WorldWideScience

Sample records for tunneling microscope studies

  1. A study of surface diffusion with the scanning tunneling microscope from fluctuations of the tunneling current

    Energy Technology Data Exchange (ETDEWEB)

    Manuel, Lozano [Iowa State Univ., Ames, IA (United States)

    1996-01-12

    The transport of atoms or molecules over surfaces has been an important area of study for several decades now, with its progress generally limited by the available experimental techniques to characterize the phenomena. A number of methods have been developed over the years to measure surface diffusion yet only very few systems have been characterized to this day mainly due to the physical limitations inherent in these available methods. Even the STM with its astonishing atomically-resolved images of the surface has been limited in terms of its capability to determine mass transport properties. This is because the STM is inherently a ``slow`` instrument, i.e., a finite time is needed for signal averaging in order to produce the image. A need exists for additional surface diffusion measurement techniques, ideally ones which are able to study varied systems and measure a wide range of diffusion rates. The STM (especially because of its highly local nature) presents itself as a promising tool to conduct dynamical studies if its poor time resolution during ``normal operation`` can somehow be overcome. The purpose of this dissertation is to introduce a new technique of using the STM to measure adatom mobility on surfaces -- one with a capacity to achieve excellent time resolution.

  2. A Student-Built Scanning Tunneling Microscope

    Science.gov (United States)

    Ekkens, Tom

    2015-01-01

    Many introductory and nanotechnology textbooks discuss the operation of various microscopes including atomic force (AFM), scanning tunneling (STM), and scanning electron microscopes (SEM). In a nanotechnology laboratory class, students frequently utilize microscopes to obtain data without a thought about the detailed operation of the tool itself.…

  3. Fiber coupled ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1997-01-01

    We report on a scanning tunneling microscope with a photoconductive gate in the tunneling current circuit. The tunneling tip is attached to a coplanar transmission line with an integrated photoconductive switch. The switch is illuminated through a fiber which is rigidly attached to the switch...... waveguide. The measurements show that the probe works as a transient voltage detector in contact and a capacitively coupled transient field detector in tunneling mode. We do not measure the transient voltage change in the ohmic tunneling current. In this sense, the spatial resolution for propagating...

  4. Photon scanning tunneling microscope in combination with a force microscope

    NARCIS (Netherlands)

    Moers, M.H.P.; Moers, M.H.P.; Tack, R.G.; van Hulst, N.F.; Bölger, B.; Bölger, B.

    1994-01-01

    The simultaneous operation of a photon scanning tunneling microscope with an atomic force microscope is presented. The use of standard atomic force silicon nitride cantilevers as near-field optical probes offers the possibility to combine the two methods. Vertical forces and torsion are detected

  5. Microscopic tunneling theory of long Josephson junctions

    DEFF Research Database (Denmark)

    Grønbech-Jensen, N.; Hattel, Søren A.; Samuelsen, Mogens Rugholm

    1992-01-01

    We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate that the detai......We present a numerical scheme for solving a nonlinear partial integro-differential equation with nonlocal time dependence. The equation describes the dynamics in a long Josephson junction modeled by use of the microscopic theory for tunneling between superconductors. We demonstrate...... that the detailed behavior of a solitonic mode (fluxon dynamics) in the junction is different from the results of the conventional perturbed sine-Gordon model....

  6. Scanning tunneling microscope assembly, reactor, and system

    Science.gov (United States)

    Tao, Feng; Salmeron, Miquel; Somorjai, Gabor A

    2014-11-18

    An embodiment of a scanning tunneling microscope (STM) reactor includes a pressure vessel, an STM assembly, and three spring coupling objects. The pressure vessel includes a sealable port, an interior, and an exterior. An embodiment of an STM system includes a vacuum chamber, an STM reactor, and three springs. The three springs couple the STM reactor to the vacuum chamber and are operable to suspend the scanning tunneling microscope reactor within the interior of the vacuum chamber during operation of the STM reactor. An embodiment of an STM assembly includes a coarse displacement arrangement, a piezoelectric fine displacement scanning tube coupled to the coarse displacement arrangement, and a receiver. The piezoelectric fine displacement scanning tube is coupled to the coarse displacement arrangement. The receiver is coupled to the piezoelectric scanning tube and is operable to receive a tip holder, and the tip holder is operable to receive a tip.

  7. Small-size low-temperature scanning tunnel microscope

    International Nuclear Information System (INIS)

    Al'tfeder, I.B.; Khajkin, M.S.

    1989-01-01

    A small-size scanning tunnel microscope, designed for operation in transport helium-filled Dewar flasks is described. The microscope design contains a device moving the pin to the tested sample surface and a piezoelectric fine positioning device. High vibration protection of the microscope is provided by its suspension using silk threads. The small-size scanning tunnel microscope provides for atomic resolution

  8. Design of a variable-temperature scanning tunneling microscope to study reaction intermediates in heterogeneous catalysis

    OpenAIRE

    Longwitz, Sarah R.; Brune, Harald

    2005-01-01

    Catalytic processes and in particular heterogeneous catalysis are vital for todays industry. However, many industrial catalytic processes require high temperatures and pressures to work efficiently. This stands in contrast to biological catalysts, which function under ambient temperatures and atmospheric pressures and excel in catalytic activity and selectivity. We may learn something from nature by studying the size-dependent reactivity of small metal particles resembling the active centers ...

  9. Measuring voltage transients with an ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1997-01-01

    We use an ultrafast scanning tunneling microscope to resolve propagating voltage transients in space and time. We demonstrate that the previously observed dependence of the transient signal amplitude on the tunneling resistance was only caused by the electrical sampling circuit. With a modified c......-gating photoconductive switch with a rigidly attached fiber, the probe is scanned without changing the probe characteristics. (C) 1997 American Institute of Physics.......We use an ultrafast scanning tunneling microscope to resolve propagating voltage transients in space and time. We demonstrate that the previously observed dependence of the transient signal amplitude on the tunneling resistance was only caused by the electrical sampling circuit. With a modified...... circuit, where the tunneling tip is directly connected to the current amplifier of the scanning tunneling microscope, this dependence is eliminated. Ail results can be explained with coupling through the geometrical capacitance of the tip-electrode junction. By illuminating the current...

  10. Control circuit for a scanning tunneling microscope

    Science.gov (United States)

    Munoz, Raúl C.; Villagra, Paolo; Kremer, Germán; Moraga, Luis; Vidal, Guillermo

    1998-09-01

    We have successfully built and tested a circuit designed to control a piezoelectric tube scanner having the standard single inner-electrode quartered outer-electrode configuration, using digital-to-analog (D/A) converters commercially available. To avoid noise associated with the PC, the signals transmitted by the D/A channels to the control electronics are received by instrumentation amplifiers INA 105 at the control circuit, providing 86 dB common mode rejection, thereby over four orders of magnitude of immunity to common mode noise. To prevent ground loops in the communication between the control electronics and the analog-to-digital (A/D) converters, a novel approach was used. The signals sent by the control electronics to the A/D converters were transmitted via isolation amplifiers ISO 122 followed by a 10 kHz Sallen-Key low pass filter incorporated at each output of the control circuit, providing galvanic isolation between the control electronics and the PC, thereby eliminating ground loops. The control circuit was designed to allow analog as well as digital feedback, selectable via a toggle switch. The design also incorporates the possibility of using two independent external signals to modulate the polarization of the sample and two independent external signals to modulate the piezoelectric transducer drive along the Z direction. It also incorporates the possibility of electronically canceling the slope that might occur while scanning due to the sample being tilted along the X axis (fast scan direction) and/or along the Y axis (slow scan direction). The circuit was tested using two 12 bit A/D-D/A converters DAS 1602 to control the scanner of a scanning tunneling microscope, with a home-built scanning head, electrometer, and preamplifier. With the complete system in operation but in the absence of tunneling current, the electrometer exhibits a current noise under 3 pA rms and a response time of 30 μs to a step input current, a performance that compares well

  11. Single-atom contacts with a scanning tunnelling microscope

    International Nuclear Information System (INIS)

    Kroeger, J; Neel, N; Sperl, A; Wang, Y F; Berndt, R

    2009-01-01

    The tip of a cryogenic scanning tunnelling microscope is used to controllably contact single atoms adsorbed on metal surfaces. The transition between tunnelling and contact is gradual for silver, while contact to adsorbed gold atoms is abrupt. The single-atom junctions are stable and enable spectroscopic measurements of, e.g., the Abrikosov-Suhl resonance of single Kondo impurities.

  12. Transient measurements with an ultrafast scanning tunneling microscope

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1998-01-01

    We use a photoconductively gated ultrafast scanning tunneling microscope to resolve laser-induced transients on transmission lines and photoconductors. The photoconductive switch on the tunneling probe is illuminated through a rigidly attached fiber. The use of the fiber enables us to scan across...... the transmission line while the change in delay time between pump beam (on the sample) and probe beam (on the probe) provides the temporal information. The investigated photoconductor sample is a low-temperature-grown GaAs layer placed on a sapphire substrate with a thin, semitransparent gold layer. In tunneling...... mode the probe is sensitive to laser-induced field changes in the semiconductor layer. Laser-induced transient signals of 2.2 ps widths are detected. As for the transmission lines, the signals can be explained by a capacitive coupling across the tunneling gap....

  13. Compact scanning tunneling microscope for spin polarization measurements.

    Science.gov (United States)

    Kim, Seong Heon; de Lozanne, Alex

    2012-10-01

    We present a design for a scanning tunneling microscope that operates in ultrahigh vacuum down to liquid helium temperatures in magnetic fields up to 8 T. The main design philosophy is to keep everything compact in order to minimize the consumption of cryogens for initial cool-down and for extended operation. In order to achieve this, new ideas were implemented in the design of the microscope body, dewars, vacuum chamber, manipulators, support frame, and vibration isolation. After a brief description of these designs, the results of initial tests are presented.

  14. Near-field optical microscopy with a scanning tunneling microscope

    International Nuclear Information System (INIS)

    Barbara, A.; Lopez-Rios, T.; Quemerais, P.

    2005-01-01

    A homemade apertureless near-field optical microscope using a scanning tunneling microscope (STM) is described. The experimental set-up simultaneously provides optical and topographic images of the sample. Technical details and features of the set-up are presented, together with results demonstrating the sub-wavelength resolution achieved as well as its sensitivity to dielectric contrasts. We show that the use of a STM permits to precisely control very small distances between the tip and the sample which is a great advantage to excite localized optical resonances between the tip and the surface

  15. Distinction of nuclear spin states with the scanning tunneling microscope.

    Science.gov (United States)

    Natterer, Fabian Donat; Patthey, François; Brune, Harald

    2013-10-25

    We demonstrate rotational excitation spectroscopy with the scanning tunneling microscope for physisorbed H(2) and its isotopes HD and D(2). The observed excitation energies are very close to the gas phase values and show the expected scaling with the moment of inertia. Since these energies are characteristic for the molecular nuclear spin states we are able to identify the para and ortho species of hydrogen and deuterium, respectively. We thereby demonstrate nuclear spin sensitivity with unprecedented spatial resolution.

  16. Optical and electrical characterization at the nanoscale with a transparent probe of a scanning tunnelling microscope

    International Nuclear Information System (INIS)

    Sychugov, Ilya; Omi, Hiroo; Murashita, Tooru; Kobayashi, Yoshihiro

    2009-01-01

    A new type of scanning probe microscope, combining features of the scanning tunnelling microscope, the scanning tunnelling luminescence microscope with a transparent probe and the aperture scanning near-field optical microscope, is described. Proof-of-concept experiments were performed under ultrahigh vacuum conditions at varying temperature on GaAs/AlAs heterostructures.

  17. Nanofabrication with the Scanning Tunneling Microscope

    Energy Technology Data Exchange (ETDEWEB)

    Shedd, G.M.; Russell, P.E.

    1988-12-01

    The Precision Engineering Center has recently begun a research program into applications of STM to Nanotechnology. Few tools permit humans to control events and processes at the manometer level, and of those, the STM is the most well-suited to the task. A versatile new ultra-high-vacuum (UHV) STM is being built to study the use of STM for the manipulation of nanometer-scale particles. Part of the STM`s usefulness will be due to its being positioned directly beneath the focused ion beam (FIB). The interface of the STM with the FIB will allow the STM to take advantage of the FIB for long-range imaging and as a particle source; the FIB can in turn use the STM for in situ, high-resolution imaging of micromachined features.

  18. Scanning tunneling microscope stimulated oxidation of silicon (100) surfaces

    Science.gov (United States)

    Fay, P.; Brockenbrough, R. T.; Abeln, G.; Scott, P.; Agarwala, S.; Adesida, I.; Lyding, J. W.

    1994-06-01

    The chemical modification of n- and p-type hydrogen-passivated Si(100) surfaces by a scanning tunneling microscope (STM) is reported. The modified areas have been examined with STM, Auger electron spectroscopy, scanning electron microscopy, and atomic force microscopy. Comparison of these characterization techniques indicates the features are both chemical and topographic in nature and are the result of local oxidation of the substrate. In addition, pattern transfer for the defined regions has been demonstrated with both thermal oxidation and HBr reactive-ion etching.

  19. Electric field effects in scanning tunneling microscope imaging

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Quaade, Ulrich; Grey, Francois

    1998-01-01

    We present a high-voltage extension of the Tersoff-Hamann theory of scanning tunneling microscope (STM) images, which includes the effect of the electric field between the tip and the sample. The theoretical model is based on first-principles electronic structure calculations and has no adjustable...... parameters. We use the method to calculate theoretical STM images of the monohydrate Si(100)-H(2x1) surface with missing hydrogen defects at -2V and find an enhanced corrugation due to the electric field, in good agreement with experimental images....

  20. Near-field study with a photon scanning tunneling microscope: Comparison between dielectric nanostructure and metallic nanostructure

    International Nuclear Information System (INIS)

    Mahmoud, Mahmoud Youcef; Bassou, Ghaouti; Salomon, Laurant; Chekroun, Z.; Djamai, Nesrine

    2007-01-01

    Scanning near-field optical microscopy (SNOM) integrates standard optical methods with scanning probe microscopy (SPM) techniques allowing to collect optical information with resolution well beyond the diffraction limit. We study the influence on image formation of several parameters in scanning near-field microscopy. The numerical calculations have been carried out using the differential method. We investigate a 2D-PSTM configuration with a dielectric rectangular object. We will focus on the collection type SNOM in a constant height scanning mode. Various oscillation patterns are observed from both sides of the nanostructure, which we interpret as interference between the diffracted waves scattered by the nanostructure (with the components of the wave vector parallel to the surface) and the evanescent incident wave above the surface. Using an optical near-field analysis and by calculating the electric field intensity distribution, we investigate the probe-sample distance effect. It is found that the distribution of the intensity related to the electric field is depending on sample-probe distance. We noticed the loss of details in the image and the presence of dramatic oscillations. Also, both of the polarization state of the illuminating light effect and the angle of incidence are investigated. We conclude that a differential method provides physical insight into the main features of the different images

  1. Near-field study with a photon scanning tunneling microscope: Comparison between dielectric nanostructure and metallic nanostructure

    Energy Technology Data Exchange (ETDEWEB)

    Mahmoud, Mahmoud Youcef [Laboratoire d' elaboration et caracterisation des materiaux, Groupe de Microscopie et Microanalyse, Universite Djilali Liabes de Sidi Bel-Abbes, Faculte des sciences (Algeria)], E-mail: mahmoudhamoud@yahoo.com; Bassou, Ghaouti [Laboratoire d' elaboration et caracterisation des materiaux, Groupe de Microscopie et Microanalyse, Universite Djilali Liabes de Sidi Bel-Abbes, Faculte des sciences (Algeria); Laboratoire de Physique (LPUB), CNRS UMR 5027, Groupe d' Optique de Champ Proche, Faculte des Sciences Mirande, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47 870, 21078 Dijon Cedex (France); Salomon, Laurant [Laboratoire de Physique (LPUB), CNRS UMR 5027, Groupe d' Optique de Champ Proche, Faculte des Sciences Mirande, Universite de Bourgogne, 9 Avenue Alain Savary, BP 47 870, 21078 Dijon Cedex (France); Chekroun, Z. [Laboratoire d' elaboration et caracterisation des materiaux, Groupe de Microscopie et Microanalyse, Universite Djilali Liabes de Sidi Bel-Abbes, Faculte des sciences (Algeria); Djamai, Nesrine [Laboratoire de telecommunications et de traitement numerique du signal (LTTNS), Universite Djilali Liabes de Sidi Bel-Abbes, Faculte des sciences de l' ingenieur, Departement d' electronique (Algeria)

    2007-08-25

    Scanning near-field optical microscopy (SNOM) integrates standard optical methods with scanning probe microscopy (SPM) techniques allowing to collect optical information with resolution well beyond the diffraction limit. We study the influence on image formation of several parameters in scanning near-field microscopy. The numerical calculations have been carried out using the differential method. We investigate a 2D-PSTM configuration with a dielectric rectangular object. We will focus on the collection type SNOM in a constant height scanning mode. Various oscillation patterns are observed from both sides of the nanostructure, which we interpret as interference between the diffracted waves scattered by the nanostructure (with the components of the wave vector parallel to the surface) and the evanescent incident wave above the surface. Using an optical near-field analysis and by calculating the electric field intensity distribution, we investigate the probe-sample distance effect. It is found that the distribution of the intensity related to the electric field is depending on sample-probe distance. We noticed the loss of details in the image and the presence of dramatic oscillations. Also, both of the polarization state of the illuminating light effect and the angle of incidence are investigated. We conclude that a differential method provides physical insight into the main features of the different images.

  2. Fully low voltage and large area searching scanning tunneling microscope

    International Nuclear Information System (INIS)

    Pang, Zongqiang; Wang, Jihui; Lu, Qingyou

    2009-01-01

    We present a novel scanning tunneling microscope (STM), which allows the tip to travel a large distance (millimeters) on the sample and take images (to find microscopic targets) anywhere it reaches without losing atomic resolution. This broad range searching capability, together with the coarse approach and scan motion, is all done with only one single piezoelectric tube scanner as well as with only low voltages (<15 V). Simple structure, low interference and high precision are thus achieved. To this end, a pillar and a tube scanner are mounted in parallel on a base with one ball glued on the pillar top and two balls glued on the scanner top. These three balls form a narrow triangle, which supports a triangular slider piece. By inertial stepping, the scanner can move the slider toward the pillar (coarse approach) or rotate the slider about the pillar (travel along sample surface). Since all the stepping motions are driven by the scanner's lateral bending which is large per unit voltage, high voltages are unnecessary. The technology is also applicable to scanning force microscopes (SFM) such as atomic force microscopes (AFM), etc

  3. A compact combined ultrahigh vacuum scanning tunnelling microscope (UHV STM) and near-field optical microscope

    International Nuclear Information System (INIS)

    Woolley, R A J; Hayton, J A; Cavill, S; Ma, Jin; Beton, P H; Moriarty, P

    2008-01-01

    We have designed and constructed a hybrid scanning near-field optical microscope (SNOM)–scanning tunnelling microscope (STM) instrument which operates under ultrahigh vacuum (UHV) conditions. Indium tin oxide (ITO)-coated fibre-optic tips capable of high quality STM imaging and tunnelling spectroscopy are fabricated using a simple and reliable method which foregoes the electroless plating strategy previously employed by other groups. The fabrication process is reproducible, producing robust tips which may be exchanged under UHV conditions. We show that controlled contact with metal surfaces considerably enhances the STM imaging capabilities of fibre-optic tips. Light collection (from the cleaved back face of the ITO-coated fibre-optic tip) and optical alignment are facilitated by a simple two-lens arrangement where the in-vacuum collimation/collection lens may be adjusted using a slip-stick motor. A second in-air lens focuses the light (which emerges from the UHV system as a parallel beam) onto a cooled CCD spectrograph or photomultiplier tube. The application of the instrument to combined optical and electronic spectroscopy of Au and GaAs surfaces is discussed

  4. Design and performance of a beetle-type double-tip scanning tunneling microscope

    International Nuclear Information System (INIS)

    Jaschinsky, Philipp; Coenen, Peter; Pirug, Gerhard; Voigtlaender, Bert

    2006-01-01

    A combination of a double-tip scanning tunneling microscope with a scanning electron microscope in ultrahigh vacuum environment is presented. The compact beetle-type design made it possible to integrate two independently driven scanning tunneling microscopes in a small space. Moreover, an additional level for coarse movement allows the decoupling of the translation and approach of the tunneling tip. The position of the two tips can be controlled from the millimeter scale down to 50 nm with the help of an add-on electron microscope. The instrument is capable of atomic resolution imaging with each tip

  5. A variable-temperature scanning tunneling microscope capable of single-molecule vibrational spectroscopy

    International Nuclear Information System (INIS)

    Stipe, B.C.; Rezaei, M.A.; Ho, W.

    1999-01-01

    The design and performance of a variable-temperature scanning tunneling microscope (STM) is presented. The microscope operates from 8 to 350 K in ultrahigh vacuum. The thermally compensated STM is suspended by springs from the cold tip of a continuous flow cryostat and is completely surrounded by two radiation shields. The design allows for in situ dosing and irradiation of the sample as well as for the exchange of samples and STM tips. With the STM feedback loop off, the drift of the tip-sample spacing is approximately 0.001 Angstrom/min at 8 K. It is demonstrated that the STM is well-suited for the study of atomic-scale chemistry over a wide temperature range, for atomic-scale manipulation, and for single-molecule inelastic electron tunneling spectroscopy (IETS). copyright 1999 American Institute of Physics

  6. Nanoscale coupling of photons to vibrational excitation of Ag nanoparticle 2D array studied by scanning tunneling microscope light emission spectroscopy.

    Science.gov (United States)

    Katano, Satoshi; Toma, Koji; Toma, Mana; Tamada, Kaoru; Uehara, Yoichi

    2010-11-28

    Scanning tunneling microscope light emission (STM-LE) spectroscopy has been utilized to elucidate the luminescence phenomena of Ag nanoparticles capped with myristate (myristate-capped AgNP) and 2-methyl-1-propanethiolate (C(4)S-capped AgNP) on the dodecanethiol-precovered Au substrate. The STM imaging revealed that myristate-capped AgNPs form an ordered hexagonal array whereas C(4)S-capped AgNPs show imperfect ordering, indicating that a shorter alkyl chain of C(4)S-capped AgNP is not sufficient to form rigid interdigitation. It should be noted that such a nanoparticle ordering affects the luminescence properties of the Ag nanoparticle. We found that the STM-LE is only detected from the Ag nanoparticles forming the two-dimensional superlattice. This indicates that the STM-LE of the Ag nanoparticle is radiated via the collective excitation of the local surface plasmon resonance (LSPR) spread over the Ag nanoparticles. Note that the STM-LE spectra of the Ag nanoparticles exhibit spike-like peaks superimposed on the broad light emission peak. Using Raman spectroscopy, we concluded that the spike-like structure appearing in the STM-LE spectra is associated with the vibrational excitation of the molecule embedded between Ag nanoparticles.

  7. High Pressure Scanning Tunneling Microscopy Studies of Adsorbate Structure and Mobility during Catalytic Reactions. Novel Design of an Ultra High Pressure, High Temperature Scanning Tunneling Microscope System for Probing Catalytic Conversions

    International Nuclear Information System (INIS)

    Tang, David Chi-Wai

    2005-01-01

    The aim of the work presented therein is to take advantage of scanning tunneling microscope's (STM) capability for operation under a variety of environments under real time and at atomic resolution to monitor adsorbate structures and mobility under high pressures, as well as to design a new generation of STM systems that allow imaging in situ at both higher pressures (35 atm) and temperatures (350 C). The design of a high pressure, high temperature scanning tunneling microscope system, that is capable of monitoring reactions in situ at conditions from UHV and ambient temperature up to 1 atm and 250 C, is briefly presented along with vibrational and thermal analysis, as this system serves as a template to improve upon during the design of the new ultra high pressure, high temperature STM. Using this existing high pressure scanning tunneling microscope we monitored the co-adsorption of hydrogen, ethylene and carbon dioxide on platinum (111) and rhodium (111) crystal faces in the mTorr pressure range at 300 K in equilibrium with the gas phase. During the catalytic hydrogenation of ethylene to ethane in the absence of CO the metal surfaces are covered by an adsorbate layer that is very mobile on the time scale of STM imaging. We found that the addition of CO poisons the hydrogenation reaction and induces ordered structures on the single crystal surfaces. Several ordered structures were observed upon CO addition to the surfaces pre-covered with hydrogen and ethylene: a rotated (√19 x √19)R23.4 o on Pt(111), and domains of c(4 x 2)-CO+C 2 H 3 , previously unobserved (4 x 2)-CO+3C 2 H 3 , and (2 x 2)-3CO on Rh(111). A mechanism for CO poisoning of ethylene hydrogenation on the metal single crystals was proposed, in which CO blocks surface metal sites and reduces adsorbate mobility to limit adsorption and reaction rate of ethylene and hydrogen. In order to observe heterogeneous catalytic reactions that occur well above ambient pressure and temperature that more closely

  8. Electron microscope studies

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-07-01

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

  9. Electron microscope studies

    International Nuclear Information System (INIS)

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

    1992-01-01

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

  10. Transient measurements with an ultrafast scanning tunneling microscope on semiconductor surfaces

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1998-01-01

    We demonstrate: the use of an ultrafast scanning tunneling microscope on a semiconductor surface. Laser-induced transient signals with 1.8 ps rise time are detected, The investigated sample is a low-temperature grown GaAs layer plated on a sapphire substrate with a thin gold layer that serves as st...... by the nonuniform carrier density created by the absorption of the light (photo Dember effect). The transient depends in sign and in shape on the direction of optical excitation. This signal is the dominating transient in tunneling mode. The signals are explained by a capacitive coupling across the tunneling gap...

  11. High Pressure Scanning Tunneling Microscopy Studies of AdsorbateStructure and Mobility during Catalytic Reactions: Novel Design of anUltra High Pressure, High Temperature Scanning Tunneling MicroscopeSystem for Probing Catalytic Conversions

    Energy Technology Data Exchange (ETDEWEB)

    Tang, David Chi-Wai [Univ. of California, Berkeley, CA (United States)

    2005-05-16

    The aim of the work presented therein is to take advantage of scanning tunneling microscope’s (STM) capability for operation under a variety of environments under real time and at atomic resolution to monitor adsorbate structures and mobility under high pressures, as well as to design a new generation of STM systems that allow imaging in situ at both higher pressures (35 atm) and temperatures (350 °C).

  12. Quasi interference of perpendicularly polarized guided modes observed with a photon scanning tunneling microscope

    NARCIS (Netherlands)

    Balistreri, M.L.M.; Driessen, A.; Korterik, Jeroen P.; Kuipers, L.; van Hulst, N.F.

    2000-01-01

    The simultaneous detection of TE- as well as TM-polarized light with a photon scanning tunneling microscope leads to a quasi- interference pattern of these mutually perpendicular polarized fields. This interference pattern has been observed in the optical field distribution as a function of both

  13. A new method to detect geometrical information by the tunneling microscope

    DEFF Research Database (Denmark)

    Tasaki, S.; Levitan, J.; Mygind, Jesper

    1997-01-01

    A new method for the detection of the geometrical information by the scanning tunneling microscope is proposed. In addition to the bias voltage, a small ac modulation is applied. The nonlinear dependence of the transmission coefficient on the applied voltage is used to generate harmonics. The ratio...

  14. Measurements with an ultrafast scanning tunnelling microscope on photoexcited semiconductor layers

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Jensen, Jacob Riis; Hvam, Jørn Märcher

    1998-01-01

    Summary form only given. We demonstrate the use of a ultrafast scanning tunnelling microscopes (USTM) for detecting laser-induced field transients on semiconductor layers. In principle, the instrument can detect transient field changes thus far observed as far-field THz radiation in the near...

  15. Observation of a Ag protrusion on a Ag2S island using a scanning tunneling microscope

    Directory of Open Access Journals (Sweden)

    Takeo Ohno

    2015-01-01

    Full Text Available A silver sulfide (Ag2S island as an ionic conductor in resistive switching memories was formed and a protrusion of silver from the Ag2S formed by an electrochemical reaction was observed using a scanning tunneling microscope.

  16. A simple, ultrahigh vacuum compatible scanning tunneling microscope for use at variable temperatures

    NARCIS (Netherlands)

    Mugele, Friedrich Gunther; Kloos, Ch.; Leiderer, P.; Moller, R.

    1996-01-01

    We present the construction of a very compact scanning tunneling microscope (STM) which can be operated at temperatures between 4 and 350 K. The tip and a tiny tip holder are the only movable parts, whereas the sample and the piezoscanner are rigidly attached to the body of the STM. This leads to an

  17. Selective scanning tunneling microscope light emission from rutile phase of VO2.

    Science.gov (United States)

    Sakai, Joe; Kuwahara, Masashi; Hotsuki, Masaki; Katano, Satoshi; Uehara, Yoichi

    2016-09-28

    We observed scanning tunneling microscope light emission (STM-LE) induced by a tunneling current at the gap between an Ag tip and a VO2 thin film, in parallel to scanning tunneling spectroscopy (STS) profiles. The 34 nm thick VO2 film grown on a rutile TiO2 (0 0 1) substrate consisted of both rutile (R)- and monoclinic (M)-structure phases of a few 10 nm-sized domains at room temperature. We found that STM-LE with a certain photon energy of 2.0 eV occurs selectively from R-phase domains of VO2, while no STM-LE was observed from M-phase. The mechanism of STM-LE from R-phase VO2 was determined to be an interband transition process rather than inverse photoemission or inelastic tunneling processes.

  18. Restoration of images from the scanning-tunneling microscope

    Science.gov (United States)

    Kokaram, A. C.; Persad, N.; Lasenby, J.; Fitzgerald, W. J.; McKinnon, A.; Welland, M.

    1995-08-01

    During the acquisition of an image from any probe microscope instrument, various noise sources cause distortion in the observed image. It is often the case that impulsive disturbances cause bright groups of pixels to replace the actual image data in these locations. Furthermore, the images from a probe microscope show some amount of blurring caused both by the instrument function and the material properties. In almost all image-processing applications it is important to remove any impulsive distortion that may be present before deblurring can be attempted. We give a technique for detecting these impulses and reconstructing the image. This technique is superior to the standard global application of median filters for the case considered. The reconstruction is limited only to the affected regions and therefore results in a much sharper and more meaningful image. With the assumption of Gaussian blur it is then possible to propose several different deblurring methodologies. We present a novel Wiener-filter deblurring implementation and compare it to both maximum-entropy and Richardson-Lucy deblurring.

  19. Electron microscope studies

    International Nuclear Information System (INIS)

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

    1991-01-01

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

  20. Electron microscope studies

    Energy Technology Data Exchange (ETDEWEB)

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

    1991-06-01

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

  1. Electron microscope studies

    International Nuclear Information System (INIS)

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

    1990-01-01

    Our laboratory has made significant progress this year in devising improved electron-optical systems, in studying invertebrate hemoglobins with the STEM, and in achieving a workable sub-angstrom STEM. Our goal in electron optics is to improve resolution by producing spherical and chromatic aberration coefficients with signs opposite those of magnetic lenses. We have progressed toward this goal through calculations that explore the addition of electrodes to electron mirrors to reduce these two geometric aberrations and by devising a beam separation system that won't introduce asymmetrical aberrations. Some promising new designs of magnetic lenses for SEM applications have also been investigated. We have continued our exploration of the quaternary structure of the invertebrate hemoglobins and are now among the top laboratories in this area of expertise. In addition, we have overcome many of our electronic difficulties on the sub-angstrom STEM and have made significant progress toward achieving an operational system. The addition of an IBM RISC-6000 workstation to our lab has significantly increased our image processing capabilities

  2. The tunnel effect and their more important application: The microscope of quantum tunneling

    International Nuclear Information System (INIS)

    Alvarez M, L.

    1999-01-01

    Thanks to a donation made by the Volunteered Japanese JICA Program, the University National Headquarters Manizales, in particular the group of Physics of the Plasma, it has acquired a equipment where it is possible to combine several microscopy techniques: STM (scanning tunneling microscopy), AFM (atomic forced microscopy), MFM (magnetic forced microscopy) and LFM (lateral forced microscopy). These techniques group under the generic name of probe microscopy (SPM). The objective of this article is to offer a basic understanding to the whole university community on one of the previously mentioned techniques, STM, with the goal of generating future collaborations among the diverse investigators of the Headquarters. In the first one it leaves it explains the physical phenomenon in which the STM is based, then it is exposed in a brief way the operation of the same one and finally some of its applications are mentioned

  3. Construction of a sub-Kelvin ultrahigh vacuum scanning tunneling microscope in high magnetic field

    Science.gov (United States)

    Ham, Ungdon

    A sub-Kelvin ultrahigh vacuum (UHV) scanning tunneling microscope (STM) high magnetic field has been designed and constructed, and has been tested at ˜ 1K and in high magnetic field up to 9 teslas. A four-chamber ultrahigh vacuum system creates reliable environment for tip and sample preparation, surface characterization, and exchanging samples, tips, and evaporating materials. The pressure of chambers is in the low 10 -11 torr range. Various metal atoms and organic molecules can be deposited at room or low temperatures by home-made evaporators. The whole system is mounted on a custom vibration isolation table. A bottom loading ultrahigh vacuum compatible helium-3 cryostat with 9 tesla superconducting magnet is mounted above the vacuum chambers. The Besocke type scanner is modified to meet the requirements of sub-Kelvin temperature and high magnetic field. The scanner is mounted at the bottom of the cryostat insert, which is driven by a bellows type linear translator. The scanner is at the center of the superconducting magnet for measurements at sub-Kelvin temperatures in high magnetic field. With the scanner at the bottom 25 K position, tips and samples can be exchanged. The cryostat has two separate helium-4 reservoirs for the non-bakeable NbTi superconducting magnet and UHV space. The inner liquid helium reservoir provides a low radiation heat leak to the scanner at sub-Kelvin temperatures. Two layers of aluminum shields make use of the enthalpy of the cold He-4 vapor for radiation shielding. Detachable 25 K thermal anchoring to the STM scanner cools down the STM scanner very effectively. With 15 ml liquid helium-3, a holding time of more than 50 hours at 0.4 K base temperature was obtained, and it will be increased some more with new modifications. Combined manipulating single atoms and molecules to make artificial nanometer size structures, with high resolution spectroscopy techniques of high resolution inelastic tunneling spectroscopy and spin

  4. Scanning tunnelling microscope light emission: Finite temperature current noise and over cut-off emission.

    Science.gov (United States)

    Kalathingal, Vijith; Dawson, Paul; Mitra, J

    2017-06-14

    The spectral distribution of light emitted from a scanning tunnelling microscope junction not only bears its intrinsic plasmonic signature but is also imprinted with the characteristics of optical frequency fluc- tuations of the tunnel current. Experimental spectra from gold-gold tunnel junctions are presented that show a strong bias (V b ) dependence, curiously with emission at energies higher than the quantum cut-off (eV b ); a component that decays monotonically with increasing bias. The spectral evolution is explained by developing a theoretical model for the power spectral density of tunnel current fluctuations, incorporating finite temperature contribution through consideration of the quantum transport in the system. Notably, the observed decay of the over cut-off emission is found to be critically associated with, and well explained in terms of the variation in junction conductance with V b . The investigation highlights the scope of plasmon-mediated light emission as a unique probe of high frequency fluctuations in electronic systems that are fundamental to the electrical generation and control of plasmons.

  5. Fiber optic light collection system for scanning-tunneling-microscope-induced light emission.

    Science.gov (United States)

    Watkins, Neil J; Long, James P; Kafafi, Zakya H; Mäkinen, Antti J

    2007-05-01

    We report a compact light collection scheme suitable for retrofitting a scanning tunneling microscope (STM) for STM-induced light emission experiments. The approach uses a pair of optical fibers with large core diameters and high numerical apertures to maximize light collection efficiency and to moderate the mechanical precision required for alignment. Bench tests indicate that efficiency reduction is almost entirely due to reflective losses at the fiber ends, while losses due to fiber misalignment have virtually been eliminated. Photon-map imaging with nanometer features is demonstrated on a stepped Au(111) surface with signal rates exceeding 10(4) counts/s.

  6. Development of a scanning tunneling microscope combined with a synchrotron radiation light source

    International Nuclear Information System (INIS)

    Hasegawa, Yukio; Okuda, Taichi; Eguchi, Toyoaki; Matsushima, Takeshi; Harasawa, Ayumi; Akiyama, Kotone; Kinoshita, Toyohiko

    2005-01-01

    We have developed a scanning tunneling microscope (STM) combined with a synchrotron-radiation light source (SR-STM) aiming at elemental analysis in a spatial resolution of STM. Using SR-STM atomically resolved STM images under the irradiation and also X-ray adsorption spectra clearly showing an adsorption edge of a substrate were successfully obtained by detecting photo-emitted electrons with the STM tip. In order to focus the probing area of the photo-induced current, a glass-coated metal tip sharpened with focused ion beam was used as a probe. The present situation and prospects of the instrument are discussed in this review. (author)

  7. Visible Light Emission from Atomic Scale Patterns Fabricated by the Scanning Tunneling Microscope

    DEFF Research Database (Denmark)

    Thirstrup, C.; Sakurai, M.; Stokbro, Kurt

    1999-01-01

    Scanning tunneling microscope (STM) induced light emission from artificial atomic scale structures comprising silicon dangling bonds on hydrogen-terminated Si(001) surfaces has been mapped spatially and analyzed spectroscopically in the visible spectral range. The light emission is based on a novel...... mechanism involving optical transitions between a tip state and localized states on the sample surface. The wavelength of the photons can be changed by the bias voltage of the STM. The spatial resolution of the photon maps is as good as that of STM topographic images and the photons are emitted from...

  8. Magnetic fingerprint of individual Fe4 molecular magnets under compression by a scanning tunnelling microscope

    Science.gov (United States)

    Burgess, Jacob A. J.; Malavolti, Luigi; Lanzilotto, Valeria; Mannini, Matteo; Yan, Shichao; Ninova, Silviya; Totti, Federico; Rolf-Pissarczyk, Steffen; Cornia, Andrea; Sessoli, Roberta; Loth, Sebastian

    2015-09-01

    Single-molecule magnets (SMMs) present a promising avenue to develop spintronic technologies. Addressing individual molecules with electrical leads in SMM-based spintronic devices remains a ubiquitous challenge: interactions with metallic electrodes can drastically modify the SMM's properties by charge transfer or through changes in the molecular structure. Here, we probe electrical transport through individual Fe4 SMMs using a scanning tunnelling microscope at 0.5 K. Correlation of topographic and spectroscopic information permits identification of the spin excitation fingerprint of intact Fe4 molecules. Building from this, we find that the exchange coupling strength within the molecule's magnetic core is significantly enhanced. First-principles calculations support the conclusion that this is the result of confinement of the molecule in the two-contact junction formed by the microscope tip and the sample surface.

  9. Calibration of tip and sample temperature of a scanning tunneling microscope using a superconductive sample

    International Nuclear Information System (INIS)

    Stocker, Matthias; Pfeifer, Holger; Koslowski, Berndt

    2014-01-01

    The temperature of the electrodes is a crucial parameter in virtually all tunneling experiments. The temperature not only controls the thermodynamic state of the electrodes but also causes thermal broadening, which limits the energy resolution. Unfortunately, the construction of many scanning tunneling microscopes inherits a weak thermal link between tip and sample in order to make one side movable. Such, the temperature of that electrode is badly defined. Here, the authors present a procedure to calibrate the tip temperature by very simple means. The authors use a superconducting sample (Nb) and a standard tip made from W. Due to the asymmetry in the density of states of the superconductor (SC)—normal metal (NM) tunneling junction, the SC temperature controls predominantly the density of states while the NM controls the thermal smearing. By numerically simulating the I-V curves and numerically optimizing the tip temperature and the SC gap width, the tip temperature can be accurately deduced if the sample temperature is known or measureable. In our case, the temperature dependence of the SC gap may serve as a temperature sensor, leading to an accurate NM temperature even if the SC temperature is unknown

  10. A scanning tunneling microscope capable of imaging specified micron-scale small samples

    Science.gov (United States)

    Tao, Wei; Cao, Yufei; Wang, Huafeng; Wang, Kaiyou; Lu, Qingyou

    2012-12-01

    We present a home-built scanning tunneling microscope (STM) which allows us to precisely position the tip on any specified small sample or sample feature of micron scale. The core structure is a stand-alone soft junction mechanical loop (SJML), in which a small piezoelectric tube scanner is mounted on a sliding piece and a "U"-like soft spring strip has its one end fixed to the sliding piece and its opposite end holding the tip pointing to the sample on the scanner. Here, the tip can be precisely aligned to a specified small sample of micron scale by adjusting the position of the spring-clamped sample on the scanner in the field of view of an optical microscope. The aligned SJML can be transferred to a piezoelectric inertial motor for coarse approach, during which the U-spring is pushed towards the sample, causing the tip to approach the pre-aligned small sample. We have successfully approached a hand cut tip that was made from 0.1 mm thin Pt/Ir wire to an isolated individual 32.5 × 32.5 μm2 graphite flake. Good atomic resolution images and high quality tunneling current spectra for that specified tiny flake are obtained in ambient conditions with high repeatability within one month showing high and long term stability of the new STM structure. In addition, frequency spectra of the tunneling current signals do not show outstanding tip mount related resonant frequency (low frequency), which further confirms the stability of the STM structure.

  11. High vacuum tip-enhanced Raman spectroscope based on a scanning tunneling microscope.

    Science.gov (United States)

    Fang, Yurui; Zhang, Zhenglong; Sun, Mengtao

    2016-03-01

    In this paper, we present the construction of a high-vacuum tip-enhanced Raman spectroscopy (HV-TERS) system that allows in situ sample preparation and measurement. A detailed description of the prototype instrument is presented with experimental validation of its use and novel ex situ experimental results using the HV-TERS system. The HV-TERS system includes three chambers held under a 10(-7) Pa vacuum. The three chambers are an analysis chamber, a sample preparation chamber, and a fast loading chamber. The analysis chamber is the core chamber and contains a scanning tunneling microscope (STM) and a Raman detector coupled with a 50 × 0.5 numerical aperture objective. The sample preparation chamber is used to produce single-crystalline metal and sub-monolayer molecular films by molecular beam epitaxy. The fast loading chamber allows ex situ preparation of samples for HV-TERS analysis. Atomic resolution can be achieved by the STM on highly ordered pyrolytic graphite. We demonstrate the measurement of localized temperature using the Stokes and anti-Stokes TERS signals from a monolayer of 1,2-benzenedithiol on a gold film using a gold tip. Additionally, plasmonic catalysis can be monitored label-free at the nanoscale using our device. Moreover, the HV-TERS experiments show simultaneously activated infrared and Raman vibrational modes, Fermi resonance, and some other non-linear effects that are not observed in atmospheric TERS experiments. The high spatial and spectral resolution and pure environment of high vacuum are beneficial for basic surface studies.

  12. A novel high temperature scanning tunneling microscope for investigating semiconductor surfaces

    Science.gov (United States)

    Lamb, Mark Alan

    2001-11-01

    The issues concerning the description of structural and dynamic features at the nanometer scale has become an active field of research in surface science. The development of the scanning tunneling microscope (STM) has begun only recently to contribute substantially in this effort. For this dissertation project, the author has designed, constructed, and utilized a high temperature ultra high vacuum STM (HT-UHV-STM) for investigating semiconducting surfaces from room temperature to 790°C. In order to isolate the instrument from external noise, the author has developed and demonstrated a novel method of approaching decoupled passive magnetic levitation for vibration isolation. Using advanced magnet technology currently available, this isolation method could achieve resonance frequencies as low as 10-3 Hz for levitation pressures as high as several MPa in a single stage. The instrument has been used to study the clean Si(111) surface at high temperatures. The electromigration phenomenon has been utilized to modify the surface steps and produce metastable reconstruction zones of the "1 x 1" phase and 5 x 5 islands. The growth of the thermodynamically favored 7 x 7 reconstruction has been observed at high temperatures within these metastable phases. The production of nanostructures on the surface by the tip of the STM has been achieved and their thermal relaxation observed and analyzed. Several new observations include the appearance of periodic oscillations in the number of Si atoms constituting each of a pair of 5 x 5 magic islands, imaging of local melting and apparent sputtering of the surface by the tip, and the spontaneous formation of clusters by heat treatment.

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

    Science.gov (United States)

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

    2016-08-01

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

  14. In situ scanning tunneling microscope tip treatment device for spin polarization imaging

    Science.gov (United States)

    Li, An-Ping [Oak Ridge, TN; Jianxing, Ma [Oak Ridge, TN; Shen, Jian [Knoxville, TN

    2008-04-22

    A tip treatment device for use in an ultrahigh vacuum in situ scanning tunneling microscope (STM). The device provides spin polarization functionality to new or existing variable temperature STM systems. The tip treatment device readily converts a conventional STM to a spin-polarized tip, and thereby converts a standard STM system into a spin-polarized STM system. The tip treatment device also has functions of tip cleaning and tip flashing a STM tip to high temperature (>2000.degree. C.) in an extremely localized fashion. Tip coating functions can also be carried out, providing the tip sharp end with monolayers of coating materials including magnetic films. The device is also fully compatible with ultrahigh vacuum sample transfer setups.

  15. The mechanism of light emission from a scanning tunnelling microscope operating in air.

    Science.gov (United States)

    Rogez, B; Cao, S; Dujardin, G; Comtet, G; Moal, E Le; Mayne, A; Boer-Duchemin, E

    2016-11-18

    The scanning tunnelling microscope (STM) may be used as a low-energy, electrical nanosource of surface plasmon polaritons and light. In this article, we demonstrate that the optimum mode of operation of the STM for maximum photon emission is completely different in air than in vacuum. To this end, we investigate the emission of photons, the variation in the relative tip-sample distance and the measured current as a function of time for an STM operating in air. Contrary to the case of an STM operating in vacuum, the measured current between the tip and sample for an STM in air is very unstable (rapidly fluctuating in time) when the applied voltage between the tip and sample is in the ∼1.5-3 V range (i.e., in the energy range of visible photons). The photon emission occurs in short (50 μs) bursts when the STM tip is closest to the sample. The current instabilities are shown to be a key ingredient for producing intense light emission from an STM operating in air (photon emission rate several orders of magnitude higher than for stable current). These results are explained in terms of the interplay between the tunnel current and the electrochemical current in the ubiquitous thin water layer that exists when working in air.

  16. Low conductive support for thermal insulation of a sample holder of a variable temperature scanning tunneling microscope

    Czech Academy of Sciences Publication Activity Database

    Hanzelka, Pavel; Vonka, J.; Musilová, Věra

    2013-01-01

    Roč. 84, č. 8 (2013), 085103:1-6 ISSN 0034-6748 R&D Projects: GA MŠk ED0017/01/01; GA TA ČR TE01020233 Institutional support: RVO:68081731 Keywords : Thermal conductiviy * Scanning tunneling microscope Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 1.584, year: 2013

  17. Systematic analyses of vibration noise of a vibration isolation system for high-resolution scanning tunneling microscopes.

    Science.gov (United States)

    Iwaya, Katsuya; Shimizu, Ryota; Hashizume, Tomihiro; Hitosugi, Taro

    2011-08-01

    We designed and constructed an effective vibration isolation system for stable scanning tunneling microscopy measurements using a separate foundation and two vibration isolation stages (i.e., a combination of passive and active vibration isolation dampers). Systematic analyses of vibration data along the horizontal and vertical directions are present, including the vibration transfer functions of each stage and the overall vibration isolation system. To demonstrate the performance of the system, tunneling current noise measurements are conducted with and without the vibration isolation. Combining passive and active vibration isolation dampers successfully removes most of the vibration noise in the tunneling current up to 100 Hz. These comprehensive vibration noise data, along with details of the entire system, can be used to establish a clear guideline for building an effective vibration isolation system for various scanning probe microscopes and electron microscopes.

  18. Scanning tunneling microscope combined with synchrotron-radiation for elemental analysis

    International Nuclear Information System (INIS)

    Okuda, T.; Eguchi, T.; Matsushima, T.; Hamada, M.; Ma, X.-D.; Kataoka, A.; Harasawa, A.; Kinoshita, T.; Hasegawa, Y.

    2004-01-01

    Full text: We present a newly developed synchrotron-radiation-illuminated scanning-tunneling-microscope (SR-STM) at BL-19A in Photon Factory (KEK, Japan). Combining the energy tunability of SR light with the high-spatial resolution of STM, we aim to develop an element-specific microscope. That is, by detecting the photoelectrons from the specific core-levels excited by SR light with STM tip, we expect an elemental mapping of the surface with high spatial resolution. Figure shows an STM image of the Si(111) 7 x 7 surface by the SR- STM in a constant current mode (V sample = - 1.2 V, I t =240 pA) with and without SR light illuminating with the photon energy ranging from hv = 93 to 105 eV. As shown in the figure, atomically resolved imaging is attained even under the light illumination. The cross-sectional profile of the STM image is shown in the right of the figure. Light shade indicates the SR illumination during scanning over the area. When the surface is illuminated by the SR light, the tip height is obviously raised. Moreover, a sharp increase of the tip height is observed above the Si L adsorption edge ( ∼ 101 eV). These results demonstrate the possibility of elemental identification using this technique. The spatial resolution of the elemental mapping is approximately micron order at present. In order to improve it, we are now testing a tip-coating and some other trial techniques

  19. Controlling molecular condensation/diffusion of copper phthalocyanine by local electric field induced with scanning tunneling microscope tip

    Science.gov (United States)

    Nagaoka, Katsumi; Yaginuma, Shin; Nakayama, Tomonobu

    2018-02-01

    We have discovered the condensation/diffusion phenomena of copper phthalocyanine (CuPc) molecules controlled with a pulsed electric field induced by the scanning tunneling microscope tip. This behavior is not explained by the conventional induced dipole model. In order to understand the mechanism, we have measured the electronic structure of the molecule by tunneling spectroscopy and also performed theoretical calculations on molecular orbitals. These data clearly indicate that the molecule is positively charged owing to charge transfer to the substrate, and that hydrogen bonding exists between CuPc molecules, which makes the molecular island stable.

  20. A High Rigidity and Precision Scanning Tunneling Microscope with Decoupled XY and Z Scans

    Directory of Open Access Journals (Sweden)

    Xu Chen

    2017-01-01

    Full Text Available A new scan-head structure for the scanning tunneling microscope (STM is proposed, featuring high scan precision and rigidity. The core structure consists of a piezoelectric tube scanner of quadrant type (for XY scans coaxially housed in a piezoelectric tube with single inner and outer electrodes (for Z scan. They are fixed at one end (called common end. A hollow tantalum shaft is coaxially housed in the XY-scan tube and they are mutually fixed at both ends. When the XY scanner scans, its free end will bring the shaft to scan and the tip which is coaxially inserted in the shaft at the common end will scan a smaller area if the tip protrudes short enough from the common end. The decoupled XY and Z scans are desired for less image distortion and the mechanically reduced scan range has the superiority of reducing the impact of the background electronic noise on the scanner and enhancing the tip positioning precision. High quality atomic resolution images are also shown.

  1. A 30 mK, 13.5 T scanning tunneling microscope with two independent tips

    Science.gov (United States)

    Roychowdhury, Anita; Gubrud, M. A.; Dana, R.; Anderson, J. R.; Lobb, C. J.; Wellstood, F. C.; Dreyer, M.

    2014-04-01

    We describe the design, construction, and performance of an ultra-low temperature, high-field scanning tunneling microscope (STM) with two independent tips. The STM is mounted on a dilution refrigerator and operates at a base temperature of 30 mK with magnetic fields of up to 13.5 T. We focus on the design of the two-tip STM head, as well as the sample transfer mechanism, which allows in situ transfer from an ultra high vacuum preparation chamber while the STM is at 1.5 K. Other design details such as the vibration isolation and rf-filtered wiring are also described. Their effectiveness is demonstrated via spectral current noise characteristics and the root mean square roughness of atomic resolution images. The high-field capability is shown by the magnetic field dependence of the superconducting gap of CuxBi2Se3. Finally, we present images and spectroscopy taken with superconducting Nb tips with the refrigerator at 35 mK that indicate that the effective temperature of our tips/sample is approximately 184 mK, corresponding to an energy resolution of 16 μeV.

  2. [Scanning electron microscopic investigations of cutting edge quality in lamellar keratotomy using the Wavelight femtosecond laser (FS-200) : What influence do spot distance and an additional tunnel have?

    Science.gov (United States)

    Hammer, T; Höche, T; Heichel, J

    2018-01-01

    Femtosecond lasers (fs-lasers) are established cutting instruments for the creation of LASIK flaps. Previous studies often showed even rougher surfaces after application of fs-laser systems compared to lamellar keratotomy with mechanical microkeratomes. When cutting the cornea with fs-lasers, an intrastromal gas development occurs, which has a potentially negative influence on the cutting quality if the gas cannot be dissipated; therefore, manufacturers have chosen the way of gas assimilation in so-called pockets. The investigated system creates a tunnel which opens under the conjunctiva. The aim of this study was to investigate the effects of a tunnel as well as the influence of different spot distances on the quality of cut surfaces and edges. In this experimental study on freshly enucleated porcine eyes (n = 15), the following cuts were carried out with the FS-200 (Wavelight, Erlangen, Germany): 1. standard setting (spot and line separation 8 µm), 2. with tunnel for gas drainage, 3. without gas-conducting tunnel, 4. with increased spot spacing (spot and line separation 9 μm instead of 8 μm) and 5. with reduced spot spacing (spot and line separation 7 μm instead of 8 μm). Subsequently, scanning electron microscopy (FEI Quanta 650, Hillsboro, OR) of the cut edges and surfaces as well as the gas drain tunnel were performed. The evaluation was based on an established score. The current fs-laser system (200 Hz) is able to create smooth cutting surfaces and sharp edges. The changed density of laser pulses compared to the standard settings with a reduced or increased distance between the pulses, did not achieve any further improvement in the surface quality. The gas-conducting tunnel could be detected by scanning electron microscope. In the case of cutting without a tunnel, roughened surfaces and irregularities on the cutting edges were found. When the FS-200 fs-laser is used, LASIK cuts with very smooth cut surfaces and sharp cutting

  3. Design and performance of an ultra-high vacuum scanning tunneling microscope operating at dilution refrigerator temperatures and high magnetic fields.

    Science.gov (United States)

    Misra, S; Zhou, B B; Drozdov, I K; Seo, J; Urban, L; Gyenis, A; Kingsley, S C J; Jones, H; Yazdani, A

    2013-10-01

    We describe the construction and performance of a scanning tunneling microscope capable of taking maps of the tunneling density of states with sub-atomic spatial resolution at dilution refrigerator temperatures and high (14 T) magnetic fields. The fully ultra-high vacuum system features visual access to a two-sample microscope stage at the end of a bottom-loading dilution refrigerator, which facilitates the transfer of in situ prepared tips and samples. The two-sample stage enables location of the best area of the sample under study and extends the experiment lifetime. The successful thermal anchoring of the microscope, described in detail, is confirmed through a base temperature reading of 20 mK, along with a measured electron temperature of 250 mK. Atomically resolved images, along with complementary vibration measurements, are presented to confirm the effectiveness of the vibration isolation scheme in this instrument. Finally, we demonstrate that the microscope is capable of the same level of performance as typical machines with more modest refrigeration by measuring spectroscopic maps at base temperature both at zero field and in an applied magnetic field.

  4. Design and performance of an ultra-high vacuum scanning tunneling microscope operating at dilution refrigerator temperatures and high magnetic fields

    Science.gov (United States)

    Misra, S.; Zhou, B. B.; Drozdov, I. K.; Seo, J.; Urban, L.; Gyenis, A.; Kingsley, S. C. J.; Jones, H.; Yazdani, A.

    2013-10-01

    We describe the construction and performance of a scanning tunneling microscope capable of taking maps of the tunneling density of states with sub-atomic spatial resolution at dilution refrigerator temperatures and high (14 T) magnetic fields. The fully ultra-high vacuum system features visual access to a two-sample microscope stage at the end of a bottom-loading dilution refrigerator, which facilitates the transfer of in situ prepared tips and samples. The two-sample stage enables location of the best area of the sample under study and extends the experiment lifetime. The successful thermal anchoring of the microscope, described in detail, is confirmed through a base temperature reading of 20 mK, along with a measured electron temperature of 250 mK. Atomically resolved images, along with complementary vibration measurements, are presented to confirm the effectiveness of the vibration isolation scheme in this instrument. Finally, we demonstrate that the microscope is capable of the same level of performance as typical machines with more modest refrigeration by measuring spectroscopic maps at base temperature both at zero field and in an applied magnetic field.

  5. Two-photon-induced hot-electron transfer to a single molecule in a scanning tunneling microscope

    International Nuclear Information System (INIS)

    Wu, S. W.; Ho, W.

    2010-01-01

    The junction of a scanning tunneling microscope (STM) operating in the tunneling regime was irradiated with femtosecond laser pulses. A photoexcited hot electron in the STM tip resonantly tunnels into an excited state of a single molecule on the surface, converting it from the neutral to the anion. The electron-transfer rate depends quadratically on the incident laser power, suggesting a two-photon excitation process. This nonlinear optical process is further confirmed by the polarization measurement. Spatial dependence of the electron-transfer rate exhibits atomic-scale variations. A two-pulse correlation experiment reveals the ultrafast dynamic nature of photoinduced charging process in the STM junction. Results from these experiments are important for understanding photoinduced interfacial charge transfer in many nanoscale inorganic-organic structures.

  6. Demonstrating the utility of boron based precursor molecules for selective area deposition in a scanning tunneling microscope

    International Nuclear Information System (INIS)

    Perkins, F.K.; Onellion, M.; Lee, S.; Bowben, T.A.

    1992-01-01

    The scanning tunneling microscope (STM) can be used to selectively deposit material from a gaseous precursor compound. Ultrasmall (less than a 100 nm across) spatial dimensions for selective area deposition may be achieved by this means. In this paper the authors outline a scheme foreselecting and designing main group cluster compounds and organometallics for this type of selective area deposition using nido-decaborane(14) as an example

  7. Variability in ACL tunnel placement: observational clinical study of surgeon ACL tunnel variability.

    Science.gov (United States)

    Wolf, Brian R; Ramme, Austin J; Wright, Rick W; Brophy, Robert H; McCarty, Eric C; Vidal, Armando R; Parker, Richard D; Andrish, Jack T; Amendola, Annunziato

    2013-06-01

    Multicenter and multisurgeon cohort studies on anterior cruciate ligament (ACL) reconstruction are becoming more common. Minimal information exists on intersurgeon and intrasurgeon variability in ACL tunnel placement. Purpose/ The purpose of this study was to analyze intersurgeon and intrasurgeon variability in ACL tunnel placement in a series of The Multicenter Orthopaedic Outcomes Network (MOON) ACL reconstruction patients and in a clinical cohort of ACL reconstruction patients. The hypothesis was that there would be minimal variability between surgeons in ACL tunnel placement. Cross-sectional study; Level of evidence, 3. Seventy-eight patients who underwent ACL reconstruction by 8 surgeons had postoperative imaging with computed tomography, and ACL tunnel location and angulation were analyzed using 3-dimensional surface processing and measurement. Intersurgeon and intrasurgeon variability in ACL tunnel placement was analyzed. For intersurgeon variability, the range in mean ACL femoral tunnel depth between surgeons was 22%. For femoral tunnel height, there was a 19% range. Tibial tunnel location from anterior to posterior on the plateau had a 16% range in mean results. There was only a small range of 4% for mean tibial tunnel location from the medial to lateral dimension. For intrasurgeon variability, femoral tunnel depth demonstrated the largest ranges, and tibial tunnel location from medial to lateral on the plateau demonstrated the least variability. Overall, surgeons were relatively consistent within their own cases. Using applied measurement criteria, 85% of femoral tunnels and 90% of tibial tunnels fell within applied literature-based guidelines. Ninety-one percent of the axes of the femoral tunnels fell within the boundaries of the femoral footprint. The data demonstrate that surgeons performing ACL reconstructions are relatively consistent between each other. There is, however, variability of average tunnel placement up to 22% of mean condylar depth

  8. First-principles theory of inelastic currents in a scanning tunneling microscope

    DEFF Research Database (Denmark)

    Stokbro, Kurt; Hu, Ben Yu-Kuang; Thirstrup, C.

    1998-01-01

    A first-principles theory of inelastic tunneling between a model probe tip and an atom adsorbed on a surface is presented, extending the elastic tunneling theory of Tersoff and Hamann. The inelastic current is proportional to the change in the local density of states at the center of the tip due...... to the addition of the adsorbate. We use the theory to investigate the vibrational heating of an adsorbate below a scanning tunneling microscopy tip. We calculate the desorption rate of PI from Si(100)-H(2 X 1) as a function of the sample bias and tunnel current, and find excellent a,agreement with recent...

  9. A Scanning Tunneling Microscope at the Milli-Kelvin, High Magnetic Field Frontier

    Science.gov (United States)

    Zhou, Brian B.

    The ability to access lower temperatures and higher magnetic fields has precipitated breakthroughs in our understanding of physical matter, revealing novel effects such as superconductivity, the integer and fractional quantum Hall effects, and single spin magnetism. Extending the scanning tunneling microscope (STM) to the extremity of the B-T phase space provides unique insight on these phenomena both at the atomic level and with spectroscopic power. In this thesis, I describe the design and operation of a full-featured, dilution refrigerator-based STM capable of sample preparation in ultra-high vacuum (UHV) and spectroscopic mapping with an electronic temperature of 240 mK in fields up to 14 T. I detail technical solutions to overcome the stringent requirements on vibration isolation, electronic noise, and mechanical design necessary to successfully integrate the triad of the STM, UHV, and dilution refrigeration. Measurements of the heavy fermion superconductor CeCoIn5 ( Tc = 2.3 K) directly leverage the resulting combination of ultra-low temperature and atomic resolution to identify its Cooper pairing to be of dx2-y2 symmetry. Spectroscopic and quasiparticle interference measurements isolate a Kondo-hybridized, heavy effective mass band near the Fermi level, from which nodal superconductivity emerges in CeCoIn5 in coexistence with an independent pseudogap. Secondly, the versatility of this instrument is demonstrated through measurements of the three-dimensional Dirac semimetal Cd3As2 up to the maximum magnetic field. Through high resolution Landau level spectroscopy, the dispersion of the conduction band is shown to be Dirac-like over an unexpectedly extended regime, and its two-fold degeneracy to be lifted in field through a combination of orbital and Zeeman effects. Indeed, these two experiments on CeCoIn5 and Cd3 As2 glimpse the new era of nano-scale materials research, spanning superconductivity, topological properties, and single spin phenomena, made

  10. A study for the KAERI research tunnel

    International Nuclear Information System (INIS)

    Kim, J.; Hwang, Y. S.; Park, H. S.; Park, S. K.; Park, B. Y.; Bang, K. S.; Kuh, J. H.; Kang, K. H.

    1997-12-01

    Major goal of the R and D on the KAERI Research Tunnel in 1997 are 1) concept development of the KAERI research tunnel and its major units 2) computer simulation of facilities 3) study on thermo-hydro mechanical coupling in the vicinity of a waste repository 4) effect of excavated distrubed zone. In addition supplementary site investigation to understand the distribution of stresses in the site was done along with long term monitoring of the water table. (author). 44 refs., 16 tabs., 36 figs

  11. Analysis of photon-scanning tunneling microscope images of inhomogeneous samples: Determination of the local refractive index of channel waveguides

    International Nuclear Information System (INIS)

    Bourillot, E.; Fornel, F. de.; Goudonnet, J.P.

    1995-01-01

    Channel waveguides are imaged by a photon-scanning tunneling microscope (PSTM). The polarization of the light and its orientation with respect to the guide aids are shown to be very important parameters in the analysis of the images of such samples. We simulated image formation for the plane of incidence parallel to the axis of the guide. Our theoretical results are qualitatively in agreement with our measurements. These results show the ability of the PSTM to give information about the local refractive-index variations of a sample. 21 refs., 14 figs

  12. Tunneling Spectroscopy Study of Spin-Polarized Quasiparticle Injection Effects in Cuparate/Manganite Heterostructures

    Science.gov (United States)

    Wei, J. Y. T.; Yeh, N. C.; Vasquez, R. P.

