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Sample records for annular dark-field images

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

    PubMed

    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.

  2. Influence of spatial and temporal coherences on atomic resolution high angle annular dark field imaging.

    PubMed

    Beyer, Andreas; Belz, Jürgen; Knaub, Nikolai; Jandieri, Kakhaber; Volz, Kerstin

    2016-10-01

    Aberration-corrected (scanning) transmission electron microscopy ((S)TEM) has become a widely used technique when information on the chemical composition is sought on an atomic scale. To extract the desired information, complementary simulations of the scattering process are inevitable. Often the partial spatial and temporal coherences are neglected in the simulations, although they can have a huge influence on the high resolution images. With the example of binary gallium phosphide (GaP) we elucidate the influence of the source size and shape as well as the chromatic aberration on the high angle annular dark field (HAADF) intensity. We achieve a very good quantitative agreement between the frozen phonon simulation and experiment for different sample thicknesses when a Lorentzian source distribution is assumed and the effect of the chromatic aberration is considered. Additionally the influence of amorphous layers introduced by the preparation of the TEM samples is discussed. Taking into account these parameters, the intensity in the whole unit cell of GaP, i.e. at the positions of the different atomic columns and in the region between them, is described correctly. With the knowledge of the decisive parameters, the determination of the chemical composition of more complex, multinary materials becomes feasible.

  3. Detection of large thermal vibration for Cu atoms in tetrahedrite by high-angle annular dark-field imaging

    NASA Astrophysics Data System (ADS)

    Prasad Mishra, Tara; Koyano, Mikio; Oshima, Yoshifumi

    2017-04-01

    Tetrahedrite (Cu12Sb4S13) is a new type of thermoelectric material with an extremely low thermal conductivity attributed to the anomalous large thermal vibration of specific Cu sites. The tetrahedrite crystal was observed from the [111] direction by high-angle annular dark-field (HAADF) imaging and the image intensity was found to be 64% lower at specific sites. This could be explained by the blurring of the intensity distribution owing to a large atomic displacement, suggesting that anomalous large thermal vibrations at specific sites in the crystal can be distinguished in HAADF images.

  4. Quantitative annular dark-field imaging of single-layer graphene-II: atomic-resolution image contrast.

    PubMed

    Yamashita, Shunsuke; Koshiya, Shogo; Nagai, Takuro; Kikkawa, Jun; Ishizuka, Kazuo; Kimoto, Koji

    2015-12-01

    We have investigated how accurately atomic-resolution annular dark-field (ADF) images match between experiments and simulations to conduct more reliable crystal structure analyses. Quantitative ADF imaging, in which the ADF intensity at each pixel represents the fraction of the incident probe current, allows us to perform direct comparisons with simulations without the use of fitting parameters. Although the conventional comparison suffers from experimental uncertainties such as an amorphous surface layer and specimen thickness, in this study we eliminated such uncertainties by using a single-layer graphene as a specimen. Furthermore, to reduce image distortion and shot noises in experimental images, multiple acquisitions with drift correction were performed, and the atomic ADF contrast was quantitatively acquired. To reproduce the experimental ADF contrast, we used three distribution functions as the effective source distribution in simulations. The optimum distribution function and its full-width at half-maximum were evaluated by measuring the residuals between the experimental and simulated images. It was found that the experimental images could be explained well by a linear combination of a Gaussian function and a Lorentzian function with a longer tail than the Gaussian function.

  5. Modelling of AlAs/GaAs interfacial structures using high-angle annular dark field (HAADF) image simulations.

    PubMed

    Robb, Paul D; Finnie, Michael; Craven, Alan J

    2012-07-01

    High angle annular dark field (HAADF) image simulations were performed on a series of AlAs/GaAs interfacial models using the frozen-phonon multislice method. Three general types of models were considered-perfect, vicinal/sawtooth and diffusion. These were chosen to demonstrate how HAADF image measurements are influenced by different interfacial structures in the technologically important III-V semiconductor system. For each model, interfacial sharpness was calculated as a function of depth and compared to aberration-corrected HAADF experiments of two types of AlAs/GaAs interfaces. The results show that the sharpness measured from HAADF imaging changes in a complicated manner with thickness for complex interfacial structures. For vicinal structures, it was revealed that the type of material that the probe projects through first of all has a significant effect on the measured sharpness. An increase in the vicinal angle was also shown to generate a wider interface in the random step model. The Moison diffusion model produced an increase in the interface width with depth which closely matched the experimental results of the AlAs-on-GaAs interface. In contrast, the interface width decreased as a function of depth in the linear diffusion model. Only in the case of the perfect model was it possible to ascertain the underlying structure directly from HAADF image analysis.

  6. Oxidation-state sensitive imaging of cerium dioxide by atomic-resolution low-angle annular dark field scanning transmission electron microscopy

    PubMed Central

    Johnston-Peck, Aaron C.; Winterstein, Jonathan P.; Roberts, Alan D.; DuChene, Joseph S.; Qian, Kun; Sweeny, Brendan C.; Wei, Wei David; Sharma, Renu; Stach, Eric A.; Herzing, Andrew A.

    2016-01-01

    Low-angle annular dark field (LAADF) scanning transmission electron microscopy (STEM) imaging is presented as a method that is sensitive to the oxidation state of cerium ions in CeO2 nanoparticles. This relationship was validated through electron energy loss spectroscopy (EELS), in situ measurements, as well as multislice image simulations. Static displacements caused by the increased ionic radius of Ce3+ influence the electron channeling process and increase electron scattering to low angles while reducing scatter to high angles. This process manifests itself by reducing the high-angle annular dark field (HAADF) signal intensity while increasing the LAADF signal intensity in close proximity to Ce3+ ions. This technique can supplement STEM-EELS and in so doing, relax the experimental challenges associated with acquiring oxidation state information at high spatial resolutions. PMID:26744830

  7. Oxidation-state sensitive imaging of cerium dioxide by atomic-resolution low-angle annular dark field scanning transmission electron microscopy.

    PubMed

    Johnston-Peck, Aaron C; Winterstein, Jonathan P; Roberts, Alan D; DuChene, Joseph S; Qian, Kun; Sweeny, Brendan C; Wei, Wei David; Sharma, Renu; Stach, Eric A; Herzing, Andrew A

    2016-03-01

    Low-angle annular dark field (LAADF) scanning transmission electron microscopy (STEM) imaging is presented as a method that is sensitive to the oxidation state of cerium ions in CeO2 nanoparticles. This relationship was validated through electron energy loss spectroscopy (EELS), in situ measurements, as well as multislice image simulations. Static displacements caused by the increased ionic radius of Ce(3+) influence the electron channeling process and increase electron scattering to low angles while reducing scatter to high angles. This process manifests itself by reducing the high-angle annular dark field (HAADF) signal intensity while increasing the LAADF signal intensity in close proximity to Ce(3+) ions. This technique can supplement STEM-EELS and in so doing, relax the experimental challenges associated with acquiring oxidation state information at high spatial resolutions.

  8. Quantitative annular dark field electron microscopy using single electron signals.

    PubMed

    Ishikawa, Ryo; Lupini, Andrew R; Findlay, Scott D; Pennycook, Stephen J

    2014-02-01

    One of the difficulties in analyzing atomic resolution electron microscope images is that the sample thickness is usually unknown or has to be fitted from parameters that are not precisely known. An accurate measure of thickness, ideally on a column-by-column basis, parameter free, and with single atom accuracy, would be of great value for many applications, such as matching to simulations. Here we propose such a quantification method for annular dark field scanning transmission electron microscopy by using the single electron intensity level of the detector. This method has the advantage that we can routinely quantify annular dark field images operating at both low and high beam currents, and under high dynamic range conditions, which is useful for the quantification of ultra-thin or light-element materials. To facilitate atom counting at the atomic scale we use the mean intensity in an annular dark field image averaged over a primitive cell, with no free parameters to be fitted. To illustrate the potential of our method, we demonstrate counting the number of Al (or N) atoms in a wurtzite-type aluminum nitride single crystal at each primitive cell over the range of 3-99 atoms.

  9. Annular dark field transmission electron microscopy for protein structure determination.

    PubMed

    Koeck, Philip J B

    2016-02-01

    Recently annular dark field (ADF) transmission electron microscopy (TEM) has been advocated as a means of recording images of biological specimens with better signal to noise ratio (SNR) than regular bright field images. I investigate whether and how such images could be used to determine the three-dimensional structure of proteins given that an ADF aperture with a suitable pass-band can be manufactured and used in practice. I develop an approximate theory of ADF-TEM image formation for weak amplitude and phase objects and test this theory using computer simulations. I also test whether these simulated images can be used to calculate a three-dimensional model of the protein using standard software and discuss problems and possible ways to overcome these.

  10. The effect of probe inaccuracies on the quantitative model-based analysis of high angle annular dark field scanning transmission electron microscopy images.

    PubMed

    Martinez, G T; De Backer, A; Rosenauer, A; Verbeeck, J; Van Aert, S

    2014-08-01

    Quantitative structural and chemical information can be obtained from high angle annular dark field scanning transmission electron microscopy (HAADF STEM) images when using statistical parameter estimation theory. In this approach, we assume an empirical parameterized imaging model for which the total scattered intensities of the atomic columns are estimated. These intensities can be related to the material structure or composition. Since the experimental probe profile is assumed to be known in the description of the imaging model, we will explore how the uncertainties in the probe profile affect the estimation of the total scattered intensities. Using multislice image simulations, we analyze this effect for Cs corrected and non-Cs corrected microscopes as a function of inaccuracies in cylindrically symmetric aberrations, such as defocus and spherical aberration of third and fifth order, and non-cylindrically symmetric aberrations, such as 2-fold and 3-fold astigmatism and coma.

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

    PubMed

    Mehrtens, Thorsten; Müller, Knut; Schowalter, Marco; Hu, Dongzhi; Schaadt, Daniel M; Rosenauer, Andreas

    2013-08-01

    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.. 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).

  12. Extraction of structural and chemical information from high angle annular dark-field image by an improved peaks finding method.

    PubMed

    Yin, Wenhao; Huang, Rong; Qi, Ruijuan; Duan, Chungang

    2016-09-01

    With the development of spherical aberration (Cs) corrected scanning transmission electron microscopy (STEM), high angle annular dark filed (HAADF) imaging technique has been widely applied in the microstructure characterization of various advanced materials with atomic resolution. However, current qualitative interpretation of the HAADF image is not enough to extract all the useful information. Here a modified peaks finding method was proposed to quantify the HAADF-STEM image to extract structural and chemical information. Firstly, an automatic segmentation technique including numerical filters and watershed algorithm was used to define the sub-areas for each atomic column. Then a 2D Gaussian fitting was carried out to determine the atomic column positions precisely, which provides the geometric information at the unit-cell scale. Furthermore, a self-adaptive integration based on the column position and the covariance of statistical Gaussian distribution were performed. The integrated intensities show very high sensitivity on the mean atomic number with improved signal-to-noise (S/N) ratio. Consequently, the polarization map and strain distributions were rebuilt from a HAADF-STEM image of the rhombohedral and tetragonal BiFeO3 interface and a MnO2 monolayer in LaAlO3 /SrMnO3 /SrTiO3 heterostructure was discerned from its neighbor TiO2 layers. Microsc. Res. Tech. 79:820-826, 2016. © 2016 Wiley Periodicals, Inc.

  13. Microstructure study of a severely plastically deformed Mg-Zn-Y alloy by application of low angle annular dark field diffraction contrast imaging

    PubMed Central

    Basha, Dudekula Althaf; Rosalie, Julian M.; Somekawa, Hidetoshi; Miyawaki, Takashi; Singh, Alok; Tsuchiya, Koichi

    2016-01-01

    Microstructural investigation of extremely strained samples, such as severely plastically deformed (SPD) materials, by using conventional transmission electron microscopy techniques is very challenging due to strong image contrast resulting from the high defect density. In this study, low angle annular dark field (LAADF) imaging mode of scanning transmission electron microscope (STEM) has been applied to study the microstructure of a Mg-3Zn-0.5Y (at%) alloy processed by high pressure torsion (HPT). LAADF imaging advantages for observation of twinning, grain fragmentation, nucleation of recrystallized grains and precipitation on second phase particles in the alloy processed by HPT are highlighted. By using STEM-LAADF imaging with a range of incident angles, various microstructural features have been imaged, such as nanoscale subgrain structure and recrystallization nucleation even from the thicker region of the highly strained matrix. It is shown that nucleation of recrystallized grains starts at a strain level of revolution N=1/4 (earlier than detected by conventional bright field imaging). Occurrence of recrystallization of grains by nucleating heterogeneously on quasicrystalline particles is also confirmed. Minimizing all strain effects by LAADF imaging facilitated grain size measurement of 150±25 nm in fully recrystallized HPT specimen after N=5. PMID:27877863

  14. Three-dimensional imaging of individual point defects using selective detection angles in annular dark field scanning transmission electron microscopy.

    PubMed

    Johnson, Jared M; Im, Soohyun; Windl, Wolfgang; Hwang, Jinwoo

    2017-01-01

    We propose a new scanning transmission electron microscopy (STEM) technique that can realize the three-dimensional (3D) characterization of vacancies, lighter and heavier dopants with high precision. Using multislice STEM imaging and diffraction simulations of β-Ga2O3 and SrTiO3, we show that selecting a small range of low scattering angles can make the contrast of the defect-containing atomic columns substantially more depth-dependent. The origin of the depth-dependence is the de-channeling of electrons due to the existence of a point defect in the atomic column, which creates extra "ripples" at low scattering angles. The highest contrast of the point defect can be achieved when the de-channeling signal is captured using the 20-40mrad detection angle range. The effect of sample thickness, crystal orientation, local strain, probe convergence angle, and experimental uncertainty to the depth-dependent contrast of the point defect will also be discussed. The proposed technique therefore opens new possibilities for highly precise 3D structural characterization of individual point defects in functional materials.

  15. Annular dark-field scanning transmission electron microscopy (ADF-STEM) tomography of polymer systems.

    PubMed

    Lu, Kangbo; Sourty, Erwan; Loos, Joachim

    2010-08-01

    We have utilized bright-field conventional transmission electron microscopy tomography and annular dark-field scanning transmission electron microscopy (ADF-STEM) tomography to characterize a well-defined carbon black (CB)-filled polymer nanocomposite with known CB volume concentration. For both imaging methods, contrast can be generated between the CB and the surrounding polymer matrix. The involved contrast mechanisms, in particular for ADF-STEM, will be discussed in detail. The obtained volume reconstructions were analysed and the CB volume concentrations were carefully determined from the reconstructed data. For both imaging modes, the measured CB volume concentrations are substantially different and only quantification based on the ADF-STEM data revealed about the same value as the known CB loading. Moreover, when applying low-convergence angles for imaging ADF-STEM tomography, data can be obtained of micrometre-thick samples.

  16. Dark Field Imaging of Plasmonic Resonator Arrays

    NASA Astrophysics Data System (ADS)

    Aydinli, Atilla; Balci, Sinan; Karademir, Ertugrul; Kocabas, Coskun

    2012-02-01

    We present critical coupling of electromagnetic waves to plasmonic cavity arrays fabricated on Moir'e surfaces. The critical coupling condition depends on the superperiod of Moir'e surface, which also defines the coupling between the cavities. Complete transfer of the incident power can be achieved for traveling wave plasmonic resonators, which have relatively short superperiod. When the superperiod of the resonators increases, the coupled resonators become isolated standing wave resonators in which complete transfer of the incident power is not possible. Dark field plasmon microscopy imaging and polarization dependent spectroscopic reflection measurements reveal the critical coupling conditions of the cavities. We image the light scattered from SPPs in the plasmonic cavities excited by a tunable light source. Tuning the excitation wavelength, we measure the localization and dispersion of the plasmonic cavity mode. Dark field imaging has been achieved in the Kretschmann configuration using a supercontinuum white light laser equipped with an acoustooptic tunable filter. Polarization dependent spectroscopic reflection and dark field imaging measurements are correlated and found to be in agreement with FDTD simulations.

  17. Dark-field third-harmonic imaging

    NASA Astrophysics Data System (ADS)

    Doronina-Amitonova, L. V.; Lanin, A. A.; Fedotov, I. V.; Ivashkina, O. I.; Zots, M. A.; Fedotov, A. B.; Anokhin, K. V.; Zheltikov, A. M.

    2013-08-01

    Coherent cancellation of third-harmonic generation (THG) in a tightly focused laser beam is shown to enable a label-free imaging of individual neurons in representative brain tissues. The intrinsic coherence of third-harmonic buildup and cancellation combined with the nonlinear nature of the process enhances the locality of the dark signal in THG, translating into a remarkable sharpness of dark-field THG images. Unique advantages of this technique for high-contrast subcellular-resolution neuroimaging are demonstrated by comparing THG images of hippocampus and somatosensory cortex in a mouse brain with images visualizing fluorescent protein biomarkers.

  18. Unscrambling Mixed Elements using High Angle Annular Dark Field Scanning Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    van den Bos, Karel H. W.; De Backer, Annick; Martinez, Gerardo T.; Winckelmans, Naomi; Bals, Sara; Nellist, Peter D.; Van Aert, Sandra

    2016-06-01

    The development of new nanocrystals with outstanding physicochemical properties requires a full three-dimensional (3D) characterization at the atomic scale. For homogeneous nanocrystals, counting the number of atoms in each atomic column from high angle annular dark field scanning transmission electron microscopy images has been shown to be a successful technique to get access to this 3D information. However, technologically important nanostructures often consist of more than one chemical element. In order to extend atom counting to heterogeneous materials, a new atomic lensing model is presented. This model takes dynamical electron diffraction into account and opens up new possibilities for unraveling the 3D composition at the atomic scale. Here, the method is applied to determine the 3D structure of Au@Ag core-shell nanorods, but it is applicable to a wide range of heterogeneous complex nanostructures.

  19. Unscrambling Mixed Elements using High Angle Annular Dark Field Scanning Transmission Electron Microscopy.

    PubMed

    van den Bos, Karel H W; De Backer, Annick; Martinez, Gerardo T; Winckelmans, Naomi; Bals, Sara; Nellist, Peter D; Van Aert, Sandra

    2016-06-17

    The development of new nanocrystals with outstanding physicochemical properties requires a full three-dimensional (3D) characterization at the atomic scale. For homogeneous nanocrystals, counting the number of atoms in each atomic column from high angle annular dark field scanning transmission electron microscopy images has been shown to be a successful technique to get access to this 3D information. However, technologically important nanostructures often consist of more than one chemical element. In order to extend atom counting to heterogeneous materials, a new atomic lensing model is presented. This model takes dynamical electron diffraction into account and opens up new possibilities for unraveling the 3D composition at the atomic scale. Here, the method is applied to determine the 3D structure of Au@Ag core-shell nanorods, but it is applicable to a wide range of heterogeneous complex nanostructures.

  20. Mapping of valence energy losses via energy-filtered annular dark-field scanning transmission electron microscopy.

    PubMed

    Gu, Lin; Sigle, Wilfried; Koch, Christoph T; Nelayah, Jaysen; Srot, Vesna; van Aken, Peter A

    2009-08-01

    The advent of electron monochromators has opened new perspectives on electron energy-loss spectroscopy at low energy losses, including phenomena such as surface plasmon resonances or electron transitions from the valence to the conduction band. In this paper, we report first results making use of the combination of an energy filter and a post-filter annular dark-field detector. This instrumental design allows us to obtain energy-filtered (i.e. inelastic) annular dark-field images in scanning transmission electron microscopy of the 2-dimensional semiconductor band-gap distribution of a GaN/Al(45)Ga(55)N structure and of surface plasmon resonances of silver nanoprisms. In comparison to other approaches, the technique is less prone to inelastic delocalization and relativistic artefacts. The mixed contribution of elastic and inelastic contrast is discussed.

  1. Quantitative atomic resolution mapping using high-angle annular dark field scanning transmission electron microscopy.

    PubMed

    Van Aert, S; Verbeeck, J; Erni, R; Bals, S; Luysberg, M; Van Dyck, D; Van Tendeloo, G

    2009-09-01

    A model-based method is proposed to relatively quantify the chemical composition of atomic columns using high angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) images. The method is based on a quantification of the total intensity of the scattered electrons for the individual atomic columns using statistical parameter estimation theory. In order to apply this theory, a model is required describing the image contrast of the HAADF STEM images. Therefore, a simple, effective incoherent model has been assumed which takes the probe intensity profile into account. The scattered intensities can then be estimated by fitting this model to an experimental HAADF STEM image. These estimates are used as a performance measure to distinguish between different atomic column types and to identify the nature of unknown columns with good accuracy and precision using statistical hypothesis testing. The reliability of the method is supported by means of simulated HAADF STEM images as well as a combination of experimental images and electron energy-loss spectra. It is experimentally shown that statistically meaningful information on the composition of individual columns can be obtained even if the difference in averaged atomic number Z is only 3. Using this method, quantitative mapping at atomic resolution using HAADF STEM images only has become possible without the need of simultaneously recorded electron energy loss spectra.

  2. High-angle annular dark field scanning transmission electron microscopy on carbon-based functional polymer systems.

    PubMed

    Sourty, Erwan; van Bavel, Svetlana; Lu, Kangbo; Guerra, Ralph; Bar, Georg; Loos, Joachim

    2009-06-01

    Two purely carbon-based functional polymer systems were investigated by bright-field conventional transmission electron microscopy (CTEM) and high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). For a carbon black (CB) filled polymer system, HAADF-STEM provides high contrast between the CB agglomerates and the polymer matrix so that details of the interface organization easily can be revealed and assignment of the CB phase is straightforward. For a second system, the functional polymer blend representing the photoactive layer of a polymer solar cell, details of its nanoscale organization could be observed that were not accessible with CTEM. By varying the camera length in HAADF-STEM imaging, the contrast can be enhanced between crystalline and amorphous compounds due to diffraction contrast so that nanoscale interconnections between domains are identified. In general, due to its incoherent imaging characteristics HAADF-STEM allows for reliable interpretation of the data obtained.

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

    PubMed

    De Backer, A; Martinez, G T; MacArthur, K E; Jones, L; Béché, A; Nellist, P D; Van Aert, S

    2015-04-01

    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.

  4. Energy weighted x-ray dark-field imaging.

    PubMed

    Pelzer, Georg; Zang, Andrea; 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

    2014-10-06

    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%.

  5. Quantitative composition determination at the atomic level using model-based high-angle annular dark field scanning transmission electron microscopy.

    PubMed

    Martinez, G T; Rosenauer, A; De Backer, A; Verbeeck, J; Van Aert, S

    2014-02-01

    High angle annular dark field scanning transmission electron microscopy (HAADF STEM) images provide sample information which is sensitive to the chemical composition. The image intensities indeed scale with the mean atomic number Z. To some extent, chemically different atomic column types can therefore be visually distinguished. However, in order to quantify the atomic column composition with high accuracy and precision, model-based methods are necessary. Therefore, an empirical incoherent parametric imaging model can be used of which the unknown parameters are determined using statistical parameter estimation theory (Van Aert et al., 2009, [1]). In this paper, it will be shown how this method can be combined with frozen lattice multislice simulations in order to evolve from a relative toward an absolute quantification of the composition of single atomic columns with mixed atom types. Furthermore, the validity of the model assumptions are explored and discussed.

  6. Directional x-ray dark-field imaging of strongly ordered systems

    SciTech Connect

    Jensen, Torben Haugaard; Feidenhans'l, Robert; Bech, Martin; Pfeiffer, Franz; Zanette, Irene; Weitkamp, Timm; David, Christian; Rutishauser, Simon; Deyhle, Hans; Reznikova, Elena; Mohr, Juergen

    2010-12-01

    Recently a novel grating based x-ray imaging approach called directional x-ray dark-field imaging was introduced. Directional x-ray dark-field imaging yields information about the local texture of structures smaller than the pixel size of the imaging system. In this work we extend the theoretical description and data processing schemes for directional dark-field imaging to strongly scattering systems, which could not be described previously. We develop a simple scattering model to account for these recent observations and subsequently demonstrate the model using experimental data. The experimental data includes directional dark-field images of polypropylene fibers and a human tooth slice.

  7. Dark field imaging of biological macromolecules with the scanning transmission electron microscope

    PubMed Central

    Ohtsuki, Mitsuo; Isaacson, Michael S.; Crewe, A. V.

    1979-01-01

    A scanning transmission electron microscope (STEM) equipped with a field emission gun has been employed for the examination of biological macromolecules at high resolution. The quality of micrographs obtained with the STEM is dependent upon the quality of the substrate used to support biological objects because the image contrast in dark field is proportional to the mass density of the specimen. In order to reduce deleterious effects of the substrates on the image quality, we have developed a method of fabricating substrates consisting of very thin, very clean carbon films supported on very clean fenestrated plastic films. These films are approximately 15 Å thick. Well-known biological macromolecules such as glutamine synthetase and tobacco mosaic virus (both stained) and low-density lipoprotein and ferritin (both unstained were placed on these substrates and examined with the STEM by using various modes of contrast. The micrographs obtained by using the dark field mode of contrast employing an annular detector were free from phase contrast, as expected. Using this contrast mode, we have been able to directly observe (in-focus) 2.5- to 4.4-Å lattice spacings in the ferritin core. The effect of electron radiation damage on the helical structure of tobacco mosaic virus was also examined. Micrographs as well as corresponding optical diffraction patterns obtained with moderately low doses showed very clear helical structure from both sides of the virus. In addition, the (11.5 Å)-1 layer lines indicated the effective resolution attained on these particles. Images PMID:35788

  8. Quantitative Chemical Mapping of InGaN Quantum Wells from Calibrated High-Angle Annular Dark Field Micrographs.

    PubMed

    Carvalho, Daniel; Morales, Francisco M; Ben, Teresa; García, Rafael; Redondo-Cubero, Andrés; Alves, Eduardo; Lorenz, Katharina; Edwards, Paul R; O'Donnell, Kevin P; Wetzel, Christian

    2015-08-01

    We present a simple and robust method to acquire quantitative maps of compositional fluctuations in nanostructures from low magnification high-angle annular dark field (HAADF) micrographs calibrated by energy-dispersive X-ray (EDX) spectroscopy in scanning transmission electron microscopy (STEM) mode. We show that a nonuniform background in HAADF-STEM micrographs can be eliminated, to a first approximation, by use of a suitable analytic function. The uncertainty in probe position when collecting an EDX spectrum renders the calibration of HAADF-STEM micrographs indirect, and a statistical approach has been developed to determine the position with confidence. Our analysis procedure, presented in a flowchart to facilitate the successful implementation of the method by users, was applied to discontinuous InGaN/GaN quantum wells in order to obtain quantitative determinations of compositional fluctuations on the nanoscale.

  9. Estimation of mass thickness response of embedded aggregated silica nanospheres from high angle annular dark-field scanning transmission electron micrographs.

    PubMed

    Nordin, M; Abrahamsson, C; Blomqvist, C H; Häbel, H; Röding, M; Olsson, E; Nydén, M; Rudemo, M

    2014-02-01

    In this study, we investigate the functional behaviour of the intensity in high-angle annular dark field scanning transmission electron micrograph images. The model material is a silica particle (20 nm) gel at 5 wt%. By assuming that the intensity response is monotonically increasing with increasing mass thickness of silica, an estimate of the functional form is calculated using a maximum likelihood approach. We conclude that a linear functional form of the intensity provides a fair estimate but that a power function is significantly better for estimating the amount of silica in the z-direction. The work adds to the development of quantifying material properties from electron micrographs, especially in the field of tomography methods and three-dimensional quantitative structural characterization from a scanning transmission electron micrograph. It also provides means for direct three-dimensional quantitative structural characterization from a scanning transmission electron micrograph.

  10. Hard-X-ray directional dark-field imaging using the speckle scanning technique.

    PubMed

    Wang, Hongchang; Kashyap, Yogesh; Sawhney, Kawal

    2015-03-13

    X-ray dark-field imaging can provide inaccessible and complementary information compared to conventional absorption contrast imaging. However, extraction of the dark-field signal is difficult, and sophisticated optics are often required. In this Letter, we report a novel approach to generate high-quality dark-field images using a simple membrane. The dark-field image is extracted from the maximum correlation coefficient by applying a cross-correlation algorithm to a stack of speckle images collected by scanning a membrane in a transverse direction to the incident x-ray beam. The new method can also provide directional dark-field information, which is extremely useful for the study of strongly ordered systems. The potential of the proposed technique for nondestructive x-ray imaging is demonstrated by imaging representative samples.

  11. Structured dark-field imaging for single nano-particles

    NASA Astrophysics Data System (ADS)

    Chen, Jian; Gao, Kun; Wang, Zhi-Li; Yun, Wen-Bing; Wu, Zi-Yu

    2015-08-01

    In this work, we extensively describe and demonstrate the structured dark-field imaging (SDFI). SDFI is a newly proposed x-ray microscopy designed for revealing the fine features below Rayleigh resolution, in which different orders of scattered x-ray photons are collected by changing the numerical aperture of the condenser. Here, the samples of single particles are discussed to extend the scope of the SDFI technique reported in a previous work (Chen J, Gao K, Ge X, et al. 2013 Opt. Lett. 38 2068). In addition, the details of the newly invented algorithm are explained, which is able to calculate the intensity of any pixel on the image plane rapidly and reliably. Project supported by the National Basic Research Program of China (Grant No. 2012CB825800), the Science Fund for Creative Research Groups, the National Natural Science Foundation of China (Grant No. 11321503), the Knowledge Innovation Program of the Chinese Academy of Sciences (Grant No. KJCX2-YW-N42), and the National Natural Science Foundation of China (Grant Nos. 11475170, 11205157, and 11305173).

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

    PubMed

    van Elteren, H A; Ince, C; Tibboel, D; Reiss, I K M; de Jonge, R C J

    2015-10-01

    Incident 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. In (pre)term neonates the reduced thickness of the skin allows non-invasive transcutaneous measurements. The goal of this study was to compare the existing device (SDF) and its technical successor (IDF) in preterm neonates. We hypothesized that IDF imaging produces higher quality images resulting in a higher vessel density. After written informed consent was given by the parents, skin microcirculation was consecutively measured on the inner upper arm with de SDF and IDF device. Images were exported and analyzed offline using existing software (AVA 3.0). Vessel density and perfusion were calculated using the total vessel density (TVD) proportion of perfused vessels (PPV) and perfused vessel density. The microcirculation images quality score was used to evaluate the quality of the video images. In a heterogeneous group of twenty preterm neonates (median GA 27.6 weeks, range 24-33.4) IDF imaging visualized 19.9% more vessels resulting in a significantly higher vessel density (TVD 16.9 vs. 14.1/mm, p value < 0.001). The perfusion of vessels could be determined more accurately in the IDF images, resulting in a significant lower PPV (88.7 vs. 93.9%, p value 0.002). The IDF video images scored optimal in a higher percentage compared to the SDF video images. IDF imaging of the cutaneous microcirculation in preterm neonates resulted in a higher vessel density and lower perfusion compared to the existing SDF device.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    SciTech Connect

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

    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.

  15. Phosphorus detection in vitrified bacteria by cryo-STEM annular dark-field analysis.

    PubMed

    Wolf, Sharon Grayer; Rez, Peter; Elbaum, Michael

    2015-11-01

    Bacterial cells often contain dense granules. Among these, polyphosphate bodies (PPBs) store inorganic phosphate for a variety of essential functions. Identification of PPBs has until now been accomplished by analytical methods that required drying or chemically fixing the cells. These methods entail large electron doses that are incompatible with low-dose imaging of cryogenic specimens. We show here that Scanning Transmission Electron Microscopy (STEM) of fully hydrated, intact, vitrified bacteria provides a simple means for mapping of phosphorus-containing dense granules based on quantitative sensitivity of the electron scattering to atomic number. A coarse resolution of the scattering angles distinguishes phosphorus from the abundant lighter atoms: carbon, nitrogen and oxygen. The theoretical basis is similar to Z contrast of materials science. EDX provides a positive identification of phosphorus, but importantly, the method need not involve a more severe electron dose than that required for imaging. The approach should prove useful in general for mapping of heavy elements in cryopreserved specimens when the element identity is known from the biological context.

  16. Annular pancreas (image)

    MedlinePlus

    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. A model based iterative reconstruction algorithm for high angle annular dark field-scanning transmission electron microscope (HAADF-STEM) tomography.

    PubMed

    Venkatakrishnan, S V; Drummy, Lawrence F; Jackson, Michael A; De Graef, Marc; Simmons, Jeff; Bouman, Charles A

    2013-11-01

    High angle annular dark field (HAADF)-scanning transmission electron microscope (STEM) data is increasingly being used in the physical sciences to research materials in 3D because it reduces the effects of Bragg diffraction seen in bright field TEM data. Typically, tomographic reconstructions are performed by directly applying either filtered back projection (FBP) or the simultaneous iterative reconstruction technique (SIRT) to the data. Since HAADF-STEM tomography is a limited angle tomography modality with low signal to noise ratio, these methods can result in significant artifacts in the reconstructed volume. In this paper, we develop a model based iterative reconstruction algorithm for HAADF-STEM tomography. We combine a model for image formation in HAADF-STEM tomography along with a prior model to formulate the tomographic reconstruction as a maximum a posteriori probability (MAP) estimation problem. Our formulation also accounts for certain missing measurements by treating them as nuisance parameters in the MAP estimation framework. We adapt the iterative coordinate descent algorithm to develop an efficient method to minimize the corresponding MAP cost function. Reconstructions of simulated as well as experimental data sets show results that are superior to FBP and SIRT reconstructions, significantly suppressing artifacts and enhancing contrast.

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

    SciTech Connect

    Araújo, D.; Alegre, M. P.; Piñero, J. C.; Fiori, A.; Bustarret, E.; Jomard, F.

    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.

  19. Refraction-contrast tomosynthesis imaging using dark-field imaging optics

    NASA Astrophysics Data System (ADS)

    Sunaguchi, Naoki; Yuasa, Tetsuya; Huo, Qingkai; Ichihara, Shu; Ando, Masami

    2011-09-01

    A soft tissue tomosynthesis imaging system using Laue-case analyzer for dark-field imaging (DFI) optics is described. Two images from which refraction component is deduced are obtained in a single exposure of DFI, while two exposures are required in diffraction enhanced imaging (DEI). The measurement time and radiation dose are thus reduced to half those from DEI. Additionally, the proposed reconstruction algorithm, using only one tenth the number of projections required in computed tomography (CT) imaging, produced images in no way inferior to refraction-contrast CT images. We ex vivo imaged an excised human lung tissue using the system constructed at the KEK vertical wiggler beamline PF-BL14C to demonstrate the proposed imaging protocol efficacy.

  20. Dark-field hyperspectral X-ray imaging

    PubMed Central

    Egan, Christopher K.; Jacques, Simon D. M.; Connolley, Thomas; Wilson, Matthew D.; Veale, Matthew C.; Seller, Paul; Cernik, Robert J.

    2014-01-01

    In recent times, there has been a drive to develop non-destructive X-ray imaging techniques that provide chemical or physical insight. To date, these methods have generally been limited; either requiring raster scanning of pencil beams, using narrow bandwidth radiation and/or limited to small samples. We have developed a novel full-field radiographic imaging technique that enables the entire physio-chemical state of an object to be imaged in a single snapshot. The method is sensitive to emitted and scattered radiation, using a spectral imaging detector and polychromatic hard X-radiation, making it particularly useful for studying large dense samples for materials science and engineering applications. The method and its extension to three-dimensional imaging is validated with a series of test objects and demonstrated to directly image the crystallographic preferred orientation and formed precipitates across an aluminium alloy friction stir weld section. PMID:24808753

  1. Enzyme catalysis enhanced dark-field imaging as a novel immunohistochemical method

    NASA Astrophysics Data System (ADS)

    Fan, Lin; Tian, Yanyan; Yin, Rong; Lou, Doudou; Zhang, Xizhi; Wang, Meng; Ma, Ming; Luo, Shouhua; Li, Suyi; Gu, Ning; Zhang, Yu

    2016-04-01

    Conventional immunohistochemistry is limited to subjective judgment based on human experience and thus it is clinically required to develop a quantitative immunohistochemical detection. 3,3'-Diaminobenzidin (DAB) aggregates, a type of staining product formed by conventional immunohistochemistry, were found to have a special optical property of dark-field imaging for the first time, and the mechanism was explored. On this basis, a novel immunohistochemical method based on dark-field imaging for detecting HER2 overexpressed in breast cancer was established, and the quantitative analysis standard and relevant software for measuring the scattering intensity was developed. In order to achieve a more sensitive detection, the HRP (horseradish peroxidase)-labeled secondary antibodies conjugated gold nanoparticles were constructed as nanoprobes to load more HRP enzymes, resulting in an enhanced DAB deposition as a dark-field label. Simultaneously, gold nanoparticles also act as a synergistically enhanced agent due to their mimicry of enzyme catalysis and dark-field scattering properties.Conventional immunohistochemistry is limited to subjective judgment based on human experience and thus it is clinically required to develop a quantitative immunohistochemical detection. 3,3'-Diaminobenzidin (DAB) aggregates, a type of staining product formed by conventional immunohistochemistry, were found to have a special optical property of dark-field imaging for the first time, and the mechanism was explored. On this basis, a novel immunohistochemical method based on dark-field imaging for detecting HER2 overexpressed in breast cancer was established, and the quantitative analysis standard and relevant software for measuring the scattering intensity was developed. In order to achieve a more sensitive detection, the HRP (horseradish peroxidase)-labeled secondary antibodies conjugated gold nanoparticles were constructed as nanoprobes to load more HRP enzymes, resulting in an enhanced DAB

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

    SciTech Connect

    Sunaguchi, Naoki; Yuasa, Tetsuya; Huo, Qingkai; Ichihara, Shu; Ando, Masami

    2010-10-11

    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.

  3. On Detailed Contrast of Biomedical Object in X-ray Dark-Field Imaging

    SciTech Connect

    Shimao, Daisuke; Mori, Koichi; Sugiyama, Hiroshi; Kunisada, Toshiyuki; Hyodo, Kazuyuki; Ando, Masami

    2007-01-19

    Over the past 10 years, refraction-based X-ray imaging has been studied together with a perspective view to clinical application. X-ray Dark-Field Imaging that utilizes a Laue geometry analyzer has recently been proposed and has the proven ability to depict articular cartilage in an intact human finger. In the current study, we researched detailed image contrast using X-ray Dark-Field Imaging by observing the edge contrast of an acrylic rod as a simple case, and found differences in image contrast between the right and left edges of the rod. This effect could cause undesirable contrast in the thin articular cartilage on the head of the phalanx. To avoid overlapping with this contrast at the articular cartilage, which would lead to a wrong diagnosis, we suggest that a joint surface on which articular cartilage is located should be aligned in the same sense as the scattering vector of the Laue case analyzer crystal. Defects of articular cartilage were successfully detected under this condition. When utilized under appropriate imaging conditions, X-ray Dark-Field Imaging will be a powerful tool for the diagnosis of arthropathy, as minute changes in articular cartilage may be early-stage features of this disease.

  4. The effect of Sb-surfactant on GaInP CuPtB type ordering: assessment through dark field TEM and aberration corrected HAADF imaging.

    PubMed

    Coll, C; Barrigón, E; López-Conesa, L; Rebled, J; Barrutia, L; Rey-Stolle, I; Estradé, S; Algora, C; Peiró, F

    2017-04-03

    We report on the effect of Sb on the microstructure of GaInP layers grown by metal organic vapor phase epitaxy (MOVPE). These layers exhibit a CuPtB single variant ordering due to the intentional misorientation of the substrate (Ge(001) substrates with 6° misorientation towards the nearest [111] axis). The use of Sb as a surfactant during the GaInP growth does not modify the type of ordering, but it is found that the order parameter (η) decreases with increasing Sb flux. Dark field microscopy reveals a variation of the angle of the antiphase boundaries (APBs) with Sb amount. The microstructure is assessed through high angle annular dark field (HAADF) experiments and image simulation revealing Z-contrast loss in APBs due to the superposition of ordered domains.

  5. Tissue Visualization Using X-Ray Dark-Field Imaging towards Pathological Goal

    NASA Astrophysics Data System (ADS)

    Ando, Masami; Chikaura, Yoshinori; Endo, Tokiko; Gupta, Rajiv; Huo, Qingkai; Hyodo, Kazuyuki; Ichihara, Shu; Mori, Kensaku; Nakao, Yuki; Ohura, Norihiko; Sunaguchi, Naoki; Sugiyama, Hiroshi; Suzuki, Yoshifumi; Wu, Yanlin; Yuasa, Tetsuya; Xiaowei, Zhang

    2013-03-01

    In XDFI (x-ray dark-field imaging) LAA (Laue-case angle analyzer) simultaneously provides two x-ray images; one corresponds to a FD forward diffracted beam and a separate D diffracted beam. When this is applied to biomedical specimens x-ray images are very high contrast and very high spatial resolution. We constructed XDFI system at the vertical wiggler beamline BL-14C in KEK Photon Factory and performed imaging experiment of breast tissues and an excised human femoral artery. In this paper, we discuss a tissue visualization and pathological goal using 2D, 3D-CT and 2.5D image (tomosynthesis) with XDFI.

  6. Intergrowth structure of α-phase in β-type TmAlB{sub 4} compound studied by high-angle annular detector dark-field scanning transmission electron microscopy

    SciTech Connect

    Yubuta, Kunio; Mori, Takao; Leithe-Jasper, Andreas; Borrmann, Horst; Grin, Yuri; Okada, Shigeru; Shishido, Toetsu

    2014-11-15

    Nanostructure of a ThMoB{sub 4}-type (β-type) TmAlB{sub 4} compound, in which YCrB{sub 4}-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-TmAlB{sub 4} 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 ThMoB{sub 4}-type (β-type) TmAlB{sub 4} compound, in which YCrB{sub 4}-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.

  7. Advanced contrast modalities for X-ray radiology: Phase-contrast and dark-field imaging using a grating interferometer.

    PubMed

    Bech, Martin; Jensen, Torben H; Bunk, Oliver; Donath, Tilman; David, Christian; Weitkamp, Timm; Le Duc, Geraldine; Bravin, Alberto; Cloetens, Peter; Pfeiffer, Franz

    2010-01-01

    Here we review our recent progress in the field of X-ray dark-field and phase-contrast imaging using a grating interferometer. We describe the basic imaging principles of grating-based phase-contrast and dark-field radiography and present some exemplary results obtained for simple test objects and biological specimens. Furthermore, we discuss how phase-contrast and dark-field radiography can be combined with the concept of computed tomography, and yield highly detailed three-dimensional insights into biomedical sample. Exemplary results obtained with standard X-ray tube sources and highly brilliant synchrotron sources are presented.

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

    PubMed Central

    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

  9. Coherent total internal reflection dark-field microscopy: label-free imaging beyond the diffraction limit.

    PubMed

    von Olshausen, Philipp; Rohrbach, Alexander

    2013-10-15

    Coherent imaging is barely applicable in life-science microscopy due to multiple interference artifacts. Here, we show how these interferences can be used to improve image resolution and contrast. We present a dark-field microscopy technique with evanescent illumination via total internal reflection that delivers high-contrast images of coherently scattering samples. By incoherent averaging of multiple coherent images illuminated from different directions we can resolve image structures that remain unresolved by conventional (incoherent) fluorescence microscopy. We provide images of 190 nm beads revealing resolution beyond the diffraction limit and slightly increased object distances. An analytical model is introduced that accounts for the observed effects and which is confirmed by numerical simulations. Our approach may be a route to fast, label-free, super-resolution imaging in live-cell microscopy.

  10. Noninvasive assessment of the iridial microcirculation in rats using sidestream dark field imaging.

    PubMed

    Cerny, V; Zhou, J; Kelly, M; Alotibi, I; Turek, Z; Whynot, S; Saleh, I Abdo; Lehmann, C

    2013-02-01

    Sidestream dark field imaging represents a novel, noninvasive method to study the microcirculation in humans and animals. To-date, it has been used extensively in various peripheral tissues (e.g. sublingual area, intestinal mucosa), however no data for the ocular vasculature, including the iridial microcirculation, are currently available. Therefore, the aim of this study was to examine the reliability and reproducibility of sidestream dark field imaging within the iridial microcirculation in experimental animals. Male Lewis rats were anaesthetized and the iris microvasculature was observed using an sidestream dark field probe gently placed against a cover slip covering the right eye. All video sequences recorded were analysed off-line by using AVA 3.0 software (MicroVision Medical, Amsterdam, The Netherlands). Results are expressed as mean (±SE) or median (interquartile range). Clear images were recorded from each animal and the total number of analysable video sequences was 50. All raw data for selected vessel density parameters passed normality test. The total all and small vessel density (in mm mm(-2) ) were 22,6 (±0,58) and 19,6 (±0,68), respectively. The perfused all and small vessel density were 20,9 (±0,61) and 19,1 (±0,65), respectively. The mean values of all iris vessel density parameters are shown in Figure 4. The DeBacker Score (n/mm) was 15,2 (±0,45), the proportion of perfused vessel was 94,5% (89,8-99,1%), and the MFI was 3 points (3-3). Taken together, these results indicate that SDF imaging provides a reliable and noninvasive method to examine the iridial microvascular bed in vivo and, thus, may provide unique opportunities for the study of the iridial vascular network in various experimental and clinical settings and disease models.

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

    PubMed

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

    2016-07-28

    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.

  12. Dark-field image contrast in transmission scanning electron microscopy: Effects of substrate thickness and detector collection angle.

    PubMed

    Woehl, Taylor; Keller, Robert

    2016-12-01

    An annular dark field (ADF) detector was placed beneath a specimen in a field emission scanning electron microscope operated at 30kV to calibrate detector response to incident beam current, and to create transmission images of gold nanoparticles on silicon nitride (SiN) substrates of various thicknesses. Based on the linear response of the ADF detector diodes to beam current, we developed a method that allowed for direct determination of the percentage of that beam current forward scattered to the ADF detector from the sample, i.e. the transmitted electron (TE) yield. Collection angles for the ADF detector region were defined using a masking aperture above the detector and were systematically varied by changing the sample to detector distance. We found the contrast of the nanoparticles, relative to the SiN substrate, decreased monotonically with decreasing inner exclusion angle and increasing substrate thickness. We also performed Monte Carlo electron scattering simulations, which showed quantitative agreement with experimental contrast associated with the nanoparticles. Together, the experiments and Monte Carlo simulations revealed that the decrease in contrast with decreasing inner exclusion angle was due to a rapid increase in the TE yield of the low atomic number substrate. Nanoparticles imaged at low inner exclusion angles (<150mrad) and on thick substrates (>50nm) showed low image contrast in their centers surrounded by a bright high-contrast halo on their edges. This complex image contrast was predicted by Monte Carlo simulations, which we interpreted in terms of mixing of the nominally bright field (BF) and ADF electron signals. Our systematic investigation of inner exclusion angle and substrate thickness effects on ADF t-SEM imaging provides fundamental understanding of the contrast mechanisms for image formation, which in turn suggest practical limitations and optimal imaging conditions for different substrate thicknesses.

  13. A dark-field scanning spectroscopy platform for localized scatter and fluorescence imaging of tissue

    NASA Astrophysics Data System (ADS)

    Krishnaswamy, Venkataramanan; Laughney, Ashley M.; Paulsen, Keith D.; Pogue, Brian W.

    2011-03-01

    Tissue ultra-structure and molecular composition provide native contrast mechanisms for discriminating across pathologically distinct tissue-types. Multi-modality optical probe designs combined with spatially confined sampling techniques have been shown to be sensitive to this type of contrast but their extension to imaging has only been realized recently. A modular scanning spectroscopy platform has been developed to allow imaging localized morphology and molecular contrast measures in breast cancer surgical specimens. A custom designed dark-field telecentric scanning spectroscopy system forms the core of this imaging platform. The system allows imaging localized elastic scatter and fluorescence measures over fields of up to 15 mm x 15 mm at 100 microns resolution in tissue. Results from intralipid and blood phantom measurements demonstrate the ability of the system to quantify localized scatter parameters despite significant changes in local absorption. A co-registered fluorescence spectroscopy mode is also demonstrated in a protophorphyrin-IX phantom.

  14. A Dark-field Scanning In Situ Spectroscopy Platform for Broadband Imaging of Resected Tissue

    PubMed Central

    Krishnaswamy, Venkataramanan; Laughney, Ashley M.; Paulsen, Keith D.; Pogue, Brian W.

    2012-01-01

    A dark-field geometry spectral imaging system is presented to raster-scan thick tissue samples in situ in 1.5cm square sections, recovering full spectra from each 100 microns diameter pixel. This spot size provides adequate resolution for wide field scanning, while also facilitating scatter imaging without requiring sophisticated light-tissue transport modeling. The system is demonstrated showing accurate estimation of localized scatter parameters and the potential to recover absorption-based contrast from broadband reflectance data measured from 480nm up to 750nm in tissue phantoms. Results obtained from xenograft pancreas tumors show the ability to quantitatively image changes in localized scatter response in this fast imaging geometry. The polychromatic raster scan design allows the rapid scanning necessary for use in surgical/clinical applications where timely decisions are required about tissue pathology. PMID:21593932

  15. Dark-field spectral imaging microscope for localized surface plasmon resonance-based biosensing

    NASA Astrophysics Data System (ADS)

    Yim, Sang-Youp; Park, Jin-Ho; Kim, Min-Gon

    2015-07-01

    Localized surface plasmon resonance (LSPR) of metal nanoparticles makes red-shift of extinction wavelength with an increase in the refractive index at the surface of the metal nanoparticles. Since biomolecules bound to the metal nanoparticle's surface induce refractive index change, biosensing based on LSPR effect can be possible by monitoring scattering or absorption spectrum changes. Generally, however, conventional method detects ensemble averaged LSPR signal of a huge number of metal nanoparticles. Here, we have constructed a dark-field spectral imaging microscope in order to monitor the scattering spectra of individual metal nanoparticles, simultaneously. Gold nanorod (GNR) and aptamer are employed to detect ochratoxin A (OTA) related to a carcinogenic illness. An aptamer-target binding mechanism promotes wavelength shift of extinction spectra due to refractive index change within sensing volume of GNR by structural change of aptamer. A number of GNRs can be identified in a dark-field LSPR image, simultaneously. A typical spectrum of a GNR exhibits red-shift after target binding of molecules and OTA detection is extended to the very low concentration of 1 pM level.

  16. General solution for quantitative dark-field contrast imaging with grating interferometers

    NASA Astrophysics Data System (ADS)

    Strobl, M.

    2014-11-01

    Grating interferometer based imaging with X-rays and neutrons has proven to hold huge potential for applications in key research fields conveying biology and medicine as well as engineering and magnetism, respectively. The thereby amenable dark-field imaging modality implied the promise to access structural information beyond reach of direct spatial resolution. However, only here a yet missing approach is reported that finally allows exploiting this outstanding potential for non-destructive materials characterizations. It enables to obtain quantitative structural small angle scattering information combined with up to 3-dimensional spatial image resolution even at lab based x-ray or at neutron sources. The implied two orders of magnitude efficiency gain as compared to currently available techniques in this regime paves the way for unprecedented structural investigations of complex sample systems of interest for material science in a vast range of fields.

  17. Three-dimensional shapes and distribution of FePd nanoparticles observed by electron tomography using high-angle annular dark-field scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Sato, Kazuhisa; Aoyagi, Kenta; Konno, Toyohiko J.

