CW Annular Array

    DEFF Research Database (Denmark)

    Fox, Paul D.; Cheng, Jiqi; Lu, Jian-yu

    2002-01-01

    A 1-D Fourier-Bessel series method for computing and tuning the linear lossless field of flat continuous wave (CW) annular arrays is given and discussed with both numerical simulation and experimental verification. The technique provides a new method for modelling and manipulating the propagated...... field by linking the quantized surface pressure profile to a set of limited diffraction Bessel beams propagating into the medium. In the limit, these become a known set of nondiffracting Bessel beams satisfying the lossless linear wave equation, which allow us to derive a linear matrix formulation for...

  9. Generation of Electron Bessel Beams with Nondiffractive Spreading by a Nanofabricated Annular Slit

    Science.gov (United States)

    Saitoh, Koh; Hirakawa, Kazuma; Nambu, Hiroki; Tanaka, Nobuo; Uchida, Masaya

    2016-04-01

    The shaping of a wavefront of free electrons has been experimentally realized very recently. We report the generation of an electron Bessel beam using a nanofabricated annular slit. We directly observe that electron Bessel beams propagate while maintaining a narrow beam width over a long propagation distance. In addition, we experimentally verify the self-healing property of these electron beams, which can reconstruct their shape after passing an obstacle. The experimental results are compared with simulation results of the propagation including a hexagonal slit. The present technique of electron Bessel beam generation can be used to develop a novel electron-beam-shaping, an atomic manipulation technique, and a new electron microscopy.

  10. Experimental investigation on Heat Transfer Performance of Annular Flow Path Heat Pipe

    Energy Technology Data Exchange (ETDEWEB)

    Kim, In Guk; Kim, Kyung Mo; Jeong, Yeong Shin; Bang, In Cheol [UNIST, Ulsan (Korea, Republic of)

    2015-05-15

    Mochizuki et al. was suggested the passive cooling system to spent nuclear fuel pool. Detail analysis of various heat pipe design cases was studied to determine the heat pipes cooling performance. Wang et al. suggested the concept PRHRS of MSR using sodium heat pipes, and the transient performance of high temperature sodium heat pipe was numerically simulated in the case of MSR accident. The meltdown at the Fukushima Daiichi nuclear power plants alarmed to the dangers of station blackout (SBO) accident. After the SBO accident, passive decay heat removal systems have been investigated to prevent the severe accidents. Mochizuki et al. suggested the heat pipes cooling system using loop heat pipes for decay heat removal cooling and analysis of heat pipe thermal resistance for boiling water reactor (BWR). The decay heat removal systems for pressurized water reactor (PWR) were suggested using natural convection mechanisms and modification of PWR design. Our group suggested the concept of a hybrid heat pipe with control rod as Passive IN-core Cooling System (PINCs) for decay heat removal for advanced nuclear power plant. Hybrid heat pipe is the combination of the heat pipe and control rod. In the present research, the main objective is to investigate the effect of the inner structure to the heat transfer performance of heat pipe containing neutron absorber material, B{sub 4}C. The main objective is to investigate the effect of the inner structure in heat pipe to the heat transfer performance with annular flow path. ABS pellet was used instead of B{sub 4}C pellet as cylindrical structures. The thermal performances of each heat pipes were measured experimentally. Among them, concentric heat pipe showed the best performance compared with others. 1. Annular evaporation section heat pipe and annular flow path heat pipe showed heat transfer degradation. 2. AHP also had annular vapor space and contact cooling surface per unit volume of vapor was increased. Heat transfer

  11. Dimension-optimizing design method for annular-type cooling channel of thrust chamber

    Science.gov (United States)

    Chen, Jie

    1995-05-01

    The new-generation liquid oxygen/hydrocarbon propellant liquid fuel rocket engine will use a high-pressure combustion chamber arrangement. In this case, cooling the thrust chamber becomes a key technical problem. The article presents a design scheme for the geometric-dimension optimization of annular-type regenerative cooling channels. The aim of the optimization is minimum pressure losses as coolant passes through the cooling channel. As shown in typical computations and experiments, application of this optimizing design method can reduce 50 percent of pressure losses. In other words, the optimization design is advantageous in solving the cooling problem in high-pressure thrust chambers.

  12. Ceramic coating effect on liner metal temperatures of film-cooled annular combustor

    Science.gov (United States)

    Claus, R. W.; Wear, J. D.; Liebert, C. H.

    1979-01-01

    An experimental and analytical investigation was conducted to determine the effect of a ceramic coating on the average metal temperatures of full annular, film cooled combustion chamber liner. The investigation was conducted at pressures from 0.50 to 0.062. At all test conditions, experimental results indicate that application of a ceramic coating will result in significantly lower wall temperatures. In a simplified heat transfer analysis, agreement between experimental and calculated liner temperatures was achieved. Simulated spalling of a small portion of the ceramic coating resulted in only small increases in liner temperature because of the thermal conduction of heat from the hotter, uncoated liner metal.

  13. Characterization of the Annular Core Research Reactor (ACRR) Neutron Radiography System Imaging Plane

    OpenAIRE

    Kaiser Krista; Chantel Nowlen K.; Russell DePriest K.

    2016-01-01

    The Annular Core Research Reactor (ACRR) at Sandia National Laboratories (SNL) is an epithermal pool-type research reactor licensed up to a thermal power of 2.4 MW. The ACRR facility has a neutron radiography facility that is used for imaging a wide range of items including reactor fuel and neutron generators. The ACRR neutron radiography system has four apertures (65:1, 125:1, 250:1, and 500:1) available to experimenters. The neutron flux and spectrum as well as the gamma dose rate were char...