    1998-01-01

    Scanning tunneling spectroscopy was performed at 4.2K on epitaxial thin-film heterostructures comprising YBa2Cu3O7 and La0.7Ca0.3MnO3, to study the microscopic effects of spin-polarized quasiparticle injection from the half-metallic ferromagnetic manganite on the high-Tc cuprate superconductor.

  13. Scanning tunneling microscopy studies of diamond films and optoelectronic materials

    Science.gov (United States)

    Perez, Jose M.

    1993-01-01

    In this report, we report on progress achieved from 12/1/92 to 10/1/93 under the grant entitled 'Scanning Tunneling Microscopy Studies of Diamond Films and Optoelectronic Materials'. We have set-up a chemical vapor deposition (CVD) diamond film growth system and a Raman spectroscopy system to study the nucleation and growth of diamond films with atomic resolution using scanning tunneling microscopy (STM). A unique feature of the diamond film growth system is that diamond films can be transferred directly to the ultrahigh vacuum (UHV) chamber of a scanning tunneling microscope without contaminating the films by exposure to air. The University of North Texas (UNT) provided $20,000 this year as matching funds for the NASA grant to purchase the diamond growth system. In addition, UNT provided a Coherent Innova 90S Argon ion laser, a Spex 1404 double spectrometer, and a Newport optical table costing $90,000 to set-up the Raman spectroscopy system. The CVD diamond growth system and Raman spectroscopy system will be used to grow and characterize diamond films with atomic resolution using STM as described in our proposal. One full-time graduate student and one full-time undergraduate student are supported under this grant. In addition, several graduate and undergraduate students were supported during the summer to assist in setting-up the diamond growth and Raman spectroscopy systems. We have obtained research results concerning STM of the structural and electronic properties of CVD grown diamond films, and STM and scanning tunneling spectroscopy of carbon nanotubes. In collaboration with the transmission electron microscopy (TEM) group at UNT, we have also obtained results concerning the optoelectronic material siloxene. These results were published in refereed scientific journals, submitted for publication, and presented as invited and contributed talks at scientific conferences.

  14. Development of Near-Field Microwave Microscope with the Functionality of Scanning Tunneling Spectroscopy

    Science.gov (United States)

    Machida, Tadashi; Gaifullin, Marat B.; Ooi, Shuuich; Kato, Takuya; Sakata, Hideaki; Hirata, Kazuto

    2010-11-01

    We describe the details of an original near-field scanning microwave microscope, developed for simultaneous measurements of local density-of-states (LDOS) and local ohmic losses (LOL). Improving microwave detection systems, we have succeeded in distinguishing the LDOS and LOL even between two low resistance materials; gold and highly orientated pyrolitic graphite. The experimental data indicate that our microscope holds a capability to investigate both LDOS and LOL in nanoscale.

  15. Tip preparation for usage in an ultra-low temperature UHV scanning tunneling microscope

    Directory of Open Access Journals (Sweden)

    S. Ernst, S. Wirth, M. Rams, V. Dolocan and F. Steglich

    2007-01-01

    Full Text Available This work deals with the preparation and characterization of tungsten tips for the use in UHV low-temperature scanning tunneling microscopy and spectroscopy (STM and STS, respectively. These specific environments require in situ facilities for tip conditioning, for further sharpening of the tips, as well as for reliable tip characterization. The implemented conditioning methods include direct resistive annealing, annealing by electron bombardment, and self-sputtering with noble gas ions. Moreover, results from in situ tip characterization by field emission and STM experiments were compared to ex situ scanning electron microscopy. Using the so-prepared tips, high resolution STM images and tunneling spectra were obtained in a temperature range from ambient down to 350 mK, partially with applied magnetic field, on a variety of materials.

  16. A tilting wind tunnel for fire behavior studies

    Science.gov (United States)

    David R. Weise

    1994-01-01

    The combined effects of wind velocity and slope on wildland fire behavior can be studied in the laboratory using a tilting wind tunnel. The tilting wind tunnel requires a commercially available fan to induce wind and can be positioned to simulate heading and backing fires spreading up and down slope. The tunnel is portable and can be disassembled for transport using a...

  17. Theoretical analysis of a dual-probe scanning tunneling microscope setup on graphene

    DEFF Research Database (Denmark)

    Settnes, Mikkel; Power, Stephen R.; Petersen, Dirch Hjorth

    2014-01-01

    Experimental advances allow for the inclusion of multiple probes to measure the transport properties of a sample surface. We develop a theory of dual-probe scanning tunneling microscopy using a Green's function formalism, and apply it to graphene. Sampling the local conduction properties at finite...... to different scattering processes. We compute the conductance maps of graphene systems with different edge geometries or height fluctuations to determine the effects of nonideal graphene samples on dual-probe measurements. © 2014 American Physical Society....

  18. Plasmon modes in light emission from silver nanoparticles induced by a scanning tunneling microscope

    Czech Academy of Sciences Publication Activity Database

    Kůsová, Kateřina; Charra, F.; Schull, G.; Pelant, Ivan

    2008-01-01

    Roč. 602, č. 1 (2008), s. 345-348 ISSN 0039-6028 R&D Projects: GA AV ČR IAA1010316; GA MŠk LC510; GA AV ČR IAA1010413 Institutional research plan: CEZ:AV0Z10100521 Keywords : scanning tunneling microscopy * photon emission * plasmons * silver nanoparticles Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.731, year: 2008

  19. Microscopic superconducting parameters from tunneling in A15 Nb-Sn

    International Nuclear Information System (INIS)

    Rudman, D.A.; Beasley, M.R.

    1984-01-01

    High-quality tunnel junctions have been fabricated on thin films of A15 Nb-Sn (20--25 at. %) using oxidized a-Si tunnel barriers and Pb counterelectrodes. These junctions have been used to measure changes in the gap, the transition temperature T/sub c/, and the tunneling density of states with composition in this important high-T/sub c/ superconductor. With the use of the proximity-effect-modified data reduction scheme developed by Arnold and Wolf, values for α 2 F(ω) and μ( are obtained. As the Sn content approaches stoichiometry, the lowest-energy phonon branch in α 2 F(ω) both increases in weight and shifts to lower energy. These two effects combine to produce the increases in lambda as stoichiometry is approached, and at the same time can account for the observed increase in 2Δ/k/sub B/T/sub c/. The values of μ( remain essentially constant as a function of composition, and hence show no evidence for an increased Coulomb interaction with increasing disorder as recently proposed by Anderson et al

  20. TC study of the carpal tunnel

    International Nuclear Information System (INIS)

    Martelli, A.; Gozzoli, L.; Uggetti, C.; Zanlungo, M.; Ferrari, P.; Leddi, G.

    1987-01-01

    The standard technique for CT investigation of the carpal tunnel and its normal anatomy were studied. Ten healty asymptomatic volunteers, age 25-45, underwent wrist CT. The hand is placed in prone position with the third metacarpus in line with radius. Digital radiograph and four axial CT scans are performed respectively: at the distal end of the radius, at the scaphoid tubercle level, at the hamate hook level and at the carpal and metacarpal joint. Standard carpal tunnel diameters are thus available with good reliability and repeatibility when correct technique is adopted. The results permit a morphological description of the osseous walls, transverse ligament, flexor tendons with synovial sheets and median nerve. Gujon's canal and its content can also be investigated

  1. A novel cryogenic scanning laser microscope tested on Josephson tunnel junctions

    DEFF Research Database (Denmark)

    Holm, Jesper; Mygind, Jesper

    1995-01-01

    A novel cryogenic scanning laser microscope with a spatial resolution of less than 5 µm has been designed for on-chip in situ investigations of the working properties of normal and superconducting circuits and devices. The instrument relies on the detection of the electrical response of the circuit...... to a very localized heating induced by irradiation with 675 nm wavelength light from a semiconductor laser. The hot spot is moved by a specially designed piezoelectric scanner sweeping the tip of a single-mode optical fiber a few µm above the circuit. Depending on the scanner design the scanning area can...... be as large as 50×500 µm2 at 4.2 K. The microscope can be operated in the temperature range 2–300 K using a standard temperature controller. The central microscope body is mounted inside the vacuum can of a dip-stick-type cryoprobe. A damped spring system is used to reduce interference from extraneous...

  2. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability

    Science.gov (United States)

    Wang, Qi; Hou, Yubin; Wang, Junting; Lu, Qingyou

    2013-11-01

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d31 coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices.

  3. A high-stability scanning tunneling microscope achieved by an isolated tiny scanner with low voltage imaging capability

    International Nuclear Information System (INIS)

    Wang, Qi; Wang, Junting; Lu, Qingyou; Hou, Yubin

    2013-01-01

    We present a novel homebuilt scanning tunneling microscope (STM) with high quality atomic resolution. It is equipped with a small but powerful GeckoDrive piezoelectric motor which drives a miniature and detachable scanning part to implement coarse approach. The scanning part is a tiny piezoelectric tube scanner (industry type: PZT-8, whose d 31 coefficient is one of the lowest) housed in a slightly bigger polished sapphire tube, which is riding on and spring clamped against the knife edges of a tungsten slot. The STM so constructed shows low back-lashing and drifting and high repeatability and immunity to external vibrations. These are confirmed by its low imaging voltages, low distortions in the spiral scanned images, and high atomic resolution quality even when the STM is placed on the ground of the fifth floor without any external or internal vibration isolation devices

  4. Development of a Millikelvin dual-tip Josephson scanning tunneling microscope

    Science.gov (United States)

    Roychowdhury, Anita

    In this thesis, I first describe the design and construction of a dual-tip millikelvin STM system. The STM is mounted on a dilution refrigerator and the setup includes vibration isolation, rf-filtered wiring, an ultra high vacuum (UHV) sample preparation chamber and sample transfer mechanism. Next I describe a novel superconducting tip fabrication technique. My technique involves dry-etching sections of 250 mum diameter Nb wire with an SF6 plasma in a reactive ion etcher. I present data taken with these tips on various samples at temperatures ranging from 30 mK to 9 K. My results demonstrate that the tips are superconducting, achieve good spectroscopic energy resolution, are mechanically robust over long time periods, and are atomically sharp. I also show data characterizing the performance of our system. This data is in the form of atomic resolution images, spectroscopy, noise spectra and simultaneous scans taken with both tips of the STM. I used these to examine the tip-sample stability, cross talk between the two tips, and to extract the effective noise temperature (˜185 mK) of the sample by fitting the spectroscopy data to a voltage noise model. Finally, I present spectroscopy data taken with a Nb tip on a Nb(100) sample at 30 mK. The enhanced spectroscopic resolution at this temperature allowed me to resolve peaks in the fluctuation-dominated supercurrent at sub-gap voltages. My analysis indicates that these peaks are due to the incoherent tunneling of Cooper pairs at resonant frequencies of the STM's electromagnetic environment. By measuring the response of the STM junction to microwaves, I identified the charge carriers in this regime as Cooper pairs with charge 2e. The amplitude of the response current scales as the square of the Bessel functions, indicating that the pair tunneling originates from photon assisted tunneling in the incoherent regime, rather than the more conventionally observed Shapiro steps in the coherent regime.

  5. A 10 mK scanning tunneling microscope operating in ultra high vacuum and high magnetic fields.

    Science.gov (United States)

    Assig, Maximilian; Etzkorn, Markus; Enders, Axel; Stiepany, Wolfgang; Ast, Christian R; Kern, Klaus

    2013-03-01

    We present design and performance of a scanning tunneling microscope (STM) that operates at temperatures down to 10 mK providing ultimate energy resolution on the atomic scale. The STM is attached to a dilution refrigerator with direct access to an ultra high vacuum chamber allowing in situ sample preparation. High magnetic fields of up to 14 T perpendicular and up to 0.5 T parallel to the sample surface can be applied. Temperature sensors mounted directly at the tip and sample position verified the base temperature within a small error margin. Using a superconducting Al tip and a metallic Cu(111) sample, we determined an effective temperature of 38 ± 1 mK from the thermal broadening observed in the tunneling spectra. This results in an upper limit for the energy resolution of ΔE = 3.5 kBT = 11.4 ± 0.3 μeV. The stability between tip and sample is 4 pm at a temperature of 15 mK as demonstrated by topography measurements on a Cu(111) surface.

  6. A 10Â mK scanning tunneling microscope operating in ultra high vacuum and high magnetic fields

    Science.gov (United States)

    Assig, Maximilian; Etzkorn, Markus; Enders, Axel; Stiepany, Wolfgang; Ast, Christian R.; Kern, Klaus

    2013-03-01

    We present design and performance of a scanning tunneling microscope (STM) that operates at temperatures down to 10 mK providing ultimate energy resolution on the atomic scale. The STM is attached to a dilution refrigerator with direct access to an ultra high vacuum chamber allowing in situ sample preparation. High magnetic fields of up to 14 T perpendicular and up to 0.5 T parallel to the sample surface can be applied. Temperature sensors mounted directly at the tip and sample position verified the base temperature within a small error margin. Using a superconducting Al tip and a metallic Cu(111) sample, we determined an effective temperature of 38 ± 1 mK from the thermal broadening observed in the tunneling spectra. This results in an upper limit for the energy resolution of ΔE = 3.5kBT = 11.4 ± 0.3 μeV. The stability between tip and sample is 4 pm at a temperature of 15 mK as demonstrated by topography measurements on a Cu(111) surface.

  7. Metallocene Molecular Clusters Studied with Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Kwon, Jeonghoon; Ham, Ungdon; Lee, Minjun; Lim, Seong Joon; Kuk, Young

    2014-03-01

    Atomic spins and molecular magnets have been actively reported using Scanning Tunneling Microscope(STM) in recent studies. One can even assemble an artificial magnet by STM manipulation. Manganocene((C5H5)2 Mn), a sandwich complex of metallocene, is composed of one manganese atom and two cyclopentadianyl ligands. This molecule is known to reveal not only high spin number S = 5/2 at room temperature but also two structural states: monomer and molecular chain. In this presentation, we report STM images and spectroscopic results of these monomers and dimers. We try to map the molecular electronic state and the spin texture. The molecule is adsorbed on an insulating layer to decouple the spin state from the metallic substrate. We will present that manganocene can become a basic element of a spin chain.

  8. Scanning Tunneling Microscopic Observation of Adatom-Mediated Motifs on Gold-Thiol Self-assembled Monolayers at High Coverage

    DEFF Research Database (Denmark)

    Wang, Yun; Chi, Qijin; Hush, Noel S.

    2009-01-01

    Self-assembled monolayers (SAMs) formed by chemisorption of a branched-chain alkanethiol, 2-methyl-1-propanethiol, on Au(111) surfaces were studied by in situ scanning tunneling microscopy (STM) under electrochemical potential control and analyzed using extensive density functional theory (DFT...

  9. Proposal for Marshmallow Tunnel Stemming Study

    Energy Technology Data Exchange (ETDEWEB)

    1962-01-01

    Discussion of findings after the shot in the tunnel and instructions for a deeper drilling below the tunnel using radiation probes to help define the cavity shape and documentary photography of the findings.

  10. Combined low-temperature scanning tunneling/atomic force microscope for atomic resolution imaging and site-specific force spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Schwarz, Udo; Albers, Boris J.; Liebmann, Marcus; Schwendemann, Todd C.; Baykara, Mehmet Z.; Heyde, Markus; Salmeron, Miquel; Altman, Eric I.; Schwarz, Udo D.

    2008-02-27

    The authors present the design and first results of a low-temperature, ultrahigh vacuum scanning probe microscope enabling atomic resolution imaging in both scanning tunneling microscopy (STM) and noncontact atomic force microscopy (NC-AFM) modes. A tuning-fork-based sensor provides flexibility in selecting probe tip materials, which can be either metallic or nonmetallic. When choosing a conducting tip and sample, simultaneous STM/NC-AFM data acquisition is possible. Noticeable characteristics that distinguish this setup from similar systems providing simultaneous STM/NC-AFM capabilities are its combination of relative compactness (on-top bath cryostat needs no pit), in situ exchange of tip and sample at low temperatures, short turnaround times, modest helium consumption, and unrestricted access from dedicated flanges. The latter permits not only the optical surveillance of the tip during approach but also the direct deposition of molecules or atoms on either tip or sample while they remain cold. Atomic corrugations as low as 1 pm could successfully be resolved. In addition, lateral drifts rates of below 15 pm/h allow long-term data acquisition series and the recording of site-specific spectroscopy maps. Results obtained on Cu(111) and graphite illustrate the microscope's performance.

  11. Wrist immobilization after carpal tunnel release: a prospective study

    OpenAIRE

    Martins Roberto S.; Siqueira Mario G.; Simplício Hougelli

    2006-01-01

    This prospective study evaluates the possible advantages of wrist imobilization after open carpal tunnel release comparing the results of two weeks immobilization and no immobilization. Fifty two patients with idiopathic carpal tunnel syndrome were randomly selected in two groups after open carpal tunnel release. In one group (A, n=26) the patients wore a neutral-position wrist splint continuosly for two weeks. In the other group (B, n=26) no wrist immobilization was used. Clinical assessment...

  12. What is the orientation of the tip in a scanning tunneling microscope?

    Science.gov (United States)

    Mándi, Gábor; Teobaldi, Gilberto; Palotás, Krisztián

    2015-05-01

    The atomic structure and electronic properties of the tip apex can strongly affect the contrast of scanning tunneling microscopy (STM) images. This is a critical issue in STM imaging given the, to date unsolved, experimental limitations in precise control of the tip apex atomic structure. Definition of statistically robust procedures to indirectly obtain information on the tip apex structure is highly desirable as it would open up for more rigorous interpretation and comparison of STM images from different experiments. To this end, here we introduce a statistical correlation analysis method to obtain information on the local geometry and orientation of the tip used in STM experiments based on large scale simulations. The key quantity is the relative brightness correlation of constant-current topographs between experimental and simulated data. This correlation can be analyzed statistically for a large number of modeled tip orientations and geometries. Assuming a stable tip during the STM scans and based on the correlation distribution, it is possible to determine the tip orientations that are most likely present in an STM experiment, and exclude other orientations. This is especially important for substrates such as highly oriented pyrolytic graphite (HOPG) since its STM contrast is strongly tip dependent, which makes interpretation and comparison of STM images very challenging. We illustrate the applicability of our method considering the HOPG surface in combination with tungsten tip models of two different apex geometries and 18,144 different orientations. We calculate constant-current profiles along the direction of the HOPG(0 0 0 1) surface in the | V | ⩽ 1V bias voltage range, and compare them with experimental data. We find that a blunt tip model provides better correlation with the experiment for a wider range of tip orientations and bias voltages than a sharp tip model. Such a combination of experiments and large scale simulations opens up the way for

  13. Sediment and Cavitation Erosion Studies through Dam Tunnels

    Directory of Open Access Journals (Sweden)

    Muhammad Abid

    2016-01-01

    Full Text Available This paper presents results of sediment and cavitation erosion through Tunnel 2 and Tunnel 3 of Tarbela Dam in Pakistan. Main bend and main branch of Tunnel 2 and outlet 1 and outlet 3 of Tunnel 3 are concluded to be critical for cavitation and sediment erosion. Studies are also performed for increased sediments flow rate, concluding 5 kg/sec as the critical value for sudden increase in erosion rate density. Erosion rate is concluded to be the function of sediment flow rate and head condition. Particulate mass presently observed is reasonably low, hence presently not affecting the velocity and the flow field.

  14. Structural Safety Assessment of Existing Multiarch Tunnel: A Case Study

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2017-01-01

    Full Text Available Structural health assessment is one of the key activities in maintaining the performance of a tunnel during its service life. Due to the development of modern detection technology, comprehensive structural health assessment system is being established for operating tunnels. To evaluate the actual operational state of Shitigou tunnel, overall detection of the liner crack, tunnel seepage, and liner void was conducted by employing the modern detection technology, such as crack width monitoring technology, concrete strength monitoring technology, and electromagnetic wave nondestructive monitoring technology. Through the statistical analysis of the detection results, the distribution characteristic, development law, and damage grade of structural defects were obtained. Tunnel liner cracks are mainly located on the middle wall; serious water leakage is encountered on the side wall, middle wall, and vault; the strength of foundation and liner structure of left tunnel does not meet the design requirement; the liner voids are mostly located at the tunnel entrance section, especially, on the tunnel vault; and the proportion of influence factors of structural defects should be considered. The research results presented for this study can serve as references for effective design and health assessment of existing multiarch tunnel projects.

  15. MACROSCOPICAL AND MICROSCOPICAL STUDIES ON THE ...

    African Journals Online (AJOL)

    Caesalpinia crista leaves are bipinnate of about six pairs with alternate leaflets while the stem us fibrous, cylindrical hollow and prickly. Microscopical examination revealed the presence of strained cuticle, straight-walled epidermal cells, paracytic stomata, unicellular covering trichomes, fibres, prisms as well as cluster of ...

  16. Construction of a four tip scanning tunneling microscope/scanning electron microscope combination and conductivity measurements of silicide nanowires; Aufbau einer Vierspitzen-Rastertunnelmikroskop/Rasterelektronenmikroskop-Kombination und Leitfaehigkeitsmessungen an Silizid Nanodraehten

    Energy Technology Data Exchange (ETDEWEB)

    Zubkov, Evgeniy

    2013-09-01

    In this work the combination of a four-tip scanning tunneling microscope with a scanning electron microscope is presented. By means of this apparatus it is possible to perform the conductivity measurements on the in-situ prepared nanostructures in ultra-high vacuum. With the aid of a scanning electron microscope (SEM), it becomes possible to position the tunneling tips of the four-tip scanning tunneling microscope (STM), so that an arrangement for a four-point probe measurement on nanostructures can be obtained. The STM head was built according to the novel coaxial Beetle concept. This concept allows on the one hand, a very compact arrangement of the components of the STM and on the other hand, the new-built STM head has a good mechanical stability, in order to achieve atomic resolution with all four STM units. The atomic resolution of the STM units was confirmed by scanning a Si(111)-7 x 7 surface. The thermal drift during the STM operation, as well as the resonant frequencies of the mechanical structure of the STM head, were determined. The scanning electron microscope allows the precise and safe navigation of the tunneling tips on the sample surface. Multi tip spectroscopy with up to four STM units can be performed synchronously. To demonstrate the capabilities of the new-built apparatus the conductivity measurements were carried out on metallic yttrium silicide nanowires. The nanowires were prepared by the in-situ deposition of yttrium on a heated Si(110) sample surface. Current-voltage curves were recorded on the nanowires and on the wetting layer in-between. The curves indicate an existence of the Schottky barrier between the yttrium silicide nanowires and the silicon bulk. By means of the two-tip measurements with a gate, the insulating property of the Schottky barrier has been confirmed. Using this Schottky barrier, it is possible to limit the current to the nanowire and to prevent it from flowing through the silicon bulk. A four-tip resistance measurement

  17. Sensor integration study for a shallow tunnel detection system.

    Energy Technology Data Exchange (ETDEWEB)

    Yee, Mark L.; Abbott, Robert E.; Bonal, Nedra; Elbring, Gregory Jay; Senglaub, Michael E.

    2010-02-01

    During the past several years, there has been a growing recognition of the threats posed by the use of shallow tunnels against both international border security and the integrity of critical facilities. This has led to the development and testing of a variety of geophysical and surveillance techniques for the detection of these clandestine tunnels. The challenges of detection of these tunnels arising from the complexity of the near surface environment, the subtlety of the tunnel signatures themselves, and the frequent siting of these tunnels in urban environments with a high level of cultural noise, have time and again shown that any single technique is not robust enough to solve the tunnel detection problem in all cases. The question then arises as to how to best combine the multiple techniques currently available to create an integrated system that results in the best chance of detecting these tunnels in a variety of clutter environments and geologies. This study utilizes Taguchi analysis with simulated sensor detection performance to address this question. The analysis results show that ambient noise has the most effect on detection performance over the effects of tunnel characteristics and geological factors.

  18. A modular designed ultra-high-vacuum spin-polarized scanning tunneling microscope with controllable magnetic fields for investigating epitaxial thin films.

    Science.gov (United States)

    Wang, Kangkang; Lin, Wenzhi; Chinchore, Abhijit V; Liu, Yinghao; Smith, Arthur R

    2011-05-01

    A room-temperature ultra-high-vacuum scanning tunneling microscope for in situ scanning freshly grown epitaxial films has been developed. The core unit of the microscope, which consists of critical components including scanner and approach motors, is modular designed. This enables easy adaptation of the same microscope units to new growth systems with different sample-transfer geometries. Furthermore the core unit is designed to be fully compatible with cryogenic temperatures and high magnetic field operations. A double-stage spring suspension system with eddy current damping has been implemented to achieve ≤5 pm z stability in a noisy environment and in the presence of an interconnected growth chamber. Both tips and samples can be quickly exchanged in situ; also a tunable external magnetic field can be introduced using a transferable permanent magnet shuttle. This allows spin-polarized tunneling with magnetically coated tips. The performance of this microscope is demonstrated by atomic-resolution imaging of surface reconstructions on wide band-gap GaN surfaces and spin-resolved experiments on antiferromagnetic Mn(3)N(2)(010) surfaces.

  19. COMPARATIVE-STUDY OF 3 SEMIAUTOMATED SPECULAR MICROSCOPES

    NARCIS (Netherlands)

    LANDESZ, M; SIERTSEMA, JV; VANRIJ, G

    We compared two clinical video-assisted specular microscopes (Zeiss, noncontact, and the wide-field Keeler Konan sp 3300, contact) with an autofocus microscope (Konan noncon Robo-ca sp 8000, noncontact) with built-in analyzing software by studying the morphometry of the central corneal endothelium

  20. Contact magnetoresistance of multilayered cobalt/copper nanostructures measured by scanning tunneling microscope

    Science.gov (United States)

    Morrow, Paul-Shane

    Giant magnetoresistance (GMR) is the change in resistance of a series of ferromagnetic/nonmagnetic (F/N) layers in an applied magnetic field. Due to its potential in magnetic sensing and data storage applications, GMR has been a topic of intense research since its discovery 20 years ago. When the source current is passed perpendicular to the planes (CPP geometry) of the F/N layers, wire- or column-shaped nanostructures are preferred over conventional planar films because their reduced lateral dimension results in a larger resistance, allowing measurements at room temperature. F/N nanostructures previously implemented to exhibit CPP-GMR require extensive postdeposition modifications, specialized substrates, or use microfabrication techniques that are not vacuum-based. For the first time oblique angle deposition (OAD) is used to create a new F/N system that exhibits CPP-GMR at room temperature. OAD is a long-known physical vapor deposition technique in which nanostructure growth is achieved through a shadowing effect that occurs when the substrate is tilted to highly glancing angles relative to the incident flux. The samples grown for this study are slanted or vertical multilayered Co/Cu nanocolumns deposited by dual source thermal evaporation. For the vertical columns, the Co and Cu layer thicknesses tl were equal with t l = 4 nm and the bilayer number M = 34, while for the slanted nanocolumns tl = 4, 7, and 16 nm, with bilayer number M = 50, 42, and 21, respectively. The physical structure of these nanocolumns was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), and electron energy-loss spectroscopy (EELS). The vertical columns had larger diameter (˜100 nm) and showed more branching on their outer surface due to the substrate rotation. The slanted columns had a smaller diameter (˜50 nm), possessed a smoother exterior surface, and showed a clear multilayered Co/Cu structure from EELS imaging. X-ray diffraction (XRD) pole

  1. A microscopic study of nuclear deformed states

    International Nuclear Information System (INIS)

    Jarrio, M.M.

    1996-06-01

    Traditional models of collective nuclear rotations are phenomenological in nature, relying on a relatively small number of shape variables to characterize the deformation of the nuclear surface. Although generally successful, such models have a number of drawbacks. In particular, the fermionic many-body nature of the nucleus is ignored, and hence such models cannot adequately describe the intrinsic matter flows within the nucleus. Recently, group theoretical techniques have led to algebraic descriptions of nuclear rotation which are microscopically realizable. That is, such models can describe the collective rotation of the nucleus as a whole in terms of the coordinates and momenta of individual nucleons. This thesis describes two such models - the SU(3) model and the Sp(3,R) model - in some detail. Expressions are obtained for physical observables relevant to rotational nuclei, and comparison is made with experimental data for even-mass nuclei. A particular objective is the identification of those representations which play a dominant role in the physical state of the nucleus, and the interpretation of these states in microscopic shell-model terms. Finally, spin and intrinsic single-particle degrees of freedom are included in the SU(3) and Sp(3,R) models, and a prescription is formulated for an eventual comparison with experimental data for odd-mass nuclei

  2. A study on improving the resolution of confocal microscope

    International Nuclear Information System (INIS)

    Kim, Young June; Song, Dae Ho; Ryu, Weon Jae

    2001-01-01

    In modern industry, the accuracy and the surface-finish requirements for machined parts have been becoming ever more stringent. Optical method in measurements is used in vibration measurement, crack and defect detection with the advent of opto-mechatronics, and it is expected to play an important role in surface topography. In this study, the principle of confocal microscope is described, and the advanced 3-D surface measuring system that has better measuring speed than the traditional confocal microscope is developed. A study on improving the resolution of the advanced confocal microscope is followed. Finally, Software for data acquisition and analysis of various parameters in surface geometrical features has been developed.

  3. Joule heating and spin-transfer torque investigated on the atomic scale using a spin-polarized scanning tunneling microscope.

    Science.gov (United States)

    Krause, S; Herzog, G; Schlenhoff, A; Sonntag, A; Wiesendanger, R

    2011-10-28

    The influence of a high spin-polarized tunnel current onto the switching behavior of a superparamagnetic nanoisland on a nonmagnetic substrate is investigated by means of spin-polarized scanning tunneling microscopy. A detailed lifetime analysis allows for a quantification of the effective temperature rise of the nanoisland and the modification of the activation energy barrier for magnetization reversal, thereby using the nanoisland as a local thermometer and spin-transfer torque analyzer. Both the Joule heating and spin-transfer torque are found to scale linearly with the tunnel current. The results are compared to experiments performed on lithographically fabricated magneto-tunnel junctions, revealing a very high spin-transfer torque switching efficiency in our experiments.

  4. Scanning tunneling spectroscopy study of DNA conductivity

    Czech Academy of Sciences Publication Activity Database

    Kratochvílová, Irena; Král, Karel; Bunček, M.; Nešpůrek, Stanislav; Todorciuc, Tatiana; Weiter, M.; Navrátil, J.; Schneider, Bohdan; Pavluch, J.

    2008-01-01

    Roč. 6, č. 3 (2008), s. 422-426 ISSN 1895-1082 R&D Projects: GA AV ČR KAN401770651; GA MŠk OC 137; GA AV ČR KAN400720701; GA AV ČR KAN200100801 Institutional research plan: CEZ:AV0Z10100520; CEZ:AV0Z40500505; CEZ:AV0Z40550506 Keywords : molecular electronics * DNA * scanning tunneling microscopy * conductivity * charge carrier transport Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.448, year: 2008

  5. Geological Hazards analysis in Urban Tunneling by EPB Machine (Case study: Tehran subway line 7 tunnel

    Directory of Open Access Journals (Sweden)

    Hassan Bakhshandeh Amnieh

    2016-06-01

    Full Text Available Technological progress in tunneling has led to modern and efficient tunneling methods in vast underground spaces even under inappropriate geological conditions. Identification and access to appropriate and sufficient geological hazard data are key elements to successful construction of underground structures. Choice of the method, excavation machine, and prediction of suitable solutions to overcome undesirable conditions depend on geological studies and hazard analysis. Identifying and investigating the ground hazards in excavating urban tunnels by an EPB machine could augment the strategy for improving soil conditions during excavation operations. In this paper, challenges such as geological hazards, abrasion of the machine cutting tools, clogging around these tools and inside the chamber, diverse work front, severe water level fluctuations, existence of water, and fine-grained particles in the route were recognized in a study of Tehran subway line 7, for which solutions such as low speed boring, regular cutter head checks, application of soil improving agents, and appropriate grouting were presented and discussed. Due to the presence of fine particles in the route, foam employment was suggested as the optimum strategy where no filler is needed.

  6. Theory for Spin Selective Andreev Re ection in Vortex Core of Topological Superconductor: Majorana Zero Modes on Spherical Surface and Application to Spin Polarized Scanning Tunneling Microscope Probe

    Science.gov (United States)

    Zhang, Fu-Chun; Hu, Lun-Hui; Li, Chuang; Xu, Dong-Hui; Zhou, Yi

    Majorana zero modes (MZMs) have been predicted to exist in the topological insulator (TI)/superconductor (SC) heterostructure. Recent spin polarized scanning tunneling microscope(STM) experiment has observed spin-polarization dependence of the zero bias differential tunneling conductance at the center of vortex core. Here we consider a helical electron system described by a Rashba spin orbit coupling Hamiltonian on a spherical surface with a s-wave superconducting pairing due to proximity effect. We examine in-gap excitations of a pair of vortices with one at the north pole and the other at the south pole. While the MZM is not a spin eigenstate, the spin wavefunction of the MZM at the center of the vortex core, r = 0, is parallel to the magnetic field, and the local Andreev reflection of the MZM is spin selective, namely occurs only when the STM tip has the spin polarization parallel to the magnetic field, similar to the case in 1-dimensional nanowire. The total local differential tunneling conductance consists of the normal term proportional to the local density of states and an additional term arising from the Andreev reflection. We apply our theory to examine the recently reported spin-polarized STM experiments and show good agreement with the experiments

  7. Full scale subsonic wind tunnel requirements and design studies

    Science.gov (United States)

    Kelly, M. W.; Mort, K. W.; Hickey, D. H.

    1972-01-01

    The justification and requirements are summarized for a large subsonic wind tunnel capable of testing full-scale aircraft, rotor systems, and advanced V/STOL aircraft propulsion systems. The design considerations and constraints for such a facility are reviewed, and the trades between facility test capability and costs are discussed. The design studies showed that the structural cost of this facility is the most important cost factor. For this reason (and other considerations such as requirements for engine exhaust gas purging) an open-return wind tunnel having two test sections was selected. The major technical problem in the design of an open-return wind tunnel is maintaining good test section flow quality in the presence of external winds. This problem has been studied extensively, and inlet and exhaust systems which provide satisfactory attenuation of the effects of external winds on test section flow quality were developed.

  8. Comparative study of image contrast in scanning electron microscope and helium ion microscope.

    Science.gov (United States)

    O'Connell, R; Chen, Y; Zhang, H; Zhou, Y; Fox, D; Maguire, P; Wang, J J; Rodenburg, C

    2017-12-01

    Images of Ga + -implanted amorphous silicon layers in a 110 n-type silicon substrate have been collected by a range of detectors in a scanning electron microscope and a helium ion microscope. The effects of the implantation dose and imaging parameters (beam energy, dwell time, etc.) on the image contrast were investigated. We demonstrate a similar relationship for both the helium ion microscope Everhart-Thornley and scanning electron microscope Inlens detectors between the contrast of the images and the Ga + density and imaging parameters. These results also show that dynamic charging effects have a significant impact on the quantification of the helium ion microscope and scanning electron microscope contrast. © 2017 The Authors Journal of Microscopy © 2017 Royal Microscopical Society.

  9. Time-resolved scanning tunnelling microscopy

    NARCIS (Netherlands)

    van Houselt, Arie; Zandvliet, Henricus J.W.

    2010-01-01

    Scanning tunneling microscopy has revolutionized our ability to image, study, and manipulate solid surfaces on the size scale of atoms. One important limitation of the scanning tunneling microscope (STM) is, however, its poor time resolution. Recording a standard image with a STM typically takes

  10. A SCANNING ELECTRON MICROSCOPIC STUDY OF HYPERCEMENTOSIS

    OpenAIRE

    Pinheiro, Beth?nia Camargo; Pinheiro, Tiago Novaes; Capelozza, Ana L?cia Alvarez; Consolaro, Alberto

    2008-01-01

    The purpose of this study was to evaluate morphological characteristics of teeth with hypercementosis that are relevant to endodontic practice. Twenty-eight extracted teeth with hypercementosis had their root apexes analyzed by scanning electron microscopy (SEM). The teeth were divided according to tooth groups and type of hypercementosis. The following aspects were examined under SEM: the contour and regularity of the root surface; presence of resorption; presence and number of apical forami...

  11. Dental Wear: A Scanning Electron Microscope Study

    Directory of Open Access Journals (Sweden)

    Luca Levrini

    2014-01-01

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

  12. A scanning electron microscopic study of hypercementosis

    Directory of Open Access Journals (Sweden)

    Bethânia Camargo Pinheiro

    2008-12-01

    Full Text Available The purpose of this study was to evaluate morphological characteristics of teeth with hypercementosis that are relevant to endodontic practice. Twenty-eight extracted teeth with hypercementosis had their root apexes analyzed by scanning electron microscopy (SEM. The teeth were divided according to tooth groups and type of hypercementosis. The following aspects were examined under SEM: the contour and regularity of the root surface; presence of resorption; presence and number of apical foramina, and the diameter of the main foramen. The progression of club shape hypercementosis was directly associated with the presence of foramina and apical foramen obstruction. Cases of focal hypercementosis presented foramina on the surface, even when sidelong located in the root. Circular cementum hyperplasia form was present in 2 out of 3 residual roots, which was the highest proportion among the tooth types. The detection of a large number of foramina in the apical third of teeth with hypercementosis or even the possible existence of apical foramen obliteration contributes to understand the difficulties faced during endodontic treatment of these cases.

  13. A scanning electron microscopic study of hypercementosis.

    Science.gov (United States)

    Pinheiro, Bethânia Camargo; Pinheiro, Tiago Novaes; Capelozza, Ana Lúcia Alvarez; Consolaro, Alberto

    2008-01-01

    The purpose of this study was to evaluate morphological characteristics of teeth with hypercementosis that are relevant to endodontic practice. Twenty-eight extracted teeth with hypercementosis had their root apexes analyzed by scanning electron microscopy (SEM). The teeth were divided according to tooth groups and type of hypercementosis. The following aspects were examined under SEM: the contour and regularity of the root surface; presence of resorption; presence and number of apical foramina, and the diameter of the main foramen. The progression of club shape hypercementosis was directly associated with the presence of foramina and apical foramen obstruction. Cases of focal hypercementosis presented foramina on the surface, even when sidelong located in the root. Circular cementum hyperplasia form was present in 2 out of 3 residual roots, which was the highest proportion among the tooth types. The detection of a large number of foramina in the apical third of teeth with hypercementosis or even the possible existence of apical foramen obliteration contributes to understand the difficulties faced during endodontic treatment of these cases.

  14. AN ANTHOLOGY OF THE DISTINGUISHED ACHIEVEMENTS IN A SCIENCE AND TECHNIQUE. PART 23: INVENTION OF MICROSCOPE AND STUDY OF MICROSCOPIC WORLD

    Directory of Open Access Journals (Sweden)

    M.I. Baranov

    2014-12-01

    Full Text Available A short essay is resulted from world history of invention of microscopes. The basic types of microscopes are described; directions and some results of their application are indicated at the study of microscopic world.

  15. AN ANTHOLOGY OF THE DISTINGUISHED ACHIEVEMENTS IN A SCIENCE AND TECHNIQUE. PART 23: INVENTION OF MICROSCOPE AND STUDY OF MICROSCOPIC WORLD

    OpenAIRE

    M.I. Baranov

    2014-01-01

    A short essay is resulted from world history of invention of microscopes. The basic types of microscopes are described; directions and some results of their application are indicated at the study of microscopic world.

  16. Electron Tunneling in Lithium Ammonia Solutions Probed by Frequency-Dependent Electron-Spin Relaxation Studies

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T.J.; Harmer, Jeffrey; Freed, Jack H.; Edwards, Peter P.

    2012-01-01

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T1) and spin-spin (T2) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multi-exponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1–10)×10−12 s over a temperature range 230–290K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a timescale of ca. 10−13 s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great potential

  17. Electron tunneling in lithium-ammonia solutions probed by frequency-dependent electron spin relaxation studies.

    Science.gov (United States)

    Maeda, Kiminori; Lodge, Matthew T J; Harmer, Jeffrey; Freed, Jack H; Edwards, Peter P

    2012-06-06

    Electron transfer or quantum tunneling dynamics for excess or solvated electrons in dilute lithium-ammonia solutions have been studied by pulse electron paramagnetic resonance (EPR) spectroscopy at both X- (9.7 GHz) and W-band (94 GHz) frequencies. The electron spin-lattice (T(1)) and spin-spin (T(2)) relaxation data indicate an extremely fast transfer or quantum tunneling rate of the solvated electron in these solutions which serves to modulate the hyperfine (Fermi-contact) interaction with nitrogen nuclei in the solvation shells of ammonia molecules surrounding the localized, solvated electron. The donor and acceptor states of the solvated electron in these solutions are the initial and final electron solvation sites found before, and after, the transfer or tunneling process. To interpret and model our electron spin relaxation data from the two observation EPR frequencies requires a consideration of a multiexponential correlation function. The electron transfer or tunneling process that we monitor through the correlation time of the nitrogen Fermi-contact interaction has a time scale of (1-10) × 10(-12) s over a temperature range 230-290 K in our most dilute solution of lithium in ammonia. Two types of electron-solvent interaction mechanisms are proposed to account for our experimental findings. The dominant electron spin relaxation mechanism results from an electron tunneling process characterized by a variable donor-acceptor distance or range (consistent with such a rapidly fluctuating liquid structure) in which the solvent shell that ultimately accepts the transferring electron is formed from random, thermal fluctuations of the liquid structure in, and around, a natural hole or Bjerrum-like defect vacancy in the liquid. Following transfer and capture of the tunneling electron, further solvent-cage relaxation with a time scale of ∼10(-13) s results in a minor contribution to the electron spin relaxation times. This investigation illustrates the great

  18. Histological and electron microscopic study of the postulated ...

    African Journals Online (AJOL)

    kemrilib

    CL; Wang H and Heber D. Bioavailability and antioxidant effect of epigallocatechin gallate administered in purified form versus as green tea extract in healthy individuals. Journal of Nutritional. Biochemistry. 2005; 16:610-6. 13. Ahmed A & Hosney S. Light and electron microscopic study of the effect of furosemide on the liver ...

  19. Evaluation of the Influence Caused by Tunnel Construction on Groundwater Environment: A Case Study of Tongluoshan Tunnel, China

    Directory of Open Access Journals (Sweden)

    Jian Liu

    2015-01-01

    Full Text Available Problems related to water inflow during tunnel construction are challenging to designers, workers, and management departments, as they can threaten tunneling project from safety, time, and economic aspects. Identifying the impacts on groundwater environment resulting from tunnel drainage and making a correct assessment before tunnel construction is essential to better understand troubles that would be encountered during tunnel excavation and helpful to adopt appropriate countermeasures to minimize the influences. This study presents an indicator system and quantifies each indicator of Tongluoshan tunnel, which is located in southwest China with a length of 5.2 km and mainly passes through carbonate rocks and sandstones, based on field investigation and related technological reports. Then, an evaluation is made using fuzzy comprehensive assessment method, with a result showing that it had influenced the local groundwater environment at a moderate degree. Information fed back from environmental investigation and hydrologic monitoring carried out during the main construction period proves the evaluation, as the flow of some springs and streams located beside the tunnel route was found experiencing an apparent decline.

  20. Spectroscopy of surface adsorbed molecules (scanning tunneling microscopy). Progress report, May 1, 1985-April 30, 1986

    International Nuclear Information System (INIS)

    Coleman, R.V.

    1986-01-01

    A review of the scanning tunneling microscopy program is given. This article contains a description of the design and fabrication of the microscope in addition to description of studies which use the microscope: studies of charge-density waves and studies of tunnel junctions doped with metals and semiconductors. 48 refs., 26 figs

  1. Wrist immobilization after carpal tunnel release: a prospective study.

    Science.gov (United States)

    Martins, Roberto S; Siqueira, Mario G; Simplício, Hougelli

    2006-09-01

    This prospective study evaluates the possible advantages of wrist immobilization after open carpal tunnel release comparing the results of two weeks immobilization and no immobilization. Fifty two patients with idiopathic carpal tunnel syndrome were randomly selected in two groups after open carpal tunnel release. In one group (A, n=26) the patients wore a neutral-position wrist splint continuously for two weeks. In the other group (B, n=26) no wrist immobilization was used. Clinical assessment was done pre-operatively and at 2 weeks follow-up and included the two-point discrimination test at the second finger and two questionnaires as an outcome measurement of symptoms severity and intensity. All the patients presented improvement in the postoperative evaluations in the three analyzed parameters. There was no significant difference between the two groups for any of the outcome measurements at the final follow-up. We conclude that wrist immobilization in the immediate post-operative period have no advantages when compared with no immobilization in the end result of carpal tunnel release.

  2. Morphological and microscopic identification studies of Cordyceps and its counterfeits

    Directory of Open Access Journals (Sweden)

    Hui-juan Liu

    2011-10-01

    Full Text Available Macroscopic and microscopic studies were applied to distinguish Cordyceps sinensis (Berk. Sacc. and its 5 common counterfeits. Transverse sections of stroma and larvae and surface sections of stroma of C. sinensis, Cordyceps gunnii, Cordyceps barnesii, Cordyceps gracilis, Cordyceps liangshanensis and Cordyceps militaris were examined and their morphological and microscopic features photographed. The main morphological and microscopic features of the 6 species of Cordyceps were basically similar except for certain diagnostic differences. These included macroscopic differences from C. sinensis as follows: the stroma of C. gunnii is stout and rough with sterile bulgy or branched apex; the larvae of C. barnesii has a pair of teeth on the head; the stroma of C. liangshanensi is thread-like; C. gracilis is without stroma; and C. militaris is without larvae. There were also microscopic differences: from C. sinensis as follows: the stroma of C. barnesii is without perithecia; C. gunnii, C. liangshanensis and C. gracilis are without bristles on the larva body. These differences allow C. sinensis and its counterfeits to be easily distinguished.

  3. Design and performance of an ultra-high vacuum spin-polarized scanning tunneling microscope operating at 30 mK and in a vector magnetic field

    Science.gov (United States)

    von Allwörden, Henning; Eich, Andreas; Knol, Elze J.; Hermenau, Jan; Sonntag, Andreas; Gerritsen, Jan W.; Wegner, Daniel; Khajetoorians, Alexander A.

    2018-03-01

    We describe the design and performance of a scanning tunneling microscope (STM) that operates at a base temperature of 30 mK in a vector magnetic field. The cryogenics is based on an ultra-high vacuum (UHV) top-loading wet dilution refrigerator that contains a vector magnet allowing for fields up to 9 T perpendicular and 4 T parallel to the sample. The STM is placed in a multi-chamber UHV system, which allows in situ preparation and exchange of samples and tips. The entire system rests on a 150-ton concrete block suspended by pneumatic isolators, which is housed in an acoustically isolated and electromagnetically shielded laboratory optimized for extremely low noise scanning probe measurements. We demonstrate the overall performance by illustrating atomic resolution and quasiparticle interference imaging and detail the vibrational noise of both the laboratory and microscope. We also determine the electron temperature via measurement of the superconducting gap of Re(0001) and illustrate magnetic field-dependent measurements of the spin excitations of individual Fe atoms on Pt(111). Finally, we demonstrate spin resolution by imaging the magnetic structure of the Fe double layer on W(110).

  4. Virtual reality microscope versus conventional microscope regarding time to diagnosis: an experimental study.

    Science.gov (United States)

    Randell, Rebecca; Ruddle, Roy A; Mello-Thoms, Claudia; Thomas, Rhys G; Quirke, Phil; Treanor, Darren

    2013-01-01

      To create and evaluate a virtual reality (VR) microscope that is as efficient as the conventional microscope, seeking to support the introduction of digital slides into routine practice.   A VR microscope was designed and implemented by combining ultra-high-resolution displays with VR technology, techniques for fast interaction, and high usability. It was evaluated using a mixed factorial experimental design with technology and task as within-participant variables and grade of histopathologist as a between-participant variable. Time to diagnosis was similar for the conventional and VR microscopes. However, there was a significant difference in the mean magnification used between the two technologies, with participants working at a higher level of magnification on the VR microscope.   The results suggest that, with the right technology, efficient use of digital pathology for routine practice is a realistic possibility. Further work is required to explore what magnification is required on the VR microscope for histopathologists to identify diagnostic features, and the effect on this of the digital slide production process. © 2012 Blackwell Publishing Limited.

  5. Fabrication of ultra-thin cerium oxide layers on Ru(0001) single crystal surfaces. Scanning tunneling microscopic and photoelectron spectroscopic studies on growth, structure and properties; Herstellung ultraduenner Ceroxidschichten auf Ru(0001)-Einkristallflaechen. Rastertunnelmikroskopische und photoelektronenspektroskopische Untersuchungen zu Wachstum, Struktur und Eigenschaften

    Energy Technology Data Exchange (ETDEWEB)

    Bouchtaoui, Mustapha

    2016-12-07

    The thesis at hand aims at a study of structure and properties of well-defined ultrathin CeO{sub 2} films supported on Ru(0001). Such systems may serve as model systems in heterogenous catalysis. The epitaxial growth of ceria films on Ru(0001) surface has been achieved by electron beam evaporation of metal Cer at low background oxygen pressure of 10{sup -6} mbar under ultrahigh-vacuum conditions at room temperature. Cerium oxide qualifies for proper oxygen-storage in oxidation reactions, and hence it widely used in heterogenous catalysis. The oxidation begins with the adsorption of CO on the CeO{sub 2}(111) surface, and it ends with participation of lattice oxygen leading to vacancy formation and CO{sub 2} desorption. We investigate the geometric structure by means of scanning tunneling microscopy and low energy electron diffraction. The coverage of 2.5 monolayers (ML) was sufficient to cover the substrate almost completely. We further analysed the interaction of CO with the CeO{sub 2}/Ru(0001) and the Pt/CeO{sub 2}/Ru(0001) systems. During the interaction process the ratio of Ce{sup 4+} and Ce{sup 3+} changes significantly. This ratio change as well as the effect of Pt evaporated onto the surface with respect to the reducibility of CeO{sub 2}/Ru(0001) in CO environment has been studied by X-ray photoemission spectroscopy and it has been confirmed with thermal desorption spectroscopy. It is revealed that the Pt-Nanoparticles with a height from 7.15 Aa to 9.73 Aa clearly enhances the reducibility of CeO{sub 2}.

  6. Water Tunnel Studies of Dynamic Wing Flap Effects

    Science.gov (United States)

    2016-06-01

    body airfoil was defined by a conventional body and the TEF as an immersed boundary, getting successful results using the hinge moment of the... measurement experiment in a water tunnel at a low Reynolds number (Re = 5402 to Re7054). In this case, this study addressed micro air vehicle...the computational mesh immersed boundary. Source: [9]. ........11 Figure 3. Flow pattern at the trailing edge with a Gurney flap. Source: [7

  7. Efficacy of oral exfoliative cytology in diabetes mellitus patients: a light microscopic and confocal microscopic study.

    Science.gov (United States)

    Gopal, Deepika; Malathi, N; Reddy, B Thirupathi

    2015-03-01

    Diabetes mellitus (DM) has become a global problem. By monitoring the health status of these individuals, diabetic complications can be prevented. We aimed to analyze alterations in the morphology and cytomorphometry of buccal epithelial cells of type 2 DM patients using oral exfoliative cytology technique and determine its importance in public health screening, diagnosis and monitoring of diabetes mellitus. The study was carried out in 100 type 2 DM patients and 30 healthy individuals. Smears were taken from the right buccal mucosa and stained by the Papanicolaou technique. Staining with Acridine orange was carried out to view qualitative changes with confocal laser scanning microscope (LSM-510 Meta). The cytomorphometry was evaluated using IMAGE PRO PLUS 5.5 software with Evolution LC camera. All findings were statistically analyzed. The results showed that with increase in fasting plasma glucose levels, there is significant increase in nuclear area, decrease in cytoplasmic area, and increase in nuclear cytoplasmic ratio (p diabetes and aid in monitoring of diabetes throughout the lifetime of the patient.

  8. Scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Binnig, G.; Rohrer, H.

    1983-01-01

    Based on vacuum tunneling, a novel type of microscope, the scanning tunneling microscope (STM) was developed. It has an unprecedented resolution in real space on an atomic scale. The authors review the important technical features, illustrate the power of the STM for surface topographies and discuss its potential in other areas of science and technology. (Auth.)

  9. Analytical modelling and experimental studies of SIS tunnel solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Cheknane, Ali [Laboratoire de Valorisation des Energies Renouvelables et Environnements Agressifs, Universite Amar Telidji de Laghouat, BP 37G route de Ghardaia, Laghouat (03000) Algerie (Algeria)], E-mail: cheknanali@yahoo.com

    2009-06-07

    This paper presents an experimental and computational study of semiconductor-insulator-semiconductor (SIS) tunnel solar cells. A transparent and conductive film of thallium trioxide Tl{sub 2}O{sub 3} has been deposited by anodic oxidation onto an n-Si(1 0 0) face to realize the SIS tunnel solar cells based on Si/SiO{sub x}/Tl{sub 2}O{sub 3}. An efficiency of 8.77% has been obtained under an incident power density of 33 mW cm{sup -2} illumination condition. A PSPICE model is implemented. The calculated results show that the theoretical values are in good agreement with experimental data. Moreover, the simulation clearly demonstrates that the performance of the tested device can be significantly improved.

  10. Cathodoluminescence studies of phosphors in a scanning electron microscope

    International Nuclear Information System (INIS)

    Harris, Paul; Den Engelsen, Daniel; Ireland, Terry; Fern, George; Silver, Jack

    2015-01-01

    Cathodoluminescence studies are reported of phosphors in a field emission scanning electron microscope (FESEM). A number of phosphor materials have been studied and exhibited a pronounced comet-like structure at high scan rates, because the particle continued to emit light after the beam had moved onto subsequent pixels. Image analysis has been used to study the loss of brightness along the tail and hence to determine the decay time of the materials. This technique provides a simple and convenient way to study the decay times of individual particles. (paper)

  11. The study of optimal conditions of electrochemical etching of tunnel electron microscopy tungsten tips

    International Nuclear Information System (INIS)

    Anguiano, E.; Aguilar, M.; Olivar, A.I.

    1996-01-01

    We present the experimental results obtained during the study made in the electrochemical etching of tunneling electron microscopy tungsten tips. The experiments was made using DC and two usual electrolytes: KOH and NaOH. For the tip preparation we used a electrochemical cell with stainless steel cathode and the tungsten wire as anode. the electrodes was introduced in a glass recipient containing the electrolytic solution. We study the effects of applied voltage, polish time, tip length and electrolyte concentration as process relevant parameters. The best condition for tip preparation was obtained with a metallurgical microscope and with a SEM.EDX and Auger analysis was made. The results shown the better tips was made with KOH as electrolyte with a limited concentration range (2-4 normal) and applied voltage (2-6 volts) (Author) 20 refs

  12. Topics in recent studies with high-voltage electron microscopes.

    Science.gov (United States)

    Mori, Hirotaro

    2011-01-01

    In this article, topics in recent studies with high-voltage electron microscopes (HVEMs) are reviewed. High-voltage electron microscopy possesses a number of advantages that cannot be afforded by conventional electron microscopy, thus providing a unique microscopy technique in both materials science and biological science. One of these advantages is the capability of continuously observing phenomena using a variety of electron microscopy techniques simultaneously with the introduction of the displacement of atoms from lattice points. This has enabled in-depth studies on such fundamental subjects as the crystalline-to-amorphous-to-crystalline transition, the motion properties of point defects and the one-dimensional diffusion of dislocation loops. Electron tomography studies using HVEMs take advantage of the large observable thickness of a specimen. In addition, by combining different advantages, a number of advanced applications in materials science have been carried out, including analyses of the atomic structure of a reduction-induced reconstructed surface and the atomic mechanism behind the self-catalytic vapor-liquid-solid growth of an oxide nanowire. As long as excellent and invaluable studies that cannot be carried out without HVEMs appear in succession, it is necessary to make the utmost efforts to improve these microscopes.

  13. Microscopic study of rock for estimating long-term behavior

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki

    2004-02-01

    Micro-structure of rock plays an essential role for their long-term behavior. For understanding long-term characteristics of granite we here present the followings: 1) observation of microcrack initiation and propagation by Conforcal Laser Scanning Microscope (CLSM) under uniaxial compression (before loading and at each loading stage), 2) characterization of the mechanism of microcrack initiation and propagation observed by stereoscopic microscope under uniaxial/triaxial compression and relaxation tests, and 3) a study of strong discontinuity analysis included in the homogenization theory to predict the long-term behavior of micro/macro-level stress for granite. First, CLSM was used to acquire clearly focused three-dimensional images of granite specimens, and observed the change of microscale structure including the mineral configuration under applying uniaxial compression stress. Then though microcracks have ever thought to be initiated and propagated on intergranular boundaries, we understand through the CLSM observation that new microcracks are generated from the ends of pre-existing cracks which are distributed in quartz and biotite. Second, we showed the results of stress-relaxation test of granite specimens observed by an optical microscope under water-saturated triaxial compression condition. Since microcrack generation and propagation play an essential role to predict the long-term behavior of rock, we managed the experiments with careful attention of 1) keeping constant edge-displacement and constant strain in the whole specimen accurately, and 2) measuring the relaxed stress exactly. Next, in order to simulate the experimental results which indicate that initiation and propagation of microcracks control the stress-relaxation phenomenon, we introduce a homogenization analysis procedure together with the strong discontinuity analysis which has recently established the mechanical implication and mathematical foundation. The numerical results show that we can

  14. ZEDEX - A study of damage and disturbance from tunnel excavation by blasting and tunnel boring

    Energy Technology Data Exchange (ETDEWEB)

    Emsley, S. [Golder Associates, Maidenhead (United Kingdom); Olsson, Olle; Stenberg, L. [Swedish Nuclear Fuel and Waste Co., Figeholm (Sweden); Alheid, H.J. [Federal Inst. for Geosciences and Natural Resources, Hannover (Germany); Falls, S. [Queens Univ., Kingston, ON (Canada)

    1997-12-01

    The objectives of the ZEDEX project were to understand the mechanical behaviour of the excavation disturbed zone (EDZ) with respect to its origin, character, magnitude of property change, extent and its dependence on excavation method. Excavation with normal smooth blasting, blasting with low shock explosives and tunnel boring were studied. The drifts are located at Aespoe at a depth of 420 m, the profiles are circular and 5 m in diameter. The results have shown that there is a damaged zone, close to the drift wall dominated by changes in rock properties which are irreversible, and that there is a disturbed zone beyond the damaged zone that is dominated by changes in stress state and mainly reversible. There is no distinct boundary between the two zones. The results from ZEDEX indicate that the role of the EDZ as a preferential pathway to radionuclide transport is limited to the damaged zone. The extent of the damaged zone can be limited through application of appropriate excavation methods. By limiting the extent of the damaged zone it should also be feasible to block pathways in the damaged zone by plugs placed at strategic locations 68 refs, 92 figs, 31 tabs

  15. ZEDEX - A study of damage and disturbance from tunnel excavation by blasting and tunnel boring

    International Nuclear Information System (INIS)

    Emsley, S.; Olsson, Olle; Stenberg, L.; Alheid, H.J.; Falls, S.

    1997-12-01

    The objectives of the ZEDEX project were to understand the mechanical behaviour of the excavation disturbed zone (EDZ) with respect to its origin, character, magnitude of property change, extent and its dependence on excavation method. Excavation with normal smooth blasting, blasting with low shock explosives and tunnel boring were studied. The drifts are located at Aespoe at a depth of 420 m, the profiles are circular and 5 m in diameter. The results have shown that there is a damaged zone, close to the drift wall dominated by changes in rock properties which are irreversible, and that there is a disturbed zone beyond the damaged zone that is dominated by changes in stress state and mainly reversible. There is no distinct boundary between the two zones. The results from ZEDEX indicate that the role of the EDZ as a preferential pathway to radionuclide transport is limited to the damaged zone. The extent of the damaged zone can be limited through application of appropriate excavation methods. By limiting the extent of the damaged zone it should also be feasible to block pathways in the damaged zone by plugs placed at strategic locations

  16. Model uncertainty of various settlement estimation methods in shallow tunnels excavation; case study: Qom subway tunnel

    Science.gov (United States)

    Khademian, Amir; Abdollahipour, Hamed; Bagherpour, Raheb; Faramarzi, Lohrasb

    2017-10-01

    In addition to the numerous planning and executive challenges, underground excavation in urban areas is always followed by certain destructive effects especially on the ground surface; ground settlement is the most important of these effects for which estimation there exist different empirical, analytical and numerical methods. Since geotechnical models are associated with considerable model uncertainty, this study characterized the model uncertainty of settlement estimation models through a systematic comparison between model predictions and past performance data derived from instrumentation. To do so, the amount of surface settlement induced by excavation of the Qom subway tunnel was estimated via empirical (Peck), analytical (Loganathan and Poulos) and numerical (FDM) methods; the resulting maximum settlement value of each model were 1.86, 2.02 and 1.52 cm, respectively. The comparison of these predicted amounts with the actual data from instrumentation was employed to specify the uncertainty of each model. The numerical model outcomes, with a relative error of 3.8%, best matched the reality and the analytical method, with a relative error of 27.8%, yielded the highest level of model uncertainty.

  17. Microscopic study of rock for estimating long-term behavior

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki

    1997-03-01

    One must consider micro-structures of rock and rock mass in order to predict the long-term behavior for more than ten thousand years. First we observe the micro-crack distribution of granite which is commonly distributed in Japan, and is widely used for several structures. The creep under constant load and the relaxation under constant displacement are typical time dependent phenomena, and we performed a series of relaxation tests under microscope observation in laboratory. The specimen that is preserved in water is granite as mentioned above. The aim of this experiment is to observe the sequential propagation of micro-cracks and its affect to the macroscopic response of the rock material under relaxation state. Next, a viscoelastic homogenization method is applied for analyzing the behavior of granite that is composed of several kinds of minerals (i.e., a polycrystalline material). The homogenization method developed for analyzing mechanics of composite materials is a mathematical theory that can describe the macroscopic behavior accounting for the microscopic characteristics with periodic microstructures. In this study, it is applied to a polycrystalline rock which involves a few minerals and micro-cracks. Furthermore, it is required to apply the homogenization analysis for rock materials which show a nonlinear time dependent behavior, so we develop a new elasto-visco-plastic homogenization theory, and its validity is checked for some ground structures made by clay. (author)

  18. Diesel bus emissions measured in a tunnel study.

    Science.gov (United States)

    Jamriska, Milan; Morawska, Lidia; Thomas, Steven; He, Congrong

    2004-12-15

    The emission factors of a bus fleet consisting of approximately 300 diesel-powered buses were measured in a tunnel study under well-controlled conditions during a 2-d monitoring campaign in Brisbane. Particle number and mass concentration levels of submicrometer particles and PM2.5 were monitored by SMPS and DustTrak instruments at the tunnel's entrance and exit, respectively. Correlation between DustTrak and TEOM response to diesel emissions was assessed, and the DustTrak results were recalculated into TEOM equivalent data. The mean value of the number and mass emission factors was (3.11+/-2.41) x 10(14) particles km(-1) for submicrometer particles and 583+/-451 mg km(-1) for PM2.5 (DustTrak), respectively. TEOM PM2.5 equivalent emission factor was 267+/-207 mg km(-1). The results are in good agreement with the emission factors determined from steady-state dynamometer testing of 12 buses from the same Brisbane City bus fleet. The results indicate that when carefully designed, both approaches, the dynamometer and on-road studies, can provide comparable results, applicable for the assessment of the effect of traffic emissions on airborne particle pollution. A brief overview of emission factors determined from other on-road and dynamometer studies reported in the literature as well as with the regulatory values used for the vehicle emission inventory assessment is presented and compared with the results obtained in this study.

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

    International Nuclear Information System (INIS)

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

    1983-01-01

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

  20. Electron holography study on the microstructure of magnetic tunnelling junctions

    International Nuclear Information System (INIS)

    Xu, Q.Y.; Wang, Y.G.; You, B.; Du, J.; Hu, A.; Zhang, Z.

