WorldWideScience

Sample records for aberration-corrected scanning transmission

  1. Aberration corrected Lorentz scanning transmission electron microscopy

    We present results from an aberration corrected scanning transmission electron microscope which has been customised for high resolution quantitative Lorentz microscopy with the sample located in a magnetic field free or low field environment. We discuss the innovations in microscope instrumentation and additional hardware that underpin the imaging improvements in resolution and detection with a focus on developments in differential phase contrast microscopy. Examples from materials possessing nanometre scale variations in magnetisation illustrate the potential for aberration corrected Lorentz imaging as a tool to further our understanding of magnetism on this lengthscale. - Highlights: • Demonstration of nanometre scale resolution in magnetic field free environment using aberration correction in the scanning transmission electron microscope (STEM). • Implementation of differential phase contrast mode of Lorentz microscopy in aberration corrected STEM with improved sensitivity. • Quantitative imaging of magnetic induction of nanostructures in amorphous and cross-section samples

  2. Bright-field imaging of compound semiconductors using aberration-corrected scanning transmission electron microscopy

    Aoki, Toshihiro; Lu, Jing; McCartney, Martha R.; Smith, David J.

    2016-09-01

    This study reports the observation of six different zincblende compound semiconductors in [110] projection using large-collection-angle bright-field (LABF) imaging with an aberration-corrected scanning transmission electron microscope. Phase contrast is completely suppressed when the collection semi-angle is set equal to the convergence semi-angle and there are no reversals in image contrast with changes in defocus or thickness. The optimum focus for imaging closely separated pairs of atomic columns (‘dumbbells’) is unique and easily recognized, and the positions of atomic columns occupied by heavier atoms always have darker intensity than those occupied by lighter atoms. Thus, the crystal polarity of compound semiconductors can be determined unambiguously. Moreover, it is concluded that the LABF imaging mode will be highly beneficial for studying other more complicated heterostructures at the atomic scale.

  3. Aberration-corrected scanning transmission electron microscopy for complex transition metal oxides

    Qing-Hua, Zhang; Dong-Dong, Xiao; Lin, Gu

    2016-06-01

    Lattice, charge, orbital, and spin are the four fundamental degrees of freedom in condensed matter, of which the interactive coupling derives tremendous novel physical phenomena, such as high-temperature superconductivity (high-T c SC) and colossal magnetoresistance (CMR) in strongly correlated electronic system. Direct experimental observation of these freedoms is essential to understanding the structure-property relationship and the physics behind it, and also indispensable for designing new materials and devices. Scanning transmission electron microscopy (STEM) integrating multiple techniques of structure imaging and spectrum analysis, is a comprehensive platform for providing structural, chemical and electronic information of materials with a high spatial resolution. Benefiting from the development of aberration correctors, STEM has taken a big breakthrough towards sub-angstrom resolution in last decade and always steps forward to improve the capability of material characterization; many improvements have been achieved in recent years, thereby giving an in-depth insight into material research. Here, we present a brief review of the recent advances of STEM by some representative examples of perovskite transition metal oxides; atomic-scale mapping of ferroelectric polarization, octahedral distortions and rotations, valence state, coordination and spin ordering are presented. We expect that this brief introduction about the current capability of STEM could facilitate the understanding of the relationship between functional properties and these fundamental degrees of freedom in complex oxides. Project supported by the National Key Basic Research Project, China (Grant No. 2014CB921002), the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No. XDB07030200), and the National Natural Science Foundation of China (Grant Nos. 51522212 and 51421002).

  4. In-situ Study of Dynamic Phenomena at Metal Nanosolder Interfaces Using Aberration Corrected Scanning Transmission Electron Microcopy.

    Lu, Ping

    2014-10-01

    Controlling metallic nanoparticle (NP) interactions plays a vital role in the development of new joining techniques (nanosolder) that bond at lower processing temperatures but remain viable at higher temperatures. The pr imary objective of this project is t o develop a fundamental understanding of the actual reaction processes, associated atomic mechanisms, and the resulting microstructure that occur during thermally - driven bond formation concerning metal - metal nano - scale (<50nm) interfaces. In this LDRD pr oject, we have studied metallic NPs interaction at the elevated temperatures by combining in - situ transmission electron microscopy (TEM ) using an aberration - corrected scanning transmission electron microscope (AC - STEM) and atomic - scale modeling such as m olecular dynamic (MD) simulations. Various metallic NPs such as Ag, Cu and Au are synthesized by chemical routines. Numerous in - situ e xperiments were carried out with focus of the research on study of Ag - Cu system. For the first time, using in - situ STEM he ating experiments , we directly observed t he formation of a 3 - dimensional (3 - D) epitaxial Cu - Ag core - shell nanoparticle during the thermal interaction of Cu and Ag NPs at elevated temperatures (150 - 300 o C). The reaction takes place at temperatures as low as 150 o C and was only observed when care was taken to circumvent the effects of electron beam irradiation during STEM imaging. Atomic - scale modeling verified that the Cu - Ag core - shell structure is energetically favored, and indicated that this phenomenon is a nano - scale effect related to the large surface - to - volume ratio of the NPs. The observation potentially can be used for developing new nanosolder technology that uses Ag shell as the %22glue%22 that stic ks the particles of Cu together. The LDRD has led to several journal publications and numerous conference presentations, and a TA. In addition, we have developed new TEM characterization techniques and phase

  5. Direct imaging of crystal structure and defects in metastable Ge2Sb2Te5 by quantitative aberration-corrected scanning transmission electron microscopy

    Knowledge about the atomic structure and vacancy distribution in phase change materials is of foremost importance in order to understand the underlying mechanism of fast reversible phase transformation. In this Letter, by combining state-of-the-art aberration-corrected scanning transmission electron microscopy with image simulations, we are able to map the local atomic structure and composition of a textured metastable Ge2Sb2Te5 thin film deposited by pulsed laser deposition with excellent spatial resolution. The atomic-resolution scanning transmission electron microscopy investigations display the heterogeneous defect structure of the Ge2Sb2Te5 phase. The obtained results are discussed. Highly oriented Ge2Sb2Te5 thin films appear to be a promising approach for further atomic-resolution investigations of the phase change behavior of this material class

  6. Morphological evolution of InAs/InP quantum wires through aberration-corrected scanning transmission electron microscopy.

    Sales, D L; Varela, M; Pennycook, S J; Galindo, P L; González, L; González, Y; Fuster, D; Molina, S I

    2010-08-13

    Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski-Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of [114] or [118], ending with the formation of mature quantum wires with {114} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calculation of the strain energy during the quantum wire formation process. The observed morphological evolution is explained in terms of the calculated elastic energy changes at the growth front. Regions of the wetting layer close to the nanostructure perimeters have higher strain energy, causing migration of As atoms towards the quantum wire terraces, where the structure is partially relaxed; the thickness of the wetting layer is reduced in these zones and the island height increases until the (001) facet is removed. PMID:20647625

  7. Morphological evolution of InAs/InP quantum wires through aberration-corrected scanning transmission electron microscopy

    Evolution of the size, shape and composition of self-assembled InAs/InP quantum wires through the Stranski-Krastanov transition has been determined by aberration-corrected Z-contrast imaging. High resolution compositional maps of the wires in the initial, intermediate and final formation stages are presented. (001) is the main facet at their very initial stage of formation, which is gradually reduced in favour of {114} or {118}, ending with the formation of mature quantum wires with {114} facets. Significant changes in wire dimensions are measured when varying slightly the amount of InAs deposited. These results are used as input parameters to build three-dimensional models that allow calculation of the strain energy during the quantum wire formation process. The observed morphological evolution is explained in terms of the calculated elastic energy changes at the growth front. Regions of the wetting layer close to the nanostructure perimeters have higher strain energy, causing migration of As atoms towards the quantum wire terraces, where the structure is partially relaxed; the thickness of the wetting layer is reduced in these zones and the island height increases until the (001) facet is removed.

  8. Image transfer with spatial coherence for aberration corrected transmission electron microscopes.

    Hosokawa, Fumio; Sawada, Hidetaka; Shinkawa, Takao; Sannomiya, Takumi

    2016-08-01

    The formula of spatial coherence involving an aberration up to six-fold astigmatism is derived for aberration-corrected transmission electron microscopy. Transfer functions for linear imaging are calculated using the newly derived formula with several residual aberrations. Depending on the symmetry and origin of an aberration, the calculated transfer function shows characteristic symmetries. The aberrations that originate from the field's components, having uniformity along the z direction, namely, the n-fold astigmatism, show rotational symmetric damping of the coherence. The aberrations that originate from the field's derivatives with respect to z, such as coma, star, and three lobe, show non-rotational symmetric damping. It is confirmed that the odd-symmetric wave aberrations have influences on the attenuation of an image via spatial coherence. Examples of image simulations of haemoglobin and Si [211] are shown by using the spatial coherence for an aberration-corrected electron microscope. PMID:27155359

  9. The first observation of titanate nanotubes by spherical aberration corrected high-resolution transmission electron microscopy

    Miao, L.; Tanemura, S.; Jiang, T.; Tanemura, M.; Yoshida, K.; Tanaka, N.; Xu, G.

    2009-07-01

    Multi-wall titanate nanotubes (MW-TNNTs) with high aspect ratio, large surface area and good uniformity were produced by alkaline hydrothermal treatment of grounded TiO 2 aerogels and further by applying freeze-drying. Not only the crystal phase and diameter, but also morphology of the starting materials impact on the aspect ratio and transformation efficiency of the obtained nanotubes. Other parameters, such as pH value during neutralization process and drying method for the final products, are important to control length and dispersion of MW-TNNTs. By spherical aberration corrected high-resolution transmission-electron-microscopy (Cs-corrected HRTEM) with lateral space resolution of 0.14 nm at 200 kV accelerating voltage and electron energy loss spectrum (EELS), the detailed structural analysis of MW-TNNTs reveals that (1) diameters of inner and outer tubes are about 4-7 nm and 10 nm, respectively, (2) numbers of layers are different from part to part along the longitudinal tube axis, (3) the walls of the tubes have interlayer spacing of 0.70-0.80 nm and the lateral fringes which are vertical to the walls have spacing of 0.32 nm, (4) each layer of MW-TNNT is the nanosheet composed by the arrayed TiO 6 octahedrons, and respective octahedron being slightly strained, and (5) no chirality of MW-TNNT tubular structure is observed.

  10. Interaction between single gold atom and the graphene edge: A study via aberration-corrected transmission electron microscopy

    Wang, Hongtao

    2012-01-01

    Interaction between single noble metal atoms and graphene edges has been investigated via aberration-corrected and monochromated transmission electron microscopy. A collective motion of the Au atom and the nearby carbon atoms is observed in transition between energy-favorable configurations. Most trapping and detrapping processes are assisted by the dangling carbon atoms, which are more susceptible to knock-on displacements by electron irradiation. Thermal energy is lower than the activation barriers in transition among different energy-favorable configurations, which suggests electron-beam irradiation can be an efficient way of engineering the graphene edge with metal atoms. © 2012 The Royal Society of Chemistry.

  11. Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

    Akashi, Tetsuya; Takahashi, Yoshio; Tanigaki, Toshiaki, E-mail: toshiaki.tanigaki.mv@hitachi.com; Shimakura, Tomokazu; Kawasaki, Takeshi; Furutsu, Tadao; Shinada, Hiroyuki; Osakabe, Nobuyuki [Central Research Laboratory, Hitachi, Ltd., Hatoyama 350-0395 (Japan); Müller, Heiko; Haider, Maximilian [Corrected Electron Optical Systems GmbH, Englerstr. 28, D-69126 Heidelberg (Germany); Tonomura, Akira [Central Research Laboratory, Hitachi, Ltd., Hatoyama 350-0395 (Japan); RIKEN Center for Emergent Matter Science (CEMS), Wako 351-0198 (Japan)

    2015-02-16

    Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm.

  12. Aberration corrected 1.2-MV cold field-emission transmission electron microscope with a sub-50-pm resolution

    Atomic-resolution electromagnetic field observation is critical to the development of advanced materials and to the unveiling of their fundamental physics. For this purpose, a spherical-aberration corrected 1.2-MV cold field-emission transmission electron microscope has been developed. The microscope has the following superior properties: stabilized accelerating voltage, minimized electrical and mechanical fluctuation, and coherent electron emission. These properties have enabled to obtain 43-pm information transfer. On the bases of these performances, a 43-pm resolution has been obtained by correcting lens aberrations up to the third order. Observations of GaN [411] thin crystal showed a projected atomic locations with a separation of 44 pm

  13. Aberration-corrected transmission electron microscopy analyses of GaAs/Si interfaces in wafer-bonded multi-junction solar cells

    Aberration-corrected scanning transmission electron microscopy (STEM) and electron energy loss spectroscopy (EELS) investigations have been applied to investigate the structure and composition fluctuations near interfaces in wafer-bonded multi-junction solar cells. Multi-junction solar cells are of particular interest since efficiencies well above 40% have been obtained for concentrator solar cells which are based on III-V compound semiconductors. In this methodologically oriented investigation, we explore the potential of combining aberration-corrected high-angle annular dark-field STEM imaging (HAADF-STEM) with spectroscopic techniques, such as EELS and energy-dispersive X-ray spectroscopy (EDXS), and with high-resolution transmission electron microscopy (HR-TEM), in order to analyze the effects of fast atom beam (FAB) and ion beam bombardment (IB) activation treatments on the structure and composition of bonding interfaces of wafer-bonded solar cells on Si substrates. Investigations using STEM/EELS are able to measure quantitatively and with high precision the widths and the fluctuations in element distributions within amorphous interface layers of nanometer extensions, including those of light elements. Such measurements allow the control of the activation treatments and thus support assessing electrical conductivity phenomena connected with impurity and dopant distributions near interfaces for optimized performance of the solar cells. - Highlights: • Aberration-corrected TEM and EELS reveal structural and elemental profiles across GaAs/Si bond interfaces in wafer-bonded GaInP/GaAs/Si - multi-junction solar cells. • Fluctuations in elemental concentration in nanometer-thick amorphous interface layers, including the disrubutions of light elements, are measured using EELS. • The projected widths of the interface layers are determined on the atomic scale from STEM-HAADF measurements. • The effects of atom and ion beam activation treatment on the bonding

  14. Aberration corrected and monochromated environmental transmission electron microscopy: challenges and prospects for materials science

    Hansen, Thomas Willum; Wagner, Jakob Birkedal; Dunin-Borkowski, Rafal E.

    2010-01-01

    The latest generation of environmental transmission electron microscopes incorporates aberration correctors and monochromators, allowing studies of chemical reactions and growth processes with improved spatial resolution and spectral sensitivity. Here, we describe the performance of such an instr...

  15. High-resolution adaptive optics scanning laser ophthalmoscope with dual deformable mirrors for large aberration correction

    Chen, D; Jones, S M; Silva, D A; Olivier, S S

    2007-01-25

    Scanning laser ophthalmoscopes with adaptive optics (AOSLO) have been shown previously to provide a noninvasive, cellular-scale view of the living human retina. However, the clinical utility of these systems has been limited by the available deformable mirror technology. In this paper, we demonstrate that the use of dual deformable mirrors can effectively compensate large aberrations in the human retina, making the AOSLO system a viable, non-invasive, high-resolution imaging tool for clinical diagnostics. We used a bimorph deformable mirror to correct low-order aberrations with relatively large amplitudes. The bimorph mirror is manufactured by Aoptix, Inc. with 37 elements and 18 {micro}m stroke in a 10 mm aperture. We used a MEMS deformable mirror to correct high-order aberrations with lower amplitudes. The MEMS mirror is manufactured by Boston Micromachine, Inc with 144 elements and 1.5 {micro}m stroke in a 3 mm aperture. We have achieved near diffraction-limited retina images using the dual deformable mirrors to correct large aberrations up to {+-} 3D of defocus and {+-} 3D of cylindrical aberrations with test subjects. This increases the range of spectacle corrections by the AO systems by a factor of 10, which is crucial for use in the clinical environment. This ability for large phase compensation can eliminate accurate refractive error fitting for the patients, which greatly improves the system ease of use and efficiency in the clinical environment.

  16. Effect of oxygen stoichiometry in LuFe2O(4-δ) and its microstructure observed by aberration-corrected transmission electron microscopy.

    Yang, H X; Tian, H F; Wang, Z; Qin, Y B; Ma, C; Li, J Q; Cheng, Z Y; Yu, R; Zhu, J

    2012-10-31

    A series of oxygen deficient LuFe(2)O(4-δ) materials have been prepared under a controlled oxygen partial-pressure atmosphere. Measurements of magnetization reveal that the increase of oxygen deficiencies could evidently depress the ferrimagnetic phase transition temperature (T(N)). In additional to the well-known charge ordering within the (11(-)0) crystal plane, a visible structural modulation with q = (0,1/4.2,7/8) commonly appears on the (100) plane in the oxygen deficient samples. An aberration-corrected transmission electron microscopy study on the oxygen deficient samples demonstrates the presence of oxygen vacancies and local structural distortion. The atomic structural features in correlation with the structural modulation, distortion of the FeO(5) polyhedron and the (001) twinning domains have been also examined. PMID:23032863

  17. A ‘jump-to-coalescence’ mechanism during nanoparticle growth revealed by in situ aberration-corrected transmission electron microscopy observations

    Neng, Wan; Shuang-ying, Lei; Jun, Xu; Martini, Matteo

    2016-05-01

    In this work, we used in situ aberration-corrected transmission electron microscopy (AC-TEM) to observe the coalescence of gold nanoparticles. We observed a critical edge-to-edge distance {d}ec∼ 0.5 {nm} below which the two particles will coalesce rapidly (jump-to-coalescence). A model based on the single-atom-triggered rapid particle contraction was proposed and verified by first-principles calculations, in which evident energy decrease was detected when adding a gold atom between two gold nanoparticles. Our ex situ TEM study of sputtering-deposited gold nanoparticles on different substrates with varied time also supports the jump-to-contact mechanism. This observation afforded physical insight into the fundamental growth mechanism during dynamic particle coalescence processes.

  18. Aberration Corrected Emittance Exchange

    Nanni, Emilio A

    2015-01-01

    Full exploitation of emittance exchange (EEX) requires aberration-free performance of a complex imaging system including active radio-frequency (RF) elements which can add temporal distortions. We investigate the performance of an EEX line where the exchange occurs between two dimensions with normalized emittances which differ by orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dog-leg emittance exchange setup with a 5 cell RF deflector cavity. Aberration correction is performed on the four most dominant aberrations. These include temporal aberrations that are corrected with higher order magnetic optical elements located where longitudinal and transverse emittance are coupled. We demonstrate aberration-free performance of emittances differing by 4 orders of magnitude, i.e. an initial transverse emittance of $\\epsilon_x=1$ pm-rad is exchanged with a longitudinal emittance of $\\epsilon_z=10$ nm-rad.

  19. Evaluation of stacking faults and associated partial dislocations in AlSb/GaAs (001) interface by aberration-corrected high-resolution transmission electron microscopy

    The stacking faults (SFs) in an AlSb/GaAs (001) interface were investigated using a 300 kV spherical aberration-corrected high-resolution transmission electron microscope (HRTEM). The structure and strain distribution of the single and intersecting (V-shaped) SFs associated with partial dislocations (PDs) were characterized by the [110] HRTEM images and geometric phase analysis, respectively. In the biaxial strain maps εxx and εyy, a SF can be divided into several sections under different strain states (positive or negative strain values). Furthermore, the strain state for the same section of a SF is in contrast to each other in εxx and εyy strain maps. The modification in the strain states was attributed to the variation in the local atomic displacements for the SF in the AlSb film on the GaAs substrate recorded in the lattice image. Finally, the single SF was found to be bounded by two 30° PDs. A pair of 30° PDs near the heteroepitaxial interface reacted to form a Lomer-Cottrell sessile dislocation located at the vertices of V-shaped SFs with opposite screw components. The roles of misfit dislocations, such as the PDs, in strain relaxation were also discussed

  20. Brief history of the Cambridge STEM aberration correction project and its progeny

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper “In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday”, recently published in Ultramicroscopy. - Highlights: • We provide a brief history of the Cambridge project to correct the spherical aberration of the scanning transmission electron microscope (STEM). • We describe the project in the full context of other aberration correction work and related research. • We summarize our corrector development work that followed the Cambridge project, and which was the first to reach higher spatial resolution than any non-corrected electron microscope

  1. Brief history of the Cambridge STEM aberration correction project and its progeny

    Brown, L. Michael [Cavendish Laboratory, University of Cambridge, J.J. Thomson Avenue, Cambridge CB3 0HE (United Kingdom); Batson, Philip E. [Institute for Advanced Materials, Devices and Nanotechnology, Rutgers University, Piscataway, NJ 08854 (United States); Department of Physics, Rutgers University, Piscataway, NJ 08854 (United States); Department of Materials Science, Rutgers University, Piscataway, NJ 08854 (United States); Dellby, Niklas [Nion Company, 11515 NE 118th Street, Kirkland, WA 98034 (United States); Krivanek, Ondrej L. [Nion Company, 11515 NE 118th Street, Kirkland, WA 98034 (United States); Department of Physics, Arizona State University, Tempe, AZ 85287 (United States)

    2015-10-15

    We provide a brief history of the project to correct the spherical aberration of the scanning transmission electron microscope (STEM) that started in Cambridge (UK) and continued in Kirkland (WA, USA), Yorktown Heights (NY, USA), and other places. We describe the project in the full context of other aberration correction research and related work, partly in response to the incomplete context presented in the paper “In quest of perfection in electron optics: A biographical sketch of Harald Rose on the occasion of his 80th birthday”, recently published in Ultramicroscopy. - Highlights: • We provide a brief history of the Cambridge project to correct the spherical aberration of the scanning transmission electron microscope (STEM). • We describe the project in the full context of other aberration correction work and related research. • We summarize our corrector development work that followed the Cambridge project, and which was the first to reach higher spatial resolution than any non-corrected electron microscope.

  2. Aberration-corrected STEM and EELS of semiconducting nanostructures

    We review some applications of aberration–corrected electron microscopy for the detailed characterization of semiconducting nanostructures using a combination of high-angle annular dark-field scanning transmission electron microscopy and electron energy loss spectroscopy. The study of self-assembled quantum wires shows that it is possible to determine the composition of the nanostructures with better than 1 nm resolution down to the atomic level while the contrast in the high-angle annular dark-field images is used to determine the presence of wetting layers separating quantum wires and the strain field arising from the local compositional changes. The local measurements of energy loss spectra demonstrate the shift of plasmon peaks consistent with the changes in lattice parameters. High-angle annular dark-field images are also used to study the contrast in GaSb thin films deposited and study the presence of anti-phase domain boundaries. These examples show that aberration-corrected microscopy combined with electron energy loss spectroscopy provide not only enhanced resolution but also increased sensitivity to atomic site compositional changes.

  3. New Views of Materials through Aberration-Corrected STEM

    Pennycook, Stephen J [ORNL; Chisholm, Matthew F [ORNL; Lupini, Andrew R [ORNL; Varela del Arco, Maria [ORNL; Borisevich, Albina Y [ORNL; Pantelides, Sokrates T. [Vanderbilt University; van Benthem, Klaus [ORNL; Shibata, Naoya [University of Tokyo, Tokyo, Japan; Molina Rubio, Sergio I [ORNL; Rashkeev, Sergey [ORNL

    2009-01-01

    The successful correction of lens aberrations in scanning transmission electron microscopy has allowed an improvement in resolution by a factor of two in just a few years. The benefits for materials research are far greater than a factor of two might imply, because enhanced resolution also brings enhanced image contrast, and therefore a vast increase in sensitivity to single atoms, both for imaging and electron energy loss spectroscopy. In addition, aberration correction enables simultaneous, aberrationcorrected, Z-contrast and phase contrast imaging, and brings a depth resolution at the nanometer level. It becomes possible to focus directly on features at different depths in the specimen thickness, and three-dimensional information can be extracted with single atom sensitivity. In conjunction with density functional and elasticity theory, these advances provide a new level of insight into the atomistic origins of materials properties. Several examples are discussed that illustrate the potential for applications, including the segregation of rare earth elements to grain boundaries in Si3N4 ceramics, the quantitative analysis of strain-induced growth phenomena in semiconductor quantum wells, the explanation of the enhanced thermal stability of La-doped -alumina as a catalyst support, and the origin of the remarkable catalytic activity of Au nanoparticles.

  4. Optical advantages of astigmatic aberration corrected heliostats

    van Rooyen, De Wet; Schöttl, Peter; Bern, Gregor; Heimsath, Anna; Nitz, Peter

    2016-05-01

    Astigmatic aberration corrected heliostats adapt their shape in dependence of the incidence angle of the sun on the heliostat. Simulations show that this optical correction leads to a higher concentration ratio at the target and thus in a decrease in required receiver aperture in particular for smaller heliostat fields.

  5. Catadioptric aberration correction in cathode lens microscopy

    Tromp, R.M. [IBM T.J. Watson Research Center, PO Box 218, Yorktown Heights, NY 10598 (United States); Kamerlingh Onnes Laboratory, Leiden Institute of Physics, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2015-04-15

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed.

  6. Catadioptric aberration correction in cathode lens microscopy

    In this paper I briefly review the use of electrostatic electron mirrors to correct the aberrations of the cathode lens objective lens in low energy electron microscope (LEEM) and photo electron emission microscope (PEEM) instruments. These catadioptric systems, combining electrostatic lens elements with a reflecting mirror, offer a compact solution, allowing simultaneous and independent correction of both spherical and chromatic aberrations. A comparison with catadioptric systems in light optics informs our understanding of the working principles behind aberration correction with electron mirrors, and may point the way to further improvements in the latter. With additional developments in detector technology, 1 nm spatial resolution in LEEM appears to be within reach. - Highlights: • The use of electron mirrors for aberration correction in LEEM/PEEM is reviewed. • A comparison is made with similar systems in light optics. • Conditions for 1 nm spatial resolution are discussed

  7. Aberration corrected environmental STEM (AC ESTEM) for dynamic in-situ gas reaction studies of nanoparticle catalysts

    Environmental scanning transmission electron microscopy (ESTEM) with aberration correction (AC) has recently been added to the capabilities of the more established ETEM for analysis of heterogeneous nanoparticle based catalysts. It has helped to reveal the importance and potentially unique properties of individual atoms as active sites in their own right as well as pathways between established nanoparticles. A new capability is introduced for dynamic in-situ experiments under controlled conditions of specimen temperature and gas environment related to real world conditions pertinent to a range of industrial and societal priorities for new and improved chemical processes, materials, fuels, pharmaceutical products and processes, and in control or remediation of environmental emissions

  8. Aberration-corrected imaging of active sites on industrial catalyst nanoparticles

    Gontard, Lionel Cervera; Chang, L-Y; Hetherington, CJD;

    2007-01-01

    Picture perfect: Information about the local topologies of active sites on commercial nanoparticles can be gained with atomic resolution through spherical-aberration-corrected transmission electron microscopy (TEM). A powder of Pt nanoparticles on carbon black was examined with two advanced TEM...

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

    Sasaki, Takeo, E-mail: tasasaki@jeol.co.jp [EM Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Sawada, Hidetaka; Hosokawa, Fumio [EM Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan); Sato, Yuta; Suenaga, Kazu [Nanotube Research Center, National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba Central 5, Higashi 1-1-1, Tsukuba, Ibaraki 305-8565 (Japan)

    2014-10-15

    The performance of aberration-corrected (scanning) transmission electron microscopy (S/TEM) at an accelerating voltage of 15 kV was evaluated in a low-voltage microscope equipped with a cold-field emission gun and a higher-order aberration corrector. Aberrations up to the fifth order were corrected by the aberration measurement and auto-correction system using the diffractogram tableau method in TEM and Ronchigram analysis in STEM. TEM observation of nanometer-sized particles demonstrated that aberrations up to an angle of 50 mrad were compensated. A TEM image of Si[110] exhibited lattice fringes with a spacing of 0.192 nm, and the power spectrum of the image showed spots corresponding to distances of 0.111 nm. An annular dark-field STEM image of Si[110] showed lattice fringes of (111) and (22¯0) planes corresponding to lattice distances of 0.314 nm and 0.192 nm, respectively. At an accelerating voltage of 15 kV, the developed low-voltage microscope achieved atomic-resolution imaging with a small chromatic aberration and a large uniform phase. - Highlights: • Aberration-corrected STEM/TEM imaging at 15 kV demonstrated lattice fringes of Si[110] single crystal with a spacing of 0.192 nm. • To achieve this performance at a lower accelerating voltage, uniform phase area over 50 mrad is mandatory in Ronchigram and Diffractogram tableau. • This means a higher-order aberration of six-fold astigmatism should be compensated. • In addition, decreasing the effect of chromatic aberration plays an important role for improving the performance of linear scattering component at 15 kV TEM.

  10. Atomic-resolution scanning transmission electron microscopy through 50-nm-thick silicon nitride membranes

    Ramachandra, Ranjan; Demers, Hendrix; de Jonge, Niels

    2011-01-01

    Silicon nitride membranes can be used for windows of environmental chambers for in situ electron microscopy. We report that aberration corrected scanning transmission electron microscopy (STEM) achieved atomic resolution on gold nanoparticles placed on both sides of a 50-nm-thick silicon nitride membrane at 200 keV electron beam energy. Spatial frequencies of 1∕1.2 Å were visible for a beam semi-angle of 26.5 mrad. Imaging though a 100-nm-thick membrane was also tested. The achieved imaging c...

  11. Aberration corrected STEM of iron rhodium nanoislands

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

    2014-06-01

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

  12. Isoplanatic patch size for aberration correction in ultrasonic imaging

    Pilkington, Wayne C.

    Methods and experimental results are described for determination of the region size in an aberrating medium over which a single set of aberration estimates can achieve satisfactory b-scan resolution ( i.e., the isoplanatic patch) using time-shift compensation for aberration correction of ultrasonic transmit and receive beams. Based on twenty percent allowable increases in the -12 dB width of the receive or transmit beam focus using cross-correction compared to self-correction, the isoplanatic patch sizes were found to between 3 and 5 millimeters laterally for a linearly-scanned transducer, and at least 12 millimeters axially for a target distance of 55 millimeters and aberration comparable to human abdominal wall. These sizes depend on the aberration severity, reference site axial position, and allowable resolution degradation with cross-correction. The lateral isoplanatic patch size of a linearly scanned image can be more than doubled to match that of a beam-steered acquisition using aberration estimate position matching relative to the tissue surface. Further expansion of the lateral isoplanatic patch size by an additional 50 to 100 percent for both scanning methods is also shown through propagation path matched cross-correction mapping of aberration estimates. The specific mapping required to achieve the best propagation path match depends on the axial distribution of the aberrating structures, the focal depth being imaged, and the cross-correction distance. The effectiveness of alternate methods to derive propagation path matching maps with and without a priori knowledge of aberrator spatial distribution are contrasted; and a means to dynamically adjust correction maps to maximize isoplanatic patch sizes is proposed and verified. Lateral cross-correction mapping and the map changes required for each cross-correction distance can all be implemented with simple shifting of aberration estimates within the transducer aperture. Therefore, use of optimally mapped

  13. Structural investigation of precipitates with Cu and Zn atomic columns in Al-Mg-Si alloys by aberration-corrected HAADF-STEM

    Precipitates in Al-Mg-Si alloys with Cu addition (∼0.1 wt%) and Zn addition (∼1 wt%) were investigated by aberration corrected high angle annular dark field scanning transmission electron microscopy (HAADF-STEM). Most precipitates had no overall unit cell but contained ordered network of Si atomic columns for both the Cu and the Zn containing precipitates. It was found that both Cu and Zn atomic columns are located at specific sites and producing characteristic local configurations on the Si atomic columns

  14. Three-Dimensional scanning transmission electron microscopy of biological specimens

    De Jonge, Niels

    2010-01-18

    A three-dimensional (3D) reconstruction of the cytoskeleton and a clathrin-coated pit in mammalian cells has been achieved from a focal-series of images recorded in an aberration-corrected scanning transmission electron microscope (STEM). The specimen was a metallic replica of the biological structure comprising Pt nanoparticles 2-3 nm in diameter, with a high stability under electron beam radiation. The 3D dataset was processed by an automated deconvolution procedure. The lateral resolution was 1.1 nm, set by pixel size. Particles differing by only 10 nm in vertical position were identified as separate objects with greater than 20% dip in contrast between them. We refer to this value as the axial resolution of the deconvolution or reconstruction, the ability to recognize two objects, which were unresolved in the original dataset. The resolution of the reconstruction is comparable to that achieved by tilt-series transmission electron microscopy. However, the focal-series method does not require mechanical tilting and is therefore much faster. 3D STEM images were also recorded of the Golgi ribbon in conventional thin sections containing 3T3 cells with a comparable axial resolution in the deconvolved dataset. © 2010 Microscopy Society of America.

  15. Characterization of surface metallic states in SrTiO3 by means of aberration corrected electron microscopy.

    Sánchez-Santolino, G; Tornos, J; Bruno, F Y; Cuellar, F A; Leon, C; Santamaría, J; Pennycook, S J; Varela, M

    2013-04-01

    An unusual conducting surface state can be produced in SrTiO3 substrates by irradiation with Argon ions from a plasma source, at low energy and high doses. The effects of irradiation are analyzed here by atomic force microscopy (AFM) and aberration corrected scanning transmission electron microscopy (STEM) combined with electron energy loss spectroscopy (EELS). Depth sensitive studies demonstrate the existence of a heavily damaged surface layer and an oxygen vacancy rich layer immediately underneath, both induced during the irradiation process. We find a clear dependence of the Ti oxidation state with the depth, with a very intense Ti(3+) component near the surface. Oxygen vacancies act as n-type doping by releasing electrons into the lattice and producing an insulator-to-metal transition, which explains the unusual metallic behavior of these samples. PMID:22940531

  16. Picometre-precision analysis of scanning transmission electron microscopy images of platinum nanocatalysts

    Yankovich, Andrew B.; Berkels, Benjamin; Dahmen, W.; Binev, P.; Sanchez, S. I.; Bradley, S. A.; Li, Ao; Szlufarska, Izabela; Voyles, Paul M.

    2014-06-01

    Measuring picometre-scale shifts in the positions of individual atoms in materials provides new insight into the structure of surfaces, defects and interfaces that influence a broad variety of materials’ behaviour. Here we demonstrate sub-picometre precision measurements of atom positions in aberration-corrected Z-contrast scanning transmission electron microscopy images based on the non-rigid registration and averaging of an image series. Non-rigid registration achieves five to seven times better precision than previous methods. Non-rigidly registered images of a silica-supported platinum nanocatalyst show pm-scale contraction of atoms at a ()/() corner towards the particle centre and expansion of a flat () facet. Sub-picometre precision and standardless atom counting with atom uncertainty in the same scanning transmission electron microscopy image provide new insight into the three-dimensional atomic structure of catalyst nanoparticle surfaces, which contain the active sites controlling catalytic reactions.

  17. Structural transformation of tungsten oxide nanourchins into IF-WS2 nanoparticles: an aberration corrected STEM study

    Leonard-Deepak, Francis; Castro-Guerrero, Carlos Fernando; Mejía-Rosales, Sergio; José-Yacamán, Miguel

    2011-12-01

    IF-WS2 nanoparticles synthesized starting from tungsten oxide nanourchins have been investigated by using aberration corrected scanning transmission electron microscopy (Cs-STEM). The synthesis process produced IF-WS2 nanoparticles of two different and well differentiated ranges of size. High resolution HAADF-STEM images and their comparison with simulated STEM micrographs reveal the predominance of stacking of the type 1T close to the border of the structure; the observation of this kind of stacking, observed previously in IF-MoS2 but never reported before in the case of the IF-WS2 nanostructures, adds a new dimension to the existing understanding of structure and stacking in the case of the nanostructures of transition metal chalcogenides.IF-WS2 nanoparticles synthesized starting from tungsten oxide nanourchins have been investigated by using aberration corrected scanning transmission electron microscopy (Cs-STEM). The synthesis process produced IF-WS2 nanoparticles of two different and well differentiated ranges of size. High resolution HAADF-STEM images and their comparison with simulated STEM micrographs reveal the predominance of stacking of the type 1T close to the border of the structure; the observation of this kind of stacking, observed previously in IF-MoS2 but never reported before in the case of the IF-WS2 nanostructures, adds a new dimension to the existing understanding of structure and stacking in the case of the nanostructures of transition metal chalcogenides. Electronic supplementary information (ESI) available: Raman spectra of the WOx-W18O49 nanourchins, XRD pattern, EDAX spectrum and elemental maps of the IF-WS2 nanoparticles. See DOI: 10.1039/c1nr10862j

  18. Understanding the structure of nanocatalysts with high resolution scanning/transmission electron microscopy

    Nanomaterials including nanoparticles, nanowires and nanotubes play an important role in heterogeneous catalysis. Thanks to the rapid improvement of the electron microscopic techniques and with the advent of aberration corrected electron microscopy as well as theoretical methodologies, the potential effects induced by nanocatalysts are better understood than before by unravelling their atomic structure. A brief introduction to advanced electron microscopic techniques namely aberration corrected scanning transmission electron microscopy (Cs-STEM) is presented and subsequently two examples of nanocatalysts are considered in the present review. The first example will focus on the study of bimetallic/core-shell nanoalloys. In heterogeneous catalysis, catalysts containing two or more metals might show significantly different catalytic properties compared to the parent metals and thus are widely utilized in several catalytic reactions. Atom-by-atom insights of the nanoalloy based catalysts ex: Au-Pd will be described in the present review using a combination of advanced electron microscopic and spectroscopic techniques. A related example on the understanding of bimetallic clusters by HAADF-STEM will also be presented in addition to nanoparticles. In the second case understanding the structure of transition metal chalcogenide based nanocatalysts by HRTEM and aberration corrected STEM, for the case of MoS2 will be discussed. MoS2-based catalysts serve as model catalysts and are employed in the hydrodesulphurisations (HDS) reactions in the removal of sulphur from gasoline and related petrochemical products. They have been studied in various forms including nanowires, nanotubes and nanoplates. Their structure, atomic insights and as a consequence elucidation of their corresponding catalytic activity are thus important

  19. Environmental TEM in an Aberration Corrected Microscope

    Hansen, Thomas Willum; Wagner, Jakob Birkedal

    ‐resolution imaging. A gaseous atmosphere in the pole‐piece gap of the objective lens of the microscope alters both the incoming electron wave prior to interaction with the sample and the outgoing wave below the sample. Whereas conventional TEM samples are usually thin (below 10‐20 nm), the gas in the environmental...... microscope column. The effects of gas on the electron wave in the objective lens are not well understood and needs further attention. Imaging samples with a simple geometry, such as gold particles on a flat graphene substrate and analyzing the variations in contrast, provides a means for understanding the...... results from imaging in various elemental as well as di‐molecular gases and their effect on imaging and spectroscopy in the environmental transmission electron microscope....