  14. ANNULAR RING SLOT MSA AND ITS PERFORMANCE BY INTRODUCING GEOMETRY ON GROUND PLANE

    Directory of Open Access Journals (Sweden)

    PADAM SINGH

    2010-09-01

    Full Text Available This paper presents a rigorous comparative study of the effect of the geometry on ground plane on radiation characteristics of an annular ring slot antenna and found that there is great improvement by introducing the structure on ground plane .In this paper a U-shaped ground plane geometry [1] is considered. Simulation results show a variation in resonance frequency from 2.184 GHz to 1.688 GHz and a meaningful increase in bandwidth from 2MHz to 59 MHz. The simulations are carried out using Zeland IE3D software .

  15. Bose–Einstein condensates in concentrically coupled annular traps with spin–orbit coupling and rotation

    International Nuclear Information System (INIS)

    We investigate Bose–Einstein condensates in concentrically coupled annular traps with spin–orbit coupling and rotation. The ground state wave functions are computed by minimizing the Gross–Pitaevskii energy functional, and the combined effects of system's parameters, especially the spin–orbit coupling and rotating, are investigated. The results show that for a finite fixed spin–orbit coupling, with increasing the angular frequency of rotation, the system is always in phase coexistence. Moreover, phase transitions between different ground state phases can be induced not only by spin–orbit coupling, but also rotation, which resembles very much the one where the s-wave interactions are varied.

  16. Liquid Encapsulation in Parylene Microstructures Using Integrated Annular-Plate Stiction Valves

    Directory of Open Access Journals (Sweden)

    Christian A. Gutierrez

    2011-09-01

    Full Text Available We report the design, fabrication and characterization of micromachined Parylene structures for self-sealing liquid encapsulation applications. Automatic sealing is enabled through the use of an integrated annular-plate stiction valve which greatly reduces device footprint over in-plane configurations. We achieve automatic wafer-level liquid entrapment without using adhesives or processing at elevated pressures or temperatures. The ability to track changes to the internal liquid volume through the use of electrochemical impedance measurements is also presented.

  17. Recent advances of annular centrifugal extractor for hot test of nuclear waste partitioning process

    Institute of Scientific and Technical Information of China (English)

    HeXiang-Ming; YanYu-Shun; 等

    1998-01-01

    Advances are being made in the design of the annular centrifugal extractor fornuclear fuel reprocessing extraction process studies.The extractors have been built and tested.Twelve stages of this extractor and 50 stages are used toimplement the TRPO process for the cleanup ofcommercial and defense nuclear waste liquids,respectively.Following advances are available:(1) simple way of assembly and disassembly between rotor part and housing part of extractor,ease of manipulator operation;(2)automatic sampling from housing of extractor in hot cell;(3) compact multi-stage housing system;(4) easy interstage link;(5) computer data acquisition and monitoring system of speed.

  18. Optimized Annular Triode Ion Pump for Experimental Areas in the LHC

    CERN Document Server

    Knaster, J R; Chatelaine, A; Flakowski, D; Girard, C; Ivaldi, S; Laurent, Jean Michel; Monteiro, I; Rossi, A; Veness, R J M

    2003-01-01

    The LHC will be the world next generation accelerator to be operational in 2007 at CERN. The UHV requirements force the installation of ion pumps in the experimental areas of ATLAS. Due to the unacceptable particle background that standards ion pumps may generate, a reduction in the amount of material constitutive of the pump body is required. Hence, an stainless steel 0.8 mm thick body annular triode ion pump has been designed. A pumping speed of ~ 20 l/s at 10-9 mbar is provided by 15 pumping elements. Finite elements analysis and destructive tests have been performed in its design. Final vacuum tests results are shown.

  19. Self-organized Hydrodynamics in an Annular Domain: Modal Analysis and Nonlinear Effects

    OpenAIRE

    Degond, Pierre; Yu, Hui

    2014-01-01

    The Self-Organized Hydrodynamics model of collective behavior is studied on an annular domain. A modal analysis of the linearized model around a perfectly polarized steady-state is conducted. It shows that the model has only pure imaginary modes in countable number and is hence stable. Numerical computations of the low-order modes are provided. The fully non-linear model is numerically solved and nonlinear mode-coupling is then analyzed. Finally, the efficiency of the modal decomposition to a...

  20. Experimental study on large diameter drilling in hard rock annular coring

    Institute of Scientific and Technical Information of China (English)

    Yinzhu WU; Guochun YANG; Wenchen WANG

    2008-01-01

    Based on analyzing method of large diameter hard rock drilling at home and abroad, the authors proposed a set of drilling of large diameter hard rock annular coring in low energy consumption, low cost and high efficiency. The prototype of drilling tools was designed and was made. The experimental result of the prototype indicates that this plan and technology are feasible and reach the anticipated object of design. A set of drilling tools has been offered for the constructs of large diameter hard rock coring.

  1. Annular bone growth in phalanges of five Neotropical Harlequin Frogs (Anura: Bufonidae: Atelopus

    Directory of Open Access Journals (Sweden)

    Erik Lindquist

    2012-12-01

    Full Text Available Skeletochronological studies were conducted on museum specimensrepresenting five species of the highly threatened Neotropical genus Atelopus (Bufonidae. We detected annular bone growth (expressed as lines of arrested growth [LAGs] patterns in each species, and this might provide insight to understand demographic constituency infuture studies. In four of the five species under consideration, LAG counts in fore and hind limb bone occurred in a 1:1 ratio, indicating that bone growth was consistent within each individual. The use of skeletochronology in understanding historic and existing populations of Atelopus might assist in situ and ex situ population managers in making informed strategic conservation plans.