    2004-01-01

    Electron holography was applied to study the microstructure evolution of magnetic tunnelling junctions (MTJs) CoFe/AlO x /Co annealed at different temperatures. A mean inner potential barrier was observed in the as-deposited MTJ sample, while it was changed to a potential well after a 200 deg. C or a 400 deg. C annealing. It is suggested that the oxygen atoms were redistributed during the annealing, which left metallic atoms acting as acceptors to confine the electrons, leading to the decrease of the potential of the AlO x barrier layer. The results suggest that the electron holography may be a useful tool for the study of the microstructure of amorphous materials

  1. Study of the geometrical resonances of superconducting tunnel junctions

    DEFF Research Database (Denmark)

    Sørensen, O. Hoffmann; Finnegan, T.F.; Pedersen, Niels Falsig

    1973-01-01

    The resonant cavity structure of superconducting Sn-Sn-oxide-Sn tunnel junctions has been investigated via photon-assisted quasiparticle tunneling. We find that the temperature-dependent losses at 35 GHz are determined by the surface resistance of the Sn films for reduced temperatures between 0.5...

  2. Preliminary study on the transport of hazardous materials through tunnels.

    Science.gov (United States)

    Bubbico, Roberto; Di Cave, Sergio; Mazzarotta, Barbara; Silvetti, Barbara

    2009-11-01

    The risk associated to road and rail transportation of some hazardous materials along two routes, one including a significant portion in tunnels, and the other following the same path, but running completely in the open, is assessed. The results show that, for rail transport, no particular risk increase or mitigation is associated to the circulation of the dangerous goods through tunnels; on the contrary, for road transport, a risk increase is generally observed in the presence of tunnels. However, for LPG, the risk curve in the open lies above that in tunnels in the high frequency-low fatality zone, according to the different evolution of the accidental scenarios in the tunnel (assuming no ventilation). The transportation of liquefied nitrogen, not hazardous in the open but potentially asphyxiating in a tunnel, gives rise to a negligible risk when performed by rail, but to a not negligible one, when performed by road. These preliminary results focused on the risk for the exposed population, suggest that it may be unnecessary to limit dangerous goods circulation through rail tunnels, while, at least for some types of dangerous goods, the circulation through road tunnels may be allowed/forbidden based on the results of a specific risk analysis.

  3. Microscopic study of neutron-rich dysprosium isotopes

    International Nuclear Information System (INIS)

    Vargas, Carlos E.; Velazquez, Victor; Lerma, Sergio

    2013-01-01

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, γ and β bands, and their B(E2) transition strengths in 160-168 Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of γ and β bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus 170 Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  4. Microscopic studies of nonlocal spin dynamics and spin transport (invited)

    Energy Technology Data Exchange (ETDEWEB)

    Adur, Rohan; Du, Chunhui; Cardellino, Jeremy; Scozzaro, Nicolas; Wolfe, Christopher S.; Wang, Hailong; Herman, Michael; Bhallamudi, Vidya P.; Pelekhov, Denis V.; Yang, Fengyuan; Hammel, P. Chris, E-mail: hammel@physics.osu.edu [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States)

    2015-05-07

    Understanding the behavior of spins coupling across interfaces in the study of spin current generation and transport is a fundamental challenge that is important for spintronics applications. The transfer of spin angular momentum from a ferromagnet into an adjacent normal material as a consequence of the precession of the magnetization of the ferromagnet is a process known as spin pumping. We find that, in certain circumstances, the insertion of an intervening normal metal can enhance spin pumping between an excited ferromagnetic magnetization and a normal metal layer as a consequence of improved spin conductance matching. We have studied this using inverse spin Hall effect and enhanced damping measurements. Scanned probe magnetic resonance techniques are a complementary tool in this context offering high resolution magnetic resonance imaging, localized spin excitation, and direct measurement of spin lifetimes or damping. Localized magnetic resonance studies of size-dependent spin dynamics in the absence of lithographic confinement in both ferromagnets and paramagnets reveal the close relationship between spin transport and spin lifetime at microscopic length scales. Finally, detection of ferromagnetic resonance of a ferromagnetic film using the photoluminescence of nitrogen vacancy spins in neighboring nanodiamonds demonstrates long-range spin transport between insulating materials, indicating the complexity and generality of spin transport in diverse, spatially separated, material systems.

  5. Microscopic study of neutron-rich dysprosium isotopes

    Energy Technology Data Exchange (ETDEWEB)

    Vargas, Carlos E. [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico); Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Velazquez, Victor [Universidad Nacional Autonoma de Mexico, Facultad de Ciencias, Apartado Postal 70-542, Mexico D.F. (Mexico); Lerma, Sergio [Universidad Veracruzana, Facultad de Fisica e Inteligencia Artificial, Xalapa (Mexico)

    2013-01-15

    Microscopic studies in heavy nuclei are very scarce due to large valence spaces involved. This computational problem can be avoided by means of the use of symmetry-based models. Ground-state, {gamma} and {beta} bands, and their B(E2) transition strengths in {sup 160-168}Dy isotopes, are studied in the framework of the pseudo-SU(3) model which includes the preserving symmetry Q . Q term and the symmetry-breaking Nilsson and pairing terms, systematically parametrized. Additionally, three rotor-like terms are considered, whose free parameters, fixed for all members of the chain, are used to fine tune the moment of inertia of rotational bands and the band head of {gamma} and {beta} bands. The model succesfully describes in a systematic way rotational features in these nuclei and allows to extrapolate toward the midshell nucleus {sup 170}Dy. The results presented show that it is possible to study a full chain of isotopes or isotones in the region with the present model. (orig.)

  6. Study of the Integration of the CNU-TS-1 Mobile Tunnel Monitoring System.

    Science.gov (United States)

    Du, Liming; Zhong, Ruofei; Sun, Haili; Zhu, Qiang; Zhang, Zhen

    2018-02-01

    A rapid, precise and automated means for the regular inspection and maintenance of a large number of tunnels is needed. Based on the depth study of the tunnel monitoring method, the CNU-TS-1 mobile tunnel monitoring system (TS1) is developed and presented. It can efficiently obtain the cross-sections that are orthogonal to the tunnel in a dynamic way, and the control measurements that depend on design data are eliminated. By using odometers to locate the cross-sections and correcting the data based on longitudinal joints of tunnel segment lining, the cost of the system has been significantly reduced, and the interval between adjacent cross-sections can reach 1-2 cm when pushed to collect data at a normal walking speed. Meanwhile, the relative deformation of tunnel can be analyzed by selecting cross-sections from original data. Through the measurement of the actual tunnel, the applicability of the system for tunnel deformation detection is verified, and the system is shown to be 15 times more efficient than that of the total station. The simulation experiment of the tunnel deformation indicates that the measurement accuracy of TS1 for cross-sections is 1.1 mm. Compared with the traditional method, TS1 improves the efficiency as well as increases the density of the obtained points.

  7. Study of the Integration of the CNU-TS-1 Mobile Tunnel Monitoring System

    Directory of Open Access Journals (Sweden)

    Liming Du

    2018-02-01

    Full Text Available A rapid, precise and automated means for the regular inspection and maintenance of a large number of tunnels is needed. Based on the depth study of the tunnel monitoring method, the CNU-TS-1 mobile tunnel monitoring system (TS1 is developed and presented. It can efficiently obtain the cross-sections that are orthogonal to the tunnel in a dynamic way, and the control measurements that depend on design data are eliminated. By using odometers to locate the cross-sections and correcting the data based on longitudinal joints of tunnel segment lining, the cost of the system has been significantly reduced, and the interval between adjacent cross-sections can reach 1–2 cm when pushed to collect data at a normal walking speed. Meanwhile, the relative deformation of tunnel can be analyzed by selecting cross-sections from original data. Through the measurement of the actual tunnel, the applicability of the system for tunnel deformation detection is verified, and the system is shown to be 15 times more efficient than that of the total station. The simulation experiment of the tunnel deformation indicates that the measurement accuracy of TS1 for cross-sections is 1.1 mm. Compared with the traditional method, TS1 improves the efficiency as well as increases the density of the obtained points.

  8. Somatic Embryos in Catharanthus roseus: A Scanning Electron Microscopic Study

    Directory of Open Access Journals (Sweden)

    Junaid ASLAM

    2014-06-01

    Full Text Available Catharanthus roseus (L. G. Don is an important medicinal plant as it contains several anti-cancerous compounds, like vinblastine and vincristine. Plant tissue culture technology (organogenesis and embryogenesis has currently been used in fast mass propagating raw materials for secondary metabolite synthesis. In this present communication, scanning electron microscopic (SEM study of somatic embryos was conducted and discussed. The embryogenic callus was first induced from hypocotyls of in vitro germinated seeds on which somatic embryos, differentiated in numbers, particularly on 2,4-D (1.0 mg/L Murashige and Skoog (MS was medium. To understand more about the regeneration method and in vitro formed embryos SEM was performed. The SEM study revealed normal somatic embryo origin and development from globular to heart-, torpedo- and then into cotyledonary-stage of embryos. At early stage, the embryos were clustered together in a callus mass and could not easily be detached from the parental tissue. The embryos were often long cylindrical structure with or without typical notch at the tip. Secondary embryos were also formed on primary embryo structure. The advanced cotyledonary embryos showed prominent roots and shoot axis, which germinated into plantlets. The morphology, structure and other details of somatic embryos at various stages were presented.

  9. DEVISING A VISUAL INSPECTION SYSTEM FOR CANAL TUNNELS: PRELIMINARY STUDIES

    Directory of Open Access Journals (Sweden)

    J.-L. Albert

    2013-07-01

    Full Text Available In France, most tunnel canals were built during the 19th and 20th centuries. Maintaining them is not only a matter of heritage preservation but also a question of security. Inspecting tunnel canals is difficult and time consuming, which motivates the development of an image-based surveying system, as already exists for railway or road tunnels. However, while the imaging configuration is similar, referencing the data acquisition device is more difficult in the case of underground waterways, due to the drifts of the inspection barge. In this paper, we introduce the recording prototype we have designed and report the results of the test that were performed in an underground waterway, Niderviller's tunnel, to assess the feasibility of the system. In particular, we give details on the imaging system design. We also analyze the pros and cons of each location method, in terms of costs, practicability, computational burden and accuracy.

  10. Devising a Visual Inspection System for Canal Tunnels: Preliminary Studies

    Science.gov (United States)

    Albert, J.-L.; Charbonnier, P.; Chavant, P.; Foucher, P.; Muzet, V.; Prybyla, D.; Perrin, T.; Grussenmeyer, P.; Guillemin, S.; Koehl, M.

    2013-07-01

    In France, most tunnel canals were built during the 19th and 20th centuries. Maintaining them is not only a matter of heritage preservation but also a question of security. Inspecting tunnel canals is difficult and time consuming, which motivates the development of an image-based surveying system, as already exists for railway or road tunnels. However, while the imaging configuration is similar, referencing the data acquisition device is more difficult in the case of underground waterways, due to the drifts of the inspection barge. In this paper, we introduce the recording prototype we have designed and report the results of the test that were performed in an underground waterway, Niderviller's tunnel, to assess the feasibility of the system. In particular, we give details on the imaging system design. We also analyze the pros and cons of each location method, in terms of costs, practicability, computational burden and accuracy.

  11. Molecular modeling study on tunnel behavior in different histone deacetylase isoforms.

    Directory of Open Access Journals (Sweden)

    Sundarapandian Thangapandian

    Full Text Available Histone deacetylases (HDACs have emerged as effective therapeutic targets in the treatment of various diseases including cancers as these enzymes directly involved in the epigenetic regulation of genes. However the development of isoform-selective HDAC inhibitors has been a challenge till date since all HDAC enzymes possess conserved tunnel-like active site. In this study, using molecular dynamics simulation we have analyzed the behavior of tunnels present in HDAC8, 10, and 11 enzymes of class I, II, and IV, respectively. We have identified the equivalent tunnel forming amino acids in these three isoforms and found that they are very much conserved with subtle differences to be utilized in selective inhibitor development. One amino acid, methionine of HDAC8, among six tunnel forming residues is different in isoforms of other classes (glutamic acid (E in HDAC10 and leucine (L in HDAC 11 based on which mutations were introduced in HDAC11, the less studied HDAC isoform, to observe the effects of this change. The HDAC8-like (L268M mutation in the tunnel forming residues has almost maintained the deep and narrow tunnel as present in HDAC8 whereas HDAC10-like (L268E mutation has changed the tunnel wider and shallow as observed in HDAC10. These results explained the importance of the single change in the tunnel formation in different isoforms. The observations from this study can be utilized in the development of isoform-selective HDAC inhibitors.

  12. Electron microscopic study on radiosensitivity of uterine cervical cancer

    International Nuclear Information System (INIS)

    Iwai, Shoji; Shiozawa, Kyuyo; Tsukamoto, Takashi; Noguchi, Hiroshi; Tsukahara, Yoshiharu

    1974-01-01

    The effects of 1000 R of tele-cobalt upon the changes in the primary lesions of uterine cervical cancer with time were studied with an electron microscope. In addition, twenty cases which were proven to have cancer tissues (10 cases of IInd stage of cancer, 8 cases of IIIrd stage of cancer and 2 cases of IVth stage of cancer) were studied. Four cases were favourably sensitive, 7 cases moderately sensitive and 9 cases unfavourably sensitive to radiation. In favourably radio-sensitive cases, the changes in the cancer cells first appeared in the nucleus. There were other changes such as local clumping of chromatin and, specifically, vacuolization of the nucleus. The changes in the endoplasmic reticulum appeared somewhat late. In addition, the disturbance of mitochondria and the decrease or disappearance of ribosomes were specifically due to radiation injury. From the point of view of changes with time, Golgi's apparatus was enlarged and the membrane of the endoplasmic reticulum was degenerated at the 1st day. At the 3rd day, vacuolization of the nucleus appeared, the nuclear corpuscles were increased, the nucleoplasm became thin, and mitochondria was enlarged and degenerated. At the 5th day, the nuclear membrane disappeared, the nucleus was destroyed, large vacuolization of the endoplasmic reticulum was seen, free ribosomes were decreased, and changes around the endoplasmic reticulum were observed. At the 7th day, collagen around the endoplasmic reticulum appeared. In favourably radiosensitive cases, individual tumor cells showed the same degeneration, which fairly corresponded to that evaluated by the histological observation. The disturbance of the cells was caused by radiation, so-called ''burning'' of the cells. Radiation protection of the cells against burning was considered in terms of their radiosensitivity. (K. SERIZAWA)

  13. Microscopic Study of Surface Microtopographic Characteristics of Dental Implants

    Science.gov (United States)

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

    2016-01-01

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

  14. microscopical studies on the leaves of momordica charantia

    African Journals Online (AJOL)

    Momordica charantia Linn. is a monoecious plant of the family Cucurbitaceae. It is known to contain various chemical constituents, which has the hypoglycaemic activity. This work reports the microscopical and even the macroscopical features of the leaves of this plant species. Features among which identified were the ...

  15. Analysis of an underground structure settlement risk due to tunneling- A case study from Tabriz, Iran

    Directory of Open Access Journals (Sweden)

    Mohammad Javad Vahdatirad

    2010-05-01

    Full Text Available The tunnel of the Tabriz urban railway line 2 (TURL2, Iran, will pass through an underground commercial center onits way. Too little distance between the tunnel crown and the underground structure foundation will probably cause collapseor excessive settlement during the tunnel construction based on studied geotechnical conditions of the region. In this paper,a method of risk level assessment for various types of structures, such as frame and masonry structures, and various typesof foundation, such as continuous and isolated, is well defined and the risk level is classified. Moreover, the value of theunderground commercial center structure settlement is estimated using both empirical and numerical methods. The settlementrisk level of the commercial center structure is determined based on presented definitions about risk classification ofvarious types of structures. Consequently, tunneling processes in this section need a special monitoring system and consolidationmeasures before the passage of a tunnel boring machine.

  16. Scanning tunneling microscopy study of GaAs(001) surfaces

    Science.gov (United States)

    Xue, Qi-Kun; Hashizume, T.; Sakurai, T.

    1999-03-01

    While GaAs(001) is the most commonly used substrate in fabrication of wireless and opto-electronic devices based on III-V compound semiconductors by molecular beam epitaxy (MBE), metallorganic chemical vapor deposition (MOCVD) and related techniques, its surface structure have been disputed since the beginning of development of the techniques. Invention of scanning tunneling microscopy (STM) has revolutionized the approach of surface/interface investigation, contributing greatly in the atomistic understanding of the GaAs surface phases. This paper reviews the STM studies of principal reconstructions, from As-rich c(4×4), 2×4, 2×6 to Ga-rich 4×2 and 4×6, found on the GaAs (001) surface. These studies, together with advanced theoretical efforts, have helped us to establish a unified structural model for various reconstructions, with which we can now explain most of the observations and long-standing controversies in atomic structures and surface stoichiometries.

  17. [Microscopic identification study of western herbs. Part I: Three Echinacea-species roots].

    Science.gov (United States)

    Li, Qin; Chu, Chu; Tan, Zhenfeng; Wang, Yaqiong; Wei, Jiafu; Li, Ping; Zhao, Zhongzhen

    2009-11-01

    To make microscopic identification research of three Echinacea-species roots recorded in the United States Pharmacopeia. The root transverse section and powder of E. angustifolia, E. pallida, and E. purpurea were observed. The main microscopic features were photographed. The main microscopic features of transverse section and powder in three Echinacea-species roots are basically similar, except for some diagnostic differences. The results provide reliable reference for the authentication of raw materials of western herbal studies.

  18. Interdot carrier's transfer via tunneling pathway studied from photoluminescence spectroscopy

    International Nuclear Information System (INIS)

    Rihani, J.; Sallet, V.; Yahyaoui, N.; Harmand, J.C.; Oueslati, M.; Chtourou, R.

    2009-01-01

    Self-assembled InAs quantum dots (QDs) on GaAs(0 0 1) substrate were grown by molecular beam epitaxy (MBE) at a growth temperature of 490 deg. C. Two different families of dots were observed in the atomic force microscopy (AFM) image and ambiguously identified in the photoluminescence (PL) spectra. Temperature-dependent PL study was carried out in the 8-270 K temperature range. The integrated-PL intensity behavior of the two QDs populations was fit with the help of a rate equations model. It is found that the evolutions of the integrated-PL intensity of the two QDs population were governed by two regimes. The first one occurs in the 8-210 K temperature range and reveals an unusual enhancement of the integrated-PL intensity of the larger QDs (LQDs) class. This was attributed to the carrier supplies from the smaller QDs (SQDs) class via the tunneling process. The second one occurs in the 210-270 K temperature range and shows a common quench of the PL signals of the two QDs families, reflecting the same thermal escape mechanism of carriers

  19. Monitored Retrievable Storage conceptual system study: tunnel drywells

    International Nuclear Information System (INIS)

    Unterzuber, R.; Cross, T.E.; Krasicki, B.R.; Lundberg, W.L.

    1983-08-01

    A description of the tunnel drywell storage facility concept is presented with the operations required to handle the spent fuel or high-level wastes and transuranic wastes. A generic Receiving and Handling Facility, provided by PNL, has been used for this study. Modifications to the storage delivery side of the handling facility, necessary to couple the Receiving and Handling Facility with the storage facility, are described. The equipment and support facilities needed for the storage facility are also described. Two separate storage facilities are presented herein: one for all spent fuel storage, and one for storage of high-level waste (HLW) and transuranic waste (TRU). Each facility is described for the capacities and rates defined by PNL in the Concept Technical Performance Criteria and Base Assumptions. Estimates of costs and time-distributions of expenditures have been developed to construct, operate, and decommission the conceptual MRS facilities in mid 1983 dollars, for the base cases given using the cost categories and percentages provided by PNL. Cost estimates and time-distributions of expenditures have also been developed to expand the facility throughput rate from 1800 MTU to 3000 MTU, and to expand the facility storage capacity from 15,000 MTU to 72,000 MTU. The life cycle cost of the facility for the bounding cases of all spent fuel and all HLW and TRU, using the time-distributions of costs developed above and assuming a two percent per year discount rate, are also presented. 2 references, 14 figures, 16 tables

  20. Microscopic study of rock for estimating long-term behavior

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki

    2002-03-01

    Micro-structure of rock plays a essential role for their long-term behavior. For elucidating long-term characteristics of granite we here present the followings: 1) Conforcal Laser Scanning Microscope (LSM) observation of joint surfaces of granite and Fourier analysis, 2) characterization of the mechanism of microcrack initiation and propagation observed by stereoscopic microscope under uniaxial/triaxial compression and relaxation tests, 3) observation of microcrack initiation and propagation by LSM under uniaxial compression, and 4) a viscoelastic homogenization theory to predict the long-term behavior of micro/macro-level stress for granite. Rock image processing and analysis become a fundamental procedure to determine rock surface discontinuities. But the complexity of rock surface discontinuities seems beyond the manual image processing method. In Chapter 2 a Conforcal Laser Scanning Microscope that can acquire three-dimensional images is introduced to observe the rock roughness of a discontinuity. Then, scanning three-dimensional images are changed its data form in order to adapt various image analysis programs, and granitic rock roughness of discontinuities are displayed by graphic images. For example, these datas are analyzed by Discrete Fourier Transformation (DFT) program and Inverse Discrete Fourier Transformation (IDFT) program. Microcrack generation and propagation play an essential role to predict the long-term behavior of rock. In Chapter 3 a progressive development of cracking in granite is revealed by using stereoscopic microscope under triaxial compression condition and by using LSM under uniaxial compression condition. With a viscoelastic theory applied in homogenization method, we can calculate macro behavior of medium influenced by its micro structure by analyse the long-term time-dependent behavior of granite under the same condition to the relaxation experiment. (author)

  1. Studies of Au/SAMs/PEDOT-PSS/Au tunnel junctions

    Science.gov (United States)

    Sun, Nan; Lieberman, Marya; Ruggiero, Steven

    2008-03-01

    We report on tunneling through thin organic films. Junctions of the form: Au/SAMs/Polymer/Au were prepared on electronic-grade Si substrates with Self-Assembled Monolayers (SAMs) including octanedithiol (HS-C8H16-SH) and mercaptohexadecanoic (HS-C15H30-COOH). A transitional conducting polymer film PEDOT-PSS was spun on to the SAMs layer, and junctions were completed with a gold film. X-ray photoelectron spectroscopy (XPS) was employed to monitor the quality of the SAMs films. The electron tunneling properties including dI/dV and d^2I/dV^2 versus bias for the SAMs are discussed.

  2. Geochemical study of acid mine drainage of the Big Lick Tunnel area, Williamstown, PA

    International Nuclear Information System (INIS)

    Tollin, S.

    1993-01-01

    Acid mine drainage in the anthracite region of Pennsylvania continues to be a significant environmental problem. This study examines the acid mine outflow from the Big Lick Tunnel, north of Williamstown, Dauphin County, Pennsylvania. The tunnel drains abandoned mines on the north side of the Big Lick Mountain. Mining ceased in the area circa 1940, and the tunnel has been in operation since that time. The water, soil and stream bed sediment geochemistry has been studied to determine their changes in chemistry over distance. The pH, TDS and metal concentrations were the primary focus. Metal concentrations were determined using an ICP unit. Data indicates the pH of the outflow to range between 6.7 and 7.3 Fe and Mn concentrations are as high as 9.7 ppb. Extensive metal precipitation (''yellow boy'') occurs within the tunnel and for several hundred meters from the mouth of the tunnel. The combination of near neutral pH and high metal concentration suggest that the drainage is in contact with highly alkaline materials prior to discharge from the tunnel. The geology of the area does not suggest bedrock as the possible source of alkaline material. One hypothesis is that the acidic water is reacting with the concrete tunnel and being neutralized. Data also suggests that the Fe precipitates much quicker than the Mn, resulting in a zonation between Fe-rich and Mn-rich sediments along the length of the drainage

  3. Reliability analysis of idealized tunnel support system using probability-based methods with case studies

    Science.gov (United States)

    Gharouni-Nik, Morteza; Naeimi, Meysam; Ahadi, Sodayf; Alimoradi, Zahra

    2014-06-01

    In order to determine the overall safety of a tunnel support lining, a reliability-based approach is presented in this paper. Support elements in jointed rock tunnels are provided to control the ground movement caused by stress redistribution during the tunnel drive. Main support elements contribute to stability of the tunnel structure are recognized owing to identify various aspects of reliability and sustainability in the system. The selection of efficient support methods for rock tunneling is a key factor in order to reduce the number of problems during construction and maintain the project cost and time within the limited budget and planned schedule. This paper introduces a smart approach by which decision-makers will be able to find the overall reliability of tunnel support system before selecting the final scheme of the lining system. Due to this research focus, engineering reliability which is a branch of statistics and probability is being appropriately applied to the field and much effort has been made to use it in tunneling while investigating the reliability of the lining support system for the tunnel structure. Therefore, reliability analysis for evaluating the tunnel support performance is the main idea used in this research. Decomposition approaches are used for producing system block diagram and determining the failure probability of the whole system. Effectiveness of the proposed reliability model of tunnel lining together with the recommended approaches is examined using several case studies and the final value of reliability obtained for different designing scenarios. Considering the idea of linear correlation between safety factors and reliability parameters, the values of isolated reliabilities determined for different structural components of tunnel support system. In order to determine individual safety factors, finite element modeling is employed for different structural subsystems and the results of numerical analyses are obtained in

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

    Science.gov (United States)

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

    1974-01-01

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

  5. Case Study of Oriental Medicine Treatment with acupotomy Therpy of the Tarsal tunnel Syndrome

    Directory of Open Access Journals (Sweden)

    Lim Na-ra

    2009-03-01

    Full Text Available Purpose : In order to estimate clinical effects of Oriental Medicine Treatment with acupotomy therapy of Tarsal tunnel Syndrome Methods : From 5th November, 2008 to 8th November, 2008, 1 male patient diagnosed as Tarsal tunnel syndrome(clinical diagnosed was treated with general oriental medicine therapy (acupuncture, moxibustion, cupping, physical therapy, herbal medication and acupotomy. Results : The patient's Rt foot paresthesia, pain were remarkably improved. Conclusions : This study demonstrates that oriental medical treatment with acuputomy therapy has notable effect in improving symptoms of tarsal tunnel syndrome. as though we had not wide experience in this treatment, more research is needed.

  6. Single molecule manipulation at low temperature and laser scanning tunnelling photo-induced processes analysis through time-resolved studies

    International Nuclear Information System (INIS)

    Riedel, Damien

    2010-01-01

    This paper describes, firstly, the statistical analysis used to determine the processes that occur during the manipulation of a single molecule through electronically induced excitations with a low temperature (5 K) scanning tunnelling microscope (STM). Various molecular operation examples are described and the ability to probe the ensuing molecular manipulation dynamics is discussed within the excitation context. It is, in particular, shown that such studies can reveal reversible manipulation for tuning dynamics through variation of the excitation energy. Secondly, the photo-induced process arising from the irradiation of the STM junction is also studied through feedback loop dynamics analysis, allowing us to distinguish between photo-thermally and photo-electronically induced signals.

  7. Single molecule manipulation at low temperature and laser scanning tunnelling photo-induced processes analysis through time-resolved studies.

    Science.gov (United States)

    Riedel, Damien

    2010-07-07

    This paper describes, firstly, the statistical analysis used to determine the processes that occur during the manipulation of a single molecule through electronically induced excitations with a low temperature (5 K) scanning tunnelling microscope (STM). Various molecular operation examples are described and the ability to probe the ensuing molecular manipulation dynamics is discussed within the excitation context. It is, in particular, shown that such studies can reveal reversible manipulation for tuning dynamics through variation of the excitation energy. Secondly, the photo-induced process arising from the irradiation of the STM junction is also studied through feedback loop dynamics analysis, allowing us to distinguish between photo-thermally and photo-electronically induced signals. © 2010 IOP Publishing Ltd

  8. Scanning tunneling microscopy studies of glucose oxidase on gold surface

    International Nuclear Information System (INIS)

    Losic, D.; Shapter, J.G.; Gooding, J.J.

    2002-01-01

    Full text: Three immobilization methods have been used for scanning tunneling microscopy (STM) studies of glucose oxidase (GOD) on gold. They are based on a) physical adsorption from solution, b) microcontact printing and c) covalent bonding onto self-assembled monolayers (SAM) of 3-mercaptopropionic acid (MPA). The STM images are used to provide information about the organization of individual GOD molecules and more densely packed monolayers of GOD on electrode surfaces, thus providing information of the role of interfacial structure on biosensor performance. The use of atomically flat gold substrates enables easy distinction of deposited enzyme features from the flat gold substrate. Microcontact printing is found to be a more reliable method than adsorption from solution for preparing individual GOD molecules on the gold surface STM images of printed samples reveal two different shapes of native GOD molecules. One is a butterfly shape with dimensions of 10 ± 1 nm x 6 ± 1 nm, assigned to the lying position of molecule while the second is an approximately spherical shape with dimensions of 6.5 ± 1 nm x 5 ± 1nm assigned to a standing position. Isolated clusters of 5 to 6 GOD molecules are also observed. With monolayer coverage, GOD molecules exhibit a tendency to organize themselves into a two dimensional array with adequate sample stability to obtain high-resolution STM images. Within these two-dimensional arrays are clearly seen repeating clusters of five to six enzyme molecules in a unit STM imaging of GOD monolayers covalently immobilized onto SAM (MPA) are considerably more difficult than when the enzyme is adsorbed directly onto the metal. Cluster structures are observed both high and low coverage despite the fact that native GOD is a negatively charged molecule. Copyright (2002) Australian Society for Electron Microscopy Inc

  9. A Study of Vertical Transport through Graphene toward Control of Quantum Tunneling.

    Science.gov (United States)

    Zhu, Xiaodan; Lei, Sidong; Tsai, Shin-Hung; Zhang, Xiang; Liu, Jun; Yin, Gen; Tang, Min; Torres, Carlos M; Navabi, Aryan; Jin, Zehua; Tsai, Shiao-Po; Qasem, Hussam; Wang, Yong; Vajtai, Robert; Lake, Roger K; Ajayan, Pulickel M; Wang, Kang L

    2018-02-14

    Vertical integration of van der Waals (vdW) materials with atomic precision is an intriguing possibility brought forward by these two-dimensional (2D) materials. Essential to the design and analysis of these structures is a fundamental understanding of the vertical transport of charge carriers into and across vdW materials, yet little has been done in this area. In this report, we explore the important roles of single layer graphene in the vertical tunneling process as a tunneling barrier. Although a semimetal in the lateral lattice plane, graphene together with the vdW gap act as a tunneling barrier that is nearly transparent to the vertically tunneling electrons due to its atomic thickness and the transverse momenta mismatch between the injected electrons and the graphene band structure. This is accentuated using electron tunneling spectroscopy (ETS) showing a lack of features corresponding to the Dirac cone band structure. Meanwhile, the graphene acts as a lateral conductor through which the potential and charge distribution across the tunneling barrier can be tuned. These unique properties make graphene an excellent 2D atomic grid, transparent to charge carriers, and yet can control the carrier flux via the electrical potential. A new model on the quantum capacitance's effect on vertical tunneling is developed to further elucidate the role of graphene in modulating the tunneling process. This work may serve as a general guideline for the design and analysis of vdW vertical tunneling devices and heterostructures, as well as the study of electron/spin injection through and into vdW materials.

  10. Analytical study of the effects of wind tunnel turbulence on turbofan rotor noise

    Science.gov (United States)

    Gliebe, P. R.

    1980-01-01

    An analytical study of the effects of wind tunnel turbulence on turbofan rotor noise was carried out to evaluate the effectiveness of the NASA Ames 40 by 80-foot wind tunnel in simulating flight levels of fan noise. A previously developed theory for predicting rotor/turbulence interaction noise, refined and extended to include first-order effects of inlet turbulence anisotropy, was employed to carry out a parametric study of the effects of fan size, blade number, and operating line for outdoor test stand, NASA Ames wind tunnel, and flight inlet turbulence conditions. A major result of this study is that although wind tunnel rotor/turbulence noise levels are not as low as flight levels, they are substantially lower than the outdoor test stand levels and do not mask other sources of fan noise.

  11. Probing electronic interactions using electron tunneling

    Indian Academy of Sciences (India)

    pratap

    The scanning tunneling microscope: Principle d. eI. Tunneling Current. Topography by tracking current: Constant height mode. Tracking the height: Constant current mode. NbSe. 2 single crystal. (Grown by P. Shirage and A. Thamizhavel) ...

  12. X-ray absorption spectroscopy studies on magnetic tunnel junctions with AlO and AlN tunnel barriers

    International Nuclear Information System (INIS)

    Mun, B. S.; Moon, J. C.; Hong, S. W.; Kang, K. S.; Kim, K.; Kim, T. W.; Ju, H. L.

    2006-01-01

    X-ray photoelectron spectroscopy (XPS) and x-ray absorption spectroscopy (XAS) measurements of the optimized magnetic tunnel junctions (MTJs) with AlO and AlN barriers have been performed to study the chemical structures of the barrier and the underlying layer. These MTJs with AlO and AlN barriers exhibited increased tunneling magnetoresistance (TMR) after annealing at 200 deg. C from 27% to 45% and from 25% to 33%, respectively. Surprisingly, the XPS and XAS measurements confirmed that both the as-grown and the annealed MTJs had metallic Co and Fe at the interface between the barrier and the underlying CoFe layer. After annealing, under-stoichiometric AlO x and AlN x phases in MTJs with AlO and AlN barriers partially transformed into stoichiometric Al 2 O 3 and AlN phases, respectively. Thus the increase in TMR after annealing for MTJs with clean interface between the barrier and the underlying layer is believed due to the anion redistribution inside the barrier layer, not from back diffusion from pinned magnetic layer to barrier layer

  13. Nanomaterial engineering and property studies in a transmission electron microscope.

    Science.gov (United States)

    Golberg, Dmitri; Costa, Pedro M F J; Wang, Ming-Sheng; Wei, Xianlong; Tang, Dai-Ming; Xu, Zhi; Huang, Yang; Gautam, Ujjal K; Liu, Baodan; Zeng, Haibo; Kawamoto, Naoyki; Zhi, Chunyi; Mitome, Masanori; Bando, Yoshio

    2012-01-10

    Modern methods of in situ transmission electron microscopy (TEM) allow one to not only manipulate with a nanoscale object at the nanometer-range precision but also to get deep insights into its physical and chemical statuses. Dedicated TEM holders combining the capabilities of a conventional high-resolution TEM instrument and atomic force -, and/or scanning tunneling microscopy probes become the powerful tools in nanomaterials analysis. This progress report highlights the past, present and future of these exciting methods based on the extensive authors endeavors over the last five years. The objects of interest are diverse. They include carbon, boron nitride and other inorganic one- and two-dimensional nanoscale materials, e.g., nanotubes, nanowires and nanosheets. The key point of all experiments discussed is that the mechanical and electrical transport data are acquired on an individual nanostructure level under ultimately high spatial, temporal and energy resolution achievable in TEM, and thus can directly be linked to morphological, structural and chemical peculiarities of a given nanomaterial. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  14. Analytical study of the effects of wind tunnel turbulence on turbofan rotor noise. [NASA Ames 40 by 80 foot wind tunnel

    Science.gov (United States)

    Gliebe, P. R.; Kerschen, E. J.

    1979-01-01

    The influence of tunnel turbulence on turbofan rotor noise was carried out to evaluate the effectiveness of the NASA Ames 40 by 80 foot tunnel in simulating flight levels of fan noise. A previously developed theory for predicting rotor/turbulence interaction noise was refined and extended to include first-order effects of inlet turbulence anisotropy. This theory was then verified by carrying out extensive data/theory comparisons. The resulting model computer program was then employed to carry out a parametric study of the effects of fan size, blade number, and operating line on rotor/turbulence noise for outdoor test stand. NASA Ames wind tunnel, and flight inlet turbulence conditions. A major result of this study is that although wind tunnel rotor/turbulence noise levels are not as low as flight levels they are substantially lower than the outdoor test stand levels and do not mask other sources of fan noise.

  15. Electron microscopic study on SrGdMnO4

    International Nuclear Information System (INIS)

    Nakano, Hiromi; Ishizawa, Nobuo; Kamegashira, Naoki; Zulhadjri; Shishido, Toetsu

    2006-01-01

    Single crystals of SrGdMnO 4 have been synthesized by the floating zone method. The structure was characterized as the K 2 NiF 4 -type, using X-ray diffraction (XRD) and a transmission electron microscope (TEM). Presence of weak reflections breaking the archetypal tetragonal symmetry was observed from the selected area diffraction (SAD). The compound was found to have an orthorhombic unit cell of a ≅ b = 0.532(4) nm, c = 1.271(6) nm, by taking the a and b axes along the diagonal directions on the basal plane of the tetragonal archetype. Structural change occurred around 1018 K. The weak reflections disappeared in the SAD pattern, suggesting that crystal is of the archetype above 1018 K

  16. Theoretical study of phosphorene tunneling field effect transistors

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Jiwon; Hobbs, Chris [SEMATECH, 257 Fuller Rd #2200, Albany, New York 12203 (United States)

    2015-02-23

    In this work, device performances of tunneling field effect transistors (TFETs) based on phosphorene are explored via self-consistent atomistic quantum transport simulations. Phosphorene is an ultra-thin two-dimensional (2-D) material with a direct band gap suitable for TFETs applications. Our simulation shows that phosphorene TFETs exhibit subthreshold slope below 60 mV/dec and a wide range of on-current depending on the transport direction due to highly anisotropic band structures of phosphorene. By benchmarking with monolayer MoTe{sub 2} TFETs, we predict that phosphorene TFETs oriented in the small effective mass direction can yield much larger on-current at the same on-current/off-current ratio than monolayer MoTe{sub 2} TFETs. It is also observed that a gate underlap structure is required for scaling down phosphorene TFETs in the small effective mass direction to suppress the source-to-drain direct tunneling leakage current.

  17. Electroluminescence from single nanowires by tunnel injection: an experimental study

    OpenAIRE

    Zimmler, Mariano A.; Bao, Jiming; Shalish, Ilan; Yi, Wei; Yoon, Joonah; Narayanamurti, Venkatesh; Capasso, Federico

    2007-01-01

    We present a hybrid light-emitting diode structure composed of an n-type gallium nitride nanowire on a p-type silicon substrate in which current is injected along the length of the nanowire. The device emits ultraviolet light under both bias polarities. Tunnel-injection of holes from the p-type substrate (under forward bias) and from the metal (under reverse bias) through thin native oxide barriers consistently explains the observed electroluminescence behaviour. This work shows that the stan...

  18. First Principles Study of Electron Tunneling through Ice

    KAUST Repository

    Cucinotta, Clotilde S.

    2012-10-25

    With the aim of understanding electrochemical scanning tunnel microscopy experiments in an aqueous environment, we investigate electron transport through ice in the coherent limit. This is done by using the nonequilibrium Greens functions method, implemented within density functional theory, in the self-interaction corrected local density approximation. In particular, we explore different ice structures and different Au electrode surface orientations. By comparing the decay coefficient for different thicknesses to the ice complex band structure, we find that the electron transport occurs via tunneling with almost one-dimensional character. The slow decay of the current with the ice thickness is largely due to the small effective mass of the conduction electrons. Furthermore, we find that the calculated tunneling decay coefficients at the Fermi energy are not sensitive to the structural details of the junctions and are at the upper end of the experimental range for liquid water. This suggests that linear response transport measurements are not capable of distinguishing between different ordered ice structures. However, we also demonstrate that a finite bias measurement may be capable of sorting polar from nonpolar interfaces due to the asymmetry of the current-voltage curves for polar interfaces. © 2012 American Chemical Society.

  19. In situ stresses in rock masses: methodology for its study in tunnel projects in Spain

    International Nuclear Information System (INIS)

    Madirolas Perez, G.; Perucho Martinez, A.

    2014-01-01

    In situ stress is one of the main factors to be taken into account in the design of tunnels, as it can cause inadmissible stresses and strains leading to high deviations in the budgets. For that reason, the stress state is directly introduced into the numerical models used for the design of tunnels. In Spain, although several tunnels have been carried out with an important overburden in tectonically relevant zones, a quantitative determination of the stresses has not been usually included in civil work projects. Therefore, it is considered necessary to implement a routine procedure of study of civil work projects involving tunnels excavated in rock, and a new detailed methodology is proposed. The challenge is that project managers, who face works in which stresses may play a determinant role, may have a practical reference enabling them to optimize available resources and to include the real stress information in the design of underground works. (Author)

  20. Electron microscopical studies of the common bile duct in reindeer

    Directory of Open Access Journals (Sweden)

    Timo Rahko

    1990-08-01

    Full Text Available In a previous publication the authors have described some ultrastructural characteristics of granulated cells in the common bile duct of the reindeer. On the basis of the same material, electron microscopic observations on other tissue elements of bile duct wall are now reported. The surface and glandular epithelium were composed of tall columnar epithelial cells with villous structures on the luminal surfaces. The parietal cytoplasmic membranes of epithelial cells were equipped with intercellular desmosomes while intraepithelial globule leucocytes did not form any junctional complex with other cells. Apical cytoplasmic areas of superficial epithelial cells showed electron-dense small bodies possibly consisting of mucinous substances. The goblet and deep glandular cells, on the other hand, contained numerous large mucin granules with less electron-dense matrices. It appears that their secretions are more abundant than those in superficial epithelial cells which obviously are absorptive as their main function. The nuclei and other cytoplasmic organelles showed profiles similar to those in epithelial cells generally. The lumen of the bile ducts was usually empty or contained fine-granular or amorphous material. An unusual feature was the presence of parts of globule leucocytes or even almost whole cells occurring freely in ductal secretions.Elektronimikroskooppinen tutkimus yhteisen sappikäytävän rakenteesta porolla.Abstract in Finnish / Yhteenveto: Aikaisemmassa julkaisussa tekijät kuvasivat poron yhteisen sappikäytävän (ductus hepaticus communis seinämän jyväsellisten solujen hienorakennetta. Tässä artikkelissa selostetaan saman aineiston perusteella (6 tervettä teurasporoa elektronimikroskooppisia havaintoja sappikäytäväseinämän muista kudosrakenteista. Sappikäytäväseinämän pinta- ja rauhasepiteeli koostuu korkeista epiteelisoluista. Pinnallisia epiteelisoluja kattavat säännölliset mikrovillukset, ja niillä on vain v

  1. Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet with Shock Interactions

    Science.gov (United States)

    Cliff, Susan E.; Denison, Marie; Sozer, Emre; Moini-Yekta, Shayan

    2016-01-01

    NASA and Industry are performing vehicle studies of configurations with low sonic boom pressure signatures. The computational analyses of modern configuration designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty in the aft signatures with often greater boundary layer effects and nozzle jet pressures. Wind tunnel testing at significantly lower Reynolds numbers than in flight and without inlet and nozzle jet pressures make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel from Mach 1.6 to 2.0 will be used to assess the effects of shocks from components passing through nozzle jet plumes on the sonic boom pressure signature and provide datasets for comparison with CFD codes. A large number of high-fidelity numerical simulations of wind tunnel test models with a variety of shock generators that simulate horizontal tails and aft decks have been studied to provide suitable models for sonic boom pressure measurements using a minimally intrusive pressure rail in the wind tunnel. The computational results are presented and the evolution of candidate wind tunnel models is summarized and discussed in this paper.

  2. Apoptosis study of the macrophage via near-field scanning optical microscope

    International Nuclear Information System (INIS)

    Wang, D-C; Chen, K-Y; Chen, G-Y; Chen, S-H; Wun, S-J

    2008-01-01

    The cell apoptosis phenomenon was studied by traditional optical microscope with much lower resolution and also observed by Atomic Force Microscope (AFM) with nano-resolution recently. They both detect the cell apoptosis through the change of cell topography. In this study, the cell apoptosis was investigated via Near-Field Scanning Optical Microscope (NSOM). The cell topography, with nano-scaled resolution, and its optical characteristics were observed by NSOM at the same measurement scanning. The macrophage was chosen as the cell investigated. To understand the cell apoptosis process is the goal set for the research. The apoptosis process was related to the variations of the optical characteristics of the cell

  3. Microscopic models for the study of taxpayer audit effects

    Science.gov (United States)

    Bertotti, Maria Letizia; Modanese, Giovanni

    2016-03-01

    A microscopic dynamic model is here constructed and analyzed, describing the evolution of the income distribution in the presence of taxation and redistribution in a society in which also tax evasion and auditing processes occur. The focus is on effects of enforcement regimes, characterized by different choices of the audited taxpayer fraction and of the penalties imposed to noncompliant individuals. A complex systems perspective is adopted: society is considered as a system composed by a large number of heterogeneous individuals. These are divided into income classes and may as well have different tax evasion behaviors. The variation in time of the number of individuals in each class is described by a system of nonlinear differential equations of the kinetic discretized Boltzmann type involving transition probabilities. A priori, one could think that audits and fines should have a positive effect on the reduction of economic inequality and correspondingly of the Gini index G. According to our model, however, such effect is rather small. In contrast, the effect on the increase of the tax revenue may be significant.

  4. Microscopic study reveals the singular origins of growth

    Science.gov (United States)

    Yaari, G.; Nowak, A.; Rakocy, K.; Solomon, S.

    2008-04-01

    Anderson [Science 177, 293 (1972)] proposed the concept of complexity in order to describe the emergence and growth of macroscopic collective patterns out of the simple interactions of many microscopic agents. In the physical sciences this paradigm was implemented systematically and confirmed repeatedly by successful confrontation with reality. In the social sciences however, the possibilities to stage experiments to validate it are limited. During the 90's a series of dramatic political and economic events have provided the opportunity to do so. We exploit the resulting empirical evidence to validate a simple agent based alternative to the classical logistic dynamics. The post-liberalization empirical data from Poland confirm the theoretical prediction that the dynamics is dominated by singular rare events which insure the resilience and adaptability of the system. We have shown that growth is led by few singular “growth centers" (Fig. 1), that initially developed at a tremendous rate (Fig. 3), followed by a diffusion process to the rest of the country and leading to a positive growth rate uniform across the counties. In addition to the interdisciplinary unifying potential of our generic formal approach, the present work reveals the strong causal ties between the “softer" social conditions and their “hard" economic consequences.

  5. Scanning tunneling spectroscopy on electron-boson interactions in superconductors

    CERN Document Server

    Schackert, Michael Peter

    2015-01-01

    This work describes the experimental study of electron-boson interactions in superconductors by means of inelastic electron tunneling spectroscopy performed with a scanning tunneling microscope (STM) at temperatures below 1 K. This new approach allows the direct measurement of the Eliashberg function of conventional superconductors as demonstrated on lead (Pb) and niobium (Nb). Preparative experiments on unconventional iron-pnictides are presented in the end.

  6. Electroluminescence from single nanowires by tunnel injection: an experimental study

    Science.gov (United States)

    Zimmler, Mariano A.; Bao, Jiming; Shalish, Ilan; Yi, Wei; Yoon, Joonah; Narayanamurti, Venkatesh; Capasso, Federico

    2007-06-01

    We present a hybrid light-emitting diode structure composed of an n-type gallium nitride nanowire on a p-type silicon substrate in which current is injected along the length of the nanowire. The device emits ultraviolet light under both bias polarities. Tunnel injection of holes from the p-type substrate (under forward bias) and from the metal (under reverse bias) through thin native oxide barriers consistently explains the observed electroluminescence behaviour. This work shows that the standard p-n junction model is generally not applicable to this kind of device structure.

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

    Science.gov (United States)

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

    2010-01-01

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

  8. Study and fabrication of tunnel diodes made on germanium using a collective planar technique

    International Nuclear Information System (INIS)

    Vrahides, Michel

    1973-01-01

    The main results of the theory on tunnel diodes are presented in the first chapter. From these results are deduced the technological requirements that any fabrication process should meet to make tunnel diodes. These requirements show up that, among the three techniques for junction making (thermal diffusion of impurities, epitaxy, alloying), the last one is presently the best fitted to the fabrication of tunnel junctions. By analyzing the defects created by various alloying technologies presently used, together with a study of the benefits due to a use of chemical photolithography, evaporation under vacuum and masking by deposited oxide, it is possible to design a tentative scheme of a 0.5 ns tunnel diode. Then, in a second chapter, is presented the collective process for fabrication that has been used on monocrystalline, P-type, germanium wafers. 8 000 tunnel diodes may be positioned on a 1.5 inch diameter wafer by using that process. A description of the various apparatus used is also given. The experimental results are described in the third chapter. The influence of the various fabrication parameters on the electrical characteristics of the diodes are discussed. It is shown, by studying the fabrication yields and parameter spreading, that 80 per cent of the diodes exhibit a standard tunnel diode behaviour and that 90 per cent of these present a peak current dispersion less than ± 25 per cent. When measuring at the peak current drifts under temperature stresses, a good analogy with conventional tunnel diode is found. Some measurements of switching times have led to values as low as 0.6 nanoseconds. (author) [fr

  9. PREFACE: Time-resolved scanning tunnelling microscopy Time-resolved scanning tunnelling microscopy

    Science.gov (United States)

    Zandvliet, Harold J. W.; Lin, Nian

    2010-07-01

    Scanning tunnelling microscopy has revolutionized our ability to image, manipulate, and investigate solid surfaces on the length scale of individual atoms and molecules. The strength of this technique lies in its imaging capabilities, since for many scientists 'seeing is believing'. However, scanning tunnelling microscopy also suffers from a severe limitation, namely its poor time resolution. Recording a scanning tunnelling microscopy image typically requires a few tens of seconds for a conventional scanning tunnelling microscope to a fraction of a second for a specially designed fast scanning tunnelling microscope. Designing and building such a fast scanning tunnelling microscope is a formidable task in itself and therefore, only a limited number of these microscopes have been built [1]. There is, however, another alternative route to significantly enhance the time resolution of a scanning tunnelling microscope. In this alternative method, the tunnelling current is measured as a function of time with the feedback loop switched off. The time resolution is determined by the bandwidth of the IV converter rather than the cut-off frequency of the feedback electronics. Such an approach requires a stable microscope and goes, of course, at the expense of spatial information. In this issue, we have collected a set of papers that gives an impression of the current status of this rapidly emerging field [2]. One of the very first attempts to extract information from tunnel current fluctuations was reported by Tringides' group in the mid-1990s [3]. They showed that the collective diffusion coefficient can be extracted from the autocorrelation of the time-dependent tunnelling current fluctuations produced by atom motion in and out of the tunnelling junction. In general, current-time traces provide direct information on switching/conformation rates and distributions of residence times. In the case where these processes are thermally induced it is rather straightforward to map

  10. Molecules on vicinal Au surfaces studied by scanning tunnelling microscopy

    International Nuclear Information System (INIS)

    Kroeger, J; Neel, N; Jensen, H; Berndt, R; Rurali, R; Lorente, N

    2006-01-01

    Using low-temperature scanning tunnelling microscopy and spectroscopy we investigated the adsorption characteristics of 3,4,9,10-perylenetetracarboxylic-dianhydride and fullerenes on Au(788), Au(433), and Au(778). On Au(788) and Au(778), 3,4,9,10-perylenetetracarboxylic-dianhydride exhibits three coexisting superstructures, which do not reflect the periodicity of the hosting substrate. The adsorption on Au(433) leads to the formation of molecule chains along the step edges after annealing the sample. Fullerene molecules on Au(788) arrange in a mesh of islands, which extends over several hundreds of nanometres with an extraordinarily high periodicity. A combination of fullerene adsorption and annealing leads to facetting of Au(433) and the formation of extraordinarily long fullerene stripes

  11. Potential risks at an industrial site: A wind tunnel study

    Czech Academy of Sciences Publication Activity Database

    Jaňour, Zbyněk; Jurčáková, Klára; Brych, Karel; Dittrt, František; Dittrich, F.

    2010-01-01

    Roč. 88, č. 3 (2010), s. 185-190 ISSN 0957-5820 R&D Projects: GA MŠk(CZ) OC 113 Institutional research plan: CEZ:AV0Z20760514; CEZ:AV0Z20600510 Keywords : atmospheric turbulence * flow visualization * wind tunnel modeling Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.453, year: 2010 http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B8JGG-4Y7P8YF-1&_user=640952&_coverDate=05%2F31%2F2010&_rdoc=1&_fmt=high&_orig=search&_sort=d&_docanchor=&view=c&_searchStrId=1433050901&_rerunOrigin= google &_acct=C000034318&_version=1&_urlVersion=0&_userid=640952&md5=b036d2c5d747eadc03ff5697ea45e6a2

  12. Posterior cruciate ligament reconstruction by means of tibial tunnel: anatomical study on cadavers for tunnel positioning

    Directory of Open Access Journals (Sweden)

    Antônio Altenor Bessa de Queiroz

    2014-08-01

    Full Text Available Objective:To determine the reference points for the exit of the tibial guidewire in relation to the posterior cortical bone of the tibia.Methods:Sixteen knees from fresh cadavers were used for this study. Using a viewing device and a guide marked out in millimeters, three guidewires were passed through the tibia at 0, 10 and 15 mm distally in relation to the posterior crest of the tibia. Dissections were performed and the region of the center of the tibial insertion of the posterior cruciate ligament (PCL was determined in each knee. The distances between the center of the tibial insertion of the PCL and the posterior tibial border (CB and between the center of the tibial insertion of the PCL and wires 1, 2 and 3 (CW1, CW2 and CW3 were measured.Results:In the dissected knees, we found the center of the tibial insertion of the PCL at 1.09 ± 0.06 cm from the posterior tibial border. The distances between the wires 1, 2 and 3 and the center of the tibial insertion of the PCL were respectively 1.01 ± 0.08, 0.09 ± 0.05 and 0.5 ± 0.05 cm.Conclusion:The guidewire exit point 10 mm distal in relation to the posterior crest of the tibia was the best position for attempting to reproduce the anatomical center of the PCL.

  13. Comparison of microscopic and endoscopic view of the internal acoustic meatus: A cadaveric study.

    Science.gov (United States)

    Montibeller, Guilherme Ramina; Hendrix, Philipp; Fries, Fabian N; Becker, Kurt W; Oertel, Joachim

    2018-04-01

    The endoscope is thought to provide an improved exposure of the internal acoustic meatus after retrosigmoid craniotomy for microsurgical resection of intrameatal tumors. The aim of this study is to quantify the differences in internal acoustic meatus (IAM) exposure comparing microscopic and endoscopic visualization. A retrosigmoid approach was performed on 5 cadaver heads. A millimeter gauge was introduced into the internal acoustic meatus, and examinations with a surgical microscope and 0°, 30° and 70° rigid endoscopes were performed. The extent of IAM depth visualized with the microscope and the different angled endoscopes were analyzed. The microscopic view allowed an average IAM depth visualization of 2.8 mm. The endoscope allowed an improved exposure of IAM in all cases. The 0°, 30° and 70° endoscopes permitted an exposure that was respectively 96% (5.5 mm), 139% (6.7 mm) and 200% (8.4 mm) more lateral than the microscopic view. Angled optics, however, provided an image distortion, specifically the 70° endoscope. The endoscope provides a superior visualization of the IAM compared to the microscope when using a retrosigmoid approach. The 30° endoscope represented an ideal compromise of superior visualization with marginal image distortion. Additional implementation of the endoscope into microsurgery of intrameatal tumors likely facilitates complete tumor removal and might spare facial and vestibulocochlear function. Clin. Anat. 31:398-403, 2018. © 2017 Wiley Periodicals, Inc. © 2017 Wiley Periodicals, Inc.

  14. Thermovoltages in vacuum tunneling investigated by scanning tunneling microscopy

    OpenAIRE

    Hoffmann, D. H.; Rettenberger, Armin; Grand, Jean Yves; Läuger, K.; Leiderer, Paul; Dransfeld, Klaus; Möller, Rolf

    1995-01-01

    By heating the tunneling tip of a scanning tunneling microscope the thermoelectric properties of a variable vacuum barrier have been investigated. The lateral variation of the observed thermovoltage will be discussed for polycrystalline gold, stepped surfaces of silver, as well as for copper islands on silver.

  15. Tetrairon(III) Single Molecule Magnet Studied by Scanning Tunneling Microscopy and Spectroscopy

    Science.gov (United States)

    Oh, Youngtek; Jeong, Hogyun; Lee, Minjun; Kwon, Jeonghoon; Yu, Jaejun; Mamun, Shariful Islam; Gupta, Gajendra; Kim, Jinkwon; Kuk, Young

    2011-03-01

    Tetrairon(III) single-molecule magnet (SMM) on a clean Au(111) has studied using scanning tunneling microscopy (STM) and spectroscopy (STS) to understand quantum mechanical tunneling of magnetization and hysteresis of pure molecular origin. Before the STM studies, elemental analysis, proton nuclear magnetic resonance (NMR) measurement and Energy Dispersive X- ray Spectroscopy (EDS) were carried out to check the robustness of the sample. The STM image of this molecule shows a hexagonal shape, with a phenyl ring at the center and surrounding six dipivaloylmethane ligands. Two peaks are observed at 0.5 eV, 1.5 eV in the STS results, agreeing well with the first principles calculations. Spin-polarized scanning tunneling microscopy (SPSTM) measurements have been performed with a magnetic tip to get the magnetization image of the SMM. We could observe the antiferromagnetic coupling and a centered- triangular topology with six alkoxo bridges inside the molecule while applying external magnetic fields.

  16. Experimental study of wind tunnel performance by a two-component laserDopplerAnemometer

    Directory of Open Access Journals (Sweden)

    M Pourmahabadian

    2005-10-01

    Full Text Available Background and Aims: This survey studies the wind tunnel performance by a two- componentlaser Doppler Anemometer, so some experiments were carried out to assess the performance of awind tunnel.Method: The tunnel was capable to produce air velocity of up to 40 m/s.. Measurements ofvelocity profiles have been made actors the test section of wind tunnel through the using a twocomponentfiber optic Laser Doppler anemometer. Measurements of velocity profiles andturbulence intensities have been made across the test section of the wind tunnel using a twocomponentfiber optic Laser Doppler anemometer (I.D.A for wind speeds ranging from 1 to3m/s.Results: Performance rests of velocity profiles at a given flow rate and various position of aerosolgenerator showed that although uniformity of flow dependent to the place of an atomizer (asaerosol generator but the variation of wind speed across the test section meets the wind speedrequirements, as specified by US EPAfor 3m/s only.Conclusion:At time which particles velocity reach to less than one micron, the air velocity relateson the similarity of particles and

  17. A scanning electron microscopic study of biliary stent materials

    NARCIS (Netherlands)

    van Berkel, A. M.; van Marle, J.; van Veen, H.; Groen, A. K.; Huibregtse, K.

    2000-01-01

    Clogging of biliary stents remains an important problem. In vitro studies have shown less sludge formation in Teflon stents. Recently, clinical studies with Teflon stents have produced contradictory results. The aim of this study was to investigate whether the surface properties of the

  18. Histological and electron microscopic study of the postulated ...

    African Journals Online (AJOL)

    Di(2-ethylhexyl)phthalate [DEHP] is a plasticizer (softener) used to increase the flexibility of polyvinyl chloride (plastic). Animal studies following acute and chronic exposure of DEHP show several toxic changes in many organs including the liver. There have been no studies of compound specific techniques for reducing ...

  19. Study of the tunneling effect within lattices with cubic structure on varying temperature

    International Nuclear Information System (INIS)

    Frisone, F.

    2008-01-01

    In this theoretical study, it is underlined that the presence of micro-cracks in the lattice structure increases the probability of tunneling effect between two deuterons by some orders of magnitude with respect to non-deformed lattices. We have derived an expression to compute the tunneling probability within a micro-crack, and hypothesized a D + 2 -D + 2 binding mechanism. Finally, the overall indications provided by these theoretical simulations appear to suggest that the deformation of the crystalline lattice, at varying temperature, seems able to influence the process of tunneling between the deuterons in the metal, while the forced loading with D 2 has, in general, no evident positive effects in pure metals, but in some cases could, on the contrary, condition the phenomenon negatively. (authors)

  20. Study and evaluation of ferro-cement for use in wind tunnel construction

    Science.gov (United States)

    Larsen, H. J., Jr. (Compiler)

    1972-01-01

    The structural suitability and cost effectiveness of ferro-cement for large subsonic wind tunnel structures is investigated. This investigation was carried out in the following four main categories: (1) a state-of-the-art survey into the uses, properties, and costs of ferro-cement; (2) an evaluation of those ferro-cement properties critical to construction of large, subsonic wind tunnels, which have not been adequately established to date; (3) a laboratory testing program to determine preliminary values for those properties; and (4) a study to establish cost factors for ferro-cement as related to a preliminary construction scheme for a nacelle and shroud unit.

  1. Bipolar budding in yeasts - an electron microscope study

    NARCIS (Netherlands)

    Kreger-van Rij, N.J.W.; Veenhuis, M.

    1971-01-01

    Bud formation in yeasts with bipolar budding was studied by electron microscopy of thin sections. Budding in yeasts of the species Saccharomycodes ludwigii, Hanseniaspora valbyensis and Wickerhamia fluorescens resulted in concentric rings of scar ridges on the wall of the mother cell. The wall

  2. Ant-egg cataract. An electron microscopic study

    DEFF Research Database (Denmark)

    Schrøder, H D; Nissen, S H

    1979-01-01

    The ultrastructure of the ant-egg cataractous lens has been studied. Comparison of tissue demineralized by means of EDTA with untreated tissue showed the calcium salts in the ant-eggs to be mostly crystalline. A laminar appearance of the ant-egg seen in EDTA treated material suggested an intermit...

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

    Science.gov (United States)

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

    1991-01-01

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

  4. Microscopic properties of MPCVD diamond coatings studied by ...

    Indian Academy of Sciences (India)

    the reactant gas (CH4– H2) flow rate with these defects. For high flow rates of CH4– H2, the defect density in W3 grains, as seen in figure 8b is less than that for the diamond grains of. W1 shown in figure 8a. These results are in good agreement with the Raman and PL studies. This might be due to the fast gas exchange that ...

  5. An experimental study of the exergetic performance of an underground air tunnel system for greenhouse cooling

    International Nuclear Information System (INIS)

    Ozgener, Leyla; Ozgener, Onder

    2010-01-01

    The present study highlights the exergetic performance characteristics of an underground air tunnel for greenhouse cooling with a 47 m horizontal, 56 cm nominal diameter U-bend buried galvanized ground heat exchanger. This system was designed and installed in the Solar Energy Institute, Ege University, Izmir, Turkey. Underground air tunnel systems, also known as earth-to-air heat exchangers, are recognized to be outstanding heating, cooling and air heating systems. On the other hand, they have not been used yet in the Turkish market. Greenhouses also have important economical potential in Turkey's agricultural sector. Greenhouses should be cooled during the summer or hot days. In order to establish optimum growth conditions in greenhouses, renewable energy sources should be utilized as much as possible. It is expected that effective use of underground air tunnels with a suitable technology in the modern greenhouses will play a leading role in Turkey in the foreseeable future. The exergy transports between the components and the destructions in each of the components of the system are determined for the average measured parameters obtained from the experimental results. Exergetic efficiencies of the system components are determined in an attempt to assess their individual performances and the potential for improvements is also presented. The daily maximum cooling coefficient of performances (COP) values for the system are also obtained to be 15.8. The total average COP in the experimental period is found to be 10.09. The system COP was calculated based on the amount of cooling produced by the air tunnel and the amount of power required to move the air through the tunnel, while the exergetic efficiency of the air tunnel is found to be in a range among 57.8-63.2%. The overall exergy efficiency value for the system on a product/fuel basis is found to be 60.7%. (author)

  6. Study and microscopic characterization of the cadmium telluride deep levels

    International Nuclear Information System (INIS)

    Biglari, B.