    2010-01-01

    We have studied three-dimensional shapes and distribution of FePd nanoparticles, prepared by electron beam deposition and postdeposition annealing, by means of single-axis tilt tomography using atomic number contrasts obtained by high-angle annular dark-field scanning transmission electron microscopy. Particle size, shape, and locations were reconstructed by weighted backprojection (WBP), as well as by simultaneous iterative reconstruction technique (SIRT). We have also estimated the particle size by simple extrapolation of tilt-series original data sets, which proved to be quite powerful. The results of the two algorithms for reconstruction have been compared quantitatively with those obtained by the extrapolation method and those independently reported by electron holography. It was found that the reconstructed intensity map by WBP contains a small amount of dotlike artifacts, which do not exist in the results by SIRT, and that the particle surface obtained by WBP is rougher than that by SIRT. We demonstrate, on the other hand, that WBP yields a better estimation of the particle size in the z direction than SIRT does, most likely due to the presence of a "missing wedge" in the original data set.

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

    NASA Astrophysics Data System (ADS)

    Sunaguchi, N.; Yuasa, T.; Ichihara, S.; Huo, Q.; Sakai, M.; Wu, Y.; Shimao, D.; Ando, M.

    2013-03-01

    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.

  19. High Quality Image Formation by Nonlocal Means Applied to High-Angle Annular Darkfield Scanning Transmission Electron Microscopy (HAADF-STEM)

    DTIC Science & Technology

    2010-12-31

    sample enables certain electron imaging and spectroscopic techniques such as mapping by energy dispersive X-ray (EDX) spectroscopy , electron energy...loss spectroscopy (EELS) and annular dark-field imaging (ADF). These signals can be obtained simultane- ously, allowing direct correlation of image and...spectroscopic data. By using a STEM and a high-angle annular detector, it is possible to obtain atomic resolution images where the contrast is

  20. High-contrast multilayer imaging of biological organisms through dark-field digital refocusing

    NASA Astrophysics Data System (ADS)

    Faridian, Ahmad; Pedrini, Giancarlo; Osten, Wolfgang

    2013-08-01

    We have developed an imaging system to extract high contrast images from different layers of biological organisms. Utilizing a digital holographic approach, the system works without scanning through layers of the specimen. In dark-field illumination, scattered light has the main contribution in image formation, but in the case of coherent illumination, this creates a strong speckle noise that reduces the image quality. To remove this restriction, the specimen has been illuminated with various speckle-fields and a hologram has been recorded for each speckle-field. Each hologram has been analyzed separately and the corresponding intensity image has been reconstructed. The final image has been derived by averaging over the reconstructed images. A correlation approach has been utilized to determine the number of speckle-fields required to achieve a desired contrast and image quality. The reconstructed intensity images in different object layers are shown for different sea urchin larvae. Two multimedia files are attached to illustrate the process of digital focusing.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Orientation-selective X-ray dark field imaging of ordered systems

    NASA Astrophysics Data System (ADS)

    Revol, V.; Kottler, C.; Kaufmann, R.; Neels, A.; Dommann, A.

    2012-12-01

    X-ray scatter dark field imaging with a grating interferometer is becoming a standard tool for the characterization of microscopic texture of samples. Recently, it was shown that directional information could also be recovered when the sample displays an anisotropic ordering such as, for instance, a bundle of microscopic fibers. Here, we demonstrate that previously suggested approaches are ambiguous when multiple anisotropic orientations coexist in the sample. Therefore, we developed a new orientation-selective approach which allows for separating the contributions of individual orientations provided that these orientations are known a-priori. The method, demonstrated experimentally using a well-defined wood sample, is envisioned to be of high interest for the non-destructive inspection of composite materials.

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

    PubMed Central

    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

  4. Refraction-based X-ray Computed Tomography for Biomedical Purpose Using Dark Field Imaging Method

    NASA Astrophysics Data System (ADS)

    Sunaguchi, Naoki; Yuasa, Tetsuya; Huo, Qingkai; Ichihara, Shu; Ando, Masami

    We have proposed a tomographic x-ray imaging system using DFI (dark field imaging) optics along with a data-processing method to extract information on refraction from the measured intensities, and a reconstruction algorithm to reconstruct a refractive-index field from the projections generated from the extracted refraction information. The DFI imaging system consists of a tandem optical system of Bragg- and Laue-case crystals, a positioning device system for a sample, and two CCD (charge coupled device) cameras. Then, we developed a software code to simulate the data-acquisition, data-processing, and reconstruction methods to investigate the feasibility of the proposed methods. Finally, in order to demonstrate its efficacy, we imaged a sample with DCIS (ductal carcinoma in situ) excised from a breast cancer patient using a system constructed at the vertical wiggler beamline BL-14C in KEK-PF. Its CT images depicted a variety of fine histological structures, such as milk ducts, duct walls, secretions, adipose and fibrous tissue. They correlate well with histological sections.

  5. Microbubbles as a scattering contrast agent for grating-based x-ray dark-field imaging.

    PubMed

    Velroyen, A; Bech, M; Malecki, A; Tapfer, A; Yaroshenko, A; Ingrisch, M; Cyran, C C; Auweter, S D; Nikolaou, K; Reiser, M; Pfeiffer, F

    2013-02-21

    In clinically established-absorption-based-biomedical x-ray imaging, contrast agents with high atomic numbers (e.g. iodine) are commonly used for contrast enhancement. The development of novel x-ray contrast modalities such as phase contrast and dark-field contrast opens up the possible use of alternative contrast media in x-ray imaging. We investigate using ultrasound contrast agents, which unlike iodine-based contrast agents can also be administered to patients with renal impairment and thyroid dysfunction, for application with a recently developed novel x-ray dark-field imaging modality. To produce contrast from these microbubble-based contrast agents, our method exploits ultra-small-angle coherent x-ray scattering. Such scattering dark-field x-ray images can be obtained with a grating-based x-ray imaging setup, together with refraction-based differential phase-contrast and the conventional attenuation contrast images. In this work we specifically show that ultrasound contrast agents based on microbubbles can be used to produce strongly enhanced dark-field contrast, with superior contrast-to-noise ratio compared to the attenuation signal. We also demonstrate that this method works well with an x-ray tube-based setup and that the relative contrast gain even increases when the pixel size is increased from tenths of microns to clinically compatible detector resolutions about up to a millimetre.

  6. Microbubbles as a scattering contrast agent for grating-based x-ray dark-field imaging

    NASA Astrophysics Data System (ADS)

    Velroyen, A.; Bech, M.; Malecki, A.; Tapfer, A.; Yaroshenko, A.; Ingrisch, M.; Cyran, C. C.; Auweter, S. D.; Nikolaou, K.; Reiser, M.; Pfeiffer, F.

    2013-02-01

    In clinically established—absorption-based—biomedical x-ray imaging, contrast agents with high atomic numbers (e.g. iodine) are commonly used for contrast enhancement. The development of novel x-ray contrast modalities such as phase contrast and dark-field contrast opens up the possible use of alternative contrast media in x-ray imaging. We investigate using ultrasound contrast agents, which unlike iodine-based contrast agents can also be administered to patients with renal impairment and thyroid dysfunction, for application with a recently developed novel x-ray dark-field imaging modality. To produce contrast from these microbubble-based contrast agents, our method exploits ultra-small-angle coherent x-ray scattering. Such scattering dark-field x-ray images can be obtained with a grating-based x-ray imaging setup, together with refraction-based differential phase-contrast and the conventional attenuation contrast images. In this work we specifically show that ultrasound contrast agents based on microbubbles can be used to produce strongly enhanced dark-field contrast, with superior contrast-to-noise ratio compared to the attenuation signal. We also demonstrate that this method works well with an x-ray tube-based setup and that the relative contrast gain even increases when the pixel size is increased from tenths of microns to clinically compatible detector resolutions about up to a millimetre.

  7. Dark field optical imaging reveals vascular changes in an inducible hamster cheek pouch model during carcinogenesis

    PubMed Central

    Hu, Fangyao; Morhard, Robert; Murphy, Helen A.; Zhu, Caigang; Ramanujam, Nimmi

    2016-01-01

    In this study, we propose a low-cost cross-polarized dark field microscopy system for in vivo vascular imaging to detect head and neck cancer. A simple-to-use Gabor-filter-based image processing technique was developed to objectively and automatically quantify several important vascular features, including tortuosity, length, diameter and area fraction, from vascular images. Simulations were performed to evaluate the accuracies of vessel segmentation and feature extraction for our algorithm. Sensitivity and specificity for vessel segmentation of the Gabor masks both remained above 80% at all contrast levels when compared to gold-standard masks. Errors for vascular feature extraction were under 5%. Moreover, vascular contrast and vessel diameter were identified to be the two primary factors which affected the segmentation accuracies. After our algorithm was validated, we monitored the blood vessels in an inducible hamster cheek pouch carcinogen model over 17 weeks and quantified vascular features during carcinogenesis. A significant increase in vascular tortuosity and a significant decrease in vessel length were observed during carcinogenesis. PMID:27699096

  8. Frequency-Induced Bulk Magnetic Domain-Wall Freezing Visualized by Neutron Dark-Field Imaging

    NASA Astrophysics Data System (ADS)

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

    2016-08-01

    We use neutron dark-field imaging to visualize and interpret the response of bulk magnetic domain walls to static and dynamic magnetic excitations in (110)-Goss textured iron silicon high-permeability steel alloy. We investigate the domain-wall motion under the influence of an external alternating sinusoidal magnetic field. In particular, we perform scans combining varying levels of dcoffset (0 - 30 A /m ) , oscillation amplitude Aac (0 - 1500 A /m ) , and frequency fac ((0 - 200 Hz ) . By increasing amplitude Aac while maintaining constant values of dcoffset and fac , we record the transition from a frozen domain-wall structure to a mobile one. Vice versa, increasing fac while keeping Aac and dcoffset constant led to the reverse transition from a mobile domain-wall structure into a frozen one. We show that varying both Aac and fac shifts the position of the transition region. Furthermore, we demonstrate that higher frequencies require higher oscillation amplitudes to overcome the freezing phenomena. The fundamental determination and understanding of the frequency-induced freezing process in high-permeability steel alloys is of high interest to the further development of descriptive models for bulk macromagnetic phenomena. Likewise, the efficiency of transformers can be improved based on our results, since these alloys are used as transformer core material.

  9. Determination of Bulk Magnetic Volume Properties by Neutron Dark-Field Imaging

    NASA Astrophysics Data System (ADS)

    Grünzweig, Christian; Siebert, René; Betz, Benedikt; Rauscher, Peter; Schäfer, Rudolf; Lehmann, Eberhard

    For the production of high-class electrical steel grades a deeper understanding of the magnetic domain interaction with induced mechanical stresses is strongly required. This holds for non-oriented (NO) as well as grain-oriented (GO) steels. In the case of non-oriented steels the magnetic property degeneration after punching or laser cutting is essential for selecting correct obstructing material grades and designing efficient electrical machines. Until now these effects stay undiscovered due to the lack of adequate investigation methods that reveal local bulk information on processed laminations. Here we show how the use of a non-destructive testing method based on a neutron grating interferometry providing the dark-field image contrast delivers spatially-resolved transmission information about the local bulk domain arrangement and domain wall density. With the help of this technique it is possible to visualize magnetization processes within the NO laminations. Different representative manufacturing techniques are compared in terms of magnetic flux density deterioration such as punching, mechanically cutting by guillotine as well as laser fusion cutting using industrial high power laser beam sources. For GO steel laminations the method is applicable on the one hand to visualize the internal domain structure without being hindered by the coating layer. On the other hand, we can show the influence of the coating layer onto the underlying domain structure.

  10. Speckle-Based X-Ray Phase-Contrast and Dark-Field Imaging with a Laboratory Source

    NASA Astrophysics Data System (ADS)

    Zanette, I.; Zhou, T.; Burvall, A.; Lundström, U.; Larsson, D. H.; Zdora, M.; Thibault, P.; Pfeiffer, F.; Hertz, H. M.

    2014-06-01

    We report on the observation and application of near-field speckles with a laboratory x-ray source. The detection of speckles is possible thanks to the enhanced brilliance properties of the used liquid-metal-jet source, and opens the way to a range of new applications in laboratory-based coherent x-ray imaging. Here, we use the speckle pattern for multimodal imaging of demonstrator objects. Moreover, we introduce algorithms for phase and dark-field imaging using speckle tracking, and we show that they yield superior results with respect to existing methods.

  11. Simulation of dark-field imaging of micro-calcifications in human breast tissue with X-ray Talbot-Lau interferometry

    NASA Astrophysics Data System (ADS)

    Ritter, A.; Anton, G.; Bayer, F.; Gödel, K.; Pelzer, G.; Rieger, J.; Weber, T.; Zang, A.; Michel, T.

    2014-05-01

    A simulation of dark-field imaging of sub-resolution structures with X-ray Talbot-Lau interferometry is presented. Data obtained from the simulation shows good agreement to a signal found in the dark-field image of a surgically removed sample of human breast tissue containing micro calcifications. A measure for the type of micro calcifications is introduced which can be calculated from dark-field signals. In a further analysis of the simulated data, it can be shown that the measure can be used to discriminate between different calcifications types.

  12. Ex Vivo Perfusion-Simulation Measurements of Microbubbles as a Scattering Contrast Agent for Grating-Based X-Ray Dark-Field Imaging.

    PubMed

    Velroyen, Astrid; Bech, Martin; Tapfer, Arne; Yaroshenko, Andre; Müller, Mark; Paprottka, Philipp; Ingrisch, Michael; Cyran, Clemens C; Auweter, Sigrid D; Nikolaou, Konstantin; Reiser, Maximilian F; Pfeiffer, Franz

    2015-01-01

    The investigation of dedicated contrast agents for x-ray dark-field imaging, which exploits small-angle scattering at microstructures for contrast generation, is of strong interest in analogy to the common clinical use of high-atomic number contrast media in conventional attenuation-based imaging, since dark-field imaging has proven to provide complementary information. Therefore, agents consisting of gas bubbles, as used in ultrasound imaging for example, are of particular interest. In this work, we investigate an experimental contrast agent based on microbubbles consisting of a polyvinyl-alcohol shell with an iron oxide coating, which was originally developed for multimodal imaging and drug delivery. Its performance as a possible contrast medium for small-animal angiography was examined using a mouse carcass to realistically consider attenuating and scattering background signal. Subtraction images of dark field, phase contrast and attenuation were acquired for a concentration series of 100%, 10% and 1.3% to mimic different stages of dilution in the contrast agent in the blood vessel system. The images were compared to the gold-standard iodine-based contrast agent Solutrast, showing a good contrast improvement by microbubbles in dark-field imaging. This study proves the feasibility of microbubble-based dark-field contrast-enhancement in presence of scattering and attenuating mouse body structures like bone and fur. Therefore, it suggests a strong potential of the use of polymer-based microbubbles for small-animal dark-field angiography.

  13. Granuloma annulare - close-up (image)

    MedlinePlus

    Granuloma annulare is usually a self-limiting disorder characterized by raised lesions arranged in an annular shape. ... This picture shows a close-up of a granuloma annulare that is subcutaneous (deeper). It demonstrates the ...

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

    NASA Astrophysics Data System (ADS)

    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

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

    SciTech Connect

    Zdora, Marie-Christine; Thibault, Pierre; Pfeiffer, Franz; Zanette, Irene

    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.

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

    NASA Astrophysics Data System (ADS)

    Zdora, Marie-Christine; Thibault, Pierre; Pfeiffer, Franz; Zanette, Irene

    2015-09-01

    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.

  17. A noise reduction method for quantifying nanoparticle light scattering in low magnification dark-field microscope far-field images

    PubMed Central

    Sun, Dali

    2016-01-01

    Nanoparticles have become a powerful tool for cell imaging, biomolecule and cell and protein interaction studies, but are difficult to rapidly and accurately measure in most assays. Dark-field microscope (DFM) image analysis approaches used to quantify nanoparticles require high-magnification near-field (HN) images that are labor intensive due to a requirement for manual image selection and focal adjustments needed when identifying and capturing new regions of interest. Low-magnification far-field (LF) DFM imagery is technically simpler to perform but cannot be used as an alternate to HN-DFM quantification, since it is highly sensitive to surface artifacts and debris that can easily mask nanoparticle signal. We now describe a new noise reduction approach that markedly reduces LF-DFM image artifacts to allow sensitive and accurate nanoparticle signal quantification from LF-DFM images. We have used this approach to develop a “Dark Scatter Master” (DSM) algorithm for the popular NIH image analysis program ImageJ, which can be readily adapted for use with automated high-throughput assay analyses. This method demonstrated robust performance quantifying nanoparticles in different assay formats, including a novel method that quantified extracellular vesicles in patient blood sample to detect pancreatic cancer cases. Based on these results, we believe our LF-DFM quantification method can markedly decrease the analysis time of most nanoparticle-based assays to impact both basic research and clinical analyses. PMID:28177210

  18. In situ assessment of the renal microcirculation in mechanically ventilated rats using sidestream dark-field imaging.

    PubMed

    Astapenko, D; Jor, O; Lehmann, C; Cerny, V

    2015-02-01

    For microcirculation research there is a need for baseline data and feasibility protocols describing microcirculation of various organs. The aim of our study was to examine the reliability and reproducibility of sidestream dark-field (SDF) imaging within the renal cortical microcirculation in rats. Renal microcirculation was observed using SDF probe placed on the exposed renal surface via the upper midline laparotomy. Video sequences recorded intermittently in short apneic pauses were analyzed off-line by using AVA 3.0 software (MicroVision Medical, Amsterdam, the Netherlands). Results are expressed as mean (SD) or median (25-75% percentiles). We obtained 60 clear sequences from all recorded analyzable videos from all the animals. The total small vessel and all vessel density (in mm.mm(-2) ) were (28.79 ± 0.40) and (28.95 ± 0.40), respectively. The perfused small and all vessel density were (28.79 ± 0.40) and (28.95 ± 0.40), respectively. The DeBacker Score was (19.14 ± 0.43), the proportion of perfused vessels was 100% (100-100%) and the microvascular flow index was 3.49 (3-3.75). We conclude SDF imaging provides a reliable method to examine the renal microvascular bed in vivo and thus can be used for the study of the renal cortical vascular network in various experimental diseases models and clinical settings.

  19. Dark-field phase retrieval under the constraint of the Friedel symmetry in coherent X-ray diffraction imaging.

    PubMed

    Kobayashi, Amane; Sekiguchi, Yuki; Takayama, Yuki; Oroguchi, Tomotaka; Nakasako, Masayoshi

    2014-11-17

    Coherent X-ray diffraction imaging (CXDI) is a lensless imaging technique that is suitable for visualizing the structures of non-crystalline particles with micrometer to sub-micrometer dimensions from material science and biology. One of the difficulties inherent to CXDI structural analyses is the reconstruction of electron density maps of specimen particles from diffraction patterns because saturated detector pixels and a beam stopper result in missing data in small-angle regions. To overcome this difficulty, the dark-field phase-retrieval (DFPR) method has been proposed. The DFPR method reconstructs electron density maps from diffraction data, which are modified by multiplying Gaussian masks with an observed diffraction pattern in the high-angle regions. In this paper, we incorporated Friedel centrosymmetry for diffraction patterns into the DFPR method to provide a constraint for the phase-retrieval calculation. A set of model simulations demonstrated that this constraint dramatically improved the probability of reconstructing correct electron density maps from diffraction patterns that were missing data in the small-angle region. In addition, the DFPR method with the constraint was applied successfully to experimentally obtained diffraction patterns with significant quantities of missing data. We also discuss this method's limitations with respect to the level of Poisson noise in X-ray detection.

  20. A first investigation of accuracy, precision and sensitivity of phase-based x-ray dark-field imaging

    NASA Astrophysics Data System (ADS)

    Astolfo, Alberto; Endrizzi, Marco; Kallon, Gibril; Millard, Thomas P.; Vittoria, Fabio A.; Olivo, Alessandro

    2016-12-01

    In the last two decades, x-ray phase contrast imaging (XPCI) has attracted attention as a potentially significant improvement over widespread and established x-ray imaging. The key is its capability to access a new physical quantity (the ‘phase shift’), which can be complementary to x-ray absorption. One additional advantage of XPCI is its sensitivity to micro structural details through the refraction induced dark-field (DF). While DF is extensively mentioned and used for several applications, predicting the capability of an XPCI system to retrieve DF quantitatively is not straightforward. In this article, we evaluate the impact of different design options and algorithms on DF retrieval for the edge-illumination (EI) XPCI technique. Monte Carlo simulations, supported by experimental data, are used to measure the accuracy, precision and sensitivity of DF retrieval performed with several EI systems based on conventional x-ray sources. The introduced tools are easy to implement, and general enough to assess the DF performance of systems based on alternative (i.e. non-EI) XPCI approaches.

  1. In-vivo dark-field and phase-contrast x-ray imaging.

    PubMed

    Bech, M; Tapfer, A; Velroyen, A; Yaroshenko, A; Pauwels, B; Hostens, J; Bruyndonckx, P; Sasov, A; Pfeiffer, F

    2013-11-13

    Novel radiography approaches based on the wave nature of x-rays when propagating through matter have a great potential for improved future x-ray diagnostics in the clinics. Here, we present a significant milestone in this imaging method: in-vivo multi-contrast x-ray imaging of a mouse using a compact scanner. Of particular interest is the enhanced contrast in regions related to the respiratory system, indicating a possible application in diagnosis of lung diseases (e.g. emphysema).

  2. In-vivo dark-field and phase-contrast x-ray imaging

    NASA Astrophysics Data System (ADS)

    Bech, M.; Tapfer, A.; Velroyen, A.; Yaroshenko, A.; Pauwels, B.; Hostens, J.; Bruyndonckx, P.; Sasov, A.; Pfeiffer, F.

    2013-11-01

    Novel radiography approaches based on the wave nature of x-rays when propagating through matter have a great potential for improved future x-ray diagnostics in the clinics. Here, we present a significant milestone in this imaging method: in-vivo multi-contrast x-ray imaging of a mouse using a compact scanner. Of particular interest is the enhanced contrast in regions related to the respiratory system, indicating a possible application in diagnosis of lung diseases (e.g. emphysema).

  3. A laboratory 8 keV transmission full-field x-ray microscope with a polycapillary as condenser for bright and dark field imaging

    SciTech Connect

    Baumbach, S. Wilhein, T.; Kanngießer, B.; Malzer, W.; Stiel, H.

    2015-08-15

    This article introduces a laboratory setup of a transmission full-field x-ray microscope at 8 keV photon energy. The microscope operates in bright and dark field imaging mode with a maximum field of view of 50 μm. Since the illumination geometry determines whether the sample is illuminated homogeneously and moreover, if different imaging methods can be applied, the condenser optic is one of the most significant parts. With a new type of x-ray condenser, a polycapillary optic, we realized bright field imaging and for the first time dark field imaging at 8 keV photon energy in a laboratory setup. A detector limited spatial resolution of 210 nm is measured on x-ray images of Siemens star test patterns.

  4. A laboratory 8 keV transmission full-field x-ray microscope with a polycapillary as condenser for bright and dark field imaging

    NASA Astrophysics Data System (ADS)

    Baumbach, S.; Kanngießer, B.; Malzer, W.; Stiel, H.; Wilhein, T.

    2015-08-01

    This article introduces a laboratory setup of a transmission full-field x-ray microscope at 8 keV photon energy. The microscope operates in bright and dark field imaging mode with a maximum field of view of 50 μm. Since the illumination geometry determines whether the sample is illuminated homogeneously and moreover, if different imaging methods can be applied, the condenser optic is one of the most significant parts. With a new type of x-ray condenser, a polycapillary optic, we realized bright field imaging and for the first time dark field imaging at 8 keV photon energy in a laboratory setup. A detector limited spatial resolution of 210 nm is measured on x-ray images of Siemens star test patterns.

  5. Grain size determination in nano-scale polycrystalline aggregates by precession illumination-hollow cone dark field imaging in the transmission electron microscope

    SciTech Connect

    Kulovits, A.K. Facco, G.; Wiezorek, J.M.K.

    2012-01-15

    Precession illumination hollow cone dark field (PI-HCDF) transmission electron microscopy (TEM) provides high contrast multi-beam dark field images, which are suitable for effective and robust grain size measurements in nano-scale polycrystalline aggregates. Precession illumination with slightly converged electron beam probes and precession angles up to 3 Degree-Sign has been produced using a computer-controlled system using a JEOL JEM 2000FX TEM instrument. Theoretical and practical aspects of the experimental technique are discussed using example precession illumination hollow cone diffraction patterns from single crystalline NiAl and the importance of selecting the appropriate precession angle for PI-HCDF image formation and interpretation is described. Results obtained for precession illumination are compared with those of conventional parallel beam illumination experiments. Nanocrystalline Al has been used to evaluate the influence of the precession angle on PI-HCDF image contrast with a focus on grain size analysis. PI-HCDF imaging has been applied for grain size measurements in regions of a nanocrystalline Al thin film adjacent to the edge of a pulsed laser melted and rapidly solidified region and determined the dimensions of a heat-affected zone. - Highlights: Black-Right-Pointing-Pointer New TEM method for grain size measurements combines TEM resolution with obtainability of statistically significant data sets. Black-Right-Pointing-Pointer We use precession illumination to produce time precession illumination hollow cone diffraction patterns PI-HCDP. Black-Right-Pointing-Pointer Contrast in dark field images (PI-HCDF) formed from PI-HCDP is easy to interpret as dynamical effects are reduced. Black-Right-Pointing-Pointer PI-HCDFs use several time-averaged g-rings simultaneously and contain more information than conventional DF-images. Black-Right-Pointing-Pointer Easy contrast interpretation and less dark field images required, allows fast, robust and

  6. The influence of laser scribing on magnetic domain formation in grain oriented electrical steel visualized by directional neutron dark-field imaging.

    PubMed

    Rauscher, P; Betz, B; Hauptmann, J; Wetzig, A; Beyer, E; Grünzweig, C

    2016-12-02

    The performance and degree of efficiency of transformers are directly determined by the bulk magnetic properties of grain oriented electrical steel laminations. The core losses can be improved by post manufacturing methods, so-called domain refinement techniques. All these methods induce mechanical or thermal stress that refines the domain structure. The most commonly used technique is laser scribing due to the no-contact nature and the ease of integration in existing production systems. Here we show how directional neutron dark-field imaging allows visualizing the impact of laser scribing on the bulk and supplementary domain structure. In particular, we investigate the domain formation during magnetization of samples depending on laser treatment parameters such as laser energy and line distances. The directional dark-field imaging findings were quantitatively interpreted in the context with global magnetic hysteresis measurements. Especially we exploit the orientation sensitivity in the dark-field images to distinguish between different domain structures alignment and their relation to the laser scribing process.

  7. The influence of laser scribing on magnetic domain formation in grain oriented electrical steel visualized by directional neutron dark-field imaging

    NASA Astrophysics Data System (ADS)

    Rauscher, P.; Betz, B.; Hauptmann, J.; Wetzig, A.; Beyer, E.; Grünzweig, C.

    2016-12-01

    The performance and degree of efficiency of transformers are directly determined by the bulk magnetic properties of grain oriented electrical steel laminations. The core losses can be improved by post manufacturing methods, so-called domain refinement techniques. All these methods induce mechanical or thermal stress that refines the domain structure. The most commonly used technique is laser scribing due to the no-contact nature and the ease of integration in existing production systems. Here we show how directional neutron dark-field imaging allows visualizing the impact of laser scribing on the bulk and supplementary domain structure. In particular, we investigate the domain formation during magnetization of samples depending on laser treatment parameters such as laser energy and line distances. The directional dark-field imaging findings were quantitatively interpreted in the context with global magnetic hysteresis measurements. Especially we exploit the orientation sensitivity in the dark-field images to distinguish between different domain structures alignment and their relation to the laser scribing process.

  8. The influence of laser scribing on magnetic domain formation in grain oriented electrical steel visualized by directional neutron dark-field imaging

    PubMed Central

    Rauscher, P.; Betz, B.; Hauptmann, J.; Wetzig, A.; Beyer, E.; Grünzweig, C.

    2016-01-01

    The performance and degree of efficiency of transformers are directly determined by the bulk magnetic properties of grain oriented electrical steel laminations. The core losses can be improved by post manufacturing methods, so-called domain refinement techniques. All these methods induce mechanical or thermal stress that refines the domain structure. The most commonly used technique is laser scribing due to the no-contact nature and the ease of integration in existing production systems. Here we show how directional neutron dark-field imaging allows visualizing the impact of laser scribing on the bulk and supplementary domain structure. In particular, we investigate the domain formation during magnetization of samples depending on laser treatment parameters such as laser energy and line distances. The directional dark-field imaging findings were quantitatively interpreted in the context with global magnetic hysteresis measurements. Especially we exploit the orientation sensitivity in the dark-field images to distinguish between different domain structures alignment and their relation to the laser scribing process. PMID:27910922

  9. Imaging performance of annular apertures. II - Line spread functions

    NASA Technical Reports Server (NTRS)

    Tschunko, H. F. A.

    1978-01-01

    Line images formed by aberration-free optical systems with annular apertures are investigated in the whole range of central obstruction ratios. Annular apertures form lines images with central and side line groups. The number of lines in each line group is given by the ratio of the outer diameter of the annular aperture divided by the width of the annulus. The theoretical energy fraction of 0.889 in the central line of the image formed by an unobstructed aperture increases for centrally obstructed apertures to 0.932 for the central line group. Energy fractions for the central and side line groups are practically constant for all obstruction ratios and for each line group. The illumination of rectangular secondary apertures of various length/width ratios by apertures of various obstruction ratios is discussed.

  10. Dark-field competition

    NASA Astrophysics Data System (ADS)

    Baumbach, Christoph; mcissbc

    2014-04-01

    In reply to the physicsworld.com news story “Dark field illuminates X-ray imaging” (25 February, http://ow.ly/ulJnl), which concerns new research by Robert Cernik and colleagues (Proc. R. Soc. A 10.1098/rspa.2013.0629).

  11. Piezoelectric annular array for large depth of field photoacoustic imaging

    PubMed Central

    Passler, K.; Nuster, R.; Gratt, S.; Burgholzer, P.; Paltauf, G.

    2011-01-01

    A piezoelectric detection system consisting of an annular array is investigated for large depth of field photoacoustic imaging. In comparison to a single ring detection system, X-shaped imaging artifacts are suppressed. Sensitivity and image resolution studies are performed in simulations and in experiments and compared to a simulated spherical detector. In experiment an eight ring detection systems offers an extended depth of field over a range of 16 mm with almost constant lateral resolution. PMID:21991555

  12. Simulation framework for coherent and incoherent X-ray imaging and its application in Talbot-Lau dark-field imaging.

    PubMed

    Ritter, André; Bartl, Peter; Bayer, Florian; Gödel, Karl C; Haas, Wilhelm; Michel, Thilo; Pelzer, Georg; Rieger, Jens; Weber, Thomas; Zang, Andrea; Anton, Gisela

    2014-09-22

    A simulation framework for coherent X-ray imaging, based on scalar diffraction theory, is presented. It contains a core C++ library and an additional Python interface. A workflow is presented to include contributions of inelastic scattering obtained with Monte-Carlo methods. X-ray Talbot-Lau interferometry is the primary focus of the framework. Simulations are in agreement with measurements obtained with such an interferometer. Especially, the dark-field signal of densely packed PMMA microspheres is predicted. A realistic modeling of the microsphere distribution, which is necessary for correct results, is presented. The framework can be used for both setup design and optimization but also to test and improve reconstruction methods.

  13. Linearization of an annular image by using a diffractive optic

    NASA Technical Reports Server (NTRS)

    Matthys, Donald R.

    1996-01-01

    The goal for this project is to develop the algorithms for fracturing the zones defined by the mapping transformation, and to actually produce the binary optic in an appropriate setup. In 1984 a side-viewing panoramic viewing system was patented, consisting of a single piece of glass with spherical surfaces which produces a 360 degree view of the region surrounding the lens which extends about 25 degrees in front of and 20 degrees behind the lens. The system not only produces images of good quality, it is also afocal, i.e., images stay in focus for objects located right next to the lens as well as those located far from the lens. The lens produced a panoramic view in an annular shaped image, and so the lens was called a PAL (panoramic annular lens). When applying traditional measurements to PAL images, it is found advantageous to linearize the annular image. This can easily be done with a computer and such a linearized image can be produced within about 40 seconds on current microcomputers. However, this process requires a frame-grabber and a computer, and is not real-time. Therefore, it was decided to try to perform this linearization optically by using a diffractive optic.

  14. Dark-field X-ray ptychography: Towards high-resolution imaging of thick and unstained biological specimens

    NASA Astrophysics Data System (ADS)

    Suzuki, Akihiro; Shimomura, Kei; Hirose, Makoto; Burdet, Nicolas; Takahashi, Yukio

    2016-10-01

    The phase shift of light or electrons in objects is now necessary for probing weak-phase objects such as unstained biological specimens. Optical microscopy (OM) and transmission electron microscopy (TEM) have been used to observe weak-phase objects. However, conventional OM has low spatial resolution and TEM is limited to thin specimens. Here, we report on the development of dark-field X-ray ptychography, which combines X-ray ptychography and X-ray in-line holography, to observe weak-phase objects with a phase resolution better than 0.01 rad, a spatial resolution better than 15 nm, and a field of view larger than 5 μm. We apply this method to the observation of both the outline and magnetosomes of the magnetotactic bacteria MO-1. Observation of thick samples with high resolution is expected to find broad applications in not only biology but also materials science.

  15. Dark-field X-ray ptychography: Towards high-resolution imaging of thick and unstained biological specimens

    PubMed Central

    Suzuki, Akihiro; Shimomura, Kei; Hirose, Makoto; Burdet, Nicolas; Takahashi, Yukio

    2016-01-01

    The phase shift of light or electrons in objects is now necessary for probing weak-phase objects such as unstained biological specimens. Optical microscopy (OM) and transmission electron microscopy (TEM) have been used to observe weak-phase objects. However, conventional OM has low spatial resolution and TEM is limited to thin specimens. Here, we report on the development of dark-field X-ray ptychography, which combines X-ray ptychography and X-ray in-line holography, to observe weak-phase objects with a phase resolution better than 0.01 rad, a spatial resolution better than 15 nm, and a field of view larger than 5 μm. We apply this method to the observation of both the outline and magnetosomes of the magnetotactic bacteria MO-1. Observation of thick samples with high resolution is expected to find broad applications in not only biology but also materials science. PMID:27734961

  16. Direct imaging of hydrogen-atom columns in a crystal by annular bright-field electron microscopy.

    PubMed

    Ishikawa, Ryo; Okunishi, Eiji; Sawada, Hidetaka; Kondo, Yukihito; Hosokawa, Fumio; Abe, Eiji

    2011-04-01

    Enhancing the imaging power of microscopy to identify all chemical types of atom, from low- to high-atomic-number elements,would significantly contribute for a direct determination of material structures. Electron microscopes have successfully provided images of heavy-atom positions, particularly by the annular dark-field method, but detection of light atoms was difficult owing to their weak scattering power. Recent developments of aberration-correction electron optics have significantly advanced the microscope performance, enabling identification of individual light atoms such as oxygen, nitrogen, carbon, boron and lithium. However, the lightest hydrogen atom has not yet been observed directly, except in the specific condition of hydrogen adatoms on a graphene membrane. Here we show the first direct imaging of the hydrogen atom in a crystalline solid YH(2), based on a classic 'hollow-cone' illumination theory combined with state-of-the-art scanning transmission electronmicroscopy. The optimized hollow-cone condition derived from the aberration-corrected microscope parameters confirms that the information transfer can be extended to 22.5 nm(-1), which corresponds to a spatial resolution of about 44.4 pm. These experimental conditions can be readily realized with the annular bright-field imaging in scanning transmission electron microscopy according to reciprocity, revealing successfully the hydrogen-atom columns as dark dots, as anticipated from phase contrast of a weak-phase object.

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

    PubMed

    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.

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

    PubMed

    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.

  19. Dark-field imaging based on post-processed electron backscatter diffraction patterns of bulk crystalline materials in a scanning electron microscope.

    PubMed

    Brodusch, Nicolas; Demers, Hendrix; Gauvin, Raynald

    2015-01-01

    Dark-field (DF) images were acquired in the scanning electron microscope with an offline procedure based on electron backscatter diffraction (EBSD) patterns (EBSPs). These EBSD-DF images were generated by selecting a particular reflection on the electron backscatter diffraction pattern and by reporting the intensity of one or several pixels around this point at each pixel of the EBSD-DF image. Unlike previous studies, the diffraction information of the sample is the basis of the final image contrast with a pixel scale resolution at the EBSP providing DF imaging in the scanning electron microscope. The offline facility of this technique permits the selection of any diffraction condition available in the diffraction pattern and displaying the corresponding image. The high number of diffraction-based images available allows a better monitoring of deformation structures compared to electron channeling contrast imaging (ECCI) which is generally limited to a few images of the same area. This technique was applied to steel and iron specimens and showed its high capability in describing more rigorously the deformation structures around micro-hardness indents. Due to the offline relation between the reference EBSP and the EBSD-DF images, this new technique will undoubtedly greatly improve our knowledge of deformation mechanism and help to improve our understanding of the ECCI contrast mechanisms.

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

    NASA Astrophysics Data System (ADS)

    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.

  1. Visualization of lithium ions by annular bright field imaging.

    PubMed

    Oshima, Yoshifumi; Lee, Soyeon; Takayanagi, Kunio

    2016-10-14

    The detection of lithium ions is required for characterization of lithium ion batteries, since the movement of lithium ions in the battery is one of the key ways to improve the performance. Annular bright field (ABF) imaging enables us to visualize individual lithium atomic columns simultaneously with heavy elements. Furthermore, it has been found that the number of lithium ions at the column is countable when the specimen is thin. These results suggest that movement of lithium ions in the material can be observed by taking consecutive ABF images during operation or in situ ABF observation. Actually, the spinel structure of L2V4O crystals was directly observed to be transformed into the defective NaCl structure at the moment when lithium ions were extracted from the original position during electron beam irradiation. We clarify the features of ABF imaging by comparing it with HAADF imaging in order to understand what information can be obtained by ABF imaging directly.

  2. An inexpensive approach for bright-field and dark-field imaging by scanning transmission electron microscopy in scanning electron microscopy.

    PubMed

    Patel, Binay; Watanabe, Masashi

    2014-02-01

    Scanning transmission electron microscopy in scanning electron microscopy (STEM-in-SEM) is a convenient technique for soft materials characterization. Various specimen-holder geometries and detector arrangements have been used for bright-field (BF) STEM-in-SEM imaging. In this study, to further the characterization potential of STEM-IN-SEM, a new specimen holder has been developed to facilitate direct detection of BF signals and indirect detection of dark-field (DF) signals without the need for substantial instrument modification. DF imaging is conducted with the use of a gold (Au)-coated copper (Cu) plate attached to the specimen holder which directs highly scattered transmitted electrons to an off-axis yttrium-aluminum-garnet (YAG) detector. A hole in the copper plate allows for BF imaging with a transmission electron (TE) detector. The inclusion of an Au-coated Cu plate enhanced DF signal intensity. Experiments validating the acquisition of true DF signals revealed that atomic number (Z) contrast may be achieved for materials with large lattice spacing. However, materials with small lattice spacing still exhibit diffraction contrast effects in this approach. The calculated theoretical fine probe size is 1.8 nm. At 30 kV, in this indirect approach, DF spatial resolution is limited to 3.2 nm as confirmed experimentally.

  3. On the visibility of "heavy" atoms in dark-field STEM

    NASA Astrophysics Data System (ADS)

    Shannon, M. D.; Nellist, P. D.; Nicolosi, V.; Shannon, G. B.; Shmeliov, A.

    2012-07-01

    One of the most useful and apparently straightforward attributes of annular dark-field (ADF) STEM imaging is the ability to image heavy atoms on relatively light substrates using Z-contrast (High-Angle ADF) imaging. From multislice calculations, however, some isolated heavy atoms, e.g. Re, can go undetected in a thin Co matrix in standard aberration-corrected HAADF-STEM imaging of catalyst nanoparticles oriented accurately on a zone-axis [2]. More recently simultaneous Medium-Angle and High-Angle ADF imaging of a few layers of BN has shown experimentally that some adatoms are invisible in MAADF whilst exhibiting very strong contrast in HAADF. Simulations confirm that this can occur for atoms such as sodium. In both situations HOLZ ring imaging can be used to extract additional information.

  4. Three dimensional design of silver nanoparticle assemblies embedded in dielectrics for Raman spectroscopy enhancement and dark-field imaging.

    PubMed

    Carles, Robert; Farcau, Cosmin; Bonafos, Caroline; Benassayag, Gérard; Bayle, Maxime; Benzo, Patrizio; Groenen, Jesse; Zwick, Antoine

    2011-11-22

    A strategy to design and fabricate hybrid metallic-dielectric substrates for optical spectroscopy and imaging is proposed. Different architectures consisting of three-dimensional patterns of metallic nanoparticles embedded in dielectric layers are conceived to simultaneously exploit the optical interference phenomenon in stratified media and localized surface plasmon resonances on metal nanoparticles. These structures are based on a simultaneous control of opto-electronic properties at three scales (3S) (~2/20/200 nm) and along three directions (3D). By ultralow energy ion implantation through a microfabricated stencil we precisely control the size, density, and location of silver nanoparticles embedded in silica/silicon thin films. Elastic (Rayleigh) and inelastic (Raman) scattering imaging assisted by simulations were used to analyze the optical response of these "3S-3D" patterned layers. The reflectance contrast is strongly enhanced when resonance conditions between the stationary electromagnetic field in the dielectric matrix and the localized plasmon resonance in the silver nanoparticles are realized. The potential of these 3S-3D metal-dielectric structures as surface-enhanced Raman scattering substrates is demonstrated. These novel kinds of plasmonic-photonic architectures are reproducible and stable; they preserve flat and chemically uniform surfaces, offering opportunities for the development of efficient and reusable substrates for optical spectroscopy and imaging enhancement.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Dark-field illuminated reflectance fiber bundle endoscopic microscope

    NASA Astrophysics Data System (ADS)

    Liu, Xuan; Huang, Yong; Kang, Jin U.

    2011-04-01

    We propose a reflectance fiber bundle microscope using a dark-field illumination configuration for applications in endoscopic medical imaging and diagnostics. Our experiment results show that dark-field illumination can effectively suppress strong specular reflection from the proximal end of the fiber bundle. We realized a lateral resolution of 4.4 μm using the dark-field illuminated fiber bundle configuration. To demonstrate the feasibility of using the system to study cell morphology, we obtained still and video images of two thyroid cancer cell lines. Our results clearly allow differentiation of different cancer cell types.

  7. Dark Field Microscopy for Analytical Laboratory Courses

    SciTech Connect

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

    2014-06-10

    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 observe and measure individual crystal growth during a replacement reaction between copper and silver nitrate. The experiment allows for quantitative, qualitative, and image data analyses for undergraduate students.

  8. On the visibility of very thin specimens in annular bright field scanning transmission electron microscopy

    SciTech Connect

    Phillips, P. J.; Klie, R. F.

    2013-07-15

    Annular bright field (ABF) scanning transmission electron microscopy (STEM) is emerging as an important observation mode for its ability to simultaneously image both heavy and light elements. However, recent results have demonstrated that in the limit of a very thin specimen (a few atomic layers), the ABF and high angle annular dark field (HAADF) signals cease to be intuitively related: a phenomenon which is generally irrelevant when imaging 'normal' specimens. ABF/HAADF STEM observations and multislice image simulations of two catalyst samples of differing atomic weights are presented; it is shown that the nature of the ABF signal is specimen dependent.

  9. An in situ probe for on-line monitoring of cell density and viability on the basis of dark field microscopy in conjunction with image processing and supervised machine learning.

    PubMed

    Wei, Ning; You, Jia; Friehs, Karl; Flaschel, Erwin; Nattkemper, Tim Wilhelm

    2007-08-15

    Fermentation industries would benefit from on-line monitoring of important parameters describing cell growth such as cell density and viability during fermentation processes. For this purpose, an in situ probe has been developed, which utilizes a dark field illumination unit to obtain high contrast images with an integrated CCD camera. To test the probe, brewer's yeast Saccharomyces cerevisiae is chosen as the target microorganism. Images of the yeast cells in the bioreactors are captured, processed, and analyzed automatically by means of mechatronics, image processing, and machine learning. Two support vector machine based classifiers are used for separating cells from background, and for distinguishing live from dead cells afterwards. The evaluation of the in situ experiments showed strong correlation between results obtained by the probe and those by widely accepted standard methods. Thus, the in situ probe has been proved to be a feasible device for on-line monitoring of both cell density and viability with high accuracy and stability.

  10. Stroke volume and mitral annular velocities. Insights from tissue Doppler imaging.

    PubMed

    Bruch, C; Stypmann, J; Gradaus, R; Breithardt, G; Wichter, T

    2004-10-01

    The aim of this study was to assess the impact of stroke volume (SV) on mitral annular velocities derived from tissue Doppler imaging (TDI). To this end, conventional echocardiographic variables and TDI derived mitral annular velocities (S', E', A') were obtained in 14 patients (pts) with increased SV (due to primary mitral (n=12) (ISV group)), in 41 pts with reduced SV (due to ischemic (n=27) or dilated cardiomyopathy (n=9) or hypertensive heart disease (n=5) (RSV group)) and 29 asymptomatic controls with normal SV (CON group). Systolic (S') and early diastolic (E') mitral annular velocities were elevated in the ISV group in the comparison to the CON group, but were significantly reduced in the RSV group. Late diastolic annular velocities (A') did not differ between the ISV and the CON group, but were lowest in the RSV group. On simple linear regression analysis, SV was significantly related to S' (r=0.74, p<0.001), to E' (r=0.74, p<0.001) and to A' (r=0.43, p<0.01). On multiple regression analysis, SV was a stronger independent predictor of S' and E' than conventional systolic or diastolic echocardiographic variables. Thus, stroke volume has a significant impact on TDI derived systolic (S') and early diastolic (E') mitral annular velocities. This should be considered, when TDI is used in the evaluation of LV performance or in the estimation of filling pressures.

  11. Analyzing Microchips With Dark-Field Negative Photomicrography

    NASA Technical Reports Server (NTRS)

    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.

  12. Selective color imaging using weighted interleaved multiple annular linear diffractive axicons.

    PubMed

    Bialic, Emilie; Petiton, Valéry; de Bougrenet de la Tocnaye, Jean-Louis

    2012-07-10

    Annular linear diffractive axicons are optical devices providing chromatic imaging over an extended depth of focus when illuminated by a white light. To improve their low radiometric performance, multiple annular linear diffractive axicons (MALDAs) have been introduced. Their chromatic properties are well known and constrained by dispersion laws. A first attempt to freely combine colors or wavelength bands has been obtained with interleaved MALDAs (I_MALDAs). However, such optics do not provide a full decoupling between wavelength combination and brightness control required in the CIE color space to address any colors. We present here a new category of I_MALDA providing this capability when illuminated by a white source containing tristimulus (red/green/blue) values. We assess both theoretically and experimentally imaging qualities of such optics with respect to two different interleaving techniques and suggest some potential applications, in particular in the field of anticounterfeit and authentication techniques.

  13. A Flexible Annular-Array Imaging Platform for Micro-Ultrasound

    PubMed Central

    Qiu, Weibao; Yu, Yanyan; Chabok, Hamid Reza; Liu, Cheng; Tsang, Fu Keung; Zhou, Qifa; Shung, K. Kirk; Zheng, Hairong; Sun, Lei

    2013-01-01

    Micro-ultrasound is an invaluable imaging tool for many clinical and preclinical applications requiring high resolution (approximately several tens of micrometers). Imaging systems for micro-ultrasound, including single-element imaging systems and linear-array imaging systems, have been developed extensively in recent years. Single-element systems are cheaper, but linear-array systems give much better image quality at a higher expense. Annular-array-based systems provide a third alternative, striking a balance between image quality and expense. This paper presents the development of a novel programmable and real-time annular-array imaging platform for micro-ultrasound. It supports multi-channel dynamic beamforming techniques for large-depth-of-field imaging. The major image processing algorithms were achieved by a novel field-programmable gate array technology for high speed and flexibility. Real-time imaging was achieved by fast processing algorithms and high-speed data transfer interface. The platform utilizes a printed circuit board scheme incorporating state-of-the-art electronics for compactness and cost effectiveness. Extensive tests including hardware, algorithms, wire phantom, and tissue mimicking phantom measurements were conducted to demonstrate good performance of the platform. The calculated contrast-to-noise ratio (CNR) of the tissue phantom measurements were higher than 1.2 in the range of 3.8 to 8.7 mm imaging depth. The platform supported more than 25 images per second for real-time image acquisition. The depth-of-field had about 2.5-fold improvement compared to single-element transducer imaging. PMID:23287923

  14. A flexible annular-array imaging platform for micro-ultrasound.

    PubMed

    Qiu, Weibao; Yu, Yanyan; Chabok, Hamid Reza; Liu, Cheng; Tsang, Fu Keung; Zhou, Qifa; Shung, K Kirk; Zheng, Hairong; Sun, Lei

    2013-01-01

    Micro-ultrasound is an invaluable imaging tool for many clinical and preclinical applications requiring high resolution (approximately several tens of micrometers). Imaging systems for micro-ultrasound, including single-element imaging systems and linear-array imaging systems, have been developed extensively in recent years. Single-element systems are cheaper, but linear-array systems give much better image quality at a higher expense. Annular-array-based systems provide a third alternative, striking a balance between image quality and expense. This paper presents the development of a novel programmable and real-time annular-array imaging platform for micro-ultrasound. It supports multi-channel dynamic beamforming techniques for large-depth-of-field imaging. The major image processing algorithms were achieved by a novel field-programmable gate array technology for high speed and flexibility. Real-time imaging was achieved by fast processing algorithms and high-speed data transfer interface. The platform utilizes a printed circuit board scheme incorporating state-of-the-art electronics for compactness and cost effectiveness. Extensive tests including hardware, algorithms, wire phantom, and tissue mimicking phantom measurements were conducted to demonstrate good performance of the platform. The calculated contrast-to-noise ratio (CNR) of the tissue phantom measurements were higher than 1.2 in the range of 3.8 to 8.7 mm imaging depth. The platform supported more than 25 images per second for real-time image acquisition. The depth-of-field had about 2.5-fold improvement compared to single-element transducer imaging.

  15. Dual Frequency Band Annular Probe for Volumetric Pulse-echo Optoacoustic Imaging

    NASA Astrophysics Data System (ADS)

    Kalkhoran, Mohammad Azizian; Varray, François; Vray, Didier

    Optoacoustic (OA) pulse echo (PE) imaging is a hybridized modality that is capable of providing physiological information on the basis of anatomical structure. In this work, we propose a dual frequency band annular probe for backward mode volumetric PE/OA imaging. The performance of this design is evaluated based on the spatio-temporal impulse response, three dimensional steerability of the transducer and point spread function. Optimum settings for number of elements in each ring and maximum steering are suggested. The transducer design and synthetic array beamforming simulation are presented. The resolution performance and reconstruction capabilities are shown with the in-silico measurements.