  2. Annular cylinders experimental programme containing plutonium solutions at different 240Pu contents

    International Nuclear Information System (INIS)

    From 1963 to 1976, 730 critical experiments dealing with annular cylinders containing plutonium nitrate solutions were conducted on Valduc critical facility, called 'Apparatus B'. They aimed at validating critical configurations encountered in the fuel cycle, especially in storage and also at validating the 240Pu cross-sections in thermal neutron spectrum. It is to be noticed that these experiments validate criticality codes either in configurations with reactor-grade plutonium coming from the reprocessing cycle or with weapon-grade plutonium coming from the decommissioning of nuclear weapons. (authors)

  3. Fully developed laminar mixed convection through a vertical annular duct filled with porous media

    Energy Technology Data Exchange (ETDEWEB)

    Kou, H.S.; Huang, D.K. [Tatung Inst. of Tech., Taipei (Taiwan, Province of China). Dept. of Mechanical Engineering

    1997-01-01

    The fully developed laminar mixed convection through a vertical annular duct embedded in a porous medium has been solved by using the non-Darcian flow model, where thermal boundary conditions on inner and outer walls are prescribed as isothermal-isothermal, isothermal-isoflux, and isoflux-isothermal, separately. The analytical solution has been derived to obtain velocity and temperature profiles, mass flow rate, wall friction factor and heat carried out by fluid. Finally, the parametric zones for flow characteristics of velocity distribution with the upward or downward flow are demonstrated.

  4. Laser anemometer measurements in an annular cascade of core turbine vanes and comparison with theory

    Science.gov (United States)

    Goldman, L. J.; Seashultz, R. G.

    1982-01-01

    Laser measurements were made in an annular cascade of stator vanes operating at an exit critical velocity ratio of 0.78. Velocity and flow angles in the blade to blade plane were obtained at every 10 percent of axial chord within the passage and at 1/2 axial chord downstream of the vanes for radial positions near the hub, mean and tip. Results are presented in both plot and tabulated form and are compared with calculations from an inviscid, quasi three dimensional computer program. The experimental measurements generally agreed well with these theoretical calculations, an indication of the usefulness of this analytic approach.

  5. Stem Cell Networks

    OpenAIRE

    Werner, Eric

    2016-01-01

    We present a general computational theory of stem cell networks and their developmental dynamics. Stem cell networks are special cases of developmental control networks. Our theory generates a natural classification of all possible stem cell networks based on their network architecture. Each stem cell network has a unique topology and semantics and developmental dynamics that result in distinct phenotypes. We show that the ideal growth dynamics of multicellular systems generated by stem cell ...

  6. Limbal stem cell transplantation

    OpenAIRE

    Fernandes Merle; Sangwan Virender; Rao Srinivas; Basti Surendra; Sridhar Mittanamalli; Bansal Aashish; Dua Harminder

    2004-01-01

    The past two decades have witnessed remarkable progress in limbal stem cell transplantation. In addition to harvesting stem cells from a cadaver or a live related donor, it is now possible to cultivate limbal stem cells in vitro and then transplant them onto the recipient bed. A clear understanding of the basic disease pathology and a correct assessment of the extent of stem cell deficiency are essential. A holistic approach towards management of limbal stem cell deficiency is needed. This ...

  7. Fish Stem Cell Cultures

    OpenAIRE

    Ni Hong, Zhendong Li, Yunhan Hong

    2011-01-01

    Stem cells have the potential for self-renewal and differentiation. First stem cell cultures were derived 30 years ago from early developing mouse embryos. These are pluripotent embryonic stem (ES) cells. Efforts towards ES cell derivation have been attempted in other mammalian and non-mammalian species. Work with stem cell culture in fish started 20 years ago. Laboratory fish species, in particular zebrafish and medaka, have been the focus of research towards stem cell cultures. Medaka is th...

  8. Stem Cell Separation Technologies

    OpenAIRE

    Zhu, Beili; Murthy, Shashi K

    2013-01-01

    Stem cell therapy and translational stem cell research require large-scale supply of stem cells at high purity and viability, thus leading to the development of stem cell separation technologies. This review covers key technologies being applied to stem cell separation, and also highlights exciting new approaches in this field. First, we will cover conventional separation methods that are commercially available and have been widely adapted. These methods include Fluorescence-activated cell so...

  9. Granuloma Annulare

    Science.gov (United States)

    ... Other oral medications such as potassium iodide, dapsone, nicotinamide, pentoxifylline, hydroxychloroquine, or cyclosporine Trusted Links MedlinePlus: Skin Conditions References Bolognia, Jean L., ed. Dermatology , pp. ...

  10. STEM investigation of exsolution lamellae and "c" reflections in Ca-rich dolomite from the Platteville Formation, western Wisconsin

    CERN Document Server

    Shen, Zhizhang; Brown, Philip E; Xu, Huifang

    2016-01-01

    Dolomite crystals in partially dolomitized limestone from the Platteville Formation are both compositionally and microstructurally heterogeneous. A single dolomite crystal usually contains three phases: the host Ca-rich dolomite [Ca1.14Mg0.86(CO3)2], an Fe-bearing dolomite [Ca1.06Mg0.80Fe0.14(CO3)2], and calcite inclusions. These three phases show similar orientations. The Ca-rich dolomite exhibits modulated microstructures with wavelength ranging from 7 to 30 nm. The modulated microstructures are not evident in Fe-bearing dolomite. Modulations in the Ca-rich dolomite have three predominant orientation ranges in the studied sample: from (205) to (104), from (001) to (-101), and ~(110), which are consistent with previous studies. Bright-field (BF) and high-angle annular dark-field (HAADF) images confirm that these modulations are due to chemical variation rather than strain or diffraction contrast. The Ca-rich lamellae are Mg-rich calcite with compositions ranging from Ca0.85Mg0.15CO3 to Ca0.70Mg0.30CO3. The o...