    1989-05-01

    The spectroscopic methods PICTS, QTS and CTS were developed and perfected to investigate deep level analysis of high resistivity CdTe crystals which were either undoped, or doped with chlorine and copper. Crystals which were grown in space were also investigated. The main characterization of defect levels was determined and different correlations were established between the material's resistivity, chemical residues, dopant concentration and the nuclear radiation detector parameters. Using PICTS and CTS techniques, the generation of defects, under strong gamma-ray irradiation and particle bombardment was also studied. The influence of hydrogen on the main electrical characteristics of CdTe, in particular its ability to passivate the electrical activity of many deep defect and impurity states have been demonstrated. The compensation effects of Cl, Cu and H + are interpreted using the qualitative models based on different possibilities of pairing or triplet formation between the ions of these dopants and those of defects [fr

  7. Microscopical Studies of Structural and Electronic Properties of Semiconductors

    CERN Multimedia

    2002-01-01

    The electronic and structural properties of point defects in semiconductors, e.g. radiation defects, impurities or passivating defects can excellently be studied by the hyperfine technique of Perturbed Angular Correlation (PAC). The serious limitation of this method, the small number of chemically different radioactive PAC probe atoms can be widely overcome by means of ISOLDE. Providing shortliving isotopes, which represent common dopants as well as suitable PAC probe atoms, the ISOLDE facility enables a much broader application of PAC to problems in semiconductor physics.\\\\ Using the probe atom $^{111m}$ Cd , the whole class of III-V compounds becomes accessible for PAC investigations. First successful experiments in GaAs, InP and GaP have been performed, concerning impurity complex formation and plasma induced defects. In Si and Ge, the electronic properties~-~especially their influence on acceptor-donor interaction~-~could be exemplarily st...

  8. Quantum tunnelling in condensed media

    CERN Document Server

    Kagan, Yu

    1992-01-01

    The essays in this book deal with of the problem of quantum tunnelling and related behavior of a microscopic or macroscopic system, which interacts strongly with an ""environment"" - this being some form of condensed matter. The ""system"" in question need not be physically distinct from its environment, but could, for example, be one particular degree of freedom on which attention is focussed, as in the case of the Josephson junction studied in several of the papers. This general problem has been studied in many hundreds, if not thousands, of articles in the literature, in contexts as diverse

  9. Hair morphology in androgenetic alopecia: sonographic and electron microscopic studies.

    Science.gov (United States)

    Wortsman, Ximena; Guerrero, Robinson; Wortsman, Jacobo

    2014-07-01

    To assess hair morphology in androgenetic alopecia on sonography and electron microscopy. A prospective study was performed in 33 patients with androgenetic alopecia and 10 unaffected control participants. In vivo sonography of the hair follicles of the scalp and in vitro sonography and electron microscopy of the hair shafts were performed according to a standardized protocol that included analysis of the right frontal and occipital regions. The upper frequency limit of the ultrasound probes ranged between 15 and 18 MHz. Scalp hair follicles and hair shafts were recognizable on sonography in all cases. Hair follicles in alopecia cases had significantly lower depths (P alopecia also had a different distribution of their laminar pattern on in vitro sonography, with a greater presence of mixed (trilaminar and bilaminar) and solely bilaminar tracts in comparison with the controls (mostly trilaminar). On electron microscopy, the alopecia hair tracts showed irregularities and commonly a "melted candle" appearance of the cuticle. Sonography and electron microscopy uncover distinct abnormalities in the morphology of hair in androgenetic alopecia, which may potentially support the diagnosis and management of this common condition. © 2014 by the American Institute of Ultrasound in Medicine.

  10. Demodex mites in acne rosacea: reflectance confocal microscopic study.

    Science.gov (United States)

    Turgut Erdemir, Asli; Gurel, Mehmet Salih; Koku Aksu, Ayse Esra; Falay, Tugba; Inan Yuksel, Esma; Sarikaya, Ebru

    2017-05-01

    Demodex mite density is emphasised in the aetiopathogenesis of acne rosacea. Reflectance confocal microscopy (RCM) has been shown to be a good method for determining demodex mite density. The objective was to determine demodex mite density using RCM in acne rosacea patients and compare them with controls. In all, 30 papulopustular rosacea (PPR) and 30 erythematotelangiectatic rosacea (ETR) totally 60 acne rosacea patients and 40 controls, were enrolled in the study. The right cheek was selected for imaging and RCM was used for scanning. Ten images of 1000 × 1000 μm (total 10 mm 2 ) area were scanned from adjacent areas. The numbers of follicles, infested follicles and mites were counted. The mean numbers of mites per follicle and infested follicles were calculated and compared in the patients and control groups. The mean number of mites was 44.30 ± 23.22 in PPR, 14.57 ± 15.86 in ETR and 3.55 ± 6.48 in the control group (P rosacea aetiopathogenesis. Demodex mite treatment may reduce the severity of the disease and slow its progressive nature. © 2016 The Australasian College of Dermatologists.

  11. Scanning and transmission electron microscope study of pellicle morphogenesis.

    Science.gov (United States)

    Lie, T

    1977-05-01

    The morphology of pellicle formation was studied using correlated transmission and scanning electron microscopy. Pellicle developed on hydroxyapatite/epoxy resin splints attached to the buccal surfaces of molars and premolars in six young individuals. Splint segments were removed at intervals of 2, 4, 6, 12, 24, and 48 h. Measurements of pellicle thickness revealed that during the first 12 h considerably more material formed on the apatite surfaces than on the epoxy resin areas of the splints. This difference was equalized in 24- and 48-h specimens. Three types of pellicles could be distinguished on the basis of morphologic criteria. A globular pellicle, characterized by a consistent presence of globules of varying size and configuration, seemed to predominate in most subjects. These globules could not be mistaken for bacteria due to their dimensions, contour, and lack of cell walls. A fibrillar pellicle consisted of 3- to 7-nm-wide fibrils and frequently included some finely globular particles. A granular pellicle displayed a relatively even surface contour and did not exhibit globular or fibrillar structures. In contrast to the two other types, the granular pellicle contained distinct laminations. Apparently, the varying morphology of the early pellicle is a reflection of its complex chemical composition.

  12. Raman microscopic studies of PVD deposited hard ceramic coatings

    International Nuclear Information System (INIS)

    Constable, C.P.

    2000-01-01

    PVD hard ceramic coatings grown via the combined cathodic arc/unbalance magnetron deposition process were studied using Raman microscopy. Characteristic spectra from binary, multicomponent, multilayered and superlattice coatings were acquired to gain knowledge of the solid-state physics associated with Raman scattering from polycrystalline PVD coatings and to compile a comprehensive spectral database. Defect-induced first order scattering mechanisms were observed which gave rise to two pronounced groups of bands related to the acoustical (150- 300cm -1 ) and optical (400-7 50cm -1 ) parts of the phonon spectrum. Evidence was gathered to support the theory that the optic modes were mainly due to the vibrations of the lighter elements and the acoustic modes due to the vibrations of the heavier elements within the lattice. A study into the deformation and disordering on the Raman spectral bands of PVD coatings was performed. TiAIN and TiZrN coatings were intentionally damaged via scratching methods. These scratches were then analysed by Raman mapping, both across and along, and a detailed spectral interpretation performed. Band broadening occurred which was related to 'phonon relaxation mechanisms' as a direct result of the breaking up of coating grains resulting in a larger proportion of grain boundaries per-unit-volume. A direct correlation of the amount of damage with band width was observed. Band shifts were also found to occur which were due to the stresses caused by the scratching process. These shifts were found to be the largest at the edges of scratches. The Raman mapping of 'droplets', a defect inherent to PVD deposition processes, found that higher compressive stresses and large amounts of disorder occurred for coating growth onto droplets. Strategies designed to evaluate the ability of Raman microscopy to monitor the extent of real wear on cutting tools were evaluated. The removal of a coating layer and subsequent detection of a base layer proved

  13. Carpal tunnel sonography by the rheumatologist versus nerve conduction study by the neurologist

    NARCIS (Netherlands)

    Swen, WAA; Jacobs, JWG; Bussemaker, FEAM; de Waard, J; Bijlsma, JWJ

    Objective. To determine the value of sonogaphy (SG) performed by the rheumatologist to diagnose carpal tunnel syndrome (CTS). Methods. Sixty-three patients with clinical signs of CTS according to the neurologist. based on patient history and clinical examination, were studied. In the 6 weeks prior

  14. Fermilab digs 4,000-foot tunnel for neutrino study near Batavia

    CERN Multimedia

    Grady, W

    2002-01-01

    As part of a construction project that began more than two years ago, workers have carved out 4,000 feet of tunnel and two huge caverns under a portion of Fermilab's site near Batavia. The $171 million project will provide research facilities for an experiment designed to study neutrinos (1 page).

  15. The study of electrical conductivity of DNA molecules by scanning tunneling spectroscopy

    Science.gov (United States)

    Sharipov, T. I.; Bakhtizin, R. Z.

    2017-10-01

    An interest to the processes of charge transport in DNA molecules is very high, due to perspective of their using in nanoelectronics. The original sample preparation for studying electrical conductivity of DNA molecules by scanning tunneling spectroscopy has been proposed and tested. The DNA molecules immobilized on gold surface have been imaged clearly and their current-voltage curves have been measured.

  16. A field wind tunnel study of fine dust emissions in sandy soils

    Science.gov (United States)

    A portable field wind tunnel has been developed to allow measurements of dust emissions from soil surfaces to test the premise that dust concentration and properties are highly correlated with surface soil properties, as modified by crop management system. In this study, we report on the effect of ...

  17. Numerical Study of the High-Speed Leg of a Wind Tunnel

    Science.gov (United States)

    Nayani, Sudheer; Sellers, William L., III; Brynildsen, Scott E.; Everhart, Joel L.

    2015-01-01

    The paper describes the numerical study of the high-speed leg of the NASA Langley 14 by 22-foot Low Speed Wind Tunnel. The high-speed leg consists of the Settling Chamber, Contraction, Test Section, and First Diffuser. Results are shown comparing two different exit boundary conditions and two different methods of determining the surface geometry.

  18. Adsorption of Cu phthalocyanine on Pt modified Ge(001): A scanning tunneling microscopy study

    NARCIS (Netherlands)

    Saedi, A.; Berkelaar, Robin P.; Kumar, Avijit; Poelsema, Bene; Zandvliet, Henricus J.W.

    2010-01-01

    The adsorption configurations of copper phthalocyanine (CuPc) molecules on platinum-modified Ge(001) have been studied using scanning tunneling microscopy. After deposition at room temperature and cooling down to 77 K the CuPc molecules are still dynamic. However, after annealing at 550±50 K, the

  19. Airflow in the CNGS tunnel structures$bA study for ensured operational safety

    CERN Document Server

    Blom, R

    2003-01-01

    In the CNGS project, the nature of neutrinos is to be studied. These neutrinos are created by a radioactive decay, and to control the path of the particles that decay into neutrinos, a large under-pressure tunnel is needed. To have such a large evacuated volume, where the pressure is kept at 100 Pa, connected with areas accessible for the personnel, might be hazardous. The purpose of this study is to quantify, by means of CFD simulations, the airflow, air velocity, pressure and temperature that would arise in the tunnels in case of a rupture in the sealing of the evacuated tunnel. For the simulated case, where the titanium window that seals the tunnel disappears completely in an accident, the pressure drops to 0.987 bar in the area accessible to the personnel after 7 seconds. An airflow velocity of 50.9 meters per second accompanies this pressure drop. As possible means of personnel protection, the effects of using safety baffles have been studied. These measures would, with a 50 percent close off, lead to a ...

  20. Study of dust re-suspension at low pressure in a dedicated wind-tunnel

    Science.gov (United States)

    Rondeau, Anthony; Sabroux, Jean-Christophe; Chassefière, Eric

    2015-04-01

    The atmosphere of several telluric planets or satellites are dusty. Such is the case of Earth, Venus, Mars and Titan, each bearing different aeolian processes linked principally to the kinematic viscosity of the near-surface atmosphere. Studies of the Martian atmosphere are particularly relevant for the understanding of the dust re-suspension phenomena at low pressure (7 mbar). It turns out that operation of fusion reactors of the tokamak design produces significant amount of dust through the erosion of plasma-facing components. Such dust is a key issue, both regarding the performance and the safety of a fusion reactor such as ITER, under construction in Cadarache, France. Indeed, to evaluate the explosion risk in the ITER fusion reactor, it is essential to quantify the re-suspended dust fraction as a function of the dust inventory that can be potentially mobilized during a loss of vacuum accident (LOVA), with air or water vapour ingress. A complete accident sequence will encompass dust re-suspension from near-vacuum up to atmospheric pressure. Here, we present experimental results of particles re-suspension fractions measured at 1000, 600 and 300 mbar in the IRSN BISE (BlowIng facility for airborne releaSE) wind tunnel. Both dust monolayer deposits and multilayer deposits were investigated. In order to obtain experimental re-suspension data of dust monolayer deposits, we used an optical microscope allowing to measure the re-suspended particles fraction by size intervals of 1 µm. The deposits were made up of tungsten particles on a tungsten surface (an ubiquitous plasma facing component) and alumina particles on a glass plate, as a surrogate. A comparison of the results with the so-called Rock'nRoll dust re-suspension model (Reeks and Hall, 2001) is presented and discussed. The multilayer deposits were made in a vacuum sedimentation chamber allowing to obtain uniform deposits in terms of thickness. The re-suspension experimental data of such deposits were obtained

  1. Modernization of the REHMP-2 scanning electron microscope to study semiconductors

    International Nuclear Information System (INIS)

    Nazarkin, V.N.; Korob, E.B.

    1977-01-01

    The REMP-2 raster microscope has been modernized in order to adjust it for investigations of semiconductors by diode current signal (DCS) technique. The changes in the secondary electronic image circuit provided for its higher reliability. Presentation of DCS on the screen of the electron beam tube of the microscope display involved either modulations of the screen brightness or modulations of deviation on the screen and at the recorder. With the use of a recorder it was possible to study objects of an essentially greater area. A sensitive amplifier of DCS provides for working with weak signals and for quantitative investigations. Investigations of semiconductors at low temperatures is carried out with the help of an objective table cooled by liquid nitrogen. The illustrations show some capacities of the modernized REMP-2 microscope for DCS investigations of semiconductors

  2. [Study on microscopic identification of Astragalus complanatus and A. adsurgens seeds].

    Science.gov (United States)

    Li, Xiao-lin; Shao, Ai-juan; Zhan, Xiao-ri; Wei, Ying; Huang, Lu-qi

    2015-04-01

    Astragalus adsurgens seed is one of the most common adulterants of Astragali Complanati Semen in the market, whose morphological characteristics are very similar with A. complanatus seeds (Astragali Complanati Semen). Many identification methods have been reported, such as morphological identification, fluorescence method, ultraviolet spectrophotometry, TLC, HPLC, protein electrophoresis and so on, but there's no much about microscopic identification. In the present study, the morphological characteristics and microscopic characteristics of these two seeds were investigated, which could provide scientific evidence for the identification and classification of Astragali Complanati Semen. Our results showed that these two seeds were slightly different in the color and the appearance, but significantly different in the microstructure of the seed coat and the hilum, and the distribution of fat droplets in the cotyledon cells. So these microscopic characteristics can be applied for the identification of Astragali Complanati Semen.

  3. Scaled experiments using the helium technique to study the vehicular blockage effect on longitudinal ventilation control in tunnels

    DEFF Research Database (Denmark)

    Alva, Wilson Ulises Rojas; Jomaas, Grunde; Dederichs, Anne

    2015-01-01

    A model tunnel (1:30 compared to a standard tunnel section) with a helium-air smoke mixture was used to study the vehicular blockage effect on longitudinal ventilation smoke control. The experimental results showed excellent agreement with full-scale data and confirmed that the critical velocity...

  4. Carpal Tunnel Syndrome Associated with Oral Bisphosphonates. A Population-Based Cohort Study.

    Science.gov (United States)

    Carvajal, Alfonso; Martín Arias, Luis H; Sáinz, María; Escudero, Antonio; Fierro, Inmaculada; Sauzet, Odile; Cornelius, Victoria R; Molokhia, Mariam

    2016-01-01

    Bisphosphonates are widely used to prevent osteoporotic fractures. Some severe musculoskeletal reactions have been described with this medication; among them, some cases of carpal tunnel syndrome. Thus, the aim of this study was to explore whether bisphosphonates may be associated with this syndrome. A cohort study was conducted to compare exposed to unexposed women; the exposed group was that composed of women having received at least one prescription of an oral bisphosphonate. For the purpose, we used information from The Health Improvement Network (THIN) database. The outcome of interest was defined as those women diagnosed with carpal tunnel syndrome. A survival analysis was performed; the Cox proportional hazard model was used to calculate hazard ratios and 95% confidence intervals, and to adjust for identified confounding variables. Out of a sample of 59,475 women older than 51 years, 19,825 were treated with bisphosphonates during the period studied. No differences in age distribution or mean follow-up time were observed between the two groups in comparison. Overall, there were 572 women diagnosed with carpal tunnel syndrome, 242 (1.2%) in the group exposed to bisphosphonates, and 330 (0.8%) in the unexposed. An adjusted hazard ratio of developing carpal tunnel syndrome of 1.38 (95%CI, 1.15-1.64) was found for women exposed to bisphosphonates; no significant changes in the hazard ratios were found when considering different levels of bisphosphonate exposure. An increased risk of carpal tunnel syndrome is associated with the use of bisphosphonates in postmenopausal women.

  5. Wind Tunnel Model Design for Sonic Boom Studies of Nozzle Jet Flows with Shock Interactions

    Science.gov (United States)

    Cliff, Susan E.; Denison, Marie; Moini-Yekta, Shayan; Morr, Donald E.; Durston, Donald A.

    2016-01-01

    NASA and the U.S. aerospace industry are performing studies of supersonic aircraft concepts with low sonic boom pressure signatures. The computational analyses of modern aircraft designs have matured to the point where there is confidence in the prediction of the pressure signature from the front of the vehicle, but uncertainty remains in the aft signatures due to boundary layer and nozzle exhaust jet effects. Wind tunnel testing without inlet and nozzle exhaust jet effects at lower Reynolds numbers than in-flight make it difficult to accurately assess the computational solutions of flight vehicles. A wind tunnel test in the NASA Ames 9- by 7-Foot Supersonic Wind Tunnel is planned for February 2016 to address the nozzle jet effects on sonic boom. The experiment will provide pressure signatures of test articles that replicate waveforms from aircraft wings, tails, and aft fuselage (deck) components after passing through cold nozzle jet plumes. The data will provide a variety of nozzle plume and shock interactions for comparison with computational results. A large number of high-fidelity numerical simulations of a variety of shock generators were evaluated to define a reduced collection of suitable test models. The computational results of the candidate wind tunnel test models as they evolved are summarized, and pre-test computations of the final designs are provided.

  6. Numerical Study on Different Series Modes of Jet Fan in a Longitudinal Tunnel Ventilation System

    Directory of Open Access Journals (Sweden)

    Guihong Pei

    2014-01-01

    Full Text Available Efficient ventilation systems will contribute to maintaining air quality in the tunnel. In order to improve ventilation performance in normal traffic condition, the 3D tunnel models were established according to the original design for the tunnel located in central plains of China. Based on the commercial CFD software Fluent 6.3 and k-ε turbulence model, numerical simulations were carried out to study the patterns of jet flow and the optimization of fan combinations. It is found that the axial velocity profile obtained from numerical simulation agrees quite well with turbulent free jet theory although there is a little difference on the magnitude. The comparison of four combination modes under the condition of operating four fans indicates that the ventilation effectiveness is affected mainly by both the interval of adjacent groups of fans and the combination modes of operational fans. According to the simulation results, a novel combination mode which consists of a group double paralleled fans and two groups single fan is designed. The novel combination mode is regarded as the optimum combination mode with respect to maximizing air velocity in the tunnel. Compared to the traditional combination modes, it will increase the air velocity by 5.7%.

  7. Study on Oxygen Supply Standard for Physical Health of Construction Personnel of High-Altitude Tunnels

    Directory of Open Access Journals (Sweden)

    Chun Guo

    2015-12-01

    Full Text Available The low atmospheric pressure and low oxygen content in high-altitude environment have great impacts on the functions of human body. Especially for the personnel engaged in complicated physical labor such as tunnel construction, high altitude can cause a series of adverse physiological reactions, which may result in multiple high-altitude diseases and even death in severe cases. Artificial oxygen supply is required to ensure health and safety of construction personnel in hypoxic environments. However, there are no provisions for oxygen supply standard for tunnel construction personnel in high-altitude areas in current tunnel construction specifications. As a result, this paper has theoretically studied the impacts of high-altitude environment on human bodies, analyzed the relationship between labor intensity and oxygen consumption in high-altitude areas and determined the critical oxygen-supply altitude values for tunnel construction based on two different standard evaluation systems, i.e., variation of air density and equivalent PIO2. In addition, it has finally determined the oxygen supply standard for construction personnel in high-altitude areas based on the relationship between construction labor intensity and oxygen consumption.

  8. Ab initio simulation study of defect assisted Zener tunneling in GaAs diode

    Science.gov (United States)

    Lu, Juan; Fan, Zhi-Qiang; Gong, Jian; Jiang, Xiang-Wei

    2017-06-01

    The band to band tunneling of defective GaAs nano-junction is studied by using the non-equilibrium Green's function formalism with density functional theory. Aiming at performance improvement, two types of defect-induced transport behaviors are reported in this work. By examining the partial density of states of the system, we find the substitutional defect OAs that locates in the middle of tunneling region will introduce band-gap states, which can be used as stepping stones to increase the tunneling current nearly 3 times higher at large bias voltage (Vb≥0.3V). Another type of defects SeAs and VGa (Ga vacancy) create donor and acceptor states at the edge of conduction band (CB) and valence band (VB)respectively, which can change the band bending of the junction as well as increase the tunneling field obtaining a 1.5 times higher ON current. This provides an effective defect engineering approach for next generation TFET device design.

  9. Ab initio simulation study of defect assisted Zener tunneling in GaAs diode

    Directory of Open Access Journals (Sweden)

    Juan Lu

    2017-06-01

    Full Text Available The band to band tunneling of defective GaAs nano-junction is studied by using the non-equilibrium Green’s function formalism with density functional theory. Aiming at performance improvement, two types of defect-induced transport behaviors are reported in this work. By examining the partial density of states of the system, we find the substitutional defect OAs that locates in the middle of tunneling region will introduce band-gap states, which can be used as stepping stones to increase the tunneling current nearly 3 times higher at large bias voltage (Vb≥0.3V. Another type of defects SeAs and VGa (Ga vacancy create donor and acceptor states at the edge of conduction band (CB and valence band (VBrespectively, which can change the band bending of the junction as well as increase the tunneling field obtaining a 1.5 times higher ON current. This provides an effective defect engineering approach for next generation TFET device design.

  10. Oxidation mechanism of nickel particles studied in an environmental transmission electron microscope

    DEFF Research Database (Denmark)

    Jeangros, Q.; Hansen, Thomas Willum; Wagner, Jakob Birkedal

    2014-01-01

    The oxidation of nickel particles was studied in situ in an environmental transmission electron microscope in 3.2 mbar of O2 between ambient temperature and 600°C. Several different transmission electron microscopy imaging techniques, electron diffraction and electron energy-loss spectroscopy were...

  11. New microscope produced by Lambda Praha Co. applicable to field studies of microorganisms

    Czech Academy of Sciences Publication Activity Database

    Žižka, Zdeněk

    2008-01-01

    Roč. 53, č. 5 (2008), s. 457-461 ISSN 0015-5632 Institutional research plan: CEZ:AV0Z50200510 Keywords : lambda * microscope * field studies Subject RIV: EE - Microbiology, Virology Impact factor: 1.172, year: 2008

  12. Location of the root canal: Direct vision versus surgical microscope. In-vitro study.

    Directory of Open Access Journals (Sweden)

    Gabriela Sánchez

    2012-07-01

    Full Text Available The inability to properly identify the entrance to the root system, main and accessories, is one of the causes of endodontic failure. Hence arises the need to incorporate new technologies to improve the visibility of the access cavity to the location of the entrance to one of the root. The purpose of this study was to compare whether there is a difference between the location of root canals of human permanent molars through direct vision and using the surgical microscope. We examined 100 extracted human permanent molars first by direct vision and then using a surgical microscope to determine the number of root canals located. The difference was established for obtaining the real number of channels to make the cut root. Our study indicates that the number of root canals located increase in a 11% with the use of surgical microscope which is reflected in special conduits accessories which is consistent with other studies performed. It can be concluded from this study that the use of a surgical microscope were located a greater number of ducts in relation to the use of direct vision therefore is considered a useful tool to aid the clinician inconventional endodontic treatment, offering a fully operative fieldilluminated and magnified viewing with great detail, the floor of the chamber and the entrance to all canals, which is the key to success in endodontics.

  13. Carboxylic ester hydrolases in the thyroid gland of the guinea-pig. A light microscopic study

    DEFF Research Database (Denmark)

    Kirkeby, S

    1976-01-01

    The location of cholinesterase and non-specific esterase in the thyroid gland of the guniea-pig was studied with the light microscope. It was found that the idoxyl method for non-specific esterase activity under special conditions is superior to the cholinesterase method in a number of respects...

  14. Microscopic study of low-lying yrast spectra in Mo isotopes

    Indian Academy of Sciences (India)

    Microscopic study of low-lying yrast spectra in. 100-108. Mo isotopes. NEERU SAWHNEY, ARUN BHARTI and S K KHOSA. Department of Physics, Jammu University, Jammu 180 006, India. MS received 10 October 2001; revised 16 May 2002. Abstract. Variation-after-projection (VAP) calculations in conjunction with ...

  15. A microscopic study of deformation systematics in 154−166Dy ...

    Indian Academy of Sciences (India)

    a complete analysis, there is a need of a more elaborate microscopic nuclear theory. In view of this, we have planned to study the systematics of neutron rich even–even. 154−166. Dy isotopes, in a suitable ... action was fixed through the approximate relation G = (18 − 21)/A. The relative magnitudes of the parameters of the ...

  16. Poly(diacetylene) Monolayers Studied with a Fluorescence Scanning Near-Field Optical Microscope

    NARCIS (Netherlands)

    Moers, Marco H.P.; Moers, M.H.P.; Gaub, Hermann E.; van Hulst, N.F.

    1994-01-01

    A novel and powerful method to study the optical properties of thin lipid films which a resolution superior to confocal microscopy is presented. With a scanning near-field optical microscope, fluorescence images of a Langmuir-Blodgett film of diethylene glycol diamine pentacosadiynoic amide are

  17. [Scanning electron microscope study of dentin treated with sodium N-monochloro-DL2-aminobutyrate (NMAB)].

    Science.gov (United States)

    González Bahillo, J; Segade, L A; Gándara Rey, J; Macedo de Carvalho Capelas, M

    1989-02-01

    This paper report a scanning electron microscope study of the dentinal surface after treatment with sodium N-monochloro-DL2-aminobutyrate (NMAB). The carious cavity shows a rugous and irregular surface. There are detaching plates of the dentin dissolved by the NMAB. At high magnification the compact dentin and the detaching plates show a acid-etched surface.

  18. Microscopic study of positive-parity yrast bands of Th isotopes

    Indian Academy of Sciences (India)

    Microscopic study of positive-parity yrast bands of. 224−234. Th isotopes. DAYA RAM, RANI DEVI. ∗ and S K KHOSA. Department of Physics and Electronics, University of Jammu, Jammu 180 006, India. ∗. Corresponding author. E-mail: rani_rakwal@yahoo.co.in. MS received 16 November 2012; revised 8 February 2013; ...

  19. Microscopic study of low-lying collective bands in 77Kr

    Indian Academy of Sciences (India)

    Microscopic study of low-lying collective bands in 77Kr. K C TRIPATHY1, R SAHU2 and S MISHRA2. 1Department of Physics, North Orissa University, Baripada 757 003, India. 2Physics Department, Berhampur University, Berhampur 760 007, India. E-mail: rankasahu@rediffmail.com. MS received 26 May 2005; revised 21 ...

  20. Normal microscopic architecture of acetabular labrum of hip joint: a qualitative original study with clinical aspects.

    Science.gov (United States)

    Kapetanakis, Stylianos; Gkantsinikoudis, Nikolaos; Dermon, Antonios; Kommata, Vassiliki; Papathanasiou, Jannis; Soukakos, Panagiotis; Dermon, Caterina

    2017-01-01

    Normal histologic architecture of acetabular labrum, regarding presence of Free Nerve Endings (FNEs) and Nerve End Organs (NEOs) has been four times described. Nevertheless, elderly cadaveric specimens and individuals were recruited, leading to considerably high unreliability probability due to microscopic degenerative alterations. Aim of this paper is to analyze distribution pattern of FNEs and NEOs in acetabular labra of healthy middle-aged individuals, configuring thus more reliably acetabular labrum microscopic profile. Six patients with middle age 52 ± 2.5 years were enrolled in this study. Injury of acetabular labrum and normal hip radiograph were present in all cases. Patients were all subjected to successful hip hemi-arthroplasty and derived acetabular labra were subsequently histologically processed and observed under a compound microscope. FNEs and NEOs were detected in all specimens. All types of NEOs were identified, including Paccini, Golgi-Mazzoni, Ruffini and Krause corpuscles. FNEs and NEOs were both in ventral part and in chondral side of labrum predominantly detected. FNEs and NEOs presence was greater in ventral side of labrum, being thus in partial agreement with previous studies results. Further study is required, in order to elucidate the exact acetabular labrum normal microscopic anatomy. IV.

  1. Normal microscopic architecture of acetabular labrum of hip joint: a qualitative original study with clinical aspects

    Science.gov (United States)

    Kapetanakis, Stylianos; Gkantsinikoudis, Nikolaos; Dermon, Antonios; Kommata, Vassiliki; Papathanasiou, Jannis; Soukakos, Panagiotis; Dermon, Caterina

    2017-01-01

    Summary Background Normal histologic architecture of acetabular labrum, regarding presence of Free Nerve Endings (FNEs) and Nerve End Organs (NEOs) has been four times described. Nevertheless, elderly cadaveric specimens and individuals were recruited, leading to considerably high unreliability probability due to microscopic degenerative alterations. Aim of this paper is to analyze distribution pattern of FNEs and NEOs in acetabular labra of healthy middle-aged individuals, configuring thus more reliably acetabular labrum microscopic profile. Materials and methods Six patients with middle age 52 ± 2.5 years were enrolled in this study. Injury of acetabular labrum and normal hip radiograph were present in all cases. Patients were all subjected to successful hip hemi-arthroplasty and derived acetabular labra were subsequently histologically processed and observed under a compound microscope. Results FNEs and NEOs were detected in all specimens. All types of NEOs were identified, including Paccini, Golgi-Mazzoni, Ruffini and Krause corpuscles. FNEs and NEOs were both in ventral part and in chondral side of labrum predominantly detected. Conclusion FNEs and NEOs presence was greater in ventral side of labrum, being thus in partial agreement with previous studies results. Further study is required, in order to elucidate the exact acetabular labrum normal microscopic anatomy. Level of evidence IV. PMID:29264339

  2. Effect of Transosseous Tunnels on Patella Fracture Risk After Medial Patellofemoral Ligament Reconstruction: A Cadaveric Study.

    Science.gov (United States)

    Bonazza, Nicholas A; Lewis, Gregory S; Lukosius, Eric Z; Roush, Evan P; Black, Kevin P; Dhawan, Aman

    2018-02-01

    To determine whether (1) tunnels that breach the anterior cortex of the patella result in increased fracture risk and (2) transosseous tunnels drilled across the patella significantly reduce the tensile force needed to fracture the patella. Twenty-six fresh-frozen cadaveric human patellas were randomized to 1 of 3 groups: a control group with unmodified patellas, a group with 2 transverse tunnels (TT) that did not breach the anterior cortex, and a group with 2 TT that breached the anterior cortex of the patella (PA). Patellas were connected in series to a load cell via freeze clamp attachments to the quadriceps and patellar tendons. Pull was fixed at 45° with the patella set in the trochlear groove of a synthetic femur. Patellas were loaded cyclically, then to failure. Twenty-six patellas were tested (mean age = 71.4 years; range = 37-95, standard deviation [STD] = 11.5 years). PA patellas were more likely to fracture through the tunnel than TT patellas (100% vs 25%, P = .033). Control, TT, and PA groups failed at 1,915 N (STD = 508 N), 1,901 N (STD = 884 N), and 1,640 N (STD = 625 N), respectively. There was no statistically significant difference in overall load to failure between control and TT (P = .969), control and PA (P = .321), and TT and PA (P = .488) groups. Transosseous patellar tunnels for medial patellofemoral ligament reconstruction that breached the anterior cortex were more likely to fracture during longitudinal load than those that did not breach the anterior cortex. However, we found no statistically significant difference in the tensile load to failure between native patellas and patellas with either type of transosseous tunnel. The results of this study show that breaching the anterior cortex during transosseous drilling increases the risk of a patellar fracture occurring through the transosseous tunnel. Copyright © 2017 Arthroscopy Association of North America. Published by Elsevier Inc. All rights reserved.

  3. Ultrafast scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Botkin, D.A. [California Univ., Berkeley, CA (United States). Dept. of Physics]|[Lawrence Berkeley Lab., CA (United States)

    1995-09-01

    I have developed an ultrafast scanning tunneling microscope (USTM) based on uniting stroboscopic methods of ultrafast optics and scanned probe microscopy to obtain nanometer spatial resolution and sub-picosecond temporal resolution. USTM increases the achievable time resolution of a STM by more than 6 orders of magnitude; this should enable exploration of mesoscopic and nanometer size systems on time scales corresponding to the period or decay of fundamental excitations. USTM consists of a photoconductive switch with subpicosecond response time in series with the tip of a STM. An optical pulse from a modelocked laser activates the switch to create a gate for the tunneling current, while a second laser pulse on the sample initiates a dynamic process which affects the tunneling current. By sending a large sequence of identical pulse pairs and measuring the average tunnel current as a function of the relative time delay between the pulses in each pair, one can map the time evolution of the surface process. USTM was used to measure the broadband response of the STM`s atomic size tunnel barrier in frequencies from tens to hundreds of GHz. The USTM signal amplitude decays linearly with the tunnel junction conductance, so the spatial resolution of the time-resolved signal is comparable to that of a conventional STM. Geometrical capacitance of the junction does not appear to play an important role in the measurement, but a capacitive effect intimately related to tunneling contributes to the measured signals and may limit the ultimate resolution of the USTM.

  4. Large-field high-resolution x-ray microscope for studying laser plasmas

    International Nuclear Information System (INIS)

    Sauneuf, R.; Dalmasso, J.; Jalinaud, T.; Le Breton, J.; Schirmann, D.; Marioge, J.; Bridou, F.; Tissot, G.; Clotaire, J.

    1997-01-01

    In 1948, P. Kirkpatrick and A. V. Baez developed an x-ray microscope (energy range about 100 eV endash 10 keV) composed of two concave spherical mirrors working at grazing incidence. That device, named KB microscope, presents a 3 endash 5 μm resolution within a field having a radius about 100 μm; outside that field, its resolution lowers rapidly when the object point recedes from the center. The adjunction of two similar mirrors can notably increase the useful field (typically, the resolution can be better than 10 μm within a 2-mm-diam field of view), which is necessary for studying laser plasmas. Its main advantage with respect to more simple optics, as the pinhole, is that it can be located far enough from the plasma to avoid any destruction during the shot. We describe such a microscope that we call KBA microscope and present some images of fine metallic grids. Those grids were backlighted by x-ray sources, either a cw one or a series of laser plasmas from the Octal endash Hacute eliotrope facility. Examining the films in detail shows that the experimental results are very close to the theoretical characteristics; hence the interest of this device for the x-ray diagnostics on the future powerful laser facilities. copyright 1997 American Institute of Physics

  5. The diagnostic efficacy of clinical findings and electrophysiological studies in carpal tunnel syndrome

    OpenAIRE

    Buyukkoyuncu Pekel, Nilufer; Nar Senol, Pelin; Yildiz, Demet; Kilic, Ahmet Kasim; Kamaci Sener, Deniz; Seferoglu, Meral; Gunes, Aygul

    2017-01-01

    Objective. The aim of the study was to examine the relation between clinical findings, neurological examination and electrophysiological studies in diagnosing carpal tunnel syndrome (CTS) and share our institutional experience in patients with CTS. Methods. Patients presenting with complaints of pain, paresthesia, and weakness in hands who diagnosed CTS between 2014 and 2015 were examined retrospectively. Demographic characteristics, clinical and neurological examination findings and electrod...

  6. Study of skin of an Egyptian mummy using a scanning electron microscope

    Directory of Open Access Journals (Sweden)

    Mańkowska-Pliszka Hanna

    2017-06-01

    Full Text Available The first study of modified human remains using an electron microscope was carried out at the end of the 1950 and in 1979 the first result of the study involving a scanning electron microscope (SEM was published for the first time. The study was mainly focused on the structure of tissues and cells. With the help of this technique cell and tissue elements, viruses and bacterial endospores as well as the structure of epithelium and the collagen contents of dermis were identified and described. In the above-mentioned case the object of the study using a SEM was a free part of the right hand (forearm with the dorsal and palmar parts of hand of unknown origin, with signs of mummification revealed during microscopic analysis. Our study was aimed at finding the answer to the question if the mummification of the studied limb was natural or intentional, and if the study using a SEM could link the anonymous remains with ancient Egypt.

  7. Pulse Plating on Gold Surfaces Studied by In Situ Scanning Tunneling Microscopy

    DEFF Research Database (Denmark)

    Andersen, Jens Enevold Thaulov; Bech-Nielsen, Gregers; Møller, Per

    1994-01-01

    Deposition of bulk copper on thin film gold surfaces is carried out by computer-aided pulse plating. It is demonstrated that the morphology of the copper deposit can be studied by in situ scanning tunnelling microscopy both in potentiostatic experiments and in galvanostatic experiments. Optimized...... procedures for obtaining smooth deposits by pulse plating are explained in terms of a levelling effect. Possible non-faradaic processes observed in measurements with high frequency pulse plating are discussed....

  8. Study of optical techniques for the Ames unitary wind tunnel. Part 5: Infrared imagery

    Science.gov (United States)

    Lee, George

    1992-01-01

    A survey of infrared thermography for aerodynamics was made. Particular attention was paid to boundary layer transition detection. IR thermography flow visualization of 2-D and 3-D separation was surveyed. Heat transfer measurements and surface temperature measurements were also covered. Comparisons of several commercial IR cameras were made. The use of a recently purchased IR camera in the Ames Unitary Plan Wind Tunnels was studied. Optical access for these facilities and the methods to scan typical models was investigated.

  9. Facility for low-temperature spin-polarized-scanning tunneling microscopy studies of magnetic/spintronic materials prepared in situ by nitride molecular beam epitaxy.

    Science.gov (United States)

    Lin, Wenzhi; Foley, Andrew; Alam, Khan; Wang, Kangkang; Liu, Yinghao; Chen, Tianjiao; Pak, Jeongihm; Smith, Arthur R

    2014-04-01

    Based on the interest in, as well as exciting outlook for, nitride semiconductor based structures with regard to electronic, optoelectronic, and spintronic applications, it is compelling to investigate these systems using the powerful technique of spin-polarized scanning tunneling microscopy (STM), a technique capable of achieving magnetic resolution down to the atomic scale. However, the delicate surfaces of these materials are easily corrupted by in-air transfers, making it unfeasible to study them in stand-alone ultra-high vacuum STM facilities. Therefore, we have carried out the development of a hybrid system including a nitrogen plasma assisted molecular beam epitaxy/pulsed laser epitaxy facility for sample growth combined with a low-temperature, spin-polarized scanning tunneling microscope system. The custom-designed molecular beam epitaxy growth system supports up to eight sources, including up to seven effusion cells plus a radio frequency nitrogen plasma source, for epitaxially growing a variety of materials, such as nitride semiconductors, magnetic materials, and their hetero-structures, and also incorporating in situ reflection high energy electron diffraction. The growth system also enables integration of pulsed laser epitaxy. The STM unit has a modular design, consisting of an upper body and a lower body. The upper body contains the coarse approach mechanism and the scanner unit, while the lower body accepts molecular beam epitaxy grown samples using compression springs and sample skis. The design of the system employs two stages of vibration isolation as well as a layer of acoustic noise isolation in order to reduce noise during STM measurements. This isolation allows the system to effectively acquire STM data in a typical lab space, which during its construction had no special and highly costly elements included, (such as isolated slabs) which would lower the environmental noise. The design further enables tip exchange and tip coating without

  10. Facility for low-temperature spin-polarized-scanning tunneling microscopy studies of magnetic/spintronic materials prepared in situ by nitride molecular beam epitaxy

    International Nuclear Information System (INIS)

    Lin, Wenzhi; Foley, Andrew; Alam, Khan; Wang, Kangkang; Liu, Yinghao; Chen, Tianjiao; Pak, Jeongihm; Smith, Arthur R.

    2014-01-01

    Based on the interest in, as well as exciting outlook for, nitride semiconductor based structures with regard to electronic, optoelectronic, and spintronic applications, it is compelling to investigate these systems using the powerful technique of spin-polarized scanning tunneling microscopy (STM), a technique capable of achieving magnetic resolution down to the atomic scale. However, the delicate surfaces of these materials are easily corrupted by in-air transfers, making it unfeasible to study them in stand-alone ultra-high vacuum STM facilities. Therefore, we have carried out the development of a hybrid system including a nitrogen plasma assisted molecular beam epitaxy/pulsed laser epitaxy facility for sample growth combined with a low-temperature, spin-polarized scanning tunneling microscope system. The custom-designed molecular beam epitaxy growth system supports up to eight sources, including up to seven effusion cells plus a radio frequency nitrogen plasma source, for epitaxially growing a variety of materials, such as nitride semiconductors, magnetic materials, and their hetero-structures, and also incorporating in situ reflection high energy electron diffraction. The growth system also enables integration of pulsed laser epitaxy. The STM unit has a modular design, consisting of an upper body and a lower body. The upper body contains the coarse approach mechanism and the scanner unit, while the lower body accepts molecular beam epitaxy grown samples using compression springs and sample skis. The design of the system employs two stages of vibration isolation as well as a layer of acoustic noise isolation in order to reduce noise during STM measurements. This isolation allows the system to effectively acquire STM data in a typical lab space, which during its construction had no special and highly costly elements included, (such as isolated slabs) which would lower the environmental noise. The design further enables tip exchange and tip coating without

  11. Study of grain boundary tunneling in barium-titanate ceramic films

    CERN Document Server

    Wong, H; Poon, M C

    1999-01-01

    The temperature and the electric-field dependences of the current-voltage characteristics and the low-frequency noise of barium-titanate ceramic films are studied. An abnormal field dependence is observed in the resistivity of BaTiO sub 3 materials with a small average grain size. In addition, experiments show that the low-frequency noise behaviors are governed by grain-boundary tunneling at room temperature and by trapping-detrapping of grain-boundary states at temperatures above the Curie point. Physical models for the new observations are developed. Results suggest that grain-boundary tunneling of carriers is as important as the double Schottky barrier in the current conduction in BaTiO sub 3 materials with small grain sizes.

  12. An experimental study of high contraction ratio, subsonic wind tunnel inlets

    Science.gov (United States)

    Caylor, M. J.; Batill, S. M.

    1984-01-01

    The inlet or contraction section has significant impact on the performance and operating characteristics of any subsonic wind tunnel. Previous experimental studies have been conducted to examine specific aspects of inlet performance and design. This work builds on this earlier experience by performing a comprehensive experimental analysis of a member of a family of high contraction ratio inlets used on indraft type wind tunnels. Quantitative flow field measurements were made using wall static ports, a five-hole pressure probe, and a hot wire anemometry system. Smoke flow visualization techniques were used to examine the inlet flow in a more qualitative manner and to correlate with quantitative measurements. This experimental investigation has provided insight into some of the many problems associated with inlet flows.

  13. Comparative study of construction schemes for proposed LINAC tunnel for ADSS

    International Nuclear Information System (INIS)

    Parchani, G.; Suresh, N.

    2003-01-01

    Radiation shielded structures involve architectural, structural and radiation shielding design. In order to attenuate the radiation level to the permissible limits concrete has been recognized as a most versatile radiation shielding material and is being extensively used. Concrete in addition to radiation shielding properties possesses very good mechanical properties, which enables its use as a structural member. High-energy linac lab, which will generate radiation, needs very large thickness of concrete for shielding. The length of tunnel (1.00 kM) is one of the most important factors in finalizing construction scheme. In view of this, it becomes essential to explore alternate construction schemes for such structures to optimize the cost of construction. In this paper, various alternates for the construction of proposed linac tunnel have been studied

  14. A computational study of vertical tunneling transistors based on graphene-WS2 heterostructure

    Science.gov (United States)

    Horri, A.; Faez, R.; Pourfath, M.; Darvish, G.

    2017-06-01

    In this paper, for the first time, we present a computational study on electrical characteristics of field effect tunneling transistors based on a vertical graphene-WS2 heterostructure and vertical graphene nanoribbon (GNR)-WS2 heterostructure (VTGNRFET). Our model uses the nonequilibrium Green's function formalism along with an atomistic tight binding (TB) method. The TB parameters are extracted by fitting the bandstructure to first principles results. We show that, due to the advantage of switching between tunneling and thermionic transport regimes, an improvement can be achieved in the electrical characteristics of the device. We find that the increase of the number of WS2 layers enhances the on/off conductance ratio but degrades the intrinsic gate-delay time. The results indicate that the on/off conductance ratio of VTGNRFET increases with decreasing the GNR width.

  15. Experimental Study on the Tensile Strength and Linear Expansion Coefficient of Air Tunnel Terrazzo Surface

    Directory of Open Access Journals (Sweden)

    Boping Li

    2015-01-01

    Full Text Available At present, studies on the surface tension of air tunnel terrazzo under wind load and how regularly it is affected by temperature are relatively less, and the measured results of the thermal expansion coefficient of terrazzo have not yet been given. In this paper, based on the top terrazzo surface structure of the inner wall of the wind tunnel, the tensile performance tests of terrazzo surface layer are conducted, while the thermal expansion coefficient of the six terrazzo test blocks were tested. The tests and analysis show that the construction of terrazzo surface, based on the proposed construction process, can effectively guarantee the reliable cement performance for the binding layer between mortar and concrete base layer, terrazzo surface layer and the cement mortar layer. And the thermal expansion coefficient of terrazzo can be valued at 1.06e-5/ºC.

  16. Pleomorphic (giant cell) carcinoma of the intestine. An immunohistochemical and electron microscopic study

    DEFF Research Database (Denmark)

    Bak, Martin; Teglbjaerg, P S

    1989-01-01

    Pleomorphic (giant cell) carcinomas have been described in the lungs, thyroid, pancreas, and gallbladder. Two pleomorphic carcinomas of the small bowel and two of the large bowel are presented. On light microscopic study, the carcinomas were solid, without squamous or glandular differentiation....... The tumors were composed of the following three cell types: gemistocytic (giant) cells, smaller polygonal cells, and spindle cells, with identical immunohistochemical reactions. A panel of monoclonal and polyclonal antibodies was applied. All tumors were found to coexpress keratin and vimentin. A positive...... reaction for neuron-specific enolase (NSE) was found in three tumors and a positive reaction for chromogranin was found in one tumor. On electron microscopic study, intracytoplasmic whorls of intermediate filaments were seen in the perinuclear area. Dense core "neurosecretory" granules were rarely seen...

  17. Microsystem Aeromechanics Wind Tunnel

    Data.gov (United States)

    Federal Laboratory Consortium — The Microsystem Aeromechanics Wind Tunnel advances the study of fundamental flow physics relevant to micro air vehicle (MAV) flight and assesses vehicle performance...

  18. Tunneling of electrons via rotor–stator molecular interfaces: Combined ab initio and model study

    Energy Technology Data Exchange (ETDEWEB)

    Petreska, Irina, E-mail: irina.petreska@pmf.ukim.mk [Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, PO Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Ohanesjan, Vladimir [Institute of Physics, Faculty of Natural Sciences and Mathematics, Ss. Cyril and Methodius University, PO Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Pejov, Ljupčo [Institute of Chemistry, Department of Physical Chemistry, Ss. Cyril and Methodius University, Arhimedova 5, P.O. Box 162, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Kocarev, Ljupčo [Macedonian Academy of Sciences and Arts, Krste Misirkov 2, PO Box 428, 1000 Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of); Faculty of Computer Science and Engineering, Ss. Cyril and Methodius University, Skopje, Former Yugolav Republic of Macedonia, The (Macedonia, The Former Yugoslav Republic of)

    2016-07-01

    Tunneling of electrons through rotor–stator anthracene aldehyde molecular interfaces is studied with a combined ab initio and model approach. Molecular electronic structure calculated from first principles is utilized to model different shapes of tunneling barriers. Together with a rectangular barrier, we also consider a sinusoidal shape that captures the effects of the molecular internal structure more realistically. Quasiclassical approach with the Simmons’ formula for current density is implemented. Special attention is paid on conformational dependence of the tunneling current. Our results confirm that the presence of the side aldehyde group enhances the interesting electronic properties of the pure anthracene molecule, making it a bistable system with geometry dependent transport properties. We also investigate the transition voltage and we show that conformation-dependent field emission could be observed in these molecular interfaces at realistically low voltages. The present study accompanies our previous work where we investigated the coherent transport via strongly coupled delocalized orbital by application of Non-equilibrium Green’s Function Formalism.

  19. Risk factors for operated carpal tunnel syndrome: a multicenter population-based case-control study

    Directory of Open Access Journals (Sweden)

    Mandes Anna

    2009-09-01

    Full Text Available Abstract Background Carpal tunnel syndrome (CTS is a socially and economically relevant disease caused by compression or entrapment of the median nerve within the carpal tunnel. This population-based case-control study aims to investigate occupational/non-occupational risk factors for surgically treated CTS. Methods Cases (n = 220 aged 18-65 years were randomly drawn from 13 administrative databases of citizens who were surgically treated with carpal tunnel release during 2001. Controls (n = 356 were randomly sampled from National Health Service registry records and were frequency matched by age-gender-specific CTS hospitalization rates. Results At multivariate analysis, risk factors were blue-collar/housewife status, BMI ≥ 30 kg/m2, sibling history of CTS and coexistence of trigger finger. Being relatively tall (cut-offs based on tertiles: women ≥165 cm; men ≥175 cm was associated with lower risk. Blue-collar work was a moderate/strong risk factor in both sexes. Raised risks were apparent for combinations of biomechanical risk factors that included frequent repetitivity and sustained force. Conclusion This study strongly underlines the relevance of biomechanical exposures in both non-industrial and industrial work as risk factors for surgically treated CTS.

  20. Risk factors for operated carpal tunnel syndrome: a multicenter population-based case-control study.

    Science.gov (United States)

    Mattioli, Stefano; Baldasseroni, Alberto; Bovenzi, Massimo; Curti, Stefania; Cooke, Robin M T; Campo, Giuseppe; Barbieri, Pietro G; Ghersi, Rinaldo; Broccoli, Marco; Cancellieri, Maria Pia; Colao, Anna Maria; Dell'omo, Marco; Fateh-Moghadam, Pirous; Franceschini, Flavia; Fucksia, Serenella; Galli, Paolo; Gobba, Fabriziomaria; Lucchini, Roberto; Mandes, Anna; Marras, Teresa; Sgarrella, Carla; Borghesi, Stefano; Fierro, Mauro; Zanardi, Francesca; Mancini, Gianpiero; Violante, Francesco S

    2009-09-16

    Carpal tunnel syndrome (CTS) is a socially and economically relevant disease caused by compression or entrapment of the median nerve within the carpal tunnel. This population-based case-control study aims to investigate occupational/non-occupational risk factors for surgically treated CTS. Cases (n = 220) aged 18-65 years were randomly drawn from 13 administrative databases of citizens who were surgically treated with carpal tunnel release during 2001. Controls (n = 356) were randomly sampled from National Health Service registry records and were frequency matched by age-gender-specific CTS hospitalization rates. At multivariate analysis, risk factors were blue-collar/housewife status, BMI > or = 30 kg/m2, sibling history of CTS and coexistence of trigger finger. Being relatively tall (cut-offs based on tertiles: women > or =165 cm; men > or =175 cm) was associated with lower risk. Blue-collar work was a moderate/strong risk factor in both sexes. Raised risks were apparent for combinations of biomechanical risk factors that included frequent repetitivity and sustained force. This study strongly underlines the relevance of biomechanical exposures in both non-industrial and industrial work as risk factors for surgically treated CTS.

  1. Microscopic structural study of collagen aging in isolated fibrils using polarized second harmonic generation

    Science.gov (United States)

    Aït-Belkacem, Dora; Guilbert, Marie; Roche, Muriel; Duboisset, Julien; Ferrand, Patrick; Sockalingum, Ganesh; Jeannesson, Pierre; Brasselet, Sophie

    2012-08-01

    Polarization resolved second harmonic generation (PSHG) is developed to study, at the microscopic scale, the impact of aging on the structure of type I collagen fibrils in two-dimensional coatings. A ribose-glycated collagen is also used to mimic tissue glycation usually described as an indicator of aging. PSHG images are analyzed using a generic approach of the molecular disorder information in collagen fibrils, revealing significant changes upon aging, with a direct correlation between molecular disorder and fibril diameters.

  2. Study on the structure of pitch-polymer compositions by fluorescence microscope

    OpenAIRE

    Makomaski, Grzegorz

    2014-01-01

    In this work, the results of studies on the evaluation of colloidal structure of coal-tar pitch compositions with selected waste polymers by fluorescence microscope. For pitch-polymer compositions containing 10?50?wt% waste polymer, softening point, coking value and content of components insoluble in toluene and quinoline were carried out. The results indicate that pitch-polymer compositions can be treated as microheterogeneous systems, colloidal and biphase, generally exhibiting uniform disp...

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

    International Nuclear Information System (INIS)

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

    1993-08-01

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

  4. EXAFS study influence of pH on microscopic structure of zinc

    International Nuclear Information System (INIS)

    Li Xianliang; Chongqing Entry-Exit Inspection and Quarantine Bureau, Chongqing; Pan Gang; Zhu Mengqiang; Chen Hao; Hu Tiandou; Wu Ziyu; Xie Yaning; Du Yonghua

    2004-01-01

    Microscopic local structures of Zn(II) were studied using extended X-ray absorption fine structure (EXAFS) spectroscopy under different pH conditions. When pH 2+ (aq) was coordinated with six water molecules and the average Zn-O distance was measured to be 2.08 Angstrom, which indicated that hydrated Zn 2+ (aq) ions were in octahedral geometry under acid conditions. Under alkaline conditions, Zn 2+ (aq) was coordinated with four water molecules and the average Zn-O distance was measured to be 1.96 Angstrom, which indicated that hydrated Zn 2+ (aq) ions were in tetrahedral geometry. EXAFS results provided detailed information on the form and microscopic structure of hydrated Zn(II) ions under different pH conditions, which were fundamental for understanding the reactivity of Zn(II) in solutions and at particle-water interfaces. (authors)

  5. Case Studies for the Statistical Design of Experiments Applied to Powered Rotor Wind Tunnel Tests

    Science.gov (United States)

    Overmeyer, Austin D.; Tanner, Philip E.; Martin, Preston B.; Commo, Sean A.

    2015-01-01

    The application of statistical Design of Experiments (DOE) to helicopter wind tunnel testing was explored during two powered rotor wind tunnel entries during the summers of 2012 and 2013. These tests were performed jointly by the U.S. Army Aviation Development Directorate Joint Research Program Office and NASA Rotary Wing Project Office, currently the Revolutionary Vertical Lift Project, at NASA Langley Research Center located in Hampton, Virginia. Both entries were conducted in the 14- by 22-Foot Subsonic Tunnel with a small portion of the overall tests devoted to developing case studies of the DOE approach as it applies to powered rotor testing. A 16-47 times reduction in the number of data points required was estimated by comparing the DOE approach to conventional testing methods. The average error for the DOE surface response model for the OH-58F test was 0.95 percent and 4.06 percent for drag and download, respectively. The DOE surface response model of the Active Flow Control test captured the drag within 4.1 percent of measured data. The operational differences between the two testing approaches are identified, but did not prevent the safe operation of the powered rotor model throughout the DOE test matrices.

  6. Percutaneous Ultrasound-Guided Carpal Tunnel Release: Study Upon Clinical Efficacy and Safety

    Energy Technology Data Exchange (ETDEWEB)

    Petrover, David, E-mail: dpetrover@yahoo.fr; Silvera, Jonathan, E-mail: silvera.jonathan@gmail.com [Imagerie Médicale Paris Centre Bachaumont-clinique Blomet RamsayGDS, Department of Interventional Radiology (France); Baere, Thierry De, E-mail: Debaere@igr.fr [Gustave Roussy Institute (France); Vigan, Marie, E-mail: marie.vigan@gmail.com [Association pour la recherche en chirurgie de l’épaule et du coude, clinique Drouot (France); Hakimé, Antoine, E-mail: thakime@yahoo.com [Imagerie Médicale Paris Centre Bachaumont-clinique Blomet RamsayGDS, Department of Interventional Radiology (France)

    2017-04-15

    ObjectivesTo evaluate the feasibility and 6 months clinical result of sectioning of the transverse carpal ligament (TCL) and median nerve decompression after ultra-minimally invasive, ultrasound-guided percutaneous carpal tunnel release (PCTR) surgery.MethodsConsecutive patients with carpal tunnel syndrome were enrolled in this descriptive, open-label study. The procedure was performed in the interventional radiology room. Magnetic resonance imaging was performed at baseline and 1 month. The Boston Carpal Tunnel Questionnaire was administered at baseline, 1, and 6 months.Results129 patients were enrolled. Significant decreases in mean symptom severity scores (3.3 ± 0.7 at baseline, 1.7 ± 0.4 at Month 1, 1.3 ± 0.3 at Month 6) and mean functional status scores (2.6 ± 1.1 at baseline, 1.6 ± 0.4 at Month 1, 1.3 ± 0.5 at Month 6) were noted. Magnetic resonance imaging showed a complete section of all TCL and nerve decompression in 100% of patients. No complications were identified.ConclusionsUltrasound-guided PCTR was used successfully to section the TCL, decompress the median nerve, and reduce self-reported symptoms.

  7. Finite element analysis of high aspect ratio wind tunnel wing model: A parametric study

    Science.gov (United States)

    Rosly, N. A.; Harmin, M. Y.

    2017-12-01

    Procedure for designing the wind tunnel model of a high aspect ratio (HAR) wing containing geometric nonlinearities is described in this paper. The design process begins with identification of basic features of the HAR wing as well as its design constraints. This enables the design space to be narrowed down and consequently, brings ease of convergence towards the design solution. Parametric studies in terms of the spar thickness, the span length and the store diameter are performed using finite element analysis for both undeformed and deformed cases, which respectively demonstrate the linear and nonlinear conditions. Two main criteria are accounted for in the selection of the wing design: the static deflections due to gravitational loading should be within the allowable margin of the size of the wind tunnel test section and the flutter speed of the wing should be much below the maximum speed of the wind tunnel. The findings show that the wing experiences a stiffness hardening effect under the nonlinear static solution and the presence of the store enables significant reduction in linear flutter speed.

  8. Electron microscopic study of the spilt irradiation effects on the rat parotid ductal cells

    International Nuclear Information System (INIS)

    Kim, Sung Soo; Lee, Sang Rae

    1988-01-01

    This study was designed to investigate the effects of split irradiation on the salivary ductal cells, especially on the intercalated cells of the rat parotid glands. For this study, 24 Sprague-Dawley strain rats were irradiated on the head and neck region with two equal split doses of 9 Gy for a 4 hours interval by Co-60 teletherapy unit, Picker's mode l 4M 60. The conditions of irradiation were that field size, dose rate, SSD and depth were 12 X 5 cm, 222 cGy/min, 50 cm and 1 cm, respectively. The experimental animals were sacrificed 1, 2, 3, 6, 12, hours and 1, 3, 7, days after the irradiation and the changes of the irradiated intercalated cells of the parotid glands were examined under light and electron microscope. The results were as follows: 1. By the split irradiation, the degenerative changes of intercalated cells of the parotid glands appeared at 3 hours after irradiation and the most severe cellular degeneration observed at 6 hours after irradiation. The repair processes began from 12 hours after irradiation and have matured progressively. 2. Under electron microscope, loss of nuclear membrane, microvilli and secretory granules, derangement of chromosomes, degeneration of cytoplasm, atrophy or reduction of intracytoplasmic organelles were observed in the intercalated ductal cells after split irradiation. 3. Under light microscope, derangement of ductal cells, widening of cytoplasms and nuclei, hyperchromatism and proliferation of ductal cells were observed in intercalated ducts after split irradiation.

  9. Microscopic studies on postmortem vermiform appendix of the adult males of Bangladesh.

    Science.gov (United States)

    Bakar, S M A; Shamim, M; Salam, A; Sultana, S A

    2016-02-01

    The anatomy of the vermiform appendix shows variations in its macroscopic dimensions and microscopic features, some of which have potentials of influencing the clinical aspects of the appendix. The aim of this study was to find out some microscopic features of appendix and evaluate the correlation between the microscopic features of the appendix and the age of the subjects and to determine whether these findings should influence the clinical implications of appendix. In this cross-sectional observational study, thirty adult males' (age from 18 to 67 years) postmortem appendices and adnexa from Bangladeshi victims of road traffic accidents were sectioned at the base, midzone and tip stained with H+E stain and examined under microscope. Measurements were taken at the base, at the midzone and at the tip of the appendix, and the mean of the three measurements was considered as the overall value. The overall number of mucosal glands in a section ranged from 42.33 to 130.00 and the number of the germinal centres varied between 2.33 and 10.00. The overall luminal diameter ranged between 1764.58 and 3208.33 µm. The overall luminal diameter in more than 52 % of cases was between 2700.00 and 3299.99 µm with a median value of 2750 µm. The overall number of mucosal glands showed a tendency towards a positive correlation with age. The overall luminal diameter and the overall number of germinal centres showed a tendency towards a negative correlation with the age. However, none of the tendencies of correlation reached statistically any significant level.

  10. A prospective study of prognostic factors for duration of sick leave after endoscopic carpal tunnel release

    Directory of Open Access Journals (Sweden)

    Dalsgaard Jesper

    2009-11-01

    Full Text Available Abstract Background Endoscopic carpal tunnel release with a single portal technique has been shown to reduce sick leave compared to open carpal tunnel release, claiming to be a less invasive procedure and reducing scar tenderness leading to a more rapid return to work, and the purpose of this study was to identify prognostic factors for prolonged sick leave after endoscopic carpal tunnel release in a group of employed Danish patients. Methods The design was a prospective study including 75 employed patients with carpal tunnel syndrome operated with ECTR at two hospitals. The mean age was 46 years (SD 10.1, the male/female ratio was 0.42, and the mean preoperative duration of symptoms 10 months (range 6-12. Only 21 (28% were unable to work preoperatively and mean sick leave was 4 weeks (range 1-4. At base-line and at the 3-month follow-up, a self-administered questionnaire was collected concerning physical, psychological, and social circumstances in relation to the hand problem. Data from a nerve conduction examination were collected at baseline and at the 3-month follow-up. Significant prognostic factors were identified through multiple logistic regression analysis. Results After the operation, the mean functional score was reduced from 2.3 to 1.4 (SD 0.8 and the mean symptom score from 2.9 to 1.5 (SD 0.7. The mean sick leave from work after the operation was 19.8 days (SD 14.3. Eighteen patients (24% had more than 21 days of sick leave. Two patients (3% were still unable to work after 3 months. Significant prognostic factors in the multivariate analysis for more than 21 days of postoperative sick leave were preoperative sick leave, blaming oneself for the hand problem and a preoperative distal motor latency. Conclusion Preoperative sick leave, blaming oneself for the hand problem, and a preoperative distal nerve conduction motor latency were prognostic factors for postoperative work absence of more than 21 days. Other factors may be important

  11. Magnifying loupes versus surgical microscope in endodontic surgery: a four-year retrospective study.

    Science.gov (United States)

    Taschieri, Silvio; Weinstein, Tommaso; Tsesis, Igor; Bortolin, Monica; Del Fabbro, Massimo

    2013-08-01

    The purpose of this retrospective study was to evaluate the 4-year outcome of endodontic microsurgery using two different magnification devices. One-hundred and two teeth in 65 patients were included according to specific selection criteria. Endodontic surgery was performed under surgical microscope as magnification device in 63 teeth in 36 patients, while 39 teeth in 29 patients were treated under magnifying loupes. Thirteen patients did not attend the 4-year follow up. The overall success rate on a patient basis was 91.7% at the 1-year and 90.5% at the 4-year follow up for the group using loupes, while for the group using microscope it was 91.4% at the 1-year and 93.3% at the 4-year follow up. The relative risk was 2.07 (95% confidence interval: 0.31, 13.95) in favour of the group in which microscope was used. No statistically significant difference was found in the treatment outcomes relating to the type of magnification device. © 2011 The Authors. Australian Endodontic Journal © 2011 Australian Society of Endodontology.