  20. Probing core-electron orbitals by scanning transmission electron microscopy and measuring the delocalization of core-level excitations

    Jeong, Jong Seok; Odlyzko, Michael L.; Xu, Peng; Jalan, Bharat; Mkhoyan, K. Andre

    2016-04-01

    By recording low-noise energy-dispersive x-ray spectroscopy maps from crystalline specimens using aberration-corrected scanning transmission electron microscopy, it is possible to probe core-level electron orbitals in real space. Both the 1 s and 2 p orbitals of Sr and Ti atoms in SrTi O3 are probed, and their projected excitation potentials are determined. This paper also demonstrates experimental measurement of the electronic excitation impact parameter and the delocalization of an excitation due to Coulombic beam-orbital interaction.

  1. Aberration-corrected electron microscopy of MnAs and As nanocrystals and voids in annealed (Ga,Mn)As

    Kovács, András; Kasama, Takeshi; Sadowski, J.;

    2011-01-01

    Aberration-corrected transmission electron microscopy is used to study voids and nano-crystalline MnAs and As phases formed during the annealing of Mn-doped GaAs. The effects of defocus and inner annular dark-field detector semi-angle on contrast of the nanocrystals are discussed....

  2. The influence of C{sub s}/C{sub c} correction in analytical imaging and spectroscopy in scanning and transmission electron microscopy

    Zaluzec, Nestor J., E-mail: zaluzec@microscopy.com

    2015-04-15

    Aberration correction in scanning/transmission electron microscopy (S/TEM) owes much to the efforts of a small dedicated group of innovators. Leading that frontier has been Prof. Harald Rose. To date his leadership and dynamic personality has spearheaded our ability to leave behind many of the limitations imposed by spherical aberration (C{sub s}) in high resolution phase contrast imaging. Following shortly behind, has been the development of chromatic aberration correction (C{sub c}) which augments those accomplishments. In this paper we will review and summarize how the combination of C{sub s}/C{sub c} technology enhances our ability to conduct hyperspectral imaging and spectroscopy in today's and future computationally mediated experiments in both thin as well as realistic specimens in vacuo and during in-situ/environmental experiments.

  3. Monochromated scanning transmission electron microscopy

    Full text: Electron energy-loss spectroscopy (EELS) has developed into an established technique for chemical and structural analysis of thin specimens in the (scanning) transmission electron microscope (S)TEM. The energy resolution in EELS is largely limited by the stability of the high voltage supply, by the resolution of the spectrometer and by the energy spread of the source. To overcome this limitation a Wien filter monochromator was recently introduced with commercially available STEMs, offering the advantage to better resolve EELS fine structures, which contain valuable bonding information. The method of atomic resolution Z-contrast imaging within an STEM, utilizing a high-angle annular dark-field (HAADF) detector can perfectly complement the excellent energy resolution, since EELS spectra can be collected simultaneously. In combination with a monochromator microscope not only high spatial resolution images can be recorded but also high energy resolution EELS spectra are attainable. In this work we investigated the STEM performance of a 200 kV monochromated Tecnai F20 with a high resolution Gatan Imaging Filter (HR-GIF). (author)

  4. In-situ environmental (scanning) transmission electron microscopy of catalysts at the atomic level

    Observing reacting single atoms on the solid catalyst surfaces under controlled reaction conditions is a key goal in understanding and controlling heterogeneous catalytic reactions. In-situ real time aberration corrected environmental (scanning) transmission electron microscopy (E(S)TEM permit the direct imaging of dynamic surface and sub-surface structures of reacting catalysts. In this paper in-situ AC ETEM and AC ESTEM studies under controlled reaction environments of oxide catalysts and supported metal nanocatalysts important in chemical industry are presented. They provide the direct evidence of dynamic processes at the oxide catalyst surface at the atomic scale and single atom dynamics in catalytic reactions. The ESTEM studies of single atom dynamics in controlled reaction environments show that nanoparticles act as reservoirs of ad-atoms. The results have important implications in catalysis and nanoparticle studies

  5. Environmental Transmission Electron Microscopy in an Aberration-Corrected Environment

    Hansen, Thomas W.; Wagner, Jakob B.

    2012-01-01

    -resolution imaging. A gaseous atmosphere in the pole-piece gap of the objective lens of the microscope alters both the incoming electron wave prior to interaction with the sample and the outgoing wave below the sample. Whereas conventional TEM samples are usually thin (below 100 nm), the gas in the environmental...

  6. Intrinsic Instability of Aberration-Corrected Electron Microscopes

    Schramm, S M; Tromp, R M

    2012-01-01

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

  7. Phase aberration correction by multi-stencils fast marching method using sound speed image in ultrasound computed tomography

    Qu, Xiaolei; Azuma, Takashi; Lin, Hongxiang; Imoto, Haruka; Tamano, Satoshi; Takagi, Shu; Umemura, Shin-Ichiro; Sakuma, Ichiro; Matsumoto, Yoichiro

    2016-04-01

    Reflection image from ultrasound computed tomography (USCT) system can be obtained by synthetic aperture technique, however its quality is decreased by phase aberration caused by inhomogeneous media. Therefore, phase aberration correction is important to improve image quality. In this study, multi-stencils fast marching method (MSFMM) is employed for phase correction. The MSFMM is an accurate and fast solution of Eikonal equation which considers the refraction. The proposed method includes two steps. First, the MSFMM is used to compute sound propagation time from each element to each image gird point using sound speed image of USCT. Second, synthetic aperture technique is employed to obtain reflection image using the computed propagation time. To evaluate the proposed method, both numerical simulation and phantom experiment were conducted. With regard to numerical simulation, both quantitative and qualitative comparisons between reflection images with and without phase aberration correction were given. In the quantitative comparison, the diameters of point spread function (PSF) in reflection images of a two layer structure were presented. In the qualitative comparison, reflection images of simple circle and complex breast modes with phase aberration correction show higher quality than that without the correction. In respect to phantom experiment, a piece of breast phantom with artificial glandular structure inside was scanned by a USCT prototype, and the artificial glandular structure is able to be visible more clearly in the reflection image with phase aberration correction than in that without the correction. In this study, a phase aberration correction method by the MSFMM are proposed for reflection image of the USCT.

  8. Aberration corrected imaging of a carbon nanotube encapsulated Lindqvist Ion and correlation with Density Functional Theory

    Sloan, J.; Bichoutskaia, E.; Liu, Z.; Kuganathan, N.; Faulques, E.; Suenaga, K.; Shannon, I. J.

    2012-07-01

    80 kV aberration-corrected transmission electron microscopy (AC-TEM) of discrete [W6O19]2- polyoxometalate ions mounted within double walled carbon nanotubes (DWNTs) allow high precision structural studies to be performed. W atom column separations within the octahedral W6 tungsten template can be visualized with sufficient clarity that correlation with full-scale density functional theory (DFT) can be achieved. Calculations performed on the gas phase and DWNT-mounted [W6O19]2- anions show good agreement, in the latter case, with measured separations between pairs of W2 atom columns imaged within equatorial WO6 octahedra and single W atoms within axial WO6 octahedra. Structural data from the tilted chiral encapsulating DWNT was also determined simultaneously with the anion structural measurements, allowing the nanotube conformation to be addressed in the DFT calculations.

  9. An Aberration Corrected Photoemission Electron Microscope at the Advanced Light Source

    Design of a new aberration corrected Photoemission electron microscope PEEM3 at the Advanced Light Source is outlined. PEEM3 will be installed on an elliptically polarized undulator beamline and will be used for the study of complex materials at high spatial and spectral resolution. The critical components of PEEM3 are the electron mirror aberration corrector and aberration-free magnetic beam separator. The models to calculate the optical properties of the electron mirror are discussed. The goal of the PEEM3 project is to achieve the highest possible transmission of the system at resolutions comparable to our present PEEM2 system (50 nm) and to enable significantly higher resolution, albeit at the sacrifice of intensity. We have left open the possibility to add an energy filter at a later date, if it becomes necessary driven by scientific need to improve the resolution further

  10. Adaptive temporal and wavefront aberration correction for ultrafast lasers with a membrane deformable mirror

    Sherman, Leah Bruner

    Two adaptive optic systems for correction of either temporal phase error and wavefront errors for ultrafast pulses are demonstrated. These systems consists of a computer controlled micromachined membrane deformable mirror (MMDM) and a genetic learning algorithm (GA). Nonlinear excitation such as two-photon fluorescence or second harmonic generation are used as feedback to the GA to determine the appropriate correction to apply to the mirror. Two MMDMs are used, a 30 x 8 mm, 39 actuator linear MMDM for pulse-shaping applications and a 15 mm diameter, 37 actuator wavefront MMDM. Linear pre-compensation of self-phase modulation (SPM) was experimentally demonstrated utilizing the linear MMDM in a linear pulse-shaper for ultrafast pulses. The nonlinear nature of SPM makes arbitrary polynomial compensation necessary. Pre-compensation of SPM generated in an optical fiber by a 10 fs pulse reduced the pulse from 30fs to 20fs. We demonstrates adaptive correction with the wavefront MMDM by corrected for coma and astigmatism in a reflective multiphoton scanning microscope. An f1, parabola produces a very tight focus with no aberration when it is perfectly aligned. However, when beam scanning is used for two-dimensional imaging the image is severely aberrated. The MMDM and the GA are able to find the best possible wavefront for aberration correction for each scanning position. The horizontal scanning range was increased from 60 mum without the adaptive correction to 170 mum, ≈3 times the uncorrected scanning range, and the vertical scanning range was increased by a comparable amount. This resulted in an increase in scanning area of 9 times. The wavefront MMDM was also used for adaptive correction of spherical aberration from focusing from air, deep into a water-based sample. This depth-based aberration results from an index of refraction mismatch between the sample and the immersion medium of the objective and occurs regardless of beam scanning or sample scanning. By

  11. In vivo transcostal histotripsy therapy without aberration correction

    This study investigates the in vivo therapeutic capabilities of transcostal histotripsy without using aberration correction mechanisms and its thermal impact on overlying tissues. Non-invasive liver treatments were conducted in eight pigs, with four lesions generated through transcostal windows with full ribcage obstruction and four lesions created through transabdominal windows without rib coverage. Treatments were performed by a 750 kHz focused transducer using 5 cycle pulses at 200 Hz PRF, with estimated in situ peak negative pressures of 13–17 MPa. Temperatures on overlying tissues including the ribs were measured with needle thermocouples inserted superficially beneath the skin. Treatments of approximately 40 min were applied, allowing overlying tissue temperatures to reach saturation. Lesions yielded statistically comparable ablation volumes of 3.6 ± 1.7 cm3 and 4.5 ± 2.0 cm3 in transcostal and transabdominal treatments, respectively. The average temperature increase observed in transcostal treatments was 3.9 ± 2.1 °C, while transabdominal treatments showed an increase of 1.7 ± 1.3 °C. No damage was seen on the ribcage or other overlying tissues. These results indicate that histotripsy can achieve effective treatment through the ribcage in vivo without requiring correction mechanisms, while inducing no substantial thermal effects or damage to overlying tissues. Such capabilities could benefit several non-invasive therapy applications involving transcostal treatment windows. (paper)

  12. Proximity Scanning Transmission Electron Microscopy/Spectroscopy

    Hwang, Ing-Shouh

    2016-01-01

    Here a new microscopic method is proposed to image and characterize very thin samples like few-layer materials, organic molecules, and nanostructures with nanometer or sub-nanometer resolution using electron beams of energies lower than 20 eV. The microscopic technique achieves high resolution through the proximity (or near-field) effect, as in scanning tunneling microscopy (STM), while it also allows detection of transmitted electrons for imaging and spectroscopy, as in scanning transmission electron microscopy (STEM). This proximity transmission electron microscopy (PSTEM) does not require any lens to focus the electron beam. It also allows detailed characterization of the interaction of low-energy electron with materials. PSTEM can operate in a way very similar to scanning tunneling microscopy, which provides high-resolution imaging of geometric and electronic structures of the sample surface. In addition, it allows imaging and characterization of the interior structures of the sample based on the detected...

  13. Migration of Single Iridium Atoms and Tri-iridium Clusters on MgO Surfaces. Aberration-Corrected STEM Imaging and ab-initio Calculations

    Han, Chang W. [Purdue Univ., West Lafayette, IN (United States); Iddir, Hakim [Argonne National Lab. (ANL), Argonne, IL (United States); Uzun, Alper [Koc Univ., Instanbul (Turkey); Curtiss, Larry A. [Argonne National Lab. (ANL), Argonne, IL (United States); Browning, Nigel D. [Pacific Northwest National Lab. (PNNL), Richland, WA (United States); Gates, Bruce C. [Univ. of California, Davis, CA (United States); Ortalan, Volkan [Purdue Univ., West Lafayette, IN (United States)

    2015-11-06

    To address the challenge of fast, direct atomic-scale visualization of the diffusion of atoms and clusters on surfaces, we used aberration-corrected scanning transmission electron microscopy (STEM) with high scan speeds (as little as ~0.1 s per frame) to visualize the diffusion of (1) a heavy atom (Ir) on the surface of a support consisting of light atoms, MgO(100), and (2) an Ir3 cluster on MgO(110). Sequential Z-contrast images elucidate the diffusion mechanisms, including the hopping of Ir1 and the rotational migration of Ir3 as two Ir atoms remain anchored to the surface. Density functional theory (DFT) calculations provided estimates of the diffusion energy barriers and binding energies of the iridium species to the surfaces. The results show how the combination of fast-scan STEM and DFT calculations allow real-time visualization and fundamental understanding of surface diffusion phenomena pertaining to supported catalysts and other materials.

  14. Interfacial atomic structure analysis at sub-angstrom resolution using aberration-corrected STEM

    2014-01-01

    The atomic structure of a SiGe/Si epitaxial interface grown via molecular beam epitaxy on a single crystal silicon substrate was investigated using an aberration-corrected scanning transmittance electron microscope equipped with a high-angle annular dark-field detector and an energy-dispersive spectrometer. The accuracy required for compensation of the various residual aberration coefficients to achieve sub-angstrom resolution with the electron optics system was also evaluated. It was found that the interfacial layer was composed of a silicon single crystal, connected coherently to epitaxial SiGe nanolaminates. In addition, the distance between the dumbbell structures of the Si and Ge atoms was approximately 0.136 nm at the SiGe/Si interface in the [110] orientation. The corresponding fast Fourier transform exhibited a sub-angstrom scale point resolution of 0.78 Å. Furthermore, the relative positions of the atoms in the chemical composition line scan signals could be directly interpreted from the corresponding incoherent high-angle annular dark-field image. PMID:25426003

  15. Prospects for versatile phase manipulation in the TEM: Beyond aberration correction

    In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore possible benefits and methods that could come into existence borrowing from light optics where the so-called spatial light modulators provide programmable phase plates for quite some time now. We demonstrate that a fully controllable phase plate building on Harald Rose's legacy in aberration correction and electron optics in general would open an exciting field of research and applications. - Highlights: • We offer a review of available phase manipulation techniques. • We demonstrate a method for producing Airy waves through aberration manipulation. • We outline hypothetical applications of arbitrary phase manipulation methods

  16. Prospects for versatile phase manipulation in the TEM: Beyond aberration correction

    Guzzinati, Giulio; Clark, Laura; Béché, Armand; Juchtmans, Roeland; Van Boxem, Ruben [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium); Mazilu, Michael [SUPA, School of Physics and Astronomy, University of St Andrews, St Andrews KY16 9SS (United Kingdom); Verbeeck, Jo, E-mail: jo.verbeeck@uantwerpen.be [EMAT, University of Antwerp, Groenenborgerlaan 171, 2020 Antwerp (Belgium)

    2015-04-15

    In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore possible benefits and methods that could come into existence borrowing from light optics where the so-called spatial light modulators provide programmable phase plates for quite some time now. We demonstrate that a fully controllable phase plate building on Harald Rose's legacy in aberration correction and electron optics in general would open an exciting field of research and applications. - Highlights: • We offer a review of available phase manipulation techniques. • We demonstrate a method for producing Airy waves through aberration manipulation. • We outline hypothetical applications of arbitrary phase manipulation methods.

  17. Polyvinylidene fluoride molecules in nanofibers, imaged at atomic scale by aberration corrected electron microscopy.

    Lolla, Dinesh; Gorse, Joseph; Kisielowski, Christian; Miao, Jiayuan; Taylor, Philip L; Chase, George G; Reneker, Darrell H

    2016-01-01

    Atomic scale features of polyvinylidene fluoride molecules (PVDF) were observed with aberration corrected transmission electron microscopy. Thin, self-supporting PVDF nanofibers were used to create images that show conformations and relative locations of atoms in segments of polymer molecules, particularly segments near the surface of the nanofiber. Rows of CF2 atomic groups, at 0.25 nm intervals, which marked the paths of segments of the PVDF molecules, were seen. The fact that an electron microscope image of a segment of a PVDF molecule depended upon the particular azimuthal direction, along which the segment was viewed, enabled observation of twist around the molecular axis. The 0.2 nm side-by-side distance between the two fluorine atoms attached to the same carbon atom was clearly resolved. Morphological and chemical changes produced by energetic electrons, ranging from no change to fiber scission, over many orders of magnitude of electrons per unit area, promise quantitative new insights into radiation chemistry. Relative movements of segments of molecules were observed. Promising synergism between high resolution electron microscopy and molecular dynamic modeling was demonstrated. This paper is at the threshold of growing usefulness of electron microscopy to the science and engineering of polymer and other molecules. PMID:26369731

  18. Identifying different stacking sequences in few-layer CVD-grown Mo S2 by low-energy atomic-resolution scanning transmission electron microscopy

    Yan, Aiming; Chen, Wei; Ophus, Colin; Ciston, Jim; Lin, Yuyuan; Persson, Kristin; Zettl, Alex

    2016-01-01

    Atomically thin Mo S2 grown by chemical vapor deposition (CVD) is a promising candidate for next-generation electronics due to inherent CVD scalability and controllability. However, it is well known that the stacking sequence in few-layer Mo S2 can significantly impact electrical and optical properties. Herein we report different intrinsic stacking sequences in CVD-grown few-layer Mo S2 obtained by atomic-resolution annular-dark-field imaging in an aberration-corrected scanning transmission electron microscope operated at 50 keV. Trilayer Mo S2 displays a new stacking sequence distinct from the commonly observed 2 H and 3 R phases of Mo S2 . Density functional theory is used to examine the stability of different stacking sequences, and the findings are consistent with our experimental observations.

  19. Scanning transmission ion microscopy of polycarbonate nanocapillaries

    Complete text of publication follows. Nanochanneled materials are of a great interest due to their peculiar properties and high potential impact for the fabrication of nanostructures and nanodevices. Polycarbonate membranes are produced by heavy ion irradiation followed by chemical etching of the ion tracks. The irradiation parameters determine the porosity (areal density of the capillaries) and angular spread, while the channel diameters and shapes depend on the chemical process parameters. Such polycarbonate (and other materials) membranes are commercially available from a few manufacturers. The primary use of the filters involves packaging and filtering applications. Moreover, they are used for collecting atmospheric aerosols for environmental research. The nanocapillaries formed in membranes are particularly suitable for ion and electron guiding studies of a recently discovered, but not yet completely understood capillary guiding phenomenon. This interesting guiding effect is very promising for patterning by parallel writing with ions and/or electrons through masks. In order to get a better understanding of this phenomenon, we need a better characterization of the capillaries themselves. This study is addressing the angular distribution of the nanochannels in the polycarbonate filters by using a nuclear microprobe facility and the method of scanning transmission ion microscopy (STIM). The STIM experiments in this work have been performed at ATOMKI. The proton energy was 2 MeV, the beam intensity was about 1000 protons s-1, the beam spot size was about 1 x 1 μm, the scan size was 100 x 100 μm and the beam divergence was smaller than 0.07 deg. A scanning electron microscope (SEM, Hitachi S4300 CFE) was used to measure the capillary diameters and the membrane porosity. The sample thickness was determined by a profilometer (AMBIOS XP-I). We have investigated two different pieces of Millipore IsoporeTM samples. A typical SEM image showed several overlapping holes

  20. Transcranial phase aberration correction using beam simulations and MR-ARFI

    Purpose: Transcranial magnetic resonance-guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation-MR-ARFI technique to achieve aberration correction for transcranial MR-guided focused ultrasound surgery. The technique uses ultrasound beam propagation simulations with MR Acoustic Radiation Force Imaging (MR-ARFI) to correct skull-caused phase aberrations. Methods: Skull-based numerical aberrations were obtained from a MR-guided focused ultrasound patient treatment and were added to all elements of the InSightec conformal bone focused ultrasound surgery transducer during transmission. In the first experiment, the 1024 aberrations derived from a human skull were condensed into 16 aberrations by averaging over the transducer area of 64 elements. In the second experiment, all 1024 aberrations were applied to the transducer. The aberrated MR-ARFI images were used in the hybrid simulation-MR-ARFI technique to find 16 estimated aberrations. These estimated aberrations were subtracted from the original aberrations to result in the corrected images. Each aberration experiment (16-aberration and 1024-aberration) was repeated three times. Results: The corrected MR-ARFI image was compared to the aberrated image and the ideal image (image with zero aberrations) for each experiment. The hybrid simulation-MR-ARFI technique resulted in an average increase in focal MR-ARFI phase of 44% for the 16-aberration case and 52% for the 1024-aberration case, and recovered 83% and 39% of the ideal MR-ARFI phase for the 16-aberrations and 1024-aberration case, respectively. Conclusions: Using one MR-ARFI image and noa priori information about the applied phase aberrations, the hybrid simulation-MR-ARFI technique improved the maximum MR-ARFI phase of the beam's focus

  1. Transcranial phase aberration correction using beam simulations and MR-ARFI

    Vyas, Urvi, E-mail: urvi.vyas@gmail.com; Kaye, Elena; Pauly, Kim Butts [Department of Radiology, Stanford University, Stanford, California 94305 (United States)

    2014-03-15

    Purpose: Transcranial magnetic resonance-guided focused ultrasound surgery is a noninvasive technique for causing selective tissue necrosis. Variations in density, thickness, and shape of the skull cause aberrations in the location and shape of the focal zone. In this paper, the authors propose a hybrid simulation-MR-ARFI technique to achieve aberration correction for transcranial MR-guided focused ultrasound surgery. The technique uses ultrasound beam propagation simulations with MR Acoustic Radiation Force Imaging (MR-ARFI) to correct skull-caused phase aberrations. Methods: Skull-based numerical aberrations were obtained from a MR-guided focused ultrasound patient treatment and were added to all elements of the InSightec conformal bone focused ultrasound surgery transducer during transmission. In the first experiment, the 1024 aberrations derived from a human skull were condensed into 16 aberrations by averaging over the transducer area of 64 elements. In the second experiment, all 1024 aberrations were applied to the transducer. The aberrated MR-ARFI images were used in the hybrid simulation-MR-ARFI technique to find 16 estimated aberrations. These estimated aberrations were subtracted from the original aberrations to result in the corrected images. Each aberration experiment (16-aberration and 1024-aberration) was repeated three times. Results: The corrected MR-ARFI image was compared to the aberrated image and the ideal image (image with zero aberrations) for each experiment. The hybrid simulation-MR-ARFI technique resulted in an average increase in focal MR-ARFI phase of 44% for the 16-aberration case and 52% for the 1024-aberration case, and recovered 83% and 39% of the ideal MR-ARFI phase for the 16-aberrations and 1024-aberration case, respectively. Conclusions: Using one MR-ARFI image and noa priori information about the applied phase aberrations, the hybrid simulation-MR-ARFI technique improved the maximum MR-ARFI phase of the beam's focus.

  2. Depth-resolution imaging of crystalline nanoclusters attached on and embedded in amorphous films using aberration-corrected TEM

    Yamasaki, Jun, E-mail: yamasaki@uhvem.osaka-u.ac.jp [Research Center for Ultra-High Voltage Electron Microscopy, Osaka University, 7-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Mori, Masayuki [Graduate School of Engineering, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan); Hirata, Akihiko [Advanced Institute for Materials Research, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Hirotsu, Yoshihiko [Institute of Scientific and Industrial Research, Osaka University, 8-1 Mihogaoka, Ibaraki, Osaka 567-0047 (Japan); Tanaka, Nobuo [EcoTopia Science Institute, Nagoya University, Furo-cho, Chikusa-ku, Nagoya 464-8603 (Japan)

    2015-04-15

    For observations of crystalline nanoclusters, the features and capabilities of depth-resolution imaging by aberration-corrected transmission electron microscopy (TEM) were investigated using image simulations and experiments for two types of samples. The first sample was gold clusters attached on an amorphous carbon film. The experimental through-focal series indicated that the focal plane for the cluster was shifted 3 nm from that for the supporting film. This difference is due to the depth-resolution imaging of the cluster and film, the mid-planes of which are separated by 3 nm along the depth direction (the electron incident direction). On the basis of this information, the three-dimensional configuration of the sample, such as the film thickness of 2 nm, was successfully illustrated. The second sample was a Zr{sub 66.7}Ni{sub 33.3} metallic glass including a medium-range-order (MRO) structure, which was approximately considered to be a crystalline cluster with a diameter of 1.6 nm. In the experimental through-focal series, the lattice fringe of the MRO cluster was visible at limited focal conditions. Image simulations reproduced well the focal conditions and also indicated a structural condition for the visualization that the embedded cluster must be apart from the mid-plane of the matrix film. Similar to the case of the first sample, this result can be explained by the idea that the “effective focal planes” for the film and cluster are at different heights. This type of depth-resolution phase contrast imaging is possible only in aberration-corrected TEM and when the sample has a simple structure and is sufficiently thin for the kinematical scattering approximation. - Highlights: • Depth-resolution imaging by aberration-corrected TEM was demonstrated. • Thickness of a carbon film supporting gold nano-crystals was successfully estimated. • A crystalline nanocluster embedded in an amorphous matrix was successfully observed. • It was clarified that

  3. Depth-resolution imaging of crystalline nanoclusters attached on and embedded in amorphous films using aberration-corrected TEM

    For observations of crystalline nanoclusters, the features and capabilities of depth-resolution imaging by aberration-corrected transmission electron microscopy (TEM) were investigated using image simulations and experiments for two types of samples. The first sample was gold clusters attached on an amorphous carbon film. The experimental through-focal series indicated that the focal plane for the cluster was shifted 3 nm from that for the supporting film. This difference is due to the depth-resolution imaging of the cluster and film, the mid-planes of which are separated by 3 nm along the depth direction (the electron incident direction). On the basis of this information, the three-dimensional configuration of the sample, such as the film thickness of 2 nm, was successfully illustrated. The second sample was a Zr66.7Ni33.3 metallic glass including a medium-range-order (MRO) structure, which was approximately considered to be a crystalline cluster with a diameter of 1.6 nm. In the experimental through-focal series, the lattice fringe of the MRO cluster was visible at limited focal conditions. Image simulations reproduced well the focal conditions and also indicated a structural condition for the visualization that the embedded cluster must be apart from the mid-plane of the matrix film. Similar to the case of the first sample, this result can be explained by the idea that the “effective focal planes” for the film and cluster are at different heights. This type of depth-resolution phase contrast imaging is possible only in aberration-corrected TEM and when the sample has a simple structure and is sufficiently thin for the kinematical scattering approximation. - Highlights: • Depth-resolution imaging by aberration-corrected TEM was demonstrated. • Thickness of a carbon film supporting gold nano-crystals was successfully estimated. • A crystalline nanocluster embedded in an amorphous matrix was successfully observed. • It was clarified that only clusters

  4. Imaging individual lanthanum atoms in zeolite Y by scanning transmission electron microscopy: evidence of lanthanum pair sites

    Xu, Pinghong; Lu, Jing; Aydin, C.; Debefve, Louise M.; Browning, Nigel D.; Chen, Cong-Yan; Gates, Bruce C.

    2015-09-01

    Images of La-exchanged NaY zeolite obtained with aberration-corrected scanning transmission electron microscopy (STEM) show that about 80% of the La cations were present as site-isolated species, with the remainder in pair sites. The distance between La cations in the pair sites ranged from 1.44 to 3.84 Å, consistent with the presence of pairs of cations tilted at various angles with respect to the support surface. The actual distance between La cations in the pair sites is inferred to be approximately 3.84 Å, which is shorter than the distance between the nearest Al sites in the zeolite (4.31 Å). The results therefore suggest the presence of dimeric structures of La cations bridged with OH groups, and the presence of such species has been inferred previously on the basis of X-ray photoelectron spectroscopy (W. Grünert, U. Sauerlandt, R. Schlögl, H.G. Karge, J. Phys. Chem., 97 (1993) 1413).

  5. Scanning transmission low energy electron microscopy

    Müllerová, Ilona; Hovorka, Miloš; Frank, Luděk

    New York : IBM T.J. Watson Research Center, 2010. s. 25. [LEEM/PEEM /7./. 08.08.2010-13.08.2010, New York] R&D Projects: GA AV ČR IAA100650902 Institutional research plan: CEZ:AV0Z20650511 Keywords : scanning electron microscope * he low energy electron microscope * graphene Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  6. In-situ aberration correction of Bessel beams using spatial light modulator

    Jákl, Petr; Arzola, A. V.; Zemánek, Pavel

    Bellingham: SPIE, 2014, 94420G: 1-5. ISBN 9781628415575. ISSN 0277-786X. [Optics and Measurement Conference 2014 (OaM 2014). Liberec (CZ), 07.10.2014-10.10.2014] R&D Projects: GA MŠk LH12018; GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : optical aberration correction * holography * spatial light modulator * optical trapping Subject RIV: BH - Optics, Masers, Lasers

  7. Nanochannel alignment analysis by scanning transmission ion microscopy

    Rajta, I.; Gál, G.A.B.; Szilasi, S.Z.;

    2010-01-01

    In this paper a study on the ion transmission ratio of a nanoporous alumina sample is presented. The sample was investigated by scanning transmission ion microscopy (STIM) with different beam sizes. The hexagonally close-packed AlO nanocapillary array, realized as a suspended membrane of 15 νm...

  8. Scanning Transmission X-Ray, Laser Scanning, and Transmission Electron Microscopy Mapping of the Exopolymeric Matrix of Microbial Biofilms

    Lawrence, J R; Swerhone, G. D. W.; Leppard, G. G.; Araki, T; Zhang, X.; West, M. M.; Hitchcock, A. P.

    2003-01-01

    Confocal laser scanning microscopy (CLSM), transmission electron microscopy (TEM), and soft X-ray scanning transmission X-ray microscopy (STXM) were used to map the distribution of macromolecular subcomponents (e.g., polysaccharides, proteins, lipids, and nucleic acids) of biofilm cells and matrix. The biofilms were developed from river water supplemented with methanol, and although they comprised a complex microbial community, the biofilms were dominated by heterotrophic bacteria. TEM provid...

  9. Derivative Form of Off-axis Aberration Correction Surface and Its Application in Solar Energy Concentration

    LI Li; CHEN Ying-Tian; HU Sen

    2009-01-01

    By using the derivative method, we obtained the same result with that of the previous work of Chen et al.in 2006.Different from the integral form, the derivative form of the surface expression published in this paper is derived from differential equation and based on the theory of non-imaging focusing heliostat proposed by Chen et al.in 2001.The comparison of the derivative form of fixed aberration correction surface has been made with that of integral form surface as well as that of spherical surface in concentrating the solar ray.

  10. Conformal optical design with combination of static and dynamic aberration corrections

    Li Yan; Li Lin; Huang Yi-Fan; Liu Jia-Guo

    2009-01-01

    Conformal domes that are shaped to meet aerodynamic requirements can increase range and speed for the host platform. Because these domes typically deviate greatly from spherical surface descriptions, a variety of aberrations are induced which vary with the field-of-regard (FOR) angle. A system for correcting optical aberrations created by a conformal dome has an outer surface and an inner surface. Optimizing the inner surface is regard as static aberration correction. A deformable mirror is placed at the position of the secondary mirror in the two-mirror all reflective imaging system, which is the dynamic aberration correction. An ellipsoidal MgF2 conformal dome with a fineness ratio of 1.0 is designed as an example. The FOR angle is 00°-30°, and the design wavelength is 4 μm. After the optimization at 7zoom positions by using the design tools Code V, the root-mean-square (RMS) spot size is reduced to approximately 0.99 to 1.48 times the diffraction limit. The design results show that the performances of the conformal optical systems can be greatly improved by the combination of the static correction and the dynamic correction.

  11. Correlation of structure and mass via scanning transmission electron microscopy

    Tacke, S.; Krzyžánek, Vladislav; Reichelt, R.; Klingauf, J.

    Vol. 2. Regensburg: University of Regensburg, 2013, s. 310-311. [Microscopy Conference 2013. Regensburg (DE), 25.08.2013-30. 08.2013] R&D Projects: GA MŠk EE.2.3.20.0103 Institutional support: RVO:68081731 Keywords : quantitative scanning transmission electron microscopy * mass measurement Subject RIV: BH - Optics, Masers, Lasers

  12. Development of a compact scanning transmission X-Ray microscope

    We report a compact scanning transmission X-ray microscope newly designed and developed at the Photon Factory. The microscope has very compact size and is equipped with fully digitized control electronics to realize high stability, precise positioning and fast data acquisition. The hardware design of the microscope is described in detail. Results of measurement using test samples are also presented.

  13. Novel approach to stationary transmission scanning using Compton scattered radiation

    Transmission scanning-based estimation of the attenuation map plays a crucial role in quantitative radionuclide imaging. X-ray computed tomography (CT) reconstructs directly the attenuation coefficients map from data transmitted through the object. This paper proposes an alternative route for reconstructing the object attenuation map by exploiting Compton scatter of transmitted radiation from an externally placed radionuclide source. In contrast to conventional procedures, data acquisition is realized as a series of images parameterized by the Compton scattering angle and registered on a stationary gamma camera operating without spatial displacement. Numerical simulation results using realistic voxel-based phantoms are presented to illustrate the efficiency of this new transmission scanning approach for attenuation map reconstruction. The encouraging results presented in this paper may suggest the possibility of proposing a new concept for emission/transmission imaging using scattered radiation, which has many advantages compared to conventional technologies

  14. Simultaneous emission and transmission scanning in positron emission tomography

    Examination by PET (positron emission tomography) scanning, following the dosage of 2-deoxy-18F fluoro-D-glucose (FDG), is positively utilized for the diagnosis of cancers, rather than for the purpose of studies. This is because the examination by FDG-PET (PET scanning following the dosage of FDG) ensures higher efficiency in discrimination of cancers, than conventional CT and PET. The method of whole body scanning by PET scanning following the dosage of FDG is effectively utilized not only for discrimination cancers, but also for determining the degree of malignancy of tumors and evaluating the methods of treatment of cancers. In conventional methods for examining the degree of malignancy of tumors and evaluating the methods of cancer treatment, it is necessary to correct for the gamma-ray attenuation, which requires a longer time for examination, increasing the physical and psychological pains of the patients. We have installed the simultaneous emission and transmission scanning capability into the HEADTOME-V of the Shimadzu SET-2000W Series positron emission tomographic scanning instruments, to establish an instrument that permits FDG-PET whole body scanning in actual clinical fields, with minimized physical and psychological pains of patients concerned, yet ensuring an outstandingly high examination efficiency. This report also presents some data obtained by this newly developed instrument and those obtained in practical applications. (author)

  15. Adaptive, spatially-varying aberration correction for real-time holographic projectors.

    Kaczorowski, Andrzej; Gordon, George S D; Wilkinson, Timothy D

    2016-07-11

    A method of generating an aberration- and distortion-free wide-angle holographically projected image in real time is presented. The target projector is first calibrated using an automated adaptive-optical mechanism. The calibration parameters are then fed into the hologram generation program, which applies a novel piece-wise aberration correction algorithm. The method is found to offer hologram generation times up to three orders of magnitude faster than the standard method. A projection of an aberration- and distortion-free image with a field of view of 90x45 degrees is demonstrated. The implementation on a mid-range GPU achieves high resolution at a frame rate up to 12fps. The presented methods are automated and can be performed on any holographic projector. PMID:27410846

  16. Progress on PEEM3 - An Aberration Corrected X-Ray Photoemission Electron Microscope at the ALS

    A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment of a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase

  17. Progress on PEEM3 -- An Aberration Corrected X-Ray Photoemission Electron Microscope at the ALS

    A new ultrahigh-resolution photoemission electron microscope called PEEM3 is being developed and built at the Advanced Light Source (ALS). An electron mirror combined with a much-simplified magnetic dipole separator is to be used to provide simultaneous correction of spherical and chromatic aberrations. It is installed on an elliptically polarized undulator (EPU) beamline, and will be operated with very high spatial resolution and high flux to study the composition, structure, electric and magnetic properties of complex materials. The instrument has been designed and is described. The instrumental hardware is being deployed in 2 phases. The first phase is the deployment of a standard PEEM type microscope consisting of the standard linear array of electrostatic electron lenses. The second phase will be the installation of the aberration corrected upgrade to improve resolution and throughput. This paper describes progress as the instrument enters the commissioning part of the first phase

  18. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy

    Levin, Barnaby D.A.; Padgett, Elliot; Chen, Chien-Chun; Scott, M C; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruña, Hector D.; Richard D Robinson

    2016-01-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the cu...