  16. X-ray dark-field radiography facilitates the diagnosis of pulmonary fibrosis in a mouse model.

    PubMed

    Hellbach, Katharina; Yaroshenko, Andre; Willer, Konstantin; Conlon, Thomas M; Braunagel, Margarita B; Auweter, Sigrid; Yildirim, Ali Ö; Eickelberg, Oliver; Pfeiffer, Franz; Reiser, Maximilian F; Meinel, Felix G

    2017-03-23

    The aim of this study was to evaluate whether diagnosing pulmonary fibrosis with projection radiography can be improved by using X-ray dark-field radiograms. Pulmonary X-ray transmission and dark-field images of C57Bl/6N mice, either treated with bleomycin to induce pulmonary fibrosis or PBS to serve as controls, were acquired with a prototype grating-based small-animal scanner. Two blinded readers, both experienced radiologists and familiar with dark-field imaging, had to assess dark-field and transmission images for the absence or presence of fibrosis. Furthermore readers were asked to grade their stage of diagnostic confidence. Histological evaluation of the lungs served as the standard of reference in this study. Both readers showed a notably higher diagnostic confidence when analyzing the dark-field radiographs (p < 0.001). Diagnostic accuracy improved significantly when evaluating the lungs in dark-field images alone (p = 0.02) or in combination with transmission images (p = 0.01) compared to sole analysis of absorption images. Interreader agreement improved from good when assessing only transmission images to excellent when analyzing dark-field images alone or in combination with transmission images. Adding dark-field images to conventional transmission images in a murine model of pulmonary fibrosis leads to an improved diagnosis of this disease on chest radiographs.

  17. Observing the setting and hardening of cementitious materials by X-ray dark-field radiography

    SciTech Connect

    Prade, F.; Chabior, M.; Malm, F.; Grosse, C.U.; Pfeiffer, F.

    2015-08-15

    Novel X-ray imaging methods expand conventional attenuation-based X-ray radiography by the phase- and the dark-field contrasts. While weakly absorbing structures in the specimen can be better visualized in phase contrast, the dark-field contrast provides information about morphological sub-pixel microstructures. Here we report an application of dark-field X-ray radiography for imaging the time-resolved setting process in fresh cement. Our results demonstrate that the microstructural changes within the cement result in a decreasing dark-field signal. We quantify this imaging signal with a time-dependent dark-field scatter coefficient and show its good correlation with the compressional wave velocity. We further present images based on a pixel-wise analysis of the scattering signal and a corresponding logistic fit. These images emphasize the benefit of dark-field imaging of cementitious materials as it provides two dimensional spatial information on the processes within the sample while other established testing techniques only provide information on the bulk average.

  18. Three-dimensional particle imaging by defocusing method with an annular aperture.

    PubMed

    Lin, Dejiao; Angarita-Jaimes, Natalia C; Chen, Siyu; Greenaway, Alan H; Towers, Catherine E; Towers, David P

    2008-05-01

    We propose an annular-aperture-based defocusing technique for three-dimensional (3D) particle metrology from a single camera view. This simple configuration has high optical efficiency and the ability to deal with overlapped defocused images. Initial results show that an uncertainty in depth of 23 microm can be achieved over a range of 10 mm for macroscopic systems. This method can also be applied in microscopy for the measurement of fluorescently doped microparticles, thus providing a promising solution for 3D flow metrology at both macroscales and microscales.

  19. Dark Field Microscopy for Analytical Laboratory Courses

    ERIC Educational Resources Information Center

    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…

  20. Dark-field circular depolarization optical coherence microscopy

    PubMed Central

    Mehta, Kalpesh; Zhang, Pengfei; Yeo, Eugenia Li Ling; Kah, James Chen Yong; Chen, Nanguang

    2013-01-01

    Optical coherence microscopy (OCM) is a widely used structural imaging modality. To extend its application in molecular imaging, gold nanorods are widely used as contrast agents for OCM. However, they very often offer limited sensitivity as a result of poor signal to background ratio. Here we experimentally demonstrate that a novel OCM implementation based on dark-field circular depolarization detection can efficiently detect circularly depolarized signal from gold nanorods and at the same time efficiently suppress the background signals. This results into a significant improvement in signal to background ratio. PMID:24049689

  1. Characterization of the Annular Core Research Reactor (ACRR) Neutron Radiography System Imaging Plane

    NASA Astrophysics Data System (ADS)

    Kaiser, Krista; Chantel Nowlen, K.; DePriest, K. Russell

    2016-02-01

    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 characterized at the imaging plane for the ACRR's neutron radiography system for the 65:1, 125:1 and 250:1 apertures.

  2. High-frequency chirp ultrasound imaging with an annular array for ophthalmologic and small-animal imaging.

    PubMed

    Mamou, Jonathan; Aristizábal, Orlando; Silverman, Ronald H; Ketterling, Jeffrey A; Turnbull, Daniel H

    2009-07-01

    High-frequency ultrasound (HFU, >20 MHz) is an attractive means of obtaining fine-resolution images of biological tissues for ophthalmologic, dermatological and small-animal imaging applications. Even with current improvements in circuit designs and high-frequency equipment, HFU has two inherent limitations. First, HFU images have a limited depth-of-field (DOF) because of the short wavelength and the low fixed F-number of conventional HFU transducers. Second, HFU is usually limited to shallow imaging because of the significant attenuation in most tissues. In a previous study, a five-element annular array with a 17-MHz center frequency was excited using chirp-coded signals, and a synthetic-focusing algorithm was used to extend the DOF and increase penetration depth. In the present study, a similar approach with two different five-element annular arrays operating near a center frequency of 35 MHz is implemented and validated. Following validation studies, the chirp-imaging methods were applied to imaging vitreous-hemorrhage-mimicking phantoms and mouse embryos. Images of the vitreous phantom showed increased sensitivity using the chirp method compared with a standard monocycle imaging method, and blood droplets could be visualized 4mm deeper into the phantom. Three-dimensional datasets of 12.5-day-old mouse embryo heads were acquired in utero using chirp and conventional excitations. Images were formed and brain ventricles were segmented and reconstructed in three dimensions. The brain ventricle volumes for the monocycle excitation exhibited artifacts that were not apparent on the chirp-based dataset reconstruction.

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

    NASA Astrophysics Data System (ADS)

    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.

  4. High-frequency annular array with coaxial illumination for dual-modality ultrasonic and photoacoustic imaging

    NASA Astrophysics Data System (ADS)

    Filoux, Erwan; Sampathkumar, Ashwin; Chitnis, Parag V.; Aristizábal, Orlando; Ketterling, Jeffrey A.

    2013-05-01

    This paper presents a combined ultrasound and photoacoustic (PA) imaging (PAI) system used to obtain high-quality, co-registered images of mouse-embryo anatomy and vasculature. High-frequency ultrasound (HFU, >20 MHz) is utilized to obtain high-resolution anatomical images of small animals while PAI provides high-contrast images of the vascular network. The imaging system is based on a 40 MHz, 5-element, 6 mm aperture annular-array transducer with a 800 μm diameter hole through its central element. The transducer was integrated in a cage-plate assembly allowing for a collimated laser beam to pass through the hole so that the optical and acoustic beams were collinear. The assembly was mounted on a two-axis, motorized stage to enable the simultaneous acquisition of co-registered HFU and PA volumetric data. Data were collected from all five elements in receive and a synthetic-focusing algorithm was applied in post-processing to beamform the data and increase the spatial resolution and depth-of-field (DOF) of the HFU and PA images. Phantom measurements showed that the system could achieve high-resolution images (down to 90 μm for HFU and 150 μm for PAI) and a large DOF of >8 mm. Volume renderings of a mouse embryo showed that the scanner allowed for visualizing morphologically precise anatomy of the entire embryo along with corresponding co-registered vasculature. Major head vessels, such as the superior sagittal sinus or rostral vein, were clearly identified as well as limb bud vasculature.

  5. Analysis of the imaging performance of panoramic annular lens with conic conformal dome

    NASA Astrophysics Data System (ADS)

    Huang, Xiao; Bai, Jian

    2015-10-01

    Panoramic annular lens (PAL) is a kind of the specific wide angle lenses which is widely applied in panoramic imaging especially in aerospace field. As we known, to improve the aerodynamic performance of the aircraft, conformal dome, which notably reduces the drag of an aircraft, is also functioning as an optical window for the inbuilt optical system. However, there is still no report of the specific analysis of the imaging performance of PAL with conformal dome, which is imperative in its aerospace-related applications. In this paper, we propose an analysis of the imaging performance of a certain PAL with various conic conformal domes. Working in visible wavelength, the PAL in our work observes 360° surroundings with a large field of view (FOV) ranging from 30° ~105° . Meanwhile, various thicknesses, half-vertex angles, materials of the conic dome and the central distances between the dome and PAL are considered. The imaging performances, mainly indicated by modulation transfer function (MTF) as well as RMS radius of the spot diagram, are systematically compared. It is proved that, on the contrary to the general cases, the dome partly contributes to the imaging performance of the inbuilt PAL. In particular, with a conic conformal dome in material of K9 glass with a half-vertex angle of 25° and a thickness of 6mm, the maximum MTF at 100lp/mm could be improved by 6.68% with nearly no degeneration of the minimum MTF, and the RMS radius could be improved by 14.76% to 19.46% in different FOV. It is worth to note that the PAL is adaptive to panoramic aerospace applications with conic or quasi-conic conformal dome and the co-design of both PAL and the dome is very important.

  6. Dark Field Technology - A Practical Approach To Local Alignment

    NASA Astrophysics Data System (ADS)

    Beaulieu, David R.; Hellebrekers, Paul P.

    1987-01-01

    A fully automated direct reticle reference alignment system for use in step and repeat camera systems is described. The technique, first outlined by Janus S. Wilczynski, ("Optical Step and Repeat Camera with Dark Field Alignment", J. Vac. Technol., 16(6), Nov./Dec. 1979), has been implemented on GCA Corporation's DSW Wafer Stepper. Results from various process levels covering the typical CMOS process have shown that better than ±0.2μm alignment accuracy can be obtained with minimal process sensitivity. The technique employs fixed illumination and microscope optics to achieve excellent registration stability and maintenance-free operation. Latent image techniques can be exploited for intra-field, grid and focus characterization.

  7. Galectin-3 Reflects Mitral Annular Plane Systolic Excursion Being Assessed by Cardiovascular Magnetic Resonance Imaging

    PubMed Central

    Kim, Seung-Hyun; Natale, Michele; Hoffmann, Julia; Reckord, Nadine; Hoffmann, Ursula; Budjan, Johannes; Henzler, Thomas; Papavassiliu, Theano; Borggrefe, Martin; Bertsch, Thomas; Akin, Ibrahim

    2016-01-01

    Background. This study investigates whether serum levels of galectin-3 may reflect impaired mitral annular plane systolic excursion (MAPSE) in patients undergoing cardiac magnetic resonance imaging (cMRI). Methods. Patients undergoing cMRI during routine clinical care were included prospectively within an all-comers design. Blood samples for biomarker measurements were collected within 24 hours following cMRI. Statistical analyses were performed in all patients and in three subgroups according to MAPSE (MAPSE I: ≥11 mm, MAPSE II: ≥8 mm–<11 mm, and MAPSE III: <8 mm). Patients with right ventricular dysfunction (<50%) were excluded. Results. 84 patients were included in the study. Median LVEF was 59% (IQR 51–64%). Galectin-3 correlated significantly with NT-proBNP (r = 0.42, p = 0.0001). Galectin-3 increased significantly according to the different stages of impaired MAPSE (p = 0.006) and was able to discriminate both patients with impaired MAPSE <11 mm (area under the curve (AUC) = 0.645, p = 0.024) and <8 mm (AUC = 0.733, p = 0.003). Combining galectin-3 with NT-proBNP improved discrimination of MAPSE <8 mm (AUC 0.803, p = 0.0001). In multivariable logistic regression models galectin-3 was still associated with impaired MAPSE (MAPSE < 11 mm: odds ratio (OR) = 3.53, p = 0.018; MAPSE < 8 mm: OR = 3.18, p = 0.06). Conclusions. Galectin-3 reflects MAPSE being assessed by cardiac MRI. PMID:28044067

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

    PubMed

    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

    2013-04-21

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  10. A generalized quantitative interpretation of dark-field contrast for highly concentrated microsphere suspensions

    PubMed Central

    Gkoumas, Spyridon; Villanueva-Perez, Pablo; Wang, Zhentian; Romano, Lucia; Abis, Matteo; Stampanoni, Marco

    2016-01-01

    In X-ray grating interferometry, dark-field contrast arises due to partial extinction of the detected interference fringes. This is also called visibility reduction and is attributed to small-angle scattering from unresolved structures in the imaged object. In recent years, analytical quantitative frameworks of dark-field contrast have been developed for highly diluted monodisperse microsphere suspensions with maximum 6% volume fraction. These frameworks assume that scattering particles are separated by large enough distances, which make any interparticle scattering interference negligible. In this paper, we start from the small-angle scattering intensity equation and, by linking Fourier and real-space, we introduce the structure factor and thus extend the analytical and experimental quantitative interpretation of dark-field contrast, for a range of suspensions with volume fractions reaching 40%. The structure factor accounts for interparticle scattering interference. Without introducing any additional fitting parameters, we successfully predict the experimental values measured at the TOMCAT beamline, Swiss Light Source. Finally, we apply this theoretical framework to an experiment probing a range of system correlation lengths by acquiring dark-field images at different energies. This proposed method has the potential to be applied in single-shot-mode using a polychromatic X-ray tube setup and a single-photon-counting energy-resolving detector. PMID:27734931

  11. Non-invasive differentiation of kidney stone types using X-ray dark-field radiography.

    PubMed

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

    2015-04-15

    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. Depending on their chemical composition, microscopic growth structure and morphology the various types of kidney stones show strongly varying, partially opposite contrasts in absorption and dark-field imaging. By assessing the microscopic calculi morphology with high resolution micro-computed tomography measurements, we illustrate the dependence of dark-field signal strength on the respective stone type. Finally, we utilize X-ray dark-field radiography as a non-invasive, highly sensitive (100%) and specific (97%) tool for the differentiation of calcium oxalate, uric acid and mixed types of stones, while additionally improving the detectability of radio-lucent calculi. We prove clinical feasibility of the here proposed method by accurately classifying renal stones, embedded within a fresh pig kidney, using dose-compatible measurements and a quick and simple visual inspection.

  12. A generalized quantitative interpretation of dark-field contrast for highly concentrated microsphere suspensions

    NASA Astrophysics Data System (ADS)

    Gkoumas, Spyridon; Villanueva-Perez, Pablo; Wang, Zhentian; Romano, Lucia; Abis, Matteo; Stampanoni, Marco

    2016-10-01

    In X-ray grating interferometry, dark-field contrast arises due to partial extinction of the detected interference fringes. This is also called visibility reduction and is attributed to small-angle scattering from unresolved structures in the imaged object. In recent years, analytical quantitative frameworks of dark-field contrast have been developed for highly diluted monodisperse microsphere suspensions with maximum 6% volume fraction. These frameworks assume that scattering particles are separated by large enough distances, which make any interparticle scattering interference negligible. In this paper, we start from the small-angle scattering intensity equation and, by linking Fourier and real-space, we introduce the structure factor and thus extend the analytical and experimental quantitative interpretation of dark-field contrast, for a range of suspensions with volume fractions reaching 40%. The structure factor accounts for interparticle scattering interference. Without introducing any additional fitting parameters, we successfully predict the experimental values measured at the TOMCAT beamline, Swiss Light Source. Finally, we apply this theoretical framework to an experiment probing a range of system correlation lengths by acquiring dark-field images at different energies. This proposed method has the potential to be applied in single-shot-mode using a polychromatic X-ray tube setup and a single-photon-counting energy-resolving detector.

  13. Imaging performance of annular apertures. IV - Apodization and point spread functions. V - Total and partial energy integral functions

    NASA Technical Reports Server (NTRS)

    Tschunko, H. F. A.

    1983-01-01

    Reference is made to a study by Tschunko (1979) in which it was discussed how apodization modifies the modulation transfer function for various central obstruction ratios. It is shown here how apodization, together with the central obstruction ratio, modifies the point spread function, which is the basic element for the comparison of imaging performance and for the derivation of energy integrals and other functions. At high apodization levels and lower central obstruction (less than 0.1), new extended radial zones are formed in the outer part of the central ring groups. These transmutation of the image functions are of more than theoretical interest, especially if the irradiance levels in the outer ring zones are to be compared to the background irradiance levels. Attention is then given to the energy distribution in point images generated by annular apertures apodized by various transmission functions. The total energy functions are derived; partial energy integrals are determined; and background irradiance functions are discussed.

  14. Correlation of right ventricular ejection fraction and tricuspid annular plane systolic excursion in tetralogy of Fallot by magnetic resonance imaging.

    PubMed

    Morcos, Peter; Vick, G Wesley; Sahn, David J; Jerosch-Herold, Michael; Shurman, Alan; Sheehan, Florence H

    2009-03-01

    The correlation between right ventricular ejection fraction (RVEF) and tricuspid annular plane systolic excursion (TAPSE) by two-dimensional (2-D) echo has been repeatedly validated, but not by magnetic resonance imaging (MRI) nor in patients with congenital heart disease. We tested whether TAPSE measurements by MRI correlate with RVEF in surgically repaired tetralogy of Fallot (TOF) patients. TAPSE was measured from systolic displacement of the RV-freewall/tricuspid annular plane junction in the apical 4-chamber view in 7 normal subjects and 14 TOF patients. The RV was reconstructed in 3-D from manually traced borders on MR images to compute true EF. Because we previously observed discrepancy between TAPSE and RVEF in the presence of regional dysfunction, we also analyzed RV wall motion in terms of regional stroke volume at 20 short axis slices from apex to tricuspid annulus. RVEF was 52 +/- 3% in normal subjects and 41 +/- 9% in TOF (P < 0.01). TAPSE correlated weakly (r = 0.50, P < 0.05) with RVEF. TOF patients exhibited increased regional stroke volume from apical portions of the RV and decreased regional stroke volume at the base compared to normal (P < 0.05 at 15 of 20 slices). Regional stroke volume in apical slices correlated inversely with RVEF such that patients with higher apical stroke volume had lower RVEF (P < 0.05). TAPSE is not a reliable measure of RVEF in TOF by MRI. TAPSE may be of limited use in conditions that exhibit abnormal regional contraction.

  15. Multiple annular linear diffractive axicons.

    PubMed

    Bialic, Emilie; de la Tocnaye, Jean-Louis de Bougrenet

    2011-04-01

    We propose a chromatic analysis of multiple annular linear diffractive axicons. Large aperture axicons are optical devices providing achromatic nondiffracting beams, with an extended depth of focus, when illuminated by a white light source, due to chromatic foci superimposition. Annular apertures introduce chromatic foci separation, and because chromatic aberrations result in focal segment axial shifts, polychromatic imaging properties are partially lost. We investigate here various design parameters that can be used to achieve color splitting, filtering, and combining using these properties. In order to improve the low-power efficiency of a single annular axicon, we suggest a spatial multiplexing of concentric annular axicons with different sizes and periods we call multiple annular aperture diffractive axicons (MALDAs). These are chosen to maintain focal depths while enabling color imaging with sufficient diffraction efficiency. Illustrations are given for binary phase diffractive axicons, considering technical aspects such as grating design wavelength and phase dependence due to the grating thickness.

  16. A design of panoramic lens system to realize the projection from the local annular object field to rectangular image field by using freeform surfaces

    NASA Astrophysics Data System (ADS)

    Bian, Xuqi; Ma, Tao; Zhang, Jun

    2016-10-01

    Nowadays, panoramic annular lens (PAL) applies in aerospace, robotics vision, industrial pipeline endoscope and corporate video conferencing. A cylinder-to-plane projection which called the Flat Cylinder Perspective (FCP) is adopted in PAL. The FCP projected the three-dimensional cylindrical field object onto a two-dimensional annular image plane. The optical system has fade zone in the center of detector. Based on the structure of the PAL system, this paper shows that a panoramic lens is designed with free-form surfaces. In the designed optical system, the local annular object field of view is projected onto a rectangular image plane. The free-form panoramic lens has a wide field of view of 140°in horizontal direction and a field of view of 40°in vertical direction. The design of the panoramic lens can maximize the use of area and have no fade zone in rectangular detector.

  17. Hyperspectral Dark Field Optical Microscopy of Single Silver Nanospheres

    SciTech Connect

    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.

  18. Development of hard X-ray dark-field microscope using full-field optics

    NASA Astrophysics Data System (ADS)

    Takano, Hidekazu; Azuma, Hiroaki; Shimomura, Sho; Tsuji, Takuya; Tsusaka, Yoshiyuki; Kagoshima, Yasushi

    2016-10-01

    We develop a dark-field X-ray microscope using full-field optics based on a synchrotron beamline. Our setup consists of a condenser system and a microscope objective with an angular acceptance larger than that of the condenser. The condenser system is moved downstream from its regular position such that the focus of the condenser is behind the objective. The dark-field microscope optics are configured by excluding the converging beam from the condenser at the focal point. The image properties of the system are evaluated by observing and calculating a Siemens star test chart with 10 keV X-rays. Our setup allows easy switching to bright-field imaging.

  19. Annular wing

    NASA Technical Reports Server (NTRS)

    Walker, H. J. (Inventor)

    1981-01-01

    An annular wing particularly suited for use in supporting in flight an aircraft characterized by the absence of directional stabilizing surfaces is described. The wing comprises a rigid annular body of a substantially uniformly symmetrical configuration characterized by an annular positive lifting surface and cord line coincident with the segment of a line radiating along the surface of an inverted truncated cone. A decalage is established for the leading and trailing semicircular portions of the body, relative to instantaneous line of flight, and a dihedral for the laterally opposed semicircular portions of the body, relative to the line of flight. The direction of flight and climb angle or glide slope angle are established by selectively positioning the center of gravity of the wing ahead of the aerodynamic center along the radius coincident with an axis for a selected line of flight.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27072871

  2. Quantitative laser speckle flowmetry of the in vivo microcirculation using sidestream dark field microscopy

    PubMed Central

    Nadort, Annemarie; Woolthuis, Rutger G.; van Leeuwen, Ton G.; Faber, Dirk J.

    2013-01-01

    We present integrated Laser Speckle Contrast Imaging (LSCI) and Sidestream Dark Field (SDF) flowmetry to provide real-time, non-invasive and quantitative measurements of speckle decorrelation times related to microcirculatory flow. Using a multi exposure acquisition scheme, precise speckle decorrelation times were obtained. Applying SDF-LSCI in vitro and in vivo allows direct comparison between speckle contrast decorrelation and flow velocities, while imaging the phantom and microcirculation architecture. This resulted in a novel analysis approach that distinguishes decorrelation due to flow from other additive decorrelation sources. PMID:24298399

  3. Impact of vessel diameter and bandwidth of illumination in sidestream dark-field oximetry

    PubMed Central

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

    2015-01-01

    We investigate the possibility of oxygen saturation estimation from images obtained by the sidestream dark-field (SDF) technique. The SDF technique is a method for microvascular imaging. In SDF imaging, light enters a tissue directly from illumination sources configured around a camera and then the camera captures the light scattered by the tissue. To advance the capability of the SDF imaging system, we develop a SDF oximetry method with LED illumination sources. In this paper, we evaluate some SDF oximetry methods from virtual SDF images obtained by the Monte Carlo photon propagation simulation. As a result, we verify that SDF imaging allows the estimation of oxygen saturation of the individual vessels from virtual images using the average extinction coefficients considering the bandwidth of the illumination and the effect of the integration of the camera. PMID:26137368

  4. Effects of first myocardial infarction on left ventricular systolic and diastolic function with the use of mitral annular velocity determined by pulsed wave doppler tissue imaging.

    PubMed

    Alam, M; Wardell, J; Andersson, E; Samad, B A; Nordlander, R

    2000-05-01

    This study was undertaken to assess the effect of a first myocardial infarction (MI) on the systolic and diastolic velocity profiles of the mitral annulus determined by pulsed wave Doppler tissue imaging and thereby evaluate left ventricular (LV) function after MI. Seventy-eight patients with a first MI were examined before discharge. Peak systolic, peak early diastolic, and peak late diastolic velocities were recorded at 4 different sites on the mitral annulus corresponding to the septum, anterior, lateral, and inferior sites of the left ventricle. In addition, the amplitude of mitral annular motion at the 4 above LV sites, the ejection fraction, and conventional Doppler diastolic parameters were recorded. Nineteen age-matched healthy subjects served as controls. Compared with healthy subjects, the MI patients had a significantly reduced peak systolic velocity at the mitral annulus, especially at the infarction sites. A relatively good linear correlation was found between the ejection fraction and the mean systolic velocity from the 4 LV sites (r = 0.74, P <.001). The correlation was also good when the mean peak systolic mitral annular velocity was tested against the magnitude of the mean mitral annular motion (r = 0.77, P <.001). When the patients were divided into 2 different groups with respect to an ejection fraction > or =0.50 or <0.50, a cutoff point of mean systolic mitral annular velocity of > or =7.5 cm/s had a sensitivity of 79% and a specificity of 88% in predicting a preserved global LV systolic function. Similar to systolic velocities, the early diastolic velocity was also reduced, especially at the infarction sites. The peak mitral annular early diastolic velocity correlated well with both LV ejection fraction (r =.66, P <.001) and mean systolic mitral annular motion (r = 0.68, P <.001). However, no correlation existed between the early diastolic velocity and conventional diastolic Doppler parameters. The reduced peak systolic mitral annular velocity

  5. Correspondence - Characterization of the effective performance of a high-frequency annular-array-based imaging system using anechoic-pipe phantoms.

    PubMed

    Filoux, Erwan; Mamou, Jonathan; Moran, Carmel M; Pye, Stephen D; Ketterling, Jeffrey A

    2012-12-01

    A resolution integral (RI) method based on anechoic- pipe, tissue-mimicking phantoms was used to compare the detection capabilities of high-frequency imaging systems based on a single-element transducer, a state-of-the-art 256-element linear array, or a 5-element annular array. All transducers had a central frequency of 40 MHz with similar conventionally measured axial and lateral resolutions (about 50 and 85 μm, respectively). Using the RI metric, the annular array achieved the highest performance (RI = 60), followed by the linear array (RI = 47), and the single-element transducer (RI = 24). Results showed that the RI metric could be used to efficiently quantify the effective transducer performance and compare the image quality of different systems.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27357449

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

    PubMed

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

    2016-06-30

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  9. Laser-produced annular plasmas

    SciTech Connect

    Veloso, F.; Chuaqui, H.; Aliaga-Rossel, R.; Favre, M.; Mitchell, I. H.; Wyndham, E.

    2006-06-15

    A new technique is presented for the formation of annular plasmas on a metal surface with a high-power laser using a combination of axicon and converging lenses. The annular plasma formed on a titanium target in a chamber of hydrogen gas was investigated using schlieren imaging and Mach Zehnder interferometry. Expansion of the plasma was shown to be anisotropic with velocities of {approx}10{sup 3}-10{sup 4} m/s. Electron densities of 10{sup 18} cm{sup -3} were measured with radial profiles that confirm the presence of a hollow structure. The interferometric observations also show the presence of an inward shock wave traveling to the center of the annular plasma, which compresses the background neutrals, reaching a density around 18 times initial gas density, at 95 ns after the initial annular plasma is produced.

  10. Quantitative evaluation of annular bright-field phase images in STEM.

    PubMed

    Ishida, Takafumi; Kawasaki, Tadahiro; Tanji, Takayoshi; Ikuta, Takashi

    2015-04-01

    A phase reconstruction method based on multiple scanning transmission electron microscope (STEM) images was evaluated quantitatively using image simulations. The simulation results indicated that the phase shift caused by a single atom was proportional to the 0.6th power of the atomic number Z. For a thin SrTiO3 [001] crystal, the reconstructed phase at each atomic column increased according to the specimen thickness. The STEM phase images can quantify the oxygen vacancy concentration if the thickness is less than several nanometers.

  11. Laser Doppler velocimeter measurements and laser sheet imaging in an annular combustor model. M.S. Thesis, Final Report

    NASA Technical Reports Server (NTRS)

    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.

  12. Identification of the Position and Thickness of the First Annular Pulley in Sonographic Images.

    PubMed

    Yang, Tai-Hua; Lin, Yi-Hsun; Chuang, Bo-I; Chen, Hsin-Chen; Lin, Wei-Jr; Yang, Dee-Shan; Wang, Shyh-Hau; Sun, Yung-Nien; Jou, I-Ming; Kuo, Li-Chieh; Su, Fong-Chin

    2016-05-01

    The purpose was to identify the A1 pulley's exact location and thickness by comparing measurements from a clinical high-frequency ultrasound scanner system (CHUS), a customized high-frequency ultrasound imaging research system (HURS) and a digital caliper. Ten cadaveric hands were used. We explored the pulley by layers, inserted guide pins and scanned it with the CHUS. After identifying the pulley, we measured each long finger's thickness using the CHUS and excised the pulley to measure its thickness with a digital caliper and the HURS. The thin hypo-echoic layer was revealed to be the synovial fluid space, and the pulley appears hyper-echoic regardless of scan direction. We also defined the pulley's boundaries. Moreover, the CHUS provided a significantly lower measurement of the pulley's thickness than the digital caliper and HURS. Likewise, based on the digital caliper's measurement, the HURS had significantly lower mean absolute and relative errors than the CHUS.

  13. EUV Dark-Field Microscopy for Defect Inspection

    SciTech Connect

    Juschkin, L.; Maryasov, A.; Herbert, S.; Aretz, A.; Bergmann, K.; Lebert, R.

    2011-09-09

    An actinic EUV microscope for defect detection on mask blanks for operation in dark field using a table-top discharge-produced plasma source has been developed. Several test structures (pits and bumps) on multilayer mirrors were investigated by our Schwarzschild objective-based EUV microscope at 13.5-nm wavelength and then characterized with an atomic force microscope. Possible defect-detection limits with large field of view and moderate magnification are discussed in terms of required irradiation dose and system performance.

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Spatially multiplexed dark-field microspectrophotometry for nanoplasmonics

    PubMed Central

    Pini, V.; Kosaka, P. M.; Ruz, J. J.; Malvar, O.; Encinar, M.; Tamayo, J.; Calleja, M.

    2016-01-01

    Monitoring the effect of the substrate on the local surface plasmon resonance (LSPR) of metallic nanoparticles is key for deepening our understanding of light-matter interactions at the nanoscale. This coupling gives rise to shifts of the LSPR as well as changes in the scattering pattern shape. The problem requires of high-throughput techniques that present both high spatial and spectral resolution. We present here a technique, referred to as Spatially Multiplexed Micro-Spectrophotometry (SMMS), able to perform polarization-resolved spectral and spatial analysis of the scattered light over large surface areas. The SMMS technique provides three orders of magnitude faster spectroscopic analysis than conventional dark-field microspectrophotometry, with the capability for mapping the spatial distribution of the scattered light intensity with lateral resolution of 40 nm over surface areas of 0.02 mm2. We show polarization-resolved dark-field spectral analysis of hundreds of gold nanoparticles deposited on a silicon surface. The technique allows determining the effect of the substrate on the LSPR of single nanoparticles and dimers and their scattering patterns. This is applied for rapid discrimination and counting of monomers and dimers of nanoparticles. In addition, the diameter of individual nanoparticles can be rapidly assessed with 1 nm accuracy. PMID:26953042

  16. Valence EELS below the limit of inelastic delocalization using conical dark field EFTEM or Bessel beams.

    PubMed

    Stöger-Pollach, Michael; Schachinger, Thomas; Biedermann, Kati; Beyer, Volkhard

    2017-02-01

    In this experimental work we present novel methods to increase the spatial resolution of valence electron energy loss spectrometry (VEELS) investigations below the limit given by the inelastic delocalization. For this purpose we analyse a layer stack consisting of silicon/silicon-oxide/silicon-nitride/silicon-oxide/silicon (SONOS) with varying layer thickness down to the 2nm level. Using a combination of a conical illumination and energy filtered transmission electron microscopy we are able to identify the layers by using low energy losses. Employing Bessel beams we demonstrate that VEELS can be performed in dark-field conditions while simultaneously the Bessel beam increases the spatial resolution of the elastic image due to less sensitivity to the spherical aberration of the condenser lens system. The dark-field conditions also guarantee that only electrons are collected that have neither undergone an energy loss being due to the Cˇerenkov effect, nor due to the excitation of transition radiation or light guiding modes. We consequently are able to measure the optical properties of a 2.5nm thin oxide being sandwiched by the silicon substrate and a silicon-nitride layer.

  17. THE INFRARED ARRAY CAMERA DARK FIELD: FAR-INFRARED TO X-RAY DATA

    SciTech Connect

    Krick, J. E.; Surace, J. A.; Yan, L.; Lacy, M.; Thompson, D.; Ashby, M. L. N.; Hora, J.; Gorjian, V.; Frayer, D. T.; Egami, E.

    2009-11-01

    We present 20 band photometry from the far-IR to X-ray in the Spitzer Infrared Array Camera (IRAC) dark field. The bias for the near-IR camera on Spitzer is calibrated by observing a {approx}20' diameter 'dark' field near the north ecliptic pole roughly every two-to-three weeks throughout the mission duration of Spitzer. The field is unique for its extreme depth, low background, high quality imaging, time-series information, and accompanying photometry including data taken with Akari, Palomar, MMT, KPNO, Hubble, and Chandra. This serendipitous survey contains the deepest mid-IR data taken to date. This data set is well suited for studies of intermediate-redshift galaxy clusters, high-redshift galaxies, the first generation of stars, and the lowest mass brown dwarfs, among others. This paper provides a summary of the data characteristics and catalog generation from all bands collected to date as well as a discussion of photometric redshifts and initial and expected science results and goals. To illustrate the scientific potential of this unique data set, we also present here IRAC color-color diagrams.

  18. Dislocation tomography made easy: a reconstruction from ADF STEM images obtained using automated image shift correction

    NASA Astrophysics Data System (ADS)

    Sharp, J. H.; Barnard, J. S.; Kaneko, K.; Higashida, K.; Midgley, P. A.

    2008-08-01

    After previous work producing a successful 3D tomographic reconstruction of dislocations in GaN from conventional weak-beam dark-field (WBDF) images, we have reconstructed a cascade of dislocations in deformed and annealed silicon to a comparable standard using the more experimentally straightforward technique of STEM annular dark-field imaging (STEM ADF). In this mode, image contrast was much more consistent over the specimen tilt range than in conventional weak-beam dark-field imaging. Automatic acquisition software could thus restore the correct dislocation array to the field of view at each tilt angle, though manual focusing was still required. Reconstruction was carried out by sequential iterative reconstruction technique using FEI's Inspect3D software. Dislocations were distributed non-uniformly along cascades, with sparse areas between denser clumps in which individual dislocations of in-plane image width 24 nm could be distinguished in images and reconstruction. Denser areas showed more complicated stacking-fault contrast, hampering tomographic reconstruction. The general three-dimensional form of the denser areas was reproduced well, showing the dislocation array to be planar and not parallel to the foil surfaces.

  19. Strain measurement in ferromagnetic crystals using dark-field electron holography

    NASA Astrophysics Data System (ADS)

    Murakami, Yasukazu; Niitsu, Kodai; Kaneko, Syuhei; Tanigaki, Toshiaki; Sasaki, Taisuke; Akase, Zentaro; Shindo, Daisuke; Ohkubo, Tadakatsu; Hono, Kazuhiro

    2016-11-01

    This study proposes a method to separate the geometric phase shift due to lattice strain from the undesired phase information, resulting from magnetic fields that are superposed in the dark-field electron holography (DFEH) observations. Choosing a distinct wave vector for the Bragg reflection reversed the sense of the geometric phase shift, while the sense of the magnetic information remained unchanged. In the case of an Nd-Fe-B permanent magnet, once the unwanted signal was removed by data processing, the residual phase image revealed a strain map. Even though the applications of DFEH have thus far been limited to non-magnetic systems, the method proposed in this work is also applicable to strain measurements in various ferromagnetic systems.

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

    NASA Astrophysics Data System (ADS)

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

    2016-12-01

    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.

  1. Efficient elastic imaging of single atoms on ultrathin supports in a scanning transmission electron microscope.

    PubMed

    Hovden, Robert; Muller, David A

    2012-12-01

    Mono-atomic-layer membranes such as graphene offer new opportunities for imaging and detecting individual light atoms in transmission electron microscopes (TEM). For such applications where multiple scattering and diffraction effects are weak, we evaluate the detection efficiency and interpretability of single atom images for the most common detector geometries using quantitative quantum mechanical simulations. For well-resolved and atomically-thin specimens, the low angle annular dark field (LAADF) detector can provide a significant increase in signal-to-noise over other common detector geometries including annular bright field and incoherent bright field. This dramatically improves the visibility of organic specimens on atomic-layer membranes. Simulations of Adenosine Triphosphate (ATP) imaged under ideal conditions indicate the minimal dose requirements for elastic imaging by STEM or conventional TEM still exceed previously reported dose limits.

  2. Adaptive optics scanning ophthalmoscopy with annular pupils.

    PubMed

    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.

  3. Quantitative STEM Imaging of Order-Disorder Phenomena in Double Perovskite Thin Films

    NASA Astrophysics Data System (ADS)

    Esser, B. D.; Hauser, A. J.; Williams, R. E. A.; Allen, L. J.; Woodward, P. M.; Yang, F. Y.; McComb, D. W.

    2016-10-01

    Using aberration-corrected high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), we investigate ordering phenomena in epitaxial thin films of the double perovskite Sr2 CrReO6 . Experimental and simulated imaging and diffraction are used to identify antiphase domains in the films. Image simulation provides insight into the effects of atomic-scale ordering along the beam direction on HAADF-STEM intensity. We show that probe channeling results in ±20 % variation in intensity for a given composition, allowing 3D ordering information to be probed using quantitative STEM.

  4. Quantitative STEM Imaging of Order-Disorder Phenomena in Double Perovskite Thin Films.

    PubMed

    Esser, B D; Hauser, A J; Williams, R E A; Allen, L J; Woodward, P M; Yang, F Y; McComb, D W

    2016-10-21

    Using aberration-corrected high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM), we investigate ordering phenomena in epitaxial thin films of the double perovskite Sr_{2}CrReO_{6}. Experimental and simulated imaging and diffraction are used to identify antiphase domains in the films. Image simulation provides insight into the effects of atomic-scale ordering along the beam direction on HAADF-STEM intensity. We show that probe channeling results in ±20% variation in intensity for a given composition, allowing 3D ordering information to be probed using quantitative STEM.

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

    NASA Astrophysics Data System (ADS)

    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.

  6. Simulating realistic imaging conditions for in situ liquid microscopy

    SciTech Connect

    Welch, David A.; Faller, Roland; Evans, James E.; Browning, Nigel D.

    2013-12-01

    In situ transmission electron microscopy enables the imaging of biological cells, macromolecular protein complexes, nanoparticles, and other systems in a near-native environment. In order to improve interpretation of image contrast features and also predict ideal imaging conditions ahead of time, new virtual electron microscopic techniques are needed. A technique for virtual fluid-stage high-angle annular dark-field scanning transmission electron microscopy with the multislice method is presented that enables the virtual imaging of model fluid-stage systems composed of millions of atoms. The virtual technique is exemplified by simulating images of PbS nanoparticles under different imaging conditions and the results agree with previous experimental findings. General insight is obtained on the influence of the effects of fluid path length, membrane thickness, nanoparticle position, defocus and other microscope parameters on attainable image quality.

  7. Mechanically expandable annular seal

    DOEpatents

    Gilmore, R.F.

    1983-07-19

    A mechanically expandable annular reusable seal assembly to form an annular hermetic barrier between two stationary, parallel, and planar containment surfaces is described. A rotatable ring, attached to the first surface, has ring wedges resembling the saw-tooth array of a hole saw. Matching seal wedges are slidably attached to the ring wedges and have their motion restricted to be perpendicular to the second surface. Each seal wedge has a face parallel to the second surface. An annular elastomer seal has a central annular region attached to the seal wedges' parallel faces and has its inner and outer circumferences attached to the first surface. A rotation of the ring extends the elastomer seal's central region perpendicularly towards the second surface to create the fluid tight barrier. A counter rotation removes the barrier. 6 figs.

  8. Mechanically expandable annular seal

    DOEpatents

    Gilmore, Richard F.

    1983-01-01

    A mechanically expandable annular reusable seal assembly to form an annular hermetic barrier between two stationary, parallel, and planar containment surfaces. A rotatable ring, attached to the first surface, has ring wedges resembling the saw-tooth array of a hole saw. Matching seal wedges are slidably attached to the ring wedges and have their motion restricted to be perpendicular to the second surface. Each seal wedge has a face parallel to the second surface. An annular elastomer seal has a central annular region attached to the seal wedges' parallel faces and has its inner and outer circumferences attached to the first surface. A rotation of the ring extends the elastomer seal's central region perpendicularly towards the second surface to create the fluidtight barrier. A counterrotation removes the barrier.

  9. Annular nozzle engine technology

    NASA Technical Reports Server (NTRS)

    Martinez, AL

    1992-01-01

    The topics covered include: (1) driver rocket subsystem; (2) annular nozzle engine technology; (3) expansion-deflection nozzle; (4) aerospike-nozzled engine background; (5) aerospike testing; (6) linear aerospike; and (7) the combined cycle engine.

  10. Partial annular pancreas

    PubMed Central

    Jindal, Gunjan; Mittal, Amit; Singal, Rikki; Singal, Samita

    2016-01-01

    Annular pancreas is a developmental anomaly that can be associated with other conditions such as Down syndrome, duodenal atresia, and Hirschsprung disease. A band of pancreatic tissue, in continuity with the pancreatic head, completely or incompletely encircles the descending duodenum, sometimes assuming a “crocodile jaw” configuration. We present the case of an adult who presented with epigastric pain and vomiting and was found to have annular pancreas. PMID:27695176

  11. CellViCAM--Cell viability classification for animal cell cultures using dark field micrographs.

    PubMed

    Burgemeister, S; Nattkemper, T W; Noll, T; Hoffrogge, R; Flaschel, E

    2010-09-15

    Online monitoring of cell density and cell viability is a challenging but essential task to control and optimize biotechnical processes and is of particular interest for the growing field of animal cell cultures. For this purpose, we introduce an optical approach for automated cell detection and viability classification of suspended mammalian cells. Our proposed system CellViCAM is capable of evaluating dark field micrographs by means of several image processing and supervised machine learning techniques without the use of any dyes or fluorescent labeling. Using a human cell line as the reference culture, an efficient cell detection procedure has been established also enabling a cell density estimation. Furthermore, a comprehensive but reagent-free viability analysis, based on a semi-automatic training data generation, has been developed. By means of an extensive validation dataset we can show that the CellViCAM approach can be considered as an equivalent to staining-based methods and moreover, how it provides a technical platform for a more differentiated cell state classification into living, necrotic, early and late apoptosis.

  12. Diffraction contrast imaging using virtual apertures.

    PubMed

    Gammer, Christoph; Burak Ozdol, V; Liebscher, Christian H; Minor, Andrew M

    2015-08-01

    Two methods on how to obtain the full diffraction information from a sample region and the associated reconstruction of images or diffraction patterns using virtual apertures are demonstrated. In a STEM-based approach, diffraction patterns are recorded for each beam position using a small probe convergence angle. Similarly, a tilt series of TEM dark-field images is acquired. The resulting datasets allow the reconstruction of either electron diffraction patterns, or bright-, dark- or annular dark-field images using virtual apertures. The experimental procedures of both methods are presented in the paper and are applied to a precipitation strengthened and creep deformed ferritic alloy with a complex microstructure. The reconstructed virtual images are compared with conventional TEM images. The major advantage is that arbitrarily shaped virtual apertures generated with image processing software can be designed without facing any physical limitations. In addition, any virtual detector that is specifically designed according to the underlying crystal structure can be created to optimize image contrast.

  13. Improved Diagnostics by Assessing the Micromorphology of Breast Calcifications via X-Ray Dark-Field Radiography

    NASA Astrophysics Data System (ADS)

    Scherer, Kai; Braig, Eva; Ehn, Sebastian; Schock, Jonathan; Wolf, Johannes; Birnbacher, Lorenz; Chabior, Michael; Herzen, Julia; Mayr, Doris; Grandl, Susanne; Sztrókay-Gaul, Anikó; Hellerhoff, Karin; Pfeiffer, Franz

    2016-11-01

    Breast microcalcifications play an essential role in the detection and evaluation of early breast cancer in clinical diagnostics. However, in digital mammography, microcalcifications are merely graded with respect to their global appearance within the mammogram, while their interior microstructure remains spatially unresolved and therefore not considered in cancer risk stratification. In this article, we exploit the sub-pixel resolution sensitivity of X-ray dark-field contrast for clinical microcalcification assessment. We demonstrate that the micromorphology, rather than chemical composition of microcalcification clusters (as hypothesised by recent literature), determines their absorption and small-angle scattering characteristics. We show that a quantitative classification of the inherent microstructure as ultra-fine, fine, pleomorphic and coarse textured is possible. Insights underlying the micromorphological nature of breast calcifications are verified by comprehensive high-resolution micro-CT measurements. We test the determined microtexture of microcalcifications as an indicator for malignancy and demonstrate its potential to improve breast cancer diagnosis, by providing a non-invasive tool for sub-resolution microcalcification assessment. Our results indicate that dark-field imaging of microcalcifications may enhance the diagnostic validity of current microcalcification analysis and reduce the number of invasive procedures.

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

    PubMed

    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.

  15. Improved Diagnostics by Assessing the Micromorphology of Breast Calcifications via X-Ray Dark-Field Radiography

    PubMed Central

    Scherer, Kai; Braig, Eva; Ehn, Sebastian; Schock, Jonathan; Wolf, Johannes; Birnbacher, Lorenz; Chabior, Michael; Herzen, Julia; Mayr, Doris; Grandl, Susanne; Sztrókay-Gaul, Anikó; Hellerhoff, Karin; Pfeiffer, Franz

    2016-01-01

    Breast microcalcifications play an essential role in the detection and evaluation of early breast cancer in clinical diagnostics. However, in digital mammography, microcalcifications are merely graded with respect to their global appearance within the mammogram, while their interior microstructure remains spatially unresolved and therefore not considered in cancer risk stratification. In this article, we exploit the sub-pixel resolution sensitivity of X-ray dark-field contrast for clinical microcalcification assessment. We demonstrate that the micromorphology, rather than chemical composition of microcalcification clusters (as hypothesised by recent literature), determines their absorption and small-angle scattering characteristics. We show that a quantitative classification of the inherent microstructure as ultra-fine, fine, pleomorphic and coarse textured is possible. Insights underlying the micromorphological nature of breast calcifications are verified by comprehensive high-resolution micro-CT measurements. We test the determined microtexture of microcalcifications as an indicator for malignancy and demonstrate its potential to improve breast cancer diagnosis, by providing a non-invasive tool for sub-resolution microcalcification assessment. Our results indicate that dark-field imaging of microcalcifications may enhance the diagnostic validity of current microcalcification analysis and reduce the number of invasive procedures. PMID:27841341

  16. GALAXY CLUSTERS IN THE IRAC DARK FIELD. II. MID-INFRARED SOURCES

    SciTech Connect

    Krick, J. E.; Surace, J. A.; Yan, L.; Thompson, D.; Ashby, M. L. N.; Hora, J. L.; Gorjian, V.

    2009-07-20

    We present infrared (IR) luminosities, star formation rates (SFR), colors, morphologies, locations, and active galactic nuclei (AGNs) properties of 24 {mu}m detected sources in photometrically detected high-redshift clusters in order to understand the impact of environment on star formation (SF) and AGN evolution in cluster galaxies. We use three newly identified z = 1 clusters selected from the IRAC dark field; the deepest ever mid-IR survey with accompanying, 14 band multiwavelength data including deep Hubble Space Telescope imaging and deep wide-area Spitzer MIPS 24 {mu}m imaging. We find 90 cluster members with MIPS detections within two virial radii of the cluster centers, of which 17 appear to have spectral energy distributions dominated by AGNs and the rest dominated by SF. We find that 43% of the star-forming sample have IR luminosities L{sub IR} > 10{sup 11} L{sub sun} (luminous IR galaxies). The majority of sources (81%) are spirals or irregulars. A large fraction (at least 25%) show obvious signs of interactions. The MIPS-detected member galaxies have varied spatial distributions as compared to the MIPS-undetected members with one of the three clusters showing SF galaxies being preferentially located on the cluster outskirts, while the other two clusters show no such trend. Both the AGN fraction and the summed SFR of cluster galaxies increase from redshift zero to one, at a rate that is a few times faster in clusters than over the same redshift range in the field. Cluster environment does have an effect on the evolution of both AGN fraction and SFR from redshift one to the present, but does not affect the IR luminosities or morphologies of the MIPS sample. SF happens in the same way regardless of environment making MIPS sources look the same in the cluster and field, however the cluster environment does encourage a more rapid evolution with time as compared to the field.

  17. Specimen illumination apparatus with optical cavity for dark field illumination

    DOEpatents

    Pinkel, Daniel; Sudar, Damir; Albertson, Donna

    1999-01-01

    An illumination apparatus with a specimen slide holder, an illumination source, an optical cavity producing multiple reflection of illumination light to a specimen comprising a first and a second reflective surface arranged to achieve multiple reflections of light to a specimen is provided. The apparatus can further include additional reflective surfaces to achieve the optical cavity, a slide for mounting the specimen, a coverslip which is a reflective component of the optical cavity, one or more prisms for directing light within the optical cavity, antifading solutions for improving the viewing properties of the specimen, an array of materials for analysis, fluorescent components, curved reflective surfaces as components of the optical cavity, specimen detection apparatus, optical detection equipment, computers for analysis of optical images, a plane polarizer, fiberoptics, light transmission apertures, microscopic components, lenses for viewing the specimen, and upper and lower mirrors above and below the specimen slide as components of the optical cavity. Methods of using the apparatus are also provided.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Segmented annular combustor

    DOEpatents

    Reider, Samuel B.

    1979-01-01

    An industrial gas turbine engine includes an inclined annular combustor made up of a plurality of support segments each including inner and outer walls of trapezoidally configured planar configuration extents and including side flanges thereon interconnected by means of air cooled connector bolt assemblies to form a continuous annular combustion chamber therebetween and wherein an air fuel mixing chamber is formed at one end of the support segments including means for directing and mixing fuel within a plenum and a perforated header plate for directing streams of air and fuel mixture into the combustion chamber; each of the outer and inner walls of each of the support segments having a ribbed lattice with tracks slidably supporting porous laminated replaceable panels and including pores therein for distributing combustion air into the combustion chamber while cooling the inner surface of each of the panels by transpiration cooling thereof.

  20. Performance and Image Analysis of the Aberration Corrected Hitachi HD-2700C Stem

    SciTech Connect

    Inada, H.; Zhu, Y.; Wu, L.; Wall, J.; Su, D.