  12. [Macro-microscopic comparative study of gallbladder lesions in La Plata (Argentina)].

    Science.gov (United States)

    Corrons, F J; Sidoti Hartmann, A N; Castelletto, R H

    1994-01-01

    The histogenesis of the gallbladder carcinoma is under controversy Some authors emphasize the polyp-cancer sequence, whereas others relate the adenocarcinoma with metaplastic and dysplastic changes. It is important to examine immediately the characteristics of the mucosa, in order for guidance to the surgeon at the operating room. With the purpose of correlating the macro-microscopic findings of gallbladder lesions, we studied 306 gallbladder specimens extended and fixed in formaline. We considered: Age, sex, lithiasis, dimensions of the specimens and macroscopic patterns of the mucosal surface. Longitudinal samples were taken for histological examination. Two hundred and thirty seven cases corresponded to female sex (77.4%) and 69 to male sex (22.5%) with an average age of 44 years. Among the microscopic findings, we found gastric metaplasia in 43% of the cases, intestinal metaplasia in 10.8%, low grade dysplasia in 11.8% and high grade dysplasia in 1.6%, and 2 cases of clinically unsuspected invasive carcinomas (0.6%). An association between chronic colecistitis, lithiasis and epithelial changes was confirmed, but the relation between each one of the macroscopic patterns proposed and the histological findings is statistically significant only in the cases of atrophy, probably owing to the overlapping of microscopic findings in the different macroscopic patterns.

  13. Study of tunnelling through water-bearing fracture zones. Baseline study on technical issues with NE-1 as reference

    Energy Technology Data Exchange (ETDEWEB)

    Yanting Chang; Swindell, Robert; Bogdanoff, Ingvar; Lindstroem, Beatrice; Termen, Jens [WSP Sweden, Stockholm (Sweden) ; Starsec, Peter [SGI, Linkoeping (Sweden)

    2005-04-01

    The Swedish Nuclear Fuel and Waste Management Co (SKB) is responsible for the management of Sweden's nuclear waste. SKB is investigating various designs for the construction of an underground deep repository for spent nuclear fuel at 500-600 m depths. For the construction of an access tunnel for such a deep repository, the possibility of encountering a water-bearing fracture zone cannot be discounted. Such a zone named NE-1 (deformation zone in accordance to SKB's terminology) was encountered during the construction of the Aespoe Hard Rock Laboratory (HRL) and difficulties with large water inflows were reported. With the aim to assess the feasibility of different technical solutions, SKB commissioned a baseline study into the passage of an access tunnel through a water-bearing fracture zone at three different depths (200 m, 400 m and 600 m). The objectives of this baseline study are to: Increase the knowledge of possible technical solutions for tunnelling through water-bearing fractures zones with the characteristics of the brittle deformation zone NE-1 at different depths, namely 200, 400 and 600 metres; Form a reference document to assist the engineering design and construction work for the passage through such a water-bearing fracture zone; To highlight the engineering parameters that should be obtained to facilitate design for the passage through water-bearing fracture zones.The study has been carried out in the following five stages: A. Compilation of the relevant data for deformation zone NE-1; B. Problem identification and proposal of technical solutions; C. Identification of hazards to be involved in the tunnel excavation; D. Recommendations and conclusions for further investigations; E. Documentation of the results in a final report. The analyses will be expressed in statistical/probabilistic terms where appropriate. In order to specify the precondition that will be valid for this study, a descriptive model of the water-bearing fracture zone is

  14. Reliability analysis of idealized tunnel support system using probability-based methods with case studies

    NARCIS (Netherlands)

    Gharouni-Nik, M.; Naeimi, M.; Ahadi, S.; Alimoradi, Z.

    2014-01-01

    In order to determine the overall safety of a tunnel support lining, a reliability-based approach is presented in this paper. Support elements in jointed rock tunnels are provided to control the ground movement caused by stress redistribution during the tunnel drive. Main support elements contribute

  15. Cysteine adsorption on the Au(111) surface and the electron transfer in configuration of a scanning tunneling microscope: A quantum-chemical approach

    DEFF Research Database (Denmark)

    Nazmutdinov, R.R.; Manyurov, I.R.; Zinkicheva, T.T.

    2007-01-01

    Adsorption of two forms, molecule and radical, of amino acid L-cysteine (Cys) on the Au-12 cluster that simulates the (111) face of single-crystal gold is studied in the framework of the density functional theory. Effects of solvation of adsorbed Cys particles and lateral interaction in a monolayer...... shape and the orientation of adsorbed Cys particles. Calculation results are compared with fresh in situ submolecular-resolution STM data. Simulated images (with commensurate contributions made by sulfur atom and amino group) built for Cys radical adsorbed in the "on-top" position give best conformance...

  16. Scanning-electron-microscope used in real-time study of friction and wear

    Science.gov (United States)

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

    1975-01-01

    Small friction and wear apparatus built directly into scanning-electron-microscope provides both dynamic observation and microscopic view of wear process. Friction and wear tests conducted using this system have indicated that considerable information can readily be gained.

  17. Study of the tunnelling initiated leakage current through the carbon nanotube embedded gate oxide in metal oxide semiconductor structures

    International Nuclear Information System (INIS)

    Chakraborty, Gargi; Sarkar, C K; Lu, X B; Dai, J Y

    2008-01-01

    The tunnelling currents through the gate dielectric partly embedded with semiconducting single-wall carbon nanotubes in a silicon metal-oxide-semiconductor (MOS) structure have been investigated. The application of the gate voltage to such an MOS device results in the band bending at the interface of the partly embedded oxide dielectric and the surface of the silicon, initiating tunnelling through the gate oxide responsible for the gate leakage current whenever the thickness of the oxide is scaled. A model for silicon MOS structures, where carbon nanotubes are confined in a narrow layer embedded in the gate dielectric, is proposed to investigate the direct and the Fowler-Nordheim (FN) tunnelling currents of such systems. The idea of embedding such elements in the gate oxide is to assess the possibility for charge storage for memory device applications. Comparing the FN tunnelling onset voltage between the pure gate oxide and the gate oxide embedded with carbon nanotubes, it is found that the onset voltage decreases with the introduction of the nanotubes. The direct tunnelling current has also been studied at very low gate bias, for the thin oxide MOS structure which plays an important role in scaling down the MOS transistors. The FN tunnelling current has also been studied with varying nanotube diameter

  18. Study of the tunnelling initiated leakage current through the carbon nanotube embedded gate oxide in metal oxide semiconductor structures.

    Science.gov (United States)

    Chakraborty, Gargi; Sarkar, C K; Lu, X B; Dai, J Y

    2008-06-25

    The tunnelling currents through the gate dielectric partly embedded with semiconducting single-wall carbon nanotubes in a silicon metal-oxide-semiconductor (MOS) structure have been investigated. The application of the gate voltage to such an MOS device results in the band bending at the interface of the partly embedded oxide dielectric and the surface of the silicon, initiating tunnelling through the gate oxide responsible for the gate leakage current whenever the thickness of the oxide is scaled. A model for silicon MOS structures, where carbon nanotubes are confined in a narrow layer embedded in the gate dielectric, is proposed to investigate the direct and the Fowler-Nordheim (FN) tunnelling currents of such systems. The idea of embedding such elements in the gate oxide is to assess the possibility for charge storage for memory device applications. Comparing the FN tunnelling onset voltage between the pure gate oxide and the gate oxide embedded with carbon nanotubes, it is found that the onset voltage decreases with the introduction of the nanotubes. The direct tunnelling current has also been studied at very low gate bias, for the thin oxide MOS structure which plays an important role in scaling down the MOS transistors. The FN tunnelling current has also been studied with varying nanotube diameter.

  19. Dysprosium disilicide nanostructures on silicon(001) studied by scanning tunneling microscopy and transmission electron microscopy

    International Nuclear Information System (INIS)

    Ye Gangfeng; Nogami, Jun; Crimp, Martin A.

    2006-01-01

    The microstructure of self-assembled dysprosium silicide nanostructures on silicon(001) has been studied by scanning tunneling microscopy and transmission electron microscopy. The studies focused on nanostructures that involve multiple atomic layers of the silicide. Cross-sectional high resolution transmission electron microscopy images and fast Fourier transform analysis showed that both hexagonal and orthorhombic/tetragonal silicide phases were present. Both the magnitude and the anisotropy of lattice mismatch between the silicide and the substrate play roles in the morphology and epitaxial growth of the nanostructures formed

  20. Electronic structure and scanning tunnelling microscope images of missing-atom defects on MoS{sub 2} and MoTe{sub 2} surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Caulfield, J.C.; Fisher, A.J. [Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT (United Kingdom)

    1997-05-05

    Missing-atom defects on the transition metal dichalcogenides MoS{sub 2} and MoTe{sub 2} have been studied using the projector augmented-wave method, based on ab initio density functional theory. The presence of the vacancies results in localized electronic states in the surface band gap which can affect the STM image, and on the basis of our results we believe that the hole and trimer defects such as those observed by Fuchs et al could be explained by single-missing-chalcogen and single-missing-metal-atom defects respectively. It is found that the chalcogen vacancy systems behave in a similar way for both MoS{sub 2} and MoTe{sub 2}; however, the system of MoTe{sub 2} with a metal vacancy is discovered to be a Jahn-Teller system, while the equivalent MoS{sub 2} system is not. The effects that this has on the atomic and electronic structure and the STM images are discussed. (author)

  1. Thermoluminescence due to tunneling in nanodosimetric materials: A Monte Carlo study

    Science.gov (United States)

    Pagonis, Vasilis; Truong, Phuc

    2018-02-01

    Thermoluminescence (TL) signals from nanodosimetric materials have been studied extensively during the past twenty years, especially in the area of nanomaterials doped with rare earths. One of the primary effects being studied experimentally have been possible correlations between the nanocrystal size and the shape and magnitude of TL signals. While there is an abundance of experimental studies attempting to establish such correlations, the underlying mechanism is not well understood. This paper is a Monte Carlo simulation study of the effect of nanocrystal size on the TL signals, for materials in which quantum tunneling is the dominant recombination mechanism. TL signals are simulated for a random distribution of electrons and positive ions, by varying the following parameters in the model: the radius of the crystal R, tunneling length a, and the relative concentrations of electrons and ions. The simulations demonstrate that as the radius of the nanocrystals becomes larger, the peaks of the TL glow curves shift towards lower temperatures and changes occur in both peak intensity and peak width. For large crystals with a constant density of positive ions, the TL glow curves reach the analytical limit expected for bulk materials. The commonly used assumption of nearest neighbor interactions is examined within the model, and simulated examples are given in which this assumption breaks down. It is demonstrated that the Monte Carlo method presented in this paper can also be used for linearly modulated infrared stimulated luminescence (LM-IRSL) signals, which are of importance in luminescence dosimetry and luminescence dating applications. New experimental data are presented for Durango apatite, a material which is known to exhibit strong anomalous fading due to tunneling; the experimental data is compared with the model. The relevance of the simulated results for luminescence dosimetry is discussed.

  2. Grain boundary engineering of La{sub 0.7} Sr{sub 0.3} MnO{sub 3} films on silicon substrate: Scanning Tunneling Microscopy-Spectroscopy study

    Energy Technology Data Exchange (ETDEWEB)

    Joshi, Anupama [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411025 (India); Nori, Rajashree [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology (IIT Bombay), Mumbai 400076 (India); Dhobale, Sandip [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411025 (India); Ramgopal Rao, V. [Centre of Excellence in Nanoelectronics, Department of Electrical Engineering, Indian Institute of Technology (IIT Bombay), Mumbai 400076 (India); Kale, S.N., E-mail: sangeetakale2004@gmail.com [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411025 (India); Datar, Suwarna, E-mail: suwarna.datar@gmail.com [Department of Applied Physics, Defence Institute of Advanced Technology (DU), Girinagar, Pune 411025 (India)

    2014-09-01

    We employed a Scanning Tunnelling Microscope (STM) to study the surface topography and spatially resolved local electronic properties like local density of states (LDOS) of nanostructured films of La{sub 0.7} Sr{sub 0.3} MnO{sub 3} (LSMO). The nanostructured thin films of LSMO on silicon substrate were prepared using Pulsed Laser Deposition (PLD) technique. The deposition conditions were tuned to yield two different morphologies; one with uniform columnar closely packed islands and other with larger grain distribution in random fashion. The Scanning Tunnelling Spectroscopy (STS) revealed the extent of variation of density of states (DOS) near the Fermi level. From the spectroscopic features obtained we found the occurrence of phase separation between conducting and semiconducting domains and its possible correlation with the properties of the system. Semiconducting nature was observed at the grain boundaries, which could be extremely promising in futuristic nano-devices.

  3. Correlation of tunnel widening and tunnel positioning with short-term functional outcomes in single-bundle anterior cruciate ligament reconstruction using patellar tendon versus hamstring graft: a prospective study.

    Science.gov (United States)

    Biswal, Udit Kumar; Balaji, Gopisankar; Nema, Sandeep; Poduval, Murali; Menon, Jagdish; Patro, Dilip Kumar

    2016-08-01

    To study the correlation between tunnel widening and tunnel position with short-term functional outcomes post-ACL reconstruction with patellar tendon and hamstring autografts in young adults. A total of 33 patients who underwent ACL reconstruction between October 2013 and February 2015 were included and followed up for 6 months. A standardized surgical technique was used for each graft type. Intra-op arthroscopy findings and drilled tunnel diameters were noted. They were followed up for 3 and 6 months. Radiological assessment was done at 3 and 6 months with clinical score assessment at 6 months. At 6 months, clinical scores were comparable in both groups. Tunnel widening in both femoral and tibial tunnel at 3 and 6 months were significantly higher in STG group (p values <0.05). The rate of widening was higher in 0-3 months and reduced in 3-6 months. There was statistically significant negative correlation between femoral tunnel widening by CT and IKDC score at 6 months (p value 0.049). We found a positive correlation between posterior positioning of femoral tunnel and Lysholm and IKDC scores. The correlation with Lysholm scores was statistically significant (p value 0.046). To conclude, tunnel widening is more with hamstrings graft. Femoral tunnel widening has significant negative correlation with that of IKDC scores at 6 months. Posterior femoral tunnel positioning and Lysholm scores at 6 months had significant correlation.

  4. Imaging of buried phosphorus nanostructures in silicon using scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Oberbeck, Lars [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); TOTAL Marketing Services, New Energies, La Défense 10, 92069 Paris La Défense Cedex (France); Reusch, Thilo C. G.; Hallam, Toby; Simmons, Michelle Y., E-mail: n.curson@ucl.ac.uk, E-mail: michelle.simmons@unsw.edu.au [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); Schofield, Steven R. [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); London Centre for Nanotechnology, UCL, London WC1H 0AH (United Kingdom); Department of Physics and Astronomy, UCL, London WC1E 6BT (United Kingdom); Curson, Neil J., E-mail: n.curson@ucl.ac.uk, E-mail: michelle.simmons@unsw.edu.au [Centre for Quantum Computation and Communication Technology, School of Physics, University of New South Wales, Sydney, New South Wales 2052 (Australia); London Centre for Nanotechnology, UCL, London WC1H 0AH (United Kingdom); Department of Electronic and Electrical Engineering, UCL, London WC1E 7JE (United Kingdom)

    2014-06-23

    We demonstrate the locating and imaging of single phosphorus atoms and phosphorus dopant nanostructures, buried beneath the Si(001) surface using scanning tunneling microscopy. The buried dopant nanostructures have been fabricated in a bottom-up approach using scanning tunneling microscope lithography on Si(001). We find that current imaging tunneling spectroscopy is suited to locate and image buried nanostructures at room temperature and with residual surface roughness present. From these studies, we can place an upper limit on the lateral diffusion during encapsulation with low-temperature Si molecular beam epitaxy.

  5. Imaging of buried phosphorus nanostructures in silicon using scanning tunneling microscopy

    International Nuclear Information System (INIS)

    Oberbeck, Lars; Reusch, Thilo C. G.; Hallam, Toby; Simmons, Michelle Y.; Schofield, Steven R.; Curson, Neil J.

    2014-01-01

    We demonstrate the locating and imaging of single phosphorus atoms and phosphorus dopant nanostructures, buried beneath the Si(001) surface using scanning tunneling microscopy. The buried dopant nanostructures have been fabricated in a bottom-up approach using scanning tunneling microscope lithography on Si(001). We find that current imaging tunneling spectroscopy is suited to locate and image buried nanostructures at room temperature and with residual surface roughness present. From these studies, we can place an upper limit on the lateral diffusion during encapsulation with low-temperature Si molecular beam epitaxy.

  6. Immunoelectron Microscopic Study of Podoplanin Localization in Mouse Salivary Gland Myoepithelium

    Science.gov (United States)

    Hata, Minoru; Amano, Ikuko; Tsuruga, Eichi; Kojima, Hiroshi; Sawa, Yoshihiko

    2010-01-01

    We have recently reported that salivary gland cells express the lymphatic endothelial cell marker podoplanin. The present study was aimed to immunohistochemically investigate the expression of the myoepithelial cell marker α-smooth muscle actin (SMA) on podoplanin-positive cells in mouse parotid and sublingual glands, and to elucidate podoplanin localization in salivary gland myoepithelial cells by immunoelectron microscopic study. The distribution of myoepithelial cells expressing podoplanin and α-SMA was examined by immunofluorescent staining, and the localization of reaction products of anti-podoplanin antibody was investigated by pre-embedded immunoelectron microscopic method. In immunohistochemistry, the surfaces of both the mucous acini terminal portion and ducts were covered by a number of extensive myoepithelial cellular processes expressing podoplanin, and the immunostaining level with anti-podoplanin antibody to myoepithelial cells completely coincided with the immunostaining level with anti-α-SMA antibody. These findings suggest that podoplanin is a salivary gland myoepithelial cell antigen, and that the detection level directly reflects the myoepithelial cell distribution. In immunoelectron microscopic study, a number of reaction products with anti-podoplanin antibody were found at the Golgi apparatus binding to the endoplasmic reticulum in the cytoplasm of myoepithelial cells between sublingual gland acinar cells, and were also found at the myoepithelial cell membrane. These findings suggest that salivary gland myoepithelial cells constantly produce podoplanin and glycosylate at the Golgi apparatus, and transport them to the cell membrane. Podoplanin may be involved in maintaining the homeostasis of myoepithelial cells through its characteristic as a mucin-type transmembrane glycoprotein. PMID:20514295

  7. Near Field and Tunnel Effects Study of Controlled Source Magnetotellurics on the Hallandsåsen Horst; Sweden

    Science.gov (United States)

    Shan, C.; Pedersen, L.

    2012-04-01

    In nearly all studies conducted in Sweden using the EnviroMT controlled source technique, near field effects can be seen at frequencies below 15 kHz. In this study a profile parallel to the Hallandsåsen railway tunnel in southern Sweden crossing the 2D Hallandsåsen horst, the electromagnetic response is further influenced by the conductive armed concrete coating the tunnel walls at a depth of 150 m below the surface. Thus the problem of simulating the electromagnetic response from the 3D structure using a controlled source becomes complicated and inversion results based upon 2D models must be interpreted with care. A synthetic 3D model consisting of two conductive zones crossing the profile and one tunnel parallel to the profile was set up and the responses were calculated using the 3D forward program X3D (Avdeev, 2006) to study both the near field effect and the tunnel effect. The geometry of transmitters and receivers was the same as for the field measurements conducted earlier. Apparent resistivity and phase responses are quite similar to those of the real data in both current modes (parallel and orthogonal to the tunnel). A transitional zone between the near field and far field was seen in the synthetic response with dropping apparent resistivity compared with the plane wave response. This effect is more obvious in parallel mode with the electric current perpendicular to the conductive zones and parallel to the tunnel. When comparing this response to the model response without the tunnel, the differences between the apparent resistivity in the parallel mode show that the conductive tunnel reduces the near field effect. In the perpendicular mode, there is only a small near field effect. The difference between the responses with and without tunnel in the perpendicular mode is very small, indicating that the apparent resistivity is not much influenced by the conductor. The phase in the parallel mode only drops at the stations close to the source, but without

  8. [THE MYCOBIOTA IN STUDYING THE RESISTANCE OF GYPSUM PLASTERBOARD TO MICROSCOPIC FUNGI].

    Science.gov (United States)

    Pysmenna, Yu B; Subbota, A G; Nakonechna, L T

    2015-01-01

    The resistance of two types of gypsum plasterboard: ordinary and water-resistant to microscopic fungi was studied. It was found that under conditions of high relative humidity and direct influence of water at constant temperature (29 ± 2) degrees C all samples of plasterboard were not resistant to fungi. Furthermore, the contaminating mycobiota of uninfected fragments of plasterboard was revealed under these conditions. It was discovered that the test cultures Aspergillus terreus and Trichoderma viride were the most active at the stage of developed mycelium.

  9. Hyaline ring granuloma: a case report with histochemical and polarized microscopic studies.

    Science.gov (United States)

    Lin, S K; Chiang, C P; Ou, S H; Wang, J T; Liu, B Y; Lan, W H

    1993-11-01

    An unusual case of hyaline ring granuloma arising from the connective tissue wall of a residual apical periodontal cyst is reported. Hyaline rings with foreign-body type giant cell inclusions were a significant feature in the histopathologic diagnosis. Histochemical and polarized light microscopic studies suggested that the introduction of foreign material, possibly cellulose, through the postextraction socket into the cystic wall may have caused the granulomatous reaction and formation of the hyaline ring granuloma. The clinical features of this case and 66 previously reported cases, as well as the pathogenesis of the hyaline rings, are discussed.

  10. Microscope basics.

    Science.gov (United States)

    Sluder, Greenfield; Nordberg, Joshua J

    2013-01-01

    This chapter provides information on how microscopes work and discusses some of the microscope issues to be considered in using a video camera on the microscope. There are two types of microscopes in use today for research in cell biology-the older finite tube-length (typically 160mm mechanical tube length) microscopes and the infinity optics microscopes that are now produced. The objective lens forms a magnified, real image of the specimen at a specific distance from the objective known as the intermediate image plane. All objectives are designed to be used with the specimen at a defined distance from the front lens element of the objective (the working distance) so that the image formed is located at a specific location in the microscope. Infinity optics microscopes differ from the finite tube-length microscopes in that the objectives are designed to project the image of the specimen to infinity and do not, on their own, form a real image of the specimen. Three types of objectives are in common use today-plan achromats, plan apochromats, and plan fluorite lenses. The concept of mounting video cameras on the microscope is also presented in the chapter. Copyright © 2003 Elsevier Inc. All rights reserved.

  11. Scanning tunneling microscopy of monoatomic gold chains on vicinal Si(335) surface: experimental and theoretical study

    Energy Technology Data Exchange (ETDEWEB)

    Krawiec, M.; Kwapinski, T.; Jalochowski, M. [Institute of Physics and Nanotechnology Center, M. Curie-Sklodowska University, pl. M. Curie-Sklodowskiej 1, 20-031 Lublin (Poland)

    2005-02-01

    We study electronic and topographic properties of the Si(335) surface, containing Au wires parallel to the steps. We use scanning tunneling microscopy (STM) supplemented by reflection of high energy electron diffraction (RHEED) technique. The STM data show the space and voltage dependent oscillations of the distance between STM tip and the surface which can be explained within one band tight binding Hubbard model. We calculate the STM current using nonequilibrium Keldysh Green function formalism. (copyright 2005 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  12. An apparatus for studying spallation neutrons in the Aberdeen Tunnel laboratory

    Energy Technology Data Exchange (ETDEWEB)

    Blyth, S.C. [Department of Electro-Optical Engineering, National United University, Miao-Li, Taiwan (China); Chan, Y.L.; Chen, X.C.; Chu, M.C. [Department of Physics, Chinese University of Hong Kong, Hong Kong (China); Hahn, R.L. [Chemistry Department, Brookhaven National Laboratory, Upton, NY 11973 (United States); Ho, T.H.; Hsiung, Y.B. [Department of Physics, National Taiwan University, Taipei, Taiwan (China); Hu, B.Z. [Institute of Physics, National Chiao-Tung University, Hsinchu, Taiwan (China); Kwan, K.K.; Kwok, M.W. [Department of Physics, Chinese University of Hong Kong, Hong Kong (China); Kwok, T., E-mail: goodtalent@gmail.com [Department of Physics, University of Hong Kong, Hong Kong (China); Lau, Y.P.; Lee, K.P.; Leung, J.K.C.; Leung, K.Y. [Department of Physics, University of Hong Kong, Hong Kong (China); Lin, G.L. [Institute of Physics, National Chiao-Tung University, Hsinchu, Taiwan (China); Lin, Y.C. [Department of Physics, Chinese University of Hong Kong, Hong Kong (China); Luk, K.B. [Department of Physics, University of California at Berkeley, Berkeley, CA 94720 (United States); Luk, W.H. [Department of Physics, Chinese University of Hong Kong, Hong Kong (China); Ngai, H.Y. [Department of Physics, University of Hong Kong, Hong Kong (China); and others

    2013-09-21

    In this paper, we describe the design, construction and performance of an apparatus installed in the Aberdeen Tunnel laboratory in Hong Kong for studying spallation neutrons induced by cosmic-ray muons under a vertical rock overburden of 611 m water equivalent (m.w.e.). The apparatus comprises six horizontal layers of plastic-scintillator hodoscopes for determining the direction and position of the incident cosmic-ray muons. Sandwiched between the hodoscope planes is a neutron detector filled with 650 kg of liquid scintillator doped with about 0.06% of Gadolinium by weight for improving the efficiency of detecting the spallation neutrons. Performance of the apparatus is also presented.

  13. Rotational barriers in ammonium hexachlorometallates as studied by NMR, tunneling spectroscopy and ab initio calculations

    DEFF Research Database (Denmark)

    Birczynski, A.; Lalowicz, Z.T.; Lodziana, Zbigniew

    2004-01-01

    potential barrier. It was also observed that TF correlates directly with the lattice constant of a particular compound. This correlation is explained by density-functional theory (DFT). The size of the unit cell is governed by the nature of metal-chlorine interaction, with respect to which the studied...... structure explain observed variation of the tunnelling frequencies for NH4+. The theory provides also M-Cl distances and barriers for C-2 and C-3 rotations of ammonium ions in respective compounds, which show good agreement with experimental values. (C) 2004 Elsevier B.V. All rights reserved....

  14. Experimental study of macroscopic quantum tunnelling in Bi2212 intrinsic Josephson junctions

    International Nuclear Information System (INIS)

    Matsumoto, Tetsuro; Kashiwaya, Hiromi; Shibata, Hajime; Kashiwaya, Satoshi; Kawabata, Shiro; Eisaki, Hiroshi; Yoshida, Yoshiyuki; Tanaka, Yukio

    2007-01-01

    The quantum dynamics of Bi 2 Sr 2 CaCu 2 O 8+δ intrinsic Josephson junctions (IJJs) is studied based on escape rate measurements. The saturations observed in the escape temperature and in the width of the switching current below 0.5 K (= T * ) indicate the transition of the switching mechanism from thermal activation to macroscopic quantum tunnelling. It is shown that the switching properties are consistently explained in terms of the underdamped Josephson junction with a quality factor of 70 ± 20 in spite of possible damping due to the nodal quasiparticles of d-wave superconductivity. The present result gives the upper limit of the damping of IJJs

  15. Assessing the Penetrating Abilities of Experimental Preparation with Dental Infiltrant Features Using Optical Microscope: Preliminary Study.

    Science.gov (United States)

    Skucha-Nowak, Małgorzata; Machorowska-Pieniążek, Agnieszka; Tanasiewicz, Marta

    2016-01-01

    The aim of the infiltration technique is to penetrate demineralized enamel with a low viscosity resin. Icon® (DMG) is the first ever and so far the only dental infiltrant. Bacteriostaticity is one of the properties that should be inherent in dental infiltrants, but Icon lacks this feature. The aim of the preliminary study was to properly choose a dye which would allow us to assess the penetrating abilities of our own, experimental preparation with features of a dental infiltrant with bacteriostatic properties and to compare using an optical microscope the depth of infiltration of the designed experimental preparation with the infiltrant available on the market. The preparation is supposed to infiltrate decalcified human enamel and be assessed with an optical microscope. Eosin, neutral fuchsine and methylene blue were added to experimental preparation with dental infiltrant features and to Icon® (DMG) in order to assess the depth of penetration of the experimental solution into the decalcified layers of enamel. The experimental solution mixes well with eosin, neutral fuchsine, and methylene blue. During the preliminary study, the authors concluded that the experimental solution mixes well with methylene blue, neutral fuchsine, and eosin. An addition of eosin to a preparation which infiltrates inner, demineralized enamel layers, facilitates the assessment of such a preparation with an optical microscope. A designed experimental solution with the main ingredients, i.e., 2-hydroxyethyl methacrylate (HEMA) and tetraethylene glycol dimethacrylate (TEGDMA) with a ratio of 75% to 25% penetrates the demineralized (decalcified) inner parts of the enamel and polymerizes when exposed to light. In order to assess the infiltration of the experimental solution into the demineralized enamel layers, it is required to improve the measurement techniques that utilize optical microscopy.

  16. Microscopic study of rock for estimating long-term behavior. Research document

    International Nuclear Information System (INIS)

    Ichikawa, Yasuaki

    2003-02-01

    Micro-structure of rock plays an essential role for their long-term behavior. For elucidating long-term characteristics of granite we here present the followings: 1) Conformal Lase Scanning Microscope (LSM) observation of configuration of a joint in granite, its Fourier analysis and the change under uniaxial stress condition, 2) characterization of the mechanism of microcrack initiation and propagation observed by stereoscopic microscope under uniaxial/triaxial compression and relaxation tests, 3) observation of microcrack initiation and propagation by LSM under uniaxial compression, and 4) a study of strong discontinuity analysis included in the homogenization theory to predict the long-term behavior of micro/macro-level stress for granite. Rock image processing and analysis become a fundamental procedure to determine rock surface discontinuities. In Chapter 2 LSM that can acquire three-dimensional images is introduced to observe the roughness of discontinuity in a rock specimen. Then, discontinuities appeared on circular sections are identified by LSM and characterized by a Discrete Fourier Transform (DFT) analysis. The change of discontinuities is observed under applying stress. Microcrack generation and propagation play an essential role to predict the long-term behavior of rock. In Chapter 3 a progressive development of cracking in granite is revealed by using stereoscopic microscope under water-saturated triaxial compression condition. Next by using LSM observe the procedure of micro-cracking under uniaxial compression condition. Obviously the micro-crack initiation and propagation controls the time-dependent behavior of granite. We have analysed the behavior by a viscoelastic theory applied in homogenization method. However since it is difficult to determine the inter-granular properties of constituent crystals and to represent the stress-dependent nonlinear characteristics by this method, we study a strong discontinuity analysis included in the

  17. The Gray Institute open microscopes applied to radiobiology and protein interaction studies

    Science.gov (United States)

    Barber, P. R.; Tullis, I. D. C.; Rowley, M. I.; Martins, C. D.; Weitsman, G.; Lawler, K.; Coffey, M.; Woodman, N.; Gillett, C. E.; Ng, T.; Vojnovic, B.

    2014-03-01

    We describe an 'open' design methodology for wide-field fluorescence, confocal and fluorescence lifetime imaging microscopy (FLIM), and how the resulting microscopes are being applied to radiation biology and protein activity studies in cells and human tissue biopsies. The design approach allows easy expansion as it moves away from the use of a monolithic microscope body to small, commercial off-the-shelf and custom made modular components. Details have been made available under an open license for non-commercial use at http://users.ox.ac.uk/~atdgroup. Two radiobiology 'end-stations' have been constructed which enable fast radiation targeting and imaging of biological material opening up completely novel studies, where the consequences of ionising radiation (signaling and protein recruitment) can be studied in situ, at short times following irradiation. One is located at Surrey University, UK, where radiation is a highly focused in beam (e.g. protons, helium or higher mass ions). The second is installed at the Gray Institute linear accelerator facility, Oxford University, which uses sub-microsecond pulses of 6 MeV electrons. FLIM capabilities have enhanced the study of protein-protein interactions in cells and tissues via Förster Resonance Energy Transfer (FRET). Extracting FRET signals from breast cancer tissue is challenging because of endogenous and fixation fluorescence; we are investigating novel techniques to measure this robustly. Information on specific protein interactions from large numbers of patient tumors will reveal prognostic and diagnostic information.

  18. Microwave Microscope

    Data.gov (United States)

    Federal Laboratory Consortium — FUNCTION: Makes ultra-high-resolution field measurements. The Microwave Microscope (MWM) has been used in support of several NRL experimental programs involving sea...

  19. A vegetation modeling concept for Building and Environmental Aerodynamics wind tunnel tests and its application in pollutant dispersion studies

    International Nuclear Information System (INIS)

    Gromke, Christof

    2011-01-01

    A new vegetation modeling concept for Building and Environmental Aerodynamics wind tunnel investigations was developed. The modeling concept is based on fluid dynamical similarity aspects and allows the small-scale modeling of various kinds of vegetation, e.g. field crops, shrubs, hedges, single trees and forest stands. The applicability of the modeling concept was validated in wind tunnel pollutant dispersion studies. Avenue trees in urban street canyons were modeled and their implications on traffic pollutant dispersion were investigated. The dispersion experiments proved the modeling concept to be practicable for wind tunnel studies and suggested to provide reliable concentration results. Unfavorable effects of trees on pollutant dispersion and natural ventilation in street canyons were revealed. Increased traffic pollutant concentrations were found in comparison to the tree-free reference case. - Highlights: → A concept for aerodynamic modelling of vegetation in small scale wind tunnel studies is presented. → The concept was applied to study pollutant dispersion in urban street canyons with avenue tress. → The wind tunnel studies show that modelling the aerodynamic effects of vegetation is important. → Avenue trees give rise to increased pollutant concentrations in urban street canyons. - Avenue trees in urban street canyons affect the pollutant dispersion and result in increased traffic exhaust concentrations.

  20. A scanning electron microscopic study of the dysplastic epithelia adjacent to oral squamous cell carcinoma.

    Science.gov (United States)

    Worawongvasu, Ratthapong

    2007-01-01

    By light microscopy, the dysplastic oral epithelia due to the neoplastic processes are similar to epithelial changes due to the inflammatory processes. Scanning electron microscopy may elucidate the different surface changes between the two. The aim of this study was to examine the surface appearances of the dysplastic oral epithelia adjacent to oral squamous cell carcinoma to see if there are any surface changes. A total of 2 specimens, one specimen from each patient with oral squamous cell carcinoma, were used for this study. Each specimen was divided in two. One half was prepared for light microscopy and the other half was prepared for scanning electron microscopy. Light microscopically, the epithelia showed mild dysplasia. By scanning electron microscopy, the keratinized cells showed irregular microridges surrounding pits, which were variable and irregular in size and shape, and the nonkeratinized cells showed parallel microridges with irregularly widened intervals between each microridge. Irregular, broad, and partly swollen microridges and irregular short, stubby surface projections were also seen. The oral epithelia adjacent to oral squamous cell carcinoma showed mild dysplasia light microscopically but appeared abnormal by scanning electron microscopy. The abnormal epithelial cells showed pleomorphism, irregular and disoriented microridges, and abnormal surface microstructures.

  1. RAM analysis of earth pressure balance tunnel boring machines: A case study

    Directory of Open Access Journals (Sweden)

    Hasel Amini Khoshalan

    2015-12-01

    Full Text Available Earth pressure balance tunnel boring machines (EPB-TBMs are favorably applied in urban tunneling projects. Despite their numerous advantages, considerable delays and high maintenance cost are the main disadvantages these machines suffer from. Reliability, availability, and maintainability (RAM analysis is a practical technique that uses failure and repair dataset obtained over a reasonable time for dealing with proper machine operation, maintenance scheduling, cost control, and improving the availability and performance of such machines. In the present study, a database of failures and repairs of an EBP-TBM was collected in line 1 of Tabriz subway project over a 26-month interval of machine operation. In order to model the reliability of the TBM, this machine was divided into five distinct subsystems including mechanical, electrical, hydraulic, pneumatic, and water systems in a series configuration. According to trend and serial correlation tests, the renewal processes were applied, for analysis of all subsystems. After calculating the reliability and maintainability functions for all subsystems, it was revealed that the mechanical subsystem with the highest failure frequency has the lowest reliability and maintainability. Similarly, estimating the availability of all subsystems indicated that the mechanical subsystem has a relatively low availability level of 52.6%, while other subsystems have acceptable availability level of 97%. Finally, the overall availability of studied machine was calculated as 48.3%.

  2. Fabrication of Gate-tunable Graphene Devices for Scanning Tunneling Microscopy Studies with Coulomb Impurities.

    Science.gov (United States)

    Jung, Han Sae; Tsai, Hsin-Zon; Wong, Dillon; Germany, Chad; Kahn, Salman; Kim, Youngkyou; Aikawa, Andrew S; Desai, Dhruv K; Rodgers, Griffin F; Bradley, Aaron J; Velasco, Jairo; Watanabe, Kenji; Taniguchi, Takashi; Wang, Feng; Zettl, Alex; Crommie, Michael F

    2015-07-24

    Owing to its relativistic low-energy charge carriers, the interaction between graphene and various impurities leads to a wealth of new physics and degrees of freedom to control electronic devices. In particular, the behavior of graphene's charge carriers in response to potentials from charged Coulomb impurities is predicted to differ significantly from that of most materials. Scanning tunneling microscopy (STM) and scanning tunneling spectroscopy (STS) can provide detailed information on both the spatial and energy dependence of graphene's electronic structure in the presence of a charged impurity. The design of a hybrid impurity-graphene device, fabricated using controlled deposition of impurities onto a back-gated graphene surface, has enabled several novel methods for controllably tuning graphene's electronic properties. Electrostatic gating enables control of the charge carrier density in graphene and the ability to reversibly tune the charge and/or molecular states of an impurity. This paper outlines the process of fabricating a gate-tunable graphene device decorated with individual Coulomb impurities for combined STM/STS studies. These studies provide valuable insights into the underlying physics, as well as signposts for designing hybrid graphene devices.

  3. Cavitation studies on axi-symmetric underwater body with pumpjet propulsor in cavitation tunnel

    Directory of Open Access Journals (Sweden)

    Ch. Suryanarayana

    2010-12-01

    Full Text Available A pumpjet propulsor (PJP was designed for an underwater body (UWB with axi-symmetric configuration. Its performance was predicted through CFD study and models were manufactured. The propulsor design was evaluated for its propulsion characteristics through model tests conducted in a Wind Tunnel (WT. In the concluding part of the study, evaluation of the cavitation performance of the pumpjet was undertaken in a cavitation tunnel (CT. In order to assess the cavitation free operation speeds and depths of the body, cavitation tests of the PJP were carried out in behind condition to determine the inception cavitation numbers for rotor, stator and cowl. The model test results obtained were corrected for full scale Reynolds number and subsequently analyzed for cavitation inception speeds at different operating depths. From model tests it was also found that the cavitation inception of the rotor takes place on the tip face side at higher advance ratios and cavitation shifts towards the suction side as the RPS increases whereas the stator and cowl are free from cavitation.

  4. Scanning Tunnelling Spectroscopic Studies of Dirac Fermions in Graphene and Topological Insulators

    Directory of Open Access Journals (Sweden)

    wang K.-L.

    2012-03-01

    Full Text Available We report novel properties derived from scanning tunnelling spectroscopic (STS studies of Dirac fermions in graphene and the surface state (SS of a strong topological insulator (STI, Bi2Se3. For mono-layer graphene grown on Cu by chemical vapour deposition (CVD, strain-induced scalar and gauge potentials are manifested by the charging effects and the tunnelling conductance peaks at quantized energies, respectively. Additionally, spontaneous time-reversal symmetry breaking is evidenced by the alternating anti-localization and localization spectra associated with the zero-mode of two sublattices while global time-reversal symmetry is preserved under the presence of pseudo-magnetic fields. For Bi2Se3 epitaxial films grown on Si(111 by molecular beam epitaxy (MBE, spatially localized unitary impurity resonances with sensitive dependence on the energy difference between the Fermi level and the Dirac point are observed for samples thicker than 6 quintuple layers (QL. These findings are characteristic of the SS of a STI and are direct manifestation of strong topological protection against impurities. For samples thinner than 6-QL, STS studies reveal the openup of an energy gap in the SS due to overlaps of wave functions between the surface and interface layers. Additionally, spin-preserving quasiparticle interference wave-vectors are observed, which are consistent with the Rashba-like spin-orbit splitting.

  5. Experimental and Simulation Studies of Hydrodynamic Tunneling of Ultra-Relativistic Protons

    CERN Document Server

    Burkart, Florian; Schmidt, Ruediger; Shutov, Alexander; Tahir, Naeem; Wollmann, Daniel; Zerlauth, Markus

    2015-01-01

    The expected damage due to the release of the full LHC beam energy at a single aperture bottleneck has been studied. These studies have shown that the range of the 7 TeV LHC proton beam is significantly extended compared to that of a single proton due to hydrodynamic tunneling effect. For instance, it was evaluated that the protons and their showers will penetrate up to a length of 25 m in solid carbon compared to a static range of around 3 m. To check the validity of these simulations, beam- target heating experiments using the 440 GeV proton beam generated by the SPS were performed at the HiRadMat test facility at CERN. Solid copper targets were facially irradiated by the beam and measurements confirmed hydrodynamic tunneling of the protons and their showers. Simulations have been done by running the energy deposition code FLUKA and the 2D hydrodynamic code, BIG2, iteratively. Very good agreement has been found between the simulations and the experimental results providing confidence in the validity of the ...

  6. Further light microscopic studies on morphology and development of Pneumocystis carinii.

    Science.gov (United States)

    Yoshida, Y; Shiota, T; Yamada, M; Matsumoto, Y

    1981-01-01

    In order to add more advance in light microscopic investigation of P. carinii, phase contrast microscopy partly followed by wet giemsa stain and semiultrathin section of the lungs embedded in JB-4 plastic were studied. In phase contrast microscopy, small and large sized trophozoites of P. carinii were clearly recognized. Although movement of trophozoite was not found, rhythmic movement of intracystic bodies with filopodia was often seen in mature cyst. Those living organisms were then directly stained with Giemsa by infiltrating under the coverglass. Thus the organism could be investigated both in unstained and stained conditions. It is noticed with interest that 8 intracystic bodies seem to fill up the cavity of cyst when cell division is completed, then they liberate and become independent into spherical bodies, followed by banana-shaped or amoeboid forms with motility. An emphasis was done that semiultrathin section made from JB-4 plastic embedded lungs was quite useful for investigation of P. carinii infection. Several sizes of mononuclear thin-walked trophozoites, mature and immature cysts, and empty cysts were more clearly distinguished than any other light microscopical method ever reported.

  7. Spin microscope based on optically detected magnetic resonance

    Science.gov (United States)

    Berman, Gennady P.; Chernobrod, Boris M.

    2007-12-11

    The invention relates to scanning magnetic microscope which has a photoluminescent nanoprobe implanted in the tip apex of an atomic force microscope (AFM), a scanning tunneling microscope (STM) or a near-field scanning optical microscope (NSOM) and exhibits optically detected magnetic resonance (ODMR) in the vicinity of unpaired electron spins or nuclear magnetic moments in the sample material. The described spin microscope has demonstrated nanoscale lateral resolution and single spin sensitivity for the AFM and STM embodiments.

  8. A tunnelling study on polymer/1T-LixTaS2 layered nanocomposites

    International Nuclear Information System (INIS)

    Enomoto, Hiroyuki; Takai, Hiroyuki; Ozaki, Hajime; Lerner, Michael M

    2004-01-01

    Electronic structures near the Fermi level of polymer/1T-Li x TaS 2 layered nanocomposites have been studied by tunnelling spectroscopy. Polymer/1T-Li x TaS 2 layered nanocomposites were synthesized by using the exfoliation-adsorption technique. Single crystals of 1T-TaS 2 were used as host materials. Poly(ethylene oxide) (PEO) and poly(ethylenimine) (PEI) with different molecular weights were adopted as guest intercalants. Powder x-ray diffraction patterns showed that all samples of the polymer/1T-Li x TaS 2 layered nanocomposites contain organic polymer between all individual 1T-TaS 2 sheets. Although 1T-TaS 2 single crystal is well known to show quite unique temperature dependences of the resistivity due to the charge density wave (CDW), the resistivities of all polymer/1T-Li x TaS 2 nanocomposites showed semiconductor-like temperature dependences. The tunnelling spectra of polymer/1T-Li x TaS 2 nanocomposites revealed that the CDW gap disappears in the density of states near the Fermi level of polymer/1T-Li x TaS 2 nanocomposites and their electronic structures show a metallic behaviour

  9. Study on the snow drifting modelling criteria in boundary layer wind tunnels

    Directory of Open Access Journals (Sweden)

    Georgeta BĂETU

    2014-07-01

    Full Text Available The paper presents a study on modelling the wind drifting of the snow deposited on the flat roofs of buildings in wind tunnel. The physical model of snow drifting in wind tunnel simulating the urban exposure to wind action is not frequently reported in literature, but is justified by the serious damages under accidental important snow falls combined with strong wind actions on the roofs of various buildings. A uniform layer of snow deposited on the flat roof was exposed to wind action in order to obtain the drifting. The parameters involved in the modelling at reduced scale, with particles of glass beads, of the phenomenon of transportation of the snow from the roof were analysed, particularly the roughness length and the friction wind speed. A numerical simulation in ANSYS CFX program was developed in parallel, by which a more accurate visualization of the particularities of the wind flow over the roof was possible, in the specific areas where the phenomenon of snow transportation was more susceptible to occur. Modified roughness length and friction wind speed were determined through methods used in the literature, an attempt being made in this work to analyse the factors that influence their values.

  10. Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

    Science.gov (United States)

    Hudişteanu, Sebastian Valeriu; Popovici, Cătălin George; Cherecheş, Nelu-Cristian

    2018-02-01

    The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30). The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF) and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

  11. Wind tunnel study of natural ventilation of building integrated photovoltaics double skin façade

    Directory of Open Access Journals (Sweden)

    Hudişteanu Sebastian Valeriu

    2018-01-01

    Full Text Available The paper presents a wind tunnel experimental analysis of a small-scale building model (1:30. The objective of the study is to determine the wind influence on the ventilation of a double skin façade channel (DSF and the cooling effect over integrated photovoltaic panels. The tests were achieved by conceiving and implementation of an experimental program using a wind tunnel with atmospheric boundary layer. The effect of the wind over the ventilation of the horizontal channels of double skin façades is evaluated for different incident velocities. The results are generalized for the average steady state values of the velocities analysed. The experimental results put in evidence the correlation between the reference wind velocity and the dynamics of the air movement inside the double skin façade. These values are used to determine the convective heat transfer and the cooling effect of the air streams inside the channel upon the integrated photovoltaic panels. The decrease of the photovoltaic panels temperature determines a raise of 11% in efficiency and power generated.

  12. Microscopic Study of 5083-H321 Aluminium Alloy Under Fretting Fatigue Condition

    International Nuclear Information System (INIS)

    Eslamian, S; Sahari, B B; Ali, Aidy; Mahdi, El-Sadiq; Hamouda, A M

    2011-01-01

    Fretting occurs where there is small amplitude oscillating motion between solid surfaces in contact. With even small loads or prolonged operation, fretting may lead to crack initiation followed by fretting fatigue. Its effect on fatigue is to speed up the nucleation of fatigue surface cracks and it can be extremely damaging. Fretting fatigue is a critical concern in aircraft structures and a widespread problem in naval structural components and is often the root cause of fatigue crack nucleation in machine components. In this investigation, fretting fatigue study is carried out using 5083-H321 marine/ aerospace aluminium alloy. The test rig and the experiments were designed with an emphasis to study the crack initiation behaviour in the fretted region using scanning electron microscope (SEM). Fretting damage and its relationship to the fretting fatigue life are presented and discussed.

  13. Microscopic study of 5083-H321 Aluminium alloy under fretting fatigue condition

    International Nuclear Information System (INIS)

    Eslamian, S.; Sahari, B.B.; Aidy Ali; El-Sadiq, M.; Hamouda, A.M.

    2009-01-01

    Full text: Fretting occurs where there is small amplitude oscillating motion between solid surfaces in contact. With even small loads or prolonged operation, fretting may lead to crack initiation followed by fretting fatigue. Its effect on fatigue is to speed up the nucleation of fatigue surface cracks and it can be extremely damaging. Fretting fatigue is a critical concern in aircraft structures and a widespread problem in naval structural components and is often the root cause of fatigue crack nucleation in machine components. In this investigation, fretting fatigue study is carried out using 5083-H321 marine/ aerospace aluminium alloy. The test rig and the experiments were designed with an emphasis to study the crack initiation behaviour in the fretted region using scanning electron microscope (SEM). The damages produced by fretting and its relationship to the fretting fatigue life are discussed in the paper in some depth. (author)

  14. Microscopic Study of 5083-H321 Aluminium Alloy Under Fretting Fatigue Condition

    Energy Technology Data Exchange (ETDEWEB)

    Eslamian, S; Sahari, B B [Institute Advanced Technology, Universiti Putra Malaysia 43400 Serdang, Selangor (Malaysia); Ali, Aidy [Department of Mechanical and Manufacturing Engineering Faculty of Engineering, Universiti Putra Malaysia 43400 Serdang, Selangor (Malaysia); Mahdi, El-Sadiq; Hamouda, A M, E-mail: saeed.eslamian@gmail.com [Mechanical and Industrial Engineering Department, College of Engineering, Qatar University 2713 Doha (Qatar)

    2011-02-15

    Fretting occurs where there is small amplitude oscillating motion between solid surfaces in contact. With even small loads or prolonged operation, fretting may lead to crack initiation followed by fretting fatigue. Its effect on fatigue is to speed up the nucleation of fatigue surface cracks and it can be extremely damaging. Fretting fatigue is a critical concern in aircraft structures and a widespread problem in naval structural components and is often the root cause of fatigue crack nucleation in machine components. In this investigation, fretting fatigue study is carried out using 5083-H321 marine/ aerospace aluminium alloy. The test rig and the experiments were designed with an emphasis to study the crack initiation behaviour in the fretted region using scanning electron microscope (SEM). Fretting damage and its relationship to the fretting fatigue life are presented and discussed.

  15. Irradiation-related amorphization and crystallization: In situ transmission electron microscope studies

    International Nuclear Information System (INIS)

    Allen, C.W.

    1994-01-01

    Interfacing an ion accelerator to a transmission electron microscope (TEM) allows the analytical functions of TEM imaging and diffraction to be employed during ion-irradiation effects studies. At present there are twelve such installations in Japan, one in France and one in the US. This paper treats several aspects of in situ studies involving electron and ion beam induced and enhanced phase transformations and presents results of several in situ experiments to illustrate the dynamics of this approach in the materials science of irradiation effects. The paper describes the ion- and electron-induced amorphization of CuTi; the ion-irradiation-enhanced transformation of TiCr 2 ; and the ion- and electron-irradiation-enhanced crystallization of CoSi 2

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

    Directory of Open Access Journals (Sweden)

    Aris F. Pourlis

    2013-01-01

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

  17. A flexible microrobotic platform for handling microscale specimens of fibrous materials for microscopic studies.

    Science.gov (United States)

    Saketi, P; Von Essen, M; Mikczinski, M; Heinemann, S; Fatikow, S; Kallio, P

    2012-11-01

    One of the most challenging issues faced in handling specimens for microscopy, is avoiding artefacts and structural changes in the samples caused by human errors. In addition, specimen handling is a laborious and time-consuming task and requires skilful and experienced personnel. This paper introduces a flexible microrobotic platform for the handling of microscale specimens of fibrous materials for various microscopic studies such as scanning electron microscopy and nanotomography. The platform is capable of handling various fibres with diameters ranging from 10 to 1000 μm and lengths of 100 μm-15 mm, and mounting them on different types of specimen holders without damaging them. This tele-operated microrobotic platform minimizes human interaction with the samples, which is one of the main sources contributory to introducing artefacts into the specimens. The platform also grants a higher throughput and an improved success rate of specimen handling, when compared to the manual processes. The operator does not need extensive experience of microscale manipulation and only a short training period is sufficient to operate the platform. The requirement of easy configurability for various samples and sample holders is typical in the research and development of materials in this field. Therefore, one of the main criteria for the design of the microrobotic platform was the ability to adapt the platform to different specimen handling methods required for microscopic studies. To demonstrate this, three experiments are carried out using the microrobotic platform. In the first experiment, individual paper fibres are mounted successfully on scanning electron microscopy specimen holders for the in situ scanning electron microscopy diagonal compression test of paper fibres. The performance of the microrobotic platform is compared with a skilled laboratory worker performing the same experiment. In the second experiment, a strand of human hair and an individual paper fibre bond

  18. Uptake and processing of [3H]retinoids in rat liver studied by electron microscopic autoradiography

    International Nuclear Information System (INIS)

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

    1988-01-01

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

  19. A vegetation modeling concept for Building and Environmental Aerodynamics wind tunnel tests and its application in pollutant dispersion studies.

    Science.gov (United States)

    Gromke, Christof

    2011-01-01

    A new vegetation modeling concept for Building and Environmental Aerodynamics wind tunnel investigations was developed. The modeling concept is based on fluid dynamical similarity aspects and allows the small-scale modeling of various kinds of vegetation, e.g. field crops, shrubs, hedges, single trees and forest stands. The applicability of the modeling concept was validated in wind tunnel pollutant dispersion studies. Avenue trees in urban street canyons were modeled and their implications on traffic pollutant dispersion were investigated. The dispersion experiments proved the modeling concept to be practicable for wind tunnel studies and suggested to provide reliable concentration results. Unfavorable effects of trees on pollutant dispersion and natural ventilation in street canyons were revealed. Increased traffic pollutant concentrations were found in comparison to the tree-free reference case. Copyright © 2010 Elsevier Ltd. All rights reserved.

  20. Wind Tunnel Design Studies and Technical Evaluation of Advanced Cargo Aircraft Concepts

    Science.gov (United States)

    Rao, D. M.

    1976-01-01

    In support of aerodynamic studies relating to the design and performance prediction of the National Transonic Facility, the following main tasks were accomplished: (1) estimation of aerodynamic losses of the tunnel circuits, (2) refinement of the high-speed diffuser loss prediction method utilizing experimental data generated for the purpose; (3) model studies of flow in the second-turn and measurements of the fan inlet distortion and overall pressure loss; (4) development of a shortened fan nacelle configuration of improved aerodynamic performance; and (5) evolution through model studies of an efficient rapid-diffuser system as the key to a circuit-modification proposal to reduce volume and minimize liquid-nitrogen consumption, at the same time saving on the shell cost.

  1. Morphological differences between normal and cancerous mammalian cells via multitechnique microscopic studies

    Science.gov (United States)

    Saab, Marie-Belle; Estephan, Elias; Martin, Marta; Bec, Nicole; Larroque, Christian; Cloître, Thierry; Cuisinier, Frédéric; Gergely, Csilla

    2010-04-01

    Despite of the recent year's important advances in breast cancer biology, there is a continuous demand for new microscopic studies able to provide complementary information on cell shape that is an essential feature of the tumour cells affecting their proliferation and spreading. Understanding the relationship between cell shape and cellular function is important for regulation of cell phenotype modification in particular during cancerogenesis. Utilizing a multitechnique approach, we have investigated the morphological differences of normal human mammalian epithelial cells (HMEC) and cancerous breast epithelial cells (MCF7) cells, both mammalian epithelial cells, but from the same cell type, allowing us to compare them. The goal of our investigation was to combine information on morphological properties of these cells provided by imaging techniques like atomic force microscopy (AFM), brightfield microscopy with in-depth images of microtubules via the multiphoton microscopy (MPM). Cells morphology studies for both cells' types were first carried out using the contact mode AFM which has gained great potential for studying biological systems. Brightfield optical imaging was operated in correlation with the AFM measurements. Topography analyses were performed for living cells as well as fixed ones for both MCF7 and HMEC 184 A1 cells. Living cancerous cells are much softer than normal ones, smaller in shape, and more difficult to manipulate. Photonic responses of fixed cells have been then evaluated by the multiphoton microscopy. Due to light's good penetration depth (IR excitation) in biological samples, MPM has already proved to be a reliable and powerful tool in medical and biological deep tissue imaging. Moreover, MPM provides useful three-dimensional information on the structural and optical properties of the specimen due to its intrinsic optical sectioning resolution. Combination of these microscopic techniques allows us to correlate external cell morphology, with

  2. Craniovertebral junction 360°: A combined microscopic and endoscopic anatomical study

    Directory of Open Access Journals (Sweden)

    Sukhdeep Singh Jhawar

    2016-01-01

    Conclusion: With advances in endoscopic and microscopic techniques, access to lesions and bony anomalies around CVJ is becoming easier and straightforward. A combination of microscopic and endoscopic techniques is more useful to understand this anatomy and may aid in the development of future combined approaches.

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

    Science.gov (United States)

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

    2015-01-01

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

  4. Scanning Electron Microscopic Studies of Microwave Sintered Al-SiC Nanocomposites and Their Properties

    Directory of Open Access Journals (Sweden)

    M. A. Himyan

    2018-01-01

    Full Text Available Al-metal matrix composites (AMMCs reinforced with diverse volume fraction of SiC nanoparticles were synthesized using microwave sintering process. The effects of the reinforcing SiC particles on physical, microstructure, mechanical, and electrical properties were studied. The phase, microstructural, and surface analyses of the composites were systematically conducted using X-ray diffraction (XRD, scanning electron microscope (SEM, and surface profilometer techniques, respectively. The microstructural examination revealed the homogeneous distribution of SiC particles in the Al matrix. Microhardness and compressive strength of nanocomposites were found to be increasing with the increasing volume fraction of SiC particles. Electrical conductivity of the nanocomposites decreases with increasing the SiC content.

  5. [Comparative study on macroscopic and microscopic identification of Celastrus aculeatus and Kadsura heteroclite].

    Science.gov (United States)

    Zhang, Qin; Chen, Xing-xing; Zhang, Hong-wei; Ma, Ji; Tong, Li; Mo, Zhi-xian

    2012-05-01

    To compare and identify Celastrus aculeatus and Kadsura heteroclita with pharmacognosy methods for analyzing the quality of the crude drug. Pharmacognosy study on Celastrus aculeatus and Kadsura heteroclite was carried out through plant identification, crude drug identification and microscopic characteristics identification. The characteristics of Celastrus aculeatus and Kadsura heteroclite were compared. There were significant differences between Celastrus aculeatus and Kadsura heteroclite in appearance of cork, attachments on internal surface of cork,shape of leave edge, number of lateral vein, type of stoma and vessel, and the crystals, the stone cells and the fibers in the same part of both drugs. The pharmacognosy characteristics of both crude drugs can be used for identification and quality control on Celastrus aculeatus and Kadsura heteroclite.

  6. Electron-microscopic and autoradiographic study of bronchioalveolar lavage cells in nonspecific inflammation of the lungs

    International Nuclear Information System (INIS)

    Nepomnyashchikh, G.I.; Efremov, V.N.; Nepomnyashchikh, L.M.; Tumanov, V.P.

    1986-01-01

    The authors continue the quantitative analysis of endopulmonary cytograms by making an ultrastructural and autoradiographic study of lavage cells in chronic nonspecific inflammatory diseases of the lungs. Semithin sections of lavage cells incubated with tritium-uridine were prepared by light-microscopic authoradiography, then stained with azure II for the counting of the density and labeling index of the lavage cells. Ultrastructural analysis showed marked heterogeneity of the macrophage population in the bronchoalveolar washings from patients with chronic inflammation of the lungs. It is shown that the process of activation of the macrophagal system can take place quite rapidly and can be induced by several different factors which are discussed in the paper

  7. The relation of apple texture with cell wall nanostructure studied using an atomic force microscope.

    Science.gov (United States)

    Cybulska, Justyna; Zdunek, Artur; Psonka-Antonczyk, Katarzyna M; Stokke, Bjørn T

    2013-01-30

    In this study, the relation of the nanostructure of cell walls with their texture was investigated for six different apple cultivars. Cell wall material (CWM) and cellulose microfibrils were imaged by atomic force microscope (AFM). The mean diameter of cellulose microfibrils for each cultivar was estimated based on the AFM height topographs obtained using the tapping mode of dried specimens. Additionally, crystallinity of cellulose microfibrils and pectin content was determined. Texture of apple cultivars was evaluated by sensory and instrumental analysis. Differences in cellulose diameter as determined from the AFM height topographs of the nanostructure of cell walls of the apple cultivars are found to relate to the degree of crystallinity and pectin content. Cultivars with thicker cellulose microfibrils also revealed crisper, harder and juicier texture, and greater acoustic emission. The data suggest that microfibril thickness affects the mechanical strength of cell walls which has consequences for sensory and instrumental texture. Copyright © 2012 Elsevier Ltd. All rights reserved.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1993-11-01

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

  9. Batch-wise adsorption, saxs and microscopic studies of zeolite pelletized with biopolymeric alginate

    Directory of Open Access Journals (Sweden)

    E. Chmielewská

    2011-03-01

    Full Text Available Removal of nitrates, sulfate and Zn(II ions from aqueous solutions through adsorption onto biopolymeric alginate/clinoptilolite-rich tuff pellets was studied by using an equilibrium batch technique. The idea of this approach of biosorbent fabrication is to promote the native zeolite adsorption performance and thus to prepare more efficient amphoteric tailor-made products for specific environmental targets. A flexible component, i.e., alginate biopolymer, and a rigid component (pulverized zeolite were crosslinked using Fe(III and Ca(II chlorides, additively. The extent of adsorption was found to be considerably higher than with the other mostly natural adsorbents examined towards similar pollutants. The equilibrium adsorption data for the above pollutants were satisfactorily fitted to Freundlich and Langmuir isotherms, respectively. According to the linscale SAXS pattern, there was a strong background visible, which may indicate the presence of a considerable amount of biopolymeric phase in the composite samples analysed. Scanning Tunneling, Electron and Atomic Force Microscopies helped visualize their surface texture and morphology.

  10. Transmission-line resonators for the study of individual two-level tunneling systems

    Science.gov (United States)

    Brehm, Jan David; Bilmes, Alexander; Weiss, Georg; Ustinov, Alexey V.; Lisenfeld, Jürgen

    2017-09-01

    Parasitic two-level tunneling systems (TLS) emerge in amorphous dielectrics and constitute a serious nuisance for various microfabricated devices, where they act as a source of noise and decoherence. Here, we demonstrate a new test bed for the study of TLS in various materials which provides access to properties of individual TLS as well as their ensemble response. We terminate a superconducting transmission-line resonator with a capacitor that hosts TLS in its dielectric. By tuning TLS via applied mechanical strain, we observe the signatures of individual TLS strongly coupled to the resonator in its transmission characteristics and extract the coupling components of their dipole moments and energy relaxation rates. The strong and well-defined coupling to the TLS bath results in pronounced resonator frequency fluctuations and excess phase noise, through which we can study TLS ensemble effects such as spectral diffusion, and probe theoretical models of TLS interactions.

  11. Analytical electron microscope study of the omega phase transformation in a zirconium--niobium alloy

    Energy Technology Data Exchange (ETDEWEB)

    Zaluzec, N.J.

    1979-06-01

    An in-situ study of the as-quenched omega phase transformation in Zr--15% Nb was conducted between the temperatures of 77 and 300/sup 0/K using analytical electron microscopy. The domain size of the omega regions observed in this investigation was on the order of 30 A, consistent with previous observations in this system. No alignment of omega domains along <222> directions of the bcc lattice was observed and in-situ thermal cycling experiments failed to produce a long period structure of alternating ..beta.. and ..omega.. phase regions as predicted by one theory of this transformation. Several techniques of microstructural analysis were developed, refined, and standardized. Grouped under the general classification of Analytical Electron Microscopy (AEM) they provide the experimentalist with a unique tool for the microcharacterization of solids, allowing semiquantitative to quantitative analysis of the morphology, crystallography, elemental composition, and electronic structure of regions as small as 20 A in diameter. These techniques have complications, and it was necessary to study the AEM system used in this work so that instrumental artifacts which invalidate the information produced in the microscope environment might be eliminated. Once these factors had been corrected, it was possible to obtain a wealth of information about the microvolume of material under investigation. The microanalytical techniques employed during this research include: energy dispersive x-ray spectroscopy (EDS) using both conventional and scanning transmission electron microscopy (CTEM, STEM), transmission scanning electron diffraction (TSED), the stationary diffraction pattern technique, and electron energy loss spectroscopy (ELS) using a dedicated scanning transmission electron microscope (DSTEM).