  19. Optical transmission scanning for damage quantification in impacted GFRP composites

    Khomenko, Anton; Karpenko, Oleksii; Koricho, Ermias G.; Haq, Mahmoodul; Cloud, Gary L.; Udpa, Lalita

    2016-04-01

    Glass fiber reinforced polymer (GFRP) composites constitute nearly 90% of the global composites market and are extensively used in aerospace, marine, automotive and construction industries. While their advantages of lightweight and superior mechanical properties are well explored, non-destructive evaluation (NDE) techniques that allow for damage/defect detection and assessment of its extent and severity are not fully developed. Some of the conventional NDE techniques for GFRPs include ultrasonics, X-ray, IR thermography, and a variety of optical techniques. Optical methods, specifically measuring the transmission properties (e.g. ballistic optical imaging) of specimens, provide noninvasive, safe, inexpensive, and compact solutions and are commonly used in biomedical applications. In this work, this technique is adapted for rapid NDE of GFRP composites. In its basic form, the system for optical transmission scanning (OTS) consists of a light source (laser diode), a photo detector and a 2D translation stage. The proposed technique provides high-resolution, rapid and non-contact OT (optical transmittance)-scans, and does not require any coupling. The OTS system was used for inspection of pristine and low-velocity impacted (damaged) GFRP samples. The OT-scans were compared with conventional ultrasonic C-scans and showed excellent agreement but with better resolution. Overall, the work presented lays the groundwork for cost-effective, non-contact, and rapid NDE of GFRP composite structures.

  20. Attenuation correction without transmission scan for the MAMMI breast PET

    Whole-body Positron Emission Tomography (PET) scanners are required in order to span large Fields of View (FOV). Therefore, reaching the sensitivity and spatial resolution required for early stage breast tumor detection is not straightforward. MAMMI is a dedicated breast PET scanner with a ring geometry designed to provide PET images with a spatial resolution as high as 1.5 mm, being able to detect small breast tumors (<1cm). The patient lays down in prone position during the scan, thus making possible to image the whole breast, up to regions close to the base of the pectoral without the requirement of breast compression. Attenuation correction (AC) for PET data improves the image quality and the quantitative accuracy of radioactivity distribution determination. In dedicated, high resolution breast cancer scanners, this correction would enhance the proper diagnosis in early disease stages. In whole-body PET scanners, AC is usually taken into account with the use of transmission scans, either by external radioactive rod sources or by Computed Tomography (CT). This considerably increases the radiation dose administered to the patient and time needed for the exploration. In this work we propose a method for breast shape identification by means of PET image segmentation. The breast shape identification will be used for the determination of the AC. For the case of a specific breast PET scanner the procedure we propose should provide AC similar to that obtained by transmission scans as we take advantage of the breast anatomical simplicity. Experimental validation of the proposed approach with a dedicated breast PET prototype is also presented. The main advantage of this method is an important dose reduction since the transmission scan is not required.

  1. Nanostructural and Chemical Characterization of Supported Metal Oxide Catalysts by Aberration Corrected Analytical Electron Microscopy

    Zhou, Wu

    In this thesis, aberration corrected STEM imaging and chemical analysis techniques have been extensively applied in the structural and chemical characterization of supported tungsten oxide catalysts in an attempt to reveal the structure-activity relationships at play in these catalyst systems. The supported WO3/ZrO2 solid acid catalyst system is a major focal point of this thesis, and detailed aberration-corrected STEM-HAADF imaging studies were performed on a systematic set of catalysts showing different level of catalytic performance. The nature of the catalytically most active WOx species was identified by correlating structural information, obtained from STEM-HAADF and in-situ optical spectroscopy studies, with catalytic testing results. Specifically, ˜1nm distorted Zr-WOx mixed oxide clusters were identified to be the most active species for both the methanol dehydration and n-pentane isomerization reactions in the WO3/ZrO2 catalyst system. The use of amorphous zirconia as a precursor support material makes it much easier to extract and incorporate Zr cations into the surface WOx clusters during calcination. The calcination temperature was also identified to also play an important role in the formation of these most active Zr-WOx clusters. When the calcination temperature is comparable to or higher than the 896K Huttig temperature of ZrO2 (at which surface ZrO x species have sufficient mobility to agglomerate and sinter), the chance for successful surface WOx and ZrOx intermixing is significantly increased. Based on this perceived structure-activity relationship, several new catalyst synthesis strategies were developed in an attempt to optimize the catalytic performance of WOx-based catalysts. We have demonstrated in Chapter 3 that co-impregnation of WOx and ZrOx precursors onto an inactive model WO3/ZrO2 catalyst, followed by a calcination treatment above the 896K Huttig temperature of ZrO 2, promotes the surface diffusion of ZrO2 and intermixing of Zr

  2. A monochromatic, aberration-corrected, dual-beam low energy electron microscope

    The monochromatic, aberration-corrected, dual-beam low energy electron microscope (MAD-LEEM) is a novel instrument aimed at imaging of nanostructures and surfaces at sub-nanometer resolution that includes a monochromator, aberration corrector and dual beam illumination. The monochromator reduces the energy spread of the illuminating electron beam, which significantly improves spectroscopic and spatial resolution. The aberration corrector utilizes an electron mirror with negative aberrations that can be used to compensate the aberrations of the LEEM objective lens for a range of electron energies. Dual flood illumination eliminates charging generated when a conventional LEEM is used to image insulating specimens. MAD-LEEM is designed for the purpose of imaging biological and insulating specimens, which are difficult to image with conventional LEEM, Low-Voltage SEM, and TEM instruments. The MAD-LEEM instrument can also be used as a general purpose LEEM with significantly improved resolution. The low impact energy of the electrons is critical for avoiding beam damage, as high energy electrons with keV kinetic energies used in SEMs and TEMs cause irreversible change to many specimens, in particular biological materials. A potential application for MAD-LEEM is in DNA sequencing, which demands imaging techniques that enable DNA sequencing at high resolution and speed, and at low cost. The key advantages of the MAD-LEEM approach for this application are the low electron impact energies, the long read lengths, and the absence of heavy-atom DNA labeling. Image contrast simulations of the detectability of individual nucleotides in a DNA strand have been developed in order to refine the optics blur and DNA base contrast requirements for this application. - Highlights: • We present a LEEM with a monochromator, aberration corrector, and two electron beams. • We analyze objective lens aberrations up to 5th order with aberration correction. • Tetrode and pentode mirror

  3. A computer program for scanning transmission ion microscopy simulation

    Wu, R.; Shen, H.; Mi, Y.; Sun, M. D.; Yang, M. J.

    2005-04-01

    With the installation of the Scanning Proton Microprobe system at Fudan University, we are in the process of developing a three-dimension reconstruction technique based on scanning transmission ion microscopy-computed tomography (STIM-CT). As the first step, a related computer program of STIM simulation has been established. This program is written in the Visual C++®, using the technique of OOP (Object Oriented Programming) and it is a standard multiple-document Windows® program. It can be run with all MS Windows® operating systems. The operating mode is the menu mode, using a multiple process technique. The stopping power theory is based on the Bethe-Bloch formula. In order to simplify the calculation, the improved cylindrical coordinate model was introduced in the program instead of a usual spherical or cylindrical coordinate model. The simulated results of a sample at several rotation angles are presented.

  4. Transmission through thin films by low energy scanning electron microscopy

    Müllerová, Ilona; Hovorka, Miloš; Sobota, Jaroslav; Hanzlíková, Renáta; Fořt, Tomáš; Frank, Luděk

    Graz : Verlag der Technischen Universität, 2009, Vol. 1: 163-164. ISBN 978-3-85125-062-6. [MC 2009 - Joint Meeting of Dreiländertagung and Multinational Congress on Microscopy /9./. Graz (AT), 30.08.2009-04.09.2009] R&D Projects: GA AV ČR IAA100650902 Institutional research plan: CEZ:AV0Z20650511 Keywords : low energy electrons * thin fílms * scanning transmission elektron microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering http://www.univie.ac.at/asem/Graz_MC_09/papers/95398.pdf

  5. Free-standing graphene by scanning transmission electron microscopy

    Free-standing graphene sheets have been imaged by scanning transmission electron microscopy (STEM). We show that the discrete numbers of graphene layers enable an accurate calibration of STEM intensity to be performed over an extended thickness and with single atomic layer sensitivity. We have applied this calibration to carbon nanoparticles with complex structures. This leads to the direct and accurate measurement of the electron mean free path. Here, we demonstrate potentials using graphene sheets as a novel mass standard in STEM-based mass spectrometry.

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

    Yoshida, K.; Shiju, N. R.; Brown, D. R.; Boyes, E. D.; Gai, P. L.

    2010-07-01

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

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

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

  8. A Bloch wave analysis of optical sectioning in aberration-corrected STEM

    The reduction in the focal depth of field that occurs through the use of larger apertures in aberration-corrected STEM allows three-dimensional information to be retrieved by optical depth sectioning. This paper explores depth sectioning in zone-axis crystals using Bloch wave calculations. By decomposing the calculation into the contribution from individual states and from individual partial plane waves in the convergent cone of illumination, we explain the form of the electron intensity in the crystal as a function of depth. Two separate effects are found that can cause the intensity maximum to deviate from that of the expected defocus value. Firstly it is found that the unbound, high angle excited states give rise to a behaviour similar to that of the probe focusing in the vacuum, but with a prefocusing effect due to the lensing effect of the potential of the atomic column. Superimposed upon this prefocused peak is an oscillation due to interference between the channelling 1s state and the rest of the wavefunction. This oscillation can actually prevent an intensity maximum being formed at certain depths in the crystal, and will complicate the interpretation of optical sectioning data

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

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

    2010-07-01

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

  10. A broadband toolbox for scanning microwave microscopy transmission measurements

    Lucibello, Andrea; Sardi, Giovanni Maria; Capoccia, Giovanni; Proietti, Emanuela; Marcelli, Romolo; Kasper, Manuel; Gramse, Georg; Kienberger, Ferry

    2016-05-01

    In this paper, we present in detail the design, both electromagnetic and mechanical, the fabrication, and the test of the first prototype of a Scanning Microwave Microscope (SMM) suitable for a two-port transmission measurement, recording, and processing the high frequency transmission scattering parameter S21 passing through the investigated sample. The S21 toolbox is composed by a microwave emitter, placed below the sample, which excites an electromagnetic wave passing through the sample under test, and is collected by the cantilever used as the detector, electrically matched for high frequency measurements. This prototype enhances the actual capability of the instrument for a sub-surface imaging at the nanoscale. Moreover, it allows the study of the electromagnetic properties of the material under test obtained through the measurement of the reflection (S11) and transmission (S21) parameters at the same time. The SMM operates between 1 GHz and 20 GHz, current limit for the microwave matching of the cantilever, and the high frequency signal is recorded by means of a two-port Vector Network Analyzer, using both contact and no-contact modes of operation, the latter, especially minded for a fully nondestructive and topography-free characterization. This tool is an upgrade of the already established setup for the reflection mode S11 measurement. Actually, the proposed setup is able to give richer information in terms of scattering parameters, including amplitude and phase measurements, by means of the two-port arrangement.

  11. Imaging screw dislocations at atomic resolution by aberration-corrected electron optical sectioning

    Yang, H.; Lozano, J. G.; Pennycook, T. J.; Jones, L.; Hirsch, P. B.; Nellist, P. D.

    2015-06-01

    Screw dislocations play an important role in materials' mechanical, electrical and optical properties. However, imaging the atomic displacements in screw dislocations remains challenging. Although advanced electron microscopy techniques have allowed atomic-scale characterization of edge dislocations from the conventional end-on view, for screw dislocations, the atoms are predominantly displaced parallel to the dislocation line, and therefore the screw displacements are parallel to the electron beam and become invisible when viewed end-on. Here we show that screw displacements can be imaged directly with the dislocation lying in a plane transverse to the electron beam by optical sectioning using annular dark field imaging in a scanning transmission electron microscope. Applying this technique to a mixed [a+c] dislocation in GaN allows direct imaging of a screw dissociation with a 1.65-nm dissociation distance, thereby demonstrating a new method for characterizing dislocation core structures.

  12. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    Tromp, R.M., E-mail: rtromp@us.ibm.com [IBM T.J. Watson Research Center, 1101 Kitchawan Road, Yorktown Heights, NY 10598 (United States); Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands); Schramm, S.M. [Leiden Institute of Physics, Kamerlingh Onnes Laboratory, Niels Bohrweg 2, 2333 CA Leiden (Netherlands)

    2013-02-15

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C{sub 3}-corrected microscopes it is well established that a small negative value of C{sub 3}, offset by positive values of C{sub 5} and defocus C{sub 1} results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C{sub 1} and C{sub 3}. We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed.

  13. Optimization and stability of the contrast transfer function in aberration-corrected electron microscopy

    The Contrast Transfer Function (CTF) describes the manner in which the electron microscope modifies the object exit wave function as a result of objective lens aberrations. For optimum resolution in C3-corrected microscopes it is well established that a small negative value of C3, offset by positive values of C5 and defocus C1 results in the most optimal instrument resolution, and optimization of the CTF has been the subject of several studies. Here we describe a simple design procedure for the CTF that results in a most even transfer of information below the resolution limit. We address not only the resolution of the instrument, but also the stability of the CTF in the presence of small disturbances in C1 and C3. We show that resolution can be traded for stability in a rational and transparent fashion. These topics are discussed quantitatively for both weak-phase and strong-phase (or amplitude) objects. The results apply equally to instruments at high electron energy (TEM) and at very low electron energy (LEEM), as the basic optical properties of the imaging lenses are essentially identical. - Highlights: ► An optimized Contrast Transfer Function for aberration corrected electron microscopes is proposed. ► Based on the properties of the CTF near optimum settings, we address its stability. ► Over some range of parameters resolution can be traded for stability. ► These issues are addressed for weak-phase objects, as well as strong-phase and amplitude object. ► We compare our results with CTF settings previously proposed

  14. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy

    Levin, Barnaby D A; Chen, Chien-Chun; Scott, M C; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruna, Hector D; Robinson, Richard D; Ercius, Peter; Kourkoutis, Lena F; Miao, Jianwei; Muller, David A; Hovden, Robert

    2016-01-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180{\\deg} tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of p...

  15. High order aberration and straylight evaluation after cataract surgery with implantation of an aspheric,aberration correcting monofocal intraocular lens

    Florian; T; A; Kretz; Tamer; Tandogan; Ramin; Khoramnia; Gerd; U; Auffarth

    2015-01-01

    ·AIM: To evaluate the quality of vision in respect to high order aberrations and straylight perception after implantation of an aspheric, aberration correcting,monofocal intraocular lens(IOL).·METHODS: Twenty-one patients(34 eyes) aged 50 to83 y underwent cataract surgery with implantation of an aspheric, aberration correcting IOL(Tecnis ZCB00,Abbott Medical Optics). Three months after surgery they were examined for uncorrected(UDVA) and corrected distance visual acuity(CDVA), contrast sensitivity(CS)under photopic and mesopic conditions with and without glare source, ocular high order aberrations(HOA, Zywave II) and retinal straylight(C-Quant).· RESULTS: Postoperatively, patients achieved a postoperative CDVA of 0.0 log MAR or better in 97.1% of eyes. Mean values of high order abberations were +0.02±0.27(primary coma components) and-0.04 ±0.16(spherical aberration term). Straylight values of the C-Quant were 1.35±0.44 log which is within normal range of age matched phakic patients. The CS measurements under mesopic and photopic conditions in combination with and without glare did not show any statistical significance in the patient group observed(P ≥0.28).· CONCLUSION: The implantation of an aspherical aberration correcting monofocal IOL after cataractsurgery resulted in very low residual higher order aberration(HOA) and normal straylight.

  16. Influence of single-photon-transmission scan duration measured with the ECAT ART PET-scanner

    Aim: The aim was to study the influence of single-photon-transmission scan duration in 3D-PET on the quantitative values of attenuation coefficients and noise in transmission images and of activity concentrations and noise in attenuation corrected emission images of thorax phantom- and patient data. Method and material: Using dual collimated Cs-137 singles transmission sources (Eγ = 662 keV, A = 2* 614 MBq) on an ECAT ART tomography series of transmission scans of a thorax phantom were acquired pre- and post-injection of 18F. 17 patients underwent two transmission scans. The scan time of the short transmission was chosen according to the results of the phantom studies (noise of Poisson statistics less than 4%). Transmission and attenuation corrected emission images were evaluated with respect to estimated linear attenuation coefficients, noise and specific activities in organs. Results: The phantom studies reveal little variation of the estimated linear attenuation coefficients as a function of scan duration. The estimates of the attenuation coefficients are found to be 1% lower than the expected values for pre- and up to 6.5% lower for post-injection transmissions. The noise level in the transmission images increases as expected for Poisson data. The noise level in the attenuation corrected emission images shows only little increase with decreasing transmission scan time whereas it is strongly influenced by a variation of emission scan time. In patient studies, less than 3% difference was found in the estimated linear attenuation coefficients as well as in the activity concentrations between short (pre or post-injection) and long transmission scans. The noise levels in transmission and emission images are 1% (pre-injection) and 4% (post-injection) higher for short transmission scans. Conclusion: Due to the high photon flux, single photon transmission offers good clinical performance with significantly reduced transmission scan durations (<2 min/bed in pre-, <4

  17. Image formation mechanisms of spherical aberration corrected BF STEM imaging methods

    In this study, we explore the formation mechanisms of different spherical-aberration (Cs)-corrected bright-field (BF) scanning transmission electron microscope (STEM) imaging methods. The Cs-corrected BF STEM imaging modes are characterised in detail using simulated images and experimental BF STEM images obtained with several types of detectors. The Co3O4 specimen results show that the occupancy, the atomic spacing, and the atomic number of the atoms constituting the atomic columns control image formation in BF STEM imaging, which is used to detect light atomic columns. The middle-angle BF STEM image is crucial in image formation by BF STEM imaging. - Highlights: • We explore the formation mechanisms of diversified Cs-corrected STEM imaging methods. • SrTiO3 and Co3O4 were observed by several BF STEM imaging methods. • MABF STEM plays a key role in image formation for visualising a light atomic column. • Occupancy, spacing and the atomic number in atomic columns control the image formation

  18. Statistical image reconstruction methods for simultaneous emission/transmission PET scans

    Transmission scans are necessary for estimating the attenuation correction factors (ACFs) to yield quantitatively accurate PET emission images. To reduce the total scan time, post-injection transmission scans have been proposed in which one can simultaneously acquire emission and transmission data using rod sources and sinogram windowing. However, since the post-injection transmission scans are corrupted by emission coincidences, accurate correction for attenuation becomes more challenging. Conventional methods (emission subtraction) for ACF computation from post-injection scans are suboptimal and require relatively long scan times. We introduce statistical methods based on penalized-likelihood objectives to compute ACFs and then use them to reconstruct lower noise PET emission images from simultaneous transmission/emission scans. Simulations show the efficacy of the proposed methods. These methods improve image quality and SNR of the estimates as compared to conventional methods

  19. Amyloid Structure and Assembly: Insights from Scanning Transmission Electron Microscopy

    Goldsbury, C.; Wall, J.; Baxa, U.; Simon, M. N.; Steven, A. C.; Engel, A.; Aebi, U.; Muller, S. A.

    2011-01-01

    Amyloid fibrils are filamentous protein aggregates implicated in several common diseases such as Alzheimer's disease and type II diabetes. Similar structures are also the molecular principle of the infectious spongiform encephalopathies such as Creutzfeldt-Jakob disease in humans, scrapie in sheep, and of the so-called yeast prions, inherited non-chromosomal elements found in yeast and fungi. Scanning transmission electron microscopy (STEM) is often used to delineate the assembly mechanism and structural properties of amyloid aggregates. In this review we consider specifically contributions and limitations of STEM for the investigation of amyloid assembly pathways, fibril polymorphisms and structural models of amyloid fibrils. This type of microscopy provides the only method to directly measure the mass-per-length (MPL) of individual filaments. Made on both in vitro assembled and ex vivo samples, STEM mass measurements have illuminated the hierarchical relationships between amyloid fibrils and revealed that polymorphic fibrils and various globular oligomers can assemble simultaneously from a single polypeptide. The MPLs also impose strong constraints on possible packing schemes, assisting in molecular model building when combined with high-resolution methods like solid-state nuclear magnetic resonance (NMR) and electron paramagnetic resonance (EPR).

  20. Nanomaterial datasets to advance tomography in scanning transmission electron microscopy.

    Levin, Barnaby D A; Padgett, Elliot; Chen, Chien-Chun; Scott, M C; Xu, Rui; Theis, Wolfgang; Jiang, Yi; Yang, Yongsoo; Ophus, Colin; Zhang, Haitao; Ha, Don-Hyung; Wang, Deli; Yu, Yingchao; Abruña, Hector D; Robinson, Richard D; Ercius, Peter; Kourkoutis, Lena F; Miao, Jianwei; Muller, David A; Hovden, Robert

    2016-01-01

    Electron tomography in materials science has flourished with the demand to characterize nanoscale materials in three dimensions (3D). Access to experimental data is vital for developing and validating reconstruction methods that improve resolution and reduce radiation dose requirements. This work presents five high-quality scanning transmission electron microscope (STEM) tomography datasets in order to address the critical need for open access data in this field. The datasets represent the current limits of experimental technique, are of high quality, and contain materials with structural complexity. Included are tomographic series of a hyperbranched Co2P nanocrystal, platinum nanoparticles on a carbon nanofibre imaged over the complete 180° tilt range, a platinum nanoparticle and a tungsten needle both imaged at atomic resolution by equal slope tomography, and a through-focal tilt series of PtCu nanoparticles. A volumetric reconstruction from every dataset is provided for comparison and development of post-processing and visualization techniques. Researchers interested in creating novel data processing and reconstruction algorithms will now have access to state of the art experimental test data. PMID:27272459

  1. High-resolution imaging in the scanning transmission electron microscope

    The high-resolution imaging of crystalline materials in the scanning transmission electron microscopy (STEM) is reviewed with particular emphasis on the conditions under which an incoherent image can be obtained. It is shown that a high-angle annular detector can be used to break the coherence of the imaging process, in the transverse plane through the geometry of the detector, or in three dimensions if multiphonon diffuse scattering is detected. In the latter case, each atom can be treated as a highly independent source of high-angle scattering. The most effective fast electron states are therefore tightly bound s-type Bloch states. Furthermore, they add constructively for each incident angle in the coherent STEM probe, so that s states are responsible for practically the entire image contrast. Dynamical effects are largely removed, and almost perfect incoherent imaging is achieved. s states are relatively insensitive to neighboring strings, so that incoherent imaging is maintained for superlattice and interfaces, and supercell calculations are unnecessary. With an optimum probe profile, the incoherent image represents a direct image of the crystal projection, with compositional sensitivity built in through the strong dependence of the scattering cross sections on atomic number Z

  2. Scanning transmission electron microscopy: Albert Crewe's vision and beyond

    Some four decades were needed to catch up with the vision that Albert Crewe and his group had for the scanning transmission electron microscope (STEM) in the nineteen sixties and seventies: attaining 0.5 Å resolution, and identifying single atoms spectroscopically. With these goals now attained, STEM developments are turning toward new directions, such as rapid atomic resolution imaging and exploring atomic bonding and electronic properties of samples at atomic resolution. The accomplishments and the future challenges are reviewed and illustrated with practical examples. -- Highlights: ► TV-rate STEM imaging of heavy atoms is demonstrated. ► DNA sequencing by STEM dark field imaging should be possible at a rate of 106 bases/s. ► Individual silicon atom impurities in graphene are imaged atom-by-atom. ► Single atoms of nitrogen and boron incorporated in graphene are imaged spectroscopically. ► Bonding of individual atoms can be probed by analyzing the fine structures of their EEL spectra.

  3. Double-aberration corrected TEM/STEM of solid acid nanocatalysts in the development of pharmaceutical NSAIDS

    Yoshida, K.; Shiju, N.; Brown, R.; Wright, I.; Boyes, E. D.; Gai, P. L.

    2012-07-01

    We report nanostructural and physico-chemical studies in the development of an efficient low temperature heterogeneous catalytic process for nonsteroidal anti-inflammatory drugs (NSAIDS) such as N-acetyl-p-aminophenol (paracetamol or acetaminophen) on tungstated zirconia nanocatalysts. Using a double-aberration corrected TEM/STEM, modified in-house for in-situ studies at the sub-Angstrom level, we directly observed in real-time, the dynamic precursor transformation to the active catalyst. We quantified the observations with catalytic activity studies for the NSAIDS. The studies have provided the direct evidence for single tungsten promoter atoms and surface WOx species of pharmaceuticals.

  4. [Aberration corrected intraocular lens for microincision cataract surgery (MICS). Intraindividual comparison with a conventional lens - 1-year follow-up].

    Möglich, M; Häberle, H; Pham, D T; Wirbelauer, C

    2009-10-01

    Microincision cataract surgery (MICS) is an important advancement in the field of cataract surgery. This article compares an aberration corrected hydrophilic acrylic intraocular lens (IOL) having a hydrophobic surface for MICS with a one-piece hydrophobic acrylic IOL with respect to capsule sac stability, image quality, and after-cataract formation over the course of 1 year. The operations were performed as bimanual MICS or coaxial phacoemulsification. Overall the results after implantation of the IOL by MICS can be regarded as positive in comparison to the standard operation. PMID:18836727

  5. Study on the use of transmission scans for whole body PET attenuation correction

    Transmission scans for attenuation correction of whole body PET studies are not acquired routinely, since noise considerations impose acquisition time constraints that make conventional scanning techniques infeasible. The aim of this work is to optimize data acquisition and processing parameters and improve the SNR of whole body transmission scans, in order to achieve within a reasonable time frame, an attenuation correction of the same quality as in cardiac PET. Methods to improve the scanner sensitivity by using additional coincidence planes, as well as smoothing methods for the randoms and the transmission data were investigated. Phantom and patient studies show that transmission scans are feasible for whole body PET studies, with equivalent noise introduced in the chest area as in a typical cardiac PET attenuation correction, at fractions of the time required by conventional transmission scan protocols

  6. Comparison of analytical and numerical approaches for CT-based aberration correction in transcranial passive acoustic imaging

    Jones, Ryan M.; Hynynen, Kullervo

    2016-01-01

    Computed tomography (CT)-based aberration corrections are employed in transcranial ultrasound both for therapy and imaging. In this study, analytical and numerical approaches for calculating aberration corrections based on CT data were compared, with a particular focus on their application to transcranial passive imaging. Two models were investigated: a three-dimensional full-wave numerical model (Connor and Hynynen 2004 IEEE Trans. Biomed. Eng. 51 1693-706) based on the Westervelt equation, and an analytical method (Clement and Hynynen 2002 Ultrasound Med. Biol. 28 617-24) similar to that currently employed by commercial brain therapy systems. Trans-skull time delay corrections calculated from each model were applied to data acquired by a sparse hemispherical (30 cm diameter) receiver array (128 piezoceramic discs: 2.5 mm diameter, 612 kHz center frequency) passively listening through ex vivo human skullcaps (n  =  4) to emissions from a narrow-band, fixed source emitter (1 mm diameter, 516 kHz center frequency). Measurements were taken at various locations within the cranial cavity by moving the source around the field using a three-axis positioning system. Images generated through passive beamforming using CT-based skull corrections were compared with those obtained through an invasive source-based approach, as well as images formed without skull corrections, using the main lobe volume, positional shift, peak sidelobe ratio, and image signal-to-noise ratio as metrics for image quality. For each CT-based model, corrections achieved by allowing for heterogeneous skull acoustical parameters in simulation outperformed the corresponding case where homogeneous parameters were assumed. Of the CT-based methods investigated, the full-wave model provided the best imaging results at the cost of computational complexity. These results highlight the importance of accurately modeling trans-skull propagation when calculating CT-based aberration corrections

  7. Prospects for versatile phase manipulation in the TEM : beyond aberration correction

    Guzzinati, Giulio; Clark, Laura; Béché, Armand; Juchtmans, Roeland; Boxem, van, Tj.; Mazilu, Michael; Verbeeck, Jo

    2015-01-01

    Abstract: In this paper we explore the desirability of a transmission electron microscope in which the phase of the electron wave can be freely controlled. We discuss different existing methods to manipulate the phase of the electron wave and their limitations. We show how with the help of current techniques the electron wave can already be crafted into specific classes of waves each having their own peculiar properties. Assuming a versatile phase modulation device is feasible, we explore pos...

  8. Smart microscope: an adaptive optics learning system for aberration correction in multiphoton confocal microscopy.

    Albert, O; Sherman, L; Mourou, G; Norris, T B; Vdovin, G

    2000-01-01

    Off-axis aberrations in a beam-scanning multiphoton confocal microscope are corrected with a deformable mirror. The optimal mirror shape for each pixel is determined by a genetic learning algorithm, in which the second-harmonic or two-photon fluorescence signal from a reference sample is maximized. The speed of the convergence is improved by use of a Zernike polynomial basis for the deformable mirror shape. This adaptive optical correction scheme is implemented in an all-reflective system by use of extremely short (10-fs) optical pulses, and it is shown that the scanning area of an f:1 off-axis parabola can be increased by nine times with this technique. PMID:18059779

  9. Double-aberration corrected TEM/STEM of solid acid nanocatalysts in the development of pharmaceutical NSAIDS

    We report nanostructural and physico-chemical studies in the development of an efficient low temperature heterogeneous catalytic process for nonsteroidal anti-inflammatory drugs (NSAIDS) such as N-acetyl-p-aminophenol (paracetamol or acetaminophen) on tungstated zirconia nanocatalysts. Using a double-aberration corrected TEM/STEM, modified in-house for in-situ studies at the sub-Angstrom level, we directly observed in real-time, the dynamic precursor transformation to the active catalyst. We quantified the observations with catalytic activity studies for the NSAIDS. The studies have provided the direct evidence for single tungsten promoter atoms and surface WOx species of ≤ 0.35 nm, with nanoclusters of WOx (0.6 to 1nm), located at grain boundaries on the surface of the zirconia nanoparticles. The correlation between the nanostructure and catalytic activity indicates that the species create Broensted acid sites highly active for the low temperature process. The results open up opportunities for developing green heterogeneous methods for pharmaceuticals.

  10. Scanning image detection (SID) system for conventional transmission electron microscope (CTEM) images.

    Tanji, T; Tomita, M; Kobayashi, H

    1990-08-01

    A new image detection system has been developed to display transmission electron microscope (TEM) images on a CRT without a video camera system. Deflection coils placed in both the upper space of an objective lens and in the lower space of the first intermediate lens scan a small electron probe simultaneously. The electrical signal acquired through an improved scintillator and a photomultiplier is synchronized with the scanning signal and displayed in a similar fashion to a conventional scanning TEM (STEM) instrument. A preliminary system using a 100 kV conventional TEM (CTEM) equipped with a hairpin-type electron gun, produced an image with a spatial resolution of 1 nm. PMID:2391565

  11. In-situ scanning transmission X-ray microscopy of catalytic materials under reaction conditions

    de Smit, E.; Creemer, J.F.; Zandbergen, H.W.; Weckhuysen, B.M.; de Groot, F.M.F.

    2009-01-01

    In-situ Scanning X-ray Transmission Microscopy (STXM) allows the measurement of the soft X-ray absorption spectra with 10 to 30 nm spatial resolution under realistic reaction conditions. We show that STXM-XAS in combination with a micromachined nanoreactor can image a catalytic system under relevant

  12. Quantitative Phase Imaging with a Scanning Transmission X-Ray Microscope

    de Jonge, M. D.; Hornberger, B.; C. Holzner; Legnini, D.; Paterson, D.; McNulty, I.; Jacobsen, C.; Vogt, S.

    2008-01-01

    We obtain quantitative phase reconstructions from differential phase contrast images obtained with a scanning transmission x-ray microscope and 2.5 keV x rays. The theoretical basis of the technique is presented along with measurements and their interpretation.

  13. Reply to L.M. Brown et al. "Brief history of the Cambridge STEM aberration correction project and its progeny" in Ultramicroscopy 157, 88 (2015).

    Urban, K W; Rose, H

    2016-02-01

    We comment on a Short Communication recently published in Ultramicroscopy in which Brown et al. criticize our description of the time sequence of events in the development of aberration correction systems in electron optics during the 1990s put forward in the introduction to the Ultramicroscopy April 2015 Special Issue. We present an analysis of the published literature furnishing evidence that our description is correct. PMID:26624509

  14. Design and Performance Characteristics of the ORNL Advanced Microscopy Laboratory and JEOL 2200FS-AC Aberration-Corrected STEM/TEM

    Lawrence F. Allard; Douglas A. Blom; O'Keefe, Michael A.; Mishina, S.

    2005-01-01

    At ORNL, the new Advanced Microscopy Laboratory (AML) has recently been completed, with two aberration-corrected instruments installed, and two more planned in the near future to fill the 4-laboratory building. The installed JEOL 2200FS-AC has demonstrated a TEM information limit of 0.9A. This limit is expected given the measured instrument parameters (HT and OL power supply stabilities, beam energy spread, etc.), and illustrates that the environmental influences are not adversely affect...

  15. Study of Interactions Between Microbes and Minerals by Scanning Transmission X-Ray Microscopy (STXM)

    Benzerara, K.; /Paris U., VI-VII, LMCP; Tyliszczak, T.; /LBNL, ALS; Brown, G.E., Jr.; /Stanford U., Geo. Environ. Sci. /SLAC, SSRL

    2007-01-03

    Scanning Transmission X-ray Microscopy (STXM) and Transmission Electron Microscopy (TEM) were combined to characterize various samples of geomicrobiological interest down to the nanometer scale. An approach based on energy-filtered imaging was used to examine microbe-mineral interactions and the resulting biominerals, as well as biosignatures in simplified laboratory samples. This approach was then applied to natural samples, including natural biofilms entombed in calcium carbonate precipitates and bioweathered silicates and facilitated location of bacterial cells and provided unique insights about their biogeochemical interactions with minerals at the 30-40 nm scale.

  16. A dual-energy transmission detector for vehicle scanning using wavelength-shifting fibers

    Van Liew, Seth; Zhang, Ming

    2014-09-01

    A new dual energy detector for vehicle scanning is presented. The system is composed of a three-sided Compton backscatter imaging system utilizing flying-spot x-rays concurrent with a transmission detector using the same x-ray beam. This detector is under the vehicle and is thin enough to be driven over with a modest bump which does not impede vehicle trac. It uses sheet scintillator with wavelength-shifting fibers as light pipes. Results are presented on steel penetration, calibration procedures and issues, and dual energy performance. The system's dose is low enough for scanning people, including passenger vehicles.

  17. Valence electron energy-loss spectroscopy in monochromated scanning transmission electron microscopy

    With the development of monochromators for (scanning) transmission electron microscopes, valence electron energy-loss spectroscopy (VEELS) is developing into a unique technique to study the band structure and optical properties of nanoscale materials. This article discusses practical aspects of spatially resolved VEELS performed in scanning transmission mode and the alignments necessary to achieve the current optimum performance of ∼0.15 eV energy resolution with an electron probe size of ∼1 nm. In particular, a collection of basic concepts concerning the acquisition process, the optimization of the energy resolution, the spatial resolution and the data processing are provided. A brief study of planar defects in a Y1Ba2Cu3O7-δ high-temperature superconductor illustrates these concepts and shows what kind of information can be accessed by VEELS

  18. Confocal soft X-ray scanning transmission microscopy: setup, alignment procedure and limitations

    Späth, Andreas; Raabe, Jörg; Rainer H. Fink

    2015-01-01

    Zone-plate-based scanning transmission soft X-ray microspectroscopy (STXM) is a well established technique for high-contrast imaging of sufficiently transparent specimens (e.g. ultrathin biological tissues, polymer materials, archaeometric specimens or magnetic thin films) with spatial resolutions in the regime of 20 nm and high spectroscopic or chemical sensitivity. However, due to the relatively large depth of focus of zone plates, the resolution of STXM along the optical axis so far stays ...