  11. Modeling of Focused Acoustic Field of a Concave Multi-annular Phased Array Using Spheroidal Beam Equation

    Institute of Scientific and Technical Information of China (English)

    余立立; 寿文德; 惠春

    2012-01-01

    A theoretical model of focused acoustic field for a multi-annular phased array on concave spherical surface is proposed. In this model, the source boundary conditions of the spheroidal beam equation (SBE) for multi-annular phased elements are studied. Acoustic field calculated by the dynamic focusing model of SBE is compared with numerical results of the O'Neil and Khokhlov-Zabolotskaya-Kuznetsov (KZK) model, respectively. Axia/dynamic focusing and the harmonic effects are presented. The results demonstrate that the dynamic focusing model of SBE is good valid for a concave multi-annular phased array with a large aperture angle in the linear or nonlinear field.

  12. Numerical Analysis of General Trends in Single-Phase Natural Circulation in a 2D-Annular Loop

    Directory of Open Access Journals (Sweden)

    Gilles Desrayaud

    2008-01-01

    Full Text Available The aim of this paper is to address fluid flow behavior of natural circulation in a 2D-annular loop filled with water. A two-dimensional, numerical analysis of natural convection in a 2D-annular closed-loop thermosyphon has been performed for various radius ratios from 1.2 to 2.0, the loop being heated at a constant flux over the bottom half and cooled at a constant temperature over the top half. It has been numerically shown that natural convection in a 2D-annular closed-loop thermosyphon is capable of showing pseudoconductive regime at pitchfork bifurcation, stationary convective regimes without and with recirculating regions occurring at the entrance of the exchangers, oscillatory convection at Hopf bifurcation and Lorenz-like chaotic flow. The complexity of the dynamic properties experimentally encountered in toroidal or rectangular loops is thus also found here.

  13. Internal combustion engine with a central crankshaft and integral tandem annular pistons

    Science.gov (United States)

    Esparbes, Bernard

    1993-08-01

    An internal combustion engine with tandem annular pistons and a central crankshaft is disclosed, based on that found in British patent 11027 of 11 May 1914. The piston block formed by the two pistons presents, at each axial extremity, a double axial skirt fitted with an outer crown forming the head of the piston as such, and an inner crown forming an inlet pump with a holding chamber radially located at the inside of the corresponding annular cylinder, in which the piston head delimits a combustion chamber. Radial fingers, crossing axial openings of the crankcase and radial holes of the piston block, have their inner radial ends engaged within wavy sinusoidal peripheral slots arranged in a bulging central portion of the central crankshaft set into rotation by alternating axial movements of the piston block. The admission of fuel or combustion sustaining gas is ensured axially by the extremities, valves, and openings in the end plates closing the holding chambers in which the inner crowns slide, fitted with valves to act as an inlet pump. The invention is particularly applicable to aircraft engines in view of the ease in which the shaft rotation can be adapted to such a use.

  14. 3-D vibration analysis of annular sector plates using the Chebyshev-Ritz method

    Science.gov (United States)

    Zhou, D.; Lo, S. H.; Cheung, Y. K.

    2009-02-01

    The three-dimensional free vibration of annular sector plates with various boundary conditions is studied by means of the Chebyshev-Ritz method. The analysis is based on the three-dimensional small strain linear elasticity theory. The product of Chebyshev polynomials satisfying the necessary boundary conditions is selected as admissible functions in such a way that the governing eigenvalue equation can be conveniently derived through an optimization process by the Ritz method. The boundary functions guarantee the satisfaction of the geometric boundary conditions of the plates and the Chebyshev polynomials provide the robustness for numerical calculation. The present study provides a full vibration spectrum for the thick annular sector plates, which cannot be given by the two-dimensional (2-D) theories such as the Mindlin theory. Comprehensive numerical results with high accuracy are systematically produced, which can be used as benchmark to evaluate other numerical methods. The effect of radius ratio, thickness ratio and sector angle on natural frequencies of the plates with a sector angle from 120° to 360° is discussed in detail. The three-dimensional vibration solutions for plates with a re-entrant sector angle (larger than 180°) and shallow helicoidal shells (sector angle larger than 360°) with a small helix angle are presented for the first time.

  15. Internal (Annular) and Compressible External (Flat Plate) Turbulent Flow Heat Transfer Correlations.

    Energy Technology Data Exchange (ETDEWEB)

    Dechant, Lawrence [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States); Smith, Justin [Sandia National Lab. (SNL-NM), Albuquerque, NM (United States)

    2016-01-01

    Here we provide a discussion regarding the applicability of a family of traditional heat transfer correlation based models for several (unit level) heat transfer problems associated with flight heat transfer estimates and internal flow heat transfer associated with an experimental simulation design (Dobranich 2014). Variability between semi-empirical free-flight models suggests relative differences for heat transfer coefficients on the order of 10%, while the internal annular flow behavior is larger with differences on the order of 20%. We emphasize that these expressions are strictly valid only for the geometries they have been derived for e.g. the fully developed annular flow or simple external flow problems. Though, the application of flat plate skin friction estimate to cylindrical bodies is a traditional procedure to estimate skin friction and heat transfer, an over-prediction bias is often observed using these approximations for missile type bodies. As a correction for this over-estimate trend, we discuss a simple scaling reduction factor for flat plate turbulent skin friction and heat transfer solutions (correlations) applied to blunt bodies of revolution at zero angle of attack. The method estimates the ratio between axisymmetric and 2-d stagnation point heat transfer skin friction and Stanton number solution expressions for sub-turbulent Reynolds numbers %3C1x10 4 . This factor is assumed to also directly influence the flat plate results applied to the cylindrical portion of the flow and the flat plate correlations are modified by

  16. Can Eddy Forcing be Responsible for the Spatial Structure of the Northern Hemisphere Annular Mode?

    Institute of Scientific and Technical Information of China (English)

    ZHAO Nan; LI Yan; SHEN Xinyong

    2010-01-01

    In order to study the origin of the spatial structure of the Northern Hemisphere Annular Mode (NAM),a linear stochastic model is constructed empirically from the output of a GCM run.Optimal stochastic forcing in terms of the maximum variance contribution,which may be potentially related to the maintenance of the NAM,is investigated.Theoretical analysis on the dominant non-modal response to the stochastic forcing shows that this dominance is jointly decided by the properties of forcing and the non-modal growth (decay).The results of computation demonstrate that the eddy forcing corresponding to the instantaneous rapid growth of the NAM,which is indicated by the instantaneous stochastic optimum,has a roughly similar but significantly different annular structure like that of the NAM.On the other hand,the eddy forcing corresponding to the stationary variance of the NAM,which is indicated by the asymptotic stochastic optimum,has a totally different structure from that of the NAM.These results,together with our general discussion on the relationship between the spatial structure of forcing and response,suggest that one should be careful when explaining the spatial structure of the NAM by that of the eddy forcing.