  12. Laser microscope-spectrum analyzer for studying intracellular accumulation of near infrared emitting photosensitizers in vitro

    Directory of Open Access Journals (Sweden)

    Yu. S. Maklygina

    2015-01-01

    Full Text Available Measuring system based on the binocular microscope for analysis of intracellular accumulation of infrared IR photosenstizers allowing to obtain graphic data about state of analyzed objects, location of fluorescence foci and to obtain details of spectral profile of fluorescence emission centers in IR spectral region was developed. According to image of fluorescence signal distribution the location of photosensitizer accumulation in the cell may be detected accurately and the spectrum of fluorescence signal of near IR-range in the targeted point may be obtained. The developed system is quite comprehensive because there is an opportunity to choose technical parameters, operating modes, measuring methods and analysis. The advantage of the developed microscope-spectrum analyzer is an opportunity to focus emission and create high power intensity on the irradiated area by means of laser source with small-angle beam spreading, all this allow to perform ultra-precise operations with cells. Particularly, tunable size of the diaphragm opening in the far field allows to register fluorescence signal on certain cell organoids. By means of developed system the studies of accumulation of the new bacteriochlorine photosensitizers on HeLa cell line were performed. The system allowed to register accumulation of cancer cells with definite sites of selectively accumulated photosensitizer. The sites of fluorescence were the centers of accumulation of bacteriochlorine photosensitizer, this suggests that studied photosensitizer has a tendency for local accumulation in cellular organoids. The authors suggested that the developed system allowed to perform the effective and rapid screening of new photosensitizers, particularly IR bacteriochlorine photosensitizers. 

  13. Analytical electron microscope study of the omega phase transformation in a zirconium--niobium alloy

    International Nuclear Information System (INIS)

    Zaluzec, N.J.

    1979-06-01

    An in-situ study of the as-quenched omega phase transformation in Zr--15% Nb was conducted between the temperatures of 77 and 300 0 K using analytical electron microscopy. The domain size of the omega regions observed in this investigation was on the order of 30 A, consistent with previous observations in this system. No alignment of omega domains along directions of the bcc lattice was observed and in-situ thermal cycling experiments failed to produce a long period structure of alternating β and ω phase regions as predicted by one theory of this transformation. Several techniques of microstructural analysis were developed, refined, and standardized. Grouped under the general classification of Analytical Electron Microscopy (AEM) they provide the experimentalist with a unique tool for the microcharacterization of solids, allowing semiquantitative to quantitative analysis of the morphology, crystallography, elemental composition, and electronic structure of regions as small as 20 A in diameter. These techniques have complications, and it was necessary to study the AEM system used in this work so that instrumental artifacts which invalidate the information produced in the microscope environment might be eliminated. Once these factors had been corrected, it was possible to obtain a wealth of information about the microvolume of material under investigation. The microanalytical techniques employed during this research include: energy dispersive x-ray spectroscopy (EDS) using both conventional and scanning transmission electron microscopy (CTEM, STEM), transmission scanning electron diffraction (TSED), the stationary diffraction pattern technique, and electron energy loss spectroscopy (ELS) using a dedicated scanning transmission electron microscope

  14. Tunneling states in quasi crystals and in large lattice crystals

    International Nuclear Information System (INIS)

    Bert, Fabrice

    2001-01-01

    Amorphous materials possess specific low-energy excitations which are not found in simple crystals. Hence they show peculiar and, most remarkably, nearly universal low-temperature properties. In the phenomenological tunneling state model, these excitations arise from a tunneling effect of groups of atoms between nearly degenerate configurations. In order to improve our understanding of the microscopic nature of these tunneling states and their relation with structural disorder, we have studied various materials with an intermediate degree of order between crystalline and amorphous matter. Thus, using the propagation of acoustic waves, we have measured the acoustic properties, sound velocity and attenuation, in several quasicrystals and crystals with large unit cells between 15 mK and 40 K. A first experiment in a single-grain quasicrystal i-AlCuFe with a very high structural quality revealed the existence of tunneling states with a density of states similar to that of amorphous solids. Besides, measurements in the approximant phase R-AlLiCu and in two imperfect quasicrystals i-AlLiCu, one of them after annealing to improve its structural quality, showed that the density of states of the tunneling states increases with the quality of the quasicrystalline order. Therefore, tunneling states are not related to structural defects such as phasons but are intrinsic to quasicrystals. This is confirmed by the observation of a strong anisotropy of the tunneling state-phonons coupling in a two-dimension decagonal quasicrystal d-AlNiCo. We have also studied materials with a stronger long-range order, i.e. crystals with large unit cells. Single crystals of olivine and cordierite (28 and 116 atoms per cell respectively) showed tunneling states with a small density of states which seems to increase with the size of the unit cell. (author)

  15. A theoretical study on tunneling based biosensor having a redox-active monolayer using physics based simulation

    Science.gov (United States)

    Kim, Kyoung Yeon; Lee, Won Cheol; Yun, Jun Yeon; Lee, Youngeun; Choi, Seoungwook; Jin, Seonghoon; Park, Young June

    2018-01-01

    We developed a numerical simulator to model the operation of a tunneling based biosensor which has a redox-active monolayer. The simulator takes a realistic device structure as a simulation domain, and it employs the drift-diffusion equation for ion transport, the non-equilibrium Green's function formalism for electron tunneling, and the Ramo-Shockley theorem for accurate calculation of non-faradaic current. We also accounted for the buffer reaction and the immobilized peptide layer. For efficient transient simulation, the implicit time integration scheme is employed where the solution at each time step is obtained from the coupled Newton-Raphson method. As an application, we studied the operation of a recently fabricated reference-electrode free biosensor in various bias conditions and confirmed the effect of buffer reaction and the current flowing mechanism. Using the simulator, we also found a strategy to maximize the sensitivity of the tunneling based sensor.

  16. Correlating nerve conduction studies and clinical outcome measures on carpal tunnel syndrome: lessons from a randomized controlled trial

    NARCIS (Netherlands)

    Schrijver, Hans M.; Gerritsen, Annette A. M.; Strijers, Rob L. M.; Uitdehaag, Bernard M. J.; Scholten, Rob J. P. M.; de Vet, Henrica C. W.; Bouter, Lex M.

    2005-01-01

    The reported relationships between nerve conduction studies (NCS) and outcome measures in carpal tunnel syndrome (CTS) are weak to moderate. However, selection of patients may have confounded nonrandomized studies. NCS have potentially great value in selecting patients for a specific treatment and

  17. Temperature dependent tunneling study of CaFe1.96Ni0.04As2 single crystals

    International Nuclear Information System (INIS)

    Dutta, Anirban; Gupta, Anjan K.; Thamizhavel, A.

    2014-01-01

    We report on temperature dependent scanning tunneling microscopy and spectroscopy studies on CaFe 1.96 Ni 0.04 As 2 single crystals in 5.4 – 19.7 K temperature range across the normal metal - superconductor transition temperature, T C = 14K. The in-situ cleaved crystals show reasonably flat surface with signatures of atomic resolution. The tunnel spectra show significant spatial inhomogeneity below T C , which reduces significantly as the temperature goes above the T C . We discuss these results in terms of an inhomogeneous electronic phase that may exist due to the vicinity of this composition to the quantum critical point

  18. Comparison of three different sealer placement techniques: An In vitro confocal laser microscopic study

    Directory of Open Access Journals (Sweden)

    Avoy Kumar Dash

    2017-01-01

    Full Text Available Introduction: Three-dimensional obturation of the root canal system is the final objective of root canal therapy. Greater penetration of sealer in root dentine lesser will be the voids at the dentine–sealer interface. Hence, analysis of the dentin/sealer interface allows the determination of a filling technique which could obturate the root canals with least gaps and voids. Therefore, the aim of this study is to compare the depth and percentage of sealer penetration into root dentin using three different root canal sealer placement techniques under confocal laser scanning microscope. Materials and Methods: Thirty single-rooted teeth were selected and prepared. Adseal sealer (Meta Biomed, South Korea was mixed with Rhodamine B dye and applied using lentulo spiral (Dentsply Maillefer, USA as Group 1, bidirectional spiral (EZ-Fill– EDS, USA as Group 2, and ultrasonic endodontic tip (Sonofile– Dentsply Tulsa, USA as Group 3. Canals were then obturated with gutta-percha. The roots were sectioned at the 3 and 6-mm levels from the apical foramen and examined under confocal laser microscope. Results: Maximum mean depth and percentage of sealer penetration were observed for Group 1 and minimum for Group 3. Furthermore, statistical significant differences among Group 1 and Group 3 were found at 6-mm level and among Group 2 and Group 3 were found at 3-mm level (P < 0.05. Conclusion: The depth and percentage of sealer penetration of sealer are influenced by the type of placement technique and by the root canal level, with penetration decreasing apically. Lentulo spiral has shown better penetration of sealer than the bidirectional file and ultrasonics.

  19. Femtosecond tunneling response of surface plasmon polaritons

    DEFF Research Database (Denmark)

    Keil, Ulrich Dieter Felix; Ha, Taekjip; Jensen, Jacob Riis

    1998-01-01

    We obtain femtosecond (200 fs) time resolution using a scanning tunneling microscope on surface plasmon polaritons (SPPs) generated by two 100 fs laser beams in total internal reflection geometry. The tunneling gap dependence of the signal clearly indicates the tunneling origin of the signal...... and suggests that nanometer spatial resolution can be obtained together with femtosecond temporal resolution. This fast response, in contrast to the picosecond decay time of SPPs revealed by differential reflectivity measurements, can be attributed to a coherent superposition of SPPs rectified at the tunneling...... junction. (C) 1998 American Institute of Physics. [S0003-6951(98)02223-2]....

  20. Band structure of Heusler compounds studied by photoemission and tunneling spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Arbelo Jorge, Elena

    2011-07-01

    Heusler compounds are key materials for spintronic applications. They have attracted a lot of interest due to their half-metallic properties predicted by band structure calculations. The aim of this work is to evaluate experimentally the validity of the predictions of half metallicity by band structure calculations for two specific Heusler compounds, Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa. Two different spectroscopy methods for the analysis of the electronic properties were used: Angular Resolved Ultraviolet Photoemission Spectroscopy (ARUPS) and Tunneling Spectroscopy. Heusler compounds are prepared as thin films by RF-sputtering in an ultra high vacuum system. For the characterization of the samples, bulk and surface crystallographic and magnetic properties of Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa are studied. X-ray and electron diffraction reveal a bulk and surface crossover between two different types of sublattice order (from B2 to L2{sub 1}) with increasing annealing temperature. X-ray magnetic circular dichroism results show that the magnetic properties in the surface and bulk are identical, although the magnetic moments obtained are 5 % below from the theoretically predicted. By ARUPS evidence for the validity of the predicted total bulk density of states (DOS) was demonstrated for both Heusler compounds. Additional ARUPS intensity contributions close to the Fermi energy indicates the presence of a specific surface DOS. Moreover, it is demonstrated that the crystallographic order, controlled by annealing, plays an important role on broadening effects of DOS features. Improving order resulted in better defined ARUPS features. Tunneling magnetoresistance measurements of Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} and Co{sub 2}MnGa based MTJ's result in a Co{sub 2}FeAl{sub 0.3}Si{sub 0.7} spin polarization of 44 %, which is the highest experimentally obtained value for this compound, although it is lower than the 100 % predicted. For Co

  1. Spin-resolved tunneling studies of the exchange field in EuS/Al bilayers.

    Science.gov (United States)

    Xiong, Y M; Stadler, S; Adams, P W; Catelani, G

    2011-06-17

    We use spin-resolved electron tunneling to study the exchange field in the Al component of EuS/Al bilayers, in both the superconducting and normal-state phases of the Al. Contrary to expectation, we show that the exchange field H(ex) is a nonlinear function of applied field, even in applied fields that are well beyond the EuS coercive field. Furthermore, the magnitude H(ex) is unaffected by the superconducting phase. In addition, H(ex) decreases significantly with increasing temperature in the temperature range of 0.1-1 K. We discuss these results in the context of recent theories of generalized spin-dependent boundary conditions at a superconductor-ferromagnet interface.

  2. Hydrogen adsorption on Ru(001) studied by Scanning TunnelingMicroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Tatarkhanov, Mous; Rose, Franck; Fomin, Evgeny; Ogletree, D.Frank; Salmeron, Miquel

    2008-01-18

    The adsorption of hydrogen on Ru(001) was studied by scanning tunneling microscopy at temperatures around 50 K. Hydrogen was found to adsorb dissociatively forming different ordered structures as a function of coverage. In order of increasing coverage {theta} in monolayers (ML) these were ({radical}3 x {radical}3)r30{sup o} at {theta} = 0.3 ML; (2 x 1) at {theta} = 0.50 ML, (2 x 2)-3H at {theta} = 0.75, and (1 x 1) at {theta} = 1.00. Some of these structures were observed to coexist at intermediate coverage values. Close to saturation of 1 ML, H-vacancies (unoccupied three fold fcc hollow Ru sites) were observed either as single entities or forming transient aggregations. These vacancies diffuse and aggregate to form active sites for the dissociative adsorption of hydrogen.

  3. Preliminary studies on the Marcoule site, using a wind-tunnel

    International Nuclear Information System (INIS)

    Chassany, J.Ph.; Salaun-Penquer, G.

    1961-01-01

    The tests were carried out in the 3.30 x 2.20 subsonic elliptical wind-tunnel of the Marseille Institute of fluid mechanics, on a 1/1000 scale model measuring 3 m x 3 m. The aerodynamic field developing above the site, made visible by ammonium, hydro-chlorate fumes, and the residues were observed and filmed by means of a synchronised cine-camera with stroboscopic lighting for 4 wind directions. The fall-out from the various waste products was obtained from a spraying of lead acetate solution on the model and hydrogen sulphide emissions. The zones of maximum pollution can be determined from a study of the film taken during the blackening of the spots. (author) [fr

  4. Scanning tunneling microscopy studies of organic monolayers adsorbed on the rhodium(111) crystal surface

    Energy Technology Data Exchange (ETDEWEB)

    Cernota, Paul Davis [Univ. of California, Berkeley, CA (United States)

    1999-08-01

    Scanning Tunneling Microscopy studies were carried out on ordered overlayers on the (111) surface of rhodium. These adsorbates include carbon monoxide (CO), cyclohexane, cyclohexene, 1,4-cyclohexadiene, para-xylene, and meta-xylene. Coadsorbate systems included: CO with ethylidyne, CO with para- and meta-xylene, and para-xylene with meta-xylene. In the case of CO, the structure of the low coverage (2x2) overlayer has been observed. The symmetry of the unit cell in this layer suggests that the CO is adsorbed in the 3-fold hollow sites. There were also two higher coverage surface structures with (√7x√7) unit cells. One of these is composed of trimers of CO and has three CO molecules in each unit cell. The other structure has an additional CO molecule, making a total of four. This extra CO sits on a top site.

  5. Effectiveness of PELOID therapy in carpal tunnel syndrome: A randomized controlled single blind study

    Science.gov (United States)

    Metin Ökmen, Burcu; Kasapoğlu Aksoy, Meliha; Güneş, Aygül; Eröksüz, Riza; Altan, Lale

    2017-08-01

    Carpal tunnel syndrome(CTS) is the most common neuromuscular cause of upper extremity disability. We aimed to investigate the effectiveness of peloid therapy in patients with CTS. This randomized, controlled, single-blind study enrolled 70 patients between the ages of 30 to 65 who had a diagnosis of either mild, mild-to-moderate, or moderate CTS. The patients were randomized into two groups using random number table. In the first group, (Group 1)( n = 35), patients were given splint (every night for 6 weeks) + peloid treatment(five consecutive days a week for 2 weeks) and in the second group, (Group 2)( n = 28), patients received splint treatment(every night for 6 weeks) alone. The patients were assessed by using visual analog scale(VAS) for pain, electroneuromyography(ENMG), the Boston Carpal Tunnel Syndrome Questionnaire(BCTSQ), hand grip strength(HGS), finger grip strength(FGS), and Short Form-12(SF-12). The data were obtained before treatment(W0), immediately after treatment(W2), and one month after treatment(W6). Both in Group 1 and 2, there was a statistically significant improvement in all the evaluation parameters at W2 and W6 when compared to W0( p < 0.05). Comparison of the groups with each other revealed significantly better results for VAS, BCTSQ, mSNCV, SF-12 in Group 1 than in Group 2 at W2( p < 0.05). There was also a statistically significant difference in favor of Group 1 for VAS, BCTSQ, FGS and MCS at W6 when compared to W0 ( p < 0.05). The results of our study demonstrated that in patients with CTS; peloid + splint treatment was more effective than splint treatment alone in pain, functionality and life quality both at after treatment(W2) and one month after treatment (W6). We may suggest peloid as a supplementary therapeutic agent in CTS.

  6. A study of interpolation method in diagnosis of carpal tunnel syndrome

    Directory of Open Access Journals (Sweden)

    Alireza Ashraf

    2013-01-01

    Full Text Available Context: The low correlation between the patients′ signs and symptoms of carpal tunnel syndrome (CTS and results of electrodiagnostic tests makes the diagnosis challenging in mild cases. Interpolation is a mathematical method for finding median nerve conduction velocity (NCV exactly at carpal tunnel site. Therefore, it may be helpful in diagnosis of CTS in patients with equivocal test results. Aim: The aim of this study is to evaluate interpolation method as a CTS diagnostic test. Settings and Design: Patients with two or more clinical symptoms and signs of CTS in a median nerve territory with 3.5 ms ≤ distal median sensory latency <4.6 ms from those who came to our electrodiagnostic clinics and also, age matched healthy control subjects were recruited in the study. Materials and Methods: Median compound motor action potential and median sensory nerve action potential latencies were measured by a MEDLEC SYNERGY VIASIS electromyography and conduction velocities were calculated by both routine method and interpolation technique. Statistical Analysis Used: Chi-square and Student′s t-test were used for comparing group differences. Cut-off points were calculated using receiver operating characteristic curve. Results: A sensitivity of 88%, specificity of 67%, positive predictive value (PPV and negative predictive value (NPV of 70.8% and 84.7% were obtained for median motor NCV and a sensitivity of 98.3%, specificity of 91.7%, PPV and NPV of 91.9% and 98.2% were obtained for median sensory NCV with interpolation technique. Conclusions: Median motor interpolation method is a good technique, but it has less sensitivity and specificity than median sensory interpolation method.

  7. Water Tunnel Facility

    Data.gov (United States)

    Federal Laboratory Consortium — NETL’s High-Pressure Water Tunnel Facility in Pittsburgh, PA, re-creates the conditions found 3,000 meters beneath the ocean’s surface, allowing scientists to study...

  8. Liquid phase epitaxy of abrupt junctions in InAs and studies of injection radiative tunneling processes

    International Nuclear Information System (INIS)

    Bull, D.J.

    1977-01-01

    The p-n junction in a InAs crystal, by liquid phase epitaxy is obtained. The processes of injection and tunneling radiative recombination by emitted radiation from active region of p-n junction for low injection current are studied. (M.C.K.) [pt

  9. Hydrogen bond nature of ferroelectric material studied by X-ray and neutron diffraction. Electric dipole moment and proton tunneling

    International Nuclear Information System (INIS)

    Noda, Yukio; Kiyanagi, Ryoji; Mochida, Tomoyuki; Sugawara, Tadashi

    2006-01-01

    Hydrogen bond nature of MeHPLN and BrHPLN is studied using x-ray and neutron diffraction technique. We found that electric dipole moment of hydrogen atom plays an important role for the phase transition, and proton tunneling model is confirmed on this isolated hydrogen bond system. (author)

  10. Fuel use and metabolic response to endurance exercise : a wind tunnel study of a long-distance migrant shorebird

    NARCIS (Netherlands)

    Jenni-Eiermann, Susanne; Jenni, Lukas; Kvist, Anders; Lindström, Åke; Piersma, Theunis; Visser, G. Henk

    This study examines fuel use and metabolism in a group of long-distance migrating birds, red knots Calidris canutus (Scolopacidae), flying under controlled conditions in a wind tunnel for up to 10 h. Data are compared with values for resting birds fasting for the same time. Plasma levels of free

  11. Study on the traffic air pollution inside and outside a road tunnel in Shanghai, China.

    Directory of Open Access Journals (Sweden)

    Rui Zhou

    Full Text Available To investigate the vehicle induced air pollution situations both inside and outside the tunnel, the field measurement of the pollutants concentrations and its diurnal variations was performed inside and outside the Xiangyin tunnel in Shanghai from 13:00 on April 24th to 13:00 on April 25th, 2013. The highest hourly average concentrations of pollutants were quantified that CO, NO, NO2 and NOX inside the tunnel were 13.223 mg/m3, 1.829 mg/m3, 0.291 mg/m3 and 3.029 mg/m3, respectively, while the lowest ones were 3.086 mg/m3, 0.344 mg/m3, 0.080 mg/m3 and 0.619 mg/m3. Moreover, the concentrations of pollutants were higher during the daytime, and lower at night, which is relevant to the traffic conditions inside the tunnel. Pollutants concentrations inside the tunnel were much higher than those outside the tunnel. Then in a case of slow wind, the effect of wind is much smaller than the impact of pollution sources. Additionally, the PM2.5 concentrations climbed to the peak sharply (468.45 µg/m3 during the morning rush hours. The concentrations of organic carbon (OC and elemental carbon (EC in PM2.5 inside the tunnel were 37.09-99.06 µg/m3 and 22.69-137.99 µg/m3, respectively. Besides, the OC/EC ratio ranged from 0.72 to 2.19 with an average value of 1.34. Compared with the results of other tunnel experiments in Guangzhou and Shenzhen, China, it could be inferred that the proportion of HDVs through the Xiangyin tunnel is relatively lower.

  12. Tunneling progress on the Yucca Mountain Project

    International Nuclear Information System (INIS)

    Hansmire, W.H.; Munzer, R.J.

    1996-01-01

    The current status of tunneling progress on the Yucca Mountain Project (YMP) is presented in this paper. The Exploratory Studies Facility (ESF), a key part of the YMP, has been long in development and construction is ongoing. This is a progress report on the tunneling aspects of the ESF as of January 1, 1996. For purposes of discussion in this summary, the tunneling has progressed in four general phases. The paper describes: tunneling in jointed rock under low stress; tunneling through the Bow Ridge Fault and soft rock; tunneling through the Imbricate Fault Zone; and Tunneling into the candidate repository formation

  13. A study on the effect of thiotepa on mice spermatogenesis using light and electronic microscope.

    Science.gov (United States)

    Nejad, D M; Rad, J S; Roshankar, L; Karimipor, M; Ghanbari, A A; Aazami, A; Valilou, M R

    2008-08-01

    The present study was designed to explore the spermatogenic effect of intraperitoneal administration of thiotepa in mice. It is known the chemotherapy could affect testicular function and result in infertility. There are few reports on the side effect of thiotepa on spermatogenesis when are used as anticancer drug. Therefore, in the present study the effect of thiotepa on spermatogenesis was evaluated by electron microscopy. A total of 20 balb/c mice were used in this study. They were divided into control and thiotepa treated groups. Thiotepa was administrated as 2.5 mg kg(-1) for 5 days. The mice were sacrificed after 5 weeks and testicular specimens were removed, fixed in boueins fixative and 2.5% Glutaraldehide then prepared for light and electron microscopic study. Light microscopy showed that the thickness of germinal epithelium was decreased in thiotepa treated group and many seminiferous tubules have lost germinal cells. Electron microscopy revealed that in experimental group several intercellular spaces appeared between spermatogonial and sertoli cells. The basement membrane became irregular and intercellular vacuoles were present in sertoli and spermatogonial cells. Nuclear chromatin was condensed and there were several vacuolated mitochondria. It was indicated that thiotepa affected testicular germinal epithelium by both cytotoxic effect and induction of apoptosis.

  14. Synchrotron-based X-ray microscopic studies for bioeffects of nanomaterials.

    Science.gov (United States)

    Zhu, Ying; Cai, Xiaoqing; Li, Jiang; Zhong, Zengtao; Huang, Qing; Fan, Chunhai

    2014-04-01

    There have been increasing interests in studying biological effects of nanomaterials, which are nevertheless faced up with many challenges due to the nanoscale dimensions and unique chemical properties of nanomaterials. Synchrotron-based X-ray microscopy, an advanced imaging technology with high spatial resolution and excellent elemental specificity, provides a new platform for studying interactions between nanomaterials and living systems. In this article, we review the recent progress of X-ray microscopic studies on bioeffects of nanomaterials in several living systems including cells, model organisms, animals and plants. We aim to provide an overview of the state of the art, and the advantages of using synchrotron-based X-ray microscopy for characterizing in vitro and in vivo behaviors and biodistribution of nanomaterials. We also expect that the use of a combination of new synchrotron techniques should offer unprecedented opportunities for better understanding complex interactions at the nano-biological interface and accounting for unique bioeffects of nanomaterials. Synchrotron-based X-ray microscopy is a non-destructive imaging technique that enables high resolution spatial mapping of metals with elemental level detection methods. This review summarizes the current use and perspectives of this novel technique in studying the biology and tissue interactions of nanomaterials. Copyright © 2014 Elsevier Inc. All rights reserved.

  15. Transmission electron microscope studies of crystalline LiNbO3

    International Nuclear Information System (INIS)

    Pareja, R.; Gonzalez, R.; Chen, Y.

    1984-01-01

    Transmission electron microscope investigations in both as-grown and hydrogen-reduced LiNbO 3 reveal that niobium oxide precipitates can be produced by in situ irradiations in the electron microscope. The precipitation process is produced by a combined effect of ionizing electrons and the thermal heating of the specimens during irradiation. It is proposed that the composition of the precipitates is primarily Nb 2 O 5

  16. Case Study on Influence of Step Blast-Excavation on Support Systems of Existing Service Tunnel with Small Interval

    Directory of Open Access Journals (Sweden)

    Shaorui Sun

    2013-01-01

    Full Text Available During the construction of newly built tunnel (NBT adjacent to the existing service tunnel (EST, stability of the EST with small interval is affected by vibration waves which are caused by blasting load. The support structures of the EST will be cracked and damaged, while the unreasonable blast-excavation methods are adopted. Presently, the studies on behavior of support structure in the EST under blasting load are not totally clear, especially for the bolts system. Besides, the responses of support structure on blasting load are lacking comprehensive research. In this paper, New Zuofang tunnel is taken as a study case to study the influence of step blast-excavation in NBT on support structures of the EST through field experiment and numerical simulation. Some data, such as blasting vibration velocity (BVV and frequency of support structures, are obtained through field measurement. Based on these data, the formula of BVVs is obtained. Research on stability of tunnel support structures affected by step blast-excavation is conducted using numerical simulation method. The dynamic-plastic constitutive model is adopted in the software ABAQUS to assess safety of support structures. The range and degree of damage for the support structures are obtained. In addition, change laws of axial force and stress with time for the bolts are analyzed.

  17. Destructive quantum interference in spin tunneling problems

    OpenAIRE

    von Delft, Jan; Henley, Christopher L.

    1992-01-01

    In some spin tunneling problems, there are several different but symmetry-related tunneling paths that connect the same initial and final configurations. The topological phase factors of the corresponding tunneling amplitudes can lead to destructive interference between the different paths, so that the total tunneling amplitude is zero. In the study of tunneling between different ground state configurations of the Kagom\\'{e}-lattice quantum Heisenberg antiferromagnet, this occurs when the spi...

  18. Gross and microscopic findings in patients submitted to nonablative full-face resurfacing using intense pulsed light: a preliminary study.

    Science.gov (United States)

    Hernández-Pérez, Enrique; Ibiett, Erick Valencia

    2002-08-01

    Intense pulsed light (IPL) is a noncoherent, nonlaser, filtered flashlamp emitting a broadband visible light that has been shown to be effective in photoepilation, as well as in a number of vascular and pigmented lesions of the skin. Their efficacy has also been reported recently in the treatment of photodamaged facial skin. In the last condition, however, there are few studies showing the clinical and microscopic changes produced by IPL. To assess the gross and microscopic changes that occur in photodamaged skin submitted to nonablative full-face resurfacing (NAFFR) using IPL. Five women were submitted to five NAFFR sessions using IPL, one every 2 weeks. Skin biopsies and photographs were taken on all of the patients before the first procedure and after the last one, as well as weekly clinical assessment. Data concerning skin features (wrinkles, oiliness, thickness, dilated pores, and general appearance) were all assessed. Microscopic improvement of the aging features in the epidermis and dermis were all assessed. For the statistical analysis a t test for small samples was used. All the patients showed clinical and microscopic improvement in every one of the parameters assessed. The t test for small samples showed a statistically significant difference (P Facial photodamage was clinically and microscopically improved using IPL. Use of IPL as a rejuvenating method seems to be promising, with minimal side effects, a wide safety margin, and minimal downtime.

  19. Studying of a Tunneling Accelerometer with Piezoelectric Actuation and Fuzzy Controller

    Directory of Open Access Journals (Sweden)

    Ahmadali Tahmasebi Moradi

    2008-03-01

    Full Text Available This report demonstrates the design of closed-loop micro accelerometer sensor. Proposed sensor consists of a polysilicon cantilever micro beam as a proof mass and uses the extreme sensitivity of electron tunneling to variations in electrode separation as sensing element of the sensor. The model uses piezoelectric forces as an actuating element to control the separation between the tunneling electrodes with a low voltage due to large piezoelectric constant. In order to have a proper response time a Fuzzy controller is considered which can be very useful, fast, and reliable. The inputs for the mentioned controller are tunneling current error, gradient of the tunneling current and the summation of errors. And the output is the piezoelectric voltage. Due to the simulation and its results, it is seen that the proposed micro accelerometer have high linearity and dynamic range and also have good respond to the step and sinusoidal acceleration.

  20. New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

    Directory of Open Access Journals (Sweden)

    Jinxing Lai

    2015-01-01

    Full Text Available In recent years, with the rapid growth of economy and sharp rise of motor vehicles in China, the pavement skid resistance in tunnel portals has become increasingly important in cold region. However, the deicing salt, snow removal with machine, and other antiskid measures adopted by highway maintenance division have many limitations. To improve the treatment effect, we proposed a new snow-melting approach employing electric heat tracing, in which heating cables are installed in the structural layer of road. Through the field experiment, laboratory experiment, and numerical investigation, structure type, heating power, and preheating time of the flexible pavement heating system in tunnel portal were systematically analyzed, and advantages of electric heat tracing technology in improving the pavement skid resistance in tunnel portal were also presented. Therefore, such new technology, which offers new snow-melting methods for tunnel portal, bridge, mountainous area, and large longitudinal slope in cold region, has promising prospect for extensive application.

  1. Recognition tunneling

    International Nuclear Information System (INIS)

    Lindsay, Stuart; He Jin; Zhang Peiming; Chang Shuai; Huang Shuo; Sankey, Otto; Hapala, Prokop; Jelinek, Pavel

    2010-01-01

    Single molecules in a tunnel junction can now be interrogated reliably using chemically functionalized electrodes. Monitoring stochastic bonding fluctuations between a ligand bound to one electrode and its target bound to a second electrode ('tethered molecule-pair' configuration) gives insight into the nature of the intermolecular bonding at a single molecule-pair level, and defines the requirements for reproducible tunneling data. Simulations show that there is an instability in the tunnel gap at large currents, and this results in a multiplicity of contacts with a corresponding spread in the measured currents. At small currents (i.e. large gaps) the gap is stable, and functionalizing a pair of electrodes with recognition reagents (the 'free-analyte' configuration) can generate a distinct tunneling signal when an analyte molecule is trapped in the gap. This opens up a new interface between chemistry and electronics with immediate implications for rapid sequencing of single DNA molecules. (topical review)

  2. Recognition tunneling

    Energy Technology Data Exchange (ETDEWEB)

    Lindsay, Stuart; He Jin; Zhang Peiming; Chang Shuai; Huang Shuo [Biodesign Institute, Arizona State University, Tempe, AZ 85287 (United States); Sankey, Otto [Department of Physics, Arizona State University, Tempe, AZ 85287 (United States); Hapala, Prokop; Jelinek, Pavel [Institute of Physics, Academy of Sciences of the Czech Republic, Cukrovarnicka 10, 1862 53, Prague (Czech Republic)

    2010-07-02

    Single molecules in a tunnel junction can now be interrogated reliably using chemically functionalized electrodes. Monitoring stochastic bonding fluctuations between a ligand bound to one electrode and its target bound to a second electrode ('tethered molecule-pair' configuration) gives insight into the nature of the intermolecular bonding at a single molecule-pair level, and defines the requirements for reproducible tunneling data. Simulations show that there is an instability in the tunnel gap at large currents, and this results in a multiplicity of contacts with a corresponding spread in the measured currents. At small currents (i.e. large gaps) the gap is stable, and functionalizing a pair of electrodes with recognition reagents (the 'free-analyte' configuration) can generate a distinct tunneling signal when an analyte molecule is trapped in the gap. This opens up a new interface between chemistry and electronics with immediate implications for rapid sequencing of single DNA molecules. (topical review)

  3. The muscles in club foot--a histological histochemical and electron microscopic study.

    Science.gov (United States)

    Isaacs, H; Handelsman, J E; Badenhorst, M; Pickering, A

    1977-11-01

    In talipes equino-varus the diminished bulk of the calf muscle suggests a neuromuscular defect. Accordingly, biopsies were taken from the postero-medial and peroneal muscle groups, and occasionally from abductor hallucis, in sixty patients mostly under the age of five years; 111 were studied histochemically and histologically, and a further fifty-three by electron-microscopy. Histochemical anomalies were revealed in ninety-two specimens; the muscle fibres in the other nineteen varied in size but were abnormal at the ultramicroscopic level, as were all specimens examined with the electron microscope. Evidence of neurogenic disease was seen in most instances and was more obvious in the older patients. The pattern of abnormality was similar in both muscle groups. It is thought that shortening of the postero-medial muscles may result from a small increase of fibrosis due to minor innervation changes occurring in intra-uterine life. There is evidence that immobilisation, stretching or relaxation of muscles does not account for the anomalies observed. This study of the extrinsic muscles in talipes equino-varus indicates a dominant neurogenic factor in its causation.

  4. Microscopic study of {sup 1}S{sub 0} superfluidity in dilute neutron matter

    Energy Technology Data Exchange (ETDEWEB)

    Pavlou, G.E.; Mavrommatis, E. [National and Kapodistrian University of Athens, Physics Department, Division of Nuclear and Particle Physics, Athens (Greece); Moustakidis, C. [Aristotelian University of Thessaloniki, Department of Theoretical Physics, Thessaloniki (Greece); Clark, J.W. [Washington University, McDonnell Center for the Space Sciences and Department of Physics, St. Louis, MO (United States); University of Madeira, Center for Mathematical Sciences, Funchal (Portugal)

    2017-05-15

    Singlet S-wave superfluidity of dilute neutron matter is studied within the correlated BCS method, which takes into account both pairing and short-range correlations. First, the equation of state (EOS) of normal neutron matter is calculated within the Correlated Basis Function (CBF) method in the lowest cluster order using the {sup 1}S{sub 0} and {sup 3}P components of the Argonne V{sub 18} potential, assuming trial Jastrow-type correlation functions. The {sup 1}S{sub 0} superfluid gap is then calculated with the corresponding component of the Argonne V{sub 18} potential and the optimally determined correlation functions. The dependence of our results on the chosen forms for the correlation functions is studied, and the role of the P-wave channel is investigated. Where comparison is meaningful, the values obtained for the {sup 1}S{sub 0} gap within this simplified scheme are consistent with the results of similar and more elaborate microscopic methods. (orig.)

  5. Somatic Embryos in Catharanthus roseus: A Scanning Electron Microscopic Study

    Directory of Open Access Journals (Sweden)

    Junaid ASLAM

    2014-06-01

    Full Text Available Catharanthus roseus (L. G. Don is an important medicinal plant as it contains several anti-cancerous compounds, like vinblastine and vincristine. Plant tissue culture technology (organogenesis and embryogenesis has currently been used in fast mass propagating raw materials for secondary metabolite synthesis. In this present communication, scanning electron microscopic (SEM study of somatic embryos was conducted and discussed. The embryogenic callus was first induced from hypocotyls of in vitro germinated seeds on which somatic embryos, differentiated in numbers, particularly on 2,4-D (1.0 mg/L Murashige and Skoog (MS was medium. To understand more about the regeneration method and in vitro formed embryos SEM was performed. The SEM study revealed normal somatic embryo origin and development from globular to heart-, torpedo- and then into cotyledonary-stage of embryos. At early stage, the embryos were clustered together in a callus mass and could not easily be detached from the parental tissue. The embryos were often long cylindrical structure with or without typical notch at the tip. Secondary embryos were also formed on primary embryo structure. The advanced cotyledonary embryos showed prominent roots and shoot axis, which germinated into plantlets. The morphology, structure and other details of somatic embryos at various stages were presented.

  6. Ultra-morphology of root surface subsequent to periodontal instrumentation: A scanning electron microscope study

    Directory of Open Access Journals (Sweden)

    Parveen Dahiya

    2012-01-01

    Full Text Available Background: The aim of this study was to compare root surface characteristic following root planing with various hand and power driven instruments. Materials and Methods: A total of 20 single rooted teeth were used in this study, of which two specimens were used as control (no instrumentation done and remaining 18 specimens were equally divided into three groups. Specimens from each group were then subjected to root planing by one of the following instruments: (1 a Gracey curette (2 Ultrasonic tip and (3 a Rotary bur. In each case, the time required for scaling and root planing was measured. After treatment, the specimens were observed under scanning electron microscope and surface roughness was measured by using Roughness and loss of tooth substance index (RLTSI. Results: The mean RLTSI scores for Gracey curette, ultrasonic and rotary instrument group were 2.5, 2.0 and 0.667 respectively. The mean scores of time spent for scaling and root planing by Gracey curette, ultrasonic and rotary instrument group in seconds were 42.50, 35.83 and 54.50. Conclusion: All the three instruments namely Gracey curette, Ultrasonic tip and Rotary bur were effective in mechanical debridement of root surface. The results favoured the use of rotary instruments for root planing to achieve smooth clean root surface; however, the use of rotary instrument was more time consuming which might limit its use in clinical practice.

  7. Development of Conductive Boron-Doped Diamond Electrode: A microscopic, Spectroscopic, and Voltammetric Study

    Directory of Open Access Journals (Sweden)

    Kevin E. Bennet

    2013-12-01

    Full Text Available Building on diamond characteristics such as hardness, chemical inertness and low electron emission threshold voltage, the current microscopic, spectroscopic and voltammetric investigations are directed towards improving the properties of electrode coating materials for their future use in clinical studies of deep brain stimulation via fast-scan cyclic voltammetry (FSCV. In this study we combine the capabilities of confocal Raman mapping in providing detailed and accurate analysis of local distributions of material constituents in a series of boron-doped polycrystalline diamond films grown by chemical vapor deposition, with information from the more conventional techniques of scanning electron microscopy (SEM and infrared absorption spectroscopy. Although SEM images show a uniform distribution of film crystallites, they have the limitation of being unable to differentiate the distribution of boron in the diamond. Values of 1018–1021 atoms/cm3 of boron content have been estimated from the absorption coefficient of the 1290 cm−1 infrared absorption band and from the 500 cm−1 Raman vibration. The observed accumulation of boron atoms and carbon sp2 impurities at the grain boundaries suggests that very high doping levels do not necessarily contribute to improvement of the material’s conductivity, corroborating with voltammetric data. FSCV results also indicate an enhanced stability of analyte detection.

  8. Scanning electron microscope studies of anesthetized Tricula aperta, vector of mekong Schistosoma.

    Science.gov (United States)

    Kitikoon, V; Rivera, E R

    1982-12-01

    Nembutal, menthol, Ketaset, and Curarine were used to anesthetize beta race of Tricula aperta snails in preparation for study by scanning electron microscopy. The snails remained sensitive to the glutaraldehyde fixative in low level anesthesia of nembutal, menthol and Ketaset. Snails were also sensitive to Curarine and retracted into their shells. The best relaxations were obtained by initial anesthesia with nembutal or menthol followed by curarine. Snails relaxed by this procedure showed relatively little reaction to the fixative solution and remained extended outside their shells. The surface ultrastructure of the snails was well preserved, showing microvillate, secretory, and ciliated sensory cells. The mucoid secretions remained on the surface of cilia on the body and foot of the snails as spherical granules. There were two types of ciliated cells: (1) Those with few short cilia showing 1-3 microns above the microvilli of surrounding cells and (2) Those with numerous cilia up to 10 microns long. Results of transmission electron microscopic studies of these snails show no disruption of the ultrastructure of the surface cells.

  9. Domain wall displacements in amorphous films and multilayers studied with a magnetic force microscope

    International Nuclear Information System (INIS)

    Pokhil, T.G.

    1997-01-01

    The magnetic force microscope (MFM) was used to study the displacement of domain walls (DW) in amorphous TbFe alloy films and Co/Pd multilayer films with high spatial resolution. The reversible bending of domain wall segments pinned to defects and irreversible, jumplike displacement of domain wall segments were imaged with the MFM in an applied magnetic field. The maximum reversible displacement of domain walls was 50 endash 100 nm and the length of the segments which reversibly curved in the field was about 150 nm. Measurement of the change in radius of curvature of a DW segment in response to an applied field allowed estimation of the DW energy density and self-demagnetizing field of the film acting on the DW. The DW energy density for the TbFe films was about 1 erg/cm 2 . It was shown that the self-demagnetizing field acting on a domain wall depends on the domain structure surrounding the studied DW segment. For instance, for a film with saturation magnetization 100 G and thickness 80 nm, which exhibited a mazelike domain structure, the demagnetizing field varied from 100 G in the center of a mazelike domain to 400 G near the edge of a domain. The irreversible displacement of a DW was not a continuous process. The 200 endash 400 nm long DW segments exhibited jumplike motion over distances of 100 endash 150 nm. copyright 1997 American Institute of Physics

  10. [Anatomical study on the femoral tunnel anatomy reconstruction of anterior cruciate ligament].

    Science.gov (United States)

    Dong, Yi-Long; Cai, Chun-Yuan; Jiang, Wen-Hui; Jiang, Gang-Yi; Qian, Yue-Nan; Zhao, Zhang-Wei; Yang, Guo-Jing

    2013-09-01

    To measure anatomical data of the femoral tunnel anatomy reconstruction of anterior cruciate ligament (ACL), so provide anatomical basis for clinical anatomy reconstruction of ACL. There were 30 adults' cadaveric knee specimens. The ACL femoral tunnel was reconstructed through anterior medial approach (AMP) in genuflex position of 120 degree, and was marked by Kirschner. The soft tissue of the specimen was removed and the femoral condyle was split at the middle side. The index including length of the femoral tunnel, the distance from internal opening of tunnel to cortical edge of femoral condyle and vertical distance to the top of femoral intercondylar notch were measured. Then the time position of internal opening of tunnel in the intercondylar notch was recorded, and the location of outside opening of tunnel to the femoral condyle was detected. The mean length of the femoral tunnel was (36.35 +/- 3.14) mm (ranged, 30.65 to 42.35 mm). The distance from internal opening of tunnel to cortical edge of femoral condyle was (17.84 +/- 3.35) mm (ranged, 14.02 to 23.49 mm), vertical distance to the top of femoral intercondylar notch was (14.05 +/- 2.32) mm (ranged, 9.17 to 20.08 mm). According to the way of circular dial,internal opening of tunnel located at 02:30 +/- 00:10 (ranged, 01:50 to 02:50) in the left knee,and 09:30 +/- 0:15 (ranged, 08:30 to 10:40) in the right knee. The outside opening of femoral tunnel located at (3.16 +/- 2.51) mm (ranged, 1.61 to 6.30 mm) to the proximal end of external epicondyle of femur, and (4.25 +/- 2.16) mm (ranged, 1.73 to 8.52 mm) to the posterior of external epicondyle of femur. The anatomical features of femoral tunnel for reconstruction of ACL is revealed,which will provide anatomical basis for clinical practice.

  11. Microscopic colitis

    DEFF Research Database (Denmark)

    Münch, A; Aust, D; Bohr, Jakob

    2012-01-01

    Microscopic colitis (MC) is an inflammatory bowel disease presenting with chronic, non-bloody watery diarrhoea and few or no endoscopic abnormalities. The histological examination reveals mainly two subtypes of MC, lymphocytic or collagenous colitis. Despite the fact that the incidence in MC has...... been rising over the last decades, research has been sparse and our knowledge about MC remains limited. Specialists in the field have initiated the European Microscopic Colitis Group (EMCG) with the primary goal to create awareness on MC. The EMCG is furthermore a forum with the intention to promote...

  12. Martian Microscope

    Science.gov (United States)

    2004-01-01

    The microscopic imager (circular device in center) is in clear view above the surface at Meridiani Planum, Mars, in this approximate true-color image taken by the panoramic camera on the Mars Exploration Rover Opportunity. The image was taken on the 9th sol of the rover's journey. The microscopic imager is located on the rover's instrument deployment device, or arm. The arrow is pointing to the lens of the instrument. Note the dust cover, which flips out to the left of the lens, is open. This approximated color image was created using the camera's violet and infrared filters as blue and red.

  13. Study on Hot Gases Flow in Case of Fire in a Road Tunnel

    Directory of Open Access Journals (Sweden)

    Aleksander Król

    2018-03-01

    Full Text Available This paper presents the results of hot smoke tests, which were conducted in a real road tunnel. The tunnel is located within the expressway S69 in southern Poland between cities Żywiec and Zwardoń. Its common name is Laliki tunnel. It is a bidirectional non-urban tunnel. The length of the tunnel is 678 m and it is inclined by 4%. It is equipped with the longitudinal ventilation system. Two hot smoke tests have been carried out according to Australian Standard AS 4391-1999. Hot smoke tests corresponded to a Heat Release Rate (HRR equal to respectively 750 kW and 1500 kW. The fire source was located in the middle of the road lane imitating an initial phase of a car fire (respectively 150 m and 265 m from S portal. The temperature distribution was recorded during both tests using a set of fourteen thermocouples that were mounted at two stand poles located at the main axis of the tunnel on windward. The stand poles were placed at distances of 5 m and 10 m. The recorded data were applied to validate a numerical model, which was built and solved using Ansys Fluent. The calculated temperature distribution matched the measured values.

  14. Prediction Study of Tunnel Collapse Risk in Advance based on Efficacy Coefficient Method and Geological Forecast

    Directory of Open Access Journals (Sweden)

    QIU Daohong

    2014-08-01

    Full Text Available Collapse is one of the most common accidents in underground constructions. Risk evaluation is the method of measuring the risk of chamber collapse. To ensure the safety of construction, a risk evaluation model of tunnel collapse based on an efficacy coefficient method and geological prediction was put forward. Based on the comprehensive analysis of collapse factors, five main factors including rock uniaxial compressive strength, surrounding rock integrated coefficient, state of discontinuous structural planes, the angle between tunnel axis and major structural plane and underground water were chosen as the risk evaluation indices of tunnel collapse. The evaluation indices were quantitatively described by using TSP203 system and core-drilling to establish the risk early warning model of tunnel collapse based on the basic principle of the efficacy coefficient method. The model established in this research was applied in the collapse risk recognition of Kiaochow Bay subsea tunnel in Qingdao, China. The results showed that the collapse risk recognition method presents higher prediction accuracy and provided a new idea for the risk prediction of tunnel collapse.

  15. Quantum tunneling with friction

    Science.gov (United States)

    Tokieda, M.; Hagino, K.

    2017-05-01

    Using the phenomenological quantum friction models introduced by P. Caldirola [Nuovo Cimento 18, 393 (1941), 10.1007/BF02960144] and E. Kanai [Prog. Theor. Phys. 3, 440 (1948), 10.1143/ptp/3.4.440], M. D. Kostin [J. Chem. Phys. 57, 3589 (1972), 10.1063/1.1678812], and K. Albrecht [Phys. Lett. B 56, 127 (1975), 10.1016/0370-2693(75)90283-X], we study quantum tunneling of a one-dimensional potential in the presence of energy dissipation. To this end, we calculate the tunneling probability using a time-dependent wave-packet method. The friction reduces the tunneling probability. We show that the three models provide similar penetrabilities to each other, among which the Caldirola-Kanai model requires the least numerical effort. We also discuss the effect of energy dissipation on quantum tunneling in terms of barrier distributions.

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

    Directory of Open Access Journals (Sweden)

    Saroj Kumar Ojha

    2015-01-01

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

  17. High resolution transmission electron microscopic study of nanoporous carbon consisting of curved single graphite sheets

    International Nuclear Information System (INIS)

    Bourgeois, L.N.; Bursill, L.A.

    1997-01-01

    A high resolution transmission electron microscopic study of a nanoporous carbon rich in curved graphite monolayers is presented. Observations of very thin regions. including the effect of tilting the specimen with respect to the electron beam, are reported. The initiation of single sheet material on an oriented graphite substrate is also observed. When combined with image simulations and independent measurements of the density (1.37g cm -3 ) and sp 3 /sp 2 +sp 2 bonding fraction (0.16), these observations suggest that this material is a two phase mixture containing a relatively low density aggregation of essentially capped single shells like squat nanotubes and polyhedra, plus a relatively dense 'amorphous' carbon structure which may be described using a random-Schwarzite model. Some negatively-curved sheets were also identified in the low density phase. Finally, some discussion is offered regarding the growth mechanisms responsible for this nanoporous carbon and its relationship with the structures of amorphous carbons across a broad range of densities, porosities and sp 3 /sp 2 +sp 3 bonding fractions

  18. Electron microscopic radioautographic studies on macromolecular synthesis in mitochondria of animal cells in aging

    Energy Technology Data Exchange (ETDEWEB)

    Nagata, Tetsuji, E-mail: nagata@kowagakuen.ac.j [Shinshu Univ. School of Medicine, Matsumoto (Japan). Dept. of Anatomy and Cell Biology

    2010-07-01

    Study aging changes of intramitochondrial DNA, RNA, protein synthesis of mouse organs during the development and aging, 30 groups of developing and aging mice (3 individuals each), from fetal day 19 to postnatal newborn at day 1, 3, 9, 14 and adult at month 1, 2, 6, 12 to 24, were injected with either {sup 3}H-thymidine, {sup 3}H-uriidine, or {sup 3}H-leucine, sacrificed 1 h later and liver, adrenal, lung and testis tissues observed by electron microscopic radioautography. Accordingly, numbers of mitochondria per cell profile area, numbers of labeled mitochondria and the mitochondrial labeling index labeled with {sup 3}H-labeled precursors showing DNA, RNA, protein synthesis in these cells (hepatocytes, 3 zones of the adrenal cortices - zona glomerulosa, fasciculata and reticularis -, adrenal medullary cells, pulmonary cells and testis cells) were counted per cells and compared among the respective developing and aging groups. The numbers of mitochondria in these cells increased from fetal day 19 to postnatal month 1 and 2. However, the numbers of labeled mitochondria and the labeling indices of intramitochondrial DNA, RNA, protein syntheses incorporating the {sup 3}H-labeled precursors in the described tissue cells increased from fetal day 19 to postnatal month 1 and decreased to month 24. These data support that the activity of intramitochnodrial DNA, RNA, protein syntheses in cells of these tissues increased and decreased by development and aging in mice. The intramitochondrial DNA, RNA and protein syntheses in some other organs were also reviewed and discussed. (author)

  19. Microscopic Study of Skin Diseases in Horses from the Bogota Savanna, Colombia

    Directory of Open Access Journals (Sweden)

    Iovana Castellanos Londoño

    2014-06-01

    Full Text Available Horses hold third place in number of cases of skin disease after cats and dogs; however, there is little information about the demographic aspects of dermatological diseases in this species in Colombia. The purpose of this work was to carry out a preliminary study in order to determine the dermatological diseases that affect horses in the Bogota Savanna, through biopsy, skin scraping and trichogram, in order to approach the diagnosis and thus to establish therapeutic and prophylactic measures that benefit the animal’s health and productivity in commercial farms. Thirty-nine skin biopsies, thirty-nine cutaneous scraping and thirtyseven samples of hairy peel from horses with some kind of skin disease were received, all of which were processed by the Histopathology Laboratory from La Salle University. The inflammatory injuries were sorted taking into account the histological patterns of inflammatory skin disease and tumors, according to the classification by the World Health Organization (WHO. Allergic dermatitis was the most common pathology (46% and neoplasia was observed in 13% of the cases; fungal spores in ectothrix position were found in 10% of the cutaneous scrapes. Mites of the type Psoroptes spp were identified in one of the trichograms. This is the first report of microscopic diagnosis of skin diseases of horses in the country with the goal of contributing with the demographic knowledge of skin diseases in the Bogota Savanna.

  20. Atom probe field ion microscope study of the range and diffusivity of helium in tungsten

    International Nuclear Information System (INIS)

    Wagner, A.

    1978-08-01

    A time-of-flight (TOF) atom-probe field-ion microscope (FIM) specifically designed for the study of defects in metals is described. With this automated system 600 TOF min -1 can be recorded and analyzed. Performance tests of the instrument demonstrated that (1) the seven isotopes of molybdenum and the five isotopes of tungsten can be clearly resolved; and (2) the concentration and spatial distribution of all constitutents present at levels greater than 0.05 at. % in a W--25 at. % Re, Mo--1.0 at. % Ti, Mo--1.0 at. % Ti--0.08 at. % Zr (TZM), a low swelling stainless steel (LS1A) and a metallic glass (Metglas 2826) can be measured. The effect of the rate of field evaporation on the quantitative atom probe analysis of a Mo--1.0 at. % Ti alloy and a Mo--1.0 at. % Ti--0.08 at. % Zr alloy was investigated. As the field evaporation rate increased the measured Ti concentration was found to also increase. A simple qualitative model was proposed to explain the observation. The spatial distribution of titanium in a fast neutron irradiated Mo--1.0 at. % Ti alloy has been investigated. No evidence of Ti segregation to the voids was detected nor has any evidence of significant resolution of Ti from the TiC precipitates been detected. A small amount of segregation of carbon to a void was detected

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

    Science.gov (United States)

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

    2015-01-01

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

  2. Transmission electron microscopical study of teenage crown dentin on the nanometer scale

    International Nuclear Information System (INIS)

    Panfilov, Peter; Kabanova, Anna; Guo, Jinming; Zhang, Zaoli

    2017-01-01

    Statement of significance: This is the first transmission electron microscopic study of teenage crown dentin on the nanometer scale. Samples for TEM were prepared by mechanical thinning and chemical polishing that allowed obtaining the electron transparent foils. It was firstly shown that human dentin possesses the layered morphology: the layers are oriented normally to the main axis of a tooth and have the thickness of ~ 50 nm. HA inorganic phase of teenage crown dentin is in the amorphous state. The cellular structure, which was formed from collagen fibers (diameter is ~ 5 nm), are observed near DEJ region in teenage dentin, whereas bioorganic phase of teenage crown dentin near the pulp camera does not contain the collagen fibers. Cracks in dentin thin foils have sharp tips, but big angles of opening (~ 30 ° ) with plastic zone ahead crack tip. It means that young crown human dentin exhibits ductile or viscous-elastic fracture behavior on the nanometer scale. - Highlights: • Dentin has layered morphology. • Mineral component of dentin is in amorphous state. • Collagen fibers form cellular structure in dentin. • Cracks in dentin behave by elastic-plastic manner.

  3. High resolution transmission electron microscopic study of nanoporous carbon consisting of curved single graphite sheets

    Energy Technology Data Exchange (ETDEWEB)

    Bourgeois, L.N.; Bursill, L.A.

    1997-12-31

    A high resolution transmission electron microscopic study of a nanoporous carbon rich in curved graphite monolayers is presented. Observations of very thin regions. including the effect of tilting the specimen with respect to the electron beam, are reported. The initiation of single sheet material on an oriented graphite substrate is also observed. When combined with image simulations and independent measurements of the density (1.37g cm {sup -3}) and sp{sup 3}/sp{sup 2}+sp{sup 2} bonding fraction (0.16), these observations suggest that this material is a two phase mixture containing a relatively low density aggregation of essentially capped single shells like squat nanotubes and polyhedra, plus a relatively dense `amorphous` carbon structure which may be described using a random-Schwarzite model. Some negatively-curved sheets were also identified in the low density phase. Finally, some discussion is offered regarding the growth mechanisms responsible for this nanoporous carbon and its relationship with the structures of amorphous carbons across a broad range of densities, porosities and sp{sup 3}/sp{sup 2}+sp{sup 3} bonding fractions. 29 refs., 8 figs., 2 tabs.

  4. Microscopic Analysis and Quality Assessment of Induced Sputum From Children With Pneumonia in the PERCH Study.

    Science.gov (United States)

    Murdoch, David R; Morpeth, Susan C; Hammitt, Laura L; Driscoll, Amanda J; Watson, Nora L; Baggett, Henry C; Brooks, W Abdullah; Deloria Knoll, Maria; Feikin, Daniel R; Kotloff, Karen L; Levine, Orin S; Madhi, Shabir A; O'Brien, Katherine L; Scott, J Anthony G; Thea, Donald M; Ahmed, Dilruba; Awori, Juliet O; DeLuca, Andrea N; Ebruke, Bernard E; Higdon, Melissa M; Jorakate, Possawat; Karron, Ruth A; Kazungu, Sidi; Kwenda, Geoffrey; Hossain, Lokman; Makprasert, Sirirat; Moore, David P; Mudau, Azwifarwi; Mwaba, John; Panchalingam, Sandra; Park, Daniel E; Prosperi, Christine; Salaudeen, Rasheed; Toure, Aliou; Zeger, Scott L; Howie, Stephen R C

    2017-06-15

    It is standard practice for laboratories to assess the cellular quality of expectorated sputum specimens to check that they originated from the lower respiratory tract. The presence of low numbers of squamous epithelial cells (SECs) and high numbers of polymorphonuclear (PMN) cells are regarded as indicative of a lower respiratory tract specimen. However, these quality ratings have never been evaluated for induced sputum specimens from children with suspected pneumonia. We evaluated induced sputum Gram stain smears and cultures from hospitalized children aged 1-59 months enrolled in a large study of community-acquired pneumonia. We hypothesized that a specimen representative of the lower respiratory tract will contain smaller quantities of oropharyngeal flora and be more likely to have a predominance of potential pathogens compared to a specimen containing mainly saliva. The prevalence of potential pathogens cultured from induced sputum specimens and quantity of oropharyngeal flora were compared for different quantities of SECs and PMNs. Of 3772 induced sputum specimens, 2608 (69%) had 25 PMNs per LPF, measures traditionally associated with specimens from the lower respiratory tract in adults. Using isolation of low quantities of oropharyngeal flora and higher prevalence of potential pathogens as markers of higher quality, 25 PMNs per LPF) was the microscopic variable most associated with high quality of induced sputum. Quantity of SECs may be a useful quality measure of induced sputum from young children with pneumonia. © The Author 2017. Published by Oxford University Press for the Infectious Diseases Society of America.

  5. Microscopic studies of electric dipole resonances in 1p shell nuclei

    International Nuclear Information System (INIS)

    Kissener, H.R.; Rotter, I.; Goncharova, N.G.

    1986-05-01

    Recent data on total and partial photonuclear cross sections in the GDR region of the nuclei 6 Li to 16 O are compared with theoretical predictions, mostly from shell model and continuum shell model studies. The influence of the size of the configuration space, of the adopted residual interaction and of the continuous spectrum on the isovector E1 response is discussed to some detail. The observed trends of the localization, the shape and width, the isospin and the configurational structure of the GDR with increasing 1p shell occupation are related to the microscopic structure of the nuclear ground state. Particular attention is given to the partial (γ, N/sub i/) disintegration channels. Complex-particle emission and isospin mixing in the nuclear states are discussed for a few cases. An attempt is made to bring some systematics also in the evidence on excited-state giant resonances through the 1p shell region. The photonuclear GDR is compared with other giant multipole excitations, mostly for the example of the 14 C nucleus. (author)

  6. An operational study comparing microscopes and staining variations for tuberculosis LED FM.

    Science.gov (United States)

    Van Deun, A; Aung, K J M; Khan, M H; de Jong, B C; Gumusboga, M; Hossain, M A

    2014-08-01

    Tuberculosis control projects, Damien Foundation Bangladesh. To compare transmitted fluorescence (Olympus CX21™/FRAEN FluoLED™) with epi-fluorescence (Zeiss Primostar iLED™) light-emitting diode microscopes (LED-FM) and various auramine staining and destaining/counterstaining techniques for the detection of acid-fast bacilli. Multicentre blinded reading of routine smears on both types of microscopes using different staining techniques in multiple phases. LED-FM rechecking of discordant series with and without restaining to calculate operating characteristics. Among 64 874 smears, both instruments detected 9.6% positives. Compared to the standard technique, the stronger auramine-O formulation did not perform better. Thiazine red counterstaining tended to yield more false-positive as well as false-negative errors. Combined destaining/counterstaining (sensitivity 93%, positive predictive value [PPV] 98%) proved significantly less effective. Both destaining with 1% hydrochloric acid (HCl) and 10% alcohol and the standard 0.5% HCl and 70-95% alcohol were equally accurate (sensitivity 95-96%, PPV 99%). The sturdiness of the microscopes in field conditions was sub-optimal: only 5/16 instruments did not break down. Both microscopes performed equally well. The standard staining technique is as good as the more complicated and expensive variations. A destaining solution containing only 10% alcohol works perfectly well. The inferior quality of LED-FM microscope components is an obstacle to FM expansion.

  7. Single-Incision Carpal Tunnel Release and Distal Radius Open Reduction and Internal Fixation: A Cadaveric Study.

    Science.gov (United States)

    Gaspar, Michael P; Sessions, Blane A; Dudoussat, Bryan S; Kane, Patrick M

    2016-08-01

    The safety of surgical approaches for single- versus double-incision carpal tunnel release in association with distal radius open reduction and internal fixation remains controversial. The purpose of this study was to identify critical structures to determine if a single-incision extension of the standard flexor carpi radialis (FCR) approach can be performed safely. Nine cadaveric arms with were dissected under loupe magnification, utilizing a standard FCR approach. After the distal radius exposure was complete, the distal portion of the FCR incision was extended to allow release of the carpal tunnel. Dissection of critical structures was performed, including the recurrent thenar motor branch of the median nerve, the palmar cutaneous branch of the median nerve (PCBm), the palmar carpal and superficial palmar branches of the radial artery, and proximally the median nerve proper. The anatomic relationship of these structures relative to the surgical approach was recorded. Extension of the standard FCR approach as described in this study did not damage any critical structure in the specimens dissected. The PCBm was noted to arise from the radial side of the median nerve an average of 6.01cm proximal to the proximal edge of the transverse carpal ligament. The PCBm became enveloped in the layers of the antebrachial fascia and the transverse carpal ligament at the incision site, protecting it from injury. The recurrent motor branch of the median nerve, branches of the radial artery and the median nerve proper were not at risk during extension of the FCR approach to release the carpal tunnel. Extension of the standard FCR approach to include carpal tunnel release can be performed with minimal risk to the underlying structures. This exposure may offer benefits in both visualization and extent of carpal tunnel release.

  8. Comprehensive study of unexpected microscope condensers formed in sample arrangements commonly used in optical microscopy.

    Science.gov (United States)

    Desai, Darshan B; Aldawsari, Mabkhoot Mudith S; Alharbi, Bandar Mohammed H; Sen, Sanchari; Grave de Peralta, Luis

    2015-09-01

    We show that various setups for optical microscopy which are commonly used in biomedical laboratories behave like efficient microscope condensers that are responsible for observed subwavelength resolution. We present a series of experiments and simulations that reveal how inclined illumination from such unexpected condensers occurs when the sample is perpendicularly illuminated by a microscope's built-in white-light source. In addition, we demonstrate an inexpensive add-on optical module that serves as an efficient and lightweight microscope condenser. Using such add-on optical module in combination with a low-numerical-aperture objective lens and Fourier plane imaging microscopy technique, we demonstrate detection of photonic crystals with a period nearly eight times smaller than the Rayleigh resolution limit.