  19. Electro-deposition of Cu studied with in situ electrochemical scanning transmission x-ray microscopy

    Hitchcock, A. P.; Qin, Z.; Rosendahl, S. M.; Lee, V.; Reynolds, M.; Hosseinkhannazer, H.

    2016-01-01

    Soft X-ray scanning transmission X-ray microscopy (STXM) was used to investigate Cu deposition onto, and stripping from a Au surface. Cu 2p spectromicroscopy was used to analyze initial and final states (ex situ processing) and follow the processes in situ. The in situ experiments were carried out using a static electrochemical cell with an electrolyte layer thickness of ˜1 μm. A new apparatus for in situ electrochemical STXM is described.

  20. In-situ scanning transmission X-ray microscopy of catalytic materials under reaction conditions

    Smit, E.; Creemer, J.F.; H.W. Zandbergen; Weckhuysen, B. M.; Groot, F.M.F. de

    2009-01-01

    In-situ Scanning X-ray Transmission Microscopy (STXM) allows the measurement of the soft X-ray absorption spectra with 10 to 30 nm spatial resolution under realistic reaction conditions. We show that STXM-XAS in combination with a micromachined nanoreactor can image a catalytic system under relevant reaction conditions, and provide detailed information on the morphology and composition of the catalyst material. The nanometer resolution combined with powerful chemical speciation by XAS and the...

  1. Advanced scanning transmission stereo electron microscopy of structural and functional engineering materials

    Agudo Jácome, L.; Eggeler, G.; Dlouhý, Antonín

    2012-01-01

    Roč. 122, NOV (2012), s. 48-59. ISSN 0304-3991 R&D Projects: GA ČR GA202/09/2073 Institutional research plan: CEZ:AV0Z20410507 Keywords : stereoscopy * scanning transmission electron microscopy * single crystal Ni-base superalloys * Dislocation substructures * Foil thickness measurement Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.470, year: 2012

  2. A scanning and transmission electron microscopic study of the membranes of chicken egg

    Tan, C K; Chen, T. W.; Chan, H L; Ng, L. S.

    1992-01-01

    Questions regarding the structure of the inner and outer shell membranes of the chicken egg were addressed in this study by correlating observations from light microscopy and scanning and transmission electron microscopy. The egg membrane had a limiting membrane, which measured .9 to .15 pn in thickness and appeared to be a continuous and an impervious layer, but the shell membrane did not. Under the SEM, each membrane was seen to be made up of severa1 fibre ...

  3. Transmission-scanning electron microscopic observations of selected Eikenella corrodens strains.

    Progulske, A; Holt, S C

    1980-01-01

    The morphology of Eikenella corrodens 333/54-55 (ATCC 23834) and two human periodontal lesion isolates, strains 470 and 373, was examined by transmission and scanning electron microscopy. All strains exhibited a cell envelope characteristic of gram-negative bacteria. Staining with ruthenium red and alcian blue revealed a loosely organized fibrous slime layer associated with the outer surface of the outer membrane. Slime "stabilization" was achieved by incubation of cells with antisera prepare...

  4. Examination Of Defect In Gas Pipeline By Gamma Transmission Scanning And Computed Tomography Techniques

    The transmission gamma scanning and computed tomography (CT) are advanced non-destructive testing techniques which can provide visual information to end-user. In recent years, industrial gamma scanning and CT equipment have been continuously improved in physical configuration and image reconstruction software have been supplemented with advanced algorithms, that can satisfy end-users with high quality computed tomography images. The first generation CT system with configuration of one source - one detector which is designed and fabricated by the Centre for Applications of Nuclear Technique in Industry (CANTI) is a dedicated equipment for examination of corrosion, erosion or blockage in petroleum pipeline. The equipment have two options of measurement: gamma transmission scanning and computed tomography scanning. The associated image reconstruction software have three image reconstruction algorithms: analytical (FBP), algebraic (ART) and statistical (EM) along with some advanced image processing techniques. CANTI had utilized the equipment to examine some fraction of gas transportation pipeline of PetroVietnam Gas Company, detected and evaluated the extent of defects, quickly providing useful information for the inspection and maintenance tasks of the client. (author)

  5. Method and apparatus for a high-resolution three dimensional confocal scanning transmission electron microscope

    de Jonge, Niels [Oak Ridge, TN

    2010-08-17

    A confocal scanning transmission electron microscope which includes an electron illumination device providing an incident electron beam propagating in a direction defining a propagation axis, and a precision specimen scanning stage positioned along the propagation axis and movable in at least one direction transverse to the propagation axis. The precision specimen scanning stage is configured for positioning a specimen relative to the incident electron beam. A projector lens receives a transmitted electron beam transmitted through at least part of the specimen and focuses this transmitted beam onto an image plane, where the transmitted beam results from the specimen being illuminated by the incident electron beam. A detection system is placed approximately in the image plane.

  6. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry.

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R; Chess, Jordan; McMorran, Benjamin J; Czarnik, Cory; Rose, Harald H; Ercius, Peter

    2016-01-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals. PMID:26923483

  7. Laser transmission welding of Clearweld-coated polyethylene glycol terephthalate by incremental scanning technique

    Wang, Y. Y.; Wang, A. H.; Weng, Z. K.; Xia, H. B.

    2016-06-01

    Transmission laser welding using Incremental Scanning Technique(TWIST) mode and conventional contour welding mode were adopted to investigate laser transmission welding of 0.5 mm thick PET plate. A 1064 nm fiber laser was used to weld PET at the (TWIST) mode, and an 808 nm diode laser was applied to conduct the conventional contour welding. The Clearweld coating was used as laser absorbing material. The influences of laser parameters (i.e. defocusing distance, distance between two circles) on the quality of weld seams were analyzed by optical microscopy. Moreover, geometry and shear strength of the weld zone were tested to optimize laser parameters. Additionally, the water vapor permeability (WVP) of weld seams was measured to test hermetical capacity. Results show that the shear strength and hermetic capacity of weld seam by TWIST mode are at the same level in comparison with that of the conventional contour welding.

  8. Efficient linear phase contrast in scanning transmission electron microscopy with matched illumination and detector interferometry

    Ophus, Colin; Ciston, Jim; Pierce, Jordan; Harvey, Tyler R.; Chess, Jordan; McMorran, Benjamin J.; Czarnik, Cory; Rose, Harald H.; Ercius, Peter

    2016-02-01

    The ability to image light elements in soft matter at atomic resolution enables unprecedented insight into the structure and properties of molecular heterostructures and beam-sensitive nanomaterials. In this study, we introduce a scanning transmission electron microscopy technique combining a pre-specimen phase plate designed to produce a probe with structured phase with a high-speed direct electron detector to generate nearly linear contrast images with high efficiency. We demonstrate this method by using both experiment and simulation to simultaneously image the atomic-scale structure of weakly scattering amorphous carbon and strongly scattering gold nanoparticles. Our method demonstrates strong contrast for both materials, making it a promising candidate for structural determination of heterogeneous soft/hard matter samples even at low electron doses comparable to traditional phase-contrast transmission electron microscopy. Simulated images demonstrate the extension of this technique to the challenging problem of structural determination of biological material at the surface of inorganic crystals.

  9. Investigation of Exchange Coupled Composites with Scanning Transmission X-ray Microscopy

    Full text: Novel exchange coupled composites incorporating a hard and a soft magnetic layer have the potential for a number of applications including magnetic recording, sensors, MRAM and oscillators. We investigate the magnetic behaviour of ferromagnetic L10 FePt thin films exchange coupled to soft ferrimagnets, including FeGd and FeTb, using Scanning Transmission X-ray Microscopy (STXM), which allows us to probe each layer individually, and magnetic force microscopy (MFM). Using a luminescence detection scheme, we are able to determine the magnetic domain configuration using STXM. From MFM measurements we find a compositional dependence of the domain structure in the ferrimagnetic films. (author)

  10. Compact scanning transmission x-ray microscope at the photon factory

    Takeichi, Yasuo, E-mail: yasuo.takeichi@kek.jp; Inami, Nobuhito; Ono, Kanta [High Energy Accelerator Research Organization (KEK), 1-1 Oho, Tsukuba 305-0801 (Japan); Suga, Hiroki [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Takahashi, Yoshio [Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)

    2016-01-28

    We report the design and performance of a compact scanning transmission X-ray microscope developed at the Photon Factory. Piezo-driven linear stages are used as coarse stages of the microscope to realize excellent compactness, mobility, and vibrational and thermal stability. An X-ray beam with an intensity of ∼10{sup 7} photons/s was focused to a diameter of ∼40 nm at the sample. At the soft X-ray undulator beamline used with the microscope, a wide range of photon energies (250–1600 eV) is available. The microscope has been used to research energy materials and in environmental sciences.

  11. Surface sensitivity in scanning transmission x-ray microspectroscopy using secondary electron detection.

    Hub, C; Wenzel, S; Raabe, J; Ade, H; Fink, R H

    2010-03-01

    The successful integration of electron detection into an existing scanning transmission x-ray microspectroscope (STXM) at the Swiss Light Source is demonstrated. In conventional x-ray detection using a photomultiplier, STXM offers mainly bulk sensitivity combined with high lateral resolution. However, by implementation of a channeltron electron multiplier, the surface sensitivity can be established by the detection of secondary electrons emitted from the sample upon resonant excitation. We describe the experimental setup and discuss several relevant aspects, in particular the schemes to correct for self-absorption in the specimen due to back illumination in case of thicker films. PMID:20370182

  12. Development of scanning transmission ion microscopy computed tomography at Fudan Microbeam line

    The computed tomography was applied to setting STIM (Scanning Transmission Ion Microscopy) projections recorded at the Fudan Ion Beam Laboratory. In this work, in order to visualize the three-dimensional mass density distribution in several specimens, example for a test structure of hollow gold cylinder was presented together with a detailed description of the developed system, including data reconstruction code (Tomorebuild 2) and image display software (AMIRA®). Future development will allow the particle induced X-ray emission tomography for elemental analysis of micrometer-sized samples. (authors)

  13. Reliable strain measurement in transistor arrays by robust scanning transmission electron microscopy

    Suhyun Kim

    2013-09-01

    Full Text Available Accurate measurement of the strain field in the channels of transistor arrays is critical for strain engineering in modern electronic devices. We applied atomic-resolution high-angle annular dark-field scanning transmission electron microscopy to quantitative measurement of the strain field in transistor arrays. The quantitative strain profile over 20 transistors was obtained with high reliability and a precision of 0.1%. The strain field was found to form homogeneously in the channels of the transistor arrays. Furthermore, strain relaxation due to the thin foil effect was quantitatively investigated for thicknesses of 35 to 275 nm.

  14. Compact scanning transmission x-ray microscope at the photon factory

    Takeichi, Yasuo; Inami, Nobuhito; Suga, Hiroki; Takahashi, Yoshio; Ono, Kanta

    2016-01-01

    We report the design and performance of a compact scanning transmission X-ray microscope developed at the Photon Factory. Piezo-driven linear stages are used as coarse stages of the microscope to realize excellent compactness, mobility, and vibrational and thermal stability. An X-ray beam with an intensity of ˜107 photons/s was focused to a diameter of ˜40 nm at the sample. At the soft X-ray undulator beamline used with the microscope, a wide range of photon energies (250-1600 eV) is available. The microscope has been used to research energy materials and in environmental sciences.

  15. Probing carbon coatings on nanoparticle decorated carbon nanotubes by scanning transmission X-ray microscopy

    Li, Ming; Gao, Jing; Bai, Lili; Pu, Aiwu; Liu, Jinyin; Zhao, Guanqi; Sun, Xuhui; Zhong, Jun, E-mail: jzhong@suda.edu.cn

    2013-11-15

    Two kinds of carbon coating on carbon nanotubes (CNTs) after decoration with nanoparticles were observed by scanning transmission X-ray microscopy with a concurrent characterization of the electronic structure, revealing the complex compositions in CNTs after chemical modification. Moreover, a sandwich structure shown as CNT-nanoparticle-coating can be created with the exposure to X-ray for CNTs decorated with nanoparticle outside the wall. The coating shows an effective way for site-selective modification of CNTs with various carbon structures.

  16. Scanning transmission x-ray microscope for materials science spectromicroscopy at the ALS

    Warwick, T.; Seal, S.; Shin, H. [Ernest Orlando Lawrence Berkeley National Lab., CA (United States)] [and others

    1997-04-01

    The brightness of the Advanced Light Source will be exploited by several new instruments for materials science spectromicroscopy over the next year or so. The first of these to become operational is a scanning transmission x-ray microscope with which near edge x-ray absorption spectra (NEXAFS) can be measured on spatial features of sub-micron size. Here the authors describe the instrument as it is presently implemented, its capabilities, some studies made to date and the developments to come. The Scanning Transmission X-ray Microscope makes use of a zone plate lens to produce a small x-ray spot with which to perform absorption spectroscopy through thin samples. The x-ray beam from ALS undulator beamline 7.0 emerges into the microscope vessel through a silicon nitride vacuum window 160nm thick and 300{mu}m square. The vessel is filled with helium at atmospheric pressure. The zone plate lens is illuminated 1mm downstream from the vacuum window and forms an image in first order of a pinhole which is 3m upstream in the beamline. An order sorting aperture passes the first order converging light and blocks the unfocused zero order. The sample is at the focus a few mm downstream of the zone plate and mounted from a scanning piezo stage which rasters in x and y so that an image is formed, pixel by pixel, by an intensity detector behind the sample. Absorption spectra are measured point-by-point as the photon energy is scanned by rotating the diffraction grating in the monochromator and changing the undulator gap.

  17. Transmission scans using Gd-153 line sources in cardiac SPECT studies: What is the additional patient radiation dose burden?

    Aim: To determine the contribution of transmission scan acquisition obtained for attenuation/scatter correction to total patient effective dose from cardiac SPECT studies. Materials and Methods: A dual-headed L-shaped gamma camera equipped with a transmission scan acquisition system based on two 153Gd line sources was used. Transmission scan acquisition was performed on a humanoid phantom. Thermoluminescence dosimeters were used to directly monitor the dose to 550 measuring points in the phantom. Patient effective dose and associated risk from transmission scans acquisition were estimated and compared to those associated to the radiopharmaceutical injected. Results: The maximum effective dose from a typical transmission measurements acquisition was 1.3 μSv and 1.9 μSv for male and female patients, respectively. The contribution of the typical transmission scans acquisition to total patient radiation risk from a cardiac SPECT study was less than 10-3. Conclusion: Radiation exposure may not be considered as a limiting factor for the clinical application of attenuation correction methods based on transmission measurements in cardiac SPECT

  18. Transmissive liquid-crystal device correcting primary coma aberration and astigmatism in laser scanning microscopy

    Tanabe, Ayano; Hibi, Terumasa; Ipponjima, Sari; Matsumoto, Kenji; Yokoyama, Masafumi; Kurihara, Makoto; Hashimoto, Nobuyuki; Nemoto, Tomomi

    2016-03-01

    Laser scanning microscopy allows 3D cross-sectional imaging inside biospecimens. However, certain aberrations produced can degrade the quality of the resulting images. We previously reported a transmissive liquid-crystal device that could compensate for the predominant spherical aberrations during the observations, particularly in deep regions of the samples. The device, inserted between the objective lens and the microscope revolver, improved the image quality of fixed-mouse-brain slices that were observed using two-photon excitation laser scanning microscopy, which was originally degraded by spherical aberration. In this study, we developed a transmissive device that corrects primary coma aberration and astigmatism, motivated by the fact that these asymmetric aberrations can also often considerably deteriorate image quality, even near the sample surface. The device's performance was evaluated by observing fluorescent beads using single-photon excitation laser scanning microscopy. The fluorescence intensity in the image of the bead under a cover slip tilted in the y-direction was increased by 1.5 times after correction by the device. Furthermore, the y- and z-widths of the imaged bead were reduced to 66% and 65%, respectively. On the other hand, for the imaged bead sucked into a glass capillary in the longitudinal x-direction, correction with the device increased the fluorescence intensity by 2.2 times compared to that of the aberrated image. In addition, the x-, y-, and z-widths of the bead image were reduced to 75%, 53%, and 40%, respectively. Our device successfully corrected several asymmetric aberrations to improve the fluorescent signal and spatial resolution, and might be useful for observing various biospecimens.

  19. High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy.

    Tate, Mark W; Purohit, Prafull; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

    2016-02-01

    We describe a hybrid pixel array detector (electron microscope pixel array detector, or EMPAD) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128×128 pixel detector consists of a 500 µm thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit. The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as local sample thickness can be directly determined. This paper describes the detector architecture, data acquisition system, and preliminary results from experiments with 80-200 keV electron beams. PMID:26750260

  20. High Dynamic Range Pixel Array Detector for Scanning Transmission Electron Microscopy

    Tate, Mark W; Chamberlain, Darol; Nguyen, Kayla X; Hovden, Robert M; Chang, Celesta S; Deb, Pratiti; Turgut, Emrah; Heron, John T; Schlom, Darrell G; Ralph, Daniel C; Fuchs, Gregory D; Shanks, Katherine S; Philipp, Hugh T; Muller, David A; Gruner, Sol M

    2015-01-01

    We describe a hybrid pixel array detector (EMPAD - electron microscope pixel array detector) adapted for use in electron microscope applications, especially as a universal detector for scanning transmission electron microscopy. The 128 x 128 pixel detector consists of a 500 um thick silicon diode array bump-bonded pixel-by-pixel to an application-specific integrated circuit (ASIC). The in-pixel circuitry provides a 1,000,000:1 dynamic range within a single frame, allowing the direct electron beam to be imaged while still maintaining single electron sensitivity. A 1.1 kHz framing rate enables rapid data collection and minimizes sample drift distortions while scanning. By capturing the entire unsaturated diffraction pattern in scanning mode, one can simultaneously capture bright field, dark field, and phase contrast information, as well as being able to analyze the full scattering distribution, allowing true center of mass imaging. The scattering is recorded on an absolute scale, so that information such as loc...

  1. Localization of human immunodeficiency virus antigens in infected cells by scanning/transmission-immunogold techniques

    An application of high resolution scanning/transmission electron microscopy (STEM) and gold-labelling techniques for the rapid detection of human immunodeficiency virus (HIV) in infected cells has been developed. Experimental in vitro studies for detecting two HIV structural proteins, gp41 and p17, were performed following an indirect labeling procedure that uses monoclonal anti-p17 and anti-gp41 antibodies as primary antibodies and 40 nm gold-linked goat antimouse IgG as secondary antibodies. The cells were then studied by STEM in the scanning mode. Unambiguous localization of the viral antigens was possible by combining the three-dimensional image provided by the secondary electron image and the atomic number-dependent backscattered electron image for the identification of the gold marker. This technique combines both the morphological information and the rapid procedures of scanning electron microscopy with the precise and sensitive antigen detection provided by the use of STEM and immunological methods. The preliminary results of its application to the study of peripheral blood mononuclear cells from four anti-HIV-seropositive patients showing the presence of specific labeling in all of them suggest that it might prove useful for early detection of HIV infection before seroconversion, as well as for quantitative studies

  2. Large-scale Scanning Transmission Electron Microscopy (Nanotomy) of Healthy and Injured Zebrafish Brain.

    Kuipers, Jeroen; Kalicharan, Ruby D; Wolters, Anouk H G; van Ham, Tjakko J; Giepmans, Ben N G

    2016-01-01

    Large-scale 2D electron microscopy (EM), or nanotomy, is the tissue-wide application of nanoscale resolution electron microscopy. Others and we previously applied large scale EM to human skin pancreatic islets, tissue culture and whole zebrafish larvae(1-7). Here we describe a universally applicable method for tissue-scale scanning EM for unbiased detection of sub-cellular and molecular features. Nanotomy was applied to investigate the healthy and a neurodegenerative zebrafish brain. Our method is based on standardized EM sample preparation protocols: Fixation with glutaraldehyde and osmium, followed by epoxy-resin embedding, ultrathin sectioning and mounting of ultrathin-sections on one-hole grids, followed by post staining with uranyl and lead. Large-scale 2D EM mosaic images are acquired using a scanning EM connected to an external large area scan generator using scanning transmission EM (STEM). Large scale EM images are typically ~ 5 - 50 G pixels in size, and best viewed using zoomable HTML files, which can be opened in any web browser, similar to online geographical HTML maps. This method can be applied to (human) tissue, cross sections of whole animals as well as tissue culture(1-5). Here, zebrafish brains were analyzed in a non-invasive neuronal ablation model. We visualize within a single dataset tissue, cellular and subcellular changes which can be quantified in various cell types including neurons and microglia, the brain's macrophages. In addition, nanotomy facilitates the correlation of EM with light microscopy (CLEM)(8) on the same tissue, as large surface areas previously imaged using fluorescent microscopy, can subsequently be subjected to large area EM, resulting in the nano-anatomy (nanotomy) of tissues. In all, nanotomy allows unbiased detection of features at EM level in a tissue-wide quantifiable manner. PMID:27285162

  3. 4D scanning transmission ultrafast electron microscopy: Single-particle imaging and spectroscopy.

    Ortalan, Volkan; Zewail, Ahmed H

    2011-07-20

    We report the development of 4D scanning transmission ultrafast electron microscopy (ST-UEM). The method was demonstrated in the imaging of silver nanowires and gold nanoparticles. For the wire, the mechanical motion and shape morphological dynamics were imaged, and from the images we obtained the resonance frequency and the dephasing time of the motion. Moreover, we demonstrate here the simultaneous acquisition of dark-field images and electron energy loss spectra from a single gold nanoparticle, which is not possible with conventional methods. The local probing capabilities of ST-UEM open new avenues for probing dynamic processes, from single isolated to embedded nanostructures, without being affected by the heterogeneous processes of ensemble-averaged dynamics. Such methodology promises to have wide-ranging applications in materials science and in single-particle biological imaging. PMID:21615171

  4. Stainless Steel Vacuum Chamber for Scanning Transmission X-ray Microsopy

    Kilcoyne, Arthur L.

    2016-07-05

    The stainless steel chamber was specifically conceived and designed for housing an interferometer controlled scanning transmission x-ray microscope (STXM). The construction of the chamber is such that internal components of the microscope rest within the chamber and are fixed to a 4 inch stainless steel belly band. The integral and most important part of the chamber is the belly band, which serves to isolate high frequency vibrations (e.g., floor surroundings, people traffic) from the sensitive measurements performed using the microscope. In addition, the chamber effectively acts as a sound barrier to the nanometer measurements conducted within. The assembled chamber (and microscope) are readily adjustable at the micron level using strut members external to the chamber but fixed to the belly band and a stand made of polymer concreate.

  5. Design and performance of a compact scanning transmission X-ray microscope at the Photon Factory

    Takeichi, Y., E-mail: yasuo.takeichi@kek.jp; Mase, K.; Ono, K. [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba 305-0801 (Japan); Department of Materials Structure Science, SOKENDAI (The Graduate University for Advanced Studies), 1-1 Oho, Tsukuba 305-0801 (Japan); Inami, N. [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba 305-0801 (Japan); Suga, H. [Department of Earth and Planetary Systems Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Miyamoto, C. [Department of Earth and Planetary Systems Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku 113-0033 (Japan); Ueno, T. [National Institute for Materials Science, 1-2-1 Sengen, Tsukuba 305-0047 (Japan); Takahashi, Y. [Institute of Materials Structure Science, High Energy Accelerator Research Organization, 1-1 Oho, Tsukuba 305-0801 (Japan); Department of Earth and Planetary Systems Science, Hiroshima University, 1-3-1 Kagamiyama, Higashi-Hiroshima 739-8526 (Japan); Department of Earth and Planetary Systems Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku 113-0033 (Japan)

    2016-01-15

    We present a new compact instrument designed for scanning transmission X-ray microscopy. It has piezo-driven linear stages, making it small and light. Optical components from the virtual source point to the detector are located on a single optical table, resulting in a portable instrument that can be operated at a general-purpose spectroscopy beamline without requiring any major reconstruction. Careful consideration has been given to solving the vibration problem common to high-resolution microscopy, so as not to affect the spatial resolution determined by the Fresnel zone plate. Results on bacteriogenic iron oxides, single particle aerosols, and rare-earth permanent magnets are presented as examples of its performance under diverse applications.

  6. New area detector for atomic-resolution scanning transmission electron microscopy.

    Shibata, Naoya; Kohno, Yuji; Findlay, Scott D; Sawada, Hidetaka; Kondo, Yukihito; Ikuhara, Yuichi

    2010-01-01

    A new area detector for atomic-resolution scanning transmission electron microscopy (STEM) is developed and tested. The circular detector is divided into 16 segments which are individually optically coupled with photomultiplier tubes. Thus, 16 atomic-resolution STEM images which are sensitive to the spatial distribution of scattered electrons on the detector plane can be simultaneously obtained. This new detector can be potentially used not only for the simultaneous formation of common bright-field, low-angle annular dark-field and high-angle annular dark-field images, but also for the quantification of images by detecting the full range of scattered electrons and even for exploring novel atomic-resolution imaging modes by post-processing combination of the individual images. PMID:20406732

  7. Probing plasmons in three dimensions in a scanning transmission electron microscope

    Hachtel, Jordan; Mouti, Anas; Mayo, Daniel; Marvinney, Claire; Mu, Richard; Haglund, Richard; Pennycook, Stephen; Chisholm, Matthew; Pantelides, Sokrates

    2015-03-01

    The optical behavior of nanostructured materials is of significant interest across many fields. Surface plasmons and their interactions with emitters in nanoscale devices allow us to control light below the coherence limit. By understanding the nature of plasmonics at the local level we can move towards unlocking the full potential of photonic devices. To this end, we examine plasmonic Ag nanoparticles suspended on insulating nanowires by combining cathodoluminescence spectroscopy, electron energy loss spectroscopy, and high resolution annular dark field imaging in a scanning transmission electron microscope. The complementary nature of CL and EELS allow us to extract optical data from a randomly shaped and oriented nanoparticle, and understand its plasmonic behavior in all three spatial dimensions. This work was sponsored by the US Department of Energy, Office of Science, Basic Energy Sciences, Materials Sciences and Engineering Division, as well as NSF-EPS-1004083 and NSF-TN-SCORE.

  8. Zone-Doubled Fresnel Zone Plates for Scanning Transmission X-ray Microscopy

    Vila-Comamala, J.; Gorelick, S.; Färm, E.; Kewish, C. M.; Diaz, A.; Guzenko, V. A.; Barrett, R.; Raabe, J.; Menzel, A.; Bunk, O.; Ritala, M.; David, C.

    2011-09-01

    We demonstrate the highest spatial resolution reported in scanning transmission x-ray microscopy to date. For the first time in x-ray microscopy, features below 10 nm in width were resolved in the soft x-ray regime (1.2 keV) and 20-nm lines and spaces were visible at multi-keV photon energies (6.2 keV). These achievements were accomplished using zone-doubled Fresnel zone plates. These lenses were fabricated by combining electron-beam lithography and atomic layer deposition of iridium. Diffraction efficiencies up to 8% were measured for zone-doubled Fresnel zone plates with an outermost zone width of 25 nm at 6.2-keV photon energy.

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

    Hachtel, J A; Marvinney, C; Mouti, A; Mayo, D; Mu, R; Pennycook, S J; Lupini, A R; Chisholm, M F; Haglund, R F; Pantelides, S T

    2016-04-15

    The nanoscale optical response of surface plasmons in three-dimensional metallic nanostructures plays an important role in many nanotechnology applications, where precise spatial and spectral characteristics of plasmonic elements control device performance. Electron energy loss spectroscopy (EELS) and cathodoluminescence (CL) within a scanning transmission electron microscope have proven to be valuable tools for studying plasmonics at the nanoscale. Each technique has been used separately, producing three-dimensional reconstructions through tomography, often aided by simulations for complete characterization. Here we demonstrate that the complementary nature of the two techniques, namely that EELS probes beam-induced electronic excitations while CL probes radiative decay, allows us to directly obtain a spatially- and spectrally-resolved picture of the plasmonic characteristics of nanostructures in three dimensions. The approach enables nanoparticle-by-nanoparticle plasmonic analysis in three dimensions to aid in the design of diverse nanoplasmonic applications. PMID:26934391

  10. Design and performance of a compact scanning transmission X-ray microscope at the Photon Factory.

    Takeichi, Y; Inami, N; Suga, H; Miyamoto, C; Ueno, T; Mase, K; Takahashi, Y; Ono, K

    2016-01-01

    We present a new compact instrument designed for scanning transmission X-ray microscopy. It has piezo-driven linear stages, making it small and light. Optical components from the virtual source point to the detector are located on a single optical table, resulting in a portable instrument that can be operated at a general-purpose spectroscopy beamline without requiring any major reconstruction. Careful consideration has been given to solving the vibration problem common to high-resolution microscopy, so as not to affect the spatial resolution determined by the Fresnel zone plate. Results on bacteriogenic iron oxides, single particle aerosols, and rare-earth permanent magnets are presented as examples of its performance under diverse applications. PMID:26827325

  11. Design and performance of a compact scanning transmission X-ray microscope at the Photon Factory

    Takeichi, Y.; Inami, N.; Suga, H.; Miyamoto, C.; Ueno, T.; Mase, K.; Takahashi, Y.; Ono, K.

    2016-01-01

    We present a new compact instrument designed for scanning transmission X-ray microscopy. It has piezo-driven linear stages, making it small and light. Optical components from the virtual source point to the detector are located on a single optical table, resulting in a portable instrument that can be operated at a general-purpose spectroscopy beamline without requiring any major reconstruction. Careful consideration has been given to solving the vibration problem common to high-resolution microscopy, so as not to affect the spatial resolution determined by the Fresnel zone plate. Results on bacteriogenic iron oxides, single particle aerosols, and rare-earth permanent magnets are presented as examples of its performance under diverse applications.

  12. Scanning Transmission X-ray Microscopy: Applications in Atmospheric Aerosol Research

    Moffet, Ryan C.; Tivanski, Alexei V.; Gilles, Mary K.

    2011-01-20

    Scanning transmission x-ray microscopy (STXM) combines x-ray microscopy and near edge x-ray absorption fine structure spectroscopy (NEXAFS). This combination provides spatially resolved bonding and oxidation state information. While there are reviews relevant to STXM/NEXAFS applications in other environmental fields (and magnetic materials) this chapter focuses on atmospheric aerosols. It provides an introduction to this technique in a manner approachable to non-experts. It begins with relevant background information on synchrotron radiation sources and a description of NEXAFS spectroscopy. The bulk of the chapter provides a survey of STXM/NEXAFS aerosol studies and is organized according to the type of aerosol investigated. The purpose is to illustrate the current range and recent growth of scientific investigations employing STXM-NEXAFS to probe atmospheric aerosol morphology, surface coatings, mixing states, and atmospheric processing.

  13. Identifying dislocations and stacking faults in GaN films by scanning transmission electron microscopy

    Su, X. J.; Niu, M. T.; Zeng, X. H.; Huang, J.; Zhang, J. C.; Zhang, J. P.; Wang, J. F.; Xu, K.

    2016-08-01

    The application of annular bright field (ABF) and medium-angle annular dark field (MAADF) scanning transmission electron microscopy (STEM) imaging to crystalline defect analysis has been extended to dislocations and stacking faults (SFs). Dislocations and SFs have been imaged under zone-axis and two-beam diffraction conditions. Comparing to conventional two-beam diffraction contrast images, the ABF and MAADF images of dislocations and SFs not only are complementary and symmetrical with their peaks at dislocation core and SFs plane, but also show similar extinction phenomenon. It is demonstrated that conventional TEM rules for diffraction contrast, i.e. g · b and g · R invisibility criteria remain applicable. The contrast mechanism and extinction of dislocation and SFs in ABF and MAADF STEM are illuminated by zero-order Laue zone Kikuchi diffraction.

  14. Design and performance of a compact scanning transmission X-ray microscope at the Photon Factory

    We present a new compact instrument designed for scanning transmission X-ray microscopy. It has piezo-driven linear stages, making it small and light. Optical components from the virtual source point to the detector are located on a single optical table, resulting in a portable instrument that can be operated at a general-purpose spectroscopy beamline without requiring any major reconstruction. Careful consideration has been given to solving the vibration problem common to high-resolution microscopy, so as not to affect the spatial resolution determined by the Fresnel zone plate. Results on bacteriogenic iron oxides, single particle aerosols, and rare-earth permanent magnets are presented as examples of its performance under diverse applications

  15. Imaging Polymer Nanostructures with Scanning Transmission X-ray Spectro-Microscopy

    Full text: Thin polymer films are of increasing technological importance in optoelectronic devices such as LEDs, lasers, FETs and solar cells. However, the morphology of such films is complex and the structure of the polymer film incorporated into a device can strongly affect its performance characteristics, e.g. via the connectedness between of polymer domains and to the device electrodes, or due to anisotropic material properties due to molecular alignment. Scanning transmission x-ray spectro-microscopy (STXM) has been demonstrated to be an excellent tool for the study of organic materials due to its high spatial resolution and strong contrast based on a variety of spectroscopic mechanisms. Recent work at the PolLux STXM has demonstrated a number of new developments, including both hardware upgrades and novel analysis methods. (author)

  16. Scanning transmission electron microscopic tomography of cortical bone using Z-contrast imaging.

    McNally, Elizabeth; Nan, Feihong; Botton, Gianluigi A; Schwarcz, Henry P

    2013-06-01

    Previously we presented (McNally et al., 2012) a model for the ultrastructure of bone showing that the mineral resides principally outside collagen fibrils in the form of 5 nm thick mineral structures hundreds of nanometers long oriented parallel to the fibrils. Here we use high-angle annular dark-field electron tomography in the scanning transmission electron microscope to confirm this model and further elucidate the composite structure. Views of a section cut parallel to the fibril axes show bundles of mineral structures extending parallel to the fibrils and encircling them. The mineral density inside the fibrils is too low to be visualized in these tomographic images. A section cut perpendicular to the fibril axes, shows quasi-circular walls composed of mineral structures, wrapping around apparently empty holes marking the sites of fibrils. These images confirm our original model that the majority of mineral in bone resides outside the collagen fibrils. PMID:23545162

  17. Non-destructive characterization of CMP pads using scanning ultrasonic transmission

    An automatic scanning ultrasonic transmission (UST) technique was developed and applied to nondestructive metrology and analysis of visco-elastic properties in full-size chemical mechanical planarization (CMP) pads prior to their use in CMP processing. The system is comprised of a specially designed ultrasonic transmitter as an emitter of acoustic vibrations and an ultrasonic probe as a receiver. Both, the transducer and the probe are positioned on the moving X-Z stage, while the circular pad is attached to a rotary motor. The probe is aligned with the center of the transmitter and measures with high accuracy and repeatability the amplitude of the transmitted ultrasonic vibrations through the pad at a pre-selected depth in the pad in the contact mode or at a certain elevation above the surface using non-contact mode. The UST system is computer controlled and fully automated. Inhomogeneity of commercial pads with a diameter up to 32'' were revealed and analyzed. Typical UST map exhibits almost regular stripes of high and low acoustic transmission, which are superimposed with global inhomogeneity where the UST amplitude changes circumferentially. Aside from the UST mapping, the system allows for the study of visco-elastic behavior of pad components using UST transient curves

  18. Revolving scanning transmission electron microscopy: Correcting sample drift distortion without prior knowledge

    We report the development of revolving scanning transmission electron microscopy – RevSTEM – a technique that enables characterization and removal of sample drift distortion from atomic resolution images without the need for a priori crystal structure information. To measure and correct the distortion, we acquire an image series while rotating the scan coordinate system between successive frames. Through theory and experiment, we show that the revolving image series captures the information necessary to analyze sample drift rate and direction. At atomic resolution, we quantify the image distortion using the projective standard deviation, a rapid, real-space method to directly measure lattice vector angles. By fitting these angles to a physical model, we show that the refined drift parameters provide the input needed to correct distortion across the series. We demonstrate that RevSTEM simultaneously removes the need for a priori structure information to correct distortion, leads to a dramatically improved signal-to-noise ratio, and enables picometer precision and accuracy regardless of drift rate. - Highlights: • We show that capturing a revolving series of STEM images can be used to measure drift parameters. • Lattice vector angles serve as an ideal metric of image distortion during the rotation. • Drift distortion correction can be done without any prior knowledge of the sample structure. • The method is independent of drift rate, and demonstrated using a sample drifting at 0.5 nm/s. • The revolving series enables precise and accurate atom column location information across the entire image

  19. A high-speed area detector for novel imaging techniques in a scanning transmission electron microscope

    A scanning transmission electron microscope (STEM) produces a convergent beam electron diffraction pattern at each position of a raster scan with a focused electron beam, but recording this information poses major challenges for gathering and storing such large data sets in a timely manner and with sufficient dynamic range. To investigate the crystalline structure of materials, a 16x16 analog pixel array detector (PAD) is used to replace the traditional detectors and retain the diffraction information at every STEM raster position. The PAD, unlike a charge-coupled device (CCD) or photomultiplier tube (PMT), directly images 120-200 keV electrons with relatively little radiation damage, exhibits no afterglow and limits crosstalk between adjacent pixels. Traditional STEM imaging modes can still be performed by the PAD with a 1.1 kHz frame rate, which allows post-acquisition control over imaging conditions and enables novel imaging techniques based on the retained crystalline information. Techniques for rapid, semi-automatic crystal grain segmentation with sub-nanometer resolution are described using cross-correlation, sub-region integration, and other post-processing methods.