  17. Massively parallel LES of azimuthal thermo-acoustic instabilities in annular gas turbines

    Science.gov (United States)

    Wolf, Pierre; Staffelbach, Gabriel; Gicquel, Laurent; Poinsot, Thierry

    2009-07-01

    Most of the energy produced worldwide comes from the combustion of fossil fuels. In the context of global climate changes and dramatically decreasing resources, there is a critical need for optimizing the process of burning, especially in the field of gas turbines. Unfortunately, new designs for efficient combustion are prone to destructive thermo-acoustic instabilities. Large Eddy Simulation (LES) is a promising tool to predict turbulent reacting flows in complex industrial configurations and explore the mechanisms triggering the coupling between acoustics and combustion. In the particular field of annular combustion chambers, these instabilities usually take the form of azimuthal modes. To predict these modes, one must compute the full combustion chamber comprising all sectors, which remained out of reach until very recently and the development of massively parallel computers. A fully compressible, multi-species reactive Navier-Stokes solver is used on up to 4096 BlueGene/P CPUs for two designs of a full annular helicopter chamber. Results show evidence of self-established azimuthal modes for the two cases but with different energy containing limit-cycles. Mesh dependency is checked with grids comprising 38 and 93 million tetrahedra. The fact that the two grid predictions yield similar flow topologies and limit-cycles enforces the ability of LES to discriminate design changes.

  18. Massively parallel LES of azimuthal thermo-acoustic instabilities in annular gas turbines

    International Nuclear Information System (INIS)

    Most of the energy produced worldwide comes from the combustion of fossil fuels. In the context of global climate changes and dramatically decreasing resources, there is a critical need for optimizing the process of burning, especially in the field of gas turbines. Unfortunately, new designs for efficient combustion are prone to destructive thermo-acoustic instabilities. Large Eddy Simulation (LES) is a promising tool to predict turbulent reacting flows in complex industrial configurations and explore the mechanisms triggering the coupling between acoustics and combustion. In the particular field of annular combustion chambers, these instabilities usually take the form of azimuthal modes. To predict these modes, one must compute the full combustion chamber comprising all sectors, which remained out of reach until very recently and the development of massively parallel computers. A fully compressible, multi-species reactive Navier-Stokes solver is used on up to 4096 BlueGene/P CPUs for two designs of a full annular helicopter chamber. Results show evidence of self-established azimuthal modes for the two cases but with different energy containing limit-cycles. Mesh dependency is checked with grids comprising 38 and 93 million tetrahedra. The fact that the two grid predictions yield similar flow topologies and limit-cycles enforces the ability of LES to discriminate design changes.

  19. Annular precision linear shaped charge flight termination system for the ODES program

    Energy Technology Data Exchange (ETDEWEB)

    Vigil, M.G.; Marchi, D.L.

    1994-06-01

    The work for the development of an Annular Precision Linear Shaped Charge (APLSC) Flight Termination System (FTS) for the Operation and Deployment Experiment Simulator (ODES) program is discussed and presented in this report. The Precision Linear Shaped Charge (PLSC) concept was recently developed at Sandia. The APLSC component is designed to produce a copper jet to cut four inch diameter holes in each of two spherical tanks, one containing fuel and the other an oxidizer that are hyperbolic when mixed, to terminate the ODES vehicle flight if necessary. The FTS includes two detonators, six Mild Detonating Fuse (MDF) transfer lines, a detonator block, detonation transfer manifold, and the APLSC component. PLSCs have previously been designed in ring components where the jet penetrating axis is either directly away or toward the center of the ring assembly. Typically, these PLSC components are designed to cut metal cylinders from the outside inward or from the inside outward. The ODES program requires an annular linear shaped charge. The (Linear Shaped Charge Analysis) LESCA code was used to design this 65 grain/foot APLSC and data comparing the analytically predicted to experimental data are presented. Jet penetration data are presented to assess the maximum depth and reproducibility of the penetration. Data are presented for full scale tests, including all FTS components, and conducted with nominal 19 inch diameter, spherical tanks.

  20. Electrical Resistance Imaging of Bubble Boundary in Annular Two-Phase Flows Using Unscented Kalman Filter

    International Nuclear Information System (INIS)

    For the visualization of the phase boundary in annular two-phase flows, the electrical resistance tomography (ERT) technique is introduced. In ERT, a set of predetermined electrical currents is injected trough the electrodes placed on the boundary of the flow passage and the induced electrical potentials are measured on the electrode. With the relationship between the injected currents and the induced voltages, the electrical conductivity distribution across the flow domain is estimated through the image reconstruction algorithm. In this, the conductivity distribution corresponds to the phase distribution. In the application of ERT to two-phase flows where there are only two conductivity values, the conductivity distribution estimation problem can be transformed into the boundary estimation problem. This paper considers a bubble boundary estimation with ERT in annular two-phase flows. As the image reconstruction algorithm, the unscented Kalman filter (UKF) is adopted since from the control theory it is reported that the UKF shows better performance than the extended Kalman filter (EKF) that has been commonly used. We formulated the UKF algorithm to be incorporate into the image reconstruction algorithm for the present problem. Also, phantom experiments have been conducted to evaluate the improvement by UKF