  9. Typical Underwater Tunnels in the Mainland of China and Related Tunneling Technologies

    Directory of Open Access Journals (Sweden)

    Kairong Hong

    2017-12-01

    Full Text Available In the past decades, many underwater tunnels have been constructed in the mainland of China, and great progress has been made in related tunneling technologies. This paper presents the history and state of the art of underwater tunnels in the mainland of China in terms of shield-bored tunnels, drill-and-blast tunnels, and immersed tunnels. Typical underwater tunnels of these types in the mainland of China are described, along with innovative technologies regarding comprehensive geological prediction, grouting-based consolidation, the design and construction of large cross-sectional tunnels with shallow cover in weak strata, cutting tool replacement under limited drainage and reduced pressure conditions, the detection and treatment of boulders, the construction of underwater tunnels in areas with high seismic intensity, and the treatment of serious sedimentation in a foundation channel of immersed tunnels. Some suggestions are made regarding the three potential great strait-crossing tunnels—the Qiongzhou Strait-Crossing Tunnel, Bohai Strait-Crossing Tunnel, and Taiwan Strait-Crossing Tunnel—and issues related to these great strait-crossing tunnels that need further study are proposed. Keywords: Underwater tunnel, Strait-crossing tunnel, Shield-bored tunnel, Immersed tunnel, Drill and blast

  10. Exponential size-dependent tunability of strain on the transport behavior in ZnO tunnel junctions: an ab initio study.

    Science.gov (United States)

    Zhu, Jia; Chen, W J; Zhang, G H; Zheng, Yue

    2015-10-14

    It is an interesting issue if the transport behavior of a piezoelectric tunnel junction is sensitive to external strain or stress, and it implies a prospect for developing novel mechanical sensors, transducers, piezotronic devices, etc. Many studies paid attention to this issue, yet how the strain and stress tunable transport behavior of a tunnel junction depends on the barrier thickness is still rarely known. Using the first principles calculations, we investigate the size-dependent and strain-tunable transport behavior in the tunnel junctions. It was confirmed that external strain has strong control over the transport properties of ZnO tunnel junctions, with several times amplification of tunnel conductance obtained by strain reversal. More importantly, the conductance amplification by strain reversal exponentially changes with the barrier thickness, indicating the size-dependent strain tunability of the transport behavior. The electrostatic quantities (i.e., built-in field, depolarization field, polarization, interfacial dipoles and potential barrier) and the transport properties of tunnel junctions were comprehensively analyzed to reveal the relationships between these quantities and their size dependence. The exponential size-dependence of strain tunable transport behavior in ZnO tunnel junctions is attributed to the linear change in the potential barrier with the barrier thickness. Our simulations provide an insight of how to maximize the strain tunability of transport behavior of piezoelectric tunnel junctions by thickness design and strain engineering.

  11. Microscopic study of weathering of white Flemish stone from the monumental Church of Our Lady in Breda, The Netherlands

    NARCIS (Netherlands)

    Larbi, J.A.; Hees, R.P.J. van; Naldini, S.

    2003-01-01

    This paper deals with the use of an integrated microscopic method to assist in the investigation of the causes and the extent of decay of the stones and ornaments in the gothic Clurch of Out Lady in Breda, The Netherlands. The purpose of the study was to determine whether conservation measures were

  12. Aeroelastic Uncertainty Quantification Studies Using the S4T Wind Tunnel Model

    Science.gov (United States)

    Nikbay, Melike; Heeg, Jennifer

    2017-01-01

    This paper originates from the joint efforts of an aeroelastic study team in the Applied Vehicle Technology Panel from NATO Science and Technology Organization, with the Task Group number AVT-191, titled "Application of Sensitivity Analysis and Uncertainty Quantification to Military Vehicle Design." We present aeroelastic uncertainty quantification studies using the SemiSpan Supersonic Transport wind tunnel model at the NASA Langley Research Center. The aeroelastic study team decided treat both structural and aerodynamic input parameters as uncertain and represent them as samples drawn from statistical distributions, propagating them through aeroelastic analysis frameworks. Uncertainty quantification processes require many function evaluations to asses the impact of variations in numerous parameters on the vehicle characteristics, rapidly increasing the computational time requirement relative to that required to assess a system deterministically. The increased computational time is particularly prohibitive if high-fidelity analyses are employed. As a remedy, the Istanbul Technical University team employed an Euler solver in an aeroelastic analysis framework, and implemented reduced order modeling with Polynomial Chaos Expansion and Proper Orthogonal Decomposition to perform the uncertainty propagation. The NASA team chose to reduce the prohibitive computational time by employing linear solution processes. The NASA team also focused on determining input sample distributions.

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

    Energy Technology Data Exchange (ETDEWEB)

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

    1992-07-01

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

  14. Histological changes in kidneys of adult rats treated with Monosodium glutamate: A light microscopic study

    Directory of Open Access Journals (Sweden)

    Singh BR, Ujwal Gajbe, Anil Kumar Reddy, Vandana Kumbhare

    2015-01-01

    Full Text Available Introduction: Monosodium Glutamate (MSG, which is chemically known as AJI-NO-MOTO also familiar as MSG in routine life. MSG is always considered to be a controversial food additive used in the world. It is a natural excitatory neurotransmitter, helps in transmitting the fast synaptic signals in one third of CNS. Liver and kidney play a crucial role in metabolism as well as elimination of MSG from the body. Present study is to detect structural changes in adult rat kidney tissue treated with MSG; observations are done with a light microscope. Materials & Methods: The study was conducted in the department of Anatomy, J.N.M.C, Sawangi (M Wardha. Thirty (30 adult Wistar rats (2-3 months old weighing about (200 ± 20g were used in the current study, animals were divided into three groups (Group – A, B, C. Group A: Control, Group B: 3 mg /gm body weight, Group C: 6 mg /gm body weight, MSG were administered orally daily for 45 days along with the regular diet. Observations & Results: The Mean values of animals weight at the end of experiment (46th day respectively were 251.2 ± 13, 244.4 ± 19.9 and 320 ± 31.1. Early degenerative changes like, Glomerular shrinkage (GSr, loss of brush border in proximal convoluted tubules and Cloudy degeneration was observed in sections of kidney treated with 3 mg/gm body weight of MSG. Animals treated with 6 mg/gm body weight of MSG showed rare changes like interstitial chronic inflammatory infiltrate with vacuolation in some of the glomeruli, and much glomerular shrinkage invaginated by fatty lobules. Conclusion: The effects of MSG on kidney tissues of adult rats revealed that the revelatory changes are directly proportional to the doses of MSG.

  15. Microscopic Theory of Transconductivity

    Directory of Open Access Journals (Sweden)

    A. P. Jauho

    1998-01-01

    Full Text Available Measurements of momentum transfer between two closely spaced mesoscopic electronic systems, which couple via Coulomb interaction but where tunneling is inhibited, have proven to be a fruitful method of extracting information about interactions in mesoscopic systems. We report a fully microscopic theory for transconductivity σ12, or, equivalently, momentum transfer rate between the system constituents. Our main formal result expresses the transconductivity in terms of two fluctuation diagrams, which are topologically related, but not equivalent to, the Azlamazov-Larkin and Maki-Thompson diagrams known for superconductivity. In the present paper the magnetic field dependence of σ12 is discussed, and we find that σ12(B is strongly enhanced over its zero field value, and it displays strong features, which can be understood in terms of a competition between density-of-states and screening effects.

  16. Wind tunnel study of a vertical axis wind turbine in a turbulent boundary layer flow

    Science.gov (United States)

    Rolin, Vincent; Porté-Agel, Fernando

    2015-04-01

    Vertical axis wind turbines (VAWTs) are in a relatively infant state of development when compared to their cousins the horizontal axis wind turbines. Very few studies have been carried out to characterize the wake flow behind VAWTs, and virtually none to observe the influence of the atmospheric boundary layer. Here we present results from an experiment carried out at the EPFL-WIRE boundary-layer wind tunnel and designed to study the interaction between a turbulent boundary layer flow and a VAWT. Specifically we use stereoscopic particle image velocimetry to observe and quantify the influence of the boundary layer flow on the wake generated by a VAWT, as well as the effect the VAWT has on the boundary layer flow profile downstream. We find that the wake behind the VAWT is strongly asymmetric, due to the varying aerodynamic forces on the blades as they change their position around the rotor. We also find that the wake adds strong turbulence levels to the flow, particularly on the periphery of the wake where vortices and strong velocity gradients are present. The boundary layer is also shown to cause greater momentum to be entrained downwards rather than upwards into the wake.

  17. An experimental study of furan adsorption and decomposition on vicinal palladium surfaces using scanning tunneling microscopy

    Science.gov (United States)

    Loui, A.; Chiang, S.

    2018-04-01

    The intact adsorption and decomposition of furan (C4H4O) on vicinal palladium surfaces with (111)-oriented terraces has been studied by scanning tunneling microscopy (STM) over a range of temperatures. STM images at 225 K show that furan molecules lie flat and prefer to adsorb at upper step edges. At 225 K, furan molecules adsorbed on "narrow" terraces of 20 to 45 Å in width appear to diffuse more readily than those adsorbed on "wide" terraces of 160 to 220 Å. A distinct population of smaller features appears in STM images on "narrow" terraces at 288 K and on "wide" terraces at 415 K and is identified with the C3H3 decomposition product, agreeing with prior studies which demonstrated that furan dissociates on Pd(111) to yield carbon monoxide (CO) and a C3H3 moiety in the 280 to 320 K range. Based on our direct visualization of this reaction using STM, we propose a spatial mechanism in which adsorption of furan at upper step edges allows catalysis of the dissociation, followed by diffusion of the product to lower step edges.

  18. A prospective study of carpal tunnel syndrome: workplace and individual risk factors

    Science.gov (United States)

    Burt, Susan; Deddens, James A; Crombie, Ken; Jin, Yan; Wurzelbacher, Steve; Ramsey, Jessica

    2015-01-01

    Objectives To quantify the risk for carpal tunnel syndrome (CTS) from workplace physical factors, particularly hand activity level and forceful exertion, while taking into account individual factors including age, gender, body mass index (BMI), and pre-existing medical conditions. Methods Three healthcare and manufacturing workplaces were selected for inclusion on the basis of range of exposure to hand activity level and forceful exertion represented by their jobs. Each study participants job tasks were observed and evaluated ’ onsite and videotaped for further analysis, including frequency and duration of exertion and postural deviation. Individual health assessment entailed electrodiagnostic testing of median and ulnar nerves, physical examination and questionnaires at baseline with annual follow-up for 2 years. Results The incidence of dominant hand CTS during the study was 5.11 per 100 person-years (29 cases). Adjusted HRs for dominant hand CTS were as follows: working with forceful exertion ≥20% but job strain. Conclusions Workplace and individual risk factors both contribute to the risk for CTS. Time spent in forceful exertion can be a greater risk for CTS than obesity if the job exposure is high. Preventive workplace efforts should target forceful exertions. PMID:23788614

  19. A Monte Carlo study of macroscopic and microscopic dose descriptors for kilovoltage cellular dosimetry

    Science.gov (United States)

    Oliver, P. A. K.; Thomson, Rowan M.

    2017-02-01

    This work investigates how doses to cellular targets depend on cell morphology, as well as relations between cellular doses and doses to bulk tissues and water. Multicellular models of five healthy and cancerous soft tissues are developed based on typical values of cell compartment sizes, elemental compositions and number densities found in the literature. Cells are modelled as two concentric spheres with nucleus and cytoplasm compartments. Monte Carlo simulations are used to calculate the absorbed dose to the nucleus and cytoplasm for incident photon energies of 20-370 keV, relevant for brachytherapy, diagnostic radiology, and out-of-field radiation in higher-energy external beam radiotherapy. Simulations involving cell clusters, single cells and single nuclear cavities are carried out for cell radii between 5 and 10~μ m, and nuclear radii between 2 and 9~μ m. Seven nucleus and cytoplasm elemental compositions representative of animal cells are considered. The presence of a cytoplasm, extracellular matrix and surrounding cells can affect the nuclear dose by up to 13 % . Differences in cell and nucleus size can affect dose to the nucleus (cytoplasm) of the central cell in a cluster of 13 cells by up to 13 % (8 % ). Furthermore, the results of this study demonstrate that neither water nor bulk tissue are reliable substitutes for subcellular targets for incident photon energies  <50 keV: nuclear (cytoplasm) doses differ from dose-to-medium by up to 32 % (18 % ), and from dose-to-water by up to 21 % (8 % ). The largest differences between dose descriptors are seen for the lowest incident photon energies; differences are less than 3 % for energies ≥slant 90 keV. The sensitivity of results with regard to the parameters of the microscopic tissue structure model and cell model geometry, and the importance of the nucleus and cytoplasm as targets for radiation-induced cell death emphasize the importance of accurate models for cellular dosimetry studies.

  20. Study to optimize a disposal tunnel layout taking into account heterogeneous characteristics of the geological environment

    International Nuclear Information System (INIS)

    Suyama, Yasuhiro; Toida, Masaru; Yanagizawa, Koichi

    2007-01-01

    The geological environment has spatially heterogeneous characteristics with varied host rock types, fractures and so on. In this case the generic disposal tunnel layout, which has been designed by JNC, is not the most suitable for HLW disposal in Japan. The existence of spatially heterogeneous characteristics means that in the repository region there exist sub-regions that are more favorable from the perspective of long-term safety and ones that are less favorable. In order that the spatially heterogeneous environment itself may be utilized most effectively as an NBS, an alternative design of disposal tunnel layout is required. Focusing on the geological environment with spatially heterogeneous characteristics, the authors have developed an alternative design of disposal tunnel layout. The alternative design adopts an optimization approach using a 'variable disposal tunnel layout'. The optimization approach minimizes the number of locations where major water conducting fractures are intersected, and maximizes the number of emplacement locations for waste packages. This paper will outline the variable disposal tunnel layout and its applicability. (author)

  1. Self healing phenomena in concretes and masonry mortars: A microscopic study

    NARCIS (Netherlands)

    Nijland, T.G.; Larbi, J.A.; Hees, R.P.J. van; Lubelli, B.A.; Rooij, M.R. de

    2007-01-01

    A microscopic survey of over 1000 of samples of concrete and masonry mortars from structures in the Netherlands shows that, in practice, self healing occurs in historic lime and lime – puzzolana mortars, in contrast to modern cement bound concretes and mortars. Self healing may be effected by the

  2. Isocentric rotational performance of the Elekta Precise Table studied using a USB-microscope

    DEFF Research Database (Denmark)

    Riis, Hans L; Zimmermann, Sune J; Riis, Poul

    2010-01-01

    The isocentric three-dimensional performance of the Elekta Precise Table was investigated. A pointer was attached to the radiation head of the accelerator and positioned at the geometric rotational axis of the head. A USB-microscope was mounted on the treatment tabletop to measure the table...

  3. Transmission Electron Microscopic Study of Antibiotic Action on Klebsiella pneumoniae Biofilm

    OpenAIRE

    Zahller, Jeff; Stewart, Philip S.

    2002-01-01

    The penetration of ampicillin and ciprofloxacin through biofilms formed by Klebsiella pneumoniae was confirmed by transmission electron microscopic observation of antibiotic-affected cells at the distal edge of the biofilm. Because the bacteria nevertheless survived antibiotic treatment, some protective mechanism other than inadequate penetration must have been at work in the biofilm.

  4. Inelastic electron tunnelling spectroscopy—IV. A study of the formation of formic acid from atmospheric carbon dioxide and water within an Al—Aloxide—Pb tunnelling junction

    Science.gov (United States)

    Field, B. O.; Hart, R.; Lewis, D. M.

    1985-01-01

    Considerable confusion exists in the literature regarding the interpretation of peaks in the spectra of aluminium—aluminium oxide—lead tunnelling junctions doped with either water or water vapour. These peaks, which appear in the CH bend and stretch regions, have been variously assigned as trace organic impurities or as formic acid chemically produced within the tunnelling junction by a reaction between atmospheric carbon dioxide and the water dopant. The present work attempts to resolve this ambiguity by producing formic acid tunnelling spectra and comparing these with spectra produced from triply distilled water doped junctions. These spectra, which fingerprint exactly, have been assigned. Potential organic impurities in the water have been investigated by high resolution mass spectroscopy. The tunnelling spectrum of a junction electrode penetration doped with a suspension of calcium oxide in water has been produced and is assigned as calcium carbonate. It is suggested that a reaction takes place between calcium hydroxide and carbon dioxide adsorbed on the surface of the alumina to produce calcium carbonate. It is concluded that formic acid is produced within tunnelling junctions by a reaction between atmospheric carbon dioxide and water on the alumina surface.

  5. Mechanical and thermo-mechanical analyses of the tapered plug for plugging of deposition tunnels. A feasibility study

    Energy Technology Data Exchange (ETDEWEB)

    Faelth, Billy (Clay Technology AB, Lund (Sweden)); Gatter, Patrik (Vattenfall Power Consultant AB, Stockholm (Sweden))

    2009-09-15

    This report presents results from a study that was carried out in order to examine the applicability of the tapered plug concept for plugging of deposition tunnels in the deep repository for spent nuclear fuel. The report presents results from mechanical and thermo-mechanical models of the tapered plug. The models were analyzed with 3DEC. The models included a portion of a deposition tunnel and its intersection with a main tunnel. In the deposition tunnel, a tapered concrete plug was installed. The plug was subjected to the combined load from the swelling backfill material and from pore pressure inside the deposition tunnel. The thermo-mechanical effects due to the heat generation in the spent fuel were also included in the analyses. Generic material parameter values for the concrete were used. The following items were studied: - Stresses and displacements in the plug. - Shear stresses and shear displacements in the rock-concrete interface. - Stress additions in the rock due to the loads. The sensitivity of the results to changes of constitutive models, to changes of the plug geometry and to pore water pressure in the rock-concrete interface was examined. The results indicate that the displacements in the plug will be within reasonable ranges but the stresses may locally be high enough that they exceed acceptable levels. However, they can be reduced by choice of advantageous plug geometry and by having a good rock-concrete bond. The results also show that the stress additions in the rock due to the thermal load may yield stresses that locally exceed the spalling strength of the rock. At most locations, however, the rock stresses will amount at lower levels. It was concluded that, with choice of an appropriate design, the tapered plug seems to be an applicable concept for plugging of deposition tunnels. It was also concluded that further studies of the tapered plug concept should use material properties parameter values for low-pH concrete. Further, they should also

  6. Braze alloy process and strength characterization studies for 18 nickel grade 200 maraging steel with application to wind tunnel models

    Science.gov (United States)

    Bradshaw, James F.; Sandefur, Paul G., Jr.; Young, Clarence P., Jr.

    1991-01-01

    A comprehensive study of braze alloy selection process and strength characterization with application to wind tunnel models is presented. The applications for this study include the installation of stainless steel pressure tubing in model airfoil sections make of 18 Ni 200 grade maraging steel and the joining of wing structural components by brazing. Acceptable braze alloys for these applications are identified along with process, thermal braze cycle data, and thermal management procedures. Shear specimens are used to evaluate comparative shear strength properties for the various alloys at both room and cryogenic (-300 F) temperatures and include the effects of electroless nickel plating. Nickel plating was found to significantly enhance both the wetability and strength properties for the various braze alloys studied. The data are provided for use in selecting braze alloys for use with 18 Ni grade 200 steel in the design of wind tunnel models to be tested in an ambient or cryogenic environment.

  7. Macro and microscopic study of avian tuberculosis at Savannah´s Bogotá zoo

    Directory of Open Access Journals (Sweden)

    Rafael Neira Rairán

    2006-12-01

    Full Text Available Avian tuberculosis diagnosis was made in captive wild birds (Burhinus bistriatus and Porphyrula martinica from a zoo park at Sabana de Bogotá (Colombia. Based on this diagnosis, a surveillance approach was designed in order to demonstrate whether or not a focus of tuberculosis infection caused by Micobacterium avium was present at this zoo with the purpose to identify a possible hazard to prevent the infection of other bird population, visitors and workers of the park. Clinical, morphological (gross and microscopic are described in this article, but microbiological (culture in specific media, epidemiological (DPP and molecular (PCR studies, will be shown in other journal. In this work animals were organized en three different groups as follow: Five Hy line Brown chicken tuberculosis free coming from a commercial farm (sentinel group. A mixed group birds (102 animals from the pens around the primary focus (28 dukes, 25 “guacamayas”, 26 parrots and 23 rapacious birds, (highest risk group. Five birds within the pen in which the diagnosis was made (contaminated birds group. It was demonstrated granulomatous lesions in animals from the sentinel group as well as in those from the pen in which the first diagnosis was made. Lesions were founded in liver, spleen, lungs, kidneys, intestines and in one case in the white matter and leptomeniges of the spinal cord were affected. Ziehl – Neelsen positive rods were identified in all the affected tissues. No tuberculosis lesions were found in animals caged in neighborhood pens. It was concluded that there is an infectious focus of tuberculosis (micobacteriosis caused by M. avium in the zoo, but the focus is located only in one pen and this focus could represent a critical risk of infection with M. avium for some of the birds within the zoo, wild and eventually commercials birds and the human beings as well. It is recommended that prevention, control and eradication measurements have to be made to prevent

  8. Determination and microscopic study of incipient defects in irradiated power reactor fuel rods. Final report

    International Nuclear Information System (INIS)

    Pasupathi, V.; Perrin, J.S.; Roberts, E.

    1978-05-01

    This report presents the results of nondestructive and destructive examinations carried out on the Point Beach-1 (PWR) and Dresden-3 (BWR) candidate fuel rods selected for the study of pellet-clad interaction (PCI) induced incipient defects. In addition, the report includes results of examination of sections from Oskarshamn-1 (BWR) fuel rods. Eddy current examination of Point Beach-1 rods showed indications of possible incipient defects in the fuel rods. The profilometry and the gamma scan data also indicated that the source of the eddy current indications may be incipient defects. No failed rods or rods with incipient failure were found in the sample from Point Beach-1. Despite the lack of success in finding incipient defects and filed rods, the mechanism for fuel rod failures in Point Beach-1 is postulated to be PCI-related, with high startup rates and fuel handling being the key elements. Nine out of the 10 candidate fuel rods from Dresden-3 (BWR) were failed, and all the failed rods had leaked water so that the initial mechanism was observed. Examination of clad inner surfaces of the specimens from failed and unfailed rods showed fuel deposits of widely varying appearance. The deposits were found to contain uranium, cesium, and tellurium. Transmission electron microscopy of clad specimens showed evidence of microscopic strain. Metallographic examination of fuel pellets from the peak transient power location showed extensive grain boundary separation and axial movement of the fuel indicative of rapid release of fission products. Examination of Oskarshamn clad specimens did not show any stress corrosion crack (SCC) type defects. The defects found in the examinations appear to be related to secondary hydriding. The clad inner surface of the Oskarshamn specimens also showed uranium-rich deposits of varying features

  9. Epidemiological, microbiological & electron microscopic study of a cholera outbreak in a Kolkata slum community.

    Science.gov (United States)

    Sur, Dipika; Sarkar, B L; Manna, B; Deen, J; Datta, S; Niyogi, S K; Ghosh, A N; Deb, A; Kanungo, S; Palit, A; Bhattacharya, S K

    2006-01-01

    Epidemics of cholera caused by Vibrio cholerae O1 or O139 have been reported from different parts of India. Factors such as unsafe water supply, poor environmental sanitation, indiscriminate defaecation and lack of personal hygiene are mainly responsible for continued transmission of this disease. We report here epidemiological and microbiological findings of a localized outbreak of cholera, which occurred during March and April 2004 in the eastern part of Kolkata city. The affected slum area has a population of 4409, predominantly muslims. Patients suffering from acute watery diarrhoea attended the health outposts organized by National Institute of Cholera and Enteric Diseases, Kolkata and International Vaccine Institute, South Korea as part of a routine surveillance programme at the locality as well as the emergency medical camp organized by the Kolkata Municipal Corporation. Stool and water samples were collected and tested for diarrhoeagenic pathogens in the laboratory. Bacteriophages specific for V. cholerae were isolates and studied electron microscopically for morphology. A total of 89 diarrhoea cases were reported giving an attack rate of 2 per cent. V. cholerae O1 biotype ElTor, serotype Ogawa was isolated as a sole pathogen from 15 (15.8%) of 89 stool samples screened. Water samples (2 from tube wells, 3 from municipal taps and 1 from well) showed presence of coliform bacilli with high MPN (Most Probable Number) count. Bacteriophages specific to V. cholerae were isolated from 2 of 6 water samples examined. A leakage was detected in the main pipeline supplying drinking water to that area. The outbreak was caused by V. cholerae O1 (Ogawa) biotype ElTor. The presence of phages in the water samples was an additional indicator for V. cholerae contamination in this community. Occurrences of such outbreaks support vaccination against cholera as an alternative strategy.

  10. Electron microscopic studies on odontoblasts using 45Ca as the tracer

    International Nuclear Information System (INIS)

    Okamoto, Eiji

    1980-01-01

    In order to study the relationship between odontoblasts and inorganic salts, odontoblasts of 10-day old rats' incisions and molars were used. The animals were sacrificed 15 minutes, 30 minutes, 1 hour or 2 hours after 45 Ca administration to obtain the specimen. The specimens were processed for electron microscopic autoradiography. 15 minutes after 45 Ca administration, silver grains indicated 45 Ca uptake was already noted within the cells. 45 Ca was localized in the mitochondria, Golgi area, rough surfaced endoplasmic reticulum and partially within the karyoplasm. After 30 minutes' administration, the number of silver grains were generally increased as compared with the findings obtained after 15 minutes' administration. The localization was similar with those after 15 minutes' administration but some were found in the ribosomes and smooth surfaced endoplasmic reticulum with numerous silver grains within small vesicles derived from the Golgi apparatus as well. A movement of 45 Ca from the protruding part to the stroma was also noted. 1 hour after the administration, the number of silver grains were generally decreased, with a more pronounced movement towards stroma from the protruding part. The marked movement of silver grains was obtained onto the collagen fibers in the stroma. In the mitochondria, however, considerable number of silver grains were still seen. In this section, on the other hand, numerous silver grains were seen in the intercellular space, in addition to the pathway of intracellular route, indicating the Ca shift from outside of the cells. After 2 hours' 45 Ca administration, the tendency towards the decrease of the silver grains became more remarkable, the movement of 45 Ca via the extracellular pathway described above was also frequently found. (author)

  11. Electron microscopic studies of the matrix formation of hard tissue organized cell

    International Nuclear Information System (INIS)

    Chou, Ching-Eng

    1982-01-01

    In order to study the functions of odontoblast, especially on the matrix formation, odontoblasts of rats' incisor and molar teeth were used. The animals were sacrificed 5 minutes, 15 minutes, 30 minutes, 1 hour, 2 hours and 24 hours after 3 H-proline administration to obtain the specimen. The specimens were processed for electron microscopic autoradiography. The following results were obtained. 1. 5 minutes after 3 H-proline administration: Silver grains indicated 3 H-proline uptake were already noted within the cells and localized in the rough surfaced endoplasmic reticulum and surrounding ribosomes, partially within the karyoplasm. 2. 15 minutes after 3 H-proline administration: The number of silver grains were generally increased as compared with the findings obtained in 5 minutes. The localization moved to the Golgi apparatus and their surroundings. 3. 30 minutes after 3 H-proline administration: Silver grains obtained in Tome's fibers area and some in predentin. In this area granules derived from Golgi body were found. 4. 1 hour after 3 H-proline administration: The number of silver grains were generally decreased and more pronounced movement toward predentin, the marked movement of silver grains were obtained onto the collagen fibers and surroundings. 5. 2 hours after 3 H-proline administration: Silver grains moved to the calcified area and there collagen fibers became more remarkable. 6. 24 hours after 3 H-proline administration: No silver grains were founded in the odontoblast side but deposited in the predentin calcified area with stable condition. Based on the results of these observations, odontoblasts were shown to perform the function of synthesis, storage, transportation and control of collagen formation in addition to the role of matrix formation. (author)

  12. Defects in oxide surfaces studied by atomic force and scanning tunneling microscopy

    Directory of Open Access Journals (Sweden)

    Thomas König

    2011-01-01

    Full Text Available Surfaces of thin oxide films were investigated by means of a dual mode NC-AFM/STM. Apart from imaging the surface termination by NC-AFM with atomic resolution, point defects in magnesium oxide on Ag(001 and line defects in aluminum oxide on NiAl(110, respectively, were thoroughly studied. The contact potential was determined by Kelvin probe force microscopy (KPFM and the electronic structure by scanning tunneling spectroscopy (STS. On magnesium oxide, different color centers, i.e., F0, F+, F2+ and divacancies, have different effects on the contact potential. These differences enabled classification and unambiguous differentiation by KPFM. True atomic resolution shows the topography at line defects in aluminum oxide. At these domain boundaries, STS and KPFM verify F2+-like centers, which have been predicted by density functional theory calculations. Thus, by determining the contact potential and the electronic structure with a spatial resolution in the nanometer range, NC-AFM and STM can be successfully applied on thin oxide films beyond imaging the topography of the surface atoms.

  13. PIV-based study of the gliding osprey aerodynamics in a wind tunnel

    Science.gov (United States)

    Gurka, Roi; Liberzon, Alex; Kopp, Gregory; Kirchhefer, Adam; Weihs, Daniel

    2009-11-01

    The hunting flight of an osprey consists of periods where the bird glides while foraging for prey. High quality measurements of aerodynamics in this flight mode are needed in order to estimate the daily energy expenditure of the bird accurately. An experimental study of an osprey model in a wind tunnel (BLWTL, UWO) was performed in order to characterize the aerodynamic forces using particle image velocimetry (PIV). The model was a stuffed osprey with mechanical joints allowing control of the the wing (angle of attack, tilt) and tail orientation. Two-dimensional velocity realizations in the streamwise-normal plane were obtained simultaneously in the two fields of view: above the wing and in the wake of the wing. Mean and turbulent flow characteristics are presented as function of angle of attack based on measurements taken at 4 different angles of attack at three different locations over the wingspan. The main outcome is the accurate estimate of the drag from the measurements of momentum thickness in the turbulent boundary layer of the osprey wing. Moreover, the gradient of the momentum thickness method was applied to identify the separation point in the boundary layer. This estimate has been compared to the total drag calculated from measurements in the wake of the wing and with a theoretical prediction.

  14. Adsorption stages of O on Ru(0001) studied by means of scanning tunnelling microscopy

    CERN Document Server

    Meinel, K; Ammer, C; Beckmann, A; Neddermeyer, H

    1997-01-01

    The adsorption of O on Ru(0001) at a temperature of 400 K is studied in detail by means of scanning tunnelling microscopy (STM). With increasing O coverage, an ordered p(2x2) structure develops, followed by a p(2x1) structure. While the p(2x2) structure grows via island formation, the p(2x1) structure is abruptly formed by a disorder - order phase transition. After completion of the p(2x2) structure at a coverage of 0.25 ML, the surface develops a rough structure where the (2x2) units remain visible but appear with different heights. As the origin of this phenomenon, we propose additional O-O interactions and/or subsurface O due to the increase in O coverage. At coverages between 0.3 monolayer (ML) and 0.35 ML, different preformations of the p(2x1) structure are observed. First, small fragments of p(2x1) rows develop, which are randomly distributed over the surface and rotated by 120 deg. with respect to each other. They grow in one dimension and induce a criss-cross arrangement of linear chains of O atoms. T...

  15. Neutron microscope with refractive wedge

    International Nuclear Information System (INIS)

    Masalovich, S.V.

    1990-01-01

    A possibility of applying a refractive element in a mirror-neutron microscope using ultracold neutrons to reduce neutron aberrations is considered. Application of a refractive element in a neutron microscope with horizontal optical axis is studied. A scheme of neutron microscope with a refractive wedge is presented, evaluation of quartz wedge parameters is made. It is stressed that application of refractive elements in neutron microscopes facilitates aberration reduction in neutron-optical systems

  16. Comparative microscopic study of human and rat lungs after overexposure to welding fume.

    Science.gov (United States)

    Antonini, James M; Roberts, Jenny R; Schwegler-Berry, Diane; Mercer, Robert R

    2013-11-01

    Welding is a common industrial process used to join metals and generates complex aerosols of potentially hazardous metal fumes and gases. Most long-time welders experience some type of respiratory disorder during their time of employment. The use of animal models and the ability to control the welding fume exposure in toxicology studies have been helpful in developing a better understanding of how welding fumes affect health. There are no studies that have performed a side-by-side comparison of the pulmonary responses from an animal toxicology welding fume study with the lung responses associated with chronic exposure to welding fume by a career welder. In this study, post-mortem lung tissue was donated from a long-time welder with a well-characterized work background and a history of extensive welding fume exposure. To simulate a long-term welding exposure in an animal model, Sprague-Dawley rats were treated once a week for 28 weeks by intratracheal instillation with 2mg of a stainless steel, hard-surfacing welding fume. Lung tissues from the welder and the welding fume-treated rats were examined by light and electron microscopy. Pathological analysis of lung tissue collected from the welder demonstrated inflammatory cell influx and significant pulmonary injury. The poor and deteriorating lung condition observed in the welder examined in this study was likely due to exposure to very high levels of potentially toxic metal fumes and gases for a significant number of years due to work in confined spaces. The lung toxicity profile for the rats treated with welding fume was similar. For tissue samples from both the welder and treated rats, welding particle accumulations deposited and persisted in lung structures and were easily visualized using light microscopic techniques. Agglomerates of deposited welding particles mostly were observed within lung cells, particularly alveolar macrophages. Analysis of individual particles within the agglomerates showed that these

  17. Tracheal reconstruction by re-inforced Gore-Tex in esophageal submuscular tunneling: An experimental study

    Directory of Open Access Journals (Sweden)

    Hodjati Hossein

    2011-01-01

    Full Text Available Background: Tracheal reconstructions are aimed at rearranging or replacing parts of the tracheal tissue by different techniques. Here we introduce a new technique for tracheal reconstruction. Methods: In 10 adult dogs, after intubation with an endotracheal tube, a segment of trachea including seven tracheal rings was resected circumferentially. A submuscular tunnel was induced between mucosal and muscular layers of the adjacent esophagus lying right next to the trachea. The esophageal submuscular tunnel starts and ends exactly at the level of distal and proximal ends of tracheal resection, respectively. Inforced Gore-Tex passed through the esophageal submuscular tunnel the distal segment of trachea and end-to-end anastomosis were made between distal ends of Gore-Tex and trachea, then endotracheal tube removed and the same procedure was made for proximal ends of Gore-Tex and trachea. Afterward, the proximal and distal ends of the esophageal tunnel were approximated to proximal and distal tracheal parts over the anastomosis. Results: All dogs, except one due to anesthetic problem, survived and tolerated the operation; the first two dogs experienced postoperative fever, aspiration pneumonia, and died due to tracheoesophageal fistula. All survived animals were eating and barking well. We started to scarify dogs at least 6 and 12 weeks after operation for microscopy and pathologic examination. The Gore-Texes were patent and supported externally with fibrous connective tissue in esophageal tunneling, with in growth of respiratory epithelium on inner surfaces. Conclusion: Air tightness, good re-epithelialization, and relatively no limitation of esophageal length and no risk of luminal collapse are advantages of tracheal reconstruction by submuscular esophageal tunneling. This new method is worthy of further investigation, as it is technically feasible and easy to implement.

  18. Tracheal reconstruction by re-inforced Gore-Tex in esophageal submuscular tunneling: An experimental study.

    Science.gov (United States)

    Hodjati, Hossein; Baezzat, Saeed Reza; Fazelzadeh, Afsoon; Tanideh, Nader; Geramizadeh, Bita

    2011-01-01

    Tracheal reconstructions are aimed at rearranging or replacing parts of the tracheal tissue by different techniques. Here we introduce a new technique for tracheal reconstruction. In 10 adult dogs, after intubation with an endotracheal tube, a segment of trachea including seven tracheal rings was resected circumferentially. A submuscular tunnel was induced between mucosal and muscular layers of the adjacent esophagus lying right next to the trachea. The esophageal submuscular tunnel starts and ends exactly at the level of distal and proximal ends of tracheal resection, respectively. Inforced Gore-Tex passed through the esophageal submuscular tunnel the distal segment of trachea and end-to-end anastomosis were made between distal ends of Gore-Tex and trachea, then endotracheal tube removed and the same procedure was made for proximal ends of Gore-Tex and trachea. Afterward, the proximal and distal ends of the esophageal tunnel were approximated to proximal and distal tracheal parts over the anastomosis. All dogs, except one due to anesthetic problem, survived and tolerated the operation; the first two dogs experienced postoperative fever, aspiration pneumonia, and died due to tracheoesophageal fistula. All survived animals were eating and barking well. We started to scarify dogs at least 6 and 12 weeks after operation for microscopy and pathologic examination. The Gore-Texes were patent and supported externally with fibrous connective tissue in esophageal tunneling, with in growth of respiratory epithelium on inner surfaces. Air tightness, good re-epithelialization, and relatively no limitation of esophageal length and no risk of luminal collapse are advantages of tracheal reconstruction by submuscular esophageal tunneling. This new method is worthy of further investigation, as it is technically feasible and easy to implement.

  19. Stability of Large Parallel Tunnels Excavated in Weak Rocks: A Case Study

    Science.gov (United States)

    Ding, Xiuli; Weng, Yonghong; Zhang, Yuting; Xu, Tangjin; Wang, Tuanle; Rao, Zhiwen; Qi, Zufang

    2017-09-01

    Diversion tunnels are important structures for hydropower projects but are always placed in locations with less favorable geological conditions than those in which other structures are placed. Because diversion tunnels are usually large and closely spaced, the rock pillar between adjacent tunnels in weak rocks is affected on both sides, and conventional support measures may not be adequate to achieve the required stability. Thus, appropriate reinforcement support measures are needed, and the design philosophy regarding large parallel tunnels in weak rocks should be updated. This paper reports a recent case in which two large parallel diversion tunnels are excavated. The rock masses are thin- to ultra-thin-layered strata coated with phyllitic films, which significantly decrease the soundness and strength of the strata and weaken the rocks. The behaviors of the surrounding rock masses under original (and conventional) support measures are detailed in terms of rock mass deformation, anchor bolt stress, and the extent of the excavation disturbed zone (EDZ), as obtained from safety monitoring and field testing. In situ observed phenomena and their interpretation are also included. The sidewall deformations exhibit significant time-dependent characteristics, and large magnitudes are recorded. The stresses in the anchor bolts are small, but the extents of the EDZs are large. The stability condition under the original support measures is evaluated as poor. To enhance rock mass stability, attempts are made to reinforce support design and improve safety monitoring programs. The main feature of these attempts is the use of prestressed cables that run through the rock pillar between the parallel tunnels. The efficacy of reinforcement support measures is verified by further safety monitoring data and field test results. Numerical analysis is constantly performed during the construction process to provide a useful reference for decision making. The calculated deformations are in

  20. A comparative study on microscopic agglutination test and counterimmunoelectrop- horesis for early detection of human leptospirosis

    Directory of Open Access Journals (Sweden)

    R Saravanan

    2014-01-01

    Full Text Available Background and Objectives: Leptospirosis is a potentially fatal bacterial disease that mimics many diseases; therefore, laboratory confirmation is pivotal. Though microscopic agglutination test (MAT is accepted as World Health Organisation (WHO reference test, it has got many pitfalls such as being hazardous, tedious, cumbersome and expensive. Counterimmunoelectrophoresis (CIE is popularly used for diagnosing many infectious diseases but rarely for Leptospirosis. The aim of this study is to find suitability of CIE for the routine laboratory diagnostic purposes. Materials and Methods: Repeat sampling (paired sera was possible from 401 subjects of which 181 were in-patients of Salem Government General and Private Hospitals and the remaining 220 MAT negative healthy College students gave their consent for the study. All the 802 sera samples were collected from January 2009 to November 2012 and subjected to the present study. After carrying out MAT and CIE on the suspected and control samples, a comparative evaluation was conducted. McNemars test method was used to find out the significant difference between the two tests in the early diagnosis. Result: The sensitivity, specificity, Positive Predictive value (PPV, Negative Predictive value (NPV and Efficiency test for CIE were 96.80%, 89.28%, 95.23%, 92.59% and 94.47%, respectively. The corresponding values for MAT were 95.90%, 89.83%, 95.08%, 91.37% and 93.92%, respectively. There was no significant difference between MAT and CIE at 95% and 99% confidence intervals according to McNemars test. P value in the early stage of illness was greater for CIE than MAT when Polymerase Chain Reaction (PCR was used as Gold Standard of diagnosis. Interpretation and conclusion: It was concluded that the CIE could be advantageous over MAT due to its safety, rapidity, simplicity, economic and easy for large number of samples. It can answer little earlier than MAT and found as reliable as that of MAT. Since both the

  1. A compact light-sheet microscope for the study of the mammalian central nervous system.

    Science.gov (United States)

    Yang, Zhengyi; Haslehurst, Peter; Scott, Suzanne; Emptage, Nigel; Dholakia, Kishan

    2016-05-24

    Investigation of the transient processes integral to neuronal function demands rapid and high-resolution imaging techniques over a large field of view, which cannot be achieved with conventional scanning microscopes. Here we describe a compact light sheet fluorescence microscope, featuring a 45° inverted geometry and an integrated photolysis laser, that is optimized for applications in neuroscience, in particular fast imaging of sub-neuronal structures in mammalian brain slices. We demonstrate the utility of this design for three-dimensional morphological reconstruction, activation of a single synapse with localized photolysis, and fast imaging of neuronal Ca(2+) signalling across a large field of view. The developed system opens up a host of novel applications for the neuroscience community.

  2. Electron microscope study of thallium-induced alterations in the oligodendrocytes of the rat area postrema.

    Science.gov (United States)

    Hasan, M; Bajpai, V K; Shipstone, A C

    1977-01-01

    Thallotoxicosis following accidental ingestion of thallium in rodenticides and in cases of homicidal and suicidal ingestion are well documented in the literature. The mechanism of action of thallium, in particular the pathogenesis of its neurotoxic manifestations, is not entirely clear. This is the first electron microscopic investigation dealing with the effect of thallium on the oligodendrocytes of the area postrema. The area postrema is devoid of a blood-brain barrier, indicating that the hemoneural transport of thallous ions may be quite substantial in this region. Rats weighing 155-175 g were given intraperitoneal injections of 5 mg/kg thallous acetate for 7 days (35 mg/kg total dose). Following perfusion-fixation, ultrathin sections of area postrema were examined with an electron microscope. The oligodendrocytes exhibited pleomorphic vacuolated dense bodies in their perikaryon. The findings were also suggestive of the fact that either the multiplication of oligodendrocytes or their aggregation to form "giant cell" was operative.

  3. Transmission electron microscope studies of the chromium cast iron modified at use of B4C addition

    Directory of Open Access Journals (Sweden)

    K. Labisz

    2010-10-01

    Full Text Available Results of studies of the high alloy chromium cast iron with boron addition in form of the B4C phase powder are presented in this paper.The main field of interest is the identification of phases based on the transmission electron microscope study, occurred in this alloy aftersolidification process. The structure mainly consists of the austenite matrix and M7C3 carbide identified as the Cr7C3 phase.

  4. Microscopical study of K isomers in the nuclear region A ∼ 180

    International Nuclear Information System (INIS)

    Libert, J.; Quentin, P.; Pillet, N.; Ponsa, A.

    1997-01-01

    At present the K isomers are the best candidates for high density energy storage, although one of the major problems resides in the availability of simple and fast storage mechanisms. To respond to this question it is necessary to know thoroughly the structure of the concerned isomers and low energy modes of excitation. Particularly, proper to this type of studies is the region of A ∼ 180, where a large number of K isomers are known at present ( 178 Hf, 179 Hf and 180 Ta). Microscopic calculations using Skyrme SIII plus a simple pairing interaction lead to a good reproduction of certain single particle and collective spectroscopic properties of 178 Hf. In this region the spectroscopic properties are governed by three single proton states (5/2 - , 7/2 - and 9/2 + ) and by two single neutron states (7/2 + , 9/2 - ). The computed quasi-particle spectrum reproduces within 100 keV the energies of the isomeric states 16 + , 14 - , 25/2 - and 9 - . Based on this agreement one can predict a band spectroscopy rich in high K values due to a plenty of possible single particle combinations which have themselves high K value. Particularly, one have to stress the quasi-degeneracy of a K π = 15 + with the 16 + configuration in 178 Hf. Should this prediction experimentally be confirmed interesting consequences have to be expected on the spectroscopy above the 16 + isomer of 178 Hf as well as on the states implied in the decay of this storage state. Actually, 1 MeV above the 16 + state one can note isolated states reachable by parity breaking (or not breaking) transitions which could be mixture of K = 15, 14, 13, etc structures due to Coriolis interaction. The calculation reported are although simple (the approximation of the free quasi-particles on the BCS vacuum of 178 Hf). Under current study are the quantitative consequences of the Coriolis coupling, the decrease of pairing gaps with increasing quasi-particle number, the Hartree-Fock polarization (even and odd under time

  5. Results of design studies and wind tunnel tests of an advanced high lift system for an Energy Efficient Transport

    Science.gov (United States)

    Oliver, W. R.

    1980-01-01

    The development of an advanced technology high lift system for an energy efficient transport incorporating a high aspect ratio supercritical wing is described. This development is based on the results of trade studies to select the high lift system, analysis techniques utilized to design the high lift system, and results of a wind tunnel test program. The program included the first experimental low speed, high Reynolds number wind tunnel test for this class of aircraft. The experimental results include the effects on low speed aerodynamic characteristics of various leading and trailing edge devices, nacelles and pylons, aileron, spoilers, and Mach and Reynolds numbers. Results are discussed and compared with the experimental data and the various aerodynamic characteristics are estimated.

  6. Comparative study of different microscopic techniques and culture media for the isolation of dermatophytes

    Directory of Open Access Journals (Sweden)

    Singh S

    2003-01-01

    Full Text Available PURPOSE: To evaluate the usefulness of two different microscopic techniques and three different culture media for the identification and isolation of dermatophytes from clinical samples. METHODS: Skin, hair and nail samples from 260 clinically suspected cases of dermatophytosis were screened by direct microscopic examination using 10% potassium hydroxide (KOH with and without 40% dimethyl sulphoxide (DMSO mounts. All the samples were inoculated for culture in Sabouraud dextrose agar (SDA, dermatophyte test medium (DTM and ready to use enriched dermatophyte medium (EDM. RESULTS: Fungal elements were detected in 157 samples by both the methods but faster and better visualization was noted with 40% DMSO added to 10% KOH. Fungi were recovered from SDA, DTM and EDM in 96.5%, 98.3% and 85.3% of the cases respectively. CONCLUSIONS: When performing direct microscopic examination of skin, hair and nail for dermatophytes, addition of 40% DMSO to the KOH mount gives better and faster results. The efficiency of SDA and DTM was found almost equal and slightly better than EDM. The EDM, although quite efficient with 85.3% isolation rate, requires further evaluation as its ready to use format makes the application and microscopy much easier and faster.

  7. Tunneling through a time-dependent barrier – a numerical study

    Indian Academy of Sciences (India)

    involved in what may be simply the stretching of a chemical bond to destruction. Or, as much to the point, an insulating layer separating two semiconducting layers may be sub- ject to a bias that effects the ease with which electrons can tunnel through it. Except, in the highly rarefied atmosphere prevailing in supersonic jets ...

  8. Surface x-ray scattering and scanning tunneling microscopy studies at the Au(111) electrode

    International Nuclear Information System (INIS)

    Ocko, B.M.; Magnussen, O.M.; Wang, J.X.; Adzic, R.R.

    1993-01-01

    This chapter reviews Surface X-ray Scattering and Scanning Tunneling Microscopy results carried out at the Au(111) surface under electrochemical conditions. Results are presented for the reconstructed surface, and for bromide and thallium monolayers. These examples are used to illustrate the complementary nature of the techniques

  9. Wind Tunnel Measurement of Turbulent and Advective Scalar Fluxes: A Case Study on Intersection Ventilation

    Czech Academy of Sciences Publication Activity Database

    Kukačka, Libor; Nosek, Štěpán; Kellnerová, Radka; Jurčáková, Klára; Jaňour, Zbyněk

    2012-01-01

    Roč. 2012, č. 381357 (2012), s. 1-13 ISSN 1537-744X Institutional research plan: CEZ:AV0Z20760514 Keywords : air pollution * atmospheric boundary layer * wind tunnel modelling * contaminant spreading * street canyon Subject RIV: DG - Athmosphere Sciences, Meteorology Impact factor: 1.730, year: 2012 http://www.tswj.com/2012/381357/

  10. Scanning tunneling microscopy studies of thin foil x-ray mirrors

    DEFF Research Database (Denmark)

    Christensen, Finn Erland; Besenbacher, Flemming; Garnaes, Jorgen

    1990-01-01

    In this paper scanning tunneling microscopy (STM) measurements of x-ray mirrors are presented. The x-ray mirrors are 0.3 mm thick dip-lacquered aluminum foils coated with gold by evaporation, as well as state-of-the-art polished surfaces coated with gold, platinum, or iridium. The measurements...

  11. Feasibility study and technical proposal for seismic monitoring of tunnel boring machine in Olkiluoto

    International Nuclear Information System (INIS)

    Saari, J.; Lakio, A.

    2009-01-01

    In Olkiluoto, Posiva Oy has operated a local seismic network since February 2002. The purpose of the microearthquake measurements at Olkiluoto is to improve understanding of the structure, behaviour and long term stability of the bedrock. The studies include both tectonic and excavation-induced microearthquakes. An additional task of monitoring is related to safeguarding of the ONKALO. The possibility to excavate an illegal access to the ONKALO, have been concerned when the safeguards are discussed. Therefore all recorded explosions in the Olkiluoto area and in the ONKALO are located. If a concentration of explosions is observed, the origin of that is found out. Also a concept of hidden illegal explosions, detonated at the same time as the real excavation blasts, has been examined. According to the experience gained in Olkiluoto, it can be concluded that, as long the seismic network is in operation and the results are analysed by a skilled person, it is practically impossible to do illegal excavation by blasts. In this report a possibility of seismic monitoring of illegal excavation done by tunnel boring machine (TBM) has been investigated. Characteristics of the seismic signal generated by the raise boring machine are described. According to this study, it can be concluded that the generated seismic signal can be detected and the source of the signal can be located. However, this task calls for different kind of monitoring system than that, which is currently used for monitoring microearthquakes and explosions. The presented technical proposal for seismic monitoring of TBM in Olkiluoto is capable to detect and locate TBM coming outside the ONKALO area about two months before it would reach the ONKALO. (orig.)

  12. Three dimensional transient electromagnetic model study for fracture prediction from tunnel face; Sanjigen model keisan ni yoru TEM ho no tunnel zenpo tansa eno tekiyosei no kento

    Energy Technology Data Exchange (ETDEWEB)

    Wada, K.; Tsutsui, T.; Saito, A. [Mitsui Mineral Development Engineering Co. Ltd., Tokyo (Japan); Hara, T. [Toda Corp., Tokyo, (Japan); Zhdanov, M. [University of Utah, UT (United States)

    1996-10-01

    In order to apply TEM model to fracture prediction at tunnel face, 3-D TEM model computation by FEM was conducted by installing a transmission loop on a tunnel face. MT field responses diffusing into the 3-D model were computed by time-domain difference calculus, and analytical precision was improved by introducing a staggered grid method. In the case where a low resistive zone exists before a tunnel face, time variance in diffused eddy current and induction current in the low resistive zone could be obtained. The difference in tunnel-axial transient curve (transient phenomenon curve in magnetic field) between uniform medium and low resistive zone models was based on the absorption process of diffused eddy current into the low resistive zone, and the expanding process of it toward the outside. Change in background condition could be predicted from the background and the ratio of transient curves every measurement. The detection limit of the low resistive zone was dependent on resistivity contrast, distance and geometry. Fluctuation in measurement due to noises and S/N ratio were also essential. 3 refs., 10 figs.

  13. A spectroscopic and microscopic study of uranium speciation in the infiltration pond sediments at Hanford, USA

    International Nuclear Information System (INIS)

    Wang, Z.; Zachara, J.M.; McKinley, J.P.; Smith, S.C.; Qafoku, O.; Catalano, J.G.

    2005-01-01

    Full text of publication follows: The infiltration ponds in the '300 area' of the U.S. Department of Energy Hanford Site received large volumes of nuclear waste that contained tens of metric tons of uranium along with high concentrations of other metals such as Cu, Fe, Mn, Al and Ca during their operations from 1943 to 1975. Leaching and migration of uranium in the pond sediments threatens the integrity of the Columbia River that is with 100 m of these ponds. A clear understanding of the speciation of uranium in the pond sediments is key to predict the dissolution and migration behavior of uranium and to develop any necessary containment or decontamination strategies. In this work, we studied the speciation of uranium in a series of Hanford infiltration pond sediments and its changes after dissolution in various solution media including DDI water, sodium bicarbonate (pH 9.5) and 1 M sodium acetate (pH 4.8), using liquid-helium temperature time-resolved laser-induced fluorescence spectroscopy (TRLFS) and time-resolved laser-induced fluorescence imaging spectro-microscopy (TRLFISM), and X-ray absorption spectroscopy (XAS). XAS analysis indicated that uranium in the sediment primarily existed in the 6+ oxidation state. The TRLFS spectra of uranium in several sediments resembled those in natural, uranyl-bearing calcite and those reported for uranium co-precipitated synthetic calcite and aragonite, suggesting the presence of similar uranyl coordination environments. The TRLFS spectra varied with both sediment location and depth and there was not a linear correlation between the spectral intensity and the overall concentration of uranium, indicating the presence of multiple uranium species. While for some sediment the major spectral characteristics appeared to remain the same after extraction using DDI water, sodium bicarbonate and even sodium acetate, for others, spectral changes were observed. Comparison of the sediment uranium TRLFS spectra with a standard spectral

  14. Metropolitan transportation management center : a case study : Boston Central Artery/Tunnel Integrated Project control system : responding to incidents rapidly and effectively

    Science.gov (United States)

    1999-10-01

    The following case study provides a snapshot of the Boston Central Artery/Tunnel Integration Project Control System (IPCS) operations control center. It follows the outline provided in the companion document, Metropolitan Transportation Management Ce...

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

    Science.gov (United States)

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

    1995-04-01

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

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

    Directory of Open Access Journals (Sweden)

    K S Sridhara

    2014-01-01

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

  17. Co on Pt(111) studied by spin-polarized scanning tunneling microscopy and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Meier, F.K.

    2006-07-01

    In this thesis the electronic properties of the bare Pt(111) surface, the structural, electronic, and magnetic properties of monolayer and double-layer high Co nanostructures as well as the spin-averaged electronic structure of single Co atoms on Pt(111) were studied by low-temperature scanning tunneling microscopy (STM) and spectroscopy (STS). The experiments on the bare Pt(111) surface and on single Co atoms have been performed in an STM facility operating at temperatures of down to 0.3 K and at magnetic fields of up to 14 T under ultra-high vacuum conditions. The facility has been taken into operation within the time period of this thesis and its specifications were tested by STS measurements. These characterization measurements show a very high stability of the tunneling junction and an energy resolution of about 100 {mu}eV, which is close to the thermal limit. The investigation of the electronic structure of the bare Pt(111) surface reveals the existence of an unoccupied surface state. By a comparison of the measured dispersion to first-principles electronic structure calculations the state is assigned to an sp-derived surface band at the lower boundary of the projected bulk band gap. The surface state exhibits a strong spin-orbit coupling induced spin splitting. The close vicinity to the bulk bands leads to a strong linear contribution to the dispersion and thus to a deviant appearance in the density of states in comparison to the surface states of the (111) surfaces of noble metals. A detailed study of Co monolayer and double-layer nanostructures on the Pt(111) surface shows that both kinds of nanostructures exhibit a highly inhomogeneous electronic structure which changes at the scale of only a few Aa due to a strong stacking dependence with respect to the Pt(111) substrate. With the help of first principles calculations the different spectroscopic appearance for Co atoms within the Co monolayer is assigned to a stacking dependent hybridization of Co states

  18. The Scanning TMR Microscope for Biosensor Applications

    Directory of Open Access Journals (Sweden)

    Kunal N. Vyas

    2015-04-01

    Full Text Available We present a novel tunnel magnetoresistance (TMR scanning microscopeset-up capable of quantitatively imaging the magnetic stray field patterns of micron-sizedelements in 3D. By incorporating an Anderson loop measurement circuit for impedancematching, we are able to detect magnetoresistance changes of as little as 0.006%/Oe. By 3Drastering a mounted TMR sensor over our magnetic barcodes, we are able to characterisethe complex domain structures by displaying the real component, the amplitude and thephase of the sensor’s impedance. The modular design, incorporating a TMR sensor withan optical microscope, renders this set-up a versatile platform for studying and imagingimmobilised magnetic carriers and barcodes currently employed in biosensor platforms,magnetotactic bacteria and other complex magnetic domain structures of micron-sizedentities. The quantitative nature of the instrument and its ability to produce vector maps ofmagnetic stray fields has the potential to provide significant advantages over other commonlyused scanning magnetometry techniques.

  19. Experimental study on tunnel lining joints temporarily strengthened by SMA bolts

    International Nuclear Information System (INIS)

    Wu, Bo; Ou, Yunlong

    2014-01-01

    Shield tunnels have been widely used in city metros all over the world. During the long-term period of the metro operation, the joints of shield tunnel’s neighboring segments may degrade due to some environmental factors, leading to the increasing of the joint opening and some resulting adverse consequences. In this paper, a temporary strengthening method by using shape memory alloy (SMA) bolts is proposed and experimentally studied for the joints of neighboring segments, and a revised electric heating method which suits with the strengthening method is presented and experimentally validated for the SMA bolts. The purpose of the proposed temporary strengthening method is to create favorable conditions for the following permanent strengthening. Test results show that: (a) for the joints of shield tunnel’s neighboring segments, the strengthening method can effectively reduce the joint opening, joint deflection, concrete strain in joint’s compression zone, and strain of joint’s steel bolts; (b) the revised electric heating method can be used to heat the SMA rod to a temperature higher than the SMA’s austenite finish temperature quickly, and the average heating rate related to Type 2 inner resistance element is larger than that related to Type 1 inner resistance element; and (c) the reduction percentages of the joint opening increment, joint deflection, concrete strain in joint’s compression zone, and strain of joint’s steel bolts for Specimen I are all larger than those for Specimen II, implying that the less the joint opening is, the more significant the strengthening effect is. (paper)

  20. A wind tunnel study on the effect of trees on PM2.5 distribution around buildings.

    Science.gov (United States)

    Ji, Wenjing; Zhao, Bin

    2018-03-15

    Vegetation, especially trees, is effective in reducing the concentration of particulate matter. Trees can efficiently capture particles, improve urban air quality, and may further decrease the introduction of outdoor particles to indoor air. The objective of this study is to investigate the effects of trees on particle distribution and removal around buildings using wind tunnel experiments. The wind tunnel is 18m long, 12m wide, and 3.5m high. Trees were modeled using real cypress branches to mimic trees planted around buildings. At the inlet of the wind tunnel, a "line source" of particles was released, simulating air laden with particulate matter. Experiments with the cypress tree and tree-free models were conducted to compare particle concentrations around the buildings. The results indicate that cypress trees clearly reduce PM 2.5 concentrations compared with the tree-free model. The cypress trees enhanced the PM 2.5 removal rate by about 20%. The effects of trees on PM 2.5 removal and distribution vary at different heights. At the base of the trees, their effect on reducing PM 2.5 concentrations is the most significant. At a great height above the treetops, the effect is almost negligible. Copyright © 2017 Elsevier B.V. All rights reserved.

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

    Science.gov (United States)

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

    1974-01-01

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

  2. Scanning electron microscopic (Sem studies on fourth instar larva and pupa of Anopheles (Cellia stephensi Liston (Anophelinae: Culicidae

    Directory of Open Access Journals (Sweden)

    Jagbir Singh Kirti

    2014-12-01

    Full Text Available Anopheles (Cellia stephensi Liston is a major vector species of malaria in Indian subcontinent. Taxonomists have worked on its various morphological aspects and immature stages to explore additional and new taxonomic attributes. Scanning electron microscopic (SEM studies have been conducted on the fourth instar larva and pupa of An. stephensi to find additional taxonomic features for the first time from Punjab state.

  3. [Quality assessment of microscopic examination in tuberculosis diagnostic laboratories: a preliminary study].

    Science.gov (United States)

    Simşek, Hülya; Ceyhan, Ismail; Tarhan, Gülnur; Güner, Uğur

    2010-10-01

    Recently, the diagnosis of pulmonary tuberculosis (TB) has based on smear microscopy in the Direct Observed Treatment Strategy (DOTS) programme which provides the basis of treatment worldwide. Microscopic detection of AFB (Acid-Fast Bacilli) is one of the main components in the National TB Control Programmes (NTCP). Precision level in microscopy procedures and evaluations are the most important steps for accurate diagnosis of the disease and to initiate proper treatment. Therefore, the external quality assessment (EQA) is the most important implement to provide the reliability and validity of tests. In countries where NTCP are performed, this task is fulfilled by the National Reference Laboratories (NRL) according to the guidelines of the World Health Organization (WHO). For this purpose a pilot study was initiated by the central NRL of Turkey for EQA of AFB smear microscopy as part of the NTCP on January 1, 2005. A total of 5 laboratories of which 2 were district TB laboratories (A, B), 2 were tuberculosis control dispensaries (C, D), 1 was a national reference laboratory (E), participated in this study. Blind re-checking method (re-examination of randomly selected slides) was used for the evaluation, and the slides were sent to the central NRL with 3 months interval, four times a year, selected according to LQAS (Lot Quality Assurance Sampling) guides. In the re-evaluation of the slides, false positivity (FP), false negativity (FN) and quantification errors (QE) were noted. Laboratory A, sent totally 525 slides between January 1, 2005 and April 1, 2008. In the result of re-checking, 514 (97.9%) slides were found concordant, and 11 (2.1%) were discordant (10 FP, 1 FN). Laboratory B, participated in the study between October 1, 2005 and July 1, 2006 and of the 67 re-examined slides, 60 (89.5%) were concordant and 7 (10.5%) were discordant (2 FP, 0 FN, 5 QE). Laboratory C, sent 235 slides between January 1, 2005 and April 1, 2006; of them 218 (92.8%) were detected

  4. Microscope-Integrated OCT Feasibility and Utility With the EnFocus System in the DISCOVER Study.

    Science.gov (United States)

    Runkle, Anne; Srivastava, Sunil K; Ehlers, Justis P

    2017-03-01

    To evaluate the feasibility and utility of a novel microscope-integrated intraoperative optical coherence tomography (OCT) system. The DISCOVER study is an investigational device study evaluating microscope-integrated intraoperative OCT systems for ophthalmic surgery. This report focuses on subjects imaged with the EnFocus prototype system (Leica Microsystems/Bioptigen, Morrisville, NC). OCT was performed at surgeon-directed milestones. Surgeons completed a questionnaire after each case to evaluate the impact of OCT on intraoperative management. Fifty eyes underwent imaging with the EnFocus system. Successful imaging was obtained in 46 of 50 eyes (92%). In eight cases (16%), surgical management was changed based on intraoperative OCT findings. In membrane peeling procedures, intraoperative OCT findings were discordant from the surgeon's initial impression in seven of 20 cases (35%). This study demonstrates the feasibility of microscope-integrated intraoperative OCT using the Bioptigen EnFocus system. Intraoperative OCT may provide surgeons with additional information that may influence surgical decision-making. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:216-222.]. Copyright 2017, SLACK Incorporated.

  5. Microscopic coupled-channels study of scattering and breakup of light heavy-ions

    International Nuclear Information System (INIS)

    Sakuragi, Yukinori; Yahiro, Masanobu; Kamimura, Masayasu.