  20. Helium Scanning Transmission Ion Microscopy and Electrical Characterization of Glass Nanocapillaries with Reproducible Tip Geometries.

    Zweifel, Ludovit P; Shorubalko, Ivan; Lim, Roderick Y H

    2016-02-23

    Nanopores fabricated from glass microcapillaries are used in applications ranging from scanning ion conductance microscopy to single-molecule detection. Still, evaluating the nanocapillary tip by a noninvasive means remains challenging. For instance, electron microscopy characterization techniques can charge, heat, and contaminate the glass surface and typically require conductive coatings that influence the final tip geometry. Per contra, electrical characterization by the means of ion current through the capillary lumen provides only indirect geometrical details of the tips. Here, we show that helium scanning transmission ion microscopy provides a nondestructive and precise determination of glass nanocapillary tip geometries. This enables the reproducible fabrication of axially asymmetric blunt, bullet, and hourglass-shaped tips with opening diameters from 20 to 400 nm by laser-assisted pulling. Accordingly, this allows for an evaluation of how tip shape, pore diameter, and opening angle impact ionic current rectification behavior and the translocation of single molecules. Our analysis shows that current drops and translocation dwell times are dominated by the pore diameter and opening angles regardless of nanocapillary tip shape. PMID:26783633

  1. A high-speed area detector for novel imaging techniques in a scanning transmission electron microscope.

    Caswell, T A; Ercius, P; Tate, M W; Ercan, A; Gruner, S M; Muller, D A

    2009-03-01

    A scanning transmission electron microscope (STEM) produces a convergent beam electron diffraction pattern at each position of a raster scan with a focused electron beam, but recording this information poses major challenges for gathering and storing such large data sets in a timely manner and with sufficient dynamic range. To investigate the crystalline structure of materials, a 16x16 analog pixel array detector (PAD) is used to replace the traditional detectors and retain the diffraction information at every STEM raster position. The PAD, unlike a charge-coupled device (CCD) or photomultiplier tube (PMT), directly images 120-200keV electrons with relatively little radiation damage, exhibits no afterglow and limits crosstalk between adjacent pixels. Traditional STEM imaging modes can still be performed by the PAD with a 1.1kHz frame rate, which allows post-acquisition control over imaging conditions and enables novel imaging techniques based on the retained crystalline information. Techniques for rapid, semi-automatic crystal grain segmentation with sub-nanometer resolution are described using cross-correlation, sub-region integration, and other post-processing methods. PMID:19162398

  2. NanoXAS—The in situ Combination of Scanning Transmission X‐ray and Scanning Probe Microscopy

    Schmid, I; J. Raabe; Wenzel, S.; Fink, R; Hug, H; Quitmann, C.

    2012-01-01

    NanoXAS is a novel x‐ray microscope installed at the Swiss Light Source combining laterally resolved soft x‐ray spectroscopy with scanning probe microscopy. We report on first in situ studies from thin polymer blend films and magnetic materials where topographic and spectroscopic contrast are used and show how complementary imaging modes provide new insight into many materials. In the future the scanning probe tip will be used to collect photoelectrons. By this we expect a spatial resolution ...

  3. The effect, identification and correction of misalignment between PET transmission and emission scans on brain PET imaging

    Objectives: To study the effect of misalignment between PET transmission and emission scans of brain on brain PET imaging, and the Methods to identify and correct it. Methods: 18F-FDG PET imaging was performed on 8 volunteers. The emission images were reconstructed with attenuation correction after some translations and rotations in the x-axis and transverse plane were given, 1 mm and 1 degree each step, respectively. The 3-D volume fusion of PET emission and transmission scans was used to identify the suspected misalignment on 10 18F-FDG PET brain imaging. Three Methods were used to correct the misalignment. First, to quantitate the amount of the misalignment by 3-D volume registration of PET emission and transmission scans, the emission images were reconstructed with corrected translations and rotations in x-direction and transverse plane. Second, the emission images were reconstructed with mathematic calculation of brain attenuation. Third, 18F-FDG PET brain imaging was redone with careful application of laser alignment. Results: The translations greater than 3 mm in x-direction and the rotations greater than 8 degrees in transverse plane could lead to visible artifacts, which were presented with decreasing radioactivity uptake in the cortex of half cerebrum and in the frontal cortex at the side in the translating or rotating direction, respectively. The 3-D volume fusion of PET emission and transmission scans could identify and quantitate the amount of misalignment between PET emission and transmission scans of brain. The PET emission images reconstructed with corrected misalignment and mathematic calculation of brain attenuation were consistent with redone PET brain imaging. Conclusions: The misalignment between PET transmission and emission scans of brain can lead to visible artifacts. The 3-D volume fusion of PET emission and transmission scans can identify and quantitate the amount of the misalignment. The visible artifacts caused by the misalignment can be

  4. Development of a scanning transmission x-ray microscope for the beamline P04 at PETRA III DESY

    Andrianov, Konstantin; Ewald, Johannes; Nisius, Thomas; Wilhein, Thomas [Institute for X-Optics, University of Applied Sciences Koblenz-RheinAhrCampus, Joseph-Rovan-Allee 2, 53424 Remagen (Germany); Lühl, Lars; Malzer, Wolfgang; Kanngießer, Birgit [Institute of Optics and Atomic Physics, Technical University of Berlin, Hardenbergstr. 36, 10623 Berlin (Germany)

    2016-01-28

    We present a scanning transmission x-ray microscope (STXM) built on top of our existing modular platform for high resolution imaging experiments. This platform consists of up to three separate vacuum chambers and custom designed piezo stages. These piezo stages are able to move precisely in x-, y- and z-direction, this makes it possible to adjust the components for different imaging modes. During recent experiments the endstation was operated mainly as a transmission x-ray microscope (TXM) [1, 2].

  5. Advanced scanning transmission stereo electron microscopy of structural and functional engineering materials

    Stereo transmission electron microscopy (TEM) provides a 3D impression of the microstructure in a thin TEM foil. It allows to perform depth and TEM foil thickness measurements and to decide whether a microstructural feature lies inside of a thin foil or on its surface. It allows appreciating the true three-dimensional nature of dislocation configurations. In the present study we first review some basic elements of classical stereo TEM. We then show how the method can be extended by working in the scanning transmission electron microscope (STEM) mode of a modern analytical 200 kV TEM equipped with a field emission gun (FEG TEM) and a high angle annular dark field (HAADF) detector. We combine two micrographs of a stereo pair into one anaglyph. When viewed with special colored glasses the anaglyph provides a direct and realistic 3D impression of the microstructure. Three examples are provided which demonstrate the potential of this extended stereo TEM technique: a single crystal Ni-base superalloy, a 9% Chromium tempered martensite ferritic steel and a NiTi shape memory alloy. We consider the effect of camera length, show how foil thicknesses can be measured, and discuss the depth of focus and surface effects. -- Highlights: ► The advanced STEM/HAADF diffraction contrast is extended to 3D stereo-imaging. ► The advantages of the new technique over stereo-imaging in CTEM are demonstrated. ► The new method allows foil thickness measurements in a broad range of conditions. ► We show that features associated with ion milling surface damage can be beneficial for appreciating 3D features of the microstructure.

  6. The scanning transmission x-ray microscope at the NSLS: From XANES to cryo

    The Stony Brook scanning transmission x-ray microscope (STXM) has been operated at the XIA beamline at the NSLS since 1989. A large number of users have used it to study biological and material science samples. The authors report on changes that have been performed in the past year, and present recent results. To stabilize the position of the micro probe when doing spectral scans at high spatial resolution, they have constructed a piezo-driven flexure stage which carries out the focusing motion of the zone plate needed when changing the wavelength. To overcome the detector limitation set by saturation of the gas-flow counter at count rates around 1 MHz, they are installing an avalanche photo diode with an active quenching circuit which they expect to respond linearly to count rates in excess of 10 MHz. They have improved the enclosure for STXM to improve the stability of the Helium atmosphere while taking data. This reduces fluctuations of beam absorption and, therefore, noise in the image. A fast shutter has been installed in the beam line. The authors are also developing a cryo-STXM which is designed for imaging frozen hydrated samples at temperatures below 120 K. At low temperatures, radiation sensitive samples can tolerate a considerably higher radiation dose than at room temperature. This should improve the resolution obtainable from biological samples and should make recording of multiple images of the same sample area possible while minimizing the effects of radiation damage. This should enable them to perform elemental and chemical mapping at high resolution, and to record the large number of views needed for 3D reconstruction of the object

  7. Rare-earth-doped nanophosphors for multicolor cathodoluminescence nanobioimaging using scanning transmission electron microscopy

    Furukawa, Taichi; Fukushima, Shoichiro; Niioka, Hirohiko; Yamamoto, Naoki; Miyake, Jun; Araki, Tsutomu; Hashimoto, Mamoru

    2015-05-01

    We describe rare-earth-doped nanophosphors (RE-NPs) for biological imaging using cathodoluminescence (CL) microscopy based on scanning transmission electron microscopy (STEM). We report the first demonstration of multicolor CL nanobioimaging using STEM with nanophosphors. The CL spectra of the synthesized nanophosphors (Y2O3:Eu, Y2O3:Tb) were sufficiently narrow to be distinguished. From CL images of RE-NPs on an elastic carbon-coated copper grid, the spatial resolution was beyond the diffraction limit of light. Y2O3:Tb and Y2O3:Eu RE-NPs showed a remarkable resistance against electron beam exposure even at high acceleration voltage (80 kV) and retained a CL intensity of more than 97% compared with the initial intensity for 1 min. In biological CL imaging with STEM, heavy-metal-stained cell sections containing the RE-NPs were prepared, and both the CL images of RE-NPs and cellular structures, such as mitochondria, were clearly observed from STEM images with high contrast. The cellular CL imaging using RE-NPs also had high spatial resolution even though heavy-metal-stained cells are normally regarded as highly scattering media. Moreover, since the RE-NPs exhibit photoluminescence (PL) excited by UV light, they are useful for multimodal correlative imaging using CL and PL.

  8. Scanning transmission ion microscopy computed tomography (STIM-CT) for inertial confinement fusion (ICF) targets

    Highlights: ► ICF target quality requires surface finishes on the order of submicron-scale. ► In STIM inner and outer wall profile can be mapped. ► In STIM the thickness and nonconcentricity of shell-wall in ICF targets can be measured. ► STIM-CT is a powerful method for obtaining three-dimensional density maps within ICF targets. ► STIM-CT can obtain internal structure with identifying non-uniformities in the ICF targets. -- Abstract: ICF target quality control in the laser fusion program is vital to ensure that the energy deposition from the lasers results in uniform compression and minimization of Rayleigh–Taylor instabilities, which requires surface finishes on the order of submicron-scale. During target fabrication process the surface finish and the dimensions of the hohlraum need be well controlled. Density variations and nonspherical or nonconcentric shells might be produced. Scanning transmission ion microscopy computed tomography (STIM-CT) is able to reconstruct the three-dimensional quantitative structure of ICF targets a few tens of micrometers in size. Compared to other types of probe techniques, the main advantage of STIM-CT is that quantitative information about mass density and sphericity can be obtained directly and non-destructively, utilizing specific reconstruction codes. We present a case of ICF target (composed of polyvinyl alcohol) characterization by STIM-CT in order to demonstrate the STIM-CT potential impact in assessing target fabrication processes

  9. Characterizing automotive fuel cell materials by soft x-ray scanning transmission x-ray microscopy

    Hitchcock, A. P.; Lee, V.; Wu, J.; West, M. M.; Cooper, G.; Berejnov, V.; Soboleva, T.; Susac, D.; Stumper, J.

    2016-01-01

    Proton-Exchange Membrane Fuel Cell (PEM-FC) based engines are being developed rapidly for near-term implementation in hydrogen fueled, mass production, personal automobiles. Research is focused on understanding and controlling various degradation processes (carbon corrosion, Pt migration, cold start), and reducing cost by reducing or eliminating Pt catalyst. We are using soft X-ray scanning transmission X-ray microscopy (STXM) at the S 2p, C 1s, O 1s and F 1s edges to study a variety of issues related to optimization of PEM-FC materials for automotive applications. A method to efficiently and accurately measure perfluorosulfonic acid distributions was developed and is being used to better understand how different loadings and preparation methods affect the ionomer distribution in the cathode. Progress towards an environmental cell capable of controlling the temperature and humidity of a PEM-FC sample in the STXM is described. Methods for studying the 3D chemical structure of PEM-FC are outlined.

  10. Characterizing automotive fuel cell materials by soft x-ray scanning transmission x-ray microscopy

    Hitchcock, A. P., E-mail: aph@mcmaster.ca; Lee, V.; Wu, J.; Cooper, G. [Chemistry & Chemical Biology, McMaster University, Hamilton, ON, L8S 4M1 (Canada); West, M. M.; Berejnov, V. [Faculty of Health Sciences Electron Microscopy, McMaster University, Hamilton, ON L8N 3Z5 (Canada); Soboleva, T.; Susac, D.; Stumper, J. [Automotive Fuel Cell Cooperation Corp., Burnaby BC V5J 5J8 (Canada)

    2016-01-28

    Proton-Exchange Membrane Fuel Cell (PEM-FC) based engines are being developed rapidly for near-term implementation in hydrogen fueled, mass production, personal automobiles. Research is focused on understanding and controlling various degradation processes (carbon corrosion, Pt migration, cold start), and reducing cost by reducing or eliminating Pt catalyst. We are using soft X-ray scanning transmission X-ray microscopy (STXM) at the S 2p, C 1s, O 1s and F 1s edges to study a variety of issues related to optimization of PEM-FC materials for automotive applications. A method to efficiently and accurately measure perfluorosulfonic acid distributions was developed and is being used to better understand how different loadings and preparation methods affect the ionomer distribution in the cathode. Progress towards an environmental cell capable of controlling the temperature and humidity of a PEM-FC sample in the STXM is described. Methods for studying the 3D chemical structure of PEM-FC are outlined.

  11. Argentinian multi-wavelength scanning Raman lidar to observe night sky atmospheric transmission

    Pallotta, Juan; Otero, Lidia; Chouza, Fernando; Raul, Delia; Gonzalez, Francisco; Etchegoyen, Alberto; Quel, Eduardo

    2013-01-01

    This paper discusses the multi-wavelength scanning Raman lidar being built at Lidar Division, CEILAP (CITEDEF-CONICET) in the frame of the Argentinean Cherenkov Telescope Array (CTA) collaboration to measure the spectral characteristics of the atmospheric aerosol extinction profiles to provide better transmission calculations at the future CTA site. This lidar emits short laser pulses of 7-9 ns at 355, 532 and 1064 nm at 50 Hz with nominal energy of 125 mJ at 1064 nm. This wavelengths are also used to retrieve the atmospheric (air, aerosol and clouds) backscattered radiation in the UV, VIS and IR ranges. Raman capabilities were added in the UV and VIS wavelengths to retrieve the spectral characteristics of the aerosol extinction and the water vapor profile. Due to the expected low aerosol optical depth of the future site, the short observation period as well as the extension of the observation, an enhanced collection area is required. This system uses six 40 cm f/2.5 newtonian telescopes to avoid dealing with...

  12. Common Bias Readout for TES Array on Scanning Transmission Electron Microscope

    Yamamoto, R.; Sakai, K.; Maehisa, K.; Nagayoshi, K.; Hayashi, T.; Muramatsu, H.; Nakashima, Y.; Mitsuda, K.; Yamasaki, N. Y.; Takei, Y.; Hidaka, M.; Nagasawa, S.; Maehata, K.; Hara, T.

    2016-03-01

    A transition edge sensor (TES) microcalorimeter array as an X-ray sensor for a scanning transmission electron microscope system is being developed. The technical challenge of this system is a high count rate of ˜ 5000 counts/second/array. We adopted a 64 pixel array with a parallel readout. Common SQUID bias, and common TES bias are planned to reduce the number of wires and the resources of a room temperature circuit. The reduction rate of wires is 44 % when a 64 pixel array is read out by a common bias of 8 channels. The possible degradation of the energy resolution has been investigated by simulations and experiments. The bias fluctuation effects of a series connection are less than those of a parallel connection. Simple calculations expect that the fluctuations of the common SQUID bias and common TES bias in a series connection are 10^{-7} and 10^{-3} , respectively. We constructed 8 SQUIDs which are connected to 8 TES outputs and a room temperature circuit for common bias readout and evaluated experimentally. Our simulation of crosstalk indicates that at an X-ray event rate of 500 cps/pixel, crosstalk will broaden a monochromatic line by about 0.01 %, or about 1.5 eV at 15 keV. Thus, our design goal of 10 eV energy resolution across the 0.5-15 keV band should be achievable.

  13. Characterizing automotive fuel cell materials by soft x-ray scanning transmission x-ray microscopy

    Proton-Exchange Membrane Fuel Cell (PEM-FC) based engines are being developed rapidly for near-term implementation in hydrogen fueled, mass production, personal automobiles. Research is focused on understanding and controlling various degradation processes (carbon corrosion, Pt migration, cold start), and reducing cost by reducing or eliminating Pt catalyst. We are using soft X-ray scanning transmission X-ray microscopy (STXM) at the S 2p, C 1s, O 1s and F 1s edges to study a variety of issues related to optimization of PEM-FC materials for automotive applications. A method to efficiently and accurately measure perfluorosulfonic acid distributions was developed and is being used to better understand how different loadings and preparation methods affect the ionomer distribution in the cathode. Progress towards an environmental cell capable of controlling the temperature and humidity of a PEM-FC sample in the STXM is described. Methods for studying the 3D chemical structure of PEM-FC are outlined

  14. Characterising the surface and interior chemistry of core-shell nanoparticles using scanning transmission electron microscopy

    A method for extracting core and shell spectra from core-shell particles with varying core to shell volume fractions is described. The method extracts the information from a single EELS spectrum image of the particle. The distribution of O and N was correctly reproduced for a nanoparticle with a TiN core and Ti-oxide shell. In addition, the O distribution from a nanoparticle with a Cu core and a Cu-oxide shell was obtained, and the extracted Cu L2,3-core and shell spectra showed the required change in EELS near edge fine structure. The extracted spectra can be used for multiple linear least squares fitting to the raw data in the spectrum image. The effect of certain approximations on numerical accuracy, such as treating the nanoparticle as a perfect sphere, as well as the intrinsic detection limits of the technique have also been explored. The technique is most suitable for qualitative, rather than quantitative, work. -- Research Highlights: → A new method for extracting core and shell EELS spectra from a core-shell nanoparticle is developed. → The technique utilises spectrum imaging in a scanning transmission electron microscope (STEM). → The composition and bonding environment at the core and shell regions can be analysed.→ The method is applied to TiN/Ti-oxide and Cu/Cu-oxide core-shell nanoparticles.→ Numerical accuracy and intrinsic limits of the technique are also discussed.

  15. Sub-Angstrom metrology of resolution in aberration-corrected transmission electron microscopes using the A-OK standard test specimens

    Allard, Lawrence F.; O' Keefe, Michael A.

    2004-07-01

    Using specimens with diamond cubic and zincblende structures, oriented to provide pairs of atoms in ''dumbbell'' configurations, we have identified specimens with well-characterized atom separations over a 3:1 range of spacings straddling the canonical 1 Angstrom value. Spacings ranging from 1.6 Angstrom to 0.5 Angstrom are available from an ''A-OK'' set of test specimens carefully selected for their stability and well-characterized lattice parameters.

  16. Composition mapping in InGaN by scanning transmission electron microscopy

    We suggest a method for chemical mapping that is based on scanning transmission electron microscopy (STEM) imaging with a high-angle annular dark field (HAADF) detector. The analysis method uses a comparison of intensity normalized with respect to the incident electron beam with intensity calculated employing the frozen lattice approximation. This procedure is validated with an In0.07Ga0.93N layer with homogeneous In concentration, where the STEM results were compared with energy filtered imaging, strain state analysis and energy dispersive X-ray analysis. Good agreement was obtained, if the frozen lattice simulations took into account static atomic displacements, caused by the different covalent radii of In and Ga atoms. Using a sample with higher In concentration and series of 32 images taken within 42 min scan time, we did not find any indication for formation of In rich regions due to electron beam irradiation, which is reported in literature to occur for the parallel illumination mode. Image simulation of an In0.15Ga0.85N layer that was elastically relaxed with empirical Stillinger-Weber potentials did not reveal significant impact of lattice plane bending on STEM images as well as on the evaluated In concentration profiles for specimen thicknesses of 5, 15 and 50 nm. Image simulation of an abrupt interface between GaN and In0.15Ga0.85N for specimen thicknesses up to 200 nm showed that artificial blurring of interfaces is significantly smaller than expected from a simple geometrical model that is based on the beam convergence only. As an application of the method, we give evidence for the existence of In rich regions in an InGaN layer which shows signatures of quantum dot emission in microphotoluminescence spectroscopy experiments. -- Highlights: → Composition mapping in InGaN using quantitative STEM. → No electron beam induced In clustering in InGaN observed for STEM. → Small influence of lattice plane bending for STEM of InGaN/GaN. → In composition

  17. Atom location using scanning transmission electron microscopy based on electron energy loss spectroscopy

    Full text: The technique of atom location by channelling enhanced microanalysis (ALCHEMI) using cross section data, measured as a function of electron beam orientation, has been widely implemented by many researchers. The accurate application of ALCHEMI, usually based on energy dispersive x-ray analysis (EDX), requires knowledge, from first principles, of the relative delocalization of the inner-shell ionization interaction (see for example Oxley and Allen, 1998; Oxley et al., 1999). Scanning transmission electron microscopy (STEM) based on electron energy loss spectroscopy (EELS) also provides information about the location of atoms of different types within the crystal lattice. Unlike high angle annular dark field (HAADF), EELS provides a unique signal for each atom type. In conjunction with highly focused probes, allowing near atomic resolution, this makes possible, in principle, the application of ALCHEMI like techniques to STEM images to determine the distribution of impurities within the unit cell. The accurate interpretation of STEM results requires that both the inner-shell ionization interaction and resulting ionization cross section or image be correctly modelled. We present model calculations demonstrating the in principle application of ALCHEMI type techniques to STEM images pertinent to EELS. The inner-shell ionisation interaction is modelled using Hartree-Fock wave functions to describe the atomic bound states and Hartree-Slater wave functions to describe the continuum states. The wave function within the crystal is calculated using boundary conditions appropriate for a highly focussed probe (Rossouw and Allen, 2001) and STEM images or ionisation cross sections are simulated using an inelastic cross section formulation that correctly accounts for the contribution from both dynamical electrons and those dechannelled by absorptive scattering processes such as thermal diffuse scattering (TDS). Copyright (2002) Australian Society for Electron Microscopy

  18. Analysis of environmental particles by atomic force microscopy, scanning and transmission electron microscopy.

    Mavrocordatos, D; Pronk, W; Boiler, M

    2004-01-01

    Due to their large specific surface and their abundance, micro and nano particles play an important role in the transport of micropollutants in the environment. Natural particles are usually composed of a mixture of inorganic amorphous or crystalline material (mainly FeOOH, Fe(x)Oy, Mn(x)Oy and clays) and organic material (humics and polysaccharides). They all tend to occur as very small particles (1-1,000 nm in diameter). Most natural amorphous particles are unstable and tend to transform with time towards more crystalline forms, either by aging or possibly, by dissolution and re-crystallization. Such transformations affect the fate of sorbed micropollutants and the scavenging properties are therefore changed. As these entities are sensitive to dehydration (aggregation, changes in the morphology), it is highly important to observe their morphology in their natural environment and understand their composition at the scale of the individual particles. Also for the understanding and optimization of water treatment technologies, the knowledge of the occurrence and behavior of nano-particles is of high importance. Some of the possible particle analysis methods are presented: aggregation processes, biomineralization, bacterial adhesion, biofilms in freshwaters, ferrihydrite as heavy metals remover from storm water. These examples demonstrate the capabilities and focus of the microscopes. Atomic Force Microscopy (AFM) allows to analyze the particles in their own environment, meaning in air or in the water. Thus, native aspects of particles can be observed. As well, forces of interactions between particles or between particles and other surfaces such as membranes will be highly valuable data. Scanning Electron Microscopy (SEM) and for higher lateral resolution, Transmission Electron Microscopy (TEM) allow measurement of the morphology and composition. Especially, TEM coupled with Electron Energy Loss Spectroscopy (TEM-EELS) is a powerful technique for elemental analysis

  19. Soft X-ray scanning transmission X-ray microscopy (STXM) of actinide particles.

    Nilsson, Hans J; Tyliszczak, Tolek; Wilson, Richard E; Werme, Lars; Shuh, David K

    2005-09-01

    A descriptive account is given of our most recent research on the actinide dioxides with the Advanced Light Source Molecular Environmental Science (ALS-MES) Beamline 11.0.2 soft X-ray scanning transmission X-ray microscope (STXM) at the Lawrence Berkeley National Laboratory (LBNL). The ALS-MES STXM permits near-edge X-ray absorption fine structure (NEXAFS) and imaging with 30-nm spatial resolution. The first STXM spectromicroscopy NEXAFS spectra at the actinide 4d5/2 edges of the imaged transuranic particles, NpO2 and PuO2, have been obtained. Radiation damage induced by the STXM was observed in the investigation of a mixed oxidation state particle (Np(V,VI)) and was minimized during collection of the actual spectra at the 4d5/2 edge of the Np(V,VI) solid. A plutonium elemental map was obtained from an irregular PuO2 particle with the dimensions of 650 x 650 nm. The Pu 4d5/2 NEXAFS spectra were collected at several different locations from the PuO2 particle and were identical. A representative oxygen K-edge spectrum from UO2 was collected and resembles the oxygen K-edge from the bulk material. The unique and current performance of the ALS-MES STXM at extremely low energies (ca. 100 eV) that may permit the successful measurement of the actinide 5d edge is documented. Finally, the potential of STXM as a tool for actinide investigations is briefly discussed. PMID:16021423

  20. Morphology and ultrastructure of Brachymystax lenok tsinlingensis spermatozoa by scanning and transmission electron microscopy.

    Guo, Wei; Shao, Jian; Li, Ping; Wu, Jinming; Wei, Qiwei

    2016-08-01

    This study was conducted to investigate Brachymystax lenok tsinlingensis spermatozoa cell morphology and ultrastructure through scanning and transmission electron microscopy. Findings revealed that the spermatozoa can be differentiated into three major parts: a spherical head without an acrosome, a short mid-piece, and a long, cylindrical flagellum. The mean length of the spermatozoa was 36.11±2.84μm, with a spherical head length of 2.78±0.31μm. The mean anterior and posterior head widths were 2.20±0.42μm and 2.55±0.53μm, respectively. The nuclear fossa was positioned at the base of the nucleus that contained the anterior portion of flagellum and a centriolar complex (proximal and distal centrioles). The short mid-piece was located laterally to the nucleus and possessed just one spherical mitochondrion with a mean diameter of 0.65±0.14μm. The spermatozoa flagellum was long and cylindrical, and could be separated into two parts: a long main-piece and a short end-piece. The main piece of the flagellum had short irregular side-fins. The axoneme composed the typical '9+2' microtubular doublet structure and was enclosed by the cell membran e. This study confirmed that B. lenok tsinlingensis spermatozoa can be categorized as teleostean "Type I" spermatozoa; 'primitive' or 'ect-aquasperm type' spermatozoa. To the best of the authers knowledge, this was the first study conducted on the morphology and ultrastructure of B. lenok tsinlingensis spermatozoa. PMID:27375213

  1. 3-d chemical imaging using angle-scan nanotomography in a soft X-ray scanning transmission X-ray microscope

    Three-dimensional chemical mapping using angle scan nanotomography in a soft X-ray scanning transmission X-ray microscope (STXM) has been used to investigate the spatial distributions of a low density polyacrylate polyelectrolyte ionomer inside submicron sized polystyrene microspheres. Acquisition of tomograms at multiple photon energies provides true, quantifiable 3-d chemical sensitivity. Both pre-O 1s and C 1s results are shown. The study reveals aspects of the 3-d distribution of the polyelectrolyte that were inferred indirectly or had not been known prior to this study. The potential and challenges for extension of the technique to studies of other polymeric and to biological systems is discussed. (orig.)

  2. Construction of a scanning transmission X-ray microscope at the undulator U-41 at BESSY II

    Wiesemann, U; Frueke, R; Guttmann, P; Niemann, B; Rudolph, D; Schmahl, G

    2001-01-01

    A new scanning transmission X-ray microscope for the soft X-ray region is under construction at the BESSY II storage ring. The radiation from the undulator U-41 is monochromatized with a monochromator consisting of a plane mirror and a plane grating with varied line density. For a high resolution image, the zone plate is scanned with a piezoelectric flexure stage. The X-ray flux in the focal spot will be of the order of 10 sup 9 photons/s. The sample is located in air. A pn-CCD detector is used to measure the transmitted intensity.

  3. Simultaneous fluorescence and high-resolution bright-field imaging with aberration correction over a wide field-of-view with Fourier ptychographic microscopy (FPM) (Conference Presentation)

    Chung, Jaebum; Kim, Jinho; Ou, Xiaoze; Horstmeyer, Roarke; Yang, Changhuei

    2016-03-01

    We present a method to acquire both fluorescence and high-resolution bright-field images with correction for the spatially varying aberrations over a microscope's wide field-of-view (FOV). First, the procedure applies Fourier ptychographic microscopy (FPM) to retrieve the amplitude and phase of a sample, at a resolution that significantly exceeds the cutoff frequency of the microscope objective lens. At the same time, FPM algorithm is able to leverage on the redundancy within the set of acquired FPM bright-field images to estimate the microscope aberrations, which usually deteriorate in regions further away from the FOV's center. Second, the procedure acquires a raw wide-FOV fluorescence image within the same setup. Lack of moving parts allows us to use the FPM-estimated aberration map to computationally correct for the aberrations in the fluorescence image through deconvolution. Overlaying the aberration-corrected fluorescence image on top of the high-resolution bright-field image can be done with accurate spatial correspondence. This can provide means to identifying fluorescent regions of interest within the context of the sample's bright-field information. An experimental demonstration successfully improves the bright-field resolution of fixed, stained and fluorescently tagged HeLa cells by a factor of 4.9, and reduces the error caused by aberrations in a fluorescence image by 31%, over a field of view of 6.2 mm by 9.3 mm. For optimal deconvolution, we show the fluorescence image needs to have a signal-to-noise ratio of ~18.

  4. IN VITRO ACTION OF COBRA VENOM ON GOAT SPERMATOZOA ULTRASTRUCTURE BY TRANSMISSION AND SCANNING ELECTRON MICROSCOPY

    T. R. RAHMY

    2002-01-01

    Full Text Available Goat spermatozoa were incubated in vitro in Tris-citrate buffer, pH 7.2, containing 0, 40, 80, or 160 mug of Naja haje venom/mL buffer for 4 hours. During incubation, the percentages of sperm motility were decreased, while percentages of dead spermatozoa were increased in a time and concentration-dependent manner. The effect of venom concentrations on the ultrastructure of incubated spermatozoa was examined hourly by scanning (SEM and transmission (TEM electron microscopy. SEM results showed plasma membrane wrinkling at heads of some spermatozoa after 2 h incubation with 40mug venom. Most spermatozoa suffered membrane wrinkling after 4 h incubation. However, incubation with 80 mug venom caused membrane fractures in most sperm heads after 1 h incubation. The extent and depth of these fractures were increased after 2-3 h incubation. After 4 h incubation, plasma membrane focal erosion of many spermatozoa heads was common. Incubation with 160 mg venom induced sperm head swollen plasma membranes after 1 h incubation. Ruptured and disintegrated membranes were seen after 2 h; lysis and removal of external surface of spermatozoa head plasma membranes were recorded after 3-4 h incubation. TEM indicated slightly swollen areas on the sperm head plasma membrane, but showed normal nuclei, acrosomes, and tail regions after 2 h incubation in 40 mug cobra venom. The swollen areas were accompanied by sperm head membrane disintegration as well as membrane irregularities and distortion of tail mitochondrial cristae after 3-4 h incubation. However, incubation with 80 mug venom showed focal areas of membrane lysis and discontinuity in the sperm heads and tails increasing with incubation time. Severe axoneme and tail longitudinal fiber degeneration and increased numbers of distorted mitochondrial cristae were also observed after 3-4 h incubation. Spermatozoa incubation with 160 mug venom increased severity of plasma membrane dissolution, disintegration, and rupture

  5. A pulsated weak-resonant-cavity laser diode with transient wavelength scanning and tracking for injection-locked RZ transmission.

    Lin, Gong-Ru; Chi, Yu-Chieh; Liao, Yu-Sheng; Kuo, Hao-Chung; Liao, Zhi-Wang; Wang, Hai-Lin; Lin, Gong-Cheng

    2012-06-18

    By spectrally slicing a single longitudinal-mode from a master weak-resonant-cavity Fabry-Perot laser diode with transient wavelength scanning and tracking functions, the broadened self-injection-locking of a slave weak-resonant-cavity Fabry-Perot laser diode is demonstrated to achieve bi-directional transmission in a 200-GHz array-waveguide-grating channelized dense-wavelength-division-multiplexing passive optical network system. Both the down- and up-stream slave weak-resonant-cavity Fabry-Perot laser diodes are non-return-to-zero modulated below threshold and coherently injection-locked to deliver the pulsed carrier for 25-km bi-directional 2.5 Gbits/s return-to-zero transmission. The master weak-resonant-cavity Fabry-Perot laser diode is gain-switched at near threshold condition and delivers an optical coherent pulse-train with its mode linewidth broadened from 0.2 to 0.8 nm by transient wavelength scanning, which facilitates the broadband injection-locking of the slave weak-resonant-cavity Fabry-Perot laser diodes with a threshold current reducing by 10 mA. Such a transient wavelength scanning induced spectral broadening greatly releases the limitation on wavelength injection-locking range required for the slave weak-resonant-cavity Fabry-Perot laser diode. The theoretical modeling and numerical simulation on the wavelength scanning and tracking effects of the master and slave weak-resonant-cavity Fabry-Perot laser diodes are performed. The receiving power sensitivity for back-to-back transmission at bit-error-rate transmission is less than 2 dB for all 16 channels. PMID:22714427

  6. Automated Transmission-Mode Scanning Electron Microscopy (tSEM) for Large Volume Analysis at Nanoscale Resolution

    Kuwajima, Masaaki; Mendenhall, John M.; Lindsey, Laurence F.; Harris, Kristen M.

    2013-01-01

    Transmission-mode scanning electron microscopy (tSEM) on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critic...

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

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

    2016-06-01

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

  8. A new approach to analysing HST spatial scans: the transmission spectrum of HD 209458b

    Tsiaras, A; Rocchetto, M; Varley, R; Morello, G; Tinetti, G

    2015-01-01

    The Wide Field Camera 3 (WFC3) on Hubble Space Telescope (HST) is currently one of the most popular instruments for observing exoplanetary atmospheres, especially with the use of the spatial scanning technique. An increasing number of exoplanets have been studied using this technique as it enables the observation of bright targets without saturating the sensitive detectors. In this work we present a new pipeline for analysing the data obtained with the spatial scanning technique, starting from the raw data provided by the instrument. In addition to commonly used correction techniques, we take into account the geometric distortions of the instrument, whose impact may become important when combined to the scanning process. Our approach can improve the photometric precision for existing data and also push further the limits of the spatial scanning technique, as it allows the analysis of even longer spatial scans. As an application of our method and pipeline, we present the results from a reanalysis of the spatia...

  9. Structural characterization of interfaces in epitaxial Fe/MgO/Fe magnetic tunnel junctions by transmission electron microscopy

    We present a detailed structural characterization of the interfaces in Fe/MgO/Fe layers grown by molecular-beam epitaxy using aberration-corrected transmission electron microscopy (TEM), scanning TEM, and electron energy-loss spectroscopy. When fabricated into magnetic tunnel junctions, these epitaxial devices exhibit large tunnel magnetoresistance ratios (e.g., 318% at 10 K), though still considerably lower than the values predicted theoretically. The reason for this discrepancy is being debated and has been attributed to the structure of, and defects at the interface, namely, the relative position of the atoms, interface oxidation, strain, and structural asymmetry of the interfaces. In this structural study, we observed that Fe is bound to O at the interfaces. The interfaces are semicoherent and mostly sharp with a minor degree of oxidation. A comparison of the two interfaces shows that the top MgO/Fe interface is rougher.