    2009-03-01

    We report the performance of the first aberration-corrected scanning transmission electron microscope (STEM) manufactured by Hitachi. We describe its unique features and versatile capabilities in atomic-scale characterization and its applications in materials research. We also discuss contrast variation of the STEM images obtained from different annular dark-field (ADF) detectors of the instrument, and the increased complexity in contrast interpretation and quantification due to the increased convergent angles of the electron probe associated with the aberration corrector. We demonstrate that the intensity of atomic columns in an ADF image depends strongly on a variety of imaging parameters, sample thickness, as well as the nuclear charge and the deviation from their periodic position of the atoms we are probing. Image simulations are often required to correctly interpret the atomic structure of an ADF-STEM image.

  1. Atomic resolution ADF-STEM imaging of organic molecular crystal of halogenated copper phthalocyanine.

    PubMed

    Haruta, Mitsutaka; Yoshida, Kaname; Kurata, Hiroki; Isoda, Seiji

    2008-05-01

    Annular dark-field (ADF) scanning transmission electron microscopy (STEM) measurements are demonstrated for the first time to be applicable for acquiring Z-contrast images of organic molecules at atomic resolution. High-angle ADF imaging by STEM is a new technique that provides incoherent high-resolution Z-contrast images for organic molecules. In the present study, low-angle ADF-STEM is successfully employed to image the molecular crystal structure of hexadecachloro-Cu-phthalocyanine (Cl16-CuPc), an organic molecule. The structures of CuPc derivatives (polyhalogenated CuPc with Br and Cl) are determined quantitatively using the same technique to determine the occupancy of halogens at each chemical site. By comparing the image contrasts of atomic columns, the occupancy of Br is found to be ca. 56% at the inner position, slightly higher than that for random substitution and in good agreement with previous TEM results.

  2. Non-rigid registration and non-local principle component analysis to improve electron microscopy spectrum images

    NASA Astrophysics Data System (ADS)

    Yankovich, Andrew B.; Zhang, Chenyu; Oh, Albert; Slater, Thomas J. A.; Azough, Feridoon; Freer, Robert; Haigh, Sarah J.; Willett, Rebecca; Voyles, Paul M.

    2016-09-01

    Image registration and non-local Poisson principal component analysis (PCA) denoising improve the quality of characteristic x-ray (EDS) spectrum imaging of Ca-stabilized Nd2/3TiO3 acquired at atomic resolution in a scanning transmission electron microscope. Image registration based on the simultaneously acquired high angle annular dark field image significantly outperforms acquisition with a long pixel dwell time or drift correction using a reference image. Non-local Poisson PCA denoising reduces noise more strongly than conventional weighted PCA while preserving atomic structure more faithfully. The reliability of and optimal internal parameters for non-local Poisson PCA denoising of EDS spectrum images is assessed using tests on phantom data.

  3. Super-resolution of fluorescence-free plasmonic nanoparticles using enhanced dark-field illumination based on wavelength-modulation

    SciTech Connect

    Zhang, Peng; Lee, Seungah; Yu, Hyunung; Fang, Ning; Ho Kang, Seong

    2015-06-15

    Super-resolution imaging of fluorescence-free plasmonic nanoparticles (NPs) was achieved using enhanced dark-field (EDF) illumination based on wavelength-modulation. Indistinguishable adjacent EDF images of 103-nm gold nanoparticles (GNPs), 40-nm gold nanorods (GNRs), and 80-nm silver nanoparticles (SNPs) were modulated at their wavelengths of specific localized surface plasmon scattering. The coordinates (x, y) of each NP were resolved by fitting their point spread functions with a two-dimensional Gaussian. The measured localization precisions of GNPs, GNRs, and SNPs were 2.5 nm, 5.0 nm, and 2.9 nm, respectively. From the resolved coordinates of NPs and the corresponding localization precisions, super-resolution images were reconstructed. Depending on the spontaneous polarization of GNR scattering, the orientation angle of GNRs in two-dimensions was resolved and provided more elaborate localization information. This novel fluorescence-free super-resolution method was applied to live HeLa cells to resolve NPs and provided remarkable subdiffraction limit images.

  4. Super-resolution of fluorescence-free plasmonic nanoparticles using enhanced dark-field illumination based on wavelength-modulation

    DOE PAGES

    Zhang, Peng; Lee, Seungah; Yu, Hyunung; ...

    2015-06-15

    Super-resolution imaging of fluorescence-free plasmonic nanoparticles (NPs) was achieved using enhanced dark-field (EDF) illumination based on wavelength-modulation. Indistinguishable adjacent EDF images of 103-nm gold nanoparticles (GNPs), 40-nm gold nanorods (GNRs), and 80-nm silver nanoparticles (SNPs) were modulated at their wavelengths of specific localized surface plasmon scattering. The coordinates (x, y) of each NP were resolved by fitting their point spread functions with a two-dimensional Gaussian. The measured localization precisions of GNPs, GNRs, and SNPs were 2.5 nm, 5.0 nm, and 2.9 nm, respectively. From the resolved coordinates of NPs and the corresponding localization precisions, super-resolution images were reconstructed. Depending onmore » the spontaneous polarization of GNR scattering, the orientation angle of GNRs in two-dimensions was resolved and provided more elaborate localization information. This novel fluorescence-free super-resolution method was applied to live HeLa cells to resolve NPs and provided remarkable subdiffraction limit images.« less

  5. Dark-field spectroscopy of plasmon resonance in metal nanoislands: effect of shape and light polarization

    NASA Astrophysics Data System (ADS)

    Babich, E. S.; Scherbak, S. A.; Heisler, F.; Chervinskii, S. D.; Samusev, A. K.; Lipovskii, A. A.

    2016-11-01

    We present the experimental dark-field scattering studies and the simulation of plasmonic properties of isolated silver nanoislands. The nanoislands were fabricated on a soda- lime glass substrate using silver-sodium ion exchange, subsequent thermal poling and annealing of the processed glass substrate in hydrogen. The morphology of the nanoislands was characterized with atomic force microscopy and scanning electron microscopy; the dimensions were 100-180 nm in base and 80-160 nm in height. We measured and modeled dark-field scattering spectra of the silver hemiellipsoidal nanoparticles differing in size and shape. The SPR position varied from 450 nm to 730 nm depending on the particle shape and dimensions. Both experiments and simulation showed a red shift of the SPR for bigger nanoislands of the same shape. Losing the axial symmetry in nanoislands resulted in the resonance splitting, while their elongation led to an increase in the scattering of p-polarized light.

  6. Endoscopic measurements using a panoramic annular lens

    NASA Technical Reports Server (NTRS)

    Gilbert, John A.; Matthys, Donald R.

    1992-01-01

    The objective of this project was to design, build, demonstrate, and deliver a prototype system for making measurements within cavities. The system was to utilize structured lighting as the means for making measurements and was to rely on a stationary probe, equipped with a unique panoramic annular lens, to capture a cylindrical view of the illuminated cavity. Panoramic images, acquired with a digitizing camera and stored in a desk top computer, were to be linearized and analyzed by mouse-driven interactive software.

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

    SciTech Connect

    Vittoria, Fabio A. Diemoz, Paul C.; Olivo, Alessandro; Kallon, Gibril K. N.; Basta, Dario; Endrizzi, Marco; Robinson, Ian K.

    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.

  8. Annular recuperator design

    DOEpatents

    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.

  9. Hybrid statistics-simulations based method for atom-counting from ADF STEM images.

    PubMed

    De Wael, Annelies; De Backer, Annick; Jones, Lewys; Nellist, Peter D; Van Aert, Sandra

    2017-01-25

    A hybrid statistics-simulations based method for atom-counting from annular dark field scanning transmission electron microscopy (ADF STEM) images of monotype crystalline nanostructures is presented. Different atom-counting methods already exist for model-like systems. However, the increasing relevance of radiation damage in the study of nanostructures demands a method that allows atom-counting from low dose images with a low signal-to-noise ratio. Therefore, the hybrid method directly includes prior knowledge from image simulations into the existing statistics-based method for atom-counting, and accounts in this manner for possible discrepancies between actual and simulated experimental conditions. It is shown by means of simulations and experiments that this hybrid method outperforms the statistics-based method, especially for low electron doses and small nanoparticles. The analysis of a simulated low dose image of a small nanoparticle suggests that this method allows for far more reliable quantitative analysis of beam-sensitive materials.

  10. Effect of chromatic aberration on atomic-resolved spherical aberration corrected STEM images.

    PubMed

    Kuramochi, Koji; Yamazaki, Takashi; Kotaka, Yasutoshi; Ohtsuka, Masahiro; Hashimoto, Iwao; Watanabe, Kazuto

    2009-12-01

    The effect of the chromatic aberration (C(c)) coefficient in a spherical aberration (C(s))- corrected electromagnetic lens on high-resolution high-angle annular dark field (HAADF) scanning transmission electron microscope (STEM) images is explored in detail. A new method for precise determination of the C(c) coefficient is demonstrated, requiring measurement of an atomic-resolution one-frame through-focal HAADF STEM image. This method is robust with respect to instrumental drift, sample thickness, all lens parameters except C(c), and experimental noise. It is also demonstrated that semi-quantitative structural analysis on the nanometer scale can be achieved by comparing experimental C(s)- corrected HAADF STEM images with their corresponding simulated images when the effects of the C(c) coefficient and spatial incoherence are included.

  11. Minerals and aligned collagen fibrils in tilapia fish scales: structural analysis using dark-field and energy-filtered transmission electron microscopy and electron tomography.

    PubMed

    Okuda, Mitsuhiro; Ogawa, Nobuhiro; Takeguchi, Masaki; Hashimoto, Ayako; Tagaya, Motohiro; Chen, Song; Hanagata, Nobutaka; Ikoma, Toshiyuki

    2011-10-01

    The mineralized structure of aligned collagen fibrils in a tilapia fish scale was investigated using transmission electron microscopy (TEM) techniques after a thin sample was prepared using aqueous techniques. Electron diffraction and electron energy loss spectroscopy data indicated that a mineralized internal layer consisting of aligned collagen fibrils contains hydroxyapatite crystals. Bright-field imaging, dark-field imaging, and energy-filtered TEM showed that the hydroxyapatite was mainly distributed in the hole zones of the aligned collagen fibrils structure, while needle-like materials composed of calcium compounds including hydroxyapatite existed in the mineralized internal layer. Dark-field imaging and three-dimensional observation using electron tomography revealed that hydroxyapatite and needle-like materials were mainly found in the matrix between the collagen fibrils. It was observed that hydroxyapatite and needle-like materials were preferentially distributed on the surface of the hole zones in the aligned collagen fibrils structure and in the matrix between the collagen fibrils in the mineralized internal layer of the scale.

  12. Direct observation of nanometer-scale strain field around CoSi{sub 2}/Si interface using scanning moiré fringe imaging

    SciTech Connect

    Kim, Suhyun; Jung, Younheum; Jung Kim, Joong; Byun, Gwangseon; Lee, Sunyoung; Lee, Heabum

    2014-04-21

    We report the use of scanning moiré fringe (SMF) imaging through high-angle annular dark-field scanning transmission electron microscopy (STEM) to measure the strain field around a CoSi{sub 2} contact embedded in the source and drain (S/D) region of a transistor. The atomic arrangement of the CoSi{sub 2}/Si (111) interface was determined from the high-resolution (HR)-STEM images, and the strain field formed around the S/D region was revealed by nanometer-scale SMFs appearing in the STEM image. In addition, we showed that the strain field in the S/D region measured by SMF imaging agreed with results obtained via peak-pairs analysis of HR-STEM images.

  13. Endoscopic inspection using a panoramic annular lens

    NASA Technical Reports Server (NTRS)

    Gilbert, John A.; Matthys, Donald R.

    1991-01-01

    The objective of this one year study was to design, build, and demonstrate a prototype system for cavity inspection. A cylindrical view of the cavity interior was captured in real time through a compound lens system consisting of a unique panoramic annular lens and a collector lens. Images, acquired with a digitizing camera and stored in a desktop computer, were manipulated using image processing software to aid in visual inspection and qualitative analysis. A detailed description of the lens and its applications is given.

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

    SciTech Connect

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

    2014-06-23

    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.

  15. Axisymmetric annular curtain stability

    NASA Astrophysics Data System (ADS)

    Ahmed, Zahir U.; Khayat, Roger E.; Maissa, Philippe; Mathis, Christian

    2012-06-01

    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.

  16. Icosahedral stereographic projections in three dimensions for use in dark field TEM.

    PubMed

    Bourdillon, Antony J

    2013-08-01

    Thermodynamics require that rapidly cooled crystals and quasicrystals are relatively defective. Yet, without convenient 3-dimensional indexation both at crystal poles and in diffraction planes, or Kikuchi maps, it is difficult to identify the defects by dark field transmission electron microscopy. For two phase Al6Mn, these maps are derived. They relate i-Al6Mn to the standard face centered cubic, matrix crystals. An example of their usefulness in determining interfacial characteristics is described. Indices are integral powers on an irrational number.

  17. Scanning moiré fringe imaging by scanning transmission electron microscopy.

    PubMed

    Su, Dong; Zhu, Yimei

    2010-02-01

    A type of artificial contrast found in annular dark-field imaging is generated by spatial interference between the scanning grating of the electron beam and the specimen atomic lattice. The contrast is analogous to moiré fringes observed in conventional transmission electron microscopy. We propose using this scanning interference for retrieving information about the atomic lattice structure at medium magnifications. Compared with the STEM atomic imaging at high magnifications, this approach might have several advantages including easy observation of lattice discontinuities and reduction of image degradation from carbon contamination and beam damage. Application of the technique to reveal the Burgers vector of misfit dislocations at the interface of epitaxial films is demonstrated and its potential for studying strain fields is discussed.

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

    PubMed Central

    Simons, H.; King, A.; Ludwig, W.; Detlefs, C.; Pantleon, W.; Schmidt, S.; Snigireva, I.; Snigirev, A.; Poulsen, H. F.

    2015-01-01

    Many physical and mechanical properties of crystalline materials depend strongly on their internal structure, which is typically organized into grains and domains on several length scales. Here we present dark-field X-ray microscopy; a non-destructive microscopy technique for the three-dimensional mapping of orientations and stresses on lengths scales from 100 nm to 1 mm 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 (for example, positioned at interfaces) is crucial to the performance and lifetime of macro-scale devices and components thereof. PMID:25586429

  19. An annular pancreas associated with carcinoma of the papilla of Vater: report of a case.

    PubMed

    Yazawa, Naoki; Imaizumi, Toshihide; Furukawa, Daisuke; Matsuyama, Masahiro; Gunji, Hisashi; Kato, Kenichiro; Tobita, Kosuke; Nakagohri, Toshio; Makuuchi, Hiroyasu; Hirabayashi, Kenichi; Ogoshi, Kyoji

    2012-05-01

    An annular pancreas is an uncommon congenital anomaly that usually presents early in childhood. Malignancy in the setting of an annular pancreas is unusual. We herein report a case of annular pancreas with carcinoma of the papilla of Vater. A 59-year-old man presented with epigastric discomfort and was referred to us after gastroduodenal endoscopy showed a tumor of the papilla of Vater. Preoperative imaging showed the pancreatic parenchyma encircling the descending duodenum and a tumor at the papilla of Vater. A pancreaticoduodenectomy was performed for the annular pancreas and the ampullary tumor. Histological examination confirmed a complete annular pancreas and carcinoma in situ of the papilla of Vater. We also provide a review of the reported cases of an annular pancreas with periampullary neoplasms and discuss the clinical characteristics of this anomaly.

  20. The Langley Annular Transonic Tunnel

    NASA Technical Reports Server (NTRS)

    Habel, Louis W; Henderson, James H; Miller, Mason F

    1952-01-01

    Report describes the development of the Langley annular transonic tunnel, a facility in which test Mach numbers from 0.6 to slightly over 1.0 are achieved by rotating the test model in an annular passage between two concentric cylinders. Data obtained for two-dimensional airfoil models in the Langley annular transonic tunnel at subsonic and sonic speeds are shown to be in reasonable agreement with experimental data from other sources and with theory when comparisons are made for nonlifting conditions or for equal normal-force coefficients rather than for equal angles of attack. The trends of pressure distributions obtained from measurements in the Langley annular transonic tunnel are consistent with distributions calculated for Prandtl-Meyer flow.

  1. 1-to 10-keV x-ray backlighting of annular wire arrays on the Sandia Z-machine using bent-crystal imaging techniques.

    SciTech Connect

    Rambo, Patrick K.; Wenger, David Franklin; Bennett, Guy R.; Sinars, Daniel Brian; Smith, Ian Craig; Porter, John Larry, Jr.; Cuneo, Michael Edward; Rovang, Dean Curtis; Anderson, Jessica E.

    2003-07-01

    Annular wire array implosions on the Sandia Z-machine can produce >200 TW and 1-2 MJ of soft x rays in the 0.1-10 keV range. The x-ray flux and debris in this environment present significant challenges for radiographic diagnostics. X-ray backlighting diagnostics at 1865 and 6181 eV using spherically-bent crystals have been fielded on the Z-machine, each with a {approx}0.6 eVspectral bandpass, 10 {micro}m spatial resolution, and a 4 mm by 20mm field of view. The Z-Beamlet laser, a 2-TW, 2-kJ Nd:glass laser({lambda} = 527 nm), is used to produce 0.1-1 J x-ray sources for radiography. The design, calibration, and performance of these diagnostics is presented.

  2. An auto-tuning method for focusing and astigmatism correction in HAADF-STEM, based on the image contrast transfer function.

    PubMed

    Baba, N; Terayama, K; Yoshimizu, T; Ichise, N; Tanaka, N

    2001-01-01

    An auto-tuning method for high-angle annular detector dark field scanning transmission electron microscopy (HAADF-STEM) is proposed which corrects the defocus to the optimum Scherzer focus and compensates the astigmatism. Because the method is based on the image contrast transfer function formulated for the HAADF-STEM, the defocus and the astigmatism are accurately measured from input of two different defocus images. The method is designed to work independent of object function in the linear imaging model by analysing the spectral ratio between two Fourier spectra of their images, which is useful for cases where the spectrum of object function is not uniformly spread out over the reciprocal space. The method was preliminarily tested in a Hitachi HD-2000 STEM, and successful results of the auto-tunings from the viewpoint of verification of the algorithm were obtained using general specimens of Au fine particles and a thin section of a semiconductor device.

  3. Statistical distribution of single atoms and clusters of supported Au catalyst analyzed by global high-resolution HAADF-STEM observation with morphological image-processing operation.

    PubMed

    Yamamoto, Yuta; Arai, Shigeo; Esaki, Akihiko; Ohyama, Junya; Satsuma, Atsushi; Tanaka, Nobuo

    2014-06-01

    We have developed a quantitative particle size analytical method at the single atomic level employing electron microscopy and image processing for the investigation of supported metal catalysts. In the present study, a supported gold (Au) catalyst containing sub-nano clusters and individual atoms was globally observed by high-resolution high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) using spherical aberration (Cs)-corrected TEM. To fully extract structural information of the Au clusters and individual atoms from the HAADF-STEM images, a morphological image-processing operation was applied. The resulting mean particle size was in good agreement with particle sizes estimated from average information provided by X-ray absorption fine structure analysis. It is demonstrated that the present HAADF-STEM image analysis gives a quantitative particle size distribution measurement of supported Au clusters and individual atoms.

  4. Portal Annular Pancreas: A Rare and Overlooked Anomaly

    PubMed Central

    Mittal, Puneet; Gupta, Ranjana; Mittal, Amit; Ahmed, Arshad

    2017-01-01

    Summary Background Portal annular pancreas is a rare pancreatic developmental anomaly which is often overlooked at imaging, and often diagnosed retrospectively when it is detected incidentally at the time of surgery. Although the anomaly itself is asymptomatic, it becomes important in cases where pancreatic resection/anastomosis is planned, because of varying ductal anatomy, risk of ductal injury and increased risk of postoperative pancreatic fistula formation. Case Report We present imaging findings in a case of portal annular pancreas in a 45-year-old male patient. Conclusions Portal annular pancreas is a rare and often neglected pancreatic anomaly due to a lack of awareness of this entity. With the advent of MDCT and MRI, accurate preoperative diagnosis of this condition is possible. PMID:28203311

  5. Dynamic-Receive Focusing with High-Frequency Annular Arrays

    NASA Astrophysics Data System (ADS)

    Ketterling, J. A.; Mamou, J.; Silverman, R. H.

    High-frequency ultrasound is commonly employed for ophthalmic and small-animal imaging because of the fine-resolution images it affords. Annular arrays allow improved depth of field and lateral resolution versus commonly used single-element, focused transducers. The best image quality from an annular array is achieved by using synthetic transmit-to-receive focusing while utilizing data from all transmit-to-receive element combinations. However, annular arrays must be laterally scanned to form an image and this requires one pass for each of the array elements when implementing full synthetic transmit-to-receive focusing. A dynamic-receive focusing approach permits a single pass, although at a sacrifice of depth of field and lateral resolution. A five-element, 20-MHz annular array is examined to determine the acoustic beam properties for synthetic and dynamic-receive focusing. A spatial impulse response model is used to simulate the acoustic beam properties for each focusing case and then data acquired from a human eye-bank eye are processed to demonstrate the effect of each approach on image quality.

  6. Dark-field microspectroscopic analysis of gold nanorods in spiral Ganglion neurons

    NASA Astrophysics Data System (ADS)

    Yong, J.; Brown, W. G. A.; Needham, K.; Nayagam, B. A.; Yu, A.; McArthur, S. L.; Stoddart, P. R.

    2013-12-01

    Heterogeneous samples of spiral ganglion neuron primary cells were incubated with gold nanorods in order to investigate the photothermal processes induced by exposure to 780 nm laser light. Dark-field microspectroscopy was used to analyze the distribution and spectrum of nanorods in the neurons. The scattering data showed a typical gold nanorod spectrum, while a shift in the peak position suggested changes in the refractive index of the nanorod environment. The relationship between gold nanorods distribution and local temperature has also been examined with an open pipette microelectrode placed in the surrounding bath of the neurons. These temperature measurements confirm that the gold nanorods provide efficient localized heating under 780 nm laser exposure.

  7. Phase reconstruction in annular bright-field scanning transmission electron microscopy.

    PubMed

    Ishida, Takafumi; Kawasaki, Tadahiro; Tanji, Takayoshi; Kodama, Tetsuji; Matsutani, Takaomi; Ogai, Keiko; Ikuta, Takashi

    2015-04-01

    A novel technique for reconstructing the phase shifts of electron waves was applied to Cs-corrected scanning transmission electron microscopy (STEM). To realize this method, a new STEM system equipped with an annular aperture, annularly arrayed detectors and an arrayed image processor has been developed and evaluated in experiments. We show a reconstructed phase image of graphite particles and demonstrate that this new method works effectively for high-resolution phase imaging.

  8. Design of wavefront coding optical system with annular aperture

    NASA Astrophysics Data System (ADS)

    Chen, Xinhua; Zhou, Jiankang; Shen, Weimin

    2016-10-01

    Wavefront coding can extend the depth of field of traditional optical system by inserting a phase mask into the pupil plane. In this paper, the point spread function (PSF) of wavefront coding system with annular aperture are analyzed. Stationary phase method and fast Fourier transform (FFT) method are used to compute the diffraction integral respectively. The OTF invariance is analyzed for the annular aperture with cubic phase mask under different obscuration ratio. With these analysis results, a wavefront coding system using Maksutov-Cassegrain configuration is designed finally. It is an F/8.21 catadioptric system with annular aperture, and its focal length is 821mm. The strength of the cubic phase mask is optimized with user-defined operand in Zemax. The Wiener filtering algorithm is used to restore the images and the numerical simulation proves the validity of the design.

  9. Epidermal activity in annular dermatophytosis.

    PubMed

    Berk, S H; Penneys, N S; Weinstein, G D

    1976-04-01

    In five patients with annular tinea corporis, the tritated thymidine labeling indexes were determined in the rim, center, and intermediate areas of the lesion and compared with normal skin. Labeling indexes at the rim were much higher than those of normal skin (mean, 4.2 times). Labeling indexes elsewhere in the lesion were not significantly different from those of normal skin. Histologic examination showed epidermal thickening in all areas of the lesion as compared with normal skin. This study suggests that there is an increased epidermal turnover at the rim of annular dermatophytosis that may be important in the pathophysiology and morphogenesis of such lesions.

  10. Annular Eclipse as Seen by Hinode

    NASA Video Gallery

    This timelapse shows an annular eclipse as seen by JAXA's Hinode satellite on Jan. 4, 2011. An annular eclipse occurs when the moon, slightly more distant from Earth than on average, moves directly...

  11. Reproducible strain measurement in electronic devices by applying integer multiple to scanning grating in scanning moiré fringe imaging

    SciTech Connect

    Kim, Suhyun Jung, Younheum; Kim, Joong Jung; Lee, Sunyoung; Lee, Haebum; Kondo, Yukihito

    2014-10-15

    Scanning moiré fringe (SMF) imaging by high-angle annular dark field scanning transmission electron microscopy was used to measure the strain field in the channel of a transistor with a CoSi{sub 2} source and drain. Nanometer-scale SMFs were formed with a scanning grating size of d{sub s} at integer multiples of the Si crystal lattice spacing d{sub l} (d{sub s} ∼ nd{sub l}, n = 2, 3, 4, 5). The moiré fringe formula was modified to establish a method for quantifying strain measurement. We showed that strain fields in a transistor measured by SMF images were reproducible with an accuracy of 0.02%.

  12. IMAGE-WARP: a real-space restoration method for high-resolution STEM images using quantitative HRTEM analysis.

    PubMed

    Recnik, Aleksander; Möbus, Günter; Sturm, Saso

    2005-07-01

    We have developed a new method for processing distorted high-resolution scanning transmission electron microscopy (STEM) images. The method is based on finding the displaced vertices in the experimental STEM image and warping to geometrically correct reference grid of the object. As a reference grid for warping a structural model obtained using a high-resolution transmission electron microscopy (HRTEM) analysis of the area of interest is utilised. Combined with quantitative HRTEM analysis the IMAGE-WARP method provides a real-space restoration of high-resolution high-angle annular dark-field (HAADF) STEM images without affecting the original Z-contrast information. The method can be applied to extract valuable compositional atomic-column data from any HAADF-STEM image of any kind of bulk crystals with local occupancy or chemistry fluctuations, stacking faults, special grain boundaries or interfaces, for which we have an available structural model. After the warping, distortion-corrected images can be further enhanced using conventional image-filtering techniques, and finally quantified with HAADF-STEM image simulations. The applicability of the IMAGE-WARP method was illustrated using experimental HAADF-STEM images of a strontium titanate crystal disrupted with a Ruddlesden-Popper-type antiphase boundary.

  13. Quantitative Z-contrast imaging in the scanning transmission electron microscope with size-selected clusters

    NASA Astrophysics Data System (ADS)

    Wang, Z. W.; Li, Z. Y.; Park, S. J.; Abdela, A.; Tang, D.; Palmer, R. E.

    2011-08-01

    This paper describes a new approach of quantification of annular-dark-field or Z-contrast image intensity as a function of inner acceptance angle of the detector in a scanning transmission electron microscope. By using size-selected nanoclusters of Pd (Z = 46) and Au (Z = 79), it is shown experimentally that the exponent in the power law I ˜ Zα varies strongly between 1.2 and 1.8 as the collection angle changes from 14 to 103 mrad. The result is discussed in line with existing theoretical models. Factors, such as cluster size, structure, and orientation as well as the detector geometry, are also discussed for potential use of the work.

  14. Automated layout and phase assignment techniques for dark-field alternating PSM

    NASA Astrophysics Data System (ADS)

    Kahng, Andrew B.; Wang, Huijuan; Zelikovsky, Alexander

    1998-12-01

    We describe new, efficient algorithms for layout modification and phase assignment for dark field alternating-type phase- shifting masks in the single-exposure regime. We make the following contributions. First, we give optimal and fast algorithms to minimize the number of phase conflicts that must be removed to ensure 2-colorability of the conflict graph. These methods can potentially reduce runtime and/or improve solution quality, compared to previous approaches of Moniwa et al. and Ooi et al. Second, we suggest a new iterative 2- coloring and compaction approach that simultaneously optimizes layout and phase assignment. The approach iteratively performs the following steps: (1) compact the layout and find the conflict graph; (2) find the minimum set of edges whose deletion makes the conflict graph bipartite; and (3) add a new compaction constraint for each edge in this minimum set, such that the corresponding pair of features will no longer conflict. Third, we describe additional approaches to co- optimization of layout and phase assignment for alternating PSM. Preliminary computational experience appears promising.

  15. STEM Electron Diffraction and High Resolution Images Used in the Determination of the Crystal Structure of Au144(SR)60 Cluster

    PubMed Central

    Bahena, Daniel; Bhattarai, Nabraj; Santiago, Ulises; Tlahuice, Alfredo; Ponce, Arturo; Bach, Stephan B. H.; Yoon, Bokwon; Whetten, Robert L.; Landman, Uzi; Jose-Yacaman, Miguel

    2013-01-01

    Determination of the total structure of molecular nanocrystals is an outstanding experimental challenge that has been met, in only a few cases, by single-crystal X-ray diffraction. Described here is an alternative approach that is of most general applicability and does not require the fabrication of a single crystal. The method is based on rapid, time-resolved nanobeam electron diffraction (NBD) combined with high-angle annular dark field scanning/transmission electron microscopy (HAADF-STEM) images in a probe corrected STEM microscope, operated at reduced voltages. The results are compared with theoretical simulations of images and diffraction patterns obtained from atomistic structural models derived through first-principles density functional theory (DFT) calculations. The method is demonstrated by application to determination of the structure of the Au144(SCH2CH2Ph)60 cluster. PMID:23687562

  16. Preliminary Assessment of Tricuspid Valve Annular Velocity Parameters by Cardiac Magnetic Resonance Imaging in Adults with a Volume-Overloaded Right Ventricle: Comparison of Unrepaired Atrial Septal Defect and Repaired Tetralogy of Fallot.

    PubMed

    Ito, Seiji; McElhinney, Doff B; Adams, Robert; Bhatla, Puneet; Chung, Sohae; Axel, Leon

    2015-08-01

    The aim is to compare tricuspid valve (TV) atrioventricular junction (AVJ) annular motion parameters in unrepaired atrial septal defect (ASD) and repaired Tetralogy of Fallot (TOF) by cardiac magnetic resonance (CMR) imaging. We retrospectively reviewed CMR studies performed between November 2007 and November 2013 in patients 16-45 years of age with unrepaired ASD (with or without partial anomalous pulmonary venous return) and with repaired TOF, who had previous infundibulotomy, but have not undergone pulmonary valve replacement. Longitudinal motion of lateral TV in four-chamber view cine image was tracked through the cardiac cycle with custom software. Twenty TOF patients and 12 ASD patients were included, and values were compared with 80 controls. Right ventricular end-diastolic volume index and right ventricular end-systolic volume index were similar in the ASD and TOF groups and were significantly higher in both groups than in controls. Maximum displacement of the TV in systole, velocity at half-maximal displacement during systole, and velocity at half-maximal displacement during early diastole were all significantly lower in the TOF group than the ASD group [1.39 ± 0.47 vs. 2.21 ± 0.46 (cm, p < 0.01), 5.9 ± 2.1 vs. 10.1 ± 2.3 (cm/s, p < 0.01), and 7.7 ± 2.6 vs. 10.9 ± 3.1 (cm/s, p < 0.05)]. TOF patients have diminished early diastolic TV AVJ velocity compared to patients with an unrepaired ASD, despite similar RV volumes. This observation could suggest diastolic dysfunction or cardiac mechanics unique to the postoperative, volume-overloaded right ventricle in patients with repaired TOF.

  17. Probe and object function reconstruction in incoherent stem imaging

    SciTech Connect

    Nellist, P.D.; Pennycook, S.J.

    1996-09-01

    Using the phase-object approximation it is shown how an annular dark- field (ADF) detector in a scanning transmission electron microscope (STEM) leads to an image which can be described by an incoherent model. The point spread function is found to be simply the illuminating probe intensity. An important consequence of this is that there is no phase problem in the imaging process, which allows various image processing methods to be applied directly to the image intensity data. Using an image of a GaAs<110>, the probe intensity profile is reconstructed, confirming the existence of a 1.3 {Angstrom} probe in a 300kV STEM. It is shown that simply deconvolving this reconstructed probe from the image data does not improve its interpretability because the dominant effects of the imaging process arise simply from the restricted resolution of the microscope. However, use of the reconstructed probe in a maximum entropy reconstruction is demonstrated, which allows information beyond the resolution limit to be restored and does allow improved image interpretation.

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

    PubMed

    Brinkers, Sanneke; Dietrich, Heidelinde R C; de Groote, Frederik H; Young, Ian T; Rieger, Bernd

    2009-06-07

    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 nanoparticle undergoing constrained Brownian motion are captured. The nanoparticle is tethered to a substrate using a single double stranded DNA (dsDNA) molecule and immersed in buffer. No force is exerted on the DNA. We carried out Monte Carlo simulations of the experiment, which give insight into the micromechanics of the DNA and can be used to interpret the motion of the nanoparticle. Our simulations and experiments demonstrate that, unlike other similar experiments, the use of nanometer instead of micrometer sized particles causes particle-substrate and particle-DNA interactions to be of negligible effect on the position distribution of the particle. We also show that the persistence length of the tethering DNA can be estimated with a statistical error of 2 nm, by comparing the statistics of the projected position distribution of the nanoparticle to the Monte Carlo simulations. The persistence lengths of 45 single molecules of four different lengths of dsDNA were measured under the same environmental conditions at high salt concentration. The persistence lengths we found had a mean value of 35 nm (standard error of 2.8 nm), which compares well to previously found values using similar salt concentrations. Our method can be used to directly study the effect of the environmental conditions (e.g., buffer and temperature) on the persistence length.

  19. Direct imaging of localized surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Balci, Sinan; Karademir, Ertugrul; Kocabas, Coskun; Aydinli, Atilla

    2011-09-01

    In this Letter, we report on dark field imaging of localized surface plasmon polaritons (SPPs) in plasmonic waveguiding bands formed by plasmonic coupled cavities. We image the light scattered from SPPs in the plasmonic cavities excited by a tunable light source. Tuning the excitation wavelength, we measure the localization and dispersion of the plasmonic cavity mode. Dark field imaging has been achieved in the Kretschmann configuration using a supercontinuum white-light laser equipped with an acoustooptic tunable filter. Polarization dependent spectroscopic reflection and dark field imaging measurements are correlated and found to be in agreement with finite-difference time-domain calculations.

  20. Atomic-scale imaging of cation ordering in inverse spinel Zn2SnO4 nanowires.

    PubMed

    Bao, Lihong; Zang, Jianfeng; Wang, Guofeng; Li, Xiaodong

    2014-11-12

    By using high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) coupled with density functional theory (DFT) calculations, we demonstrate the atomic-level imaging of cation ordering in inverse spinel Zn2SnO4 nanowires. This cation ordering was identified as 1:1 ordering of Zn(2+) and Sn(4+) at the octahedral sites of the inverse spinel crystal with microscopic symmetry transition from original cubic Fd3̅m to orthorhombic Imma group. This ordering generated a 67.8% increase in the elastic modulus and 1-2 order of magnitude lower in the electric conductivity and electron mobility compared to their bulk counterpart.

  1. Simultaneous Maximum-Likelihood Reconstruction of Absorption Coefficient, Refractive Index and Dark-Field Scattering Coefficient in X-Ray Talbot-Lau Tomography

    PubMed Central

    Ritter, André; Anton, Gisela; Weber, Thomas

    2016-01-01

    A maximum-likelihood reconstruction technique for X-ray Talbot-Lau tomography is presented. This technique allows the iterative simultaneous reconstruction of discrete distributions of absorption coefficient, refractive index and a dark-field scattering coefficient. This technique avoids prior phase retrieval in the tomographic projection images and thus in principle allows reconstruction from tomographic data with less than three phase steps per projection. A numerical phantom is defined which is used to evaluate convergence of the technique with regard to photon statistics and with regard to the number of projection angles and phase steps used. It is shown that the use of a random phase sampling pattern allows the reconstruction even for the extreme case of only one single phase step per projection. The technique is successfully applied to measured tomographic data of a mouse. In future, this reconstruction technique might also be used to implement enhanced imaging models for X-ray Talbot-Lau tomography. These enhancements might be suited to correct for example beam hardening and dispersion artifacts and improve overall image quality of X-ray Talbot-Lau tomography. PMID:27695126

  2. Annular Solar Eclipse of 10 May 1994

    NASA Technical Reports Server (NTRS)

    Espenak, Fred; Anderson, Jay

    1993-01-01

    An annular eclipse of the Sun will be widely visible from the Western Hemisphere on 10 May 1994. The path of the Moon's shadow passes through Mexico, the United States of America, maritime Canada, the North Atlantic, the Azores and Morocco. Detailed predictions for this event are presented and include tables of geographic coordinates of the annular path, local circumstances for hundreds of cities, maps of the path of annular and partial eclipse, weather prospects, and the lunar limb profile.

  3. Three-dimensional imaging of dislocations in a nanoparticle at atomic resolution.

    PubMed

    Chen, Chien-Chun; Zhu, Chun; White, Edward R; Chiu, Chin-Yi; Scott, M C; Regan, B C; Marks, Laurence D; Huang, Yu; Miao, Jianwei

    2013-04-04

    Dislocations and their interactions strongly influence many material properties, ranging from the strength of metals and alloys to the efficiency of light-emitting diodes and laser diodes. Several experimental methods can be used to visualize dislocations. Transmission electron microscopy (TEM) has long been used to image dislocations in materials, and high-resolution electron microscopy can reveal dislocation core structures in high detail, particularly in annular dark-field mode. A TEM image, however, represents a two-dimensional projection of a three-dimensional (3D) object (although stereo TEM provides limited information about 3D dislocations). X-ray topography can image dislocations in three dimensions, but with reduced resolution. Using weak-beam dark-field TEM and scanning TEM, electron tomography has been used to image 3D dislocations at a resolution of about five nanometres (refs 15, 16). Atom probe tomography can offer higher-resolution 3D characterization of dislocations, but requires needle-shaped samples and can detect only about 60 per cent of the atoms in a sample. Here we report 3D imaging of dislocations in materials at atomic resolution by electron tomography. By applying 3D Fourier filtering together with equal-slope tomographic reconstruction, we observe nearly all the atoms in a multiply twinned platinum nanoparticle. We observed atomic steps at 3D twin boundaries and imaged the 3D core structure of edge and screw dislocations at atomic resolution. These dislocations and the atomic steps at the twin boundaries, which appear to be stress-relief mechanisms, are not visible in conventional two-dimensional projections. The ability to image 3D disordered structures such as dislocations at atomic resolution is expected to find applications in materials science, nanoscience, solid-state physics and chemistry.

  4. Spectroscopic imaging in electron microscopy

    SciTech Connect

    Pennycook, Stephen J; Colliex, C.

    2012-01-01

    In the scanning transmission electron microscope, multiple signals can be simultaneously collected, including the transmitted and scattered electron signals (bright field and annular dark field or Z-contrast images), along with spectroscopic signals such as inelastically scattered electrons and emitted photons. In the last few years, the successful development of aberration correctors for the electron microscope has transformed the field of electron microscopy, opening up new possibilities for correlating structure to functionality. Aberration correction not only allows for enhanced structural resolution with incident probes into the sub-angstrom range, but can also provide greater probe currents to facilitate mapping of intrinsically weak spectroscopic signals at the nanoscale or even the atomic level. In this issue of MRS Bulletin, we illustrate the power of the new generation of electron microscopes with a combination of imaging and spectroscopy. We show the mapping of elemental distributions at atomic resolution and also the mapping of electronic and optical properties at unprecedented spatial resolution, with applications ranging from graphene to plasmonic nanostructures, and oxide interfaces to biology.

  5. Free transverse vibration of a wrinkled annular thin film by using finite difference method

    NASA Astrophysics Data System (ADS)

    Wang, C. G.; Liu, Y. P.; Lan, L.; Tan, H. F.

    2016-02-01

    This paper investigates the free transverse vibration of a wrinkled annular thin film. The non-dimensional Hamilton motion equation of the wrinkled annular thin film is established, which is solved by using the finite difference method to acquire the vibration frequency and mode. The predicted vibration characteristics are verified by the experimental measurements based on the digital image correlation (DIC) technique. The results show that wrinkles have great effects on the vibration of the annular thin film. Especially for the heavily wrinkled cases, the local-global interactive mode dominates the vibration of the annular thin film. The frequency increases as the wrinkling level increases which is mainly due to the increased nonlinear geometric stiffness. The results provide favorable supports for understanding the role of nonlinear wrinkling on the vibration of thin films.

  6. Characterization of Lumbar Spine Annular Disruption in PMHS Using MRI, Cryomicrotomy and Histology Techniques.

    PubMed

    Curry, William H; Stemper, Brian D; Pryzbylo, Jason; Trueden, Justine; Wilkins, Natasha; Paskoff, Glenn R; Shender, Barry S

    2015-01-01

    Internal intervertebral disc disruption is involved in the onset of a wide range of spinal dysfunction, ultimately affecting not only the disc itself but the surrounding osseous and neural structures as well. The ability of disc to withstand and effectively distribute axial load is dependent upon whether peripherally located annular fibers provide the support necessary to contain and corral the pressure sensitive nucleus. Any alteration in the structures immediate to the nucleus jeopardize this ability. While annular tears and fissures have been thoroughly investigated, one form of internal disc disruption is less well-understood. A network of elastin cross-bridges provides resistance to delamination of the collagenous sheets that comprise the annulus. The current investigation utilized a Nitrogen gas-induced pressure mechanism to disrupt elastin cross links that exist between annular lamellae. Twenty five cadaveric lumbar spine motion segments (mean age: 52±12 yr.) were subjected to the annular disruption protocol. Damage to the annulus was assessed using MRI, cryomicrotome and histological staining procedures. MRI images were compared to cryomicrotome images to determine the ability of standard clinical MRI scans to determine annular damage. In many cases MRI was moderately revealing in terms of damage. Future studies will quantify biomechanical consequences of these low level annular disruptions relative to segmental stability.

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

    NASA Astrophysics Data System (ADS)

    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.

  8. Atomic imaging using secondary electrons in a scanning transmission electron microscope: experimental observations and possible mechanisms.

    PubMed

    Inada, H; Su, D; Egerton, R F; Konno, M; Wu, L; Ciston, J; Wall, J; Zhu, Y

    2011-06-01

    We report detailed investigation of high-resolution imaging using secondary electrons (SE) with a sub-nanometer probe in an aberration-corrected transmission electron microscope, Hitachi HD2700C. This instrument also allows us to acquire the corresponding annular dark-field (ADF) images both simultaneously and separately. We demonstrate that atomic SE imaging is achievable for a wide range of elements, from uranium to carbon. Using the ADF images as a reference, we studied the SE image intensity and contrast as functions of applied bias, atomic number, crystal tilt, and thickness to shed light on the origin of the unexpected ultrahigh resolution in SE imaging. We have also demonstrated that the SE signal is sensitive to the terminating species at a crystal surface. A possible mechanism for atomic-scale SE imaging is proposed. The ability to image both the surface and bulk of a sample at atomic-scale is unprecedented, and can have important applications in the field of electron microscopy and materials characterization.

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

    PubMed Central

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

    2016-01-01

    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. PMID:27619347

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

    NASA Astrophysics Data System (ADS)

    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.

  11. Unexpected bismuth concentration profiles in metal-organic vapor phase epitaxy-grown Ga(As{sub 1−x}Bi{sub x})/GaAs superlattices revealed by Z-contrast scanning transmission electron microscopy imaging

    SciTech Connect

    Wood, A. W.; Babcock, S. E.; Guan, Y.; Forghani, K.; Anand, A.; Kuech, T. F.

    2015-03-01

    A set of GaAs{sub 1−x}Bi{sub x}/GaAs multilayer quantum-well structures was deposited by metal-organic vapor phase epitaxy at 390 °C and 420 °C. The precursor fluxes were introduced with the intent of growing discrete and compositionally uniform GaAs{sub 1−x}Bi{sub x} well and GaAs barrier layers in the epitaxial films. High-resolution high-angle annular-dark-field (or “Z-contrast”) scanning transmission electron microscopy imaging revealed concentration profiles that were periodic in the growth direction, but far more complicated in shape than the intended square wave. The observed composition profiles could explain various reports of physical properties measurements that suggest compositional inhomogeneity in GaAs{sub 1−x}Bi{sub x} alloys as they currently are grown.

  12. Illumination pupil optimization in 0.33NA EUVL by intensity balancing for semi-iso dark field two-bar M1 building blocks

    NASA Astrophysics Data System (ADS)

    Last, T.; de Winter, L.; van Adrichem, P.; Finders, J.

    2016-10-01

    We will shed light on the optimization of lithographic metrics for the semi-isolated dark field two-bar logic building block. Under standard D90Y illumination this building block suffers from large mask 3D induced relative focus dependent CD asymmetries. Such behavior limits its overlapping process window and gives rise to untenable full wafer CDU and intra-field pattern shifts. We have found that besides a Ta absorber thickness reduction an illumination pupil optimization is necessary to fully remove these CD asymmetries. The pupil optimization is achieved by relating the aerial image decomposition (here: symmetrization and balancing of intensities across the diffracted orders) with lithographic metrics per pupil plane location. The resulting pupil allows us (i) to lift the focus-dependent CD asymmetries and (ii) to co-optimize a number of lithographic metrics such as overlapping process window, contrast, non-telecentricity and pattern shift. The importance of subsidiary conditions (e.g. symmetry of the pupil, required DOF) will be discussed.

  13. Means of manufacturing annular arrays

    DOEpatents

    Day, R.A.

    1985-10-10

    A method is described for manufacturing an annular acoustic transducer array from a plate of transducer material, which enables production of precision aligned arrays at low cost. The circular plate is sawed along at least two lines that are radial to the axis of the plate. At steps along each radial cut, the plate is rotated first in one direction and then in an opposite direction by a predetermined angle such as slightly less than 90/sup 0/. The cuts result in the forming of several largely ring-shaped lands, each largely ring-shaped land being joined to the other rings of different radii by thin portions of the plate, and each ring being cut into segments. The bridges that join different rings hold the transducer together until it can be mounted on a lens.

  14. Higher modes in the coupling cells of coaxial and annular-ring coupled linac structures

    SciTech Connect

    Hoffswell, R.A.; Laszewski, R.M.

    1983-08-01

    Dipole- and quadrupole-like modes in the coupling cells of coaxial and annular-ring coupled structures have been examined up to a frequency of 4 GHz. The quadrupole mode frequencies appear to lie high enough above the frequency of the accelerating mode to make coupling between the two unlikely. In the annular-ring case, however, a dipole mode was found very near the accelerating mode frequency. Evidence is presented which suggests that some power may couple between these two modes in a real cavity.

  15. Method and apparatus for continuous annular electrochromatography

    DOEpatents

    Scott, Charles D.

    1987-01-01

    Separation of complex mixtures and solutions can be carried out using a method and apparatus for continuous annular electrochromatography. Solutes are diverted radially by an imposed electrical field as they move downward in a rotating chromatographic column.

  16. Multiple Granuloma Annulare in a 2-year-old Child

    PubMed Central

    Siddalingappa, Karjigi; Murthy, Sambasiviah Chidambara; Herakal, Kallappa; Kusuma, Marganahalli Ramachandra

    2015-01-01

    Granuloma annulare is a benign, self-limiting, inflammatory and granulomatous disease of unknown etiology occurring in both adults and children. An 18-month-old male child had multiple progressive annular plaques over the lower extremities. Clinical and histopathological features were consistent with granuloma annulare. Localized granuloma annulare is the most common form in children. We report a young child with multiple, progressive granuloma annulare over the lower extremities. PMID:26677301

  17. Annular gel reactor for chemical pattern formation

    DOEpatents

    Nosticzius, Zoltan; Horsthemke, Werner; McCormick, William D.; Swinney, Harry L.; Tam, Wing Y.

    1990-01-01

    The present invention is directed to an annular gel reactor suitable for the production and observation of spatiotemporal patterns created during a chemical reaction. The apparatus comprises a vessel having at least a first and second chamber separated one from the other by an annular polymer gel layer (or other fine porous medium) which is inert to the materials to be reacted but capable of allowing diffusion of the chemicals into it.

  18. Annular-Cross-Section CFE Chamber

    NASA Technical Reports Server (NTRS)

    Sharnez, Rizwan; Sammons, David W.

    1994-01-01

    Proposed continuous-flow-electrophoresis (CFE) chamber of annular cross section offers advantages over conventional CFE chamber, and wedge-cross-section chamber described in "Increasing Sensitivity in Continuous-Flow Electrophoresis" (MFS-26176). In comparison with wedge-shaped chamber, chamber of annular cross section virtually eliminates such wall effects as electro-osmosis and transverse gradients of velocity. Sensitivity enhanced by incorporating gradient maker and radial (collateral) flow.

  19. Direct visualization of lithium via annular bright field scanning transmission electron microscopy: a review.

    PubMed

    Findlay, Scott David; Huang, Rong; Ishikawa, Ryo; Shibata, Naoya; Ikuhara, Yuichi

    2017-02-08

    Annular bright field (ABF) scanning transmission electron microscopy has proven able to directly image lithium columns within crystalline environments, offering much insight into the structure and properties of lithium-ion battery materials. We summarize the image formation mechanisms underpinning ABF imaging, review the experimental application of this technique to imaging lithium in materials and overview the conditions that help maximize the visibility of lithium columns.

  20. Real-time optical detection of single human and bacterial viruses based on dark-field interferometry.

    PubMed

    Mitra, Anirban; Ignatovich, Filipp; Novotny, Lukas

    2012-01-15

    The rapid and sensitive detection and characterization of human viruses and bacteriophage is extremely important in a variety of fields, such as medical diagnostics, immunology and vaccine research, and environmental contamination and quality control. We introduce an optical detection scheme for real-time and label-free detection of human viruses and bacteriophage as small as ~24 nm in radius. Combining the advantages of heterodyne interferometry and dark-field microscopy, this label-free method enables us to detect and characterize various biological nanoparticles with unsurpassed sensitivity and selectivity. We demonstrate the high sensitivity and precision of the method by analyzing a mixture containing HIV virus and bacteriophage. The method also resolves the distribution of small nano-impurities (~20-30 nm) in clinically relevant virus samples.

  1. Design and application of three-zone annular filters

    NASA Astrophysics Data System (ADS)

    Liu, Ximin; Liu, Liren; Liu, De'an; Bai, Lihua

    2006-10-01

    We design three-zone annular filters to be applied to optical storage system. The designed filters extend the depth of focus and realize transverse superresolution simultaneously, which will improve the performance of optical storage system greatly. And we propose two feasible schemes to improve imaging resolution of three-dimensional imaging system. One scheme depends on a complex filter formed by cascading of a three-zone phase filter and a three-zone amplitude filter. The complex filter converge the optimized transverse superresolution and the optimized axial superresolution of two different filters onto a single filter. It can improve the three-dimensional imaging performances greatly. Another scheme depends on a single three-zone complex filter. We propose a three-zone complex filter with phase shift 0.8[pi], which presents bigger design margin, better imaging quality and stronger three-dimensional superresolution capability.