    1987-01-01

    The elastic and inelastic scattering and the breakup reactions of light heavy-ions, particularly 6 Li, 7 Li and 12 C, are investigated on the basis of a microscopic coupled-channels method. The bound states and resonant and non-resonant continuum states of the projectile nucleus are taken into account. The wave functions of those states are given by a microscopic cluster model assuming α-d, α-t and 3α for the three projectile nuclei, respectively. The unbound continuum states are approximately treated with the method of coupled discretized continuum channels (CDCC). The real parts of all the diagonal and coupling potentials are given by doubly folding the M3Y effective nucleon-nucleon interaction into the nucleon transition densities of the projectile nucleus and the ground-state density of the target nucleus. The microscopic CDCC method is successfully applied to the analyses of the scattering and the breakup of 6,7 Li and 12 C in a wide range of the target mass and the bombarding energy. The effect of the projectile virtual breakup on the elastic scattering is strikingly large and absolutely important to reproduce the observed cross sections. The dynamical polarization (DP) potentials induced by the breakup of the 6,7 Li and 12 C projectiles are found to be strongly repulsive and, for 6 Li, very weakly absorptive, which is quite different from what has been known for DP potentials induced by the excitation of usual collective states. Unified understanding is presented for various types of possible DP potentials due to weak-coupling channels through strong-coupling channels. Further discussions are made on the roles of the coupling between the breakup channels and that between the elastic channel and the breakup channels in the scattering and breakup reactions of the light heavy-ions. (author)

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

    Science.gov (United States)

    Brainard, W. A.; Salik, J.

    1980-01-01

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

  7. Studying aerosol light scattering based on aspect ratio distribution observed by fluorescence microscope.

    Science.gov (United States)

    Li, Li; Zheng, Xu; Li, Zhengqiang; Li, Zhanhua; Dubovik, Oleg; Chen, Xingfeng; Wendisch, Manfred

    2017-08-07

    Particle shape is crucial to the properties of light scattered by atmospheric aerosol particles. A method of fluorescence microscopy direct observation was introduced to determine the aspect ratio distribution of aerosol particles. The result is comparable with that of the electron microscopic analysis. The measured aspect ratio distribution has been successfully applied in modeling light scattering and further in simulation of polarization measurements of the sun/sky radiometer. These efforts are expected to improve shape retrieval from skylight polarization by using directly measured aspect ratio distribution.

  8. Atomic force microscopic study of folate receptors in live cells with functionalized tips

    Science.gov (United States)

    Girish, C. M.; Binulal, N. S.; Anitha, V. C.; Nair, Shantikumar; Mony, U.; Prasanth, R.

    2009-11-01

    Membrane associated folate receptors (FR) is gaining importance in cancer research. Understanding the FR density, distribution, and the strength of its interaction with ligands is crucial in cancer diagnostics and therapeutics. Here we reported the enhanced phase contrast image of FR by scanning with properly functionalized atomic force microscope (AFM) tips over live cell lines. The choice of the ligand was made for better interaction of tip with FR, expressed in the cell lines. The selectively enhanced force of interaction at the receptor molecule produced a considerable enhancement in the phase contrast between a receptor site and a nonreceptor site.

  9. Morphological studies of human sperm using the Aarhus X-ray microscope

    Science.gov (United States)

    Abraham-Peskir, Joanna V.; Chantler, Eric; Guttmann, Peter; Hjort, Tage; Medenwaldt, Robin; McCann, Christine; Uggerhøj, Erik; Vorup-Jensen, Thomas

    2000-05-01

    Using the Aarhus transmission X-ray microscope we have shown that the mitochondria of human spermatozoa can exist in two morphologically distinct states. We have also discovered new structures on the human spermatozoon surface. These structures manifest as clear vesicular bodies associated with specific membrane domains. They can occur around the acrosomal segment, the mid-piece region or at the basal region. Prior to our findings they were not described in the literature, even though they were clearly visible by light microscopy and ubiquitous among populations of sperm from fertile donors. We report on our findings and subsequent endeavours to elucidate the function of these fascinating structures.

  10. A three-dimensional X-ray diffraction microscope for deformation studies of polycrystals

    DEFF Research Database (Denmark)

    Fæster Nielsen, Søren; Lauridsen, E.M.; Juul Jensen, D.

    2001-01-01

    -dimensional X-ray diffraction (3DXRD) microscope installed at the European Synchrotron Radiation Facility in Grenoble provides a fast and non-destructive technique for mapping the embedded grains within thick samples in three dimensions. All essential features like the position, volume, orientation, stress......-state of the grains can be determined, including the morphology of the grain boundaries. The accuracy of this novel tracking technique is compared with electron microscopy (EBSP), and its 3-D capacity is demonstrated. (C) 2001 Elsevier Science B.V. All rights reserved....

  11. Spin tunnelling in mesoscopic systems

    Indian Academy of Sciences (India)

    We study spin tunnelling in molecular magnets as an instance of a mesoscopic phenomenon, with special emphasis on the molecule Fe8. We show that the tunnel splitting between various pairs of Zeeman levels in this molecule oscillates as a function of applied magnetic field, vanishing completely at special points in the ...

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

    Science.gov (United States)

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

    2009-02-01

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

  13. Utilizing Neon Ion Microscope for GaSb nanopatterning studies: Nanostructure formation and comparison with low energy nanopatterning

    Energy Technology Data Exchange (ETDEWEB)

    El-Atwani, Osman, E-mail: oelatwan25@gmail.com [School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Huynh, Chuong [Carl Zeiss Microscopy, LLC, One Corporation Way, Peabody, MA 01960 (United States); Norris, Scott [Department of Mathematics, Southern Methodist University, Dallas, TX 75275 (United States)

    2016-05-01

    Graphical abstract: - Highlights: • Carl Zeiss-neon ion microscope was used to irradiated GaSb surfaces with 5 keV neon. • In-situ imaging using helium beam and ex-situ imaging using an electron beam were performed. • Differences in imaging output between the helium and the electron beam were observed. • Transition occurred in the nanostructure type and formation mechanism as the energy is changed from 2 to 5 keV. • Collision cascade simulations suggested a transition toward bulk-driven mechanisms. - Abstract: Low energy irradiation of GaSb surfaces has been shown to lead to nanopillar formation. Being performed ex-situ, controlling the parameters of the ion beam for controlled nanopattern formation is challenging. While mainly utilized for imaging and cutting purposes, the development of multibeam (helium/neon) ion microscopes has opened the path towards the use of these microscopes for in-situ ion irradiation and nanopatterning studies. In this study, in-situ irradiation (neon ions)/imaging (helium ions) of GaSb surfaces is performed using Carl Zeiss-neon ion microscope at low energies (5 and 10 keV). Imaging with helium ions, nanodots were shown to form at particular fluences after which are smoothed. Ex-situ imaging with SEM showed nanopore formation of size controlled by the ion energy and fluence. Compared to lower energy ex-situ neon ion irradiation at similar fluxes, where nanopillars are formed, the results demonstrated a transition in the nanostructure type and formation mechanism as the energy is changed from 2 to 5 keV. Simulations show an increase in the ballistic diffusion and a decrease in the strength of phase separation as a function of ion energy in agreement with the suppression of nanopillar formation at higher energies. Collision cascade simulations suggest a transition toward bulk-driven mechanisms.

  14. Evolution of tunnelling causality and the 'Hartman-Fletcher effect'

    International Nuclear Information System (INIS)

    Olkhovsky, V.S.; Zaichenko, A.K.

    1995-01-01

    A new concept of the macroscopic tunneling time is added to our previous definition of the microscopic tunnelling time. The formally accusal jump of a time advance near the forward barrier wall is interpreted as a result of the superposition and interference of incoming and reflected waves. The reality 'H.-F. effect' is confirmed

  15. Performance studies of solar tunnel dryer for drying aonla (Embilica Officinalis) pulp

    International Nuclear Information System (INIS)

    Seveda, M. S.

    2012-01-01

    A solar tunnel dryer was constructed and evaluated the performance for drying aonla pulp. The dryer consists of a transparent UV stabilized plastic covered solar collector cum drying unit. Evaluation parameters are air temperature, solar insolation, moisture content, relative humidity and airflow rate. A minimum of 111.18 m 2 solar collector area is required to dry a batch 1000 kg aonla pulp in 16 hours (two days drying period). The initial and final moisture content considered were 424.93 and 10.08% dry basis, respectively. It was observed that on an average 43 per cent of higher temperature was obtained in solar tunnel dryer over the ambient temperature. The results obtained during the test period denoted that the maximum gained energy occurred at 13 o'clock hour and then gradually declined since the maximum solar radiation occurred at this time. (author)

  16. Molecular electronics of a single photosystem I reaction center: Studies with scanning tunneling microscopy and spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Lee, I.; Lee, J.W.; Warmack, R.J.; Allison, D.P.; Greenbaum, E. [Oak Ridge National Lab., TN (United States)

    1995-03-14

    Thylakoids and photosystem I (PSI) reaction centers were imaged by scanning tunneling microscopy. The thylakoids were isolated from spinach chloroplasts, and PSI reaction centers were extracted from thylakoid membranes. Because thylakoids are relatively thick nonconductors, they were sputter-coated with Pd/Au before imaging. PSI photosynthetic centers and chemically platinized PSI were investigated without sputter-coating. They were mounted on flat gold substrates that had been treated with mercaptoacetic acid to help bind the proteins. With tunneling spectroscopy, the PSI centers displayed a semiconductor-like response with a band gap of 1.8 eV. Lightly platinized (platinized for 1 hr) centers displayed diode-like conduction that resulted in dramatic contrast changes between images taken with opposite bias voltages. The electronic properties of this system were stable under long-term storage. 42 refs., 7 figs.

  17. Wind tunnel study of helical and straight-bladed vertical-axis wind turbine wakes

    Science.gov (United States)

    Bagheri, Maryam; Araya, Daniel

    2017-11-01

    It is hypothesized that blade curvature can serve as a passive means to control fluid entrainment and wake recovery in vertical-axis wind turbine (VAWT) arrays. We test this experimentally in a wind tunnel using two different VAWT configurations, one with straight blades and another with helical blades, keeping all other experimental parameters fixed. A small-scale, commercially available VAWT (15W max power) is used as the baseline wind tunnel model in each case. The commercial VAWT blades are replaced with either straight or helical blades that are 3D-printed extrusions of the same airfoil cross-section. Results from smoke flow visualization, three-component wake velocity measurements, and turbine power data are presented. These results give insight into the potential use of VAWTs with curved blades in utility-scale wind farms.

  18. Microgap Evaluation of Novel Hydrophilic and Hydrophobic Obturating System: A Scanning Electron Microscope Study.

    Science.gov (United States)

    Hegde, Vibha; Murkey, Laxmi Suresh

    2017-05-01

    The purpose of an endodontic obturation is to obtain a fluid tight hermetic seal of the entire root canal system. There has been an evolution of different materials and techniques to achieve this desired gap free fluid tight seal due to presence of anatomic complexity of the root canal system. To compare the microgap occurring in root canals obturated with hydrophilic versus hydrophobic systems using scanning electron microscope. Sixty extracted human single-rooted premolars were decoronated, instrumented using NiTi rotary instruments. The samples (n=20) were divided into three groups and obturated with Group A - (control group) gutta-percha with AH Plus, Group B - C-point with Smartpaste Bio and Group C - gutta-percha with guttaflow 2. The samples were split longitudinally into two halves and microgap was observed under scanning electron microscope in the apical 3 mm of the root canal. Group A (control) showed a mean difference of 8.54 as compared to 5.76 in group C. Group B showed the lowest mean difference of 0.83 suggesting that the hydrophilic system (C-point/Smartpaste Bio) produced least microgap as compared to the hydrophobic groups. Novel hydrophilic obturating system (C-points/ Smart-paste Bio) showed better seal and least microgap as compared to gutta-percha/guttaflow 2 and gutta-percha/ AH plus which showed gap at the sealer dentin interface due to less penetration and bonding of these hydrophobic obturating system.

  19. Microscopic dynamics of the hydrogen bonded systems studied by quasi-elastic slow neutron scattering

    International Nuclear Information System (INIS)

    Padureanu, I.; Aranghel, D.; Radulescu, A.; Ion, M.; Lechner, R. E.; Desmedt, A.; Pieper, J.

    2002-01-01

    The detailed understanding of the dynamical properties in highly viscous liquids such as glycerol, as well the supercooled and glassy state has attracted a great deal of attention. Glycerol is a hydrogen bonded forming system considered as intermediate between fragile and strong glasses with a glass transition temperature T g ∼ 185 K, melting temperature T m 290 K and a sound velocity V S ∼ 3330 m/s. Incoherent neutron scattering experiments from glasses generally show a broad feature with a maximum around 2 to 10 meV. This large contribution of such unusual low frequency excitations obeying the Bose-Einstein statistics to the density of states is referred to as 'boson peak' (BP) with a maximum near a frequency of 1 THz. A very much-debated question is the dramatic changes in the properties as well as the nature of the boson peak and the acoustic modes occurring in the neighborhood of this frequency. So far the experiments were not able to give a definite answer concerning the excitations giving rise to the boson peak. The inelastic X-ray scattering across the liquid glass transition in glycerol revealed propagating collective excitations in the whole liquid-glass transition temperature range. This conclusion challenges the present understanding of glasses and supercooled liquids particularly with their thermal properties. New experiments at lower temperatures than those investigated so far where the phonon scattering processes are less hard have been proposed. The relationship between the low frequency features, the microscopic structure, the nature of the forces and the atomic motions taking place at low frequencies is still an open question. According to the mode coupling theory (MCT) the glass transition is interpreted as a two-step process where the glass structure is softened by fast local motions (β - process) until some temperature T c >T g , where the structure breaks down leading to diffusion (α-process). It is an open question, whether MCT can

  20. Study of optical techniques for the Ames unitary wind tunnel: Digital image processing, part 6

    Science.gov (United States)

    Lee, George

    1993-01-01

    A survey of digital image processing techniques and processing systems for aerodynamic images has been conducted. These images covered many types of flows and were generated by many types of flow diagnostics. These include laser vapor screens, infrared cameras, laser holographic interferometry, Schlieren, and luminescent paints. Some general digital image processing systems, imaging networks, optical sensors, and image computing chips were briefly reviewed. Possible digital imaging network systems for the Ames Unitary Wind Tunnel were explored.

  1. New Technology and Experimental Study on Snow-Melting Heated Pavement System in Tunnel Portal

    OpenAIRE

    Lai, Jinxing; Qiu, Junling; Chen, Jianxun; Fan, Haobo; Wang, Ke

    2015-01-01

    In recent years, with the rapid growth of economy and sharp rise of motor vehicles in China, the pavement skid resistance in tunnel portals has become increasingly important in cold region. However, the deicing salt, snow removal with machine, and other antiskid measures adopted by highway maintenance division have many limitations. To improve the treatment effect, we proposed a new snow-melting approach employing electric heat tracing, in which heating cables are installed in the structural ...

  2. Scanning tunneling microscopy and spectroscopy studies of superconducting boron-doped diamond films

    Directory of Open Access Journals (Sweden)

    Terukazu Nishizaki, Yoshihiko Takano, Masanori Nagao, Tomohiro Takenouchi, Hiroshi Kawarada and Norio Kobayashi

    2006-01-01

    Full Text Available We report on scanning tunneling microscopy/spectroscopy (STM/STS experiments on (1 1 1-oriented epitaxial films of heavily boron-doped diamond grown by using the microwave plasma-assisted chemical vapor deposition method. STM/STS measurements were performed by 3He-refrigerator based STM under ultra-high vacuum. The STM topography on the film surface shows a corrugation (with a typical size of ~1 μm and grain-like microstructures (~5–20 nm. The tunneling conductance spectra do not show large spatial dependence and superconductivity is observed independent of the surface structures. The tunneling spectra are analyzed by the Dynes function and the superconducting energy gap is estimated to be Δ=0.87 meV at T=0.47 K, corresponding to 2Δ/kBTc=3.7. The relatively large value of the broadening parameter Γ=0.38 meV is discussed in terms of the inelastic electron scattering processes.

  3. Influence of Vehicle Speed on the Characteristics of Driver's Eye Movement at a Highway Tunnel Entrance during Day and Night Conditions: A Pilot Study.

    Science.gov (United States)

    Qin, Li; Dong, Li-Li; Xu, Wen-Hai; Zhang, Li-Dong; Leon, Arturo S

    2018-04-02

    The aim of this study was to investigate how vehicle speed influences the characteristics of driver's eye movement at highway tunnel entrances during day and night. In this study, six drivers' eye movement data (from 200 m before tunnel entrance to 200 m inside tunnel entrance) under five predetermined vehicle speeds (40, 50, 60, 70 and 80 km/h) in the daytime and three predetermined vehicle speeds (40, 60 and 80 km/h) in the nighttime were recorded using the non-intrusive Dikablis Professional eye-tracking system. Pupil size, the average fixation duration time and the average number of fixation were analyzed and then the influence of the vehicle speed on these parameters was evaluated by means of IBM SPSS Statistics 20.0. The results for pupil size in daytime increased when approaching the tunnel entrance, while as for nighttime, pupil size decreased when approaching the tunnel entrance and then increased after entering the tunnel. The pupil size in daytime has a significant negative correlation with vehicle speed, while the pupil size in nighttime did not show a significant association with vehicle speed. Furthermore, the average fixation duration in daytime increased when entering the tunnel, and had a significant negative correlation with vehicle speed. Also, the average number of fixations in daytime decreased when entering the tunnel and has a significant negative correlation with vehicle speed. However, the average fixation duration and the average number of fixations in nighttime did not show any significant association with vehicle speed. Moreover, limitations and future directions of the study are discussed for the further investigation.

  4. Intramolecular cyclization of diketopiperazine formation in solid-state enalapril maleate studied by thermal FT-IR microscopic system.

    Science.gov (United States)

    Lin, Shan-Yang; Wang, Shun-Li; Chen, Ting-Fang; Hu, Ting-Chou

    2002-09-01

    The pathway of diketopiperazine (DKP) formation of solid-state enalapril maleate has been studied by using a novel Fourier transform infrared microspectroscope equipped with a thermal analyzer (thermal FT-IR microscopic system). The thermogram of the conventional differential scanning calorimetry (DSC) method was also compared. The results show new evidence of IR peaks at 3250 cm(-1) (the broad O-H stretching mode of water), and at 1738 and 1672 cm(-1) (the carbonyl band of DKP), indicating DKP formation in enalapril maleate via intramolecular cyclization. Moreover, the disappearance of IR peaks from enalapril maleate at 3215 cm(-1) (the secondary amine), 1728 cm(-1) (the carbonyl group of carboxylic acid), and 1649 cm(-1) (the carbonyl stretching of tertiary amide) also confirmed the DKP formation. The thermal FT-IR microscopic system clearly evidenced that the DKP formation in enalapril maleate started from 129 degrees C, and reached a maximum at 137 degrees C. This result was also confirmed by the conventional DSC thermogram of the compressed mixture of KBr powder and enalapril maleate, in which an endothermic peak at 144 degrees C with an extrapolated onset temperature at 137 degrees C was observed. This strongly suggests that the thermal FT-IR microscopic system was able to qualitatively detect the formation of DKP derivatives in solid-state enalapril maleate via intramolecular cyclization.

  5. LEP tunnel monorail

    CERN Multimedia

    1985-01-01

    A monorail from CERN's Large Electron Positron collider (LEP, for short). It ran around the 27km tunnel, transporting equipment and personnel. With its 27-kilometre circumference, LEP was the largest electron-positron accelerator ever built and ran from 1989 to 2000. During 11 years of research, LEP's experiments provided a detailed study of the electroweak interaction. Measurements performed at LEP also proved that there are three – and only three – generations of particles of matter. LEP was closed down on 2 November 2000 to make way for the construction of the Large Hadron Collider in the same tunnel.

  6. Case study of geostructural prospect of a tunnel by using geophysical methods; Butsuri tansa ni yoru tunnel chisan yosoku to jissai

    Energy Technology Data Exchange (ETDEWEB)

    Ueda, H. [Japan Railway Construction Public Corp., Tokyo (Japan); Kawakami, J. [Taisei Construction Corp., Tokyo (Japan); Nagasue, I.; Hiwatashi, S.; Wakuno, M. [Oyo Corp., Tokyo (Japan)

    1997-05-27

    A preliminary survey was carried out by combining elastic wave exploration (using a refraction method) and electrical exploration (using a resistivity imaging method) on a long tunnel planned in a granite distributed area. This paper describes a case of verifying geological condition in the area by using a trial survey well and horizontal boring. This tunnel goes through the Seburi mountainous area on the border of Fukuoka Prefecture and Saga Prefecture for a total distance of 12 km. The refraction method and the resistivity imaging method were selected from the necessity of identifying the weathering condition in natural ground, and distributions of fault crush zones and underground water in a section extending 560 m from the well entrance. As a result of comparing the natural ground condition interpreted from the geophysical survey results with the construction records, the fault was detected as a cracked or deformed section in the part where the resistivity value changes abruptly or where the resistivity is low. The tunnel natural ground classification showed a good correspondence with the elastic wave velocities. The largest flooding section showed a good agreement with the section where the resistivity changes suddenly to a lateral direction. Thus, the geological information interpreted from both surveys presented a good correspondence with the construction records, leading to a judgment that the prediction is possible. 3 refs., 4 figs., 5 tabs.

  7. Eye Movement Training and Suggested Gaze Strategies in Tunnel Vision - A Randomized and Controlled Pilot Study.

    Directory of Open Access Journals (Sweden)

    Iliya V Ivanov

    Full Text Available Degenerative retinal diseases, especially retinitis pigmentosa (RP, lead to severe peripheral visual field loss (tunnel vision, which impairs mobility. The lack of peripheral information leads to fewer horizontal eye movements and, thus, diminished scanning in RP patients in a natural environment walking task. This randomized controlled study aimed to improve mobility and the dynamic visual field by applying a compensatory Exploratory Saccadic Training (EST.Oculomotor responses during walking and avoiding obstacles in a controlled environment were studied before and after saccade or reading training in 25 RP patients. Eye movements were recorded using a mobile infrared eye tracker (Tobii glasses that measured a range of spatial and temporal variables. Patients were randomly assigned to two training conditions: Saccade (experimental and reading (control training. All subjects who first performed reading training underwent experimental training later (waiting list control group. To assess the effect of training on subjects, we measured performance in the training task and the following outcome variables related to daily life: Response Time (RT during exploratory saccade training, Percent Preferred Walking Speed (PPWS, the number of collisions with obstacles, eye position variability, fixation duration, and the total number of fixations including the ones in the subjects' blind area of the visual field.In the saccade training group, RTs on average decreased, while the PPWS significantly increased. The improvement persisted, as tested 6 weeks after the end of the training. On average, the eye movement range of RP patients before and after training was similar to that of healthy observers. In both, the experimental and reading training groups, we found many fixations outside the subjects' seeing visual field before and after training. The average fixation duration was significantly shorter after the training, but only in the experimental training

  8. An Investigation of the Strength and Deformation Characteristics of Rock masses: A Case Study in an Excavation of Eskişehir-Köseköy Tunnels, Turkey

    Science.gov (United States)

    Beyhan, Sunay; Abiddin Erguler, Zeynal; Ogul, Kenan

    2015-04-01

    With increasing of high-speed rail technology in last decades, Turkey has developed many big engineering projects to connect major cities. Excavations conducted for these projects provide very important contributions in term of understanding the strength and deformation characteristics of weak rock masses belongs to various geological materials. The Ankara-Istanbul high-speed railway known as a significant project among these projects was designed in two different phases. To discuss the outcomes, experiences and challenging geological materials during construction of this tunnel, the geotechnical properties of rock masses of a tunnel named as T19 are evaluated and discussed in this study. The T19 tunnel was excavated in stratified and heavily fractured four different geological formations. Rock mass rating (RMR) system, and tunnelling quality index (Q) were utilized for the preliminary design stages of this tunnel. These engineering rock mass classifications were utilized in 135 different locations to find representative RMR and Q values for encountered rock masses during excavation. The RMR and Q values, which range between 18-52 and changing between 0.017 and 1.6 respectively, indicate that the T19 tunnel was mainly constructed in very poor and poor rock masses. Thus, shotcrete immediately was applied after face advance to prevent the fall of loose rock fragments and to minimize excessive deformation in rock, particular in very poor and poor rock masses. In addition, the deformation characteristics of the tunnel were also carefully monitored and measured by 3D-optical measuring system and conventional tape extensometer, and then required further supports were installed. Finally, the rock mass-support interactions of different geological formations were comprehensively evaluated in this study for understanding strength and deformation characteristics of weak and stratified rock masses. Keywords: Convergence, high-speed rail, rock mass, support, tunnel

  9. Terthiophene on Au(111: A scanning tunneling microscopy and spectroscopy study

    Directory of Open Access Journals (Sweden)

    Berndt Koslowski

    2011-09-01

    Full Text Available Terthiophene (3T molecules adsorbed on herringbone (HB reconstructed Au(111 surfaces in the low coverage regime were investigated by means of low-temperature scanning tunneling microscopy (STM and spectroscopy (STS under ultra-high vacuum conditions. The 3T molecules adsorb preferentially in fcc regions of the HB reconstruction with their longer axis oriented perpendicular to the soliton walls of the HB and at maximum mutual separation. The latter observation points to a repulsive interaction between molecules probably due to parallel electrical dipoles formed during adsorption. Constant-separation (I-V and constant-current (z-V STS clearly reveal the highest occupied (HOMO and lowest unoccupied (LUMO molecular orbitals, which are found at −1.2 eV and +2.3 eV, respectively. The HOMO–LUMO gap corresponds to that of a free molecule, indicating a rather weak interaction between 3T and Au(111. According to conductivity maps, the HOMO and LUMO are inhomogeneously distributed over the adsorbed 3T, with the HOMO being located at the ends of the linear molecule, and the LUMO symmetrically with respect to the longer axis of the molecule at the center of its flanks. Analysis of spectroscopic data reveals details of the contrast mechanism of 3T/Au(111 in STM. For that, the Shockley-like surface state of Au(111 plays an essential role and appears shifted outwards from the surface in the presence of the molecule. As a consequence, the molecule can be imaged even at a tunneling bias within its HOMO–LUMO gap. A more quantitative analysis of this detail resolves a previous discrepancy between the fairly small apparent STM height of 3T molecules (1.4–2.0 nm, depending on tunneling bias and a corresponding larger value of 3.5 nm based on X-ray standing wave analysis. An additionally observed linear decrease of the differential tunneling barrier at positive bias when determined on top of a 3T molecule is compared to the bias independent barrier obtained on

  10. Surface Morphology and Overlayer Formation Kinetics of OXYGEN/SILVER(110) Studied by Scanning Tunneling Microscopy

    Science.gov (United States)

    Pai, Woei Wu.

    1995-01-01

    I have applied scanning tunneling microscopy (STM) to study clean and oxygen-covered vicinal Ag(110) surfaces at room temperature. Experimental results of surface morphology/stability, surface mass transport and surface chemical reactivity are presented. On clean vicinal Ag(110) surfaces, the steps distribute under the influence of step-step interactions. The terrace width distributions indicate an additional oscillatory component besides an l^{-2} interaction term. If the surface is contaminated slightly (quasi-clean), isolated "pinning sites" impede the motion of steps. The interactions between steps push the steps across the pinning site, resulting in a curved step front. When oxygen atoms adsorb on stepped Ag(110), a dramatic change in surface morphology occurs. The surface separates into two distinct phases--step bunches and large terraces (facets). The orientational instability is closely related to the linear "added-row" structure of the oxygen overlayer, as the long O chains push steps into bunches. The O chains do not push the steps effectively when O chains orient perpendicular to steps, and the faceting proceeds through nucleation. If the O chains orient near parallel to steps, however, O chains push the steps easily and the faceting proceeds through spinodal decomposition. To understand the mass transport during faceting, I quantify the thermal step fluctuations by employing a Langevin statistical analysis. The mass transport mechanism at the step edge is shown to be by atomic exchange between steps and terraces, making the step an effective source or sink for Ag adatoms. This Ag source also proves essential in O overlayer formation, since both Ag and O atoms are incorporated into the "added -row" overlayer structure. Because an Ag source must be found during the adlayer formation, I show the surface morphology is sensitive to oxygen dosing pressure. Above a critical O pressure of 10^{-5} mbar, vacancy islands on terraces provide a second source of Ag

  11. Laser reflection spot as a pattern in a diamond coating – a microscopic study

    Directory of Open Access Journals (Sweden)

    GORDANA S. RISTIĆ

    2009-07-01

    Full Text Available Diamond coatings were deposited by the synchronous and coupled action of a hot filament CVD method and a pulsed CO2 laser in spectro-absorbing and spectro-non-absorbing diamond precursor atmospheres. The obtained coatings were structured/patterned, i.e., they were comprised of uncovered, bare locations. An extra effect observed only in the spectro-active diamond precursor atmosphere was the creation of another laser spot in the coating – a reflection spot. In order to establish the practical usability of the latter one, extensive microscopic investigations were performed with consideration of the morphology changes in the spot of the direct laser beam. Normal incidence SEM images of this spot showed a smooth surface, without any pulse radiation damage. AFM imaging revealed the actual surface condition and gave precise data on the surface characteristics.

  12. Electron microscope study of the genesis of strain-induced martensite embryos

    International Nuclear Information System (INIS)

    Staudhammer, K.P.; Hecker, S.S.; Murr, L.E.

    1984-01-01

    Previous work of Olson and Cohen and Murr, et al., is used to describe the genesis of martensite embryos which form at the intersection of microscopic shear bands in deformed type 304 stainless steel. It is shown that the intersection volume included within intersecting shear bands contains irregular and smaller dispersed volume segments forming α' martensite (bcc). These correspond to the satisfaction of specific intersections of stacking faults or partial dislocations on approximately every second (111)/sub fcc/ plane in one direction, and every third (111)/sub fcc/ plane in the other (conjugate) direction. The requisite stacking fault or partial dislocation arrangements are produced in an irregular fashion resulting in α' martensite embryos nucleating in an incomplete and irregular fashion within the intersection volume. 9 references, 2 figures

  13. Microscopic study of {sup 6}He elastic scattering around the Coulomb barrier

    Energy Technology Data Exchange (ETDEWEB)

    Descouvemont, P. [Physique Nucléaire Théorique et Physique Mathématique, C.P. 229, Université Libre de Bruxelles (ULB), B 1050 Brussels (Belgium)

    2016-07-07

    We investigate {sup 6}He scattering on {sup 27}Al, {sup 58}Ni, {sup 120}Sn, and {sup 208}Pb in a microscopic version of the Continuum Discretized Coupled Channel (CDCC) method. We essentially focus on energies around the Coulomb barrier. The {sup 6}He nucleus is described by an antisymmetric 6-nucleon wave function, defined in the Resonating Group Method. The {sup 6}He continuum is simulated by square-integrable positive-energy states. The model does not depend on any adjustable parameter as it is based only on well known nucleon-target potentials. We show that experimental elastic cross sections are fairly well reproduced. The calculation suggests that breakup effects increase for high target masses. For a light system such as {sup 6}He+{sup 27}Al, breakup effects are small, and a single-channel approximation provides fair results.

  14. Novel biaxial tensile test for studying aortic failure phenomena at a microscopic level

    Directory of Open Access Journals (Sweden)

    Sugita Shukei

    2013-01-01

    Full Text Available Abstract Background An aortic aneurysm is a local dilation of the aorta, which tends to expand and often results in a fatal rupture. Although larger aneurysms have a greater risk of rupture, some small aneurysms also rupture. Since the mechanism of aortic rupture is not well understood, clarification of the microstructure influencing the failure to rupture is important. Since aortic tissues are stretched biaxially in vivo, we developed a technique to microscopically observe the failure of an aortic rupture during biaxial stretch. Methods A thinly sliced porcine thoracic aortic specimen was adhered to a circular frame and pushed onto a cylinder with a smaller diameter to stretch the specimen biaxially. To induce failure to rupture at the center, the specimen was thinned at the center of the hole as follows: the specimen was frozen while being compressed with metal plates having holes, which were 3 mm in diameter at their centers; the specimen was then sliced at 50-μm intervals and thawed. Results The ratio of the thickness at the center to the peripheral area was 99.5% for uncompressed specimens. The ratio decreased with an increase in the compression ratio εc and was 47.3% for specimens with εc = 40%. All specimens could be stretched until failure to rupture. The probability for crack initiation within the cylinder was εc εc >30%, respectively. Among specimens ruptured within the cylinder, 93% of those obtained from the mid-media showed crack initiation at the thin center area. Conclusions Aortic tissues were successfully stretched biaxially until failure, and their crack initiation points were successfully observed under a microscope. This could be a very useful and powerful method for clarifying the mechanism of aortic rupture. We are planning to use this technique for a detailed investigation of events occurring at the point of failure when the crack initiates in the aortic aneurysm wall.

  15. Subluxation of the peroneus long tendon in the cuboid tunnel: is it normal or pathologic? An ultrasound and magnetic resonance imaging study

    International Nuclear Information System (INIS)

    Stone, Taylor J.; Rosenberg, Zehava S.; Ciavarra, Gina; Bencardino, Jenny T.; Velez, Zoraida Restrepo; Prost, Roberto

    2016-01-01

    To evaluate the position of the peroneus longus (PL) tendon relative to the cuboid tuberosity and cuboid tunnel during ankle dorsiflexion and plantarflexion using ultrasound and MRI. The study population included two groups: 20 feet of 10 asymptomatic volunteers who underwent prospective dynamic ultrasound and 55 ankles found through retrospective review of routine ankle MRI examinations. The location of the PL tendon at the cuboid tuberosity and cuboid tunnel was designated as completely within the tunnel, indeterminate, or subluxed with respect to ankle dorsiflexion and plantarflexion. On dynamic ultrasound, the PL tendon was perched plantar to the cuboid tuberosity in dorsiflexion, and glided to enter the cuboid tunnel distal to the tuberosity in plantarflexion in all 20 feet. On the MRI evaluation, there was a statistically significant difference (p = 0.0006) in the location of the PL tendon between the ankles scanned in dorsiflexion and plantarflexion. Based on our findings on ultrasound and MRI, the PL tendon can glide in and out of the cuboid tunnel along the cuboid tuberosity depending on ankle position. Thus, ''subluxation'' of the tendon as it curves to enter the cuboid tunnel, which to the best of our knowledge has not yet been described, should be recognized as a normal, position-dependent phenomenon and not be reported as pathology. (orig.)

  16. Subluxation of the peroneus long tendon in the cuboid tunnel: is it normal or pathologic? An ultrasound and magnetic resonance imaging study

    Energy Technology Data Exchange (ETDEWEB)

    Stone, Taylor J. [Charlotte Radiology, Charlotte, NC (United States); Rosenberg, Zehava S.; Ciavarra, Gina; Bencardino, Jenny T. [New York Langone Medical Center / Hospital for Joint Diseases, New York, NY (United States); Velez, Zoraida Restrepo [Cedimed-Dinamica, Medellin (Colombia); Prost, Roberto [Marino Hospital ASL Cagliari, Cagliari (Italy)

    2016-03-15

    To evaluate the position of the peroneus longus (PL) tendon relative to the cuboid tuberosity and cuboid tunnel during ankle dorsiflexion and plantarflexion using ultrasound and MRI. The study population included two groups: 20 feet of 10 asymptomatic volunteers who underwent prospective dynamic ultrasound and 55 ankles found through retrospective review of routine ankle MRI examinations. The location of the PL tendon at the cuboid tuberosity and cuboid tunnel was designated as completely within the tunnel, indeterminate, or subluxed with respect to ankle dorsiflexion and plantarflexion. On dynamic ultrasound, the PL tendon was perched plantar to the cuboid tuberosity in dorsiflexion, and glided to enter the cuboid tunnel distal to the tuberosity in plantarflexion in all 20 feet. On the MRI evaluation, there was a statistically significant difference (p = 0.0006) in the location of the PL tendon between the ankles scanned in dorsiflexion and plantarflexion. Based on our findings on ultrasound and MRI, the PL tendon can glide in and out of the cuboid tunnel along the cuboid tuberosity depending on ankle position. Thus, ''subluxation'' of the tendon as it curves to enter the cuboid tunnel, which to the best of our knowledge has not yet been described, should be recognized as a normal, position-dependent phenomenon and not be reported as pathology. (orig.)

  17. Subluxation of the peroneus long tendon in the cuboid tunnel: is it normal or pathologic? An ultrasound and magnetic resonance imaging study.

    Science.gov (United States)

    Stone, Taylor J; Rosenberg, Zehava S; Velez, Zoraida Restrepo; Ciavarra, Gina; Prost, Roberto; Bencardino, Jenny T

    2016-03-01

    To evaluate the position of the peroneus longus (PL) tendon relative to the cuboid tuberosity and cuboid tunnel during ankle dorsiflexion and plantarflexion using ultrasound and MRI. The study population included two groups: 20 feet of 10 asymptomatic volunteers who underwent prospective dynamic ultrasound and 55 ankles found through retrospective review of routine ankle MRI examinations. The location of the PL tendon at the cuboid tuberosity and cuboid tunnel was designated as completely within the tunnel, indeterminate, or subluxed with respect to ankle dorsiflexion and plantarflexion. On dynamic ultrasound, the PL tendon was perched plantar to the cuboid tuberosity in dorsiflexion, and glided to enter the cuboid tunnel distal to the tuberosity in plantarflexion in all 20 feet. On the MRI evaluation, there was a statistically significant difference (p = 0.0006) in the location of the PL tendon between the ankles scanned in dorsiflexion and plantarflexion. Based on our findings on ultrasound and MRI, the PL tendon can glide in and out of the cuboid tunnel along the cuboid tuberosity depending on ankle position. Thus, "subluxation" of the tendon as it curves to enter the cuboid tunnel, which to the best of our knowledge has not yet been described, should be recognized as a normal, position-dependent phenomenon and not be reported as pathology.

  18. Adsorbate structures and catalytic reactions studied in the torrpressure range by scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Hwang, Kevin Shao-Lin [Univ. of California, Berkeley, CA (United States)

    2003-01-01

    High-pressure, high-temperature scanning tunneling microscopy (HPHTSTM) was used to study adsorbate structures and reactions on single crystal model catalytic systems. Studies of the automobile catalytic converter reaction [CO + NO → 1/2 N2 + CO2] on Rh(111) and ethylene hydrogenation [C2H4 + H2 → C2H6] on Rh(111) and Pt(111) elucidated information on adsorbate structures in equilibrium with high-pressure gas and the relationship of atomic and molecular mobility to chemistry. STM studies of NO on Rh(111) showed that adsorbed NO forms two high-pressure structures, with the phase transformation from the (2 x 2) structure to the (3 x 3) structure occurring at 0.03 Torr. The (3 x 3) structure only exists when the surface is in equilibrium with the gas phase. The heat of adsorption of this new structure was determined by measuring the pressures and temperatures at which both (2 x 2) and (3 x 3) structures coexisted. The energy barrier between the two structures was calculated by observing the time necessary for the phase transformation to take place. High-pressure STM studies of the coadsorption of CO and NO on Rh(111) showed that CO and NO form a mixed (2 x 2) structure at low NO partial pressures. By comparing surface and gas compositions, the adsorption energy difference between topsite CO and NO was calculated. Occasionally there is exchange between top-site CO and NO, for which we have described a mechanism for. At high NO partial pressures, NO segregates into islands, where the phase transformation to the (3 x 3) structure occurs. The reaction of CO and NO on Rh(111) was monitored by mass spectrometry (MS) and HPHTSTM. From MS studies the apparent activation energy of the catalytic converter reaction was calculated and compared to theory. STM showed that under high-temperature reaction conditions, surface metal atoms become mobile. Ethylene hydrogenation and its poisoning by CO was

  19. Carpal Tunnel Syndrome

    Science.gov (United States)

    ... a passing cramp? It could be carpal tunnel syndrome. The carpal tunnel is a narrow passageway of ... three times more likely to have carpal tunnel syndrome than men. Early diagnosis and treatment are important ...

  20. Experimental and Theoretical Study of Air Flow with Obstruction Through Test Section of Wind Tunnel

    Directory of Open Access Journals (Sweden)

    Hayder Kraidy Rashid

    2016-03-01

    Full Text Available This paper estimates the sound and flow generated by a turbulent air flow in a duct from the knowledge of mean quantities (average velocity and sound pressure level.The sound excitation by fluid flow through duct can be used to predict fluid behavior. This behavior can be carried out by discovering the relation between sound excitation and fluid flow parameters like Reynolds number, Strouhal number and frequencies of turbulent fluid flow. However, the fluid flow container stability has to be taken in account simultaneously with fluid flow effect on sound generation and propagation. The experimental system used in this work is air flow through subsonic wind tunnel duct.The sound pressure levels of air flows through test section of subsonic wind tunnel (at three air flow velocities2.5, 7.3 and 12.5 m/s respectively were carried out experimentally. The sound excitation or generation by air flow throughout the test section of subsonic wind tunnel without any obstruction can't be used to imagine the fluid behavior. To predict fluid flow properties,an infinite cylinder was immersed in order to obstruct the air flow and generate a new source of sound.This case is relevant to a wide range of engineering applications including aircraft landing gear, rail pantographs and automotive side-mirrors. Sound measurements have been taken in an anechoic room at Babylon University. ANSYS program software is used to simulate all experimental results.The experimental and theoretical data that were presented in this paper will give further insight into the underlying sound generation mechanism.In the presented work, the linkage between sound generation and CFD results using thepresented work results and ANSYS simulation results was done.The results discuss the effects of fluid flow parameters such as Reynolds and Strouhal numbers on the sound generation, propagation features and vice-versa. The results are compared with other researchers which give good agreements.

  1. Comparative study on the effectiveness of a corticosteroid injection for carpal tunnel syndrome in patients with and without Raynaud's phenomenon.

    Science.gov (United States)

    Roh, Y H; Noh, J H; Gong, H S; Baek, G H

    2017-12-01

    The aim of this study was to compare the efficacy of a corticosteroid injection for the treatment of carpal tunnel syndrome (CTS) in patients with and without Raynaud's phenomenon. In a prospective study, 139 patients with CTS were treated with a corticosteroid injection (10 mg triamcinolone acetonide); 34 had Raynaud's phenomenon and 105 did not (control group). Grip strength, perception of touch with a Semmes-Weinstein monofilament and the Boston Carpal Tunnel Questionnaires (BCTQ) were assessed at baseline and at six, 12 and 24 weeks after the injection. The Cold Intolerance Severity Score (CISS) questionnaire was also assessed at baseline and 24 weeks after the injection. The two groups had similar baseline BCTQ scores, but the scores in the Raynaud's phenomenon group were significantly higher than those in the control group at 12 and 24 weeks after the injection. Throughout the 24-week follow-up, there were no significant differences in the mean grip strength between the groups, whereas the mean Semmes-Weinstein monofilament sensory index for the control group was significantly higher than that of the Raynaud's phenomenon group. The mean CISSs were not significantly different between the groups at baseline and at 24 weeks. After 24 weeks, 11 patients (32%) in the Raynaud's phenomenon group and 16 (15%) in the control group required carpal tunnel decompression (p = 0.028). Multivariable analysis indicated that concurrent Raynaud's phenomenon (odds ratio (OR) 2.6) and severe electrophysiological grade (OR 2.1) were independently associated with a failure of treatment after a corticosteroid injection. Although considerable improvements in symptoms will probably occur in patients with Raynaud's phenomenon who have CTS, they have higher risk of poor functional outcomes and failure of treatment than those without Raynaud's phenomenon. Cite this article: Bone Joint J 2017;99-B:1637-42. ©2017 The British Editorial Society of Bone & Joint Surgery.

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

    International Nuclear Information System (INIS)

    Allen, C.W.

    1992-01-01

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

  3. The effect of vegetation patterns on Aeolian mass flux at regional scale: a wind tunnel study

    OpenAIRE

    Youssef, Feras; Visser, Saskia M; Karssenberg, Derek; Erpul, Gunay; Cornelis, Wim; Gabriels, Donald; Poortinga, Ate; De Boever, Maarten

    2012-01-01

    ABSTRACT Although insight on the effect of vegetation pattern on Aeolian mass transport is essential for re-planting degraded land, only limited knowledge on this effect is available. The objective of this research was to understand the effect of vegetation design on the Aeolian mass flux inside a single land unit and at the borders among land units. A simulation of Atriplex halimus shrubs inside a wind tunnel was made, and sand redistribution was measured after the application of 200-230 sec...

  4. Quantum tunneling of magnetization in molecular nanomagnet Fe8 studied by NMR

    International Nuclear Information System (INIS)

    Maegawa, Satoru; Ueda, Miki

    2003-01-01

    Magnetization and NMR measurements have been performed for single crystals of molecular magnet Fe8. The field and temperature dependences of magnetization below 25 K are well described in terms of the isolated clusters with the total spin S=10. The stepwise recoveries of 1 H-NMR signals at the level crossing fields caused by the resonant quantum tunneling of magnetization were observed below 400 mK. The recovery of the NMR signals are explained by the fluctuation caused by the transition between the energy states of Fe magnetizations governed by Landau-Zener quantum transitions

  5. BIM Methodology Approach to Infrastructure Design: Case Study of Paniga Tunnel

    Science.gov (United States)

    Osello, Anna; Rapetti, Niccolò; Semeraro, Francesco

    2017-10-01

    Nowadays, the implementation of Building Information Modelling (BIM) in civil design represent a new challenge for the AECO (Architecture, Engineering, Construction, Owner and Operator) world, which will involve the interest of many researchers in the next years. It is due to the incentives of Public Administration and European Directives that aim to improve the efficiency and to enhance a better management of the complexity of infrastructure projects. For these reasons, the goal of this research is to propose a methodology for the use of BIM in a tunnel project, analysing the definition of a correct level of detail (LOD) and the possibility to share information via interoperability for FEM analysis.

  6. Observation of diamond turned OFHC copper using Scanning Tunneling Microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Grigg, D.A.; Russell, P.E.; Dow, T.A.

    1988-12-01

    Diamond turned OFHC copper samples have been observed within the past few months using the Scanning Tunneling Microscope. Initial results have shown evidence of artifacts which may be used to better understand the diamond turning process. The STM`s high resolution capability and three dimensional data representation allows observation and study of surface features unobtainable with conventional profilometry systems. Also, the STM offers a better quantitative means by which to analyze surface structures than the SEM. This paper discusses findings on several diamond turned OFHC copper samples having different cutting conditions. Each sample has been cross referenced using STM and SEM.

  7. Colocalization of fluorescence and Raman microscopic images for the identification of subcellular compartments: a validation study.

    Science.gov (United States)

    Krauß, Sascha D; Petersen, Dennis; Niedieker, Daniel; Fricke, Inka; Freier, Erik; El-Mashtoly, Samir F; Gerwert, Klaus; Mosig, Axel

    2015-04-07

    A major promise of Raman microscopy is the label-free detailed recognition of cellular and subcellular structures. To this end, identifying colocalization patterns between Raman spectral images and fluorescence microscopic images is a key step to annotate subcellular components in Raman spectroscopic images. While existing approaches to resolve subcellular structures are based on fluorescence labeling, we propose a combination of a colocalization scheme with subsequent training of a supervised classifier that allows label-free resolution of cellular compartments. Our colocalization scheme unveils statistically significant overlapping regions by identifying correlation between the fluorescence color channels and clusters from unsupervised machine learning methods like hierarchical cluster analysis. The colocalization scheme is used as a pre-selection to gather appropriate spectra as training data. These spectra are used in the second part as training data to establish a supervised random forest classifier to automatically identify lipid droplets and nucleus. We validate our approach by examining Raman spectral images overlaid with fluorescence labelings of different cellular compartments, indicating that specific components may indeed be identified label-free in the spectral image. A Matlab implementation of our colocalization software is available at .

  8. A low cost mobile phone dark-field microscope for nanoparticle-based quantitative studies.

    Science.gov (United States)

    Sun, Dali; Hu, Tony Y

    2018-01-15

    Dark-field microscope (DFM) analysis of nanoparticle binding signal is highly useful for a variety of research and biomedical applications, but current applications for nanoparticle quantification rely on expensive DFM systems. The cost, size, limited robustness of these DFMs limits their utility for non-laboratory settings. Most nanoparticle analyses use high-magnification DFM images, which are labor intensive to acquire and subject to operator bias. Low-magnification DFM image capture is faster, but is subject to background from surface artifacts and debris, although image processing can partially compensate for background signal. We thus mated an LED light source, a dark-field condenser and a 20× objective lens with a mobile phone camera to create an inexpensive, portable and robust DFM system suitable for use in non-laboratory conditions. This proof-of-concept mobile DFM device weighs less than 400g and costs less than $2000, but analysis of images captured with this device reveal similar nanoparticle quantitation results to those acquired with a much larger and more expensive desktop DFMM system. Our results suggest that similar devices may be useful for quantification of stable, nanoparticle-based activity and quantitation assays in resource-limited areas where conventional assay approaches are not practical. Copyright © 2017 Elsevier B.V. All rights reserved.

  9. Validation study of the Esohisto consensus guidelines for the recognition of microscopic esophagitis (histoGERD Trial).

    Science.gov (United States)

    Schneider, Nora I; Plieschnegger, Wolfgang; Geppert, Michael; Wigginghaus, Bernd; Hoess, Gabriele M; Eherer, Andreas; Wolf, Eva-Maria; Rehak, Peter; Vieth, Michael; Langner, Cord

    2014-05-01

    In patients with gastroesophageal reflux disease (GERD), histology is generally believed to be a tool of limited diagnostic value. Our study aimed to assess the prevalence of microscopic esophageal lesions as defined by the Esohisto consensus guidelines, which have proven high interobserver agreement in previous studies. In the prospective Central European multicenter histoGERD trial, we recruited 1071 individuals (576 females and 495 males; median age, 53 years; range, 15-93 years) undergoing gastroscopy for nonselected reasons. Biopsy material was systematically sampled from above and below the gastroesophageal junction. Overall, histologic diagnosis of mild and severe esophagitis was made in 423 (39.5%) and 296 (27.6%) individuals, respectively, whereas the squamous mucosa of 352 individuals (32.9%) was normal upon histology or showed only insignificant findings. Proliferative changes of the squamous epithelium, in particular basal cell layer hyperplasia, papillary elongation, and intercellular space dilation, were more common than inflammatory cell infiltration. The presence of microscopic esophagitis was associated with male sex (P = .009), patients' symptoms (P = .003), history of proton pump inhibitor intake (P < .001), and the endoscopic diagnosis of esophagitis (P < .001). Notably, among the 450 patients with no endoscopic signs of esophagitis (Los Angeles Category N), 41.8% and 17.1% were identified with mild and severe (microscopic) esophagitis, respectively, indicating higher sensitivity of histologic diagnosis. In conclusion, our data illustrate the value of histology in the workup of patients with reflux disease. We suggest that biopsies should routinely be obtained when patients undergo upper gastrointestinal endoscopy for evaluation of GERD and may particularly be beneficial in patients with nonerosive reflux disease. Copyright © 2014 Elsevier Inc. All rights reserved.

  10. Spin-polarized scanning tunneling microscopy and spectroscopy study of chromium on a Cr(001) surface.

    Science.gov (United States)

    Lagoute, J; Kawahara, S L; Chacon, C; Repain, V; Girard, Y; Rousset, S

    2011-02-02

    Several tens of chromium layers were deposited at 250 °C on a Cr(001) surface and investigated by spin-polarized scanning tunneling microscopy (SP-STM), Auger electron spectroscopy (AES) and scanning tunneling spectroscopy (STS). Chromium is found to grow with a mound-like morphology resulting from the stacking of several monolayers which do not uniformly cover the whole surface of the substrate. The terminal plane consists of an irregular array of Cr islands with lateral sizes smaller than 20 × 20 nm(2). Combined AES and STS measurements reveal the presence of a significant amount of segregants prior to and after deposition. A detailed investigation of the surface shows that it consists of two types of patches. Thanks to STS measurements, the two types of area have been identified as being either chromium pure or segregant rich. SP-STM experiments have evidenced that the antiferromagnetic layer coupling remains in the chromium mounds after deposition and is not significantly affected by the presence of the segregants.

  11. Efficacy of paraffin wax bath for carpal tunnel syndrome: a randomized comparative study

    Science.gov (United States)

    Ordahan, Banu; Karahan, Ali Yavuz

    2017-12-01

    Carpal tunnel syndrome (CTS) is the most frequently diagnosed neuropathy of upper extremity entrapment neuropathies. We aimed to investigate the effectiveness of paraffin therapy in patients with CTS. Seventy patients diagnosed with mild or moderate CTS were randomly divided into two groups as splint treatment (during the night and day time as much as possible for 3 weeks) alone and splint (during the night and day time as much as possible for 3 weeks) + paraffin treatment (five consecutive days a week for 3 weeks). Clinical and electrophysiological assessments were performed before and 3 weeks after treatment. The patients were assessed by using visual analog scale (VAS) for pain, electroneuromyography (ENMG), and Boston Carpal Tunnel Syndrome Questionnaire (BCTSQ). The significant improvement was found in VAS scores in both groups when compared with pretreatment values ( p 0.05), whereas a significant improvement was noted in the BCTQ symptom severity scale score in the splint group ( p 0.05), and the difference in these parameters between the groups was statistically significant ( p Paraffin treatment with splint increases the recovery in functional and electrophysiological parameters.

  12. Performance Evaluation and Design Considerations of Electrically Activated Drain Extension Tunneling GNRFET: A Quantum Simulation Study

    Science.gov (United States)

    Ghoreishi, Seyed Saleh; Yousefi, Reza; Taghavi, Neda

    2017-11-01

    In this paper, a tunneling graphene nanoribbon field effect transistor with electrically activated drain extension, namely, EA-T-GNRFET, is proposed. The proposed structure includes a side gate at the drain side with a constant voltage and length of 0.4 V and 15 nm, respectively. Simulations are performed based on the non-equilibrium Green's function method coupled with the Poisson equation in the mode space representation. This side gate creates an additional step in potential profile at the drain side, which increases and decreases the width of tunneling barrier and leakage current, respectively. Furthermore, the proposed structure has lower drain induced barrier thinning, lower sub-threshold swing (SS) and higher I ON/ I OFF ratio than the conventional structure. Also, other characteristics of the device such as switching delay ( τ ), power delay product (PDP) and unity-gain frequency ( f t) are improved in the proposed device. These advantages make EA-T-GNRFET more suitable for digital and analog applications.

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

    Directory of Open Access Journals (Sweden)

    Zar Chi Thent

    2012-01-01

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

  14. Research on improving performance to metallographic microscopes

    Directory of Open Access Journals (Sweden)

    Teodor Socaciu

    2011-12-01

    Full Text Available Precision optical components from an old optical microscope can be improved and emphasized with a dedicated digital microscope camera. This is an affordable way to obtain a high performance metallographic or biological microscope, with minimum of spending. This paper study those ways and adapts a camera to existing microscopes for researchers use, Optimizing visualization by projecting the image and improving the microscope use by different options of capture and image processing.

  15. Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels by means of a slender wedge probe and direct numerical simulation

    Science.gov (United States)

    Wagner, Alexander; Schülein, Erich; Petervari, René; Hannemann, Klaus; Ali, Syed R. C.; Cerminara, Adriano; Sandham, Neil D.

    2018-05-01

    Combined free-stream disturbance measurements and receptivity studies in hypersonic wind tunnels were conducted by means of a slender wedge probe and direct numerical simulation. The study comprises comparative tunnel noise measurements at Mach 3, 6 and 7.4 in two Ludwieg tube facilities and a shock tunnel. Surface pressure fluctuations were measured over a wide range of frequencies and test conditions including harsh test environments not accessible to measurement techniques such as pitot probes and hot-wire anemometry. Quantitative results of the tunnel noise are provided in frequency ranges relevant for hypersonic boundary layer transition. In combination with the experimental studies, direct numerical simulations of the leading-edge receptivity to fast and slow acoustic waves were performed for the slender wedge probe at conditions corresponding to the experimental free-stream conditions. The receptivity to fast acoustic waves was found to be characterized by an early amplification of the induced fast mode. For slow acoustic waves an initial decay was found close to the leading edge. At all Mach numbers, and for all considered frequencies, the leading-edge receptivity to fast acoustic waves was found to be higher than the receptivity to slow acoustic waves. Further, the effect of inclination angles of the acoustic wave with respect to the flow direction was investigated. The combined numerical and experimental approach in the present study confirmed the previous suggestion that the slow acoustic wave is the dominant acoustic mode in noisy hypersonic wind tunnels.

  16. An evaluation of a combined scanning probe and optical microscope for lunar regolith studies

    Science.gov (United States)

    Yang, S.; Pike, W. T.; Staufer, U.; Claus, D.; Rodenburg, J. M.

    2011-12-01

    The microscopic properties of the lunar regolith such as the shape, the surface texture and the size distribution are required for an understanding of both past surface processes and potential hazards for future human exploration [1]. To reveal the particle morphology at the sub micrometer scale, scanning-probe microscopy (SPM), first used on the 2008 Phoenix mission [1], is a proven approach; however, there are two main challenges for the measurement of lunar particles. Firstly, the SPM tip is liable to move particles during scanning, even when using the lower contact forces of the dynamic-mode imaging. Hence the particles need to be stabilised during imaging. Secondly, typically the AFM tip extends about 10 μm from its cantilever, so larger particles protruding more than this height above their substrates cannot be scanned completely. To immobilize particles and eliminate large particles during SPM scanning, micromachined Si substrates, which have been successfully applied in the Phoenix project for Mars investigation in 2008 [2], have been investigated for lunar analogue material. On these substrates micrometer pits are patterned and serve as traps to enhance the stability of the AFM scanning by grasping the particles. In addition, the diameter of pits can determine the size of dusts to be captured and reduce the adhesion for the larger dust and so eliminate the oversized particles. To extend the imaging range and assist in selecting scan areas for the SPM, we use a type of lensless optical imaging (LOM) which uses ptychographic diffractive imaging [3] to eliminate the restrictions and performance limitations of conventional focusing devices. As a reference, scanning electron microscopy (SEM) which minimizes particle-probe interactions and has the advantage of an extended depth of field, is employed to image the same particle fields at resolutions covering both the SPM and LOM. By comparing the differences and the similarities between SEM and LOM images, the

  17. Efficiency of three different polishing methods on enamel and cementum: A scanning electron microscope study.

    Science.gov (United States)

    Chowdhary, Zoya; Mohan, Ranjana

    2018-01-01

    Tooth polishing is an integral part of clinical dentistry. The main purpose of polishing is to smoothen the surface of the tooth and minimize the deposition of plaque to allow a healthy periodontal maintenance postscaling. Today, polishing by different methods is available to a clinician. Traditional bristle brush and rubber-cup polishing are being widely practiced and gradually getting replaced by novel air polisher. Pros and cons of each method should be weighed before its clinical applications. To evaluate and compare the efficiency of three different polishing systems on enamel as well as on cementum surfaces by scanning electron microscope (SEM). A total of 120 samples were divided into three groups randomly - Group 1 (bristle brush), Group 2 (rubber cup), and Group 3 (air polisher) - with 20 samples each of enamel and cementum, which were subdivided into 10 control and 10 test group (subjected to polishing). The samples were analyzed by SEM at ×1000 magnification, and the data obtained were compiled and subjected to statistical analysis. Polishing with bristle brush demonstrated less surface roughness and debris when compared to air polisher at P = 0.58, P = 0.03 for enamel surface and P = 0.003, P = 0.21 for cementum, respectively. The surface roughness was reduced considerably by rubber cup at P = 0.03 for enamel and P = 0.003 for cementum, compared to air polisher at P = 0.99 and P = 0.21 for enamel and cementum, respectively. The results indicate that polishing with rubber cup was more effective and statistically significant when compared to bristle brush polishing and air polisher for the crown and root surface smoothening and debris removal.

  18. Hyalocytes in idiopathic epiretinal membranes: a correlative light and electron microscopic study.

    Science.gov (United States)

    Schumann, Ricarda G; Gandorfer, Arnd; Ziada, Jean; Scheler, Renate; Schaumberger, Markus M; Wolf, Armin; Kampik, Anselm; Haritoglou, Christos

    2014-12-01

    To describe characteristics of epiretinal cells at the vitreoretinal interface by correlative light and electron microscopy (CLEM). Epiretinal membrane (ERM) specimens and internal limiting membrane (ILM) specimens were harvested by sequential peeling during vitrectomy from 27 eyes with idiopathic epiretinal gliosis, and processed for CLEM. Intraoperatively, the presence of posterior vitreous detachment (PVD) was documented. We used anti-vimentin, anti-α-smooth muscle actin (α-SMA), and anti-CD45 as primary antibodies. A fluorescein-tagged immunonanogold cluster was used as secondary antibody and visualized under the fluorescence and transmission electron microscope. We demonstrated CD45-positive cells specifically labelled at their plasma membranes with ultrastructural features known for hyalocytes, such as oval nucleus with marginal chromatin, vacuoles, dense granules, and thin cytoplasmic protrusions. CD45-positive cells were mostly located on a thick layer of native vitreous collagen. They were covered by newly formed collagen strands with multilayered proliferation of myofibroblasts. We also demonstrated immunoreactivity for vimentin and alpha-SMA. Cell fragments with positive labelling for α-SMA and vimentin were not only found on the vitreal side of the ILM, but also on the retinal side. By CLEM, the majority of CD45-positive cells in epiretinal cell proliferation were characterized as hyalocytes. In the context of anomalous PVD and vitreoschisis, ultrastructural features and topographic localization of hyalocytes suggest that these cells play a significant role in ERM formation. CLEM enables a more accurate characterization of epiretinal cell proliferation, and therefore, contributes to a better understanding of the pathogenesis of diseases at the vitreoretinal interface.

  19. Characteristics of high-transmission-probability tunnel junctions for use as particle detectors

    International Nuclear Information System (INIS)

    Stricker, D.A.; Alba, G.P.; Anderson, C.C.; Bing, D.D.; Bland, R.W.; Dickson, S.C.; Dignan, T.G.; Gagnon, P.; Johnson, R.T.; Seneclauze, C.M.

    1988-01-01

    Interest in the problem of the galactic dark matter has stimulated development of particle detectors sensitive to very low energies. Superconducting tunnel junctions may be useful in such detectors. We describe here superconducting tunnel junctions with thin barriers which may be suitable for this purpose. We present I-V characteristics and data on the temperature dependence of the subgap tunneling current. We also present some scanning-electron-microscope observations of the thin films of the tunnel junctions

  20. Road vehicle emissions of molecular hydrogen (H 2) from a tunnel study

    Science.gov (United States)

    Vollmer, Martin K.; Juergens, Niklas; Steinbacher, Martin; Reimann, Stefan; Weilenmann, Martin; Buchmann, Brigitte

    Motor vehicle combustion emissions of molecular hydrogen (H 2), carbon monoxide (CO), and carbon dioxide (CO 2) were measured during a 6-week period from November 2004 to January 2005 in Gubrist Tunnel, Switzerland, to determine vehicle emission factors for these trace gases and the ratios of the concentration growths ΔH2/ΔCO and ΔH2/ΔCO2 in the tunnel under real-world highway driving conditions. For H 2, molar mixing ratios at the tunnel exit were found to be 7-10 ppm (parts-per-million, 10-6) during rush hours. Mean emission factors of E=49.7(±16.5)mgkm-1, ECO=1.46(±0.54)gkm-1, and E=266(±69)gkm-1 were calculated. E was largest during weekday rush-hour traffic, a consequence of the more frequent accelerations in congested traffic when fuel combustion is not optimal. E was smaller for heavy-duty vehicles (HDV) compared to light-duty vehicles (LDV), a finding which was attributed to the diesel vs. gasoline engine technology. The mean ΔH2/ΔCO molecular ratio was 0.48±0.12. This ratio increased to ˜0.6 during rush hours, suggesting that H 2 yield is favored relative to CO under fuel-rich conditions, presumably a consequence of an increasing contribution of the water-gas-shift reaction. The mean ΔH2/ΔCO2 molecular ratio was 4.4×10-3 but reduced to 2.5×10-3 when the relative HDV abundance was at maximum. Using three different approaches, road traffic H 2 emissions were estimated for 2004 for Switzerland at 5.0-6.6 Gg and globally at 4.2-8.1 Tg. Despite projections of increasing traffic, Swiss H 2 emissions are not expected to change significantly in the near future, and global emissions are likely to decrease due to improved exhaust gas clean-up technologies.