  1. Analysis of electromagnetic focusing properties of multi-annular nanostructured metasurfaces

    Science.gov (United States)

    Yang, Shuming; Wang, Tong; Liu, Tao; Jiang, Zhuangde

    2016-08-01

    To explore the electromagnetic focusing properties of multi-annular nanostructured metasurfaces, the material property, dispersion property, and error-tolerance property have been studied through a combination of the vectorial angular spectrum theory and the three-dimensional finite-difference time-domain (FDTD) method. An obvious focal shift has been observed and the thickness for the Ag, Al, and Au films is suggested to be within the range of 50-100 nm for the illumination wavelength of 640 nm. The light dispersion effect of the metasurface is remarkable and the focal length decreases with the increase of the wavelength; however, the on-axis intensity distributions retain a similar, shifted shape when the wavelength deviation is less than 10 nm. The fabrication error has a strong impact on the on-axis intensity distribution; when it occurs for the middle annulus, a more severe impact will be induced. The above findings provide theoretical guidance for applying multi-annular metasurfaces in the fields of super-resolution focusing, micro-nano fabrication, and nanoscopic imaging.

  2. Effect of Spray Cone Angle on Flame Stability in an Annular Gas Turbine Combustor

    Science.gov (United States)

    Mishra, R. K.; Kumar, S. Kishore; Chandel, Sunil

    2016-04-01

    Effect of fuel spray cone angle in an aerogas turbine combustor has been studied using computational fluid dynamics (CFD) and full-scale combustor testing. For CFD analysis, a 22.5° sector of an annular combustor is modeled and the governing equations are solved using the eddy dissipation combustion model in ANSYS CFX computational package. The analysis has been carried out at 125 kPa and 303 K inlet conditions for spray cone angles from 60° to 140°. The lean blowout limits are established by studying the behavior of combustion zone during transient engine operation from an initial steady-state condition. The computational study has been followed by testing the practical full-scale annular combustor in an aerothermal test facility. The experimental result is in a good agreement with the computational predictions. The lean blowout fuel-air ratio increases as the spray cone angle is decreased at constant operating pressure and temperature. At higher spray cone angle, the flame and high-temperature zone moves upstream close to atomizer face and a uniform flame is sustained over a wide region causing better flame stability.

  3. A novel reactor concept for boron neutron capture therapy: annular low-low power reactor (ALLPR)

    Energy Technology Data Exchange (ETDEWEB)

    Petrovic, B.; Levine, S.H. [Department of Nuclear Engineering, Pennsylvania State University, University Park, PA 16802 (United States)

    1998-07-01

    Boron Neutron Capture Therapy (BNC), originally proposed in 50's, has been getting renewed attention over the last {approx}10 years. This is in particular due to its potential for treating deep-seated brain tumors by employing epithermal neutron beams. Large (several MW) research reactors are currently used to obtain epithermal beams for BNCT, but because of cost and licensing issues it is not likely that such high-power reactors can be placed in regular medical centers. This paper describes a novel reactor concept for BNCT devised to overcome this obstacle. The design objective was to produce a beam of epithermal neutrons of sufficient intensity for BNCT at <50 kW using low enriched uranium. It is achieved by the annular reactor design, which is called Annular Low-Low Power Reactor (ALLPR). Preliminary studies using Monte Carlo simulations are summarized in this paper. The ALLPR should be relatively economical to build, and safe and easy to operate. This novel concept may increase the viability of using BNCT in medical centers worldwide. (author)

  4. On the burnout in annular channels at non-uniform heat release distribution in length

    International Nuclear Information System (INIS)

    The effect of axial heat release non-uniformity on the conditions of the burnout in annular channels is investigated. The investigation is carried out in annular channels with different laws of heat flux density distribution by channel length. The heat release non-uniformity coefficient was varied from 4.4 to 10, the pressure from 9.8 to 17.6 MPa, mass rate from 500 to 1700 kg (m2xS), liquid temperature (chemically desalted water) at the channel inlet constituted 30-300 deg C. The experiments have been performed at the test bench with a closed circulation circuit. The data obtained testify to the fact that under non-uniform heat release the influence of main operating parameters on the value of critical power is of the same character as under uniform heat release. The character of wall temperature variation by channel length before the burnout is determined by the form of heat supply temperature profile. The temperature maximum is observed in the region lying behind the cross section with maximum heat flux. The conclusion is drawn that the dominant influence on the position of the cross section in which the burnout arises is exerted by the form of heat flux density distribution by length. Independently of this distribution form the burnout developes when the vapour content near the wall reaches a limiting value

  5. Non-Newtonian fluid flow in annular pipes and entropy generation: Temperature-dependent viscosity

    Indian Academy of Sciences (India)

    M Yürüsoy; B S Yilbaş; M Pakdemirli

    2006-12-01

    Non-Newtonian fluid flow in annular pipes is considered and the entropy generation due to fluid friction and heat transfer in them is formulated. A third-grade fluid is employed to account for the non-Newtonian effect, while the Reynolds model is accommodated for temperature-dependent viscosity. Closed-form solutions for velocity, temperature, and entropy fields are presented. It is found that entropy generation number increases with reducing non-Newtonian parameter, while it is the reverse for the viscosity parameter, which is more pronounced in the region close to the annular pipe inner wall.

  6. Slanted annular aperture arrays as enhanced-transmission metamaterials: Excitation of the plasmonic transverse electromagnetic guided mode

    Energy Technology Data Exchange (ETDEWEB)

    Ndao, Abdoulaye; Salut, Roland; Baida, Fadi I., E-mail: fbaida@univ-fcomte.fr [Département d' Optique P.M. Duffieux, Institut FEMTO-ST, UMR 6174 CNRS, Université de Franche–Comté, 25030 Besançon Cedex (France); Belkhir, Abderrahmane [Laboratoire de Physique et Chimie Quantique, Université Mouloud Mammeri, Tizi-Ouzou (Algeria)

    2013-11-18

    We present here the fabrication and the optical characterization of slanted annular aperture arrays engraved into silver film. An experimental enhanced transmission based on the excitation of the cutoff-less plasmonic guided mode of the nano-waveguides (the transmission electron microscopy mode) is demonstrated and agrees well with the theoretical predicted results. By the way, even if it is less efficient (70% → 20%), an enhanced transmission can occur at larger wavelength value (720 nm–930 nm) compared to conventional annular aperture arrays structure by correctly setting the metal thickness.