  2. Beamforming using spatial matched filtering with annular arrays (L).

    PubMed

    Kim, Kang-Sik; Liu, Jie; Insana, Michael F

    2007-04-01

    A linear array beamforming method for ultrasonic B-mode imaging using spatial matched filtering (SMF) and a rectangular aperture geometry was recently proposed Kim et al., [J. Acoust. Soc. Am. 120, 852-861 (2006)]. This letter extends those results to include circularly symmetric apertures. SMF applied to annular arrays can improve the lateral resolution and echo signal-to-noise ratio as compared with conventional dynamic-receive delay-sum beamforming. At high frequencies, where delay and sum beamforming is problematic, SMF showed greatly improved target contrast over an extended field of view.

  3. Panoramic optical annular staring inspection system for evaluating the inner surface of a pipe

    NASA Astrophysics Data System (ADS)

    Zhao, Liefeng; Feng, Huajun; Bai, Jian; Jin, Hao

    2008-01-01

    There should be flaws and defects on the inner surface during the producing period of a pipe, as well as contaminations and corrosions during the using period of it. A corresponding panoramic optical annular staring inspection system has been developed. It requires no rotating mechanism to exam the whole circumference of a cross section of the inner pipe surface at once, which results high speed inspection. There are two main subsystems in this inspection system, the panoramic optical annular staring imaging subsystem and driving robot subsystem. The Flat Cylinder Perspective (FCP) is the principle to image a panoramic annular view to a flat imagery, i.e. a cylinder of vision imaged is flat. Our imaging subsystem includes a panoramic annular lens (PAL), which is critical and used to implement the FCP, a series of image rotation lenses, a charge-coupled device (CCD) camera, and an illuminating light-emitting diode (LED) ring. The CCD camera sending the signal to a personal computer (PC) via VGA signal results a real time inspection. The driving robot subsystem is a fine designed complicated mechanism including a subassembly of stepper motor. It can drive the inspection system forward and backward continuously in the pipe along the axial direction. The experimental system reported in this paper has the following specifications: average detection resolution of 0.5 mm at the circumference direction and 1.0 mm at the axial direction of a pipe, and inspection speed of 15 mm/s.

  4. Duodenal Atresia In Utero in Association With Down's Syndrome and Annular Pancreas

    PubMed Central

    Clark, John F.J.; Hales, Earle; Ma, Peter; Rosser, Samuel B.

    1984-01-01

    A 28-weeks' gestational trisomic-21 male, with duodenal atresia due to annular pancreas, is presented. The atresia was diagnosed in utero by sonographic techniques. A review of the pertinent literature and discussion of management are presented. ImagesFigure 1Figure 2Figure 3Figure 4 PMID:6231382

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

    NASA Astrophysics Data System (ADS)

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

    2012-12-01

    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.

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

    NASA Astrophysics Data System (ADS)

    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.

  7. What causes Mars' annular polar vortices?

    NASA Astrophysics Data System (ADS)

    Toigo, A. D.; Waugh, D. W.; Guzewich, S. D.

    2017-01-01

    A distinctive feature of the Martian atmosphere is that the winter polar vortices exhibit annuli of high potential vorticity (PV) with a local minimum near the pole. These annuli are seen in observations, reanalyses, and free-running general circulation model simulations of Mars, but are not generally a feature of Earth's polar vortices, where there is a monotonic increase in magnitude of PV with latitude. The creation and maintenance of the annular polar vortices on Mars are not well understood. Here we use simulations with a Martian general circulation model to the show that annular vortices are related to another distinctive, and possibly unique in the solar system, feature of the Martian atmosphere: the condensation of the predominant atmospheric gas species (CO2) in polar winter regions. The latent heat associated with CO2 condensation leads to destruction of PV in the polar lower atmosphere, inducing the formation of an annular PV structure.

  8. Annular feed air breathing fuel cell stack

    DOEpatents

    Wilson, Mahlon S.

    1996-01-01

    A stack of polymer electrolyte fuel cells is formed from a plurality of unit cells where each unit cell includes fuel cell components defining a periphery and distributed along a common axis, where the fuel cell components include a polymer electrolyte membrane, an anode and a cathode contacting opposite sides of the membrane, and fuel and oxygen flow fields contacting the anode and the cathode, respectively, wherein the components define an annular region therethrough along the axis. A fuel distribution manifold within the annular region is connected to deliver fuel to the fuel flow field in each of the unit cells. In a particular embodiment, a single bolt through the annular region clamps the unit cells together. In another embodiment, separator plates between individual unit cells have an extended radial dimension to function as cooling fins for maintaining the operating temperature of the fuel cell stack.

  9. Direct Imaging of Carboxymethyl Cellulose-mediated Aggregation of Lactic Acid Bacteria Using Dark-field Microscopy.

    PubMed

    Nakao, Hidenobu; Saito, Katsuichi; Tomita, Satoru; Magariyama, Yukio; Kaizuka, Yoshihisa; Takeda, Yoshihiko

    2016-01-01

    The ecological functions of lactic acid bacteria (LAB) have been utilized in human life for food processing and probiotic therapy. Understanding the interaction mechanisms between LAB and food ingredients may help to clarify the fermentation process and physiological functions of LAB in the production of fermented foods made from plant materials and dairy products. However, the interaction mechanisms have yet to be fully clarified. Although laser diffraction was used for measuring the size changes of aggregates caused by the interaction between LAB and food ingredients, aggregate sizes could not be determined because of the precipitation of aggregates and its disruption from stirring. Therefore, a microscopy-based method for directly visualizing their interactions is required. We directly observed aggregation processes of LAB cells mediated by water-soluble polysaccharides, carboxymethyl cellulose (CMC), by dark-filed microscopy (DFM). DFM could visualize CMC-mediated cell aggregation with high contrast in real time, and revealed that the aggregates were formed by repeated collisions of LAB cells in a suspension. This suggests that our method can be used as a useful assay to directly visualize grain formation caused by interactions between LAB cells and various polysaccharides in food ingredients.

  10. Aberration-corrected STEM/TEM imaging at 15kV.

    PubMed

    Sasaki, Takeo; Sawada, Hidetaka; Hosokawa, Fumio; Sato, Yuta; Suenaga, Kazu

    2014-10-01

    The performance of aberration-corrected (scanning) transmission electron microscopy (S/TEM) at an accelerating voltage of 15kV was evaluated in a low-voltage microscope equipped with a cold-field emission gun and a higher-order aberration corrector. Aberrations up to the fifth order were corrected by the aberration measurement and auto-correction system using the diffractogram tableau method in TEM and Ronchigram analysis in STEM. TEM observation of nanometer-sized particles demonstrated that aberrations up to an angle of 50mrad were compensated. A TEM image of Si[110] exhibited lattice fringes with a spacing of 0.192nm, and the power spectrum of the image showed spots corresponding to distances of 0.111nm. An annular dark-field STEM image of Si[110] showed lattice fringes of (111) and (22¯0) planes corresponding to lattice distances of 0.314nm and 0.192nm, respectively. At an accelerating voltage of 15kV, the developed low-voltage microscope achieved atomic-resolution imaging with a small chromatic aberration and a large uniform phase.

  11. Advanced electron crystallography through model-based imaging

    PubMed Central

    Van Aert, Sandra; De Backer, Annick; Martinez, Gerardo T.; den Dekker, Arnold J.; Van Dyck, Dirk; Bals, Sara; Van Tendeloo, Gustaaf

    2016-01-01

    The increasing need for precise determination of the atomic arrangement of non-periodic structures in materials design and the control of nanostructures explains the growing interest in quantitative transmission electron microscopy. The aim is to extract precise and accurate numbers for unknown structure parameters including atomic positions, chemical concentrations and atomic numbers. For this purpose, statistical parameter estimation theory has been shown to provide reliable results. In this theory, observations are considered purely as data planes, from which structure parameters have to be determined using a parametric model describing the images. As such, the positions of atom columns can be measured with a precision of the order of a few picometres, even though the resolution of the electron microscope is still one or two orders of magnitude larger. Moreover, small differences in average atomic number, which cannot be distinguished visually, can be quantified using high-angle annular dark-field scanning transmission electron microscopy images. In addition, this theory allows one to measure compositional changes at interfaces, to count atoms with single-atom sensitivity, and to reconstruct atomic structures in three dimensions. This feature article brings the reader up to date, summarizing the underlying theory and highlighting some of the recent applications of quantitative model-based transmisson electron microscopy. PMID:26870383

  12. Geometry optimization of linear and annular plasma synthetic jet actuators

    NASA Astrophysics Data System (ADS)

    Neretti, G.; Seri, P.; Taglioli, M.; Shaw, A.; Iza, F.; Borghi, C. A.

    2017-01-01

    The electrohydrodynamic (EHD) interaction induced in atmospheric air pressure by a surface dielectric barrier discharge (DBD) actuator has been experimentally investigated. Plasma synthetic jet actuators (PSJAs) are DBD actuators able to induce an air stream perpendicular to the actuator surface. These devices can be used in the field of aerodynamics to prevent or induce flow separation, modify the laminar to turbulent transition inside the boundary layer, and stabilize or mix air flows. They can also be used to enhance indirect plasma treatment effects, increasing the reactive species delivery rate onto surfaces and liquids. This can play a major role in plasma processing and chemical kinetics modelling, where often only diffusive mechanisms are considered. This paper reports on the importance that different electrode geometries can have on the performance of different PSJAs. A series of DBD aerodynamic actuators designed to produce perpendicular jets has been fabricated on two-layer printed circuit boards (PCBs). Both linear and annular geometries were considered, testing different upper electrode distances in the linear case and different diameters in the annular one. An AC voltage supplied at a peak of 11.5 kV and a frequency of 5 kHz was used. Lower electrodes were connected to the ground and buried in epoxy resin to avoid undesired plasma generation on the lower actuator surface. Voltage and current measurements were carried out to evaluate the active power delivered to the discharges. Schlieren imaging allowed the induced jets to be visualized and gave an estimate of their evolution and geometry. Pitot tube measurements were performed to obtain the velocity profiles of the PSJAs and to estimate the mechanical power delivered to the fluid. The optimal values of the inter-electrode distance and diameter were found in order to maximize jet velocity, mechanical power or efficiency. Annular geometries were found to achieve the best performance.

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

    PubMed Central

    Chandel, Shubham; Soni, Jalpa; Ray, Subir kumar; Das, Anwesh; Ghosh, Anirudha; Raj, Satyabrata; Ghosh, Nirmalya

    2016-01-01

    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 4 × 4 spectroscopic scattering Mueller matrices from single nanoparticle/nanostructures are overcome by integrating an efficient Mueller matrix measurement scheme and a robust eigenvalue calibration method with a dark-field microscopic spectroscopy arrangement. Feasibility of quantitative Mueller matrix polarimetry and its potential utility is illustrated on a simple plasmonic system, that of gold nanorods. The demonstrated ability to record full polarization information over a broad wavelength range and to quantify the intrinsic plasmon polarimetry characteristics via Mueller matrix inverse analysis should lead to a novel route towards quantitative understanding, analysis/interpretation of a number of intricate plasmonic effects and may also prove useful towards development of polarization-controlled novel sensing schemes. PMID:27212687

  14. Annular lichenoid syphilis: A rare entity.

    PubMed

    Khurana, Ananta; Singal, Archana; Gupta, Seema

    2014-01-01

    Syphilis is a disease known for centuries, but still continues to be a diagnostic challenge as the myriad manifestations of secondary syphilis can mimic a lot many dermatological disorders. Lichenoid syphilis is an uncommon entity, reported only occasionally in the penicillin era. We present the case of a 32-year-old woman presenting with localized annular lichenoid lesions on the neck.

  15. Annular Pressure Seals and Hydrostatic Bearings

    DTIC Science & Technology

    2006-11-01

    affecting the rotordynamics of liquid turbopumps, in particular those handling large density fluids. Highlights on the bulk-flow analysis of annular seals... rotordynamic stability. Hydrostatic bearings rely on external fluid pressurization to generate load support and large centering stiffnesses, even in...SEALS IN PUMP APPLICATIONS Seal rotordynamic characteristic have a primary influence on the stability response of high-performance turbomachinery [1

  16. Annular lichenoid syphilis: A rare entity

    PubMed Central

    Khurana, Ananta; Singal, Archana; Gupta, Seema

    2014-01-01

    Syphilis is a disease known for centuries, but still continues to be a diagnostic challenge as the myriad manifestations of secondary syphilis can mimic a lot many dermatological disorders. Lichenoid syphilis is an uncommon entity, reported only occasionally in the penicillin era. We present the case of a 32-year-old woman presenting with localized annular lichenoid lesions on the neck. PMID:26396452

  17. Swirling Annular Flow Experiments with Application to Plasma Torches

    NASA Astrophysics Data System (ADS)

    Fisher, L. E.; Settles, G. S.; Miller, J. D.

    2001-11-01

    Swirling flows have many applications such as combustors and cyclone separators. Here, a turbulent swirling annular cold-flow experiment is conducted in order to gain insight into conditions within a plasma cutting torch. Compressed air is forced through six circumferentially-spaced holes that impart tangential velocity to the flow at the annulus inlet. The flow subsequently traverses an annulus of L/D1 =1.8 before exiting through a sonic nozzle. The annulus (created by a cylindrical cathode in the center of the actual plasma torch) is viewable through an outer plexiglass cylinder in our 11:1 scaled-up cold-flow apparatus. Surface oil-flow visualization and laser sheet imaging are employed to investigate the annular flowfield at a Reynolds number of about 1000 based on gap width D2-D1. Results of these experiments, leading to a physical model of the flowfield, are shown. These results are helpful in understanding and improving the fluid-dynamic behavior of actual plasma torches, widely used to cut sheet metal in manufacturing. Supported by Hypertherm Inc.

  18. The Growth of Instabilities in Annular Liquid Sheets

    SciTech Connect

    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.

  19. Effects of Gravity on Bubble Formation in an Annular Jet

    NASA Technical Reports Server (NTRS)

    Koepp, R. A.; Parthasarathy, R. N.; Gollahalli, S. R.

    2004-01-01

    The effects of gravity on the bubble formation in an annular jet were studied. The experiments were conducted in the 2.2-second drop tower at the NASA Glenn Research Center. Terrestrial gravity experiments were conducted at the Fluid Dynamics Research Laboratory at the University of Oklahoma. Stainless steel tubing with inner diameters of 1/8" (gas inner annulus) and 5/16" (liquid outer annulus) served as the injector. A rectangular test section, 6" x 6" x 14" tall, made out of half-inch thick Lexan was used. Images of the annular jet were acquired using a high-speed camera. The effects of gravity and varying liquid and gas flow rates on bubble size, wavelength, and breakup length were documented. In general, the bubble diameter was found to be larger in terrestrial gravity than in microgravity for varying Weber numbers (0.05 - 0.16 and 5 - 11) and liquid flow rates (1.5 ft/s - 3.0 ft/s). The wavelength was found to be larger in terrestrial gravity than in microgravity, but remained constant for varying Weber numbers. For low Weber numbers (0.05 - 0.16), the breakup length in microgravity was significantly higher than in terrestrial gravity. Comparison with linear stability analysis showed estimated bubble sizes within 9% of experimental bubble sizes. Bubble size compared to other terrestrial gravity experiments with same flow conditions showed distinct differences in bubble size, which displayed the importance of injector geometry on bubble formation.

  20. Management of Periocular Granuloma Annulare Using Topical Dapsone

    PubMed Central

    Patel, Mayha; Shitabata, Paul; Horowitz, David

    2015-01-01

    Granuloma annulare is a disease characterized by granulomatous inflammation of the dermis. Localized granuloma annulare may resolve spontaneously, while generalized granuloma annulare may persist for decades. The authors present the case of a 41-year-old Hispanic man with a two-week history of periocular granuloma annulare. Due to previously reported success in the use of systemic dapsone for the treatment of granuloma annulare, and the periocular proximity of the patient’s lesion, topical dapsone was used for treatment. Various additional therapies for the management of granuloma annulare have been reported, such as topical and systemic steroids, isotretinoin, pentoxifylline, cyclosporine, Interferon gamma, potassium iodide, nicotinamide, niacinamide, salicylic acid, fumaric acid ester, etanercept, infliximab, and hydroxychloroquine. Additional clinical trials are necessary to further evaluate the effectiveness of topical dapsone in the management of granuloma annulare. PMID:26203321

  1. StatSTEM: An efficient approach for accurate and precise model-based quantification of atomic resolution electron microscopy images.

    PubMed

    De Backer, A; van den Bos, K H W; Van den Broek, W; Sijbers, J; Van Aert, S

    2016-12-01

    An efficient model-based estimation algorithm is introduced to quantify the atomic column positions and intensities from atomic resolution (scanning) transmission electron microscopy ((S)TEM) images. This algorithm uses the least squares estimator on image segments containing individual columns fully accounting for overlap between neighbouring columns, enabling the analysis of a large field of view. For this algorithm, the accuracy and precision with which measurements for the atomic column positions and scattering cross-sections from annular dark field (ADF) STEM images can be estimated, has been investigated. The highest attainable precision is reached even for low dose images. Furthermore, the advantages of the model-based approach taking into account overlap between neighbouring columns are highlighted. This is done for the estimation of the distance between two neighbouring columns as a function of their distance and for the estimation of the scattering cross-section which is compared to the integrated intensity from a Voronoi cell. To provide end-users this well-established quantification method, a user friendly program, StatSTEM, is developed which is freely available under a GNU public license.

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

    SciTech Connect

    Wang, Y. Y.; Cooper, D.; Bernier, N.; Rouviere, J.; Murray, C. E.; Bruley, J.

    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.

  3. Image simulation for biological microscopy: microlith

    PubMed Central

    Mehta, Shalin B.; Oldenbourg, Rudolf

    2014-01-01

    Image simulation remains under-exploited for the most widely used biological phase microscopy methods, because of difficulties in simulating partially coherent illumination. We describe an open-source toolbox, microlith (https://code.google.com/p/microlith), which accurately predicts three-dimensional images of a thin specimen observed with any partially coherent imaging system, as well as images of coherently illuminated and self-luminous incoherent specimens. Its accuracy is demonstrated by comparing simulated and experimental bright-field and dark-field images of well-characterized amplitude and phase targets, respectively. The comparison provides new insights about the sensitivity of the dark-field microscope to mass distributions in isolated or periodic specimens at the length-scale of 10nm. Based on predictions using microlith, we propose a novel approach for detecting nanoscale structural changes in a beating axoneme using a dark-field microscope. PMID:24940543

  4. Development of an Advanced Annular Combustor

    NASA Technical Reports Server (NTRS)

    Rusnak, J. P.; Shadowen, J. H.

    1969-01-01

    The objective of the effort described in this report was to determine the structural durability of a full-scale advanced annular turbojet combustor using ASTM A-1 type fuel and operating at conditions typical of advanced supersonic aircraft. A full-scale annular combustor of the ram-induction type was fabricated and subjected to a 325-hour cyclic endurance test at conditions representative of operation in a Mach 3.0 aircraft. The combustor exhibited extensive cracking and scoop burning at the end of the test program. But these defects had no appreciable effect on combustor performance, as performance remained at a high level throughout the endurance program. Most performance goals were achieved with pressure loss values near 6% and 8%, and temperature rise variation ratio (deltaTVR) values near 1.25 and l.22 at takeoff and cruise conditions, respectively. Combustion efficiencies approached l004 and the exit radial temperature profiles were approximately as desired.

  5. LDV Measurements in an Annular Combustor Model

    NASA Technical Reports Server (NTRS)

    Barron, Dean A.

    1996-01-01

    This thesis covers the design and setup of a laser doppler velocimeter (LDV) system used to take velocity measurements in an annular combustor model. The annular combustor model is of contemporary design using 60 degree flat vane swirlers, producing a strong recirculation zone. Detailed measurements are taken of the swirler inlet air flow and of the downstream enclosed swirling flow. The laser system used is a two color, two component system set up in forward scatter. Detailed are some of the special considerations needed for LDV use in the confined turbulent flow of the combustor model. LDV measurements in a single swirler rig indicated that the flow changes radically in the first duct height. After this, a flow profile is set up and remains constant in shape. The magnitude of the velocities gradually decays due to viscous damping.

  6. Continuous separation of proteins by annular chromatography

    SciTech Connect

    Bloomingburg, G.F.; Bauer, J.S.; Carta, G. ); Byers, C.H. )

    1991-05-01

    In this paper, the separation of protein mixtures by continuous annular chromatography (CAC) is studied in a preparative-scale apparatus. S-Sepharose, a strong-acid porous cation-exchange resin is used as the separation medium, and mixtures of albumin, hemoglobin and cytochrome c are used as model separation system. Equilibrium and mass-transfer parameters are developed for this system on the basis of fixed-bed chromatograph experiments. A mathematical model is then successfully used in conjunction with these parameters to simulate the performance of the CAC separations. The continuous separation performance of the annular apparatus is found to be essentially the same as the batchwise performance of an equivalent conventional chromatograph, making the unit attractive for preparative and process-scale applications where continuous throughput is desirable.

  7. Annular and Total Solar Eclipses of 2003

    NASA Technical Reports Server (NTRS)

    Espenak, Fred; Anderson, Jay

    2002-01-01

    On Saturday, 2003 May 31, an annular eclipse of the Sun will be visible from a broad corridor that traverses the North Atlantic. The path of the Moon's antumbral shadow begins in northern Scotland, crosses Iceland and central Greenland, and ends at sunrise in Baffin Bay (Canada). A partial eclipse will be seen within the much broader path of the Moon's penumbral shadow, which includes most of Europe, the Middle East, central and northern Asia, and northwestern North America. The trajectory of the Moon's shadow is quite unusual during this event. The shadow axis passes to the far north where it barely grazes Earth's surface. In fact, the northern edge of the antumbra actually misses Earth so that one path limit is defined by the day/night terminator rather than by the shadow's upper edge. As a result, the track of annularity has a peculiar "D" shape that is nearly 1200 kilometers wide. Since the eclipse occurs just three weeks prior to the northern summer solstice, Earth's northern axis is pointed sunwards by 22.8 deg. As seen from the Sun, the antumbral shadow actually passes between the North Pole and the terminator. As a consequence of this extraordinary geometry, the path of annularity runs from east to west rather than the more typical west to east. The event transpires near the Moon's ascending node in Taurus five degrees north of Aldebaran. Since apogee occurs three days earlier (May 28 at 13 UT), the Moon's apparent diameter (29.6 arc-minutes) is still too small to completely cover the Sun (31.6 arc-minutes) resulting in an annular eclipse.

  8. The Annular Suspension and Pointing System /ASPS/

    NASA Technical Reports Server (NTRS)

    Anderson, W. W.; Woolley, C. T.

    1978-01-01

    The Annular Suspension and Pointing System (ASPS) may be attached to a carrier vehicle for orientation, mechanical isolation, and fine pointing purposes applicable to space experiments. It has subassemblies for both coarse and vernier pointing. A fourteen-degree-of-freedom simulation of the ASPS mounted on a Space Shuttle has yielded initial performance data. The simulation describes: the magnetic actuators, payload sensors, coarse gimbal assemblies, control algorithms, rigid body dynamic models of the payload and Shuttle, and a control system firing model.

  9. Annular flow film characteristics in variable gravity.

    PubMed

    MacGillivray, Ryan M; Gabriel, Kamiel S

    2002-10-01

    Annular flow is a frequently occurring flow regime in many industrial applications. The need for a better understanding of this flow regime is driven by the desire to improve the design of many terrestrial and space systems. Annular two-phase flow occurs in the mining and transportation of oil and natural gas, petrochemical processes, and boilers and condensers in heating and refrigeration systems. The flow regime is also anticipated during the refueling of space vehicles, and thermal management systems for space use. Annular flow is mainly inertia driven with little effect of buoyancy. However, the study of this flow regime is still desirable in a microgravity environment. The influence of gravity can create an unstable, chaotic film. The absence of gravity, therefore, allows for a more stable and axisymmetric film. Such conditions allow for the film characteristics to be easily studied at low gas flow rates. Previous studies conducted by the Microgravity Research Group dealt with varying the gas or liquid mass fluxes at a reduced gravitational acceleration.(1,2) The study described here continues this work by examining the effect of changing the gravitational acceleration (hypergravity) on the film characteristics. In particular, the film thickness and the associated pressure drops are examined. The film thickness was measured using a pair of two-wire conductance probes. Experimental data was collected over a range of annular flow set points by changing the liquid and gas mass flow rates, the liquid-to-gas density ratio and the gravitational acceleration. The liquid-to-gas density ratio was varied by collecting data with helium-water and air-water at the same flow rates. The gravitational effect was examined by collecting data during the microgravity and pull-up (hypergravity) portions of the parabolic flights.

  10. Annular feed air breathing fuel cell stack

    DOEpatents

    Wilson, Mahlon S.; Neutzler, Jay K.

    1997-01-01

    A stack of polymer electrolyte fuel cells is formed from a plurality of unit cells where each unit cell includes fuel cell components defining a periphery and distributed along a common axis, where the fuel cell components include a polymer electrolyte membrane, an anode and a cathode contacting opposite sides of the membrane, and fuel and oxygen flow fields contacting the anode and the cathode, respectively, wherein the components define an annular region therethrough along the axis. A fuel distribution manifold within the annular region is connected to deliver fuel to the fuel flow field in each of the unit cells. The fuel distribution manifold is formed from a hydrophilic-like material to redistribute water produced by fuel and oxygen reacting at the cathode. In a particular embodiment, a single bolt through the annular region clamps the unit cells together. In another embodiment, separator plates between individual unit cells have an extended radial dimension to function as cooling fins for maintaining the operating temperature of the fuel cell stack.

  11. Stability of Three-Layered Annular Plate with Composite Facings

    NASA Astrophysics Data System (ADS)

    Pawlus, D.

    2017-02-01

    Paper presents the behaviour of three-layered annular plates subjected to loads acting in plate plane. Plates are composed of laminated fibre-reinforced composite facings and foam core. The static and dynamic parameters of plate critical state were evaluated. The sensitivity of composite structure of plate to the acting of quickly increasing in time loads is shown. The problem has been solved numerically using the finite element method. Results have been compared with ones obtained for plate models with isotropic layers. These plate models have also been calculated solving formulated task analytically and numerically by means of the finite difference method. Solutions to the problem concern the axisymmetrical and asymmetrical plate buckling modes. Numerous presented tables and figures create the image of the stability behaviour of examined composite plates.

  12. Stability of Three-Layered Annular Plate with Composite Facings

    NASA Astrophysics Data System (ADS)

    Pawlus, D.

    2016-10-01

    Paper presents the behaviour of three-layered annular plates subjected to loads acting in plate plane. Plates are composed of laminated fibre-reinforced composite facings and foam core. The static and dynamic parameters of plate critical state were evaluated. The sensitivity of composite structure of plate to the acting of quickly increasing in time loads is shown. The problem has been solved numerically using the finite element method. Results have been compared with ones obtained for plate models with isotropic layers. These plate models have also been calculated solving formulated task analytically and numerically by means of the finite difference method. Solutions to the problem concern the axisymmetrical and asymmetrical plate buckling modes. Numerous presented tables and figures create the image of the stability behaviour of examined composite plates.

  13. TEM Lattice Imaging of the Nanostructure of Early-Growth Sputter- Deposited MoS2 Solid Lubricant Films

    DTIC Science & Technology

    1990-09-30

    REFERENCES ....................................................... 45 3 FIGURES 1. The MoS2 crystal structure ................................... 8...contains anisotropic islands ........... 16 4. Diffraction pattern of an HT MoS2 film ....................... 17 5. Diffraction pattern of an AT MoS2 film...18 6. (A) Bright-field (BF) image of an HT MoS2 film, (B) a corresponding (002) dark-field image, (C) a (100) dark-field image

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Annular-slot arrays as far-infrared bandpass filters.

    PubMed

    Krug, P A; Dawes, D H; McPhedran, R C; Wright, W; Macfarlane, J C; Whitbourn, L B

    1989-09-01

    Arrays of both annular and square annular slots in a conducting sheet on a dielectric substrate have been fabricated photolithographically. The structures are shown to behave as bandpass filters in the far infrared, with a resonant wavelength slightly larger than the average circumference or perimeter of the slot. The measured far-infrared transmittance of the annular array is approximately 76% of that predicted by theory, while its resonant frequency agrees with theory to within 5%.

  16. Radio frequency eddy current losses for an annular conductor in MRI: theory and applications.

    PubMed

    McRobbie, D W

    1993-01-01

    A theoretical derivation of the equivalent loading resistance of an annular volume conductor within a magnetic resonance imaging radio frequency (RF) coil is presented. Theoretical predictions of the magnitude of the load resistance agree well with measurement over a range of frequencies. The loading resistance is proportional to the sample conductivity, the frequency and coil sensitivity squared, and depends strongly upon the sample dimensions. The orientation of the magnetic vector potential for the specific coil geometry is also important. An experimental comparison of loading by annular and cylindrical objects with the human head over the imaging frequency range is made. Cylindrical test objects are adversely affected by the skin effect. The optimum means of simulating RF induced losses for quality assurance and performance evaluation is discussed in the light of these results.

  17. Resolution enhancement of pump-probe microscopy with an inverse-annular spatial filter

    NASA Astrophysics Data System (ADS)

    Kobayashi, T.; Kawasumi, K.; Miyazaki, J.; Nakata, K.

    2016-12-01

    We have introduced a pupil filter, an inverse-annular pupil filter in a pump-probe photothermal microscope, which provides resolution enhancement in three dimensions. The resolution is probed to be improved in lateral and axial resolution by imaging experiment using 20 nm gold nanoparticles. The improvement in X (perpendicular to the common pump and probe polarization direction), Y (parallel to the polarization direction), and Z (axial direction) are by 15±6, 8±8, and 21±2 % from the resolution without a pupil filter. The resolution enhancement is even better than the calculation using vector field, which predicts the corresponding enhancement of 11, 8, and 6 %. The discussion is made to explain the unexpected results. We also demonstrate the photothermal imaging of thick biological samples (cells from rabbit intestine and kidney) stained with hematoxylin and eosin dye with the inverse-annular filter.

  18. Functional specifications of the annular suspension pointing system, appendix A

    NASA Technical Reports Server (NTRS)

    Edwards, B.

    1980-01-01

    The Annular Suspension Pointing System is described. The Design Realization, Evaluation and Modelling (DREAM) system, and its design description technique, the DREAM Design Notation (DDN) is employed.

  19. Arcuate, annular, and polycyclic inflammatory and infectious lesions.

    PubMed

    Sharma, Amit; Lambert, Phelps J; Maghari, Amin; Lambert, W Clark

    2011-01-01

    Common shapes encountered in dermatologic diseases include linear, nummular, annular, polycyclic, and arciform. The last three have a relatively restricted differential, which must be entirely explored. It is not uncommon for a single disease to present in annular, arciform or polycyclic configurations; moreover, the lesions may evolve from being arciform to annular and then become polycyclic. Regardless, recognizing the arrangement of the defect will undoubtedly help in making a diagnosis and guiding subsequent management. We explore diseases that often present in annular, arciform, and/or polycyclic forms.

  20. 77 FR 72826 - Application(s) for Duty-Free Entry of Scientific Instruments

    Federal Register 2010, 2011, 2012, 2013, 2014

    2012-12-06

    ..., and to obtain atomic number contrast, or Z- contrast, images using the high angle annular dark field... instrument will be used to fabricate plasmonic structures that can trap sub-5-nm nanoparticles,...

  1. Tunable extended depth of field using a liquid crystal annular spatial filter.

    PubMed

    Klapp, Iftach; Solodar, Asi; Abdulhalim, Ibrahim

    2014-03-15

    A tunable extended depth of field (EDOF) imaging is presented using temporal multiplexing and a low-cost eight-ring, annular liquid crystal spatial light modulator. By changing between different phase profiles in the pupil plane of a lens we perform several levels of EDOF. Using these levels as a "database" it is shown by temporal multiplexing how to decompose tunable levels of EDOF.

  2. Full field frequency domain common path optical coherence tomography with annular aperture

    NASA Astrophysics Data System (ADS)

    Abdulhalim, I.; Friedman, Ron; Liraz, Lior; Dadon, Ronen

    2007-07-01

    Theoretical and experimental results are presented using the common path Mirau interference microscope and using the Linnik microscope with annular masks to increase the depth of field. The competence between the spatial and temporal coherence was investigated theoretically and confirmed experimentally. Phase imaging of onion epidermis cells was presented showing the possibility of obtaining profiles of the cells. Frequency domain OCT was shown to be possible using full field setup.

  3. Concentration Measurements in a Cold Flow Model Annular Combustor Using Laser Induced Fluorescence

    NASA Technical Reports Server (NTRS)

    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.

  4. Finite stretching of an annular plate.

    NASA Technical Reports Server (NTRS)

    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.

  5. Annular pancreas associated with duodenal carcinoma

    PubMed Central

    Brönnimann, Enrico; Potthast, Silke; Vlajnic, Tatjana; Oertli, Daniel; Heizmann, Oleg

    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. Duodenopancreatectomy revealed a duodenal adenocarcinoma, surrounded by an incomplete AP. Thus, co-existent malignancy with AP can be present without obstructive jaundice and without being visible through preoperative diagnostics. PMID:20593508

  6. Duration test of an annular colloid thruster.

    NASA Technical Reports Server (NTRS)

    Perel, J.; Mahoney, J. F.; Daley, H. L.

    1972-01-01

    An annular colloid thruster was continuously operated for 1023 hours. Performance was stable with no sparking and negligible drain currents observed. An average thrust of 25.1 micropounds and an average specific impulse of 1160 seconds were obtained at an accelerating voltage of 15 k he thruster exhaust beam was continuously neutralized using electrons and electrostatic vectoring was demonstrated periodically. The only clear trend with time was an increase in specific impulse during the last third of the test period. From these results the thruster lifetime was estimated to be over an order of magnitude greater than the test duration.

  7. Displacement separations by continuous annular chromatography

    SciTech Connect

    DeCarli, J.P. II; Carta, G. ); Byers, C.H. . Chemical Technology Div.)

    1988-01-01

    Continuous annular chromatography (CAC) has been introduced as an effective means of carrying out chromatographic separations in a truly continuous manner. Process applications have been demonstrated. In this work the authors demonstrate how CAC can be operated for displacement development separations. In this mode of operation of the apparatus separation and concentration of multicomponent mixtures can be obtained simultaneously and continuously. Experimental results and model simulations for this novel separation device are presented along with a comparison of different modes of operation and a discussion of industrial applications.

  8. The Annular Momentum Control Device (AMCD)

    NASA Technical Reports Server (NTRS)

    Anderson, W. W.; Groom, N. J.

    1975-01-01

    An annular momentum control device consisting principally of a spinning rim, a set of noncontacting magnetic bearings for supporting the rim, a noncontacting electric motor for driving the rim, and, for some applications, one or more gimbals is described. The device is intended for applications where requirements for control torque and momentum storage exist. Hardware requirements and potential unit configurations are discussed. Theoretical considerations for the passive use of the device are discussed. Potential applications of the device in other than passive configurations for the attitude control, stabilization, and maneuvering of spacecraft are reported.

  9. Seeing double: annular diaper rash in twins.

    PubMed

    Sommer, Lacy L; Manders, Steven M

    2015-01-01

    We report a case of dichorionic, diamniotic twins who developed similar erythematous, annular, erosive plaques in the inguinal folds in the first few weeks of life that were refractory to topical antifungals and oral antibiotics. The twins were found to have high transaminase levels, antinuclear antibody positivity, and anti-SSS/Ro) and anti-SSB/La autoantibodies. The rash resolved without scarring by 7 months of age with the use of low-potency topical corticosteroids. We suggest that physicians consider neonatal lupus erythematosus in neonates with atypical eruptions occurring in sun-protected skin.

  10. Wave turbulence in annular wave tank

    NASA Astrophysics Data System (ADS)

    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.

  11. Nonlinear features of Northern Annular Mode variability

    NASA Astrophysics Data System (ADS)

    Fu, Zuntao; Shi, Liu; Xie, Fenghua; Piao, Lin

    2016-05-01

    Nonlinear features of daily Northern Annular Mode (NAM) variability at 17 pressure levels are quantified by two different measures. One is nonlinear correlation, and the other is time-irreversible symmetry. Both measures show that there are no significant nonlinear features in NAM variability at the higher pressure levels, however as the pressure level decreases, the strength of nonlinear features in NAM variability becomes predominant. This indicates that in order to reach better prediction of NAM variability in the lower pressure levels, nonlinear features must be taken into consideration to build suitable models.

  12. Atomic-level imaging of Mo-V-O complex oxide phase intergrowth, grain boundaries, and defects using HAADF-STEM

    PubMed Central

    Pyrz, William D.; Blom, Douglas A.; Sadakane, Masahiro; Kodato, Katsunori; Ueda, Wataru; Vogt, Thomas; Buttrey, Douglas J.

    2010-01-01

    In this work, we structurally characterize defects, grain boundaries, and intergrowth phases observed in various Mo-V-O materials using aberration-corrected high-angle annular dark-field (HAADF) imaging within a scanning transmission electron microscope (STEM). Atomic-level imaging of these preparations clearly shows domains of the orthorhombic M1-type phase intergrown with the trigonal phase. Idealized models based on HAADF imaging indicate that atomic-scale registry at the domain boundaries can be seamless with several possible trigonal and M1-type unit cell orientation relationships. The alignment of two trigonal domains separated by an M1-type domain or vice versa can be predicted by identifying the number of rows/columns of parallel symmetry operators. Intergrowths of the M1 catalyst with the M2 phase or with the Mo5O14-type phase have not been observed. The resolution enhancements provided by aberration-correction have provided new insights to the understanding of phase equilibria of complex Mo-V-O materials. This study exemplifies the utility of STEM for the characterization of local structure at crystalline phase boundaries. PMID:20308579

  13. Annular and Total Solar Eclipses of 2010

    NASA Technical Reports Server (NTRS)

    Espenak, Fred; Anderson, J.

    2008-01-01

    While most NASA eclipse bulletins cover a single eclipse, this publication presents predictions for two solar eclipses during 2010. This has required a different organization of the material into the following sections. Section 1 -- Eclipse Predictions: The section consists of a general discussion about the eclipse path maps, Besselian elements, shadow contacts, eclipse path tables, local circumstances tables, and the lunar limb profile. Section 2 -- Annular Solar Eclipse of 2010 Ja n 15: The section covers predictions and weather prospects for the annular eclipse. Section 3 -- Total Solar Eclipse of 2010 Jul 11: The se ction covers predictions and weather prospects for the total eclipse. Section 4 -- Observing Eclipses: The section provides information on eye safety, solar filters, eclipse photography, and making contact timings from the path limits. Section 5 -- Eclipse Resources: The final section contains a number of resources including information on the IAU Working Group on Eclipses, the Solar Eclipse Mailing List, the NASA eclipse bulletins on the Internet, Web sites for the two 2010 eclipses, and a summary identifying the algorithms, ephemerides, and paramete rs used in the eclipse predictions.

  14. Signatures of an annular Fermi sea

    NASA Astrophysics Data System (ADS)

    Jo, Insun; Liu, Yang; Pfeiffer, L. N.; West, K. W.; Baldwin, K. W.; Shayegan, M.; Winkler, R.

    2017-01-01

    The concept of a Fermi surface, the constant-energy surface containing all the occupied electron states in momentum, or wave-vector (k ) , space plays a key role in determining electronic properties of conductors. In two-dimensional (2D) carrier systems, the Fermi surface becomes a contour which, in the simplest case, encircles the occupied states. In this case, the area enclosed by the contour, which we refer to as the Fermi sea (FS), is a simple disk. Here we report the observation of an FS with a new topology, namely, an FS in the shape of an annulus. Such an FS is expected in a variety of 2D systems where the energy band dispersion supports a ring of extrema at finite k , but its experimental observation has been elusive. Our study provides (1) theoretical evidence for the presence of an annular FS in 2D hole systems confined to wide GaAs quantum wells and (2) experimental signatures of the onset of its occupation as an abrupt rise in the sample resistance, accompanied by a sudden appearance of Shubnikov-de Haas oscillations at an unexpectedly high frequency whose value does not simply correspond to the (negligible) density of holes contained within the annular FS.

  15. Controlling the pressure within an annular volume of a wellbore

    DOEpatents

    Hermes, Robert E.; Gonzalez, Manuel E.; Llewellyn, Brian C.; Bloys, James B.

    2010-06-29

    A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

  16. Controlling the pressure within an annular volume of a wellbore

    DOEpatents

    Hermes, Robert E.; Gonzalez, Manuel E.; Llewellyn, Brian C.; Bloys, James B.

    2011-01-18

    A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

  17. Controlling the pressure within an annular volume of a wellbore

    SciTech Connect

    Hermes, Robert E.; Gonzalez, Manuel E.; Llewellyn, Brian C.; Bloys, James B.; Coates, Don M.

    2011-06-21

    A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

  18. Controlling the pressure within an annular volume of a wellbore

    SciTech Connect

    Hermes, Robert E.; Gonzalez, Manuel E.; Llewellyn, Brian C.; Bloys, James B.; Coates, Don M.

    2011-05-31

    A process is described for replacing at least a portion of the liquid within the annular volume of a casing system within a wellbore with a second liquid. The second liquid is preselected to provide a measure of control of the pressure within the annular volume as the fluid within the volume is being heated.

  19. Localized interstitial granuloma annulare induced by subcutaneous injections for desensitization.

    PubMed

    Spring, Philipp; Vernez, Maxime; Maniu, Christa-Maria; Hohl, Daniel

    2013-06-15

    We describe a patient with interstitial granuloma annulare associated with subcutaneous injection therapy (SIT) for desensitization to a type I allergy. Asymptomatic, erythematous, violaceous annular patches were located at the injection sites on both her arms. Medical history revealed perennial rhinoconjonctivitis treated with SIT (Phostal Stallergen® cat 100% and D. pteronyssinus/D.farinae 50%:50%).

  20. Vortex beam based more stable annular laser guide star

    NASA Astrophysics Data System (ADS)

    Luo, Ruiyao; Cui, Wenda; Li, Lei; Sun, Quan; He, Yulong; Wang, Hongyan; Ning, Yu; Xu, Xiaojun

    2016-11-01

    We present an annular laser guide star (LGS) concept for large ground-based telescopes in this paper. The more stable annular LGS is generated by turbulence-resisted vortex beam. In the uplink, a vortex beam tends to wander more slightly than a Gaussian beam does in atmospheric turbulence. This may enable an annular LGS to wander more slightly than a traditional Gaussian beam generated LGS does, which would ease the burden of uplink tip-tilt mirror and benefit a dynamical closed-loop adaptive optics system. We conducted numerical simulation to validate the feasibility of this concept. And we have gotten 31% reduced variance of spot wandering of annular LGS. Besides, we set up a spatial light modulator based laser guide star simulator for beam propagation in turbulent atmosphere to experimentally test the annular LGS concept. Preliminary experimental results are given. To the best of our knowledge, it is the first time this concept is formulated.

  1. Research of annular polishing asymmetric ZnS plane window

    NASA Astrophysics Data System (ADS)

    Guo, Weijin; Tong, Yi; Jin, Yuzhu; Lin, Nana

    2016-10-01

    Due the annular polishing technology for planar optical components do not have the sharp selectivity, annular polishing technology is a very import process to fabricate irregular planar elements which with high precision surface shape and low surface roughness. According to the characteristics of annular polishing, the zns asymmetric plane window annular polishing process and key technical parameters control was researched. In this paper, one pair of asymmetric planar ZnS window parts were machined which diagonal length is 147mm, through technology experiments, obtained process test samples. The surface figures of the plane zns window are measured by a Zygo interferometer and the reflect wavefront P-V value is better than 1.5λ, the reflect wavefront local error rms value is better than 0.05λ (λ=632.8nm). Experiments results demonstrate the effectiveness of annular processing technology was used to manufacture zinc sulfide asymmetric shape plane window.

  2. Vaginal delivery through annular placenta – case report

    PubMed Central

    Živković, Nikica; Krezo, Stipe; Matijević, Ratko; Živković, Krešimir

    2013-01-01

    Annular placenta is an extremely rare morphological type of human placenta. It is commonly related to placental vessel abnormalities frequently causing antenatal and postnatal hemorrhage and operative delivery. Gravida 4 para 1 had an uneventful course of pregnancy and normal vaginal delivery followed by moderate postpartum hemorrhage. Hemorrhage was found to be local in origin but the placenta was annular in shape and the newborn was delivered through one of the openings. Annular placenta was not recognized before delivery. Its implantation site was in the lower uterine segment but high enough to allow the passage of the fetus through its annular defect and vaginal birth. To our knowledge, this is a first report of annular placenta ending in normal vaginal delivery. PMID:23630149

  3. Mitral Annular Systolic Velocities Predict Left Ventricular Wall Motion Abnormality During Dobutamine Stress Echocardiography

    PubMed Central

    Sharif, Dawod; Sharif-Rasslan, Amal; Shahla, Camilia

    2011-01-01

    Background Longitudinal systolic left ventricular contraction is complementary to the radial performance and can be assessed using tissue Doppler imaging (TDI). This study was performed to evaluate the contribution of mitral annular systolic velocities using TDI after dobutamine stress echocardiography (DSE). Methods and Results Fifty subjects with suspected coronary artery disease and chest pain were examined, using DSE as usual, as well as TDI imaging of the mitral annulus at the septal, lateral, inferior, anterior, posterior regions and the proximal anteroseptal region from the apical views, before and immediately after DSE. In 24 subjects the study was normal, while wall motion abnormality was seen in 26, 9 of them only after DSE. Mitral annular systolic velocity at the 6 locations increased significantly after DSE both in normal subjects and in those with wall motion abnormality (WMA). After DSE mitral annular septal systolic velocity in normals, 19.2 ± 3.8 cm/sec, was higher than in those with WMA, 14.6 ± 2.5 cm/sec, P < 0.0003. Post-DSE mitral systolic velocity was senstive and accurate in predicting WMA. Conclusions Systolic mitral TDI velocities increase after DSE, however to a lesser extent in those with wall motion abnormality, and can differentiate them from normal subjects.

  4. A dark-field microscope for background-free detection of resonance fluorescence from single semiconductor quantum dots operating in a set-and-forget mode

    SciTech Connect

    Kuhlmann, Andreas V.; Houel, Julien; Warburton, Richard J.; Brunner, Daniel; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D.

    2013-07-15

    Optically active quantum dots, for instance self-assembled InGaAs quantum dots, are potentially excellent single photon sources. The fidelity of the single photons is much improved using resonant rather than non-resonant excitation. With resonant excitation, the challenge is to distinguish between resonance fluorescence and scattered laser light. We have met this challenge by creating a polarization-based dark-field microscope to measure the resonance fluorescence from a single quantum dot at low temperature. We achieve a suppression of the scattered laser exceeding a factor of 10{sup 7} and background-free detection of resonance fluorescence. The same optical setup operates over the entire quantum dot emission range (920–980 nm) and also in high magnetic fields. The major development is the outstanding long-term stability: once the dark-field point has been established, the microscope operates for days without alignment. The mechanical and optical designs of the microscope are presented, as well as exemplary resonance fluorescence spectroscopy results on individual quantum dots to underline the microscope's excellent performance.

  5. A dark-field microscope for background-free detection of resonance fluorescence from single semiconductor quantum dots operating in a set-and-forget mode.

    PubMed

    Kuhlmann, Andreas V; Houel, Julien; Brunner, Daniel; Ludwig, Arne; Reuter, Dirk; Wieck, Andreas D; Warburton, Richard J

    2013-07-01

    Optically active quantum dots, for instance self-assembled InGaAs quantum dots, are potentially excellent single photon sources. The fidelity of the single photons is much improved using resonant rather than non-resonant excitation. With resonant excitation, the challenge is to distinguish between resonance fluorescence and scattered laser light. We have met this challenge by creating a polarization-based dark-field microscope to measure the resonance fluorescence from a single quantum dot at low temperature. We achieve a suppression of the scattered laser exceeding a factor of 10(7) and background-free detection of resonance fluorescence. The same optical setup operates over the entire quantum dot emission range (920-980 nm) and also in high magnetic fields. The major development is the outstanding long-term stability: once the dark-field point has been established, the microscope operates for days without alignment. The mechanical and optical designs of the microscope are presented, as well as exemplary resonance fluorescence spectroscopy results on individual quantum dots to underline the microscope's excellent performance.

  6. Annular array and method of manufacturing same

    DOEpatents

    Day, Robert A.

    1989-01-01

    A method for manufacturing an annular acoustic transducer array from a plate of transducer material, which enables production of precision aligned arrays at low cost. The circular plate is sawed along at least two lines that are radial to the axis of the plate. At steps along each radial cut, the plate is rotated first in one direction and then in an opposite direction by a predetermined angle such as slightly less than 90.degree.. The cuts result in the forming of several largely ring-shaped lands, each largely ring-shaped land being joined to the other rings of different radii by thin portions of the plate, and each ring being cut into segments. The bridges that join different rings, hold the transducer together until it can be mounted on a lens.

  7. Dense annular flows of granular media

    NASA Astrophysics Data System (ADS)

    de Ryck, Alain; Louisnard, Olivier

    2013-06-01

    Dense granular flows constitute an important topic for geophysics and process engineering. To describe them, a rheology based on the coaxiality between the stress and strain tensors with a Mohr-Coulomb yield criterion has been proposed. We propose here an analytic study of flows in an annular cell, with this rheology. This geometry is relevant for a series of powder rheometers or mixing devices, but the discussion is focused on the split-bottom geometry, for which the internal flow has been investigated by NMR technique. In this case, the full resolution of the velocity and stress fields allow to localize the shear deformations. The theoretical results obtained for the latter are compared with the torque measurements by Dijksman et al. [Phys. Rev. E, 82 (2010) 060301].

  8. Annular Ion Engine Concept and Development Status

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.

    2016-01-01

    The Annular Ion Engine (AIE) concept represents an evolutionary development in gridded ion thruster technology with the potential for delivering revolutionary capabilities. It has this potential because the AIE concept: (a) enables scaling of ion thruster technology to high power at specific impulse (Isp) values of interest for near-term mission applications, 5000 sec; and (b) it enables an increase in both thrust density and thrust-to-power (FP) ratio exceeding conventional ion thrusters and other electric propulsion (EP) technology options, thereby yielding the highest performance over a broad range in Isp. The AIE concept represents a natural progression of gridded ion thruster technology beyond the capabilities embodied by NASAs Evolutionary Xenon Thruster (NEXT) [1]. The AIE would be appropriate for: (a) applications which require power levels exceeding NEXTs capabilities (up to about 14 kW [2]), with scalability potentially to 100s of kW; and/or (b) applications which require FP conditions exceeding NEXTs capabilities.

  9. Separation of sugars by continuous annular chromatography

    SciTech Connect

    Howard, A.J.; Carta, G.; Byers, C.H.

    1987-08-01

    Continuous chromatographic separations of aqueous fructose-glucose-sucrose solutions have been investigated in a laboratory-scale continuous annular chromatograph (CAC) using calcium-exchanged Dowex 50W-X8 resin. Comparative studies have also been conducted using a conventional fixed-bed column packed with the same resin. Complete resolution of fructose-glucose mixtures could be obtained both in a 60-cm-long CAC and in a conventional column of the same length with a sugar feed concentration of up to 200 g/L. Partial resolution of sucrose in three component mixtures was also obtained, and the three sugars were completely separated from added higher-molecular-weight saccharides. Results have been analyzed in terms of approximate linear chromatographic theories and orthogonal collocation of exact mass transfer model equations for fixed and rotating beds. A systematic, comparative evaluation of factors affecting process performance and design procedures is presented.