  10. Fast two-dimensional grid and transmission X-ray microscopy scanning methods for visualizing and characterizing protein crystals

    Wojdyla, Justyna Aleksandra; Panepucci, Ezequiel; Martiel, Isabelle; Ebner, Simon; Huang, Chia-Ying; Caffrey, Martin; Bunk, Oliver; Wang, Meitian

    2016-01-01

    A fast continuous grid scan protocol has been incorporated into the Swiss Light Source (SLS) data acquisition and analysis software suite on the macromolecular crystallography (MX) beamlines. Its combination with fast readout single-photon counting hybrid pixel array detectors (PILATUS and EIGER) allows for diffraction-based identification of crystal diffraction hotspots and the location and centering of membrane protein microcrystals in the lipid cubic phase (LCP) in in meso in situ serial crystallography plates and silicon nitride supports. Diffraction-based continuous grid scans with both still and oscillation images are supported. Examples that include a grid scan of a large (50 nl) LCP bolus and analysis of the resulting diffraction images are presented. Scanning transmission X-ray microscopy (STXM) complements and benefits from fast grid scanning. STXM has been demonstrated at the SLS beamline X06SA for near-zero-dose detection of protein crystals mounted on different types of sample supports at room and cryogenic temperatures. Flash-cooled crystals in nylon loops were successfully identified in differential and integrated phase images. Crystals of just 10 µm thickness were visible in integrated phase images using data collected with the EIGER detector. STXM offers a truly low-dose method for locating crystals on solid supports prior to diffraction data collection at both synchrotron microfocusing and free-electron laser X-ray facilities. PMID:27275141

  11. EVALUATION OF THE ULTRASTRUCTURE OF THE SMALL INTESTINE OF HIV INFECTED CHILDREN BY TRANSMISSION AND SCANNING ELECTRONIC MICROSCOPY

    Christiane Araujo Chaves LEITE

    2013-03-01

    Full Text Available Objectives To describe HIV children's small intestinal ultrastructural findings. Methods Descriptive, observational study of small intestine biopsies performed between August 1994 and May 1995 at São Paulo, SP, Brazil. This material pertained to 11 HIV infected children and was stored in a laboratory in paraffin blocks. Scanning and transmission electronic microscopy were used to view those intestine samples and ultrastructural findings were described by analyzing digitalized photos of this material. Ethical Committee approval was obtained. Results In most samples scanning microscopy showed various degrees of shortening and decreasing number of microvilli and also completes effacements in some areas. Derangement of the enterocytes was seen frequently and sometimes cells well defined borders limits seemed to be loosened. In some areas a mucous-fibrin like membrane with variable thickness and extension appeared to partially or totally coat the epithelial surface. Fat drops were present in the intestinal lumen in various samples and a bacterium morphologically resembling bacilli was seen in two occasions. Scanning microscopy confirmed transmission microscopy microvilli findings and also showed little “tufts” of those structures. In addition, it showed an increased number of vacuoles and multivesicular bodies inside various enterocytes, an increased presence of intraepithelial lymphocytes, mitochondrial vacuolization and basement membrane enlargement in the majority of samples analyzed. However, some samples exhibited normal aspect. Conclusions Our study showed the common occurrence of various important intestinal ultrastructural alterations with variable degrees among HIV infected children, some of them in our knowledge not described before.

  12. Determination of the cork bark porosity through the gamma ray transmission technology and electronic scanning microscopy image analysis

    This work applies the gamma transmission techniques (GTR) and imaging by scanning electron microscopy (SEM) for determination of porosity in the sparkling wine bottle corks. The gamma transmission experimental apparatus consists of a micrometric table (ZX) of sample movement automated, a Am-241 source (59,53 keV, 100 mCi), lead collimators, sample-holder, Na I(Tl) detector and appropriated electronics. For the microscopic images an FEI (Quanta 200), electronic microscope with associated electronics was used, and the image analysis was performed with IMAGO software. The average porosity for 22 samples analysed by GTR was of φ=58 +- 4.6 percent. By the imaging technique the found average porosity was φ=60.0 +- 6.2 percent. (author)

  13. A new bend magnet beam line for scanning transmission x-ray microscopy at the Advanced Light Source

    Warwick, Tony; Ade, Harald; Kilcoyne, A.L. David; Kritscher, Michael; Tylisczcak, Tolek; Fakra, Sirine; Hitchcock, Adam P.; Hitchcock, Peter; Padmore, Howard A.

    2001-12-12

    The high brightness of the bend magnets at the Advanced Light Source has been exploited to illuminate a Scanning Transmission X-ray Microscope (STXM). This is the first diffraction-limited scanning x-ray microscope to operate with useful count rate on a synchrotron bend magnet source. A simple, dedicated beam line has been built covering the range of photon energy from 250 eV to 600 eV. Ease of use and operational availability are radically improved compared to previous installations using undulator beams. This facility provides radiation for C 1s, N 1s and O 1s near edge x-ray absorption spectro-microscopy with a spectral resolution up to about 1:5000 and with STXM count rates in excess of 1 MHz.

  14. Characterizing deformed ultrafine-grained and nanocrystalline materials using transmission Kikuchi diffraction in a scanning electron microscope

    Graphical abstract: -- Abstract: The recent development of transmission Kikuchi diffraction (TKD) in a scanning electron microscope enables fast, automated orientation mapping of electron transparent samples using standard electron backscatter diffraction (EBSD) hardware. TKD in a scanning electron microscope has significantly better spatial resolution than conventional EBSD, enabling routine characterization of nanocrystalline materials and allowing effective measurement of samples that have undergone severe plastic deformation. Combining TKD with energy dispersive X-ray spectroscopy (EDS) provides complementary chemical information, while a standard forescatter detector system below the EBSD detector can be used to generate dark field and oriented dark field images. Here we illustrate the application of this exciting new approach to a range of deformed, ultrafine grained and nanocrystalline samples, including duplex stainless steel, nanocrystalline copper and highly deformed titanium and nickel–cobalt. The results show that TKD combined with EDS is a highly effective and widely accessible tool for measuring key microstructural parameters at resolutions that are inaccessible using conventional EBSD

  15. Largely defocused probe scanning transmission electron microscopy for imaging local modulation of strain field in a hetero interface

    Kim, Suhyun, E-mail: u98kim@surface.phys.titech.ac.jp; Jung, Younheum; Kim, Joong Jung; Lee, Sunyoung; Lee, Haebum [Memory Analysis Science and Engineering Group, Samsung Electronics, San #16 Hwasung-City, Gyeonggi-Do 445-701 (Korea, Republic of); Oshima, Yoshifumi [School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Nomi, Ishikawa 923-1292 (Japan)

    2014-10-13

    We present an innovative method for characterizing the strain field in three dimensions in a hetero interface. Largely defocused probe scanning transmission electron microscopy (LDP-STEM) was employed for imaging the inhomogeneous strain field in a germanium (Ge) layer deposited on a silicon (Si) substrate. In the LDP-STEM image, Ge-atomic columns that are relaxed or strained to the Si substrate in the Si/Ge hetero interface were observed to be distinguishable, allowing for the qualitative characterization of the coherency of the crystal growth. Our results revealed that the strain field is locally modulated along the in-plane direction in the Si/Ge hetero interface.

  16. Probing the electronic structure of graphene sheets with various thicknesses by scanning transmission X-ray microscopy

    Bai, Lili; Liu, Jinyin; Zhao, Guanqi; Gao, Jing; Sun, Xuhui, E-mail: xhsun@suda.edu.cn, E-mail: jzhong@suda.edu.cn; Zhong, Jun, E-mail: xhsun@suda.edu.cn, E-mail: jzhong@suda.edu.cn [Soochow University-Western University Centre for Synchrotron Radiation Research, Institute of Functional Nano and Soft Materials Laboratory (FUNSOM) and Collaborative Innovation Center of Suzhou Nano Science and Technology, Soochow University, Suzhou 215123 (China)

    2013-12-16

    The electronic structure of an aggregation of graphene sheets with various thicknesses was probed by scanning transmission X-ray microscopy. A uniform oxidation of the graphene sheets in the flat area was observed regardless of the thickness, while in the folded area the result could be strongly affected by the geometry. Moreover, thick parts of the aggregation showed strong angle-dependence to the incident X-ray, while thin parts showed less angle-dependence, which might be related to the surface wrinkles and ripples. The electronic structure differences due to the geometry and thickness suggest a complicated situation in the aggregation of graphene sheets.

  17. Energy dispersive X-ray analysis on an absolute scale in scanning transmission electron microscopy

    We demonstrate absolute scale agreement between the number of X-ray counts in energy dispersive X-ray spectroscopy using an atomic-scale coherent electron probe and first-principles simulations. Scan-averaged spectra were collected across a range of thicknesses with precisely determined and controlled microscope parameters. Ionization cross-sections were calculated using the quantum excitation of phonons model, incorporating dynamical (multiple) electron scattering, which is seen to be important even for very thin specimens. - Highlights: • Scan-averaged energy dispersive X-ray (EDX) spectra are recorded in STEM. • Experimental and simulated EDX signals are shown to agree on an absolute scale. • Two independent methods are used for accurate thickness determination. • Probe channelling must be taken into account, even for very thin specimens. • Channelling effects are minimized for large probe-forming convergence angles

  18. Energy dispersive X-ray analysis on an absolute scale in scanning transmission electron microscopy

    Chen, Z. [School of Physics and Astronomy, Monash University, Clayton, Victoria 3800 (Australia); D' Alfonso, A.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Weyland, M. [Monash Centre for Electron Microscopy, Monash University, Clayton, Victoria 3800 (Australia); Department of Materials Science and Engineering, Monash University, Clayton, Victoria 3800 (Australia); Taplin, D.J. [School of Physics and Astronomy, Monash University, Clayton, Victoria 3800 (Australia); Allen, L.J. [School of Physics, University of Melbourne, Parkville, Victoria 3010 (Australia); Findlay, S.D., E-mail: scott.findlay@monash.edu [School of Physics and Astronomy, Monash University, Clayton, Victoria 3800 (Australia)

    2015-10-15

    We demonstrate absolute scale agreement between the number of X-ray counts in energy dispersive X-ray spectroscopy using an atomic-scale coherent electron probe and first-principles simulations. Scan-averaged spectra were collected across a range of thicknesses with precisely determined and controlled microscope parameters. Ionization cross-sections were calculated using the quantum excitation of phonons model, incorporating dynamical (multiple) electron scattering, which is seen to be important even for very thin specimens. - Highlights: • Scan-averaged energy dispersive X-ray (EDX) spectra are recorded in STEM. • Experimental and simulated EDX signals are shown to agree on an absolute scale. • Two independent methods are used for accurate thickness determination. • Probe channelling must be taken into account, even for very thin specimens. • Channelling effects are minimized for large probe-forming convergence angles.

  19. Scanning transmission ion microscopy (STIM) with a 3 MeV proton cyclotron beam

    Maanen, I.F. van [Technische Univ., Eindhoven (Netherlands). Cyclotron Lab.; Mutsaers, P.H.A. [Technische Univ., Eindhoven (Netherlands). Cyclotron Lab.; Verhoef, B.A.W. [Technische Univ., Eindhoven (Netherlands). Cyclotron Lab.; Voigt, M.J.A. de [Technische Univ., Eindhoven (Netherlands). Cyclotron Lab.

    1996-06-01

    A method is developed to optimize the lateral resolution of a scanning proton microprobe using a 3 MeV cyclotron beam. The most important part of the method is the optimization of an asymmetrical quadrupole quadruplet, based on second-order relationships between diaphragm widths and the full width of the spot. A STIM example is presented of cellular structures of rat-heart tissue. (orig.).

  20. Scanning transmission ion microscopy (STIM) with a 3 MeV proton cyclotron beam

    A method is developed to optimize the lateral resolution of a scanning proton microprobe using a 3 MeV cyclotron beam. The most important part of the method is the optimization of an asymmetrical quadrupole quadruplet, based on second-order relationships between diaphragm widths and the full width of the spot. A STIM example is presented of cellular structures of rat-heart tissue. (orig.)

  1. Analysis of self-organized In(Ga)As quantum structures with the scanning transmission electron microscope

    Aim of this thesis was to apply the analytical methods of the scanning transmission electron microscopy to the study of self-organized In(Ga)As quantum structures. With the imaging methods Z contrast and bright field (position resolutions in the subnanometer range) and especially with the possibilities of the quantitative chemical EELS analysis of the scanning transmission electron microscope (STEM) fundamental questions concerning morphology and chemical properties of self-organized quantum structures should be answered. By the high position resolution of the STEM among others essentail morphological and structural parameters in the growth behaviour of ''dot in a well'' (DWell) structures and of vertically correlated quantum dots (QDs) could be analyzed. For the optimization of DWell structures samples were studied, the nominal InAs-QD growth position was directedly varied within the embedding InGaAs quantum wells. The STEM offers in connection with the EELS method a large potential for the chemical analysis of quantum structures. Studied was a sample series of self-organized InGaAs/GaAs structures on GaAs substrate, the stress of which was changed by varying the Ga content of the INGaAs material between 2.4 % and 4.3 %

  2. Automated transmission-mode scanning electron microscopy (tSEM for large volume analysis at nanoscale resolution.

    Masaaki Kuwajima

    Full Text Available Transmission-mode scanning electron microscopy (tSEM on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critical for neuronal function. Individual image fields from the tSEM system were up to 4,295 µm(2 (65.54 µm per side at 2 nm pixel size, contrasting with image fields from a modern transmission electron microscope (TEM system, which were only 66.59 µm(2 (8.160 µm per side at the same pixel size. The tSEM produced outstanding images and had reduced distortion and drift relative to TEM. Automated stage and scan control in tSEM easily provided unattended serial section imaging and montaging. Lens and scan properties on both TEM and SEM platforms revealed no significant nonlinear distortions within a central field of ∼100 µm(2 and produced near-perfect image registration across serial sections using the computational elastic alignment tool in Fiji/TrakEM2 software, and reliable geometric measurements from RECONSTRUCT™ or Fiji/TrakEM2 software. Axial resolution limits the analysis of small structures contained within a section (∼45 nm. Since this new tSEM is non-destructive, objects within a section can be explored at finer axial resolution in TEM tomography with current methods. Future development of tSEM tomography promises thinner axial resolution producing nearly isotropic voxels and should provide within-section analyses of structures without changing platforms. Brain was the test system given our interest in synaptic connectivity and plasticity; however, the new tSEM system is readily applicable to other biological systems.

  3. Automated transmission-mode scanning electron microscopy (tSEM) for large volume analysis at nanoscale resolution.

    Kuwajima, Masaaki; Mendenhall, John M; Lindsey, Laurence F; Harris, Kristen M

    2013-01-01

    Transmission-mode scanning electron microscopy (tSEM) on a field emission SEM platform was developed for efficient and cost-effective imaging of circuit-scale volumes from brain at nanoscale resolution. Image area was maximized while optimizing the resolution and dynamic range necessary for discriminating key subcellular structures, such as small axonal, dendritic and glial processes, synapses, smooth endoplasmic reticulum, vesicles, microtubules, polyribosomes, and endosomes which are critical for neuronal function. Individual image fields from the tSEM system were up to 4,295 µm(2) (65.54 µm per side) at 2 nm pixel size, contrasting with image fields from a modern transmission electron microscope (TEM) system, which were only 66.59 µm(2) (8.160 µm per side) at the same pixel size. The tSEM produced outstanding images and had reduced distortion and drift relative to TEM. Automated stage and scan control in tSEM easily provided unattended serial section imaging and montaging. Lens and scan properties on both TEM and SEM platforms revealed no significant nonlinear distortions within a central field of ∼100 µm(2) and produced near-perfect image registration across serial sections using the computational elastic alignment tool in Fiji/TrakEM2 software, and reliable geometric measurements from RECONSTRUCT™ or Fiji/TrakEM2 software. Axial resolution limits the analysis of small structures contained within a section (∼45 nm). Since this new tSEM is non-destructive, objects within a section can be explored at finer axial resolution in TEM tomography with current methods. Future development of tSEM tomography promises thinner axial resolution producing nearly isotropic voxels and should provide within-section analyses of structures without changing platforms. Brain was the test system given our interest in synaptic connectivity and plasticity; however, the new tSEM system is readily applicable to other biological systems. PMID:23555711

  4. Lung scan accuracy and precision in the diagnosis of pulmonary embolism by transmission, perfusion and ventilation procedures

    Although there is controversy over the value of radionuclide lung scans in the diagnosis of pulmonary thrombo-embolism, the procedure remains non-invasive, accurate and precise given proper methodological and interpretive criteria. Reviewing 959 procedures from the past decade in 539 patients, including 23 autopsies (correctly diagnosed antemortem), 93 emergencies (67 in 1973; 26 since), 8 pulmonary angiograms, 649 (8 view) perfusion studies with transmission view and 'first pass' flow using 99mTc-Macroparticles (MAA or HAM), 257 ventilation studies using 133-Xenen, 53 'aerosol' studies (either 'wet' or 'dry' radioinhalant), 113 computer analyses and 13 'closing volumes' (as well estimated by imaging as standard techniques (p<0.05)); a sensitivity of 92 percent, a specificity of 96 percent, an efficiency of 96 percent with a probability of disease with a positive study of 90 percent and a likelihood of disease with a negative study of 2 percent were found. Peripheral thrombosis and positive lung scans for pulmonary embolism occurred frequently. Based on these data, the lung scan properly carried out is reliable especially to exclude pulmonary embolism, frequently rendering invasive procedures unnecessary. (Author)

  5. A new Scanning Transmission X-ray Microscope at the ALS for operation up to 2500eV

    We report on the design and construction of a higher energy Scanning Transmission X-ray Microscope on a new bend magnet beam line at the Advanced Light Source. Previously we have operated such an instrument on a bend magnet for C, N and O 1s NEXAFS spectroscopy. The new instrument will have similar performance at higher energies up to and including the S 1s edge at 2472eV. A new microscope configuration is planned. A more open geometry will allow a fluorescence detector to count emitted photons from the front surface of the sample. There will be a capability for zone plate scanning in addition to the more conventional sample scanning mode. This will add the capability for imaging a massive sample at high resolution over a limited field of view, so that heavy reaction cells may be used to study processes in-situ, exploiting the longer photon attenuation length and the longer zone plate working distances available at higher photon energy. The energy range will extend down to include the C1s edge at 300eV, to allow high energy NEXAFS microscopic studies to correlate with the imaging of organics in the same sample region of interest.

  6. High resolution scanning transmission electron microscopy (HR STEM) analysis of re-deposited layer on ASDEX Upgrade tile

    Rasinski, M., E-mail: mrasin@o2.pl [Warsaw University of Technology, Faculty of Material Science and Engineering, Woloska 141, 02-507 Warsaw (Poland); Fortuna-Zalesna, E. [Warsaw University of Technology, Faculty of Material Science and Engineering, Woloska 141, 02-507 Warsaw (Poland); Mayer, M.; Neu, R. [Max-Planck-Institut fuer Plasmaphysik, Euratom Association, Boltzmannstrasse 2, D-85748 Garching (Germany); Plocinski, T.; Lewandowska, M.; Kurzydlowski, K.J. [Warsaw University of Technology, Faculty of Material Science and Engineering, Woloska 141, 02-507 Warsaw (Poland)

    2011-10-15

    Erosion and re-deposition of plasma-facing components (PFCs) is one of the most important issues in fusion devices and as such it is an area of interest for many research groups. However, the structure and composition of re-deposited layers as well as the mechanism and condition of their formation are not yet fully described and understood. In the present study, the structure and the composition of co-deposited layers, which developed at the outer divertor strike point tiles in ASDEX Upgrade during the 2009 campaign were examined. High resolution scanning transmission electron microscopy (HRSTEM) combined with energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) have been used to identify deposits composition and morphology. Tungsten foam like structure and co-deposits rich in tungsten, oxygen, carbon, boron and nitrogen were observed.

  7. High resolution scanning transmission electron microscopy (HR STEM) analysis of re-deposited layer on ASDEX Upgrade tile

    Erosion and re-deposition of plasma-facing components (PFCs) is one of the most important issues in fusion devices and as such it is an area of interest for many research groups. However, the structure and composition of re-deposited layers as well as the mechanism and condition of their formation are not yet fully described and understood. In the present study, the structure and the composition of co-deposited layers, which developed at the outer divertor strike point tiles in ASDEX Upgrade during the 2009 campaign were examined. High resolution scanning transmission electron microscopy (HRSTEM) combined with energy-dispersive X-ray spectroscopy (EDS) and electron energy loss spectroscopy (EELS) have been used to identify deposits composition and morphology. Tungsten foam like structure and co-deposits rich in tungsten, oxygen, carbon, boron and nitrogen were observed.

  8. Morphology of gills of the seawater fish Cathorops spixii (Agassiz (Ariidae by scanning and transmission electron microscopy

    Daura R. Eiras-Stofella

    2002-12-01

    Full Text Available Gills of the seawater fish Cathorops spixii (Agassiz, 1829 were submitted to routine processing for observation in scanning and transmission electron microscopy. The wrinkled surface of the gill filaments showed well-defined cellular ultrastructures. Microridges on cellular surface were projected over all gill structures, including respiratory lamellae. Chloride cells were usually at primary lamellae. Some rodlet cells were found. Mucous secretory cells were uncommon at all parts of the gill arches. The pharyngeal region of the gill arches showed a lot of taste buds but no spines. There were small and strong rakers. Such morphology is indicative of fishes that swallow small food but do not have filtering habits. At the ultrastructural level the gills of C. spixii presented the typical morphological pattern of Teleostei fishes.

  9. Quantitative atom column position analysis at the incommensurate interfaces of a (PbS)1.14NbS2 misfit layered compound with aberration-corrected HRTEM

    Aberration-corrected HRTEM is applied to explore the potential of NCSI contrast imaging to quantitatively analyse the complex atomic structure of misfit layered compounds and their incommensurate interfaces. Using the (PbS)1.14NbS2 misfit layered compound as a model system it is shown that atom column position analyses at the incommensurate interfaces can be performed with precisions reaching a statistical accuracy of ±6 pm. The procedure adopted for these studies compares experimental images taken from compound regions free of defects and interface modulations with a structure model derived from XRD experiments and with multi-slice image simulations for the corresponding NCSI contrast conditions used. The high precision achievable in such experiments is confirmed by a detailed quantitative analysis of the atom column positions at the incommensurate interfaces, proving a tetragonal distortion of the monochalcogenide sublattice. -- Research Highlights: → Quantitative aberration-corrected HRTEM analysis of atomic column positions in (PbS)1.14NbS2 misfit layered compound reveals tetragonal distortion of the PbS subsystem. → Detailed comparison of multi-slice simulations with the experimental NCSI contrast condition imaging results lead to a high precision (better than 10 pm) for determining the positions of atoms. → Precision in gaining information of local structure at atomic scale is demonstrated, which may not be accessible by means of X-ray and neutron diffraction analysis.

  10. Whole-cell imaging of the budding yeast Saccharomyces cerevisiae by high-voltage scanning transmission electron tomography

    Electron tomography using a high-voltage electron microscope (HVEM) provides three-dimensional information about cellular components in sections thicker than 1 μm, although in bright-field mode image degradation caused by multiple inelastic scattering of transmitted electrons limit the attainable resolution. Scanning transmission electron microscopy (STEM) is believed to give enhanced contrast and resolution compared to conventional transmission electron microscopy (CTEM). Samples up to 1 μm in thickness have been analyzed with an intermediate-voltage electron microscope because inelastic scattering is not a critical limitation, and probe broadening can be minimized. Here, we employed STEM at 1 MeV high-voltage to extend the useful specimen thickness for electron tomography, which we demonstrate by a seamless tomographic reconstruction of a whole, budding Saccharomyces cerevisiae yeast cell, which is ∼3 μm in thickness. High-voltage STEM tomography, especially in the bright-field mode, demonstrated sufficiently enhanced contrast and intensity, compared to CTEM tomography, to permit segmentation of major organelles in the whole cell. STEM imaging also reduced specimen shrinkage during tilt-series acquisition. The fidelity of structural preservation was limited by cytoplasmic extraction, and the spatial resolution was limited by the relatively large convergence angle of the scanning probe. However, the new technique has potential to solve longstanding problems of image blurring in biological specimens beyond 1 μm in thickness, and may facilitate new research in cellular structural biology. - Highlights: • High voltage TEM and STEM tomography were compared to visualize whole yeast cells. • 1-MeV STEM-BF tomography had significant improvements in image contrast and SNR. • 1-MeV STEM tomography showed less specimen shrinkage than the TEM tomography. • KMnO4 post-treatment permitted segmenting the major cellular components

  11. Whole-cell imaging of the budding yeast Saccharomyces cerevisiae by high-voltage scanning transmission electron tomography

    Murata, Kazuyoshi, E-mail: kazum@nips.ac.jp [National Institute for Physiological Sciences, Okazaki, Aichi 444-8585 (Japan); Esaki, Masatoshi; Ogura, Teru [Institute of Molecular Embryology and Genetics, Kumamoto University, Kumamoto 860-0811 (Japan); Arai, Shigeo; Yamamoto, Yuta; Tanaka, Nobuo [Ecotopia Science Institute, Nagoya University, Nagoya, Aichi 464-8603 (Japan)

    2014-11-15

    Electron tomography using a high-voltage electron microscope (HVEM) provides three-dimensional information about cellular components in sections thicker than 1 μm, although in bright-field mode image degradation caused by multiple inelastic scattering of transmitted electrons limit the attainable resolution. Scanning transmission electron microscopy (STEM) is believed to give enhanced contrast and resolution compared to conventional transmission electron microscopy (CTEM). Samples up to 1 μm in thickness have been analyzed with an intermediate-voltage electron microscope because inelastic scattering is not a critical limitation, and probe broadening can be minimized. Here, we employed STEM at 1 MeV high-voltage to extend the useful specimen thickness for electron tomography, which we demonstrate by a seamless tomographic reconstruction of a whole, budding Saccharomyces cerevisiae yeast cell, which is ∼3 μm in thickness. High-voltage STEM tomography, especially in the bright-field mode, demonstrated sufficiently enhanced contrast and intensity, compared to CTEM tomography, to permit segmentation of major organelles in the whole cell. STEM imaging also reduced specimen shrinkage during tilt-series acquisition. The fidelity of structural preservation was limited by cytoplasmic extraction, and the spatial resolution was limited by the relatively large convergence angle of the scanning probe. However, the new technique has potential to solve longstanding problems of image blurring in biological specimens beyond 1 μm in thickness, and may facilitate new research in cellular structural biology. - Highlights: • High voltage TEM and STEM tomography were compared to visualize whole yeast cells. • 1-MeV STEM-BF tomography had significant improvements in image contrast and SNR. • 1-MeV STEM tomography showed less specimen shrinkage than the TEM tomography. • KMnO{sub 4} post-treatment permitted segmenting the major cellular components.

  12. Impulse radio ultra wideband wireless transmission of dopamine concentration levels recorded by fast-scan cyclic voltammetry.

    Ebrazeh, Ali; Bozorgzadeh, Bardia; Mohseni, Pedram

    2015-08-01

    This paper demonstrates the feasibility of utilizing impulse radio ultra wideband (IR-UWB) signaling technique for reliable, wireless transmission of dopamine concentration levels recorded by fast-scan cyclic voltammetry (FSCV) at a carbon-fiber microelectrode (CFM) to address the problem of elevated data rates in high-channel-count neurochemical monitoring. Utilizing an FSCV-sensing chip fabricated in AMS 0.35μm 2P/4M CMOS, a 3-5-GHz, IR-UWB transceiver (TRX) chip fabricated in TSMC 90nm 1P/9M RF CMOS, and two off-chip, miniature, UWB antennae, wireless transfer of pseudo-random binary sequence (PRBS) data at 50Mbps over a distance of wireless transmission of dopamine concentration levels prerecorded with FSCV at a CFM during flow injection analysis (FIA) is also demonstrated with transmitter (TX) power dissipation of only ~4.4μW from 1.2V, representing two orders of magnitude reduction in TX power consumption compared to that of a conventional frequency-shift-keyed (FSK) link operating at ~433MHz. PMID:26737929

  13. Atomically resolved FeSe/SrTiO3(001) interface structure by scanning transmission electron microscopy

    Li, Fangsen; Zhang, Qinghua; Tang, Chenjia; Liu, Chong; Shi, Jinan; Nie, CaiNa; Zhou, Guanyu; Li, Zheng; Zhang, Wenhao; Song, Can-Li; He, Ke; Ji, Shuaihua; Zhang, Shengbai; Gu, Lin; Wang, Lili; Ma, Xu-Cun; Xue, Qi-Kun

    2016-06-01

    Interface-enhanced high-temperature superconductivity in one unit-cell FeSe films on SrTiO3(001) (STO) substrate has recently attracted much attention in condensed matter physics and material science. By combined in situ scanning tunneling microscopy/spectroscopy and ex situ scanning transmission electron microscopy studies, we report on atomically resolved structure including both lattice constants and actual atomic positions of the FeSe/STO interface under both non-superconducting and superconducting states. We observed TiO2 double layers and significant atomic displacements in the top two layers of STO, lattice compression of the Se-Fe-Se triple layer, and relative shift between bottom Se and topmost Ti atoms. By imaging the interface structures under various superconducting states, we unveil a close correlation between interface structure and superconductivity. Our atomic-scale identification of FeSe/STO interface structure provides insight on investigating the pairing mechanism of this interface-enhanced high-temperature superconducting system.

  14. EPS composition and calcification potential of tufa-dominating cyanobacteria investigated by Scanning Transmission X-ray Microscopy (STXM) and Laser Scanning Microscopy (LSM)

    Zippel, Barbara; Dynes, James J.; Obst, Martin; Lawrence, John R.; Neu, Thomas R.

    2010-05-01

    Tufa deposits in freshwater habitats are the result of calcium carbonate precipitation within interfacial microbial ecosystems. Calcite precipitation is influenced by the saturation index and the occurrence of extracellular polymeric substances (EPS) which are produced by a variety of microorganisms. In theory, the first important step of biologically induced calcification processes is the adsorption of calcium ions by extracellular polymeric substances (EPS) produced by cyanobacteria. In the present study we take advantage of Laser Scanning Microscopy (LSM) and combine it with Synchrotron imaging using Scanning Transmission X-ray Microscopy (STXM). STXM represents a technique that allows simultaneous analysis of inorganic and organic constituents as a scale of 50 nm. By means of STXM it is possible to differentiate between calcium carbonate phases at the Ca L-edge. Furthermore, STXM has also been used at the C K-edge to map the major biomolecules (proteins, lipids, and polysaccharides). The purpose of this study is to find out if there are differences in calcium adsorption depending on specific composition of the EPS produced by filamentous cyanobacteria isolated from a German hard water creek (Westerhöfer Bach, Harz Mountains). The goal was to elucidate the potential of biofilms constituents, including microbial cell surfaces as well as extracellular polymeric substances, in triggering the formation of calcium carbonate in tufa systems. For this purpose three filamentous cyanobacteria (Pseudanabaena sp., Leptolyngbya sp. and Nostoc sp.) were cultivated in creek-adapted as well as standard media (BG11) on polycarbonate slides. In situ EPS composition was detected by means of fluorescence lectin-binding approach (FLBA) using 23 commercially available lectins with different specificities for mono- and disaccharides and amino sugars. For CaCO3 nucleation experiments cyanobacterial biofilms grown on polycarbonate slides were deposited in NaHCO3/CaCl2 solutions

  15. Imaging and elemental mapping of biological specimens with a dual-EDS dedicated scanning transmission electron microscope

    A dedicated analytical scanning transmission electron microscope (STEM) with dual energy dispersive spectroscopy (EDS) detectors has been designed for complementary high performance imaging as well as high sensitivity elemental analysis and mapping of biological structures. The performance of this new design, based on a Hitachi HD-2300A model, was evaluated using a variety of biological specimens. With three imaging detectors, both the surface and internal structure of cells can be examined simultaneously. The whole-cell elemental mapping, especially of heavier metal species that have low cross-section for electron energy loss spectroscopy (EELS), can be faithfully obtained. Optimization of STEM imaging conditions is applied to thick sections as well as thin sections of biological cells under low-dose conditions at room and cryogenic temperatures. Such multimodal capabilities applied to soft/biological structures usher a new era for analytical studies in biological systems. - Highlights: ► Applications of STEM in characterization of biological samples are demonstrated. ► Elemental analyses are performed by dual EDS and EELS. ► Both the surface and internal structure of cells can be studied simultaneously. ► The imaging contrast in low-dose cryo-STEM has been analyzed

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

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

    2015-04-15

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

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

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

  18. Scanning transmission electron microscopic study of molluscan hemocyanins in various aggregation states: comparison with light scattering molecular weights.

    Hamilton, M G; Herskovits, T T; Furcinitti, P S; Wall, J S

    1989-12-01

    The masses of individual particles of the hemocyanins of six members of two molluscan classes, Polyplacophora and Gastropoda, have been determined by scanning transmission electron microscopy (STEM) of unstained specimens dried from the frozen state. The decameric hemocyanins of two chitons, Mopalia muscosa and Stenoplax conspicua, had masses of 4.20 +/- 0.18 and 4.47 +/- 0.56 MDa, respectively; the didecameric hemocyanins of two gastropods, Fasciolaria tulipa and Pleuroploca gigantea, had masses of 8.67 +/- 0.44 and 8.96 +/- 0.39 MDa, respectively; and the tridecameric hemocyanin of Lunatia heros had a mass of 13.50 +/- 0.44 MDa. The STEM values were in close agreement with those obtained by light scattering measurements of the same samples in solution. For Busycon contrarium, a gastropod with a multidecameric hemocyanin, nine size classes from didecamers to decadecamers with masses that corresponded to multiples of a basic decamer (4.4 MDa) were detected. The appearance of unstained specimens of the cylindrical particles differs from negatively stained specimens. Viewed end-on the cylinders show no internal structure, but in well-preserved specimens cavities are apparent in the side views of the cylinders that resemble those seen in negatively stained specimens. Although they lack the characteristic "tiered" appearance, the number of decameric units can be counted and their arrangement within the particle seen. PMID:2634708

  19. Design and Performance of a TES X-ray Microcalorimeter Array for Energy Dispersive Spectroscopy on Scanning Transmission Electron Microscope

    Muramatsu, Haruka; Nagayoshi, K.; Hayashi, T.; Sakai, K.; Yamamoto, R.; Mitsuda, K.; Yamasaki, N. Y.; Maehata, K.; Hara, T.

    2016-07-01

    We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate (>20 kcps), wide energy band (0.5-15 keV) and good energy resolution (<10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an 8 × 8 format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 \\upmu s which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed.

  20. Imaging and elemental mapping of biological specimens with a dual-EDS dedicated scanning transmission electron microscope

    Wu, J.S., E-mail: jinsong-wu@northwestern.edu [Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, Evanston, IL 60208 (United States); Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Kim, A.M. [Department of Obstetrics and Gynecology, Feinberg School of Medicine, Northwestern University, Chicago, IL 60611 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Bleher, R. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Myers, B.D. [Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, Evanston, IL 60208 (United States); Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Marvin, R.G. [Department of Chemistry, Northwestern University, Evanston, IL 60208 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Inada, H.; Nakamura, K. [Hitachi High-Technologies Corporation, Ibaraki 312-8504 (Japan); Zhang, X.F. [Hitachi High Technologies America, Inc., 5960 Inglewood Drive, Pleasanton, California 94588 (United States); Roth, E. [Department of Materials Science and Engineering, Northwestern University, Evanston, IL 60208 (United States); Chemistry of Life Processes Institute, Northwestern University, Evanston, IL 60208 (United States); Li, S.Y. [Northwestern University Atomic and Nanoscale Characterization Experimental (NUANCE) Center, Northwestern University, Evanston, IL 60208 (United States); and others

    2013-05-15

    A dedicated analytical scanning transmission electron microscope (STEM) with dual energy dispersive spectroscopy (EDS) detectors has been designed for complementary high performance imaging as well as high sensitivity elemental analysis and mapping of biological structures. The performance of this new design, based on a Hitachi HD-2300A model, was evaluated using a variety of biological specimens. With three imaging detectors, both the surface and internal structure of cells can be examined simultaneously. The whole-cell elemental mapping, especially of heavier metal species that have low cross-section for electron energy loss spectroscopy (EELS), can be faithfully obtained. Optimization of STEM imaging conditions is applied to thick sections as well as thin sections of biological cells under low-dose conditions at room and cryogenic temperatures. Such multimodal capabilities applied to soft/biological structures usher a new era for analytical studies in biological systems. - Highlights: ► Applications of STEM in characterization of biological samples are demonstrated. ► Elemental analyses are performed by dual EDS and EELS. ► Both the surface and internal structure of cells can be studied simultaneously. ► The imaging contrast in low-dose cryo-STEM has been analyzed.

  1. Structural characterization of annatto seeds (Bixa orellana) by transmission and scanning electron microscopy submitted to gamma radiation for dormancy break

    The annatto (Bixa orellana) is the only species of the Bixaceae family. From the seeds an important food colorant is obtained, bixin, for the industry and domestic use. More recently studies have focused more extensively in medicinal purpose of the species. Due to structural and physiologic characteristics, the seeds have low germination rate, around 30 %. The irradiation of seeds with gamma radiation can promote the increase and/or acceleration of germination, better plant development and productivity, among other aspects. The radiation doses used for this purpose should not cause genetic modifications in the organism, hence experimentation is needed to define the appropriate doses. Absence of research done annatto related to the use of the irradiation aiming at the increase of germination rates lead to the structural characterization of the annatto seeds submitted to gamma radiation through transmission (TEM) and scanning electron microscopy (SEM). The objective of this study was to verify the effect of radiation on the seeds structures during the process of dormancy break. Dry seeds and seeds immersed in distilled water for 24 hours were submitted to gamma radiation from source of Co60 type Gammacell-220 at CENA/USP, at doses 100 Gy. After irradiation the seeds were processed for TEM and SEM. Preliminary results, showed structural modifications in the seeds. (author)

  2. Design and Performance of a TES X-ray Microcalorimeter Array for Energy Dispersive Spectroscopy on Scanning Transmission Electron Microscope

    Muramatsu, Haruka; Nagayoshi, K.; Hayashi, T.; Sakai, K.; Yamamoto, R.; Mitsuda, K.; Yamasaki, N. Y.; Maehata, K.; Hara, T.