  7. Quantifying the eddy-jet feedback strength of the annular mode in an idealized GCM and reanalysis data

    OpenAIRE

    Ma, Ding; Hassanzadeh, Pedram; Kuang, Zhiming

    2016-01-01

    A linear response function (LRF) that relates the temporal tendency of zonal mean temperature and zonal wind to their anomalies and external forcing is used to accurately quantify the strength of the eddy-jet feedback associated with the annular mode in an idealized GCM. Following a simple feedback model, the results confirm the presence of a positive eddy-jet feedback in the annular mode dynamics, with a feedback strength of 0.137 day$^{-1}$ in the idealized GCM. Statistical methods proposed...

  8. The Design and Manufacturing Report of Non-Instrumented Rig for Dual-cooled Annular Fuel Irradiation Test in HANARO

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Dae Ho; Bang, Je Geon; Lim, Ik Sung; Kim, Sun Ki; Yang, Yong Sik; Song, Kun Woo; Seo, Chul Gyo; Park, Chan Kook

    2008-09-15

    This project is preparing to irradiation test of the developed double cooled annular fuel pellet in HANARO for pursuit advanced performance in High Performance Fuel Technology Development as a part Nuclear Mid and Long-term R and D Program. On the basis test rod is performed the nuclei property and preliminary fuel performance analysis, test rod and non-instrumented rig designed and manufactured for irradiation test in HANARO OR hole. This non- instrumented rig was confirmed the compatibility of HANARO and the integrity of rig structure, and satisfied the quality assurance requirements. This non- instrumented rig is adopt to the irradiation test for double cooled annular fuel pellet in HANARO.

  9. The Viable Mitral Annular Dynamics and Left Ventricular Function after Mitral Valve Repair by Biological Rings

    Directory of Open Access Journals (Sweden)

    Farideh Roshanali

    2012-12-01

    Full Text Available Objective: Considering the importance of annular dynamics in the valvular and ventricular function, we sought to evaluate the effects of treated pericardial annuloplasty rings on mitral annular dynamics and left-ventricular (LV function after mitral valve repair. The results were compared with the mitral annular dynamics and LV function in patients with rigid and flexible rings and also in those without any heart problems. Materials and Methods: One hundred and thirty-six consecutive patients with a myxomatous mitral valve and severe regurgitation were prospectively enrolled in this observational cohort study. The patients underwent comparable surgical mitral valve reconstruction; of these 100 received autologous pericardium rings (Group I, 20 were given flexible prosthetic rings (Group II, and 16 received rigid rings (Group III. Other repair modalities were also performed, depending on the involved segments. The patients were compared with 100 normal subjects in whom an evaluation of the coronary artery was not indicative of valvular or myocardial abnormalities (Group IV. At follow-up, LV systolic indices were assessed via two-dimensional echocardiography at rest and during dobutamine stress echocardiography. Mitral annular motion was examined through mitral annulus systolic excursion (MASE. Peak transmitral flow velocities (TMFV and mitral valve area (MVA were also evaluated by means of continuous-wave Doppler. Results: A postoperative echocardiographic study showed significant mitral regurgitation (>=2+ in one patient in Group I, one patient in Group II, and none in Group III. None of the patients died. There was a noteworthy increase in TMFV with stress in all the groups, the increase being more considerable in the prosthetic ring groups (Group I from 1.10 ± 0.08 to 1.36 ± 0.13 m/s, Group II from 1.30 ± 0.11 to 1.59 ± 0.19 m/s, Group III from 1.33 ± 0.09 to 1.69 ± 0.21 m/s, and Group IV from 1.08 ± 0.08 to 1.21 ± 0.12 m

  10. KNK II third core: design report for the annular fuel elements on the central position to accommodate material test inserts NZ 402 and NZ 403

    International Nuclear Information System (INIS)

    Since August 1984 irradiation experiments with temperature controlled pressure tube probes are being performed in the central position of KNK II. This is part of a long-term experimental program for the development of irradiation resistant reactor materials, which shall also be continued in the third core. The necessary irradiation channel is provided by a special annular fuel element. The present report describes the annular fuel elements for the third core. Aspects of the subassembly design are considered on the basis of the annular element design for the second core and the standard elements of the third core. Two annular elements NZ 402 and NZ 403 (as reserve) are available. It is demonstrated that the expected loadings will allow an unperturbed operation of the annular elements on the central position of the third core

  11. Information on Stem Cell Research

    Science.gov (United States)

    ... Enhancing Diversity Find People About NINDS Information on Stem Cell Research Research @ NINDS Stem Cell Highlights Submit a hESC ... found here: Human Induced Pluripotent Stem Cells NINDS Stem Cell Research on Campus The Intramural Research Program of NINDS ...

  12. Stem Cell Information: Glossary

    Science.gov (United States)

    ... Neurons Oligodendrocyte Parthenogenesis Passage Pluripotent Polar body Preimplantation Proliferation Regenerative medicine Reproductive cloning Signals Somatic cell Somatic cell nuclear transfer (SCNT) Somatic (adult) stem cell Stem cells Stromal cells Subculturing Surface markers ...