  10. Annular nanoantenna on fibre micro-axicon.

    PubMed

    Grosjean, T; Fahys, A; Suarez, M; Charraut, D; Salut, R; Courjon, D

    2008-02-01

    In this paper, we propose to extend the concept of loop antenna to the optical domain. The aim is to develop a new generation of optical nanocollectors that are sensitive to specific electric or magnetic vectorial field components. For validating our approach, a preliminary one-micron-diameter gold nanoring is micromachined on the apex of a cone lens obtained from a tapered optical fibre. It is shown that such a nano-object behaves as a nano-antenna able to detect the longitudinal electric field from a Bessel beam in radial polarization and the longitudinal magnetic component from a Bessel beam in azimuthal polarization. In the latter case, the annular nano-antenna exhibits the properties of an optical inductance.

  11. Simulation of cryogenic turbopump annular seals

    NASA Technical Reports Server (NTRS)

    Palazzolo, Alan B.

    1992-01-01

    The goal of the current work is to develop software that can accurately predict the dynamic coefficients, forces, leakage and horsepower loss for annular seals which have a potential for affecting the rotordynamic behavior of the pumps. The fruit of last year's research was the computer code SEALPAL which included capabilities for linear tapered geometry, Moody friction factor and inlet pre-swirl. This code produced results which in most cases compared very well with check cases presented in the literature. TAMUSEAL Icode, which was written to improve SEALPAL by correcting a bug and by adding more accurate integration algorithms and additional capabilities, was then used to predict dynamic coefficients and leakage for the NASA/Pratt and Whitney Alternate Turbopump Development (ATD) LOX Pump's seal.

  12. Trauma-related papular granuloma annular.

    PubMed

    Hu, Stephanie W; Kaplan, Jennifer; Patel, Rishi R; Kamino, Hideko

    2013-12-16

    Granuloma annulare (GA) is a benign, granulomatous disease with several clinical manifestations, which include localized, generalized, perforating, subcutaneous, patch, papular, and linear forms. We report a case of papular GA of the dorsal aspects of the hands that arose after repeated, direct trauma to the site of subsequent involvement. Although multiple etiologies for GA have been proposed, which include ultraviolet light, arthropod bites, trauma, tuberculin skin tests, viral infections, and PUVA photochemotherapy, the underlying pathogenesis of the disorder remains unclear. However, owing to the key histopathologic findings of focal collagen and elastic fiber degeneration and mucin deosition in GA, it is not surprising that cutaneous trauma may have played a role in connective tissue injury, subsequent degeneration, and the production of a granulomatous response with increased mucin deposition.

  13. Annular MHD Physics for Turbojet Energy Bypass

    NASA Technical Reports Server (NTRS)

    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).

  14. Actinic Granuloma Annulare With Scarring and Open Comedones.

    PubMed

    Gavioli, Cfb; Valente, Nys; Sangueza, M; Nico, M M

    2017-02-14

    Actinic granuloma and annular elastolytic giant cell granuloma are variants of granuloma annulare affecting, respectively, sun-exposed and sun-covered skin sites on where, besides classical findings, abundant elastophagocytosis is observed. Here, we report a case of exuberant actinic granuloma annulare that, in addition to extensive scarring, showed multiple overlying open comedones. Markedly dilated follicular infundibula filled with compact masses of laminated keratinous material were observed in proximity to dermal inflammation composed of many histiocytes and multinucleated giant cells in close association with degenerated elastic fibers and abundant elastophagocytosis.

  15. CROSS-DISCIPLINARY PHYSICS AND RELATED AREAS OF SCIENCE AND TECHNOLOGY: Manipulation of Nanoparticles Using Dark-Field-Illumination Optical Tweezers with Compensating Spherical Aberration

    NASA Astrophysics Data System (ADS)

    Zhou, Jin-Hua; Tao, Run-Zhe; Hu, Zhi-Bin; Zhong, Min-Cheng; Wang, Zi-Qiang; Cai, Jun; Li, Yin-Mei

    2009-06-01

    Based on our previous investigation of optical tweezers with dark field illumination [Chin. Phys. Lett. 25(2008)329], nanoparticles at large trap depth are 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.

  16. Dark-field-based observation of single-nanoparticle dynamics on a supported lipid bilayer for in situ analysis of interacting molecules and nanoparticles.

    PubMed

    Lee, Young Kwang; Kim, Sungi; Nam, Jwa-Min

    2015-01-12

    Observation of single plasmonic nanoparticles in reconstituted biological systems allows us to obtain snapshots of dynamic processes between molecules and nanoparticles with unprecedented spatiotemporal resolution and single-molecule/single-particle-level data acquisition. This Concept is intended to introduce nanoparticle-tethered supported lipid bilayer platforms that allow for the dynamic confinement of nanoparticles on a two-dimensional fluidic surface. The dark-field-based long-term, stable, real-time observation of freely diffusing plasmonic nanoparticles on a lipid bilayer enables one to extract a broad range of information about interparticle and molecular interactions throughout the entire reaction period. Herein, we highlight important developments in this context to provide ideas on how molecular interactions can be interpreted by monitoring dynamic behaviors and optical signals of laterally mobile nanoparticles.

  17. CNN-coupled Humanoid Panoramic Annular Lens (PAL)-Optical System for Military Applications (Feasibility Study)

    NASA Astrophysics Data System (ADS)

    Greguss, Pal

    2002-01-01

    This report results from a contract tasking OPTOPAL Panoramic Metrology Consulting as follows: This investigation will consist of adaptation of a Hungarian-developed single-piece imaging block, the Panoramic Annular Lens (PAL) and the CNN chip for a few military applications. A polar beam splitter will be placed immediately after the relay lens to obtain two image planes, one will be used by the existing 64X64 CNN-UM focal plane array processor chip. The other image plane will be projected on the space-variant CMOS retina-like digital camera GIOTTO. Using this configuration enables us to compensate for the relatively low pixel number of the CNN-UM array processor; further it will allow a real time switching from log-polar imaging to regular imaging and allow for the design of the humanoid PAL optical system.

  18. Principle of radial transport in low temperature annular plasmas

    NASA Astrophysics Data System (ADS)

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2015-07-01

    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.

  19. Principle of radial transport in low temperature annular plasmas

    SciTech Connect

    Zhang, Yunchao Charles, Christine; Boswell, Rod

    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.

  20. Virtual cathode microwave generator having annular anode slit

    DOEpatents

    Kwan, Thomas J. T.; Snell, Charles M.

    1988-01-01

    A microwave generator is provided for generating microwaves substantially from virtual cathode oscillation. Electrons are emitted from a cathode and accelerated to an anode which is spaced apart from the cathode. The anode has an annular slit therethrough effective to form the virtual cathode. The anode is at least one range thickness relative to electrons reflecting from the virtual cathode. A magnet is provided to produce an optimum magnetic field having the field strength effective to form an annular beam from the emitted electrons in substantial alignment with the annular anode slit. The magnetic field, however, does permit the reflected electrons to axially diverge from the annular beam. The reflected electrons are absorbed by the anode in returning to the real cathode, such that substantially no reflexing electrons occur. The resulting microwaves are produced with a single dominant mode and are substantially monochromatic relative to conventional virtual cathode microwave generators.

  1. Elastic-plastic analysis of annular plate problems using NASTRAN

    NASA Technical Reports Server (NTRS)

    Chen, P. C. T.

    1983-01-01

    The plate elements of the NASTRAN code are used to analyze two annular plate problems loaded beyond the elastic limit. The first problem is an elastic-plastic annular plate loaded externally by two concentrated forces. The second problem is stressed radially by uniform internal pressure for which an exact analytical solution is available. A comparison of the two approaches together with an assessment of the NASTRAN code is given.

  2. Description of a laboratory model Annular Momentum Control Device (AMCD)

    NASA Technical Reports Server (NTRS)

    Groom, N. J.

    1984-01-01

    The basic concept of the Annular Momentum Control Device (AMCD) is that of a rotating annular rim suspended by noncontacting magnetic bearings and driven by a noncontacting electromagnetic spin motor. The purpose of this paper is to highlight some of the design requirements for AMCD's in general and describe how these requirements were met in the implementation of laboratory test model AMCD. An AMCD background summary is presented.

  3. Annular elastolytic giant cell granuloma: A report of 10 cases

    PubMed Central

    Arora, Sandeep; Malik, Ajay; Patil, Chetan; Balki, Anil

    2015-01-01

    Annular elastolytic giant cell granuloma initially described by O’Brien in 1975 is a disorder of uncertain etiopathogenesis presenting with annular erythematous plaques predominantly on the sun-exposed areas. Hisptopathologically, it is characterized by elastin degenration, multinucleate giant cells, and elastophagocytosis. The authors came across 10 such cases, which were managed with hydroxychloroquine resulting in complete resolution in 4–6 months. PMID:26904442

  4. Experimental Results for an Annular Aerospike with Differential Throttling

    NASA Technical Reports Server (NTRS)

    Ruf, Joseph H.; McDaniels, David M.

    2005-01-01

    A) MSFC funded an internal study on Altitude Compensating Nozzles: 1) Develop an ACN design and performance prediction tool. 2) Design, build and test cold flow ACN nozzles. 3) An annular aerospike nozzle was designed and tested. 4) Incorporated differential throttling to assess Thrust Vector Control. B) Objective of the test hardware: 1) Provide design tool verification. 2) Provide benchmark data for CFD calculations. 3) Experimentally measure side force, or TVC, for a differentially throttled annular aerospike.

  5. Evaluation of a laboratory test model annular momentum control device

    NASA Technical Reports Server (NTRS)

    Groom, N. J.; Terray, D. E.

    1978-01-01

    A 4068 Nm Sec laboratory test model annular momentum control device (AMCD) was described and static and dynamic test results were presented. An AMCD is a spinning annular rim suspended by noncontacting magnetic bearings and powered by a noncontacting linear electromagnetic motor. Test results include spin motor torque characteristics and spin motor and magnetic bearing drag losses. Limitations of some of the design approaches taken was also discussed.

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

    PubMed

    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.

  7. Impulsively started, steady and pulsated annular inflows

    NASA Astrophysics Data System (ADS)

    Abdel-Raouf, Emad; Sharif, Muhammad A. R.; Baker, John

    2017-04-01

    A computational investigation was carried out on low Reynolds number laminar inflow starting annular jets using multiple blocking ratios and atmospheric ambient conditions. The jet exit velocity conditions are imposed as steady, unit pulsed, and sinusoidal pulsed while the jet surroundings and the far-field jet inlet upstream conditions are left atmospheric. The reason is to examine the flow behavior in and around the jet inlet under these conditions. The pulsation mode behavior is analyzed based on the resultant of the momentum and pressure forces at the entry of the annulus, the circulation and vortex formation, and the propulsion efficiency of the inflow jets. The results show that under certain conditions, the net force of inflow jets (sinusoidal pulsed jets in particular) could point opposite to the flow direction due to the adverse pressure drops in the flow. The propulsion efficiency is also found to increase with pulsation frequency and the sinusoidal pulsed inflow jets are more efficient than the unit pulsed inflow jets. In addition, steady inflow jets did not trigger the formation of vortices, while unit and sinusoidal pulsed inflow jets triggered the formation of vortices under a certain range of frequencies.

  8. Solar cycle modulation of Southern Annular Mode

    NASA Astrophysics Data System (ADS)

    Kuroda, Yuhji

    2016-04-01

    Climate is known to be affected by various factors, including oceanic changes and volcanic eruptions. 11-year solar cycle change is one of such important factors. Observational analysis shows that the winter-mean North Atlantic Oscillation (NAO) and late-winter/spring Southern Annular Mode (SAM) show structural modulation associated with 11-year solar cycle. In fact, these signals tend to extend from surface to upper stratosphere and persistent longer period only in the High Solar (HS) years. In the present study, we used 35-year record of ERA-Interim reanalysis data and performed wave-energy and momentum analysis on the solar-cycle modulation of the SAM to examine key factors to create such solar-SAM relationship. It is found that enhanced wave-mean flow interaction tends to take place in the middle stratosphere in association with enhanced energy input from diabatic heating on September only in HS years. The result suggests atmospheric and solar conditions on September are keys to create solar-SAM relationship.

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

    PubMed

    Dicken, A J; Evans, J P O; Rogers, K D; Stone, N; Greenwood, C; Godber, S X; Prokopiou, D; Clement, J G; Lyburn, I D; Martin, R M; Zioupos, P

    2015-08-07

    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.

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

    NASA Astrophysics Data System (ADS)

    Dicken, A. J.; Evans, J. P. O.; Rogers, K. D.; Stone, N.; Greenwood, C.; Godber, S. X.; Prokopiou, D.; Clement, J. G.; Lyburn, I. D.; Martin, R. M.; Zioupos, P.

    2015-08-01

    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.

  11. Critical heat flux estimation for annular channel geometry

    NASA Astrophysics Data System (ADS)

    Pagh, Richard T.

    Critical Heat Flux (CHF) is an important safety parameter for the design of nuclear reactors. The most commonly used predictive tool for determination of CHF is a look-up table developed using tube data with an average hydraulic test diameter of 8 mm. There exist in the world today nuclear reactors whose geometry is annular, not tubular, and whose hydraulic diameter is significantly smaller than 8 mm. In addition, any sub-channel thermal hydraulic model of fuel assemblies is annular and not tubular. Comparisons were made between this predictive tool and annular correlations developed from test data. These comparisons showed the look-up table over-predicts the CHF values for annular channels, thus questioning its ability to perform correct safety evaluations. Since no better tool exists to predict CHF for annular geometry, an effort was undertaken to produce one. A database of open literature annular CHF values was created as a basis for this new tool. By compiling information from eighteen sources and requiring that the data be inner wall, unilaterally, uniformly heated with no spacers or heat transfer enhancement devices, a database of 1630 experimental values was produced. After a review of the data in the database, a new look-up table was created. A look-up table provides localized control of the prediction to overcome sparseness of data. Using Shepard's Method as the extrapolation technique, a regular mesh look-up table was produced using four main variables: pressure, quality, mass flux, and hydraulic diameter. The root mean square error of this look-up table was found to be 0.8267. However, by fixing the hydraulic diameter locations to the database values, the root mean square error was further reduced to 0.2816. This look-up table can now predict CHF values for annular channels over a wide range of fluid conditions.

  12. Multimodal imaging of micron-sized iron oxide particles following in vitro and in vivo uptake by stem cells: down to the nanometer scale.

    PubMed

    Roose, Dimitri; Leroux, Frederic; De Vocht, Nathalie; Guglielmetti, Caroline; Pintelon, Isabel; Adriaensen, Dirk; Ponsaerts, Peter; Van der Linden, Annemie; Bals, Sara

    2014-01-01

    In this study, the interaction between cells and micron-sized paramagnetic iron oxide (MPIO) particles was investigated by characterizing MPIO in their original state, and after cellular uptake in vitro as well as in vivo. Moreover, MPIO in the olfactory bulb were studied 9 months after injection. Using various imaging techniques, cell-MPIO interactions were investigated with increasing spatial resolution. Live cell confocal microscopy demonstrated that MPIO co-localize with lysosomes after in vitro cellular uptake. In more detail, a membrane surrounding the MPIO was observed by high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM). Following MPIO uptake in vivo, the same cell-MPIO interaction was observed by HAADF-STEM in the subventricular zone at 1 week and in the olfactory bulb at 9 months after MPIO injection. These findings provide proof for the current hypothesis that MPIO are internalized by the cell through endocytosis. The results also show MPIO are not biodegradable, even after 9 months in the brain. Moreover, they show the possibility of HAADF-STEM generating information on the labeled cell as well as on the MPIO. In summary, the methodology presented here provides a systematic route to investigate the interaction between cells and nanoparticles from the micrometer level down to the nanometer level and beyond.

  13. A microscopy method for scanning transmission electron microscopy imaging of the antibacterial activity of polymeric nanoparticles on a biofilm with an ionic liquid.

    PubMed

    Takahashi, Chisato; Muto, Shunsuke; Yamamoto, Hiromitsu

    2016-04-18

    In this study, we developed a scanning transmission electron microscopy (STEM) method for imaging the antibacterial activity of organic polymeric nanoparticles (NPs) toward biofilms formed by Staphylococcus epidermidis bacterial cells, for optimizing NPs to treat biofilm infections. The combination of sample preparation method using a hydrophilic ionic liquid (IL) and STEM observation using the cooling holder eliminates the need for specialized equipment and techniques for biological sample preparation. The annular dark-field STEM results indicated that the two types of biodegradable poly-(DL-lactide-co-glycolide) (PLGA) NPs: PLGA modified with chitosan (CS), and clarithromycin (CAM)-loaded + CS-modified PLGA, prepared by emulsion solvent diffusion exhibited different antibacterial activities in nanoscale. To confirm damage to the sample during STEM observation, we observed the PLGA NPs and the biofilm treated with PLGA NPs by both the conventional method and the newly developed method. The optimized method allows microstructure of the biofilm treated with PLGA NPs to be maintained for 25 min at a current flow of 40 pA. The developed simple sample preparation method would be helpful to understand the interaction of drugs with target materials. In addition, this technique could contribute to the visualization of other deformable composite materials at the nanoscale level. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2016.

  14. On the mixing enhancement in annular flows

    NASA Astrophysics Data System (ADS)

    Moradi, H. V.; Floryan, J. M.

    2017-02-01

    The potential for mixing enhancement associated with the use of axisymmetric ribs in annular flows has been analyzed. The enhancement relies on the use of streamwise vortices produced by the centrifugal instability. Conditions leading to the formation of such vortices have been established for a wide range of geometric parameters of interest using linear stability theory. It has been demonstrated that vortices can be formed only in the presence of ribs with O(1) wavelengths. Slopes of the bounding walls in the case of the long wavelength ribs are too small to create centrifugal forces sufficient for flow destabilization. In the case of short wavelength ribs, the slopes become excessively large, resulting in the stream moving away from the wall and becoming rectilinear and, thus, reducing the magnitude of the centrifugal force field. It has been shown that decreasing the annulus' radius reduces the critical Reynolds number when ribs are placed at the inner cylinder but increases when the ribs are placed at the outer cylinder. The onset of the shear-driven instability has been investigated as the resulting travelling waves may interfere with the formation of vortices. It has been shown that the axisymmetric waves play the critical role for annuli with large radii while the spiral waves play the critical role for annuli with small radii. The ribs always reduce the critical Reynolds number for the travelling waves when compared with the onset conditions for smooth annuli. The conduit geometries giving preference to the formation of vortices while avoiding creation of the travelling waves have been identified. It is demonstrated that predictions of flow characteristics determined through the analysis of sinusoidal ribs provide a good approximation of the flow response to ribs of arbitrary shape.

  15. Stratospheric Annular Modes Induced By Stationary Wave Forcing

    NASA Astrophysics Data System (ADS)

    Körnich, H.; Schmitz, G.

    The variability of the winter stratosphere shows distinguishable features in the north- ern and southern hemisphere. Since these differences are based on the different plan- etary waves of the underlying atmosphere, we explore the mechanism how stationary wave forcing in the troposphere can induce a stratospheric Annular Mode using a simple GCM. The model KMCM (Kühlungsborn Mechanistic Circulation Model) extends from the ground up to 60 km height and produces a reasonable winter climate. It takes into account the different large-scale wave forcings in the troposphere as prescribed pro- cesses. This allows us to examine the stratospheric Annular-Mode generation depend- ing on different wave forcings under perpetual January conditions. Principal com- ponent analysis is applied to identify the variability patterns of the geopotential and of the zonally averaged zonal wind. By this way, it is shown that the amplitude and composition of the orographic and thermal eddy forcing determines the stratospheric Annular Mode and the related downward propagation in the temperature field. Further model simplifications are introduced in order to understand the mechanism of the stratospheric AM-generation. Using a linear model version we illuminate the influence of the different wave forcing processes on the Annular Modes. Addition- ally, a constant-troposphere model is used to clarify the importance of transient and stationary waves. Finally, the Annular Mode is interpreted in terms of the dynamical coupling of the troposphere and stratosphere.

  16. Application of Mitral Annular Systolic Displacements and Velocities for the Evaluation of Left Ventricular Systolic Function and Reserve

    PubMed Central

    Sharif, Dawod; Sharif-Rasslan, Amal; Shahla, Camilia; Rosenschein, Uri

    2011-01-01

    Background Mitral annular systolic displacement from M-mode echocardiography and velocity from tissue Doppler imaging reflect subendocardial longitudinal systolic LV performance and may precede radial abnormalities. The aim of this study is to evaluate the utility of mitral annular systolic displacement (D) and velocity (V) during dobutamine stress echocardiography (DSE) in detecting left ventricular (LV) functional reserve and wall motion abnormality (WMA). Methods and Results Fifty-nine subjects, 15 with resting WMA, underwent DSE and measurement of mitral systolic (D) and (V) before and immediately after DSE. Annular septal (D) was lower in those with WMA than in those without, at rest 10.5 ± 4 cm versus 13.2 ± 2 cm, p = 0.015, and after DSE, 11.7 ± 3.8 cm versus 14 ± 2.25 cm, p = 0.036, but without significant change after stress. Annular systolic (V) at rest with WMA was 9.7 ± 1.8 cm/sec and similar to those without, 11.25 ± 2.7 cm/sec. In both groups the velocity increased after DSE, 14.5 ± 4.5 cm/sec, p = 0.025 with WMA and 17.8 ± 3.2 cm/sec, p = 1.99 x 10-10 in those without WMA. Velocities after DSE were lower in those with WMA, p = 2.25 x 10-6. Conclusions To evaluate LV systolic performance mitral annular systolic longitudinal displacement is valuable at rest, but for assessment of LV functional reserve after stress velocities are better.

  17. Non-axisymmetric annular curtain stability

    NASA Astrophysics Data System (ADS)

    Ahmed, Zahir U.; Khayat, Roger E.; Maissa, Philippe; Mathis, Christian

    2013-08-01

    A stability analysis of non-axisymmetric annular curtain is carried out for an axially moving viscous jet subject in surrounding viscous gas media. The effect of inertia, surface tension, gas-to-liquid density ratio, inner-to-outer radius ratio, and gas-to-liquid viscosity ratio on the stability of the jet is studied. In general, the axisymmetric disturbance is found to be the dominant mode. However, for small wavenumber, the non-axisymmetric mode is the most unstable mode and the one likely observed in reality. Inertia and the viscosity ratio for non-axisymmetric disturbances show a similar stability influence as observed for axisymmetric disturbances. The maximum growth rate in non-axisymmetric flow, interestingly, appears at very small wavenumber for all inertia levels. The dominant wavenumber increases (decreases) with inertia for non-axisymmetric (axisymmetric) flow. Gas-to-liquid density ratio, curvature effect, and surface tension, however, exhibit an opposite influence on growth rate compared to axisymmetric disturbances. Surface tension tends to stabilize the flow with reductions of the unstable wavenumber range and the maximum growth rate as well as the dominant wavenumber. The dominant wavenumber remains independent of viscosity ratio indicating the viscosity ratio increases the breakup length of the sheet with very little influence on the size of the drops. The range of unstable wavenumbers is affected only by curvature in axisymmetric flow, whereas all the stability parameters control the range of unstable wavenumbers in non-axisymmetric flow. Inertia and gas density increase the unstable wavenumber range, whereas the radius ratio, surface tension, and the viscosity ratio decrease the unstable wavenumber range. Neutral curves are plotted to separate the stable and unstable domains. Critical radius ratio decreases linearly and nonlinearly with the wavenumber for axisymmetric and non-axisymmetric disturbances, respectively. At smaller Weber numbers, a

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

    PubMed

    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. Development of ITER Divertor Vertical Target with Annular Flow Concept - I: Thermal-Hydraulic Characteristics of Annular Swirl Tube

    SciTech Connect

    Ezato, K.; Dairaku, M.; Taniguchi, M.; Sato, K.; Suzuki, S.; Akiba, M.; Ibbott, C.; Tivey, R.

    2004-12-15

    Thermal-hydraulic tests for pressurized water in an annular tube with a twist fin have been performed to examine its applicability to high-heat-flux components of the International Thermonuclear Experimental Reactor (ITER) divertor. The annular swirl tube consists of two concentric tubes: an outer smooth tube and an inner tube with an external twist fin to enhance heat transfer of the cooling water in the annulus section between the outer and the inner tubes. Critical heat flux (CHF) tests under one-sided-heating conditions show that the annular swirl tube has as high removal limitation as the conventional swirl tube, the dimensions of which are similar to those of the outer tube of the annular swirl tube. A minimum axial velocity of 7.1 m/s is required for 28 MW/m{sup 2}, the ITER design value. Pressure drops in the annulus section and the end return have been measured. The applicability of the existing correlations for heat transfer and CHF to the annular swirl tube has also been examined.

  20. Annular elastolytic giant cell granuloma in association with Hashimoto's thyroiditis

    PubMed Central

    Hassan, Rishi; Arunprasath, P.; Padmavathy, L.; Srivenkateswaran, K.

    2016-01-01

    Annular elastolytic giant cell granuloma (AEGCG) is a rare granulomatous skin disease characterized clinically by annular plaques with elevated borders and atrophic centers found mainly on sun-exposed skin and histologically by diffuse granulomatous infiltrates composed of multinucleated giant cells, histiocytes and lymphocytes in the dermis along with phagocytosis of elastic fibers by multinucleated giant cells. We report a case of AEGCG in a 50-year-old woman and is highlighted for the classical clinical and histological findings of the disease and its rare co-existence with Hashimoto's thyroiditis. PMID:27057492

  1. Flutter Analysis of Annular Cascades in Counter Rotation

    NASA Astrophysics Data System (ADS)

    Nishino, Ryohei; Namba, Masanobu

    The paper studies the effect of neighboring blade rows on flutter characteristics of cascading blades. For this purpose the computation program to calculate the unsteady blade loading based on the unsteady lifting surface theory for contra-rotating annular cascades was formulated and coded. Then a computation program to solve the coupled bending-torsion flutter equation for the contra-rotating annular cascades was also developed. Some results of the flutter analysis are presented. The presence of the neighboring blade row gives rise to significant change in the critical flutter condition when the main acoustic duct mode is of cut-on state.

  2. Topological suppression of optical tunneling in a twisted annular fiber

    SciTech Connect

    Ornigotti, M.; Valle, G. Della; Gatti, D.; Longhi, S.

    2007-08-15

    A classical wave-optics analog of topological (Aharonov-Bohm) suppression of tunneling in a double-well potential on a ring threaded by a magnetic flux is proposed. The optical system consists of a uniformly twisted optical fiber with a structured annular core, in which the fiber twist mimics the role of the magnetic flux in the corresponding quantum-mechanical problem. Light waves trapped in the annular core of the fiber experience an additional topological (Aharonov-Bohm) phase, which may lead to the destruction of optical tunneling at certain values of the twist rate.

  3. Polarization-independent waveguiding with annular photonic crystals.

    PubMed

    Cicek, Ahmet; Ulug, Bulent

    2009-09-28

    A linear waveguide in an annular photonic crystal composed of a square array of annular dielectric rods in air is demonstrated to guide transverse electric and transverse magnetic modes simultaneously. Overlapping of the guided bands in the full band gap of the photonic crystal is shown to be achieved through an appropriate set of geometric parameters. Results of Finite-Difference Time-Domain simulations to demonstrate polarization-independent waveguiding with low loss and wavelength-order confinement are presented. Transmission through a 90 degrees bend is also demonstrated.

  4. Multi-functional annular fairing for coupling launch abort motor to space vehicle

    NASA Technical Reports Server (NTRS)

    Camarda, Charles J. (Inventor); Scotti, Stephen J. (Inventor); Buning, Pieter G. (Inventor); Bauer, Steven X. S. (Inventor); Engelund, Walter C. (Inventor); Schuster, David M. (Inventor)

    2011-01-01

    An annular fairing having aerodynamic, thermal, structural and acoustic attributes couples a launch abort motor to a space vehicle having a payload of concern mounted on top of a rocket propulsion system. A first end of the annular fairing is fixedly attached to the launch abort motor while a second end of the annular fairing is attached in a releasable fashion to an aft region of the payload. The annular fairing increases in diameter between its first and second ends.

  5. Dislocation imaging for orthopyroxene using an atom-resolved scanning transmission electron microscopy.

    PubMed

    Kumamoto, Akihito; Kogure, Toshihiro; Raimbourg, Hugues; Ikuhara, Yuichi

    2014-11-01

    Dislocations, one-dimensional lattice defects, appear as a microscopic phenomenon while they are formed in silicate minerals by macroscopic dynamics of the earth crust such as shear stress. To understand ductile deformation mechanisms of silicates, atomic structures of the dislocations have been examined using transmission electron microscopy (TEM). Among them, it has been proposed that {100}<001> primary slip system of orthopyroxene (Opx) is dissociated into partial dislocations, and a stacking fault with the clinopyroxene (Cpx) structure is formed between the dislocations. This model, however, has not been determined completely due to the complex structures of silicates. Scanning transmission electron microscopy (STEM) has a potential to determine the structure of dislocations with single-atomic column sensitivity, particularly by using high-angle annular dark field (HAADF) and annular bright field (ABF) imaging with a probing aberration corrector.[1] Furthermore, successive analyses from light microscopy to atom-resolved STEM have been achieved by focused ion beam (FIB) sampling techniques.[2] In this study, we examined dislocation arrays at a low-angle grain boundary of ∼1° rotation about the b-axis in natural deformed Opx using a simultaneous acquisition of HAADF/ABF (JEM-ARM200F, JEOL) equipped with 100 mm2 silicon drift detector (SDD) for energy dispersive X-ray spectroscopy (EDS). Figure 1 shows averaged STEM images viewed along the b- axis of Opx extracted from repeating units. HAADF provides the cation-site arrangement, and ABF distinguishes the difference of slightly rotated SiO4 tetrahedron around the a- axis. This is useful to distinguish the change of stacking sequence between the partial dislocations. Two types of stacking faults with Cpx and protopyroxene (Ppx) structures were identified between three partial dislocations. Furthermore, Ca accumulation in M2 (Fe) site around the stacking faults was detected by STEM-EDS. Interestingly, Ca is

  6. DARK-FIELD ILLUMINATION SYSTEM

    DOEpatents

    Norgren, D.U.

    1962-07-24

    A means was developed for viewing objects against a dark background from a viewing point close to the light which illuminates the objects and under conditions where the back scattering of light by the objects is minimal. A broad light retro-directing member on the opposite side of the objects from the light returns direct light back towards the source while directing other light away from the viewing point. The viewing point is offset from the light and thus receives only light which is forwardly scattered by an object while returning towards the source. The object is seen, at its true location, against a dark background. The invention is particularly adapted for illuminating and viewing nuclear particle tracks in a liquid hydrogen bubble chamber through a single chamber window. (AEC)

  7. RESIDENCE TIME DISTRIBUTION OF FLUIDS IN STIRRED ANNULAR PHOTOREACTORS

    EPA Science Inventory

    When gases flow through an annular photoreactor at constant rate, some of the gas spends more or less than the average residence time in the reactor. This spread of residence time can have an important effect on the performance of the reactor. this study tested how the residence...

  8. An experimental investigation of straight and curved annular wall jets

    NASA Technical Reports Server (NTRS)

    Rodman, L. C.; Wood, N. J.; Roberts, L.

    1987-01-01

    Accurate turbulence measurements taken in wall jet flows are difficult to obtain, due to high intensity turbulence and problems in achieving two-dimensionality. The problem is compounded when streamwise curvature of the flow is introduced, since the jet entrainment and turbulence levels are greatly increased over the equivalent planar values. In this experiment, two-dimensional straight and curved incompressible wall jet flows are simulated by having a jet blow axially over a cylinder. Hot wire measurements and some Laser Doppler Velocimetry measurements are presented for straight and curved wall jet flows. The results for the straight wall showed good agreement between the annular flow data and the rectangular data taken by previous researchers. For the jets with streamwise curvature, there was agreement between the annular and corresponding rectangular jets for the flow region closest to the slot exit. An integral analysis was used as a simple technique to interpret the experimental results. Integral momentum calculations were performed for both straight and curved annular and two dimensional wall jets. The results of the calculation were used to identify transverse curvature parameters and to predict the values of those parameters which would delineate the region where the annular flow can satisfactorily simulate two dimensional flow.

  9. Thermal hydraulic analysis of annular fuel-based assemblies

    SciTech Connect

    Kyu Hyun Han; Soon Heung Chang

    2004-07-01

    Thermal hydraulic characteristics of thorium-based fuel assemblies loaded with annular seed pins have been analyzed using AMAP combined with MATRA, and compared with those of the existing thorium-based assemblies. MATRA and AMAP showed good agreements for the pressure drops at the internal subchannels. The pressure drop generally increased in the cases of the assemblies loaded with annular seed pins due to the larger wetted perimeter, but an exception existed. In the inner subchannels of the seed pins, mass fluxes were high due to the grid form losses in the outer subchannels. About 43% of the heat generated from the seed pin flowed into the inner subchannel and the rest into the outer subchannel, which implies the inner to outer wall heat flux ratio was approximately 1.2. The maximum temperatures of the annular seed pins were slightly above 500 deg. C. The MDNBRs of the assemblies loaded with annular seed pins were higher than those of the existing assemblies. Due to the fact that inter-channel mixing cannot occur in the inner subchannels, temperatures and enthalpies were higher in the inner subchannels. (authors)

  10. Digital controller design: Analysis of the annular suspension pointing system

    NASA Technical Reports Server (NTRS)

    1977-01-01

    The annular suspension and pointing system (ASPS) a payload auxiliary pointing device of the space shuttle is briefly described along with the function of the digital controller. The equations of motion of a simplified plan planar model of the ASPS are derived. Results of computer simulations are discussed.

  11. Subsonic annular wing theory with application to flow about nacelles

    NASA Technical Reports Server (NTRS)

    Mann, M. J.

    1974-01-01

    A method has recently been developed for calculating the flow over a subsonic nacelle at zero angle of attack. The method makes use of annular wing theory and boundary-layer theory and has shown good agreement with both experimental data and more complex theoretical solutions. The method permits variation of the mass flow by changing the size of a center body.

  12. Annular linear induction pump with an externally supported duct

    DOEpatents

    Craig, Edwin R.; Semken, Robert S.

    1979-01-01

    Several embodiments of an annular linear induction pump for pumping liquid metals are disclosed having the features of generally one pass flow of the liquid metal through the pump and an increased efficiency resulting from the use of thin duct walls to enclose the stator. The stator components of this pump are removable for repair and replacement.

  13. [Erythema annulare centrifugum-like psoriasis cum pustulatione].

    PubMed

    Albert, A; Hein, R; Ring, J; Jakob, T

    2007-09-01

    Erythema annulare centrifugum-type psoriasis with pustules represents a subtype of psoriasis pustulosa generalisata von Zumbusch. It presents with a typical morphology characterized by a lack of classical erythematosquamous skin lesions during its acute eruption phase. Diagnosis is usually established on the basis of clinical presentation and dermatopathology, which often shows a substrate typical for psoriasis, sometimes with spongiform pustules.

  14. Design curves for circular and annular duct silencers

    NASA Technical Reports Server (NTRS)

    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.

  15. Global regularity for MHD Sisko fluid in annular pipe

    NASA Astrophysics Data System (ADS)

    Rahman, S.; Hayat, T.; Ahmad, B.

    2016-08-01

    The flow of Sisko fluid in an annular pipe is considered. The governing nonlinear equation of an incompressible Sisko fluid is modelled. The purpose of present paper is to obtain the global classical solutions for unsteady flow of magnetohydrodynamic Sisko fluid in terms of the bounded mean oscillations norm. Uniqueness of solution is also verified.

  16. Three-dimensional analysis of Eu dopant atoms in Ca-α-SiAlON via through-focus HAADF-STEM imaging.

    PubMed

    Saito, Genki; Yamaki, Fuuta; Kunisada, Yuji; Sakaguchi, Norihito; Akiyama, Tomohiro

    2017-01-31

    Three-dimensional (3D) distributional analysis of individual dopant atoms in materials is important to development of optical, electronic, and magnetic materials. In this study, we adopted through-focus high-angle annular dark-field (HAADF) imaging for 3D distributional analysis of Eu dopant atoms in Ca-α-SiAlON phosphors. In this context, the effects of convergence semi-angle and Eu z-position on the HAADF image contrast were investigated. Multi-slice image simulation revealed that the contrast of the dopant site was sensitive to change of the defocus level. When the defocus level matched the depth position of a Eu atom, the contrast intensity was significantly increased. The large convergence semi-angle greatly increased the depth resolution because the electron beam tends spread instead of channeling along the atomic columns. Through-focus HAADF-STEM imaging was used to analyze the Eu atom distribution surrounding 10nm cubes with defocus steps of 0.68nm each. The contrast depth profile recorded with a narrow step width clearly analyzed the possible depth positions of Eu atoms. The radial distribution function obtained for the Eu dopants was analyzed using an atomic distribution model that was based on the assumption of random distribution. The result suggested that the Ca concentration did not affect the Eu distribution. The decreased fraction of neighboring Eu atoms along z-direction might be caused by the enhanced short-range Coulomb-like repulsive forces along the z-direction.

  17. Ultrafast laser parallel microdrilling using multiple annular beams generated by a spatial light modulator

    NASA Astrophysics Data System (ADS)

    Kuang, Zheng; Perrie, Walter; Edwardson, Stuart P.; Fearon, Eamonn; Dearden, Geoff

    2014-03-01

    Ultrafast laser parallel microdrilling using diffractive multiple annular beam patterns is demonstrated in this paper. The annular beam was generated by diffractive axicon computer generated holograms (CGHs) using a spatial light modulator. The diameter of the annular beam can be easily adjusted by varying the radius of the smallest ring in the axicon. Multiple annular beams with arbitrary arrangement and multiple annular beam arrays were generated by superimposing an axicon CGH onto a grating and lenses algorithm calculated multi-beam CGH and a binary Dammann grating CGH, respectively. Microholes were drilled through a 0.03 mm thick stainless steel foil using the multiple annular beams. By avoiding huge laser output attenuation and mechanical annular scanning, the processing is ˜200 times faster than the normal single beam processing.

  18. Grating-based X-ray phase contrast for biomedical imaging applications.

    PubMed

    Pfeiffer, Franz; Herzen, Julia; Willner, Marian; Chabior, Michael; Auweter, Sigrid; Reiser, Maximilian; Bamberg, Fabian

    2013-09-01

    In this review article we describe the development of grating-based X-ray phase-contrast imaging, with particular emphasis on potential biomedical applications of the technology. We review the basics of image formation in grating-based phase-contrast and dark-field radiography and present some exemplary multimodal radiography results obtained with laboratory X-ray sources. Furthermore, we discuss the theoretical concepts to extend grating-based multimodal radiography to quantitative transmission, phase-contrast, and dark-field scattering computed tomography.

  19. Direct imaging the upconversion nanocrystal core/shell structure at the subnanometer level: shell thickness dependence in upconverting optical properties.

    PubMed

    Zhang, Fan; Che, Renchao; Li, Xiaomin; Yao, Chi; Yang, Jianping; Shen, Dengke; Hu, Pan; Li, Wei; Zhao, Dongyuan

    2012-06-13

    Lanthanide-doped upconversion nanoparticles have shown considerable promise in solid-state lasers, three-dimensional flat-panel displays, and solar cells and especially biological labeling and imaging. It has been demonstrated extensively that the epitaxial coating of upconversion (UC) core crystals with a lattice-matched shell can passivate the core and enhance the overall upconversion emission intensity of the materials. However, there are few papers that report a precise link between the shell thickness of core/shell nanoparticles and their optical properties. This is mainly because rare earth fluoride upconversion core/shell structures have only been inferred from indirect measurements to date. Herein, a reproducible method to grow a hexagonal NaGdF(4) shell on NaYF(4):Yb,Er nanocrystals with monolayer control thickness is demonstrated for the first time. On the basis of the cryo-transmission electron microscopy, rigorous electron energy loss spectroscopy, and high-angle annular dark-field investigations on the core/shell structure under a low operation temperature (96 K), direct imaging the NaYF(4):Yb,Er@NaGdF(4) nanocrystal core/shell structure at the subnanometer level was realized for the first time. Furthermore, a strong linear link between the NaGdF(4) shell thickness and the optical response of the hexagonal NaYF(4):Yb,Er@NaGdF(4) core/shell nanocrystals has been established. During the epitaxial growth of the NaGdF(4) shell layer by layer, surface defects of the nanocrystals can be gradually passivated by the homogeneous shell deposition process, which results in the obvious enhancement in overall UC emission intensity and lifetime and is more resistant to quenching by water molecules.

  20. Dual annular rotating "windowed" nuclear reflector reactor control system

    DOEpatents

    Jacox, Michael G.; Drexler, Robert L.; Hunt, Robert N. M.; Lake, James A.

    1994-01-01

    A nuclear reactor control system is provided in a nuclear reactor having a core operating in the fast neutron energy spectrum where criticality control is achieved by neutron leakage. The control system includes dual annular, rotatable reflector rings. There are two reflector rings: an inner reflector ring and an outer reflector ring. The reflectors are concentrically assembled, surround the reactor core, and each reflector ring includes a plurality of openings. The openings in each ring are capable of being aligned or non-aligned with each other. Independent driving means for each of the annular reflector rings is provided so that reactor criticality can be initiated and controlled by rotation of either reflector ring such that the extent of alignment of the openings in each ring controls the reflection of neutrons from the core.

  1. Annular fuel and air co-flow premixer

    DOEpatents

    Stevenson, Christian Xavier; Melton, Patrick Benedict; York, William David

    2013-10-15

    Disclosed is a premixer for a combustor including an annular outer shell and an annular inner shell. The inner shell defines an inner flow channel inside of the inner shell and is located to define an outer flow channel between the outer shell and the inner shell. A fuel discharge annulus is located between the outer flow channel and the inner flow channel and is configured to inject a fuel flow into a mixing area in a direction substantially parallel to an outer airflow through the outer flow channel and an inner flow through the inner flow channel. Further disclosed are a combustor including a plurality of premixers and a method of premixing air and fuel in a combustor.

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

    PubMed

    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.

  3. Droplet deposition and momentum transfer in annular flow

    SciTech Connect

    Fore, L.B.; Dukler, A.E.

    1995-09-01

    Entrainment and deposition in gas-liquid annular upflow are known to account for as much as 20% of the pressure gradient, through droplet accelerations in the core region. Momentum is transferred from the core when droplets decelerate upon impact with the liquid film. It is usually assumed that all of this momentum is transferred to the film, essentially driving the film upward in conjunction with interfacial friction. New data, obtained for annular gas-liquid upflow in a 5.08-cm-ID tube, are used in a momentum balance analysis to determine the mechanism of momentum transfer from depositing droplets. Measurements include the liquid film thickness, wall shear stress, pressure gradient, entrained liquid fraction, droplet deposition rate, droplet centerline axial velocity, and mass-average drop size for two gas-liquid systems. This analysis supports the idea that large droplets displace the film locally and decelerate primarily at the wall, effectively transferring negligible momentum to the liquid film.

  4. Thermo-Elastic Finite Element Analyses of Annular Nuclear Fuels

    NASA Astrophysics Data System (ADS)

    Kwon, Y. D.; Kwon, S. B.; Rho, K. T.; Kim, M. S.; Song, H. J.

    In this study, we tried to examine the pros and cons of the annular type of fuel concerning mainly with the temperatures and stresses of pellet and cladding. The inner and outer gaps between pellet and cladding may play an important role on the temperature distribution and stress distribution of fuel system. Thus, we tested several inner and outer gap cases, and we evaluated the effect of gaps on fuel systems. We conducted thermo-elastic-plastic-creep analyses using an in-house thermo-elastic-plastic-creep finite element program that adopted the 'effective-stress-function' algorithm. Most analyses were conducted until the gaps disappeared; however, certain analyses lasted for 1582 days, after which the fuels were replaced. Further study on the optimal gaps sizes for annular nuclear fuel systems is still required.

  5. Higher order annular Gaussian laser beam propagation in free space

    NASA Astrophysics Data System (ADS)

    Eyyuboglu, Halil T.; Yenice, Yusuf E.; Baykal, Yahya K.

    2006-03-01

    Propagation of higher order annular Gaussian (HOAG) laser beams in free space is examined. HOAG beams are defined as the difference of two Hermite-Gaussian (HG) beams; thus, they can be produced by subtracting a smaller beam from a larger beam, that are cocentered and both possess HG mode field distributions. Such beams can be considered as a generalization of the well-known annular Gaussian beams. We formulate the source and receiver plane characteristics and kurtosis parameter of HOAG beams propagating in free space and evaluate them numerically. In comparison to HG beams, HOAG beams have a broader beam size with outer lobes of kidney shape. The amount of received power within the same receiver aperture size, that is, power in bucket, is generally lower for higher order beams. The convergence of the kurtosis parameter to an asymptotic value for higher order beams takes much longer propagation distances compared to zero-order beams.

  6. High Thrust-to-Power Annular Engine Technology

    NASA Technical Reports Server (NTRS)

    Patterson, Michael; Thomas, Robert; Crofton, Mark; Young, Jason A.; Foster, John E.

    2015-01-01

    Gridded ion engines have the highest efficiency and total impulse of any mature electric propulsion technology, and have been successfully implemented for primary propulsion in both geocentric and heliocentric environments with excellent ground-in-space correlation of performance. However, they have not been optimized to maximize thrust-to-power, an important parameter for Earth orbit transfer applications. This publication discusses technology development work intended to maximize this parameter. These activities include investigating the capabilities of a non-conventional design approach, the annular engine, which has the potential of exceeding the thrust-to-power of other EP technologies. This publication discusses the status of this work, including the fabrication and initial tests of a large-area annular engine. This work is being conducted in collaboration among NASA Glenn Research Center, The Aerospace Corporation, and the University of Michigan.

  7. High Thrust-to-Power Annular Engine Technology

    NASA Technical Reports Server (NTRS)

    Patterson, Michael J.; Thomas, Robert E.; Crofton, Mark W.; Young, Jason A.; Foster, John E.

    2015-01-01

    Gridded ion engines have the highest efficiency and total impulse of any mature electric propulsion technology, and have been successfully implemented for primary propulsion in both geocentric and heliocentric environments with excellent ground/in-space correlation of performance. However, they have not been optimized to maximize thrust-to-power, an important parameter for Earth orbit transfer applications. This publication discusses technology development work intended to maximize this parameter. These activities include investigating the capabilities of a non-conventional design approach, the annular engine, which has the potential of exceeding the thrust-to-power of other EP technologies. This publication discusses the status of this work, including the fabrication and initial tests of a large-area annular engine. This work is being conducted in collaboration among NASA Glenn Research Center, The Aerospace Corporation, and the University of Michigan.

  8. Vortex dynamics in an annular Josephson ratchet ladder

    NASA Astrophysics Data System (ADS)

    Lee, Ki Ho

    2016-11-01

    We present numerically the motion of vortices placed in an annular Josephson ladder which has a periodic ratchet potential along the annular direction. The ratchet characteristics are provided by assigning both alternate critical currents and alternate plaquette areas. The vortices are subject to an external current applied uniformly from each superconducting grain in the inner ring to each grain in the outer ring. The current-voltage (I-V) curves show asymmetric features because of the spatially broken symmetry of the potential. When an alternating current is added to the external current, Shapiro steps appear in the I-V curves, showing asymmetric values of the step widths and on-set currents. For a certain range of the alternating currents, vortices rotate to the easy direction, even at zero driving current, that corresponds to the direction away from the steep slope and toward the gentle slope of the ratchet potential.

  9. Simple analysis and design of annular ring microstrip antennas

    NASA Astrophysics Data System (ADS)

    El-Khamy, S. E.; El-Awadi, R. M.; El-Sharrawy, E.-B. A.

    1986-06-01

    A simple analysis of thin annular-ring microstrip antennas (AR-MSA), along with a design technique that yields the optimum ring dimensions which maximizes the radiation efficiency and the bandwidth, is presented in this paper. Using the cavity model, exact closed form solutions for the radiation fields are derived. The antenna fields distribution, resonance dimensions, radiation patterns, directivity, radiation conductance, quality factor and bandwidth are investigated for the different TMnm modes. AR-MSAs operated at the high order TMn2 modes are found to have better radiation properties and broader bandwidths than the corresponding disk-MSAs. A design table for the optimum ring dimensions for different types of the dielectric substrate material is also given in the paper.

  10. Axisymmetric buckling of laminated thick annular spherical cap

    NASA Astrophysics Data System (ADS)

    Dumir, P. C.; Dube, G. P.; Mallick, A.

    2005-03-01

    Axisymmetric buckling analysis is presented for moderately thick laminated shallow annular spherical cap under transverse load. Buckling under central ring load and uniformly distributed transverse load, applied statically or as a step function load is considered. The central circular opening is either free or plugged by a rigid central mass or reinforced by a rigid ring. Annular spherical caps have been analysed for clamped and simple supports with movable and immovable inplane edge conditions. The governing equations of the Marguerre-type, first order shear deformation shallow shell theory (FSDT), formulated in terms of transverse deflection w, the rotation ψ of the normal to the midsurface and the stress function Φ, are solved by the orthogonal point collocation method. Typical numerical results for static and dynamic buckling loads for FSDT are compared with the classical lamination theory and the dependence of the effect of the shear deformation on the thickness parameter for various boundary conditions is investigated.

  11. Analysis of Enriched Uranyl Nitrate in Nested Annular Tank Array

    SciTech Connect

    John D. Bess; James D. Cleaver

    2009-06-01

    Two series of experiments were performed at the Rocky Flats Critical Mass Laboratory during the 1980s using highly enriched (93%) uranyl nitrate solution in annular tanks. [1, 2] Tanks were of typical sizes found in nuclear production plants. Experiments looked at tanks of varying radii in a co-located set of nested tanks, a 1 by 2 array, and a 1 by 3 array. The co-located set of tanks had been analyzed previously [3] as a benchmark for inclusion within the International Handbook of Evaluated Criticality Safety Benchmark Experiments. [4] The current study represents the benchmark analysis of the 1 by 3 array of a series of nested annular tanks. Of the seventeen configurations performed in this set of experiments, twelve were evaluated and nine were judged as acceptable benchmarks.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  14. Annular Momentum Control Device (AMCD). Volume 1: Laboratory model development

    NASA Technical Reports Server (NTRS)

    1975-01-01

    The annular momentum control device (AMCD) a thin hoop-like wheel with neither shaft nor spokes is described. The wheel floats in a magnetic field and can be rotated by a segmented motor. Potential advantages of such a wheel are low weight, configuration flexibility, a wheel that stiffens with increased speed, vibration isolation, and increased reliability. The analysis, design, fabrication, and testing is described of the laboratory model of the AMCD.

  15. System design of the annular suspension and pointing system /ASPS/

    NASA Technical Reports Server (NTRS)

    Cunningham, D. C.; Gismondi, T. P.; Wilson, G. W.

    1978-01-01

    This paper presents the control system design for the Annular Suspension and Pointing System. Actuator sizing and configuration of the system are explained, and the control laws developed for linearizing and compensating the magnetic bearings, roll induction motor and gimbal torquers are given. Decoupling, feedforward and error compensation for the vernier and gimbal controllers is developed. The algorithm for computing the strapdown attitude reference is derived, and the allowable sampling rates, time delays and quantization of control signals are specified.