    2016-02-01

    We discuss the design and performance of a transition edge sensor (TES) X-ray microcalorimeter array for scanning transmission electron microscope (STEM)-energy dispersive X-ray spectroscopy (EDS). The TES X-ray microcalorimeter has better energy resolution compared to conventional silicon drift detector and STEM-EDS utilizing a TES detector makes it possible to map the distribution of elements on a specimen in addition to analyze the composition. The requirement for a TES detector is a high counting rate (> 20 kcps), wide energy band (0.5-15 keV) and good energy resolution (< 10 eV) full width at half maximum. The major improvement of this development is to increase the maximum counting rate. In order to accommodate the high counting rate, we adopted an 8 × 8 format, 64-pixel array and common biasing scheme for the readout method. We did all design and fabrication of the device in house. With the device we have fabricated most recently, the pulse decay time is 40 \\upmu s which is expected to achieve 50 kcps. For a single pixel, the measured energy resolution was 7.8 eV at 5.9 keV. This device satisfies the requirements of counting rate and energy resolution, although several issues remain where the performance must be confirmed.

  3. A Transition Edge Sensor Microcalorimeter System for the Energy Dispersive Spectroscopy Performed on a Scanning-Transmission Electron Microscope

    Maehata, K.; Hara, T.; Mitsuda, K.; Hidaka, M.; Tanaka, K.; Yamanaka, Y.

    2015-11-01

    We are conducting the development of a transition edge sensor (TES) microcalorimeter system for energy-dispersive X-ray spectroscopy (EDS), performed using a scanning-transmission electron microscope (STEM). The operating temperature of the TES microcalorimeter was maintained using a compact dry 3 He-4 He dilution refrigerator. This was pre-cooled by a remote helium cooling loop system and a Gifford-McMahon cooler. These conditions allowed for high-resolution STEM imaging to be achieved. A single-pixel TES microcalorimeter with a polycapillary optic was selected to demonstrate the analytical operation of the EDS system in the STEM. For a Ti-It-Pt sample, an X-ray energy resolution of 8.6 eV full-width at half maximum (FWHM) was obtained at Ir M_{α 1} , Pt M_{α 1} , and Ir M_{β } . Using an electron device sample, element distribution maps of Si, Ti, and W were obtained using a Si K_{α 1} X-ray energy resolution of 9.7 eV FWHM.

  4. Classification of Multiple Types of Organic Carbon Composition in Atmospheric Particles by Scanning Transmission X-Ray Microscopy Analysis

    Kilcoyne, Arthur L; Takahama, S.; Gilardoni, S.; Russell, L.M.; Kilcoyne, A.L.D.

    2007-05-16

    A scanning transmission X-ray microscope at the Lawrence Berkeley National Laboratory is used to measure organic functional group abundance and morphology of atmospheric aerosols. We present a summary of spectra, sizes, and shapes observed in 595 particles that were collected and analyzed between 2000 and 2006. These particles ranged between 0.1 and 12 mm and represent aerosols found in a large range of geographical areas, altitudes, and times. They include samples from seven different field campaigns: PELTI, ACE-ASIA, DYCOMS II, Princeton, MILAGRO (urban), MILAGRO (C-130), and INTEX-B. At least 14 different classes of organic particles show different types of spectroscopic signatures. Different particle types are found within the same region while the same particle types are also found in different geographical domains. Particles chemically resembling black carbon, humic-like aerosols, pine ultisol, and secondary or processed aerosol have been identified from functional group abundance and comparison of spectra with those published in the literature.

  5. Unraveling the redox behavior of a CoMoS hydrodesulfurization catalyst : A scanning transmission X-ray microscopy study in the tender X-ray range

    Al Samarai, Mustafa; Meirer, Florian; Karunakaran, Chithra; Wang, Jian; Vogt, Eelco T C; Zandbergen, Henny W.; Weber, Thomas; Weckhuysen, Bert M.; De Groot, Frank M F

    2015-01-01

    We visualize the elemental zoning in an alumina-supported cobalt molybdenum sulfide (CoMoS) catalyst with scanning transmission X-ray microscopy (STXM). We use the Canadian Light Source beamline 10-ID's (SM) unique combination of soft X-ray and tender X-ray STXM to determine the spatial variation of

  6. EVALUATION OF THE ULTRASTRUCTURE OF THE SMALL INTESTINE OF HIV INFECTED CHILDREN BY TRANSMISSION AND SCANNING ELECTRONIC MICROSCOPY

    Christiane Araujo Chaves LEITE

    2013-03-01

    Full Text Available Objectives To describe HIV children's small intestinal ultrastructural findings. Methods Descriptive, observational study of small intestine biopsies performed between August 1994 and May 1995 at São Paulo, SP, Brazil. This material pertained to 11 HIV infected children and was stored in a laboratory in paraffin blocks. Scanning and transmission electronic microscopy were used to view those intestine samples and ultrastructural findings were described by analyzing digitalized photos of this material. Ethical Committee approval was obtained. Results In most samples scanning microscopy showed various degrees of shortening and decreasing number of microvilli and also completes effacements in some areas. Derangement of the enterocytes was seen frequently and sometimes cells well defined borders limits seemed to be loosened. In some areas a mucous-fibrin like membrane with variable thickness and extension appeared to partially or totally coat the epithelial surface. Fat drops were present in the intestinal lumen in various samples and a bacterium morphologically resembling bacilli was seen in two occasions. Scanning microscopy confirmed transmission microscopy microvilli findings and also showed little “tufts” of those structures. In addition, it showed an increased number of vacuoles and multivesicular bodies inside various enterocytes, an increased presence of intraepithelial lymphocytes, mitochondrial vacuolization and basement membrane enlargement in the majority of samples analyzed. However, some samples exhibited normal aspect. Conclusions Our study showed the common occurrence of various important intestinal ultrastructural alterations with variable degrees among HIV infected children, some of them in our knowledge not described before. Objetivos Descrever achados ultra-estruturais do intestino delgado de crianças infectadas pelo HIV. Métodos Estudo descritivo, observacional de biopsias do intestino delgado, realizada entre agosto de

  7. Characterization and classification of psittacine atherosclerotic lesions by histopathology, digital image analysis, transmission and scanning electron microscopy.

    Beaufrère, Hugues; Nevarez, Javier G; Holder, Kali; Pariaut, Romain; Tully, Thomas N; Wakamatsu, Nobuko

    2011-10-01

    Atherosclerosis is a degenerative and inflammatory vascular disease characterized in mammals and birds by the accumulation of inflammatory cells, lipids, calcium, and formation of large fibrofatty lesions within the intima of arteries resulting in the disorganization of the arterial wall and stenosis of the lumen. Despite the high incidence of atherosclerosis in parrots and the high number of case reports, there are few pathologic investigations and the ultrastructural study of the lesions has not been documented. Sixty-three major arteries were collected from 24 psittacine birds of 11 species during routine post-mortem examinations. Samples from the major arteries were fixed in 2% paraformaldehyde and 1.25% glutaraldehyde, and processed for transmission electron microscopy (TEM) and scanning electron microscopy (SEM). Additional samples were fixed in 10% formalin and embedded in paraffin for histological examination. Additional histochemical stains for calcium, elastic fibres, and lipid were performed. Toluidine blue-stained 0.5 µm-thick resin sections were also obtained. Digital image analysis was performed to provide objective quantitative information on the different lesions. The histopathology and ultrastructure of psittacine atherosclerosis were found to be similar to other avian and mammalian species. Seven lesion types could be described, which were similar to the human classification system. Digital image analysis, TEM, and SEM helped to further describe the lesions and refine the classification system. TEM findings were similar to other avian and mammalian species with the notable presence of macrophage-derived and smooth muscle cell-derived foam cells and extracellular lipid. SEM revealed various stages of endothelial surface defects and, occasionally, adherent blood cells. PMID:21879992

  8. Development of a parallel detection and processing system using a multidetector array for wave field restoration in scanning transmission electron microscopy.

    Taya, Masaki; Matsutani, Takaomi; Ikuta, Takashi; Saito, Hidekazu; Ogai, Keiko; Harada, Yoshihito; Tanaka, Takeo; Takai, Yoshizo

    2007-08-01

    A parallel image detection and image processing system for scanning transmission electron microscopy was developed using a multidetector array consisting of a multianode photomultiplier tube arranged in an 8 x 8 square array. The system enables the taking of 64 images simultaneously from different scattered directions with a scanning time of 2.6 s. Using the 64 images, phase and amplitude contrast images of gold particles on an amorphous carbon thin film could be separately reconstructed by applying respective 8 shaped bandpass Fourier filters for each image and multiplying the phase and amplitude reconstructing factors. PMID:17764327

  9. Scanning electron microscopic, transmission electron microscopic, and confocal laser scanning microscopic observation of fibroblasts cultured on microgrooved surfaces of bulk titanium substrata

    Braber, den E.T.; Jansen, H.V.; Boer, de M.J.; Croes, H.J.E.; Elwenspoek, M.; Ginsel, L.A.; Jansen, J.A.

    1998-01-01

    During this study, microtechnology and plasma etching were used to produce gratings 1.0 (TiD01), 2.0 (TiD02), 5.0 (TiD05), and 10.0 µm wide (TiD10) into commercially pure titanium wafers. After incubation of rat dermal fibroblast (RDFs) on these surfaces for 3 days, the cells were observed with scan

  10. Composition analysis of a polymer electrolyte membrane fuel cell microporous layer using scanning transmission X-ray microscopy and near edge X-ray absorption fine structure analysis

    George, Michael G.; Wang, Jian; Banerjee, Rupak; Bazylak, Aimy

    2016-03-01

    The novel application of scanning transmission X-ray microscopy (STXM) to the microporous layer (MPL) of a polymer electrolyte membrane fuel cell is investigated. A spatially resolved chemical component distribution map is obtained for the MPL of a commercially available SGL 25 BC sample. This is achieved with near edge X-ray absorption fine structure spectroscopic analysis. Prior to analysis the sample is embedded in non-reactive epoxy and ultra-microtomed to a thickness of 100 nm. Polytetrafluoroethylene (PTFE), carbon particle agglomerates, and supporting epoxy resin distributions are identified and reconstructed for a scanning area of 6 μm × 6 μm. It is observed that the spatial distribution of PTFE is strongly correlated to the carbon particle agglomerations. Additionally, agglomerate structures of PTFE are identified, possibly indicating the presence of a unique mesostructure in the MPL. STXM analysis is presented as a useful technique for the investigation of chemical species distributions in the MPL.

  11. Correlative Fluorescence Microscopy and Scanning Transmission Electron Microscopy of Quantum Dot Labeled Proteins in Whole Cells in Liquid

    Dukes, Madeline J.; Peckys, Diana B.; de Jonge, Niels

    2010-01-01

    Correlative fluorescence microscopy and transmission electron microscopy (TEM) is a state-of-the-art microscopy methodology to study cellular function, combining the functionality of light microscopy with the high resolution of electron microscopy. However, this technique involves complex sample preparation procedures due to its need for either thin sections or frozen samples for TEM imaging. Here, we introduce a novel correlative approach capable of imaging whole eukaryotic cells in liquid w...

  12. Histological, Scanning And Transmission Electron Microscopic Studies On The Possible Protective Role Of Ginger Extract Against AcrylamideInduced Intestinal Damage In Mice

    Hala Galal El-Tantawi

    2007-12-01

    Full Text Available Objective: This study was carried out to evaluate the protective effect of ginger Zingeber officinale extract (ZOE against the acrylamide (AC which is an industrial chemical used in water treatment and it is synthesized during cooking of starch food at high temperature. Method: Thirty adult male albino mice, each weighs 20-25 g were divided into three groups (10 mice/group: (Icontrol group. (IIacrylamide treated group. (III acrylamide & ginger group. Acrylamide was given to experimental animals in the drinking water at a non-lethal dose of 200 p.p.m for 10 weeks (3 days/week. Ginger extract was orally administrated at 50 mg/L (~5 ml/day for 10 weeks (3 days/week. The ileum samples were collected for light microscope study and for scanning and transmission electron microscope examination. Results: This study revealed that acrylamide induces pathological changes of the ileum of the treated mice specially the absorptive epithelial cells. The scanning electron microscopic study revealed damage of the ileal villi, some red blood corpuscles appeared at the site of damage. The transmission electron microscopic examination clearly demonstrated degeneration of most cell organelles as mitochondria, deterioration and degranulation of the rough endoplasmic reticulum, dilatation of Golgi apparatus. Conclusion: The administration of ginger extract decreased the histological alterations and ensuring the anti-inflammatory, and antitoxic effects of ZOE at its chosen dosage level

  13. Submicron mass spectrometry imaging of single cells by combined use of mega electron volt time-of-flight secondary ion mass spectrometry and scanning transmission ion microscopy

    In order to better understand biochemical processes inside an individual cell, it is important to measure the molecular composition at the submicron level. One of the promising mass spectrometry imaging techniques that may be used to accomplish this is Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), using MeV energy heavy ions for excitation. MeV ions have the ability to desorb large intact molecules with a yield that is several orders of magnitude higher than conventional SIMS using keV ions. In order to increase the spatial resolution of the MeV TOF-SIMS system, we propose an independent TOF trigger using a STIM (scanning transmission ion microscopy) detector that is placed just behind the thin transmission target. This arrangement is suitable for biological samples in which the STIM detector simultaneously measures the mass distribution in scanned samples. The capability of the MeV TOF-SIMS setup was demonstrated by imaging the chemical composition of CaCo-2 cells

  14. Submicron mass spectrometry imaging of single cells by combined use of mega electron volt time-of-flight secondary ion mass spectrometry and scanning transmission ion microscopy

    Siketić, Zdravko; Bogdanović Radović, Ivančica; Jakšić, Milko; Popović Hadžija, Marijana; Hadžija, Mirko [Ruđer Bošković Institute, Bijenička cesta 54, 10000 Zagreb (Croatia)

    2015-08-31

    In order to better understand biochemical processes inside an individual cell, it is important to measure the molecular composition at the submicron level. One of the promising mass spectrometry imaging techniques that may be used to accomplish this is Time-of-Flight Secondary Ion Mass Spectrometry (TOF-SIMS), using MeV energy heavy ions for excitation. MeV ions have the ability to desorb large intact molecules with a yield that is several orders of magnitude higher than conventional SIMS using keV ions. In order to increase the spatial resolution of the MeV TOF-SIMS system, we propose an independent TOF trigger using a STIM (scanning transmission ion microscopy) detector that is placed just behind the thin transmission target. This arrangement is suitable for biological samples in which the STIM detector simultaneously measures the mass distribution in scanned samples. The capability of the MeV TOF-SIMS setup was demonstrated by imaging the chemical composition of CaCo-2 cells.

  15. Scanning and transmission electron microscopy of a craniopharyngioma: x-ray microanalytical study of the intratumoral mineralized deposits

    Vilches, J.; Lopez, A.; Martinez, M.C.; Gomez, J.; Barbera, J.

    This paper discusses the value of scanning electron microscopy (SEM) and x-ray microanalysis in the classification of craniopharyngiomas. This neoplasm shows epithelial nest, cords of cuboid cells, foci of squamous metaplasia, and microcystic degeneration. SEM reveals that the epithelial cysts are lined with elongated cells that possess numerous microvilli and blebs and that some cysts are lined with polyhedral cells. The microvilli are interpreted as characteristic of the fast growing craniopharyngiomas. A microanalytical study of the calcified areas reveals the presence of magnesium, phosphorus, and calcium.

  16. A clinical evaluation of the quantitative accuracy of simultaneous emission/transmission scanning in whole-body positron emission tomography

    We present a clinical evaluation of the quantitative bias which is introduced during simultaneous emission/transmission (SET) acquisition for the application of whole-body positron emission tomography (PET) with fluorine-18 2-fluoro-2-deoxy-d-glucose. The quantitative accuracy of the SET technique was assessed by means of a clinical study involving 28 patients and a realistic phantom experiment. In the clinical study, SET overestimated the activity concentration in the tumours by a factor of approximately 1.10, but in the phantom study, where the tumours were smaller, the bias was found to increase to a value of 1.39. The bias in the soft tissue regions of the patient studies varied between 1.03 and 1.36, and close agreement was observed with the corresponding phantom results. The extent of the bias increased as the local activity concentration decreased and we attribute the effect to scattered photons from the transmission source which are detected in the emission window during SET. (orig.)

  17. Hubble Space Telescope hot Jupiter Transmission Spectral Survey: detection of water in HAT-P-1b from Wide Field Camera 3 near-infrared spatial scan observations

    Wakeford, H R; Deming, D; Gibson, N P; Fortney, J J; Burrows, A S; Ballester, G; Nikolov, N; Aigrain, S; Henry, G; Knutson, H; Etangs, A Lecavelier des; Pont, F; Showman, A P; Vidal-Madjar, A; Zahnle, K

    2013-01-01

    We present Hubble Space Telescope near-infrared transmission spectroscopy of the transiting hot-Jupiter HAT-P-1b. We observed one transit with Wide Field Camera 3 using the G141 low-resolution grism to cover the wavelength range 1.087- 1.678 {\\mu}m. These time series observations were taken with the newly available spatial scan mode that increases the duty cycle by nearly a factor of two, thus improving the resulting photometric precision of the data. We measure a planet-to-star radius ratio of Rp/R*=0.11709+/-0.00038 in the white light curve with the centre of transit occurring at 2456114.345+/-0.000133 (JD). We achieve S/N levels per exposure of 1840 (0.061%) at a resolution of {\\Delta\\lambda}=19.2nm (R~70) in the 1.1173 - 1.6549{\\mu}m spectral region, providing the precision necessary to probe the transmission spectrum of the planet at close to the resolution limit of the instrument. We compute the transmission spectrum using both single target and differential photometry with similar results. The resultan...

  18. Microstructural study on degradation mechanism of layered LiNi0.6Co0.2Mn0.2O2 cathode materials by analytical transmission electron microscopy

    Kim, Na Yeon; Yim, Taeeun; Song, Jun Ho; Yu, Ji-Sang; Lee, Zonghoon

    2016-03-01

    Electrochemical performance of lithium ion batteries is associated with structural and chemical stability of electrode materials. In the case of nickel-rich layered cathode materials LiNi0.6Co0.2Mn0.2O2, cation mixing, which results from the migration of transition metal ions into vacant lithium sites, is accelerated owing to similar ionic radii between nickel and lithium. However, the inevitable lattice distortions and chemical evolution have not been investigated intensely. In this paper, we report the structural evolution localized at surface regions through electron diffraction and high resolution imaging analyses with aberration-corrected transmission electron microscopy and scanning transmission electron microscopy. Repetition of volumetric change generates cracks and voids associated with deterioration of electrochemical performance. Structural change is related with (003) intensity in electron diffraction and it can be presented by dark field transmission electron microscopy imaging at a glance. Drastic structural degradation during early cycling shows relation with rapid capacity and voltage fade. Electron energy loss spectroscopy elucidates that the structural evolution caused by the migration of Ni ions accompanies chemical modification of Mn ions and creation of hole states at the O2p level. This study provides an insight into correlating structural and chemical evolution with degradation mechanism on battery performances of LiNi0.6Co0.2Mn0.2O2 cathode materials.

  19. Minimizing artifacts resulting from respiratory and cardiac motion by optimization of the transmission scan in cardiac PET/CT

    The introduction of positron emission/computed tomography (PET/CT) systems coupled with multidetector CT arrays has greatly increased the amount of clinical information in myocardial perfusion studies. The CT acquisition serves the dual role of providing high spatial anatomical detail and attenuation correction for PET. However, the differences between the interaction of respiratory and cardiac cycles in the CT and PET acquisitions presents a challenge when using the CT to determine PET attenuation correction. Three CT attenuation correction protocols were tested for their ability to produce accurate emission images: gated, a step mode acquisition covering the diastolic heart phase; normal, a high-pitch helical CT; and slow, a low-pitch, low-temporal-resolution helical CT. The amount of cardiac tissue in the emission image that overlaid lung tissue in the transmission image was used as the measure of mismatch between acquisitions. Phantom studies simulating misalignment of the heart between the transmission and emission sequences were used to correlate the amount of mismatch with the artificial defect changes in the emission image. Consecutive patients were studied prospectively with either paired gated (diastolic phase, 120 kVp, 280 mA, 2.6 s) and slow CT (0.562:1 pitch, 120 kVp, Auto-mA, 16 s) or paired normal (0.938:1 pitch, 120 kVp, Auto-mA, 4.8 s) and slow CT protocols, prior to a Rb-82 perfusion study. To determine the amount of mismatch, the transmission and emission images were converted to binary representations of attenuating tissue and cardiac tissue and overlaid using their native registration. The number of cardiac tissue pixels from the emission image present in the CT lung field yielded the magnitude of misalignment represented in terms of volume, of where a small volume indicates better registration. Acquiring a slow CT improved registration between the transmission and emission acquisitions compared to the gated and normal CT protocols. The volume

  20. Fine structures and ion images on fresh frozen dried ultrathin sections by transmission electron and scanning ion microscopy

    Takaya, K.; Okabe, M.; Sawataishi, M.; Takashima, H.; Yoshida, T

    2003-01-15

    Ion microscopy (IM) of air-dried or freeze-dried cryostat and semi-thin cryosections has provided ion images of elements and organic substances in wide areas of the tissue. For reproducible ion images by a shorter time of exposure to the primary ion beam, fresh frozen dried ultrathin sections were prepared by freezing the tissue in propane chilled with liquid nitrogen, cryocut at 60 nm, mounted on grids and silicon wafer pieces, and freeze-dried. Rat Cowper gland and sciatic nerve, bone marrow of the rat administered of lithium carbonate, tree frog and African toad spleen and buffy coat of atopic dermatitis patients were examined. Fine structures and ion images of the corresponding areas in the same or neighboring sections were observed by transmission electron microscopy (TEM) followed by sector type and time-of-flight type IM. Cells in the buffy coat contained larger amounts of potassium and magnesium while plasma had larger amounts of sodium and calcium. However, in the tissues, lithium, sodium, magnesium, calcium and potassium were distributed in the cell and calcium showed a granular appearance. A granular cell of the tree frog spleen contained sodium and potassium over the cell and magnesium and calcium were confined to granules.

  1. Scanning and transmission electron microscopy of the tegument of Paranaella luquei Kohn, Baptista-Farias & Cohen, 2000 (Microcotylidae, Monogenea, parasite of a Brazilian catfish, Hypostomus regani

    SC Cohen

    2001-05-01

    Full Text Available The surface topography and ultrastructure of the tegument of Paranaella luquei Kohn, Baptista-Farias & Cohen, 2000, a microcotylid monogenean parasite from the gills of Hypostomus regani (Ihering, 1905 (Loricariidae was studied by scanning (SEM and transmission electron microscopy (TEM. By SEM, it was observed that the tegument presents transversal ridges, forming folds in the ventral and dorsal surfaces and microvillous-like tegumental projections in the anterior and median regions of body. These projections were also observed by TEM. The tegument is made up of a syncytium delimited by apical and basal plasma membranes, containing inclusion bodies and mitochondria, connected to the nucleated region by means of cytoplasmatic processes. The tegumental cells present a well developed nucleus and cytoplasm containing inclusion bodies, similar to those found on the external layer, mitochondria, rough endoplasmatic reticulum and free ribossomes.

  2. Preparation and Loading Process of Single Crystalline Samples into a Gas Environmental Cell Holder for In Situ Atomic Resolution Scanning Transmission Electron Microscopic Observation.

    Straubinger, Rainer; Beyer, Andreas; Volz, Kerstin

    2016-06-01

    A reproducible way to transfer a single crystalline sample into a gas environmental cell holder for in situ transmission electron microscopic (TEM) analysis is shown in this study. As in situ holders have only single-tilt capability, it is necessary to prepare the sample precisely along a specific zone axis. This can be achieved by a very accurate focused ion beam lift-out preparation. We show a step-by-step procedure to prepare the sample and transfer it into the gas environmental cell. The sample material is a GaP/Ga(NAsP)/GaP multi-quantum well structure on Si. Scanning TEM observations prove that it is possible to achieve atomic resolution at very high temperatures in a nitrogen environment of 100,000 Pa. PMID:27026281

  3. Evaluation of Al3Mg2 precipitates and Mn-rich phase in aluminum-magnesium alloy based on scanning transmission electron microscopy imaging

    Zhu, Yakun [ORNL; Cullen, David A [ORNL; Kar, Soumya [ORNL; Free, Michael P [ORNL; Allard Jr, Lawrence Frederick [ORNL

    2012-01-01

    Scanning transmission electron microscopy (STEM) and energy dispersive X-ray spectroscopy (EDS) were used to observe intergranular and intragranular -phase (Al3Mg2) formation and growth in as-received sample and long-term (~ 1 year) thermally treated samples of 5083-H131 alloy. Rod-shaped and equiaxed particles rich in Mn, Fe, and Cr were present in the as-received and heat treated samples. The -phase precipitated along grain boundaries as well as around and between preexisting Mn-Fe-Cr rich particles. The measured thickness of -phase along grain boundaries was lower than Zener Hillert diffusion model predicted value and the potential reasons were theoretically analyzed. Dislocation networks, grain boundaries, and different preexisting particles were observed to contribute to Mg diffusion and -phase precipitation.

  4. Defect detection and size estimation in billet from profile of time-of-flight using ultrasonic transmission method with linear scanning

    Miyamoto, Ryusuke; Mizutani, Koichi; Ebihara, Tadashi; Wakatsuki, Naoto

    2015-07-01

    In this study, defect detection and size estimation in billet by transmission method with linear scanning were carried out and the validity of the method was evaluated by numerical simulation. In addition, the suitable signal frequency and aperture of transducers were clarified. As a result, the following were found: a defect can be detected, signals with frequencies lower than those generally used in conventional ultrasonic testing (i.e., 0.5-1.5 MHz) are desirable, and the time-of-flight (TOF) deviation Δτ becomes largest when the wavelength at center frequency and the aperture of transducers are comparable. Defect size can be estimated when a single defect exists alone and the defect is not near the surface of a billet. Although defect size estimation becomes difficult when the defect is near the surface of a billet, the defect can be detected by our proposed method.

  5. Analytical Scanning and Transmission Electron Microscopy of Laboratory Impacts on Stardust Aluminium Foils: Interpreting Impact Crater Morphology and the Composition of Impact Residues.

    Kearsley, A T; Graham, G A; Burchell, M J; Cole, M J; Dai, Z R; Teslich, N; Chater, R; Wozniakiewicz, P A; Spratt, J; Jones, G

    2006-10-19

    The known encounter velocity (6.1kms{sup -1}) between the Stardust spacecraft and the dust emanating from the nucleus of comet Wild 2 has allowed realistic simulation of dust collection in laboratory experiments designed to validate analytical methods for the interpretation of dust impacts on the aluminium foil components of the Stardust collector. In this report we present information on crater gross morphology, the pre-existing major and trace element composition of the foil, geometrical issues for energy dispersive X-ray analysis of the impact residues in scanning electron microscopes, and the modification of dust chemical composition during creation of impact craters as revealed by analytical transmission electron microscopy. Together, these observations help to underpin the interpretation of size, density and composition for particles impacted upon the Stardust aluminium foils.

  6. Varied-space grazing incidence gratings in high resolution scanning spectrometers

    We discuss the dominant geometrical aberrations of a grazing incidence reflection grating and new techniques which can be used to reduce or eliminate them. Convergent beam geometries and the aberration correction possible with varied groove spacings are each found to improve the spectral resolution and speed of grazing incidence gratings. In combination, these two techniques can result in a high resolution (λ/Δλ > 104) monochromator or scanning spectrometer with a simple rotational motion for scanning wavelength or selecting the spectral band. 21 refs., 4 figs

  7. Deciphering the physics and chemistry of perovskites with transmission electron microscopy.

    Polking, Mark J

    2016-03-17

    Perovskite oxides exhibit rich structural complexity and a broad range of functional properties, including ferroelectricity, ferromagnetism, and superconductivity. The development of aberration correction for the transmission electron microscope and concurrent progress in electron spectroscopy, electron holography, and other techniques has fueled rapid progress in the understanding of the physics and chemistry of these materials. New techniques based on the transmission electron microscope are first surveyed, and the applications of these techniques for the study of the structure, chemistry, electrostatics, and dynamics of perovskite oxides are then explored in detail, with a particular focus on ferroelectric materials. PMID:26762871

  8. Scanning system

    An improved transversally cutting radionuclide scanning system is described which can be used for medical diagnosis and medical treatment of men, particularly, for brain investingations. 99mTc43 is named as a radionuclide. The device described is more sensitive, and displays results in a shorter period of time than devices known until now. By means of laser emitting diodes a continuous transmission and collection of signals is obtained, due to a rotating picture framework of offset and meshing detectors surrounding completely the scanning field around a single rotation axis - coaxialy with the axis of the head. Signals are processed and displayed by a connected computer. Description in detail, 7 figures. (UWI)

  9. Nanometer scale correlation of optical and structural properties of individual InGaN/GaN nanorods by scanning transmission electron microscope cathodoluminescence

    A potential benefit of nanorods as light emitters, aside from their very high crystal quality, relies on better light extraction efficiency as compared to thin films, because of the high surface to volume ratio. In this study we present a direct nano-scale correlation of the optical properties with the actual crystalline structure of ordered InGaN/GaN nanorods using low temperature cathodoluminescence spectroscopy in a scanning transmission electron microscope (STEM-CL). Direct comparison of the high-angle annular dark field image with the simultaneously recorded panchromatic CL mapping at 15 K reveals a weak luminescence from the bottom GaN layer. We observe the highest CL intensity in the middle of the InGaN region. The spectral position of the InGaN emission shifts continuously red from the GaN/InGaN interface (λ=409 nm) to the NR top (λ=446 nm) due to lattice pulling effects and InGaN partial decomposition. Additionally, optical active basal stacking faults in the GaN layer emitting at 366 nm can be found.

  10. Scanning and transmission electron microscopy of the histopathological impact of Macrogyrodactylus clarii (Monogenea: Gyrodactylidae) on the gills of catfish, Clarias gariepinus.

    El-Naggar, Mohammed Mohammed; Cable, Joanne; Zaky Arafa, Safaa; El-Abbassy, Samir Ahmed; Kearn, Graham C

    2016-01-01

    Scanning and transmission electron microscopy (TEM) were used to study the histopathological effects of the monogenean Macrogyrodactylus clarii Gussev, 1961 on the gills of the catfish Clarias gariepinus (Burchell). Suction generated during attachment created 'footprints' on host surfaces in which the host tissues were elevated above the general gill surface. 'Footprints' were bordered by four clefts caused by the muscular flaps on the anterior, lateral and posterior margins of the haptor. The hamuli points penetrate the gill tissue but no evidence was found for the insertion of the marginal hooklets. At the site of attachment, host cells adjacent to the lateral flaps often appeared compressed and widely spaced with large intercellular spaces. Desquamation of these surface epithelia was also apparent and some of the widely spaced epithelial cells had pseudopodium-like processes. Cells within the upper surface epithelial layer of the host were vacuolated and necrotic. Ruptured blood capillaries (blood spaces) in the secondary gill lamellae contained atypical compressed erythrocytes, agranular and granular leucocytes and evidence of haemorrhaging. Cells with fibrotic cytoplasm, putative phagocytes and host mucous cells were evidence of a host response at the site of parasite attachment. The possible role of these cells is discussed in relation to host resistance against infection. PMID:27311695

  11. Interplay of strain and indium incorporation in InGaN/GaN dot-in-a-wire nanostructures by scanning transmission electron microscopy.

    Woo, Steffi Y; Gauquelin, Nicolas; Nguyen, Hieu P T; Mi, Zetian; Botton, Gianluigi A

    2015-08-28

    The interplay between strain and composition is at the basis of heterostructure design to engineer new properties. The influence of the strain distribution on the incorporation of indium during the formation of multiple InGaN/GaN quantum dots (QDs) in nanowire (NW) heterostructures has been investigated, using the combined techniques of geometric phase analysis of atomic-resolution images and quantitative elemental mapping from core-loss electron energy-loss spectroscopy within scanning transmission electron microscopy. The variation in In-content between successive QDs within individual NWs shows a dependence on the magnitude of compressive strain along the growth direction within the underlying GaN barrier layer, which affects the incorporation of In-atoms to minimize the local effective strain energy. Observations suggest that the interfacial misfit between InGaN/GaN within the embedded QDs is mitigated by strain partitioning into both materials, and results in normal stresses inflicted by the presence of the surrounding GaN shell. These experimental measurements are linked to the local piezoelectric polarization fields for individual QDs, and are discussed in terms of the photoluminescence from an ensemble of NWs. PMID:26234582

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

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

    2013-11-01

    High angle annular dark field (HAADF)-scanning transmission electron microscope (STEM) data is increasingly being used in the physical sciences to research materials in 3D because it reduces the effects of Bragg diffraction seen in bright field TEM data. Typically, tomographic reconstructions are performed by directly applying either filtered back projection (FBP) or the simultaneous iterative reconstruction technique (SIRT) to the data. Since HAADF-STEM tomography is a limited angle tomography modality with low signal to noise ratio, these methods can result in significant artifacts in the reconstructed volume. In this paper, we develop a model based iterative reconstruction algorithm for HAADF-STEM tomography. We combine a model for image formation in HAADF-STEM tomography along with a prior model to formulate the tomographic reconstruction as a maximum a posteriori probability (MAP) estimation problem. Our formulation also accounts for certain missing measurements by treating them as nuisance parameters in the MAP estimation framework. We adapt the iterative coordinate descent algorithm to develop an efficient method to minimize the corresponding MAP cost function. Reconstructions of simulated as well as experimental data sets show results that are superior to FBP and SIRT reconstructions, significantly suppressing artifacts and enhancing contrast. PMID:23955748

  13. Initiation and recovery processes of endotoxin induced disseminated intravascular coagulation (DIC: scanning and transmission electron microscopic observations of rat renal tissues.

    Miyashima,Takanao

    1989-04-01

    Full Text Available To clarify the initiation, development and recovery processes of disseminated intravascular coagulation (DIC, rat glomerular capillaries and fibrin thrombi were examined under transmission and scanning electron microscopes. DIC was induced in rats by a single intraperitoneal injection of endotoxin (Et., 7.5 mg/kg lipopolysaccharide:B, E. coli 026:B6. At 2 h after Et. injection, the endothelial surface of the glomerular capillary became irregular with projections like a sea anemone. At 4 h after Et. injection, agglomerated fibrin thrombi composed of fibrin fiber bundles with fine cross-striated fibriform structures were observed in the capillary lumen. The fibrin thrombi gradually changed into fine reticular systems suggesting a degradation process by 6 h after Et. injection, and formed a coarse granular agglomerate by 8 h after Et. injection. These fibrin thrombi disappeared within 12 h of Et. injection, but the endothelial surface remained edematous. At 24 h after Et. injection, the microstructure of the glomerular capillaries returned normal. Based on these observations, we concluded that DIC was primarily initiated by injury to the capillary endothelium, and that changes on the endothelial surface contributed to the development of DIC.

  14. A Scanning Transmission X-ray Microscopy Study of Cubic and Orthorhombic C3A and Their Hydration Products in the Presence of Gypsum

    Vanessa Rheinheimer

    2016-08-01

    Full Text Available This paper shows the microstructural differences and phase characterization of pure phases and hydrated products of the cubic and orthorhombic (Na-doped polymorphs of tricalcium aluminate (C3A, which are commonly found in traditional Portland cements. Pure, anhydrous samples were characterized using scanning transmission X-ray microscopy (STXM, X-ray photoelectron spectroscopy (XPS and X-ray diffraction (XRD and demonstrated differences in the chemical and mineralogical composition as well as the morphology on a micro/nano-scale. C3A/gypsum blends with mass ratios of 0.2 and 1.9 were hydrated using a water/C3A ratio of 1.2, and the products obtained after three days were assessed using STXM. The hydration process and subsequent formation of calcium sulfate in the C3A/gypsum systems were identified through the changes in the LIII edge fine structure for Calcium. The results also show greater Ca LII binding energies between hydrated samples with different gypsum contents. Conversely, the hydrated samples from the cubic and orthorhombic C3A at the same amount of gypsum exhibited strong morphological differences but similar chemical environments.

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

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

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

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

    2010-01-01

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

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

    Bennemann, R; Pietzsch-Rohrschneider, I

    1978-10-30

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

  18. A MEMS-based heating holder for the direct imaging of simultaneous in-situ heating and biasing experiments in scanning/transmission electron microscopes.

    Mele, Luigi; Konings, Stan; Dona, Pleun; Evertz, Francis; Mitterbauer, Christoph; Faber, Pybe; Schampers, Ruud; Jinschek, Joerg R

    2016-04-01

    The introduction of scanning/transmission electron microscopes (S/TEM) with sub-Angstrom resolution as well as fast and sensitive detection solutions support direct observation of dynamic phenomena in-situ at the atomic scale. Thereby, in-situ specimen holders play a crucial role: accurate control of the applied in-situ stimulus on the nanostructure combined with the overall system stability to assure atomic resolution are paramount for a successful in-situ S/TEM experiment. For those reasons, MEMS-based TEM sample holders are becoming one of the preferred choices, also enabling a high precision in measurements of the in-situ parameter for more reproducible data. A newly developed MEMS-based microheater is presented in combination with the new NanoEx™-i/v TEM sample holder. The concept is built on a four-point probe temperature measurement approach allowing active, accurate local temperature control as well as calorimetry. In this paper, it is shown that it provides high temperature stability up to 1,300°C with a peak temperature of 1,500°C (also working accurately in gaseous environments), high temperature measurement accuracy (<4%) and uniform temperature distribution over the heated specimen area (<1%), enabling not only in-situ S/TEM imaging experiments, but also elemental mapping at elevated temperatures using energy-dispersive X-ray spectroscopy (EDS). Moreover, it has the unique capability to enable simultaneous heating and biasing experiments. PMID:26818213

  19. Cardiac Myocyte Diversity and a Fibroblast Network in the Junctional Region of the Zebrafish Heart Revealed by Transmission and Serial Block-Face Scanning Electron Microscopy

    Lafontant, Pascal J.