  13. Annular electron beam production on gamble II using a magnetically insulated splitter

    International Nuclear Information System (INIS)

    Annular electron beams have been tested using a post-hole convolute or magnetically insulated splitter (MIS) to feed current to both sides of a ring cathode. Beams were produced on the BLACKJACK 3 generator using a coaxial feed and from BLACKJACK 5 with a triplate feed. On BLACKJACK 3, annular cathodes with 5 cm and 10 cm mean diameters were tested. The cathodes were fed in four places by a MIS. The cathodes were 1.2 cm wide made from stainless steel or brass. Typical anode/cathode gap spacings were 0.6 cm. Experiments were performed at power levels of about 0.6 TW and energies of 30-40 kJ. Typical voltages were 0:6-1 MV with currents of about 0.8 MA. Diagnostics were diode voltage, diode current, and an X-ray pinhole camera. For the 10 cm cathode, current was measured before and after the MIS. The current on each side of the ring was measured separately. The beam voltage was determined from the diode voltage by an inductive correction. The annular beams had a linear current density of about 30 kA/cm and about 60 kA/cm for the 10 cm and 5 cm, respectively. The beam diameter at the cathode could be varied by changing the inductance on each side of the ring cathode and thereby the current balance. The impedance behavior could be modeled using the critical current formulation with a closure velocity of 3.5-4.5 cm/us. The BLACKJACK 5 geometry was a triplate feed. The ring cathode was fed by generators of 0.5 and 0.75 Ω, respectively. The MIS was used to combine the power before the cathode. The cathode had a mean diameter of 25 cm and width of 1.5-3 cm. Experiments were performed at power levels up to about6 TW and energies greater than or equal to200 kJ. Typical operating parameters were about 2 MV and 3 MA

  14. What are Stem Cells?

    OpenAIRE

    Ahmadshah Farhat; Ashraf Mohammadzadeh; M. Rezaie

    2014-01-01

      Stem cells are undifferentiated self regenerating multi potential cells. There are three types of stem cells categories by the ability to form after cells and correlated with the body’s development process. Totipotent: these stem cells can form an entire organism such as fertilized egg. Ploripotent: ploripotent cells are those that can form any cell in the body but cannot form an entire organism such as developing embryo’s totipotent cells become ploripotent  Multipotent: Multi potent stem ...

  15. Optimizing stem cell culture.

    OpenAIRE

    van der Sanden, Boudewijn; Dhobb, Mehdi; Berger, François; Wion, Didier

    2010-01-01

    International audience Stem cells always balance between self-renewal and differentiation. Hence, stem cell culture parameters are critical and need to be continuously refined according to progress in our stem cell biology understanding and the latest technological developments. In the past few years, major efforts have been made to define more precisely the medium composition in which stem cells grow or differentiate. This led to the progressive replacement of ill-defined additives such a...

  16. Hepatic stem cell niches

    OpenAIRE

    Kordes, Claus; Häussinger, Dieter

    2013-01-01

    Stem cell niches are special microenvironments that maintain stem cells and control their behavior to ensure tissue homeostasis and regeneration throughout life. The liver has a high regenerative capacity that involves stem/progenitor cells when the proliferation of hepatocytes is impaired. In recent years progress has been made in the identification of potential hepatic stem cell niches. There is evidence that hepatic progenitor cells can originate from niches in the canals...

  17. Artificial Stem Cell Niches

    OpenAIRE

    Lutolf, Matthias P.; Blau, Helen M.

    2009-01-01

    Stem cells are characterized by their dual ability to reproduce themselves (self-renew) and specialize (differentiate), yielding a plethora of daughter cells that maintain and regenerate tissues. In contrast to their embryonic counterparts, adult stem cells retain their unique functions only if they are in intimate contact with an instructive microenvironment, termed stem cell niche. In these niches, stem cells integrate a complex array of molecular signals that, in concert with induced cell-...

  18. Intraoperative Stem Cell Therapy

    OpenAIRE

    Coelho, Mónica Beato; Cabral, Joaquim M. S.; Karp, Jeffrey M.

    2012-01-01

    Stem cells hold significant promise for regeneration of tissue defects and disease-modifying therapies. Although numerous promising stem cell approaches are advancing in clinical trials, intraoperative stem cell therapies offer more immediate hope by integrating an autologous cell source with a well-established surgical intervention in a single procedure. Herein, the major developments in intraoperative stem cell approaches, from in vivo models to clinical studies, are reviewed, and the poten...

  19. Natural convection of high-temperature, high-pressure gas in a horizontal annular layer of thermal insulator, (1)

    International Nuclear Information System (INIS)

    Numerical calculations are described of the natural convection in a horizontal annular layer of thermal insulator. The purpose is to compare the numerical results for variable physical properties with those for constant properties. The numerical procedure and typical results are presented. (author)

  20. High-Flux Femtosecond X-Ray Emission from Controlled Generation of Annular Electron Beams in a Laser Wakefield Accelerator.

    Science.gov (United States)

    Zhao, T Z; Behm, K; Dong, C F; Davoine, X; Kalmykov, S Y; Petrov, V; Chvykov, V; Cummings, P; Hou, B; Maksimchuk, A; Nees, J A; Yanovsky, V; Thomas, A G R; Krushelnick, K

    2016-08-26

    Annular quasimonoenergetic electron beams with a mean energy in the range 200-400 MeV and charge on the order of several picocoulombs were generated in a laser wakefield accelerator and subsequently accelerated using a plasma afterburner in a two-stage gas cell. Generation of these beams is associated with injection occurring on the density down ramp between the stages. This well-localized injection produces a bunch of electrons performing coherent betatron oscillations in the wakefield, resulting in a significant increase in the x-ray yield. Annular electron distributions are detected in 40% of shots under optimal conditions. Simultaneous control of the pulse duration and frequency chirp enables optimization of both the energy and the energy spread of the annular beam and boosts the radiant energy per unit charge by almost an order of magnitude. These well-defined annular distributions of electrons are a promising source of high-brightness laser plasma-based x rays. PMID:27610860