  16. Closed cycle annular-return gas flow electrical discharge laser

    SciTech Connect

    Bletzinger, P.; Garscadden, A.; Hasinger, S.H.; Olson, R.A.; Sarka, B.

    1981-06-16

    A closed cycle, high repetition pulsed laser is disclosed that has a laser flow channel with an annular flow return surrounding the laser flow channel. Ultra high vacuum components and low out-gassing materials are used in the device. An externally driven axial flow fan is used for gas recirculation. A thyratron-switched lowinductance energy storage capacitor is used to provide a transverse discharge between profiled electrodes in the laser cavity.

  17. The influence of annular seal clearance to the critical speed of the multistage pump

    NASA Astrophysics Data System (ADS)

    Wang, J.; Shen, H. P.; Y Ye, X.; Hu, J. N.; Feng, Y. N.

    2013-12-01

    In the multistage pump of high head, pressure difference in two ends of annular seal clearance and rotor eccentric would produce the sealing fluid force, the effect of which can be expressed by a damping and stiffness coefficient. It has a great influence on the critical speed of the rotor system. In order to research the influence of the annular seal to the rotor system, this paper used CFD method to conduct the numerical simulation for the flow field of annular seal clearance. The radial and tangential forces were obtained to calculate the annular dynamic coefficients. Also dynamic coefficient were obtained by Matlab. The rotor system was modeled using ANSYS finite software and the critical speed with and without annular seal clearance were calculated. The result shows: annular seal's fluid field is under the comprehensive effect of pressure difference and rotor entrainment. Due to the huge pressure difference in front annular seal, fluid flows under pressure difference; the low pressure difference results in the more obvious effect on the clearance field in back annular seal. The first order critical speed increases greatly with the annular seal clearance; while the average growth rate of the second order critical speed is only 3.2%; the third and fourth critical speed decreases little. Based on the above result, the annular seal has great influence to the first order speed, while has little influence on the rest.

  18. Standing wave acoustic levitation on an annular plate

    NASA Astrophysics Data System (ADS)

    Kandemir, Mehmet Hakan; Çalışkan, Mehmet

    2016-11-01

    In standing wave acoustic levitation technique, a standing wave is formed between a source and a reflector. Particles can be attracted towards pressure nodes in standing waves owing to a spring action through which particles can be suspended in air. This operation can be performed on continuous structures as well as in several numbers of axes. In this study an annular acoustic levitation arrangement is introduced. Design features of the arrangement are discussed in detail. Bending modes of the annular plate, known as the most efficient sound generation mechanism in such structures, are focused on. Several types of bending modes of the plate are simulated and evaluated by computer simulations. Waveguides are designed to amplify waves coming from sources of excitation, that are, transducers. With the right positioning of the reflector plate, standing waves are formed in the space between the annular vibrating plate and the reflector plate. Radiation forces are also predicted. It is demonstrated that small particles can be suspended in air at pressure nodes of the standing wave corresponding to a particular bending mode.

  19. Annular tautomerism: experimental observations and quantum mechanics calculations

    NASA Astrophysics Data System (ADS)

    Cruz-Cabeza, Aurora J.; Schreyer, Adrian; Pitt, William R.

    2010-06-01

    The use of MP2 level quantum mechanical (QM) calculations on isolated heteroaromatic ring systems for the prediction of the tautomeric propensities of whole molecules in a crystalline environment was examined. A Polarisable Continuum Model was used in the calculations to account for environment effects on the tautomeric relative stabilities. The calculated relative energies of tautomers were compared to relative abundances within the Cambridge Structural Database (CSD) and the Protein Data Bank (PDB). The work was focussed on 84 annular tautomeric forms of 34 common ring systems. Good agreement was found between the calculations and the experimental data even if the quantity of these data was limited in many cases. The QM results were compared to those produced by much faster semiempirical calculations. In a search for other sources of the useful experimental data, the relative numbers of known compounds in which prototropic positions were often substituted by heavy atoms were also analysed. A scheme which groups all annular tautomeric transformations into 10 classes was developed. The scheme was designed to encompass a comprehensive set of known and theoretically possible tautomeric ring systems generated as part of a previous study. General trends across analogous ring systems were detected as a result. The calculations and statistics collected on crystallographic data as well as the general trends observed should be useful for the better modelling of annular tautomerism in the applications such as computer-aided drug design, small molecule crystal structure prediction, the naming of compounds and the interpretation of protein—small molecule crystal structures.

  20. Free vortex theory for efficiency calculations from annular cascade data

    SciTech Connect

    Main, A.J.; Oldfield, M.L.G.; Lock, G.D.; Jones, T.V.

    1997-04-01

    This paper describes a new three-dimensional theory to calculate the efficiency or loss of nozzle guide vane annular cascades from experimental area traverse measurements of the compressible downstream flow. To calculate such an efficiency, it is necessary to mix out the measured flow computationally to either a uniform state or one that is a function of radius only. When this is done by conserving momentum, mass, and energy flow, there is a remaining degree of freedom in that the radial distribution of circumferential velocity can be chosen. This extra freedom does not arise in two-dimensional cascades. The new method mixes the flow out to a free (i.e., irrotational) vortex. This is preferred to existing methods in that it gives a physically realistic flow and also provides a unique, lossless, isentropic reference flow. The annular cascade efficiency is then uniquely defined as the ratio of the mixed-out experimental kinetic energy flux to the ideal isentropic kinetic energy flux at the same mean radius static pressure. The mathematical derivation of this method is presented. This new theory has been used to process data obtained from a large, transonic, annular cascade in a blowdown tunnel. A four-hole pyramid probe, mounted on a computer-controlled traverse, has been used to map the passage flowfield downstream of the nozzle guide vanes. Losses calculated by the new method are compared with those calculated from the same data using earlier analysis methods.

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

    SciTech Connect

    Lopes, J C.B.; Dukler, A E

    1985-10-01

    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.

  2. The annular flow electrothermal ramjet. M.S. Thesis

    NASA Technical Reports Server (NTRS)

    Shaw, B. D.

    1984-01-01

    The annular flow, electrothermal, plug ramjet is examined as a possible means of achieving rapid projectile acceleration to velocities for such applications as direct launch of spacebound payloads. The performance of this ramjet operating with hydrogen propellant is examined for cases where this working fluid is treated: (1) as a perfect gas, and (2) as a gas that is allowed to dissociate and ionize and then recombine with finite reaction rates in the nozzle. Performance results for these cases are compared to the performance of a conventional ramjet operating with perfect gas hydrogen propellant. The performance of the conventional ramjet is superior to that of the annular flow, electrothermal ramjet. However, it is argued that the mechanical complexities associated with conventional ramjet operation are difficult to attain, and for this reason the annular flow, electrothermal ramjet is more desirable as a launch system. Models are presented which describe both electrothermal plug ramjet and conventional ramjet operation, and it is shown that for a given flight velocity there is a rate of heat addition per unit propellant mass for which ramjet operation is optimized.

  3. Non-scanning measurement of convex and concave curvature with an annular array

    NASA Astrophysics Data System (ADS)

    Lenz, Michael; Kühnicke, Elfgard

    2012-05-01

    The paper describes a novel ultrasonic method for measuring local object curvature radii without scanning. For the measurements, an ultrasonic annular array is used, where the phase and amplitude differences on the different receivers are used to determine the object curvature radius and its distance from the transducer simultaneously. The method aims at measurements of spherical or oval inclusions in fluids and solids in general, and of the curvature radius of eye lens and retina in particular. It is intended to work as a supplement to conventional imaging applications. To verify the measurement method, theoretical and experimental results with steel spheres as reflectors are presented. After measuring and taking into account the acoustically effective size of the single transducer elements, good agreement between measurements and simulations could be achieved.

  4. Annular force based variable curvature mirror aiming to realize non-moving element optical zooming

    NASA Astrophysics Data System (ADS)

    Zhao, Hui; Xie, Xiaopeng; Wei, Jingxuan; Ren, Guorui; Pang, Zhihai; Xu, Liang

    2015-10-01

    Recently, a new kind of optical zooming technique in which no moving elements are involved has been paid much attention. The elimination of moving elements makes optical zooming suitable for applications which has exacting requirements in space, power cost and system stability. The mobile phone and the space-borne camera are two typical examples. The key to realize non-moving elements optical zooming lies in the introduction of variable curvature mirror (VCM) whose radius of curvature could be changed dynamically. When VCM is about to be used to implement optical zoom imaging, two characteristics should be ensured. First, VCM has to provide large enough saggitus variation in order to obtain a big magnification ratio. Second, after the radius of curvature has been changed, the corresponding surface figure accuracy should still be maintained superior to a threshold level to make the high quality imaging possible. In this manuscript, based on the elasticity theory, the physical model of the annular force based variable curvature mirror is established and numerically analyzed. The results demonstrate that when the annular force is applied at the half-the-aperture position, the actuation force is reduced and a smaller actuation force is required to generate the saggitus variation and thus the maintenance of surface figure accuracy becomes easier during the variation of radius of curvature. Besides that, a prototype VCM, whose diameter and thickness are 100mm and 3mm respectively, have been fabricated and the maximum saggitus variation that could be obtained approaches more than 30 wavelengths. At the same time, the degradation of surface figure accuracy is weakly correlated to the curvature radius variation. Keywords: optical zooming; variable curvature mirror; surface figure accuracy; saggitus;

  5. Lumped element modeling of air-coupled capacitive micromachined ultrasonic transducers with annular cell geometry.

    PubMed

    Na, Shuai; Wong, Lawrence L P; Chen, Albert I H; Li, Zhenhao; Macecek, Mirek; Yeow, John T W

    2017-04-01

    Air-coupled capacitive micromachined ultrasonic transducers (CMUTs) based on annular cell geometry have recently been reported. Finite element analysis and experimental studies have demonstrated their significant improvement in transmit efficiency compared with the conventional circular-cell CMUTs. Extending the previous work, this paper proposed a lumped element model of annular-cell CMUTs. Explicit expressions of the resonance frequency, modal vector, and static displacement of a clamped annular plate under uniform pressure were first derived based on the plate theory and curve fitting method. The lumped model of an annular CMUT cell was then developed by adopting the average displacement as the spatial variable. Using the proposed model, the ratio of average-to-maximum displacement was derived to be 8/15. Experimental and simulation studies on a fabricated annular CMUT cell verified the effectiveness of the lumped model. The proposed model provides an effective and efficient way to analyze and design air-coupled annular-cell CMUTs.

  6. Imaging study on acupuncture points

    NASA Astrophysics Data System (ADS)

    Yan, X. H.; Zhang, X. Y.; Liu, C. L.; Dang, R. S.; Ando, M.; Sugiyama, H.; Chen, H. S.; Ding, G. H.

    2009-09-01

    The topographic structures of acupuncture points were investigated by using the synchrotron radiation based Dark Field Image (DFI) method. Four following acupuncture points were studied: Sanyinjiao, Neiguan, Zusanli and Tianshu. We have found that at acupuncture point regions there exists the accumulation of micro-vessels. The images taken in the surrounding tissue out of the acupuncture points do not show such kind of structure. It is the first time to reveal directly the specific structure of acupuncture points by X-ray imaging.

  7. Annular pancreas complicated by carcinoma of the bile duct: diagnosis by MR cholangiopancreatography and endoscopic ultrasonography.

    PubMed

    Yamaguchi, Y; Sugiyama, M; Sato, Y; Mine, Y; Yamato, T; Ishida, H; Takahashi, S

    2003-01-01

    It has been reported that annular pancreas should be evaluated for coexisting malignant tumors. However, no cases have been reported in which magnetic resonance cholangiopancreatography and endoscopic ultrasonography clearly demonstrated an annular pancreas complicated by bile duct carcinoma. We present a case that emphasizes the importance of magnetic resonance cholangiopancreatography and endoscopic ultrasonography in directly confirming a diagnosis of annular pancreas complicated by bile duct carcinoma.

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

    PubMed

    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.

  9. Links between granuloma annulare, necrobiosis lipoidica diabeticorum and childhood diabetes: a matter of time?

    PubMed

    Davison, James E; Davies, Alison; Moss, Celia; Kirk, Jeremy M W; Taibjee, Saleem M; Agwu, J Chizo

    2010-01-01

    Diabetes mellitus is associated with a range of dermatologic presentations, including granuloma annulare and necrobiosis lipoidica diabeticorum. Granuloma annulare occurs earlier than necrobiosis lipoidica diabeticorum and the association with diabetes mellitus is much weaker. We describe two children with diabetes who both developed granuloma annulare and later, necrobiosis lipoidica diabeticorum. We postulate that the early onset and transient nature of granuloma annulare, compared with the later onset and persistence of necrobiosis lipoidica diabeticorum, might account for the different apparent rates of association with diabetes mellitus.

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

    DOEpatents

    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.

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

    DOEpatents

    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.

  12. Studies on Normal and Microgravity Annular Two Phase Flows

    NASA Technical Reports Server (NTRS)

    Balakotaiah, V.; Jayawardena, S. S.; Nguyen, L. T.

    1999-01-01

    Two-phase gas-liquid flows occur in a wide variety of situations. In addition to normal gravity applications, such flows may occur in space operations such as active thermal control systems, power cycles, and storage and transfer of cryogenic fluids. Various flow patterns exhibiting characteristic spatial and temporal distribution of the two phases are observed in two-phase flows. The magnitude and orientation of gravity with respect to the flow has a strong impact on the flow patterns observed and on their boundaries. The identification of the flow pattern of a flow is somewhat subjective. The same two-phase flow (especially near a flow pattern transition boundary) may be categorized differently by different researchers. Two-phase flow patterns are somewhat simplified in microgravity, where only three flow patterns (bubble, slug and annular) have been observed. Annular flow is obtained for a wide range of gas and liquid flow rates, and it is expected to occur in many situations under microgravity conditions. Slug flow needs to be avoided, because vibrations caused by slugs result in unwanted accelerations. Therefore, it is important to be able to accurately predict the flow pattern which exists under given operating conditions. It is known that the wavy liquid film in annular flow has a profound influence on the transfer of momentum and heat between the phases. Thus, an understanding of the characteristics of the wavy film is essential for developing accurate correlations. In this work, we review our recent results on flow pattern transitions and wavy films in microgravity.

  13. Spatiotemporal structure of a millimetric annular dielectric barrier discharge plasma actuator

    NASA Astrophysics Data System (ADS)

    Humble, R. A.; Craig, S. A.; Vadyak, J.; McClure, P. D.; Hofferth, J. W.; Saric, W. S.

    2013-01-01

    The spatiotemporal structure of a millimetric annular dielectric barrier discharge plasma actuator is investigated using a photomultiplier tube, a high-sensitivity camera, particle image velocimetry, and electrohydrodynamics simulations. Plasma actuators have typically demonstrated their utility in flow separation control, but on a millimetric scale they have also shown to be promising in the control of crossflow instabilities in crossflow-dominated laminar-turbulent boundary-layer transition. In view of the subtleties associated with creating an initial disturbance to excite subcritical wavelengths, it is desirable to characterize the local plasma discharge structure, body force organization, and induced velocity field in detail. The results show that, similar to their linear centimetric counterpart, the plasma discharge has a highly dynamic and somewhat organized spatiotemporal structure. Under quiescent flow conditions, the actuator induces a velocity field that consists of two counter-rotating vortices, accompanied by a wall-normal synthetic jet region, which in three-dimensions describes a toroidal vortex around the aperture's periphery. The surprising result, however, is that these vortices rotate in the opposite direction to vortices generated by similar centimetric annular designs. Three-dimensional electrohydrodynamics simulations correctly reproduce this behavior. Because the body force organization may be qualitatively perceived as being the axisymmetric counterpart of the more classical linear actuator, this flow reversal is thought to be due to the actuator scale. When an array of millimetric actuators is considered in close proximity, an interaction takes place between the vortices created from each actuator and those of neighboring actuators, resulting in a significant reduction in vortex size compared with the single aperture case, accompanied by an increase in the maximum induced flow velocity magnitude.

  14. Structure Limits for a 30mm Annular Piston.

    DTIC Science & Technology

    1988-05-01

    Properties ," BRL Report #1359, Mar 1971. 4. Republic Steel Corp., "Precipitation Hardenable Stainless Steel, PH13 -8MO, 15-5 PH, PH15-7MO, 17-4 PH, 17...u * 3 *1938 - Serving the Army for Fifty Years - 1988 STRUCTURE LIMITS FOR A *30-MMA ANN.,\\ULAR PISTON CRIS WATSON DTIC MAY 1988 JUN 14 8 APPROVED...NAME OF FUNDING/SPONSORING 8 b OFFICE SYMBOL 9 PROCUREMENT INSTRUMENT IDENTIFICATION NUMBER ORGANIZATIONj (If applicable) r-c ADDRESS (City, State

  15. Cylindrical plasmas generated by an annular beam of ultraviolet light

    SciTech Connect

    Thomas, D. M.; Allen, J. E.

    2015-07-15

    We investigate a cylindrical plasma system with ionization, by an annular beam of ultraviolet light, taking place only in the cylinder's outer region. In the steady state, both the outer and inner regions contain a plasma, with that in the inner region being uniform and field-free. At the interface between the two regions, there is an infinitesimal jump in ion density, the magnitude approaching zero in the quasi-neutral (λ{sub D} → 0) limit. The system offers the possibility of producing a uniform stationary plasma in the laboratory, hitherto obtained only with thermally produced alkali plasmas.

  16. Detonation Initiation by Annular Jets and Shock Waves

    DTIC Science & Technology

    2007-11-02

    11,12,13,14,15,16,17,18, 19,20,21,22 to better understand the shock implosion process. The current interest in air-breathing pulse detonation engines ( PDEs ) has led...This technology has yet to be realized and, as a result, current PDEs use initiator tubes sensitized with oxygen 23 or detonate more sensitive mixtures... Detonation Initiation by Annular Jets and Shock Waves Final Report for Award ONR N00014-03 -0931 Joseph E. Shepherd Aeronautics California Institute

  17. Histiocytoid Sweet's syndrome presenting with annular erythematous plaques*

    PubMed Central

    Marcarini, Renata; de Araujo, Raquel Nardelli; Nóbrega, Monisa Martins; Medeiros, Karina Bittencourt; Gripp, Alexandre Carlos; Maceira, Juan Manuel Piñeiro

    2016-01-01

    Histiocytoid Sweet's Syndrome is a rare inflammatory disease described in 2005 as a variant of the classical Sweet's Syndrome (SS). Histopathologically, the dermal inflammatory infiltrate is composed mainly of mononuclear cells that have a histiocytic appearance and represent immature myeloid cells. We describe a case of Histiocytoid Sweet's Syndrome in an 18-year-old man. Although this patient had clinical manifestations compatible with SS, the cutaneous lesions consisted of erythematous annular plaques, which are not typical for this entity and have not been described in histiocytic form so far. The histiocytic subtype was confirmed by histopathological analysis that showed positivity for myeloperoxidase in multiple cells with histiocytic appearance. PMID:28300927

  18. Dynamically adjustable annular laser trapping based on axicons

    SciTech Connect

    Shao, Bing; Esener, Sadik C.; Nascimento, Jaclyn M.; Botvinick, Elliot L.; Berns, Michael W

    2006-09-01

    To study the chemotactic response of sperm to an egg and to characterize sperm motility, an annular laser trap based on axicons is designed, simulated with the ray-tracing tool, and implemented. The diameter of the trapping ring can be adjusted dynamically for a range of over 400 {mu}m by simply translating one axicon along the optical axis. Trapping experiments with microspheres and dog sperm demonstrate the feasibility of the system,and the power requirement agrees with theoretical expectation. This new type of laser trapping could provide a prototype of a parallel, objective, and quantitative tool for animal fertility and biotropism study.

  19. Laser window with annular grooves for thermal isolation

    DOEpatents

    Warner, B.E.; Horton, J.A.; Alger, T.W.

    1983-07-13

    A laser window or other optical element which is thermally loaded, heats up and causes optical distortions because of temperature gradients between the center and the edge. A number of annular grooves, one to three or more, are formed in the element between a central portion and edge portion, producing a web portion which concentrates the thermal gradient and thermally isolates the central portion from the edge portion, producing a uniform temperature profile across the central portion and therefore reduce the optical distortions. The grooves are narrow and closely spaced with respect to the thickness of the element, and successive grooves are formed from alternate sides of the element.

  20. New fluxon resonant mechanism in annular Josephson tunnel structures.

    PubMed

    Nappi, C; Lisitskiy, M P; Rotoli, G; Cristiano, R; Barone, A

    2004-10-29

    A novel dynamical state has been observed in the dynamics of a perturbed sine-Gordon system. This resonant state has been experimentally observed as a singularity in the dc current-voltage characteristic of an annular Josephson tunnel junction, excited in the presence of a magnetic field. In this respect it can be assimilated to self-resonances known as Fiske steps. Differently from these, however, we demonstrate, on the basis of numerical simulations, that its detailed dynamics involves rotating fluxon pairs, a mechanism associated, so far, to self-resonances known as zero-field steps. This occurs because the size of nonlinear excitations is comparable with that of the system.

  1. A study of unsteady flow induced by annular cascade

    SciTech Connect

    Takama, N.; Yoshiki, H.; Nishimura, K.; Sumiyoshi, K.

    1999-07-01

    The authors have experimentally studied phenomena of unsteady flow induced by annular cascade. The test apparatus consists of a swirl generator connected to a suction-type wind tunnel. The swirl generator duplicates variable inlet guide vanes (VIGV). The authors measured distributions of velocity flow by a hot wire anemometer and a three-hole Pilot tube, and pressure by semiconductor transducers. Results are: (1) the Strouhal number is independent of Reynolds number under each experimental condition; (2) the velocity wave propagates from pressure side of a vane to suction side of a neighboring vane; and (3) the setting angle of VIGV has effects on a fundamental frequency.

  2. Preparative-scale proteins seperations by continuous annular chromatography

    SciTech Connect

    Bloomingburg, G.F.; Bauer, J.S.; Carta, G.; Byers, C.H. . Dept. of Chemical Engineering; Oak Ridge National Lab., TN )

    1989-01-01

    The use of continuous annular chromatography (CAC) for the separation of protein mixtures is studied in a preparative-scale CAC unit. S-Sepharose, a strong-acid porous cation exchange resin is used as the separation medium mixtures of albumin, hemoglobin, and cytochrome-C are used as a model separation system. Equilibrium and mass transfer parameter are developed for this system on the basis of fixed-bed chromatograph experiments. A mathematical model is then successfully used in conjunction with these parameters to simulate the performance of the CAC separations. 11 refs., 11 figs., 3 tabs.

  3. Asymmetric Separation and Perturbation Sensitivity in an Annular Diffuser

    NASA Astrophysics Data System (ADS)

    Coffman, Jesse; Morris, Scott; Jemcov, Aleksander; Cameron, Joshua

    2013-11-01

    When an annular diffuser stalls, the separation can take many forms. Experiments show that one type of separation appears to be asymmetric and periodic. This asymmetry appears to be influenced by upstream and downstream components and inlet flow conditions. By understanding the changes effected at the exit of the diffuser by the inlet perturbations, the diffuser performance can be more accurately predicted within a system. This work aims to understand the influence of velocity perturbations at the inlet of the diffuser on the overall duct performance. This is done by application of the Euler equations and a RANS simulation for various circumferential wavenumbers.

  4. Annular Suspension and Pointing System (ASPS) magnetic rotary joint

    NASA Technical Reports Server (NTRS)

    Smith, W. E.; Quach, W.; Thomas, W.

    1993-01-01

    The Annular Suspension and Pointing System (ASPS) is a prototype of flight hardware for a high-accuracy space payload pointing mount. The long term project objective is to perform modifications and implement improvements to the existing ASPS in hopes of recommission. Also, new applications will be investigated for this technology. This report will focus on the first aspect of this overall goal, to establish operation of a single bearing station. Presented is an overview of the system history and bearing operation followed by the processes, results, and status of the single bearing study.

  5. Identification of dynamic coefficients of annular turbulent seals

    NASA Technical Reports Server (NTRS)

    Nordmann, R.; Massmann, H.

    1984-01-01

    An identification procedure to determine dynamic coefficients of annular turbulent seals in turbopumps is presented. Measurements were carried out at a built test rig with two symmetrical arranged seals. A rigid rotating shaft is surrounded by an elastically supported housing, which is excited by impact forces. The relative radial motion between the rotating parts and the housing, respectively between the seal surfaces, is measured by displacement pick-ups and from the time signals complex frequency response functions can be calculated. Finally an analytical model, depending on the seal parameters, is fitted to the measured data, to find the dynamic coefficients.

  6. Dynamically adjustable annular laser trapping based on axicons

    NASA Astrophysics Data System (ADS)

    Shao, Bing; Esener, Sadik C.; Nascimento, Jaclyn M.; Botvinick, Elliot L.; Berns, Michael W.

    2006-09-01

    To study the chemotactic response of sperm to an egg and to characterize sperm motility, an annular laser trap based on axicons is designed, simulated with the ray-tracing tool, and implemented. The diameter of the trapping ring can be adjusted dynamically for a range of over 400 μm by simply translating one axicon along the optical axis. Trapping experiments with microspheres and dog sperm demonstrate the feasibility of the system, and the power requirement agrees with theoretical expectation. This new type of laser trapping could provide a prototype of a parallel, objective, and quantitative tool for animal fertility and biotropism study.

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

    NASA Technical Reports Server (NTRS)

    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.

  8. Final Technical Report for the MIT Annular Fuel Research Project

    SciTech Connect

    Mujid S. Kazimi; Pavel Hejzlar

    2008-01-31

    MIT-NFC-PR-082 (January 2006) Abstract This summary provides an overview of the results of the U.S. DOE funded NERI (Nuclear Research ENergy Initiative) program on development of the internally and externally cooled annular fuel for high power density PWRs. This new fuel was proposed by MIT to allow a substantial increase in poer density (on the order of 30% or higher) while maintaining or improving safety margins. A comprehensive study was performed by a team consisting of MIT (lead organization), Westinghuse Electric Corporation, Gamma Engineering Corporation, Framatome ANP(formerly Duke Engineering) and Atomic Energy of Canada Limited.

  9. Analysis of a deconvolution-based information retrieval algorithm in X-ray grating-based phase-contrast imaging

    NASA Astrophysics Data System (ADS)

    Horn, Florian; Bayer, Florian; Pelzer, Georg; Rieger, Jens; Ritter, André; Weber, Thomas; Zang, Andrea; Michel, Thilo; Anton, Gisela

    2014-03-01

    Grating-based X-ray phase-contrast imaging is a promising imaging modality to increase soft tissue contrast in comparison to conventional attenuation-based radiography. Complementary and otherwise inaccessible information is provided by the dark-field image, which shows the sub-pixel size granularity of the measured object. This could especially turn out to be useful in mammography, where tumourous tissue is connected with the presence of supertiny microcalcifications. In addition to the well-established image reconstruction process, an analysis method was introduced by Modregger, 1 which is based on deconvolution of the underlying scattering distribution within a single pixel revealing information about the sample. Subsequently, the different contrast modalities can be calculated with the scattering distribution. The method already proved to deliver additional information in the higher moments of the scattering distribution and possibly reaches better image quality with respect to an increased contrast-to-noise ratio. Several measurements were carried out using melamine foams as phantoms. We analysed the dependency of the deconvolution-based method with respect to the dark-field image on different parameters such as dose, number of iterations of the iterative deconvolution-algorithm and dark-field signal. A disagreement was found in the reconstructed dark-field values between the FFT method and the iterative method. Usage of the resulting characteristics might be helpful in future applications.

  10. Numerical simulation research and applications on scattering imaging of surface defects on optical components

    NASA Astrophysics Data System (ADS)

    Chai, Huiting; Cao, Pin; Yang, Yongying; Li, Chen; Wu, Fan; Zhang, Yihui; Xiong, Haoliang; Zhou, Lin; Yan, Kai; Xu, Wenlin; Liu, Dong; Bai, Jian; Shen, Yibing

    2016-11-01

    The principle of microscopic scattering dark-field imaging is adopted in surface defects evaluation system (SDES) for large fine optics. However, since defects are of micron or submicron scale, scattering imaging cannot be described simply by geometrical imaging. In this paper, the simulation model of the electromagnetic field in defect scattering imaging is established on the basis of Finite-Difference Time-Domain (FDTD) method to study the scattering imaging properties of rectangular and triangular defects with different sizes by simulation. The criterion board with scribed lines and dots on it is used to carry out experiments scattering imaging and obtain grayscale value distributions of scattering dark-field images of scribed lines. The experiment results are in good agreement with the simulation results. Based on the above analysis, defect width extraction width is preliminary discussed. Findings in this paper could provide theoretical references for defect calibration in optical fabrication and inspection.

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

    NASA Astrophysics Data System (ADS)

    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. Gouy phase shift for annular beam profiles in attosecond experiments.

    PubMed

    Schlaepfer, F; Ludwig, A; Lucchini, M; Kasmi, L; Volkov, M; Gallmann, L; Keller, U

    2017-02-20

    Attosecond pump-probe measurements are typically performed by combining attosecond pulses with more intense femtosecond, phase-locked infrared (IR) pulses because of the low average photon flux of attosecond light sources based on high-harmonic generation (HHG). Furthermore, the strong absorption of materials at the extreme ultraviolet (XUV) wavelengths of the attosecond pulses typically prevents the use of transmissive optics. As a result, pump and probe beams are typically recombined geometrically with a center-hole mirror that reflects the larger IR beam and transmits the smaller XUV, which leads to an annular beam profile of the IR. This modification of the IR beam can affect the pump-probe measurements because the propagation that follows the reflection on the center-hole mirror can strongly deviate from that of an ideal Gaussian beam. Here we present a detailed experimental study of the Gouy phase of an annular IR beam across the focus using a two-foci attosecond beamline and the RABBITT (reconstruction of attosecond beating by interference of two-photon transitions) technique. Our measurements show a Gouy phase shift of the truncated beam as large as 2π and a corresponding rate of 50 as/mm time delay change across the focus in a RABBITT measurement. These results are essential for attosecond pump-probe experiments that compare measurements of spatially separated targets.

  13. A Compact Annular Ring Microstrip Antenna for WSN Applications

    PubMed Central

    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. PMID:23012510

  14. Characterization of interfacial waves in horizontal core-annular flow

    NASA Astrophysics Data System (ADS)

    Tripathi, Sumit; Bhattacharya, Amitabh; Singh, Ramesh; Tabor, Rico F.

    2016-11-01

    In this work, we characterize interfacial waves in horizontal core annular flow (CAF) of fuel-oil and water. Experimental studies on CAF were performed in an acrylic pipe of 15.5mm internal diameter, and the time evolution of the oil-water interface shape was recorded with a high speed camera for a range of different flow-rates of oil (Qo) and water (Qw). The power spectrum of the interface shape shows a range of notable features. First, there is negligible energy in wavenumbers larger than 2 π / a , where a is the thickness of the annulus. Second, for high Qo /Qw , there is no single dominant wavelength, as the flow in the confined annulus does not allow formation of a preferred mode. Third, for lower Qo /Qw , a dominant mode arises at a wavenumber of 2 π / a . We also observe that the power spectrum of the interface shape depends weakly on Qw, and strongly on Qo, perhaps because the net shear rate in the annulus appears to depend weakly on Qw as well. We also attempt to build a general empirical model for CAF by relating the interfacial stress (calculated via the mean pressure gradient) to the flow rate in the annulus, the annular thickness and the core velocity. Authors are thankful to Orica Mining Services (Australia) for the financial support.

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

    PubMed

    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.

  16. Critical Heat Flux in a Thin Annular Channel

    NASA Astrophysics Data System (ADS)

    Habtour, Ahmed; Anderson, Elgin

    2002-11-01

    The improved accuracy in predicting critical heat flux (CHF) for specific reactor core geometry would allow for increased power output. The objectives of this project were to incorporate a scale model test to determine the feasibility of generating high power density in an annular fuel arrangement in a reactor. The desired power density was 100W/cm2. This would be accomplished by using resistive heating on the outer cylinder of an annular flow channel between concentric cylinders. The inner cylinder consists of a hemispherical shape in the upstream direction to condition the flow. The second objective was to study the behavior of two-phase flow through a simulated reactor core. The CHF would be measured and compared with existing correlations. Finally, the concept of a future full scale testing would be investigated. The results of this project are not only applicable to nuclear reactors, but can be used to increase the efficiency of other applications such as fuel cells, combustion engines, turbines and polymer processes.

  17. Design Attributes and Scale Up Testing of Annular Centrifugal Contactors

    SciTech Connect

    David H. Meikrantz; Jack D. Law

    2005-04-01

    Annular centrifugal contactors are being used for rapid yet efficient liquid- liquid processing in numerous industrial and government applications. Commercialization of this technology began eleven years ago and now units with throughputs ranging from 0.25 to 700 liters per minute are readily available. Separation, washing, and extraction processes all benefit from the use of this relatively new commercial tool. Processing advantages of this technology include: low in-process volume per stage, rapid mixing and separation in a single unit, connection-in-series for multi-stage use, and a wide operating range of input flow rates and phase ratios without adjustment. Recent design enhancements have been added to simplify maintenance, improve inspection ability, and provide increased reliability. Cartridge-style bearing and mechanical rotary seal assemblies that can include liquid-leak sensors are employed to enhance remote operations, minimize maintenance downtime, prevent equipment damage, and extend service life. Clean-in-place capability eliminates the need for disassembly, facilitates the use of contactors for feed clarification, and can be automated for continuous operation. In nuclear fuel cycle studies, aqueous based separations are being developed that efficiently partition uranium, actinides, and fission products via liquid-liquid solvent extraction. Thus, annular centrifugal contactors are destined to play a significant role in the design of such new processes. Laboratory scale studies using mini-contactors have demonstrated feasibility for many such separation processes but validation at an engineering scale is needed to support actual process design.

  18. Oscillation Characteristics of Thermocapillary Convection in An Open Annular Pool

    NASA Astrophysics Data System (ADS)

    Duan, Li; Kang, Qi; Zhang, Di

    2016-07-01

    Temperature oscillation characteristics and free surface deformation are essential phenomena in fluids with free surface. We report experimental oscillatory behaviors for hydrothermal wave instability in thermocapillary-driven flow in an open annular pool of silicone oil. The annular pool is heated from the inner cylindrical wall with the radius 4mm and cooled at the outer wall with radius 20mm, and the depth of the silicone oil layer is in the range of 0.8mm-3mm.Temperature difference between the two sidewalls was increased gradually, and the flow will become unstable via a super critical temperature difference. In the present paper we used T-type thermocouple measuring the single-point temperature inside the liquid layer and captured the tiny micrometer wave signal through a high-precision laser displacement sensor. The critical temperature difference and critical Ma number of onset of oscillation have been obtained. We discussed the critical temperature difference and critical Marangoni number varies with the change of the depth of liquid layer, and the relationship between the temperature oscillation and surface oscillation has been discussed. Experimental results show that temperature oscillation and surface oscillation start almost at the same time with similar spectrum characteristic.

  19. Flow properties of particles in a model annular shear cell

    NASA Astrophysics Data System (ADS)

    Wang, X.; Zhu, H. P.; Yu, A. B.

    2012-05-01

    In order to quantitatively investigate the mechanical and rheological properties of solid flow in a shear cell under conditions relevant to those in an annular cell, we performed a series of discrete particle simulations of slightly polydispersed spheres from quasi-static to intermediate flow regimes. It is shown that the average values of stress tensor components are uniformly distributed in the cell space away from the stationary walls; however, some degree of inhomogeneity in their spatial distributions does exist. A linear relationship between the (internal/external) shear and normal stresses prevails in the shear cell and the internal and external friction coefficients can compare well with each other. It is confirmed that annular shear cells are reasonably effective as a method of measuring particle flow properties. The so-called I-rheology proposed by Jop et al. [Nature (London) 441, 727 (2006)] is rigorously tested in this cell system. The results unambiguously display that the I-rheology can effectively describe the intermediate flow regime with a high correlation coefficient. However, significant deviations take place when it is applied to the quasi-static regime, which corresponds to very small values of inertial number.

  20. The Effect of Nonuniform Inlet Conditions on Annular Diffusers

    NASA Astrophysics Data System (ADS)

    Padilla, Angelina; Elkins, Chris; Eaton, John

    2010-11-01

    Most practical diffusers have complex 3D geometries and may have highly disturbed inlet flows. The performance of diffusers designed for optimum pressure recovery is governed by flow separation which can be very sensitive to inlet perturbations. We are examining the effect of upstream disturbances on the performance of practical annular diffusers. Experiments are conducted in an annular diffuser sector containing a single NACA 0015 airfoil shaped support strut. Three component, time averaged velocities are measured using magnetic resonance velocimetry and static pressure data are measured with conventional wall taps. We are testing four inlet conditions: a uniform velocity profile with thin boundary layers and relatively low turbulence intensity, a similar case with higher turbulence levels, a mean profile with uniform velocity except for a high velocity wall jet at the outer radius, and a nonuniform profile in which the mean velocity decreases with increasing radius. Generally, the results show that the diffuser acts to increase flow distortion. For the case with the radial velocity gradient, passing through the diffuser strongly increases the velocity gradient. The wall jet on the outer (diffusing) wall eliminates flow separation resulting in higher pressure recovery and thicker wall boundary layers on the other three walls. Interestingly, the separated wake of the support strut closes more rapidly for the case with the radial velocity gradient.

  1. Novel applications of continuous annular chromatography: Separation of sugars

    SciTech Connect

    Howard, A.J.; Carta, G.; Byers, C.H.

    1987-01-01

    Continuous chromatographic separations of fructose-glucose-sucrose mixtures have been investigated experimentally in a laboratory-scale continuous annular chromatograph using Ca-exchanged Dowex 50W-X8 resin as adsorbent. Comparative chromatographic separation studies have also been conducted for the system using a conventional fixed-bed column packed with the same resin. Complete resolution of fructose-glucose mixtures could be obtained both in a 60 cm-long continuous annular chromatograph and in a conventional column of the same length with sugars feed concentration up to 200 g/L. In the four-component mixture blue dextran (higher molecular weight saccharide), sucrose, glucose and fructose complete rsolution of all species except sucrose-glucose under the relatively mild separating conditions tested. The experimental results have been analyzed in terms of approximate linear chromatographic theories for fixed and rotating beds. Bed properties and equilibrium and mass transfer parameters used in the model were obtained through independent experiments. With these parameters a good fit to the experimental results was obtained. Differences in feed mixtures and dispersion characteristics contribute to the minor offset between fixed bed and continuous chromatograph results. 21 refs., 12 figs., 3 tabs.

  2. Baroclinic annular variability of internal motions in a Patagonian fjord

    NASA Astrophysics Data System (ADS)

    Ross, Lauren; Valle-Levinson, Arnoldo; Pérez-Santos, Iván.; Tapia, Fabian J.; Schneider, Wolfgang

    2015-08-01

    Time series of horizontal velocities, echo intensity, wind velocity, and atmospheric pressure were collected for ˜200 days in a Patagonian fjord to explore pycnocline motions produced by the Southern Hemisphere's baroclinic annular mode (BAM). The BAM variability occurs between 20 and 30 days and is associated with fluctuations in atmospheric kinetic energy and in turbulent fluxes of heat. Spectra of horizontal velocities and normalized echo intensity in the fjord's water showed highest energy between 25 and 30 days. This was explained by sustained westerly winds associated with extreme low-pressure systems (˜900 hPa) that had periodicity related to the BAM. Wind forcing produced >40 cm s-1 along-channel and cross-channel currents in the surface layer, which in turn created a wind-induced setup toward the head of the fjord. The setup was accompanied by a deepening of the pycnocline (from 5 to 15 m depth) with ˜25 to 30 day periodicity, as derived from the normalized echo intensity. The dominant empirical orthogonal function mode of the normalized echo intensity profiles explained 70.8% of the variance and also exhibited a ˜25-30 day periodicity. Further, a wavelet and spectral analysis of 10 years of atmospheric pressure indicated peaks between 25 and 30 days each year, indicating that the BAM consistently influences weather patterns in Chilean Patagonia. This is the first documented case of baroclinic annular variability in a specific region of the Southern Hemisphere, and of its effects on fjord systems.

  3. Mount assembly for porous transition panel at annular combustor outlet

    NASA Technical Reports Server (NTRS)

    Sweeney, Ralph B. (Inventor); Verdouw, Albert J. (Inventor)

    1980-01-01

    A gas turbine engine combustor assembly of annular configuration has outer and inner walls made up of a plurality of axially extending multi-layered porous metal panels joined together at butt joints therebetween and each outer and inner wall including a transition panel of porous metal defining a combustor assembly outlet supported by a combustor mount assembly including a stiffener ring having a side undercut thereon fit over a transition panel end face; and wherein an annular weld joins the ring to the end face to transmit exhaust heat from the end face to the stiffener ring for dissipation from the combustor; a combustor pilot member is located in axially spaced, surrounding relationship to the end face and connector means support the stiffener ring in free floating relationship with the pilot member to compensate for both radial and axial thermal expansion of the transition panel; and said connector means includes a radial gap for maintaining a controlled flow of coolant from outside of the transition panel into cooling relationship with the stiffener ring and said weld to further cool the end face against excessive heat build-up therein during flow of hot gas exhaust through said outlet.

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

    PubMed

    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.

  5. Annular Lichenoid Dermatitis of Youth: A Chronic Case Managed Using Pimecrolimus.

    PubMed

    Malachowski, Stephen J; Creasey, Mackenzie; Kinkley, Nancy; Heaphy, Michael R

    2016-11-01

    Annular lichenoid dermatitis of youth, first described in 2003, is a rare and occasionally chronic skin disease. We report a case of annular lichenoid dermatitis of youth relapsing over the course of 5 years successfully treated and maintained with topical pimecrolimus cream.

  6. Simultaneous occurrence of ulcerated necrobiosis lipoidica and granuloma annulare in a patient: case report.

    PubMed

    Souza, Fernanda Homem de Mello de; Ribeiro, Camila Ferrari; Pereira, Marcela Abou Chami; Mesquita, Lismary; Fabrício, Lincoln

    2011-01-01

    Simultaneous occurrence of granuloma annulare and necrobiosis lipoidica is quite rare. There are seven reported cases in the literature, but only one presenting ulcerated necrobiosis lipoidica. We report a 39-year-old male with histopathologically confirmed granuloma annulare and ulcerated necrobiosis lipoidica, without diabetes mellitus.

  7. Analytical model of an Annular Momentum Control Device (AMCD) laboratory test model magnetic bearing actuator

    NASA Technical Reports Server (NTRS)

    Groom, N. J.

    1979-01-01

    An analytical model of an Annular Momentum Control Device (AMCD) laboratory test model magnetic bearing actuator with permanent magnet fluxbiasing is presented. An AMCD consists of a spinning annular rim which is suspended by a noncontacting linear electromagnetic spin motor. The actuator is treated as a lumped-parameter electromechanical system in the development of the model.

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

    DOEpatents

    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.

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

    NASA Technical Reports Server (NTRS)

    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.

  10. [Flow field test on the tangential section of polypropylene tubular membrane module annular gap in rotating linear tangential flow].

    PubMed

    Wang, Chengduan; Chen, Wenmei; Li, Jianming; Jiang, Guangming

    2002-07-01

    A new type of polypropylene tubular membrane apparatus of rotating cross flow was designed to study experimentally the flow field characteristics of the tangential section of the membrane annular gap. The authors designed rotary linear tangential flow tubular membrane separator and its test system for the first time. Through the system, the flow field of rotary linear tangential flow with the advanced Particle Image Velocimetry (PIV) was tested for the first time. A lot of streamlines and vorticity maps of the tangential section of separator in different operation conditions were obtained. The velocity distribution characteristics were analyzed quantitatively: 1. At non-vortex area, no matter how the operation parameters change, the velocity near to rotary tangential flow entrance was higher than the velocity far from entrance at the same radial coordinates. At vortex area, generally the flow velocity of inner vortex was lower than the outer vortex. At the vortex center, the velocity was lowest, the tangential velocity were equal to zero generally. At the vortex center zone, the tangential velocity was less than the axial velocity. 2. Under test operations, the tangential velocity and axial velocity of vortices borders are 1-2 times of average axial velocity of membrane module annular gap. The maximum tangential velocity and axial velocity of ellipse vortices were 2-6 times of average axial velocity of membrane module annular gap. 3. The vortices that are formed on the tangential section, there existed mass transfer between inner and outer parts of fluid. Much fluid of outer vortices got into the inner ones, which was able to prevent membrane tube from particles blocking up very soon.

  11. Enhanced simulation software for rocket turbopump, turbulent, annular liquid seals

    NASA Technical Reports Server (NTRS)

    Padavala, Satya; Palazzolo, Alan

    1994-01-01

    One of the main objectives of this work is to develop a new dynamic analysis for liquid annular seals with arbitrary profile and to analyze a general distorted interstage seal of the space shuttle main engine high pressure oxygen turbopump (SSME-ATD-HPOTP). The dynamic analysis developed is based on a method originally proposed by Nelson and Nguyen. A simpler scheme based on cubic splines is found to be computationally more efficient and has better convergence properties at higher eccentricities. The first order solution of the original analysis is modified by including a more exact solution that takes into account the variation of perturbed variables along the circumference. A new set of equations for dynamic analysis are derived based on this more general model. A unified solution procedure that is valid for both Moody's and Hirs' friction models is presented. Dynamic analysis is developed for three different models: constant properties, variable properties, and thermal effects with variable properties. Arbitrarily varying seal profiles in both axial and circumferential directions are considered. An example case of an elliptical seal with varying degrees of axial curvature is analyzed in detail. A case study based on predicted clearances of an interstage seal of the SSME-ATD-HPOTP is presented. Dynamic coefficients based on external specified load are introduced to analyze seals that support a preload. The other objective of this work is to study the effect of large rotor displacements of SSME-ATD-HPOTP on the dynamics of the annular seal and the resulting transient motion. One task is to identify the magnitude of motion of the rotor about the centered position and establish limits of effectiveness of using current linear models. This task is accomplished by solving the bulk flow model seal governing equations directly for transient seal forces for any given type of motion, including motion with large eccentricities. Based on the above study, an equivalence is

  12. Theory of low voltage annular beam free-electron lasers

    SciTech Connect

    Blank, M.; Freund, H.P.; Jackson, R.H.

    1995-12-31

    An nonlinear analysis of an annular beam propagating through a cylindrical waveguide in the presence of a helical wiggler and an axial guide field is presented. The analysis is based upon the ARACHNE simulation which is a non-wiggler-averaged slow-time-scale simulation code in which the electromagnetic field is represented as a superposition of the TE and TM modes in a vacuum waveguide, and the beam space-charge waves are represented as a superposition of Gould-Trivelpiece modes. The DC self-electric and self-magnetic fields are also included in the model. ARACHNE has been extensively benchmarked against experiments at MIT and NRL in the past with good agreement, but all of these experiments have dealt with solid electron beams and beam voltages in excess of 200 kV. In seeking to reduce the beam voltage requirements we now consider the effect of operation with an annular beam. One advantage to be obtained by using an annular beam is that, for a fixed beam current, the effect of the DC selffields (i.e., the space-charge depression in beam voltage) will be reduced relative to that of a solid beam. This facilitates beam transport in short period wigglers in which the transverse dimensions are also small. A specific example is under study which makes use of 55 kV/5A electron beam with inner and outer radii of 0.27 cm and 0.33 cm respectively. The wiggler amplitude is 250 G with a period of 0.9 cm. and guide fields up to 3 kG corresponding to Group I trajectories. The waveguide radius is chosen to correspond to grazing incidence for the fundamental mode in Ku-Band (12-18 GHz). Preliminary results indicate that efficiencies upwards of 10% are possible with no wiggler taper. In addition, the energy spread must be held below 0.1%, and the instantaneous bandwidth is found to be greater than 20%.

  13. The second-order differential phase contrast and its retrieval for imaging with x-ray Talbot interferometry

    SciTech Connect

    Yang Yi; Tang Xiangyang

    2012-12-15

    Purpose: The x-ray differential phase contrast imaging implemented with the Talbot interferometry has recently been reported to be capable of providing tomographic images corresponding to attenuation-contrast, phase-contrast, and dark-field contrast, simultaneously, from a single set of projection data. The authors believe that, along with small-angle x-ray scattering, the second-order phase derivative {Phi}{sup Double-Prime }{sub s}(x) plays a role in the generation of dark-field contrast. In this paper, the authors derive the analytic formulae to characterize the contribution made by the second-order phase derivative to the dark-field contrast (namely, second-order differential phase contrast) and validate them via computer simulation study. By proposing a practical retrieval method, the authors investigate the potential of second-order differential phase contrast imaging for extensive applications. Methods: The theoretical derivation starts at assuming that the refractive index decrement of an object can be decomposed into {delta}={delta}{sub s}+{delta}{sub f}, where {delta}{sub f} corresponds to the object's fine structures and manifests itself in the dark-field contrast via small-angle scattering. Based on the paraxial Fresnel-Kirchhoff theory, the analytic formulae to characterize the contribution made by {delta}{sub s}, which corresponds to the object's smooth structures, to the dark-field contrast are derived. Through computer simulation with specially designed numerical phantoms, an x-ray differential phase contrast imaging system implemented with the Talbot interferometry is utilized to evaluate and validate the derived formulae. The same imaging system is also utilized to evaluate and verify the capability of the proposed method to retrieve the second-order differential phase contrast for imaging, as well as its robustness over the dimension of detector cell and the number of steps in grating shifting. Results: Both analytic formulae and computer

  14. Measurement of mitral leaflet and annular geometry and stress after repair of posterior leaflet prolapse: Virtual repair using a patient specific finite element simulation

    PubMed Central

    Ge, Liang; Morrel, William G.; Ward, Alison; Mishra, Rakesh; Zhang, Zhihong; Guccione, Julius M.; Grossi, Eugene A.; Ratcliffe, Mark B.

    2014-01-01

    Background Recurrent mitral regurgitation after mitral valve (MV) repair for degenerative disease occurs at a rate of 2.6% per year and re-operation rate progressively reaches 20% at 19.5 years. We believe that MV repair durability is related to initial post-operative leaflet and annular geometry with subsequent leaflet remodeling due to stress. We tested the hypothesis that MV leaflet and annular stress is increased after MV repair. Methods Magnetic resonance imaging was performed before and intra-operative 3D trans-esophageal echocardiography was performed before and after repair of posterior leaflet (P2) prolapse in a single patient. The repair consisted of triangular resection and annuloplasty band placement. Images of the heart were manually co-registered. The left ventricle and MV were contoured, surfaced and a 3D finite element (FE) model was created. Elements of the P2 region were removed to model leaflet resection and virtual sutures were used to repair the leaflet defect and attach the annuloplasty ring. Results The principal findings of the current study are 1) FE simulation of MV repair is able to accurately predict changes in MV geometry including changes in annular dimensions and leaflet coaptation, 2) average posterior leaflet stress is increased, and 3) average anterior leaflet and annular stress are reduced after triangular resection and mitral annuloplasty. Conclusions We successfully conducted virtual mitral valve prolapse repair using FE modeling methods. Future studies will examine the effects of leaflet resection type as well as annuloplasty ring size and shape. PMID:24630767

  15. Annular suspension and pointing system with controlled DC electromagnets

    NASA Technical Reports Server (NTRS)

    Vu, Josephine Lynn; Tam, Kwok Hung

    1993-01-01

    The Annular Suspension and Pointing System (ASPS) developed by the Flight System division of Sperry Corporation is a six-degree of freedom payload pointing system designed for use with the space shuttle. This magnetic suspension and pointing system provides precise controlled pointing in six-degrees of freedom, isolation of payload-carrier disturbances, and end mount controlled pointing. Those are great advantages over the traditional mechanical joints for space applications. In this design, we first analyzed the assumed model of the single degree ASPS bearing actuator and obtained the plant dynamics equations. By linearizing the plant dynamics equations, we designed the cascade and feedback compensators such that a stable and satisfied result was obtained. The specified feedback compensator was computer simulated with the nonlinearized plant dynamics equations. The results indicated that an unstable output occurred. In other words, the designed feedback compensator failed. The failure of the design is due to the Taylor's series expansion not converging.

  16. Dynamic force and moment coefficients for short length annular seals

    NASA Astrophysics Data System (ADS)

    San Andres, Luis

    1993-01-01

    Close form expressions for the dynamic force and moment coefficients in short length annular pressure seals operating at the concentric and aligned position are derived. The analysis considers fully developed turbulent flow within the seal and determines a set of ordinary differential equations for the bulk-flow field due to perturbations in rotor displacements and angular motions. The flow equations are solved exactly for seals of short length where dynamic variations in circumferential velocity are neglected. The analytical solution derived is simple and reasonably accurate for seals of length to diameter ratios (L/D) as large as 0.5 as comparisons with results from full-scale numerical solutions show. The formulae presented are practical for use in preliminary design stages and parametric studies of dynamic seal performance.

  17. Geometry-Driven Folding of a Floating Annular Sheet.

    PubMed

    Paulsen, Joseph D; Démery, Vincent; Toga, K Buğra; Qiu, Zhanlong; Russell, Thomas P; Davidovitch, Benny; Menon, Narayanan

    2017-01-27

    Predicting the large-amplitude deformations of thin elastic sheets is difficult due to the complications of self contact, geometric nonlinearities, and a multitude of low-lying energy states. We study a simple two-dimensional setting where an annular polymer sheet floating on an air-water interface is subjected to different tensions on the inner and outer rims. The sheet folds and wrinkles into many distinct morphologies that break axisymmetry. These states can be understood within a recent geometric approach for determining the gross shape of extremely bendable yet inextensible sheets by extremizing an appropriate area functional. Our analysis explains the remarkable feature that the observed buckling transitions between wrinkled and folded shapes are insensitive to the bending rigidity of the sheet.

  18. Annular resonators for high-power chemical lasers

    NASA Astrophysics Data System (ADS)

    Wade, Richard C.

    1993-08-01

    Resonators capable of extracting highly coherent energy from DF and HF chemical laser annular gain media have been under investigation for weapon application since 1974. This survey article traces the background of interest in these devices, describes the various concepts that have been experimentally and analytically investigated, and discusses the issues associated with their operation. From the discussion of issues, preferred concepts are selected. Applicability of these concepts to high-power operation is addressed through discussions of past and ongoing high-power demonstration programs and the issues facing their application to weapon sized devices capable of strategic and tactical missions such as ballistic missile defense (BMD), theater missile defense (TMD), and anti satellite (ASAT).

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

    SciTech Connect

    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.

  20. Hydrodynamics of annular-dispersed flow. [PWR; BWR

    SciTech Connect

    Ishii, M.; Kataoka, I.

    1982-01-01

    The interfacial drag, droplet entrainment, and droplet size distributions are important for detailed mechanistic modeling of annular dispersed two-phase flow. In view of this, recently developed correlations for these parameters are presented and discussed in this paper. The drag correlations for multiple fluid particle systems have been developed from a similarity hypothesis based on the mixture viscosity model. The results show that the drag coefficient depends on the particle Reynolds number and droplet concentration. The onset on droplet entrainment significantly alters the mechanisms of mass, momentum, and energy transfer between the film and gas core flow as well as the transfer between the two-phase mixture and the wall. By assuming the roll wave entrainment mechanism, the correlations for the amount of entrained droplet as well as for the droplet size distribution have been obtained from a simple model in collaboration with a large number of data.

  1. The liquid annular reactor system (LARS) for deep space exploration

    NASA Astrophysics Data System (ADS)

    Maise, George; Paniagua, John; Powell, James R.; Ludewig, Hans; Todosow, Michael

    1999-05-01

    A new propulsion concept for high Δ V space missions, termed LARS (Liquid Annular Reactor System), uses liquid nuclear fuel elements to heat hydrogen propellant to very high temperatures (-6000 K). The molten fuel is contained in a lower-temperature solid container which rotates to stabilize and hold in the liquid layer by centripetal force. Containment of ultra high temperature molten refractories, using this method, has been experimentally demonstrated by A.V. Grosse. The specific impulse of a rocket exhausting hydrogen at 6000 K is 2000 seconds, approximately double that of solid-core nuclear rockets. A LARS-powered space probe could accomplish extra-solar missions to 550 A.U. in approximately 35 years.

  2. Annular Plaques on the Tongue: What Is Your Diagnosis?

    PubMed Central

    Kayhan, Tuba Çelebĺ; Bĺlaç, Cemal; Bĺlaç, Dilek Bayraktar; Ecemĺş, Talat

    2011-01-01

    Geographic tongue is an inflammatory disorder of the tongue characterized by asymptomatic erythematous patches with serpiginous borders. Candidiasis of the tongue may be confused with geographic tongue. A 63-year-old male patient with painful white annular lesions localized to the left side of his tongue is presented. He applied topical corticosteroid and antiinflammatory agents, but his lesions did not respond to those therapies. Using direct mycologic examination and culture, the patient was diagnosed with candidiasis. After systemic and topical antifungal therapy, clinical improvement was observed. With this case, the clinical forms of oral candidiasis were discussed, and it was suggested that the clinical presentation of mucosal candidiasis may vary according to the stage of infection and individual immunity. PMID:22148032

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

    NASA Technical Reports Server (NTRS)

    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.

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

    SciTech Connect

    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.

  5. The Effect of Upstream Vane Wakes on Annular Diffuser Flows

    NASA Astrophysics Data System (ADS)

    Cherry, Erica; Padilla, Angelina; Elkins, Christopher; Eaton, John

    2008-11-01

    Experiments were performed to determine the sensitivity to inlet conditions of the flow in two annular diffusers. One of the diffusers was a conservative design typical of a diffuser directly upstream of the combustor in a jet engine. The other had the same length and inlet shape as the first diffuser but a larger area ratio and was meant to operate on the verge of separation. Each diffuser was connected to two different inlets, one containing a fully-developed channel flow, the other containing wakes from a row of airfoils. Three-component velocity measurements were taken on the flow in each inlet/diffuser combination using Magnetic Resonance Velocimetry. Results will be presented on the 3D velocity fields in the two diffusers and the effect of the airfoil wakes on separation and secondary flows.

  6. Aerodynamic performance of an annular classical airfoil cascade

    NASA Technical Reports Server (NTRS)

    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.

  7. Annular billiard dynamics in a circularly polarized strong laser field

    NASA Astrophysics Data System (ADS)

    Kamor, A.; Mauger, F.; Chandre, C.; Uzer, T.

    2012-01-01

    We analyze the dynamics of a valence electron of the buckminsterfullerene molecule (C60) subjected to a circularly polarized laser field by modeling it with the motion of a classical particle in an annular billiard. We show that the phase space of the billiard model gives rise to three distinct trajectories: “whispering gallery orbits,” which hit only the outer billiard wall; “daisy orbits,” which hit both billiard walls (while rotating solely clockwise or counterclockwise for all time); and orbits that only visit the downfield part of the billiard, as measured relative to the laser term. These trajectories, in general, maintain their distinct features, even as the intensity is increased from 1010 to 1014Wcm-2. We attribute this robust separation of phase space to the existence of twistless tori.

  8. Geometry-Driven Folding of a Floating Annular Sheet

    NASA Astrophysics Data System (ADS)

    Paulsen, Joseph D.; Démery, Vincent; Toga, K. Buǧra; Qiu, Zhanlong; Russell, Thomas P.; Davidovitch, Benny; Menon, Narayanan

    2017-01-01

    Predicting the large-amplitude deformations of thin elastic sheets is difficult due to the complications of self contact, geometric nonlinearities, and a multitude of low-lying energy states. We study a simple two-dimensional setting where an annular polymer sheet floating on an air-water interface is subjected to different tensions on the inner and outer rims. The sheet folds and wrinkles into many distinct morphologies that break axisymmetry. These states can be understood within a recent geometric approach for determining the gross shape of extremely bendable yet inextensible sheets by extremizing an appropriate area functional. Our analysis explains the remarkable feature that the observed buckling transitions between wrinkled and folded shapes are insensitive to the bending rigidity of the sheet.

  9. Thirty Stage Annular Centrifugal Contactor Thermal Profile Measurements

    SciTech Connect

    David H. Meikrantz; Troy G. Garn; Jack D. Law

    2010-02-01

    A thirty stage 5 cm annular centrifugal contactor cascade has been assembled and tested to obtain thermal profiles during both ambient and heated input conditions of operation. Thermocouples were installed on every stage as well as feed inputs and Real-time data was taken during experiments lasting from two to eight hours at total flow rates of 0.5 to 1.4 liters per minute. Ambient temperature profile results show that only a small amount of heat is generated by the mechanical energy of the contactors. Steady state temperature profiles mimic the ambient temperature of the lab but are higher toward the middle of the cascade. Heated inlet solutions gave temperature profiles with smaller temperature gradients, more driven by the temperature of the inlet solutions than ambient lab temperature. Temperature effects of solution mixing, even at rotor speeds of 4000 rpm, were not measurable.

  10. Interfacial shear modeling in two-phase annular flow

    SciTech Connect

    Kumar, R.; Edwards, D.P.

    1996-11-01

    A new interfacial shear stress model called the law of the interface model, based on the law of the wall approach in turbulent flows, has been developed and locally applied in a fully developed, adiabatic, two-phase annular flow in a duct. Numerical results have been obtained using this model in conjunction with other models available in the literature that are required for the closure of the continuity and momentum equations. These results have been compared with droplet velocity data (using laser Doppler velocimetry and hot film anemometry), void fraction data (using gamma densitometry) and pressure drop data obtained in a R-134A refrigerant test facility. Droplet velocity results match the experimental data well, however, the prediction of the void fraction is less accurate. The poor prediction of void fraction, especially for the low void fraction cases, appears to be due to the lack of a good mechanistic model for entrainment.

  11. Interfacial shear modeling in two-phase annular flow

    SciTech Connect

    Kumar, R.; Edwards, D.P.

    1996-07-01

    A new interfacial shear stress model called the law of the interface model, based on the law of the wall approach in turbulent flows, has been developed and locally applied in a fully developed, adiabatic, two-phase annular flow in a duct. Numerical results have been obtained using this model in conjunction with other models available in the literature that are required for the closure of the continuity and momentum equations. These results have been compared with droplet velocity data (using laser Doppler velocimetry and hot film anemometry), void fraction data (using gamma densitometry) and pressure drop data obtained in a R-134A refrigerant test facility. Droplet velocity results match the experimental data well, however, the prediction of the void fraction is less accurate. The poor prediction of void fraction, especially for the low void fraction cases, appears to be due to the lack of a good mechanistic model for entrainment.

  12. Interfacial transfer in annular dispersed flow. [PWR; BWR

    SciTech Connect

    Ishii, M.; Kataoka, I.

    1982-01-01

    The interfacial drag, droplet entrainment, droplet deposition and droplet-size distributions are important for detailed mechanistic modeling of annular dispersed two-phase flow. In view of this, recently developed correlations for these parameters are presented and discussed in this paper. The onset of droplet entrainment significantly alters the mechanisms of mass, momentum, and energy transfer between the film and gas core flow as well as the transfer between the two-phase mixture and the wall. By assuming the roll wave entrainment mechanism, the correlations for the amount of entrained droplet as well as for the droplet-size distribution have been obtained from a simple model in collaboration with a large number of data. Then the rate equations for entrainment and deposition have been developed. The drag correlations relevant to the droplet transfer is also presented. The comparison of the correlations to various data show satisfactory agreement.

  13. Fuel Injector Design Optimization for an Annular Scramjet Geometry

    NASA Technical Reports Server (NTRS)

    Steffen, Christopher J., Jr.

    2003-01-01

    A four-parameter, three-level, central composite experiment design has been used to optimize the configuration of an annular scramjet injector geometry using computational fluid dynamics. The computational fluid dynamic solutions played the role of computer experiments, and response surface methodology was used to capture the simulation results for mixing efficiency and total pressure recovery within the scramjet flowpath. An optimization procedure, based upon the response surface results of mixing efficiency, was used to compare the optimal design configuration against the target efficiency value of 92.5%. The results of three different optimization procedures are presented and all point to the need to look outside the current design space for different injector geometries that can meet or exceed the stated mixing efficiency target.

  14. Annular-beam, 17 GHz free-electron maser experiment

    SciTech Connect

    Earley, L.M.; Carlsten, B.E.; Fazio, M.V.

    1997-06-01

    Experiments have been conducted on a 15-17 GHz free electron maser (FEM) for producing a 500 MW output pulse with a phase stability appropriate for linear collider applications. The electron beam source was a 1 {mu}s, 800 kV, 5 kA, 6-cm-dia annular electron beam machine called BANSHEE. The beam interacted with the TM{sub 02} and TM{sub 03} mode Raman FEM amplifier in a corrugated cylindrical waveguide where the beam runs close to the interaction device walls to reduce the power density in the fields. This greatly reduced the kinetic energy loss caused by the beam potential depression associated with the space charge which was a significant advantage in comparison with conventional solid beam microwave tubes at the same beam current. The experiment was operated in a single shot mode with a large number of diagnostics to measure power, frequency and energy.

  15. Fast High Capacity Annular Gas Puff Valve Design Concept

    NASA Astrophysics Data System (ADS)

    Ruden, Edward

    2000-10-01

    A fast opening gas valve design concept is presented that can theoretically inject a few grams of D2 gas radially outward into a coaxial annular vacuum region with a radius of about 10 cm in less that 100 μ s. The concept employs a single turn 20-30 T pulsed magnetic field coil that axially accelerates an Mg alloy ring, which seals a gas plenum, to high velocity, releasing the gas. Both coil and ring are profiled to minimize stress in the ring. Such a device could be used to supply the initial gas load for a proposed 5 MJ Dense Plasma Focus driven by AFRL's Shiva Star Capacitor bank. The intent here is keep the vacuum current feed insulator under high vacuum during the discharge to avoid surface breakdown. Alternatively, a high energy rep ratable plasma flow opening switch could be supplied with such a valve. This work is funded by the USAF.

  16. Digital controller design: Analysis of the annular suspension pointing system

    NASA Technical Reports Server (NTRS)

    Kuo, B. C.

    1979-01-01

    The Annular Suspension and Pointing System (ASPS) is a payload auxiliary pointing device of the Space Shuttle. The ASPS is comprised of two major subassemblies, a vernier and a coarse pointing subsystem. The experiment is attached to a mounting plate/rim combination which is suspended on magnetic bearing/actuators (MBA) strategically located about the rim. Fine pointing is achieved by gimballing the plate/rim within the MBA gaps. Control about the experiment line-of-sight is obtained through the use of a non-contacting rim drive and positioning torquer. All sensors used to close the servo loops on the vernier system are noncontacting elements. Therefore, the experiment is a free-flyer constrained only by the magnetic forces generated by the control loops.

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

    SciTech Connect

    Babelli, I.; Nair, S.; Ishii, M.

    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.

  18. Closed-cycle annular-flow-return laser

    SciTech Connect

    Olson, R.A.; Sarka, B. Jr.; Garscadden, A.; Bletzinger, P.

    1981-07-01

    A compact, high repetition rate, closed-cycle rare-gas laser has been achieved in a novel design utilizing an annular flow return surrounding the laser flow channel. The 112-cm long by 30.5-cm-diam. laser head is compact and attractive for portable applications. High repetition rate (to 15 kHz) multiline laser operation has been achieved in high-pressure (to 2 atm) mixtures of Ne--Xe (6 lines), Ar--Xe (7 lines), He--Xe (9 lines), He--Kr (4 lines), and He--Ar (3 lines). Reliable long lifetime performance has been demonstrated by operating a He--Xe laser continuously for 100 hours at a pulse-repetition rate of 5 kHz (1.8 x 10/sup 9/ pulses) with no degradation of the 1.1-W average laser output power.

  19. Intermittent Flow of Granular Matter in an Annular Geometry

    NASA Astrophysics Data System (ADS)

    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.

  20. Non-axisymmetric instability of core-annular flow

    NASA Astrophysics Data System (ADS)

    Hu, Howard H.; Patankar, Neelesh

    1995-05-01

    Stability of core-annular flow of water and oil in a vertical circular pipe is studied with respect to non-axisymmetric disturbances. Results show that when the oil core is thin, the flow is most unstable to the asymmetric sinuous mode of disturbance, and the core moves in the form of corkscrew waves as observed in experiments. The asymmetric mode of disturbance is the most dangerous mode for quite a wide range of material and flow parameters. This asymmetric mode persists in vertical pipes with upward and downward flows and in horizontal pipes. The analysis also applies to the instability of freely rising axisymmetric cigarette smoke or a thermal plume. The study predicts a unique wavelength for the asymmetric meandering waves.

  1. Approximants to the Tonks-Langmuir theory for a collisionless annular plasma.

    PubMed

    Zhang, Yunchao; Charles, Christine; Boswell, Rod

    2015-12-01

    Maclaurin series approximant and Padé rational approximant are used to solve the Tonks-Langmuir theory for an annular plasma and investigate the radial transport behavior of charged particles. Coefficients of the well-known Maclaurin approximant are given in a novel form of recurrence relations which are convenient for computation and present a lower limit for the annular ratio of inner radius to outer radius (i.e., this approximant is not applicable to annular geometries with small inner radii). The newly introduced Padé approximant extrapolates the annular ratio limit determined by the Maclaurin approximant to a lower value and hence is applicable to most annular geometries. General radial profiles of the normalized plasma density and mean drift velocity of ions are given across the annulus and they are independent of the gas type and the Paschen number of the discharge. The annular modeling is applied to an argon plasma and obtains the electron temperature as a function of the Paschen number for different annular geometries.

  2. Cold neutron tomography of annular coolant flow in a double subchannel model of a boiling water reactor

    NASA Astrophysics Data System (ADS)

    Kickhofel, J. L.; Zboray, R.; Damsohn, M.; Kaestner, A.; Lehmann, E. H.; Prasser, H.-M.

    2011-09-01

    Dryout of the liquid coolant film on fuel pins at the top of boiling water reactor (BWR) cores constitutes the type of heat transfer crisis relevant for the conditions of high void fractions. It is a limiting factor in the thermal power, and therefore the economy, of BWRs. Ongoing research on multiphase annular flow, specifically the liquid film thickness, is fundamental not only to nuclear reactor safety and operation but also to that of evaporators, condensers, and pipelines in a general industrial context. We have performed cold neutron tomography of adiabatic air water annular flow in a scaled up model of the subchannel geometry found in BWR fuel assemblies today. All imaging has been performed at the ICON beamline at the neutron spallation source SINQ at the Paul Scherrer Institut in Switzerland. Neutron tomography is shown to excel in investigating the interactions of air water two phase flows with spacer vanes of different geometry. The high resolution, high contrast measurements provide spatial distributions of the coolant on top of the surfaces of the spacer, including the vanes, and in the subchannel downstream of the spacers.

  3. Application of exposure simulation system to reduce isolated-dense bias by using annular off-axis illumination

    NASA Astrophysics Data System (ADS)

    Shih, Yi-Nan; Chen, Nien-Po

    2008-11-01

    The optical proximity effect (OPE) is one of the most serious problems, as the optical lithography is pushed into the smaller feature size below the exposure wavelength. Some of the typical ways to solve this problem are to use the optical proximity correction (OPC) and the phase shift mask (PSM). However, these sophisticated techniques increase the cost of making masks, as well as the risk of getting defects on the masks. In this study we optimize the annular off-axis illumination (OAI) conditions to reduce the Isolated-Dense bias (IDB), in order to improve the resolution and the depth of focus (DOF) as a solution to fight for OPE. Through the simulation done with AIMS Fab 248 exposure system, the energy distribution on the photo-resist is analyzed with the intensity distribution across the simulated exposure images. The optimization is performed with the aid of Taguchi method. On the basis of the simulation analysis, the optimum optical parameters (the numerical aperture NA, the degree of coherence Sigma, and the ratio of the inner and the outer radii of the rings Annular) are selected to obtain the high resolution and enough DOF to reduce IDB value. The low IDB can be realized by using optimal optical parameters before exposure processes, without using sophisticated OPC and PSM on the masks.

  4. Sizing defects using annular-array techniques with an automatic ultrasonic data-acquisition system

    SciTech Connect

    Gieske, J.H.; Stoker, G.C.; Walkington, P.D.

    1983-01-01

    The results of sizing internal flaws by a annular phased array technique are presented. The data was taken using a microprocessor controlled phased array pulser/receiver operated with a minicomputer ultrasonic data acquisition system. Flat bottom holes of two sizes which were machined in an aluminum block at various depths were used as targets. Sizing of these targets by the annular array technique is compared with sizing by conventional flat and focused single transducer techniques. The results show that the measured flaw size determined by the annular array technique is to a large extent independent of echo amplitude and flaw depth.

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

    NASA Astrophysics Data System (ADS)

    McQuillen, John B.

    2002-11-01

    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.

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

    NASA Astrophysics Data System (ADS)

    Bousman, W. Scott; McQuillen, John B.

    1994-08-01

    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.

  7. Annular ballast resistor: Symmetry breaking, pinning, and coarsening in a globally constrained reaction-diffusion system

    NASA Astrophysics Data System (ADS)

    Meerson, Baruch; Tsori, Yoav

    1998-01-01

    The wire ballast resistor (BR) is one of the simplest physical systems that exhibit bistability and pattern formation. An annular BR is suggested as a simple two-dimensional extension of the wire BR. The nonuniformity of the electric current density in the annular BR leads to translational symmetry breaking in the temperature domain dynamics. As a result, the steady-state position of the domain wall is ``pinned'' and the system exhibits coarsening. The two-phase steady-state relaxation towards it and coarsening in the annular BR are investigated analytically and numerically.

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

    NASA Technical Reports Server (NTRS)

    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.

  9. High-power test of annular-ring coupled structures for the J-PARC linac energy upgrade

    NASA Astrophysics Data System (ADS)

    Tamura, Jun; Ao, Hiroyuki; Nemoto, Yasuo; Asano, Hiroyuki; Suzuki, Takahiro

    2015-02-01

    Annular-ring coupled structures (ACSs) will increase the beam energy of the Japan proton accelerator research complex (J-PARC) linac from 181 to 400 MeV to achieve a beam power of 1 MW for a materials and life science experimental facility. The mass production of the ACS cavities commenced in March 2009. Before the installation, all cavities require power testing. High-power testing is essential not only for confirming the cavity's design performance but also for preventing delays in cavity conditioning schedule. However, the 2011 Tohoku earthquake damaged J-PARC facilities, including the ACS power-test area, and cavity conditioning was interrupted for two years. After the facility's restoration, two ACS cavities (M01 and M11) were conditioned. They performed 15-20% above the designed accelerating field of 4.2 MV/m. As M01 was initially conditioned six years ago, the most recent conditioning time required for M01 was drastically reduced. From this result, we confirmed that long-term stored ACS cavities purged with nitrogen gas do not produce critical cavity performance issues. During high-power operation of M11, which is a unique cavity equipped with a capacitive iris in a waveguide, no significant increases in the temperature and the discharge rate around the capacitive iris were observed. Even considering beam loss due to residual gas scattering, the vacuum pressure was sufficiently low (4 × 10-6 Pa). More stable operation can be expected following a month-long conditioning process before the beam is commissioned. M11's conditioning successfully demonstrated an auto-conditioning program, and we established the conditioning scheme using this auto-conditioning program for all ACS cavities in a limited time and with limited manpower.

  10. Usefulness of early diastolic mitral annular velocity to predict plasma levels of brain natriuretic peptide and transient heart failure development after device closure of atrial septal defect.

    PubMed

    Masutani, Satoshi; Taketazu, Mio; Mihara, Chihiro; Mimura, Yuko; Ishido, Hirotaka; Matsunaga, Tamotsu; Kobayashi, Toshiki; Senzaki, Hideaki

    2009-12-15

    Device closure of atrial septal defect (ASD) is sometimes followed by elevation of plasma brain natriuretic peptide (BNP), a marker of heart failure, and progression to heart failure. This study tested the hypothesis that the underlying diastolic dysfunction, assessed on tissue Doppler images (TDI) before device closure, can predict BNP level after ASD closure. The study subjects were 39 consecutive patients (age 27.5 +/- 16.3 years, range 5 to 63) who underwent device closure for ASD. Echocardiographic evaluation using TDI and 2-dimensional and pulse wave Doppler were performed, together with plasma BNP measurement 1 day before and 2 days after ASD closure. Before ASD closure, an age-dependent decrease was noted in left ventricular relaxation, assessed by early diastolic mitral annular velocity. ASD closure resulted in a decrease in early diastolic mitral annular velocity (from 14.7 to 12.3 cm/s, p <0.05) despite an increase in the left ventricular dimension (84% to 92% vs normal, p <0.05). These changes were associated with a parallel increase in BNP (17.9 to 48.4 pg/ml, p <0.05). Stepwise multivariate linear regression identified early diastolic mitral annular velocity before ASD closure and age as independent predictors of BNP levels after ASD closure (p <0.05). Consistent with this result, 2 patients with the lowest early diastolic mitral annular velocity developed exertional dyspnea after the procedure. In conclusion, our results indicate that TDI measurements could be useful to detect underlying diastolic dysfunction that can potentially cause heart failure after ASD closure and emphasize the importance of ASD closure at a young age before impairment of left ventricular relaxation.

  11. Annular phased array transducer for preclinical testing of anti-cancer drug efficacy on small animals.

    PubMed

    Kujawska, Tamara; Secomski, Wojciech; Byra, Michał; Postema, Michiel; Nowicki, Andrzej

    2017-04-01

    A technique using pulsed High Intensity Focused Ultrasound (HIFU) to destroy deep-seated solid tumors is a promising noninvasive therapeutic approach. A main purpose of this study was to design and test a HIFU transducer suitable for preclinical studies of efficacy of tested, anti-cancer drugs, activated by HIFU beams, in the treatment of a variety of solid tumors implanted to various organs of small animals at the depth of the order of 1-2cm under the skin. To allow focusing of the beam, generated by such transducer, within treated tissue at different depths, a spherical, 2-MHz, 29-mm diameter annular phased array transducer was designed and built. To prove its potential for preclinical studies on small animals, multiple thermal lesions were induced in a pork loin ex vivo by heating beams of the same: 6W, or 12W, or 18W acoustic power and 25mm, 30mm, and 35mm focal lengths. Time delay for each annulus was controlled electronically to provide beam focusing within tissue at the depths of 10mm, 15mm, and 20mm. The exposure time required to induce local necrosis was determined at different depths using thermocouples. Location and extent of thermal lesions determined from numerical simulations were compared with those measured using ultrasound and magnetic resonance imaging techniques and verified by a digital caliper after cutting the tested tissue samples. Quantitative analysis of the results showed that the location and extent of necrotic lesions on the magnetic resonance images are consistent with those predicted numerically and measured by caliper. The edges of lesions were clearly outlined although on ultrasound images they were fuzzy. This allows to conclude that the use of the transducer designed offers an effective noninvasive tool not only to induce local necrotic lesions within treated tissue without damaging the surrounding tissue structures but also to test various chemotherapeutics activated by the HIFU beams in preclinical studies on small animals.

  12. Investigation of the Left Ventricular Flow Dynamics in the Presence of Severe Mitral Annular Calcification

    NASA Astrophysics Data System (ADS)

    El-Sayegh, Batoul; Kadem, Lyes; di Labbio, Giuseppe; Pressman, Gregg S.; Obasare, Edinrin

    2016-11-01

    Valvular calcification is frequent with aging and diverse diseases. Mitral annular calcification (MAC) is a degenerative process where the fibrous annulus of the mitral valve degrades. MAC can be found in approximately 40% of people aged over 65. It is associated with increased occurrence of cardiovascular diseases including stroke. This experimental work is aimed to investigate the effects of MAC on the left ventricle (LV) hemodynamics and to develop new clinical parameters. Two patient-specific 3D-printed mitral valves with moderate and severe MACs were placed in a left heart simulator. The velocity fields in the LV were acquired using time-resolved particle image velocimetry (TR-PIV) and compared to normal LV flow. The velocity fields were used to evaluate the temporal evolution of the vorticity fields and viscous energy loss in the LV. The presence of MAC disturbed the flow in the LV leading to markedly increased viscous energy losses. As the severity of MAC increased, the velocity of the inflow jet also increased causing significant perturbations to the normally-occurring vortex in the LV.

  13. The Annular Two-phase Flow on Rod Bundle: The Effects of Spacers

    NASA Astrophysics Data System (ADS)

    Kunugi, Tomoaki; Pham, Son; Kawara, Zensaku; Yokomine, Takehiko

    2013-11-01

    The annular two-phase flow on rod bundle keeps an important role in many heat exchange systems but our knowledge about it, especially the interaction between the liquid film flowing on the rods' surfaces and the spacers is very limited. This study is aimed to the investigation of how the spacer affects the disturbance waves of the flow in a 3 × 3 simulating BWR fuel rod bundle test section. Firstly, the characteristics of the disturbance waves at both upstream and downstream locations of the spacer were obtained by using reflected light arrangement with a high speed camera Phantom V7.1 (Vision Research Inc.) and a Nikon macro lens 105mm f/2.8. The data showed that the parameters such as frequency and circumferential coherence of the disturbance waves are strongly modified when they go through the spacer. Then, the observations at the locations right before and after the spacer were performed by using the back light arrangement with the same high speed camera and a Cassegrain optical system (Seika Cooperation). The obtained images at micro-scale of time and space provided the descriptions of the wavy interface behaviors right before and after the spacer as well as different droplets creation processes caused by the presence of this spacer.

  14. Wave Structure and Velocity Profiles in Downwards Gas-Liquid Annular Flows

    NASA Astrophysics Data System (ADS)

    Zadrazil, Ivan; Hewitt, Geoff; Matar, Omar; Markides, Christos

    2012-11-01

    A downwards flow of gas in the core of a vertical pipe, and of liquid in the annulus between the pipe wall and the gas phase is referred to as a ``downwards annular flow'' (DAF). DAFs are conventionally described in terms of short-lived, small-amplitude ``ripples,'' and large-amplitude, high-speed ``disturbances.'' We use a combination of Laser Induced Fluorescence (LIF), Particle Image and Tracking Velocimetry (PIV, PTV) to study DAFs. We demonstrate through these techniques that the liquid films become progressively more complex with increasing liquid Reynolds number (ReL), while a similar increase of complexity is observed for increasing gas Reynolds number (ReG). Disturbance waves are observed for low and high ReL, and ripples for intermediate ReL. Additionally, a high degree of rolling breakdown of disturbance waves is observed in falling films at the highest ReL, which is a source of bubble entrainment into the film body. Our results will comprise: (i) statistical data on film thickness, and (ii) wave frequency, velocity, wavelength. In addition, a qualitative (e.g. re-circulation zones) and quantitative (e.g. mean/rms velocity profiles) velocity characterisation of the film flows will be presented.

  15. Temporal evolution characteristics of an annular-mode gliding arc discharge in a vortex flow

    SciTech Connect

    Zhao, Tian-Liang; Liu, Jing-Lin; Li, Xiao-Song; Liu, Jin-Bao; Song, Yuan-Hong; Xu, Yong; Zhu, Ai-Min

    2014-05-15

    An annular-mode gliding arc discharge powered by a 50 Hz alternating current (ac) supply was studied in a vortex flow of dry and humid air. Its temporal evolution characteristics were investigated by electrical measurement, temporally resolved imaging, and temporally resolved optical emission spectroscopic measurements. Three discharge stages of arc-ignition, arc-gliding, and arc-extinction were clearly observed in each half-cycle of the discharge. During the arc-gliding stage, the intensity of light emission from the arc root at the cathode was remarkably higher than that at other areas. The spectral intensity of N{sub 2}(C{sup 3}Π{sub u}−B{sup 3}Π{sub g}) during the arc-ignition stage was much higher than that during the arc-gliding stage, which was contrary to the temporal evolutions of spectral intensities for N{sub 2}{sup +}(B{sup 2}Σ{sub u}{sup +}−X{sup 2}Σ{sub g}{sup +}) and OH(A{sup 2}Σ{sup +}−X{sup 2}Π{sub i}). Temporally resolved vibrational and rotational temperatures of N{sub 2} were also presented and decreased with increasing the water vapor content.

  16. Annular lichenoid dermatitis of youth--a further case in a 12-year-old girl.

    PubMed

    Kleikamp, Stefanie; Kutzner, Heinz; Frosch, Peter J

    2008-08-01

    Annular lichenoid dermatitis of youth was first described by Annessi et al. in 2003. Clinical criteria are persistent erythematous macules and annular lesions with a red-brown edge and a central hypopigmentation usually found on the flanks and groins of children and adolescents. Histologically, the disease is characterized by a lichenoid interface dermatitis with necrotic keratinocytes at the tip of the rete ridges. In our case a 12-year old girl developed annular red-brown macules with papules at the borders in an inframammary location. The histology of the lesion's border showed a lichenoid lymphocytic infiltrate with apoptotic keratinocytes at the tip of rete ridges. The lesions cleared with 0.03% tacrolimus ointment. Annular lichenoid dermatitis of youth is probably a new entity in the group of lichenoid dermatoses.

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

    SciTech Connect

    Myers, N.J.

    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.

  18. Predicting multidimensional annular flows with a locally based two-fluid model

    SciTech Connect

    Antal, S.P. Edwards, D.P.; Strayer, T.D.

    1998-06-01

    Annular flows are a well utilized flow regime in many industrial applications, such as, heat exchangers, chemical reactors and industrial process equipment. These flows are characterized by a droplet laden vapor core with a thin, wavy liquid film wetting the walls. The prediction of annular flows has been largely confined to one-dimensional modeling which typically correlates the film thickness, droplet loading, and phase velocities by considering the average flow conditions and global mass and momentum balances to infer the flow topology. In this paper, a methodology to predict annular flows using a locally based two-fluid model of multiphase flow is presented. The purpose of this paper is to demonstrate a modeling approach for annular flows using a multifield, multidimensional two-fluid model and discuss the need for further work in this area.

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

    EPA Science Inventory

    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)....

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

    SciTech Connect

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

    2015-11-15

    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.

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

    NASA Astrophysics Data System (ADS)

    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. Annular Pulse Shaping Technique for Large-Diameter Kolsky Bar Experiments on Concrete

    DTIC Science & Technology

    2014-10-01

    AFRL-RW-EG-TP-2014-005 Annular Pulse Shaping Technique for Large- Diameter Kolsky Bar Experiments on Concrete ...EXPERIMENTS ON CONCRETE N/A N/A 2502 9210 W0DT (1) Bradley E. Martin, RWMW (2) William F. Heard, Engineer Research and Development Center (3) Thomas...the dynamic compressive response of concretes . The purpose of implementing an annular pulse shaper design is to alleviate inertia-induced stresses in

  3. Nanoplasmonic imaging of latent fingerprints and identification of cocaine.

    PubMed

    Li, Kun; Qin, Weiwei; Li, Fan; Zhao, Xingchun; Jiang, Bowei; Wang, Kun; Deng, Suhui; Fan, Chunhai; Li, Di

    2013-10-25

    Search for traces: Aptamer-bound Au nanoparticles (Au NPs) were used to provide high-resolution dark-field microscopy images of latent fingerprints (LFPs) with level 2 and level 3 details. Furthermore, the cocaine-induced aggregation of Au NPs results in a true green-to-red color change of the scattered light, providing a quasi-quantative method to identify cocaine loadings in LFPs.

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

    NASA Astrophysics Data System (ADS)

    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.

  5. Capacitive micromachined ultrasonic transducers based on annular cell geometry for air-coupled applications.

    PubMed

    Na, Shuai; Chen, Albert I H; Wong, Lawrence L P; Li, Zhenhao; Macecek, Mirek; Yeow, John T W

    2016-09-01

    A novel design of an air-coupled capacitive micromachined ultrasonic transducer (CMUT) with annular cell geometry (annular CMUT) is proposed. Finite element analysis shows that an annular cell has a ratio of average-to-maximum displacement (RAMD) of 0.52-0.58 which is 58-76% higher than that of a conventional circular cell. The increased RAMD leads to a larger volume displacement which results in a 48.4% improved transmit sensitivity and 127.3% improved power intensity. Single-cell annular CMUTs were fabricated with 20-μm silicon plates on 13.7-μm deep and 1.35-mm wide annular cavities using the wafer bonding technique. The measured RAMD of the fabricated CMUTs is 0.54. The resonance frequency was measured to be 94.5kHz at 170-V DC bias. The transmit sensitivity was measured to be 33.83Pa/V and 25.85Pa/V when the CMUT was excited by a continuous wave and a 20-cycle burst, respectively. The receive sensitivity at 170-V DC bias was measured to be 7.7mV/Pa for a 20-cycle burst, and 15.0mV/Pa for a continuous incident wave. The proposed annular CMUT design demonstrates a significant improvement in transmit efficiency, which is an important parameter for air-coupled ultrasonic transducers.

  6. Jet Mixing and Emission Characteristics of Transverse Jets in Annular and Cylindrical Confined Crossflow

    NASA Technical Reports Server (NTRS)

    Bain, D. B.; Smith, C. E.; Holdeman, J. D.

    1995-01-01

    Three dimensional turbulent reacting CFD analyses were performed on transverse jets injected into annular and cylindrical (can) confined crossflows. The goal was to identify and assess mixing differences between annular and can geometries. The approach taken was to optimize both annular and can configurations by systematically varying orifice spacing until lowest emissions were achieved, and then compare the results. Numerical test conditions consisted of a jet-to-mainstream mass-flow ratio of 3.2 and a jet-to-mainstream momentum-flux ratio (J) of 30. The computational results showed that the optimized geometries had similar emission levels at the exit of the mixing section although the annular configuration did mix-out faster. For lowest emissions, the density correlation parameter (C = (S/H) square root of J) was 2.35 for the annular geometry and 3.5 for the can geometry. For the annular geometry, the constant was about twice the value seen for jet mixing at low mass-flow ratios (i.e., MR less than 0.5). For the can geometry, the constant was about 1 1/2 times the value seen for low mass-flow ratios.

  7. Design and Fabrication of Micro Hemispheric Shell Resonator with Annular Electrodes

    PubMed Central

    Wang, Renxin; Bai, Bing; Feng, Hengzhen; Ren, Ziming; Cao, Huiliang; Xue, Chenyang; Zhang, Binzhen; Liu, Jun

    2016-01-01

    Electrostatic driving and capacitive detection is widely used in micro hemispheric shell resonators (HSR). The capacitor gap distance is a dominant factor for the initial capacitance, and affects the driving voltage and sensitivity. In order to decrease the equivalent gap distance, a micro HSR with annular electrodes fabricated by a glassblowing method was developed. Central and annular cavities are defined, and then the inside gas drives glass softening and deformation at 770 °C. While the same force is applied, the deformation of the hemispherical shell is about 200 times that of the annular electrodes, illustrating that the deformation of the electrodes will not affect the measurement accuracy. S-shaped patterns on the annular electrodes and internal-gear-like patterns on the hemispherical shell can improve metal malleability and avoid metal cracking during glass expansion. An arched annular electrode and a hemispheric shell are demonstrated. Compared with HSR with a spherical electrode, the applied voltage could be reduced by 29%, and the capacitance could be increased by 39%, according to theoretical and numerical calculation. The surface roughness of glass after glassblowing was favorable (Rq = 0.296 nm, Ra = 0.217 nm). In brief, micro HSR with an annular electrode was fabricated, and its superiority was preliminarily confirmed. PMID:27897977

  8. Annular structures as intermediates in fibril formation of Alzheimer Abeta17-42.

    PubMed

    Zheng, Jie; Jang, Hyunbum; Ma, Buyong; Nussinov, Ruth

    2008-06-05

    We report all-atom molecular dynamics simulations of annular beta-amyloid (17-42) structures, single- and double-layered, in solution. We assess the structural stability and association force of Abeta annular oligomers associated through different interfaces, with a mutated sequence (M35A), and with the oxidation state (M35O). Simulation results show that single-layered annular models display inherent structural instability: one is broken down into linear-like oligomers, and the other collapses. On the other hand, a double-layered annular structure where the two layers interact through their C-termini to form an NC-CN interface (where N and C are the N and C termini, respectively) exhibits high structural stability over the simulation time due to strong hydrophobic interactions and geometrical constraints induced by the closed circular shape. The observed dimensions and molecular weight of the oligomers from atomic force microscopy (AFM) experiments are found to correspond well to our stable double-layered model with the NC-CN interface. Comparison with K3 annular structures derived from the beta 2-microglobulin suggests that the driving force for amyloid formation is sequence specific, strongly dependent on side-chain packing arrangements, structural morphologies, sequence composition, and residue positions. Combined with our previous simulations of linear-like Abeta, K3 peptide, and sup35-derived GNNQQNY peptide, the annular structures provide useful insight into oligomeric structures and driving forces that are critical in amyloid fibril formation.

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

    SciTech Connect

    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.

  10. Predicting Activation of Experiments Inside the Annular Core Research Reactor

    SciTech Connect

    Greenberg, Joseph Isaac

    2015-11-01

    The objective of this thesis is to create a program to quickly estimate the radioactivity and decay of experiments conducted inside of the Annular Core Research Reactor at Sandia National Laboratories and eliminate the need for users to write code. This is achieved by model the neutron fluxes in the reactor’s central cavity where experiments are conducted for 4 different neutron spectra using MCNP. The desired neutron spectrum, experiment material composition, and reactor power level are then input into CINDER2008 burnup code to obtain activation and decay information for every isotope generated. DREAD creates all of the files required for CINDER2008 through user selected inputs in a graphical user interface and executes the program for the user and displays the resulting estimation for dose rate at various distances. The DREAD program was validated by weighing and measuring various experiments in the different spectra and then collecting dose rate information after they were irradiated and comparing it to the dose rates that DREAD predicted. The program provides results with an average of 17% higher estimates than the actual values and takes seconds to execute.

  11. Acoustic modal analysis of a full-scale annular combustor

    NASA Technical Reports Server (NTRS)

    Karchmer, A. M.

    1982-01-01

    An acoustic modal decomposition of the measured pressure field in a full scale annular combustor installed in a ducted test rig is described. The modal analysis, utilizing a least squares optimization routine, is facilitated by the assumption of randomly occurring pressure disturbances which generate equal amplitude clockwise and counter-clockwise pressure waves, and the assumption of statistical independence between modes. These assumptions are fully justified by the measured cross spectral phases between the various measurement points. The resultant modal decomposition indicates that higher order modes compose the dominant portion of the combustor pressure spectrum in the range of frequencies of interest in core noise studies. A second major finding is that, over the frequency range of interest, each individual mode which is present exists in virtual isolation over significant portions of the spectrum. Finally, a comparison between the present results and a limited amount of data obtained in an operating turbofan engine with the same combustor is made. The comparison is sufficiently favorable to warrant the conclusion that the structure of the combustor pressure field is preserved between the component facility and the engine.

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

    NASA Technical Reports Server (NTRS)

    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.

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

    NASA Technical Reports Server (NTRS)

    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 nonuniformity, 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.

  14. Design and fabrication of a 40-MHz annular array transducer

    PubMed Central

    Ketterling, Jeffrey A.; Lizzi, Frederic L.; Aristizábal, Orlando; Turnbull, Daniel H.

    2006-01-01

    This paper investigates the feasibility of fabricating a 5-ring, focused annular array transducer operating at 40 MHz. The active piezoelectric material of the transducer was a 9-μm thick polyvinylidene fluoride (PVDF) film. One side of the PVDF was metallized with gold and forms the ground plane of the transducer. The array pattern of the transducer and electrical traces to each annulus were formed on a copper-clad polyimide film. The PVDF and polyimide were bonded with a thin layer of epoxy, pressed into a spherically curved shape, and then back filled with epoxy. A 5-ring transducer with equal area elements and 100 μm kerfs between annuli was fabricated and tested. The transducer had a total aperture of 6 mm and a geometric focus of 12 mm. The pulse/echo response from a quartz plate located at the geometric focus, two-way insertion loss (IL), complex impedance, electrical cross-talk, and lateral beamwidth were all measured for each annulus. The complex impedance data from each element were used to perform electrical matching and the measurements were repeated. After impedance matching, fc ≈ 36 MHz and BWs ranged from 31 to 39%. The ILs for the matched annuli ranged from −28 to −38 dB. PMID:16060516

  15. Reactor pulse repeatability studies at the annular core research reactor

    SciTech Connect

    DePriest, K.R.; Trinh, T.Q.; Luker, S. M.

    2011-07-01

    The Annular Core Research Reactor (ACRR) at Sandia National Laboratories is a water-moderated pool-type reactor designed for testing many types of objects in the pulse and steady-state mode of operations. Personnel at Sandia began working to improve the repeatability of pulse operations for experimenters in the facility. The ACRR has a unique UO{sub 2}-BeO fuel that makes the task of producing repeatable pulses difficult with the current operating procedure. The ACRR produces a significant quantity of photoneutrons through the {sup 9}Be({gamma}, n){sup 8}Be reaction in the fuel elements. The photoneutrons are the result of the gammas produced during fission and in fission product decay, so their production is very much dependent on the reactor power history and changes throughout the day/week of experiments in the facility. Because the photoneutrons interfere with the delayed-critical measurements required for accurate pulse reactivity prediction, a new operating procedure was created. The photoneutron effects at delayed critical are minimized when using the modified procedure. In addition, the pulse element removal time is standardized for all pulse operations with the modified procedure, and this produces less variation in reactivity removal times. (authors)

  16. Adipophilin expression in necrobiosis lipoidica, granuloma annulare, and sarcoidosis.

    PubMed

    Schulman, Joshua M; LeBoit, Philip E

    2015-03-01

    Necrobiosis lipoidica (NL), granuloma annulare (GA), and sarcoidosis usually are distinguished by clinical presentation and routine microscopy, but their distinction can sometimes be challenging. Historically, a clue to diagnosing NL or GA has been the identification of lipid droplets in the areas of altered collagen, but such studies have required fresh frozen tissue, making them impractical. Here, we present the first report of immunohistochemical staining to detect adipophilin, a membrane protein in lipid droplets, in NL (n = 12), GA (n = 19), sarcoidosis (n = 12), and, as a control for nonspecific tissue damage, nongranulomatous cutaneous necrosis (n = 13). Four patterns of labeling were identified: (1) extracellular, within zones of altered collagen; (2) both intracellular and extracellular, after the distribution of palisaded or scattered histiocytes; (3) intracellular, within clustered histiocytes; and (4) periadnexal. All cases of NL demonstrated pattern 1; nearly all cases of GA (18/19) demonstrated pattern 2; most sarcoidosis (10/12) demonstrated pattern 3; and nongranulomatous necrosis demonstrated either pattern 4 (6/13) or did not stain (6/13), confirming that the antibody to adipophilin did not adhere nonspecifically to the damaged tissue. An additional set of 3 biopsies with overlapping or partially sampled features of NL, GA, and/or sarcoidosis subsequently confirmed the potential utility of adipophilin staining in diagnostically challenging cases. We conclude that the pattern of adipophilin expression is a useful adjunct in the evaluation of granulomatous dermatitis.

  17. Flow Pressure Loss through Straight Annular Corrugated Pipes

    NASA Technical Reports Server (NTRS)

    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.

  18. Imbalanced superfluid state in an annular disk.

    PubMed

    Ye, Fei; Chen, Yan; Wang, Z D; Zhang, F C

    2009-09-02

    The imbalanced superfluid state of spin- 1/2 fermions with s-wave pairing is numerically studied by solving the Bogoliubov-de Gennes equation at zero temperature in an annular disk geometry with narrow radial width. Two distinct types of systems are considered. The first case may be relevant to heavy fermion superconductors, where magnetic field causes spin imbalance via Zeeman interaction and the system is studied in a grand canonical ensemble. As the magnetic field increases, the system is transformed from the uniform superfluid state to the Fulde-Ferrell-Larkin-Ovchinnikov state, and finally to the spin polarized normal state. The second case may be relevant to cold fermionic systems, where the number of fermions of each species is fixed as in a canonical ensemble. In this case, the ground state depends on the pairing strength. For weak pairing, the order parameter exhibits a periodic domain wall lattice pattern with a localized spin distribution at low spin imbalance, and a sinusoidally modulated pattern with extended spin distribution at high spin imbalance. For strong pairing, the phase separation between the superfluid state and polarized normal state is found to be preferable, while the increase of spin imbalance simply changes the ratio between them.

  19. Extraction of phenol in wastewater with annular centrifugal contactors.

    PubMed

    Xu, Jin-Quan; Duan, Wu-Hua; Zhou, Xiu-Zhu; Zhou, Jia-Zhen

    2006-04-17

    Solvent extraction is an effective way to treat and recover the phenolic compounds from the high content phenolic wastewater at present. The experimental study on treating the wastewater containing phenol has been carried out with QH-1extractant (the amine mixture) and annular centrifugal contactors. The distribution ratio of phenol was 108.6 for QH-1-phenol system. The mass-transfer process of phenol for the system was mainly controlled by diffusion. When the flow ratio (aqueous/organic) was changed from 1/1 to 4/1, the rotor speed was changed from 2500 to 4000 r/min, and the total flow of two phases was changed from 20 to 70 mL/min, the mass-transfer efficiency E of the single-stage centrifugal contactor was more than 95%. When the flow ratio was changed from 4.4/1 to 4.9/1, the rotor speed was 3000 r/min, and the total flow of two phases was changed from 43.0 to 47.0 mL/min, the extraction rate rho of the three-stage cascade was more than 99%. When 15% NaOH was used for stripping of phenol in QH-1, the stripping efficiency of the three-stage cascade was also more than 99% under the experimental conditions.

  20. Linear unsteady aerodynamic forces on vibrating annular cascade blades

    NASA Astrophysics Data System (ADS)

    Nagasaki, Taketo; Yamasaki, Nobuhiko

    2003-05-01

    The paper presents the formulation to compute numerically the unsteady aerodynamic forces on the vibrating annular cascade blades. The formulation is based on the finite volume method. By applying the TVD scheme to the linear unsteady calculations, the precise calculation of the peak of unsteady aerodynamic forces at the shock wave location like the delta function singularity becomes possible without empirical constants. As a further feature of the present paper, results of the present numerical calculation are compared with those of the double linearization theory (DLT), which assumes small unsteady and steady disturbances but the unsteady disturbances are much smaller than the steady disturbances. Since DLT requires far less computational resources than the present numerical calculation, the validation of DLT is quite important from the engineering point of view. Under the conditions of small steady disturbances, a good agreement between these two results is observed, so that the two codes are cross-validated. The comparison also reveals the limitation on the applicability of DLT.