    2013-08-23

    The zebrafish has emerged as an important model of heart development and regeneration. While the structural characteristics of the developing and adult zebrafish ventricle have been previously studied, little attention has been paid to the nature of the interface between the compact and spongy myocardium. Here we describe how these two distinct layers are structurally and functionally integrated. We demonstrate by transmission electron microscopy that this interface is complex and composed primarily of a junctional region occupied by collagen, as well as a population of fibroblasts that form a highly complex network. We also describe a continuum of uniquely flattened transitional cardiac myocytes that form a circumferential plate upon which the radially-oriented luminal trabeculae are anchored. In addition, we have uncovered within the transitional ring a subpopulation of markedly electron dense cardiac myocytes. At discrete intervals the transitional cardiac myocytes form contact bridges across the junctional space that are stabilized through localized desmosomes and fascia adherentes junctions with adjacent compact cardiac myocytes. Finally using serial block-face scanning electron microscopy, segmentation and volume reconstruction, we confirm the three-dimensional nature of the junctional region as well as the presence of the sheet-like fibroblast network. These ultrastructural studies demonstrate the previously unrecognized complexity with which the compact and spongy layers are structurally integrated, and provide a new basis for understanding development and regeneration in the zebrafish heart. © 2013 Lafontant et al.

  20. Nanometer scale correlation of optical and structural properties of individual InGaN/GaN nanorods by scanning transmission electron microscope cathodoluminescence

    Mueller, Marcus; Schmidt, Gordon; Veit, Peter; Petzold, Silke; Bertram, Frank; Christen, Juergen [Institute of Experimental Physics, Otto-von-Guericke-University Magdeburg (Germany); Albert, Steven; Bengoechea-Encabo, Ana Maria; Sanchez-Garcia, Miguel Angel; Calleja, Enrique [ISOM e Departamento de Ingenieria Electronica, Universidad Politecnica de Madrid (Spain)

    2013-07-01

    A potential benefit of nanorods as light emitters, aside from their very high crystal quality, relies on better light extraction efficiency as compared to thin films, because of the high surface to volume ratio. In this study we present a direct nano-scale correlation of the optical properties with the actual crystalline structure of ordered InGaN/GaN nanorods using low temperature cathodoluminescence spectroscopy in a scanning transmission electron microscope (STEM-CL). Direct comparison of the high-angle annular dark field image with the simultaneously recorded panchromatic CL mapping at 15 K reveals a weak luminescence from the bottom GaN layer. We observe the highest CL intensity in the middle of the InGaN region. The spectral position of the InGaN emission shifts continuously red from the GaN/InGaN interface (λ=409 nm) to the NR top (λ=446 nm) due to lattice pulling effects and InGaN partial decomposition. Additionally, optical active basal stacking faults in the GaN layer emitting at 366 nm can be found.

  1. Scanning and transmission electron microscopy and X-ray analysisof leaf salt glands of Limoniastrum guyonianum Boiss. under NaCl salinity.

    Zouhaier, Barhoumi; Abdallah, Atia; Najla, Trabelsi; Wahbi, Djebali; Wided, Chaïbi; Aouatef, Ben Ammar; Chedly, Abdelly; Abderazzak, Smaoui

    2015-11-01

    Leaf salt glands of Limoniastrum guyonianum were examined by scanning and transmission electron microscopes and energy dispersive X-ray analysis (EDAX) system, after growing for three months on sandy soil with or without 300 mM NaCl. Results showed that salt glands were irregularly scattered on both leaf sides and sunk under the epidermal level. Salt excretion occurred in both conditions and is mainly composed of calcium and magnesium in control plants, and essentially sodium and chloride in plants subjected to salt treatment. A salt gland is comprised of collecting, accumulating, and central compartments, and is made up of total thirty-two cells. The collecting cells were characterized by large central vacuoles. Accumulating cells contain numerous, large, and unshaped vacuoles and rudimentary chloroplasts. The central compartment was comprised of four basal cells and each one is surmounted by an apical cell. The basal cells are granulated, containing large nucleus, numerous mitochondria, endoplasmic reticulum, ribosomes, polyribosomes, and small vacuoles or vesicles. Equally, the apical cells are rich in organelles. Application of 300 mM NaCl to the culture medium increased vacuoles number and size, and organelles density especially the mitochondria which suggests energy requirement for ions transport. The reduction in size and number of vacuoles toward the interior of salt glands of treated plants and the fusion of the smallest ones with the plasma membrane substantiate the implication of such vacuoles in salt excretion process. The current study which is the first report on L. guyonianum salt gland has provided an in-depth understanding on structure-function relationship in the multicellular salt glands. PMID:26102605

  2. Effect of polymers on the nanostructure and on the carbonation of calcium silicate hydrates: a scanning transmission X-ray microscopy study

    Ha, J.

    2011-09-07

    This study investigated the effects of organic polymers (polyethylene glycol and hexadecyltrimethylammonium) on structures of calcium silicate hydrates (C-S-H) which is the major product of Portland cement hydration. Increased surface areas and expansion of layers were observed for all organic polymer modified C-S-H. The results from attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopic measurements also suggest lowered water contents in the layered structures for the C-S-H samples that are modified by organic polymers. Scanning transmission X-ray microscopy (STXM) results further supports this observation. We also observed difference in the extent of C-S-H carbonation due to the presence of organic polymers. No calcite formed in the presence of HDTMA whereas formation of calcite was observed with C-S-H sample modified with PEG. We suggest that the difference in the carbonation reaction is possibly due to the ease of penetration and diffusion of the CO 2. This observation suggests that CO 2 reaction strongly depends on the presence of organic polymers and the types of organic polymers incorporated within the C-S-H structure. This is the first comprehensive study using STXM to quantitatively characterize the level of heterogeneity in cementitious materials at high spatial and spectral resolutions. The results from BET, XRD, ATR-FTIR, and STXM measurements are consistent and suggest that C-S-H layer structures are significantly modified due to the presence of organic polymers, and that the chemical composition and structural differences among the organic polymers determine the extent of the changes in the C-S-H nanostructures as well as the extent of carbonation reaction. © 2011 Springer Science+Business Media, LLC.

  3. Atomic Resolution Transmission Electron Microscopy of Defects in Hexagonal Boron Nitride and Graphene

    Gibb, Ashley; Alem, Nasim; Song, Chengyu; Ciston, Jim; Zettl, Alex

    2014-03-01

    Monolayer sheets of sp2-bonded materials such as graphene and hexagonal boron nitride (h-BN) have been studied extensively due to their properties including high mechanical strength, thermal conductivity, stability, interesting electronic properties, and potential for integration into novel devices. Understanding the atomic scale structure of defects in these materials is important because defects can significantly affect the physical properties in these materials. In particular, understanding the dynamics of these defects explains much about the material's stability. We have synthesized h-BN and graphene using low pressure chemical vapor deposition and imaged defects using atomic resolution aberration corrected transmission electron microscopy.

  4. Frequency scanning microstrip antennas

    Danielsen, Magnus; Jørgensen, Rolf

    1979-01-01

    The principles of using radiating microstrip resonators as elements in a frequency scanning antenna array are described. The resonators are cascade-coupled. This gives a scan of the main lobe due to the phase-shift in the resonator in addition to that created by the transmission line phase...

  5. Application of transmission scan-based attenuation compensation to scatter-corrected thallium-201 myocardial single-photon emission tomographic images

    A practical method for scatter and attenuation compensation was employed in thallium-201 myocardial single-photon emission tomography (SPET or ECT) with the triple-energy-window (TEW) technique and an iterative attenuation correction method by using a measured attenuation map. The map was reconstructed from technetium-99m transmission CT (TCT) data. A dual-headed SPET gamma camera system equipped with parallel-hole collimators was used for ECT/TCT data acquisition and a new type of external source named ''sheet line source'' was designed for TCT data acquisition. This sheet line source was composed of a narrow long fluoroplastic tube embedded in a rectangular acrylic board. After injection of 99mTc solution into the tube by an automatic injector, the board was attached in front of the collimator surface of one of the two detectors. After acquiring emission and transmission data separately or simultaneously, we eliminated scattered photons in the transmission and emission data with the TEW method, and reconstructed both images. Then, the effect of attenuation in the scatter-corrected ECT images was compensated with Chang's iterative method by using measured attenuation maps. Our method was validated by several phantom studies and clinical cardiac studies. The method offered improved homogeneity in distribution of myocardial activity and accurate measurements of myocardial tracer uptake. We conclude that the above correction method is feasible because a new type of 99mTc external source may not produce truncation in TCT images and is cost-effective and easy to prepare in clinical situations. (orig.)

  6. Increase of brightness and transmission efficiency in flat panel display through serial synchronous scanning mode with double buffers%串行同步双缓冲扫描提高平板显示器的显示亮度和传送利用率

    陈章进; 陈峰; 冉峰; 徐美华; 郑方

    2007-01-01

    This paper presents a serial synchronous scanning mode in flat panel display(FPD)by adding a latch buffer between the seriaiizer and the driving buffer.Comparing with conventional techniques,the proposed structure can efficiently reduce the brightness loss and improve the transmission performance.Theoretical analysis and experimental results show that the ratio between the lightest weight display time and the relative transmission time is a tradeoff between brightness loss and transmission efficiency.

  7. Aberration Corrected Photoemission Electron Microscopy with Photonics Applications

    Fitzgerald, Joseph P. S.

    Photoemission electron microscopy (PEEM) uses photoelectrons excited from material surfaces by incident photons to probe the interaction of light with surfaces with nanometer-scale resolution. The point resolution of PEEM images is strongly limited by spherical and chromatic aberration. Image aberrations primarily originate from the acceleration of photoelectrons and imaging with the objective lens and vary strongly in magnitude with specimen emission characteristics. Spherical and chromatic aberration can be corrected with an electrostatic mirror, and here I develop a triode mirror with hyperbolic geometry that has two adjacent, field-adjustable regions. I present analytic and numerical models of the mirror and show that the optical properties agree to within a few percent. When this mirror is coupled with an electron lens, it can provide a large dynamic range of correction and the coefficients of spherical and chromatic aberration can be varied independently. I report on efforts to realize a triode mirror corrector, including design, characterization, and alignment in our microscope at Portland State University (PSU). PEEM may be used to investigate optically active nanostructures, and we show that photoelectron emission yields can be identified with diffraction, surface plasmons, and dielectric waveguiding. Furthermore, we find that photoelectron micrographs of nanostructured metal and dielectric structures correlate with electromagnetic field calculations. We conclude that photoemission is highly spatially sensitive to the electromagnetic field intensity, allowing the direct visualization of the interaction of light with material surfaces at nanometer scales and over a wide range of incident light frequencies.

  8. Aberration corrected STEM to study an ancient hair dyeing formula

    Patriarche, G.; Van Elslande, E.; Castaing, J.; Walter, P.

    2014-05-01

    Lead-based chemistry was initiated in ancient Egypt for cosmetic preparation more than 4000 years ago. Here, we study a hair-dyeing recipe using lead salts described in text since Greco-Roman times. We report direct evidence about the shape and distribution of PbS nanocrystals that form within the hair during blackening.

  9. Holographic Adaptive Laser Optics System (HALOS): Fast, Autonomous Aberration Correction

    Andersen, G.; MacDonald, K.; Gelsinger-Austin, P.

    2013-09-01

    We present an adaptive optics system which uses a multiplexed hologram to deconvolve the phase aberrations in an input beam. This wavefront characterization is extremely fast as it is based on simple measurements of the intensity of focal spots and does not require any computations. Furthermore, the system does not require a computer in the loop and is thus much cheaper, less complex and more robust as well. A fully functional, closed-loop prototype incorporating a 32-element MEMS mirror has been constructed. The unit has a footprint no larger than a laptop but runs at a bandwidth of 100kHz over an order of magnitude faster than comparable, conventional systems occupying a significantly larger volume. Additionally, since the sensing is based on parallel, all-optical processing, the speed is independent of actuator number running at the same bandwidth for one actuator as for a million. We are developing the HALOS technology with a view towards next-generation surveillance systems for extreme adaptive optics applications. These include imaging, lidar and free-space optical communications for unmanned aerial vehicles and SSA. The small volume is ideal for UAVs, while the high speed and high resolution will be of great benefit to the ground-based observation of space-based objects.

  10. Tomographic diffractive microscopy and multiview profilometry with flexible aberration correction.

    Liu, H; Bailleul, J; Simon, B; Debailleul, M; Colicchio, B; Haeberlé, O

    2014-02-01

    We have developed a tomographic diffractive microscope in reflection, which permits observation of sample surfaces with an improved lateral resolution, compared to a conventional holographic microscope. From the same set of data, high-precision measurements can be performed on the shape of the reflective surface by reconstructing the phase of the diffracted field. Doing so allows for several advantages compared to classical holographic interferometric measurements: improvement in lateral resolution, easier phase unwrapping, reduction of the coherent noise, combined with the high-longitudinal precision provided by interferometric phase measurements. We demonstrate these capabilities by imaging various test samples. PMID:24514193

  11. Nuclear Scans

    Nuclear scans use radioactive substances to see structures and functions inside your body. They use a special ... images. Most scans take 20 to 45 minutes. Nuclear scans can help doctors diagnose many conditions, including ...

  12. Scanning ultrafast electron microscopy

    Yang, Ding-Shyue; Mohammed, Omar F.; Zewail, Ahmed H.

    2010-01-01

    Progress has been made in the development of four-dimensional ultrafast electron microscopy, which enables space-time imaging of structural dynamics in the condensed phase. In ultrafast electron microscopy, the electrons are accelerated, typically to 200 keV, and the microscope operates in the transmission mode. Here, we report the development of scanning ultrafast electron microscopy using a field-emission-source configuration. Scanning of pulses is made in the single-electron mode, for whic...

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

    Wood, A. W.; Babcock, S. E. [Materials Science and Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States); Guan, Y.; Forghani, K.; Anand, A.; Kuech, T. F. [Chemical and Biological Engineering, University of Wisconsin-Madison, Madison, Wisconsin 53706 (United States)

    2015-03-01

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

  14. Imaging the surface morphology, chemistry and conductivity of LiNi1/3Fe1/3Mn4/3O4 crystalline facets using scanning transmission X-ray microscopy.

    Zhou, Jigang; Wang, Jian; Cutler, Jeffrey; Hu, Enyuan; Yang, Xiao-Qing

    2016-08-17

    Scanning transmission X-ray microscopy (STXM) using the X-ray fluorescence mode has been employed to elucidate the chemical structures at Ni, Fe, Mn and O sites from the (111) and (100) facets of micron-sized LiNi1/3Fe1/3Mn4/3O4 energy material particles. Furthermore, STXM imaging using electron yield mode has mapped out the surface conductivity of the crystalline particles. This study presents a novel approach that visualizes local element segregation, chemistry and conductivity variation among different crystal facets, which will assist further tailoring of the morphology and surface structure of this high voltage spinel lithium ion battery cathode material. PMID:27491629

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

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

  16. Morphological and ultrastructural characterization of ionoregulatory cells in the teleost Oreochromis niloticus following salinity challenge combining complementary confocal scanning laser microscopy and transmission electron microscopy using a novel prefixation immunogold labeling technique.

    Fridman, Sophie; Rana, Krishen J; Bron, James E

    2013-10-01

    Aspects of ionoregulatory or mitochondria-rich cell (MRC) differentiation and adaptation in Nile tilapia yolk-sac larvae following transfer from freshwater to elevated salinities, that is, 12.5 and 20 ppt are described. Investigations using immunohistochemistry on whole-mount Nile tilapia larvae using anti- Na⁺/K⁺-ATPase as a primary antibody and Fluoronanogold™ (Nanoprobes) as a secondary immunoprobe allowed fluorescent labeling with the high resolution of confocal scanning laser microscopy combined with the detection of immunolabeled target molecules at an ultrastructural level using transmission electron microscopy (TEM). It reports, for the first time, various developmental stages of MRCs within the epithelial layer of the tail of yolk-sac larvae, corresponding to immature, developing, and mature MRCs, identifiable by their own characteristic ultrastructure and form. Following transfer to hyperosmotic salinities the density of immunogold particles and well as the intricacy of the tubular system appeared to increase. In addition, complementary confocal scanning laser microscopy allowed identification of immunopositive ramifying extensions that appeared to emanate from the basolateral portion of the cell that appeared to be correlated with the localization of subsurface tubular areas displaying immunogold labeled Na⁺/K⁺-ATPase. This integrated approach describes a reliable and repeatable prefixation immunogold labeling technique allowing precise visualization of NaK within target cells combined with a 3D imaging that offers valuable insights into MRC dynamics at an ultrastructural level. PMID:23873584

  17. CT Scans

    ... cross-sectional pictures of your body. Doctors use CT scans to look for Broken bones Cancers Blood clots Signs of heart disease Internal bleeding During a CT scan, you lie still on a table. The table ...

  18. Thyroid scan

    ... PET scan Skin nodules Thyroid cancer Thyroid cancer - medullary carcinoma Thyroid cancer - papillary carcinoma Toxic nodular goiter ... Topics Hyperthyroidism Hypothyroidism Nuclear Scans Thyroid Cancer Thyroid Diseases Thyroid Tests Browse the Encyclopedia A.D.A. ...

  19. Analysis of self-organized In(Ga)As quantum structures with the scanning transmission electron microscope; Analyse selbstorganisierter In(Ga)As-Quantenstrukturen mit dem Raster-Transmissionselektronenmikroskop

    Sauerwald, Andres

    2008-05-27

    Aim of this thesis was to apply the analytical methods of the scanning transmission electron microscopy to the study of self-organized In(Ga)As quantum structures. With the imaging methods Z contrast and bright field (position resolutions in the subnanometer range) and especially with the possibilities of the quantitative chemical EELS analysis of the scanning transmission electron microscope (STEM) fundamental questions concerning morphology and chemical properties of self-organized quantum structures should be answered. By the high position resolution of the STEM among others essentail morphological and structural parameters in the growth behaviour of 'dot in a well' (DWell) structures and of vertically correlated quantum dots (QDs) could be analyzed. For the optimization of DWell structures samples were studied, the nominal InAs-QD growth position was directedly varied within the embedding InGaAs quantum wells. The STEM offers in connection with the EELS method a large potential for the chemical analysis of quantum structures. Studied was a sample series of self-organized InGaAs/GaAs structures on GaAs substrate, the stress of which was changed by varying the Ga content of the INGaAs material between 2.4 % and 4.3 %. [German] Ziel dieser Arbeit war es, die analytischen Methoden der Raster-Transmissionselektronenmikroskopie zur Untersuchung selbstorganisierter In(Ga)As-Quantenstrukturen anzuwenden. Mit den abbildenden Methoden Z-Kontrast und Hellfeld (Ortsaufloesungen im Subnanometerbereich) und insbesondere mit den Moeglichkeiten der quantitativen chemischen EELS-Analyse des Raster-Transmissionselektronenmikroskops (RTEMs) sollten grundsaetzliche Fragestellungen hinsichtlich der Morphologie und der chemischen Eigenschaften selbstorganisierter Quantenstrukturen beantwortet werden. Durch die hohe Ortsaufloesung des RTEMs konnten u.a. essentielle morphologische und strukturelle Parameter im Wachstumsverhalten von 'Dot in a Well

  20. Scanning transmission low-energy electron microscopy

    Müllerová, Ilona; Hovorka, Miloš; Konvalina, Ivo; Unčovský, M.; Frank, Luděk

    2011-01-01

    Roč. 55, č. 4 (2011), 2:1-6. ISSN 0018-8646 R&D Projects: GA AV ČR IAA100650902; GA MŠk ED0017/01/01 Institutional research plan: CEZ:AV0Z20650511 Keywords : TEM * STEM * SEM Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering Impact factor: 0.723, year: 2011

  1. Scanning transmission electron microscopy imaging and analysis

    Pennycook, Stephen J

    2011-01-01

    Provides the first comprehensive treatment of the physics and applications of this mainstream technique for imaging and analysis at the atomic level Presents applications of STEM in condensed matter physics, materials science, catalysis, and nanoscience Suitable for graduate students learning microscopy, researchers wishing to utilize STEM, as well as for specialists in other areas of microscopy Edited and written by leading researchers and practitioners

  2. CT scan

    ... come from a CT scan. Some people have allergies to contrast dye. Let your doctor know if you have ... vein contains iodine. If you have an iodine allergy, a type of contrast may cause nausea or vomiting , sneezing , itching , or ...

  3. MRI Scans

    Magnetic resonance imaging (MRI) uses a large magnet and radio waves to look at organs and structures inside your body. Health care professionals use MRI scans to diagnose a variety of conditions, from ...

  4. Scanning transmission electron microscopy (STEM) study on surface modified CVD diamond/Si(111) film post implanted Fe-B and NiFe-B related to GMR properties

    Purwanto, Setyo; Iskandar, R.; Dimyati, A.

    2016-04-01

    Nanostructure investigation on the post implantation by Fe-B and NiFe-B on CVD diamond/Si(111) film have been studied by means of STEM related to their GMR phenomena. Two samples were investigated carefully, firstly sample is post NiFe-B at E=70keV and dose= 1015 ions/cm2 (denoted as A-E3D1). Secondly, is post FeB at E=20 keV and dose= 1015 ions/cm2 (denoted as B-E1D1). Based on FPP measurement at room temperature (RT) and Happlied = 8 kOe, A-E3D1 sample has MR ratio almost 80% and MR ratio in B-E1D1 sample is 45%. Based on STEM-EDX investigation, there are two aspects of how MR ratio of A-E3D1 more higher than those of B-E1D1. Firstly, surface nanostructure on the top of A-E3D1 film is more grazing than on the top of B-E1D1. Analysis with Scanning Transmission Electron Microscope (STEM) equipped with Electron Energy Loss Spectroscopy (EELS) the growth of amorphous carbon layer on top of the implanted diamond film with thickness around 100 nm and only 20 nm on the no implanted sample have observed. Boron atoms were found inside the carbon amorphous layer distributed homogenously. Secondly, oxygen content at the interface between diamond film and silicon substrate in sample A-E3D1 was lower than those in B-E1D1 sample. This condition gives the resistance value in A-E3D1 lower than value in B-E1D1. This result is close to the Raman Spectroscopy data measurement which obviously suggests changes on the Raman spectrum due to implantation related to Oxygen excitation from B-E1D1 sample.

  5. In Situ Transmission Electron Microscopy And Spectroscopy Studies Of Rechargeable Batteries Under Dynamic Operating Conditions: A Retrospective And Perspective View

    Wang, Chong M.

    2015-02-14

    Since the advent of the transmission electron microscope (TEM), continuing efforts have been made to image material under native and reaction environments that typically involve liquids, gases, and external stimuli. With the advances of aberration-corrected TEM for improving the imaging resolution, steady progress has been made on developing methodologies that allow imaging under dynamic operating conditions, or in situ TEM imaging. The success of in situ TEM imaging is closely associated with advances in microfabrication techniques that enable manipulation of nanoscale objects around the objective lens of the TEM. This paper summarizes and highlights recent progress involving in situ TEM studies of energy storage materials, especially rechargeable batteries. The paper is organized to cover both the in situ TEM techniques and the scientific discoveries made possible by in situ TEM imaging.

  6. Scan Statistics

    Glaz, Joseph

    2009-01-01

    Suitable for graduate students and researchers in applied probability and statistics, as well as for scientists in biology, computer science, pharmaceutical science and medicine, this title brings together a collection of chapters illustrating the depth and diversity of theory, methods and applications in the area of scan statistics.

  7. Three-Dimensional Structural Analysis of MgO-Supported Osmium Clusters by Electron Microscopy with Single-Atom Sensitivity

    Aydin, C.; Kulkarni, Apoorva; Chi, Miaofang; Browning, Nigel D.; Gates, Bruce C.

    2013-05-10

    Size, shape, nuclearity: Aberration-corrected scanning transmission electron microscopy was used to determine the 3D structures of MgO-supported Os3, Os4, Os5, and Os10 clusters, which have structures nearly matching those of osmium carbonyl compounds with known crystal structures. The samples are among the best-defined supported catalysts.

  8. Thyroid Scan and Uptake

    ... News Physician Resources Professions Site Index A-Z Thyroid Scan and Uptake Thyroid scan and uptake uses ... the Thyroid Scan and Uptake? What is a Thyroid Scan and Uptake? A thyroid scan is a ...

  9. Pelvic CT scan

    ... axial tomography scan - pelvis; Computed tomography scan - pelvis; CT scan - pelvis ... Risks of CT scans include: Being exposed to radiation Allergic reaction to contrast dye CT scans do expose you to more radiation ...

  10. Cervical spine CT scan

    ... cervical spine; Computed tomography scan of cervical spine; CT scan of cervical spine; Neck CT scan ... Risks of CT scans include: Being exposed to radiation Allergic reaction to contrast dye CT scans expose you to more radiation than ...

  11. Sinus CT scan

    ... axial tomography scan - sinus; Computed tomography scan - sinus; CT scan - sinus ... Risks of a CT scan includes: Being exposed to radiation Allergic reaction to contrast dye CT scans expose you to more radiation than regular ...

  12. Transmission issues

    This session on transmission issues focused on the role that transmission plays in electricity markets and the importance of getting the market structure right in terms of generation divestiture with buy back contracts, demand side responsive programs, transmission upgrades and long term contracts. The difficulties of distinguishing between market power and scarcity were examined along with some of the complications that ensue if transmission experiences congestion, as exemplified by the August 2003 blackout in eastern North America. The presentations described the best ways to handle transmission issues, and debated whether transmission should be deregulated or follow market forces. Issues of interconnections and reliability of connections were also debated along with the attempt to integrate renewables into the grid. Some presentations identified what new transmission must be built and what must be done to ensure that transmission gets built. The challenges and business opportunities for transmission in Alberta were discussed with reference to plans to invest in new infrastructure, where it is going outside of the province and how it works with other jurisdictions. Manitoba's Conawapa Hydro Project and its 2000 MW tie line to Ontario was also discussed. Some examples of non-optimal use of interconnections in Europe were also discussed in an effort to learn from these mistakes and avoid them in Canada. tabs., figs

  13. Scanning electron microscopy - application and techniques

    The application of the scanning electron microscope, and other image forming scanning systems (STEM and the nuclear microprobe), to a range of nuclear reactor problems is described. Particular attention is given to the solution of fracture problems. Autoradiography, electron spectroscopy, and an investigation of irradiation damage in boron carbide using the transmission electron microscope are also described. (author)

  14. Abdominal CT scan

    Computed tomography scan - abdomen; CT scan - abdomen; CAT scan - abdomen; CT abdomen and pelvis ... An abdominal CT scan makes detailed pictures of the structures inside your belly (abdomen) very quickly. This test may be used to ...

  15. Shoulder CT scan

    CAT scan - shoulder; Computed axial tomography scan - shoulder; Computed tomography scan - shoulder; CT scan - shoulder ... stopping.) A computer creates separate images of the shoulder area. These are called slices. These images can ...

  16. High Speed, Radiation Hard CMOS Pixel Sensors for Transmission Electron Microscopy

    Contarato, Devis; Denes, Peter; Doering, Dionisio; Joseph, John; Krieger, Brad

    CMOS monolithic active pixel sensors are currently being established as the technology of choice for new generation digital imaging systems in Transmission Electron Microscopy (TEM). A careful sensor design that couples μm-level pixel pitches with high frame rate readout and radiation hardness to very high electron doses enables the fabrication of direct electron detectors that are quickly revolutionizing high-resolution TEM imaging in material science and molecular biology. This paper will review the principal characteristics of this novel technology and its advantages over conventional, optically-coupled cameras, and retrace the sensor development driven by the Transmission Electron Aberration corrected Microscope (TEAM) project at the LBNL National Center for Electron Microscopy (NCEM), illustrating in particular the imaging capabilities enabled by single electron detection at high frame rate. Further, the presentation will report on the translation of the TEAM technology to a finer feature size process, resulting in a sensor with higher spatial resolution and superior radiation tolerance currently serving as the baseline for a commercial camera system.

  17. HIV Transmission

    ... Abroad Treatment Basic Statistics Get Tested Find an HIV testing site near you. Enter ZIP code or city Follow HIV/AIDS CDC HIV CDC HIV/AIDS See RSS | ... on HIV Syndicated Content Website Feedback HIV/AIDS HIV Transmission Language: English Español (Spanish) Recommend on Facebook ...

  18. Head CT scan

    Brain CT; Cranial CT; CT scan - skull; CT scan - head; CT scan - orbits; CT scan - sinuses; Computed tomography - cranial ... The x-rays produced by the CT scan are painless. Some people may ... hard table. Contrast given through a vein may cause a: Slight ...

  19. RBC nuclear scan

    An RBC nuclear scan uses small amounts of radioactive material to mark (tag) red blood cells (RBCs). Your body is then ... scanner does not give off any radiation. Most nuclear scans (including an RBC scan) are not recommended ...

  20. Heart PET scan

    ... nuclear medicine scan; Heart positron emission tomography; Myocardial PET scan ... A PET scan requires a small amount of radioactive material (tracer). This tracer is given through a vein (IV), ...

  1. Coronary Calcium Scan

    ... the NHLBI on Twitter. What Is a Coronary Calcium Scan? A coronary calcium scan is a test ... you have calcifications in your coronary arteries. Coronary Calcium Scan Figure A shows the position of the ...

  2. Scan BIST with biased scan test signals

    XIANG Dong; CHEN MingJing; SUN JiaGuang

    2008-01-01

    The conventional test-per-scan built-in self-test (BIST) scheme needs a number of shift cycles followed by one capture cycle.Fault effects received by the scan flip-flops are shifted out while shifting in the next test vector like scan testing.Unlike deterministic testing,it is unnecessary to apply a complete test vector to the scan chains.A new scan-based BIST scheme is proposed by properly controlling the test signals of the scan chains,Different biased random values are assigned to the test signals of scan flip-flops in separate scan chains.Capture cycles can be inserted at any clock cycle if necessary.A new testability estimation procedure according to the proposed testing scheme is presented.A greedy procedure is proposed to select a weight for each scan chain.Experimental results show that the proposed method can improve test effectiveness of scan-based BIST greatly,and most circuits can obtain complete fault coverage or very close to complete fault coverage.

  3. LANL Robotic Vessel Scanning

    Webber, Nels W. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2015-11-25

    Los Alamos National Laboratory in J-1 DARHT Operations Group uses 6ft spherical vessels to contain hazardous materials produced in a hydrodynamic experiment. These contaminated vessels must be analyzed by means of a worker entering the vessel to locate, measure, and document every penetration mark on the vessel. If the worker can be replaced by a highly automated robotic system with a high precision scanner, it will eliminate the risks to the worker and provide management with an accurate 3D model of the vessel presenting the existing damage with the flexibility to manipulate the model for better and more in-depth assessment.The project was successful in meeting the primary goal of installing an automated system which scanned a 6ft vessel with an elapsed time of 45 minutes. This robotic system reduces the total time for the original scope of work by 75 minutes and results in excellent data accumulation and transmission to the 3D model imaging program.

  4. Transcending Transmission

    Schoeneborn, Dennis; Trittin, Hannah

    2013-01-01

    Purpose – Extant research on corporate social responsibility (CSR) communication primarily relies on a transmission model of communication that treats organizations and communication as distinct phenomena. This approach has been criticized for neglecting the formative role of communication in the....... Organizations are stabilized by various non-human entities that “act” on their behalf. Accordingly, CSR communication should also take into account non-human agency and responsibility. Originality/value – This paper links the literature on CSR communication to broader debates in organizational communication...... studies and, in particular, to the CCO perspective. By applying the CCO view, it reconceptualizes CSR communication as a complex process of meaning negotiation....

  5. Fiber coupled ultrafast scanning tunneling microscope

    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...

  6. Methods of automatic scanning of SSNTDs

    The methods of automatic scanning of solid state nuclear track detectors are reviewed. The paper deals with transmission of light, charged particles, chemicals and electrical current through conventionally etched detectors. Special attention is given to the jumping spark technique and breakdown counters. Eventually optical automatic devices are examined. (orig.)

  7. Rapid Frequency Scan EPR

    Tseitlin, Mark; Rinard, George A.; Quine, Richard W.; Eaton, Sandra S.; Eaton, Gareth R.

    2011-01-01

    In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x,y plane decays to baseline at the end of the scan, which typically is about 5 T2 after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5 T2. However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded...

  8. Quantification of repositioning errors in PET-studies through superposition of emission and transmission scan. A comparison between one-step and two-step acquisitions; Quantifizierung von Repositionierungsfehlern bei PET-Studien durch Ueberlagerung von Emissions- und Transmissionsscan. Ein Vergleich zwischen Akquisitionen mit und ohne Repositionierung

    Reinartz, P.; Zimny, M.; Cremerius, U.; Sabri, O.; Kaiser, H.J.; Nowak, B.; Buell, U. [Technische Hochschule Aachen (Germany). Klinik fuer Nuklearmedizin

    1999-07-01

    Aim: The purpose of this study was to quantify positioning discrepancies between emission (E) and transmission (T) scan using image fusion. A direct comparison of one-step and two-step acquisitions was performed where all studies were analyzed in respect to artifacts caused by inaccurate positioning. In addition, phantom measurements were conducted to estimate the consequences of repositioning errors on standardized uptake value calculations (SUV). Methods: 40 patients were examined by two-step whole-body scans using PET and 15 patients were subject to one-step examinations in the head/neck area. Repositioning between the scans was achieved by a laser matrix positioning system in combination with external body markings. After reconstruction and image fusion of the scans, the positioning discrepancies were measured as the distances between the outer boundaries of E and T in four different body regions. Additional evaluations of the SUV by increasing E-T dislocation were performed using a Jaszczak phantom containing hollow spheres. Results: For the two-step acquisitions, the mean spatial deviations along the three orthogonal axes x, y, and z were between 8.9 mm and 13.8 mm, whereas for the one-step examinations mean values between 3.5 mm and 4.3 mm were determined (level of siginifance in each direction p<0.0001). Artifacts were found in 47.5% of the whole body scans, but in none of the head/neck studies. The development of image artifacts was simulated by phantom studies. In contrast, the deviations of the computed SUV caused by increasing positioning discrepancies were minimal because of the minimal differences between the attenuation coefficients of the media involved. (orig.) [German] Ziel: Ziel dieser Studie war die Quantifizierung von Lagerungsdiskrepanzen zwischen Emissions- (E) und Transmissionsscan (T) anhand von Fusionsbildern, wobei ein direkter Vergleich zwischen Akquisitionen mit (zweizeitig) und ohne (einzeitig) Patientenrepositionierung erfolgte

  9. Metamaterial-inspired miniaturized microwave edge coupled surface scanning probe

    Wiwatcharagoses, Nophadon; Park, Kyoung Y.; Chahal, Premjeet; Udpa, Lalita

    2013-01-01

    This paper introduces a new concept on sub-wavelength resolution imaging and surface scanning using metamaterial based near field sensor array. Multiple split ring resonator structures (SRRs), having different band stop frequencies, are implemented in a microstrip transmission line configuration. A mirror image copy of these resonators is also incorporated on the transmission line to achieve built in frequency references. A smart card is scanned to detect buried antenna and Si chip within the plastic card.

  10. Lung PET scan

    Chest PET scan; Lung positron emission tomography; PET - chest; PET - lung; PET - tumor imaging ... A PET scan requires a small amount of tracer. The tracer is given through a vein (IV), usually on ...

  11. RBC nuclear scan

    ... page: //medlineplus.gov/ency/article/003835.htm RBC nuclear scan To use the sharing features on this page, please enable JavaScript. An RBC nuclear scan uses small amounts of radioactive material to ...

  12. Atlas of duplex scanning

    This book presents the first atlas devoted entirely to duplex scanning. It details the uses of this important ''up-and-coming'' diagnostic tool for vascular and general surgeons and radiologists. It also covers scanning of the extremities, as well as the carotoids. The topics also covered are correlative line drawings elaborate and clarify the excellent scan images; the principles of duplex scanning or arteries and veins, techniques, and results; pictures normal anatomy; venous thromboses, arterial occlusion, true and false aneurysms, graft stenoses

  13. MULTISCALE GUIDED DEBLURRING: CHROMATIC ABERRATION CORRECTION IN COLOR AND NEAR-INFRARED IMAGING

    Sadeghipoor Kermani, Zahra; Lu, Yue; Mendez, Erick; Süsstrunk, Sabine

    2015-01-01

    Chromatic aberration, caused by photographic lens imperfections, results in the image of only one spectral channel being sharp, while the other channels are blurred depending on their wavelengths difference with the sharp channel. We study chromatic aberration for a system that jointly records color and near-infrared (NIR) images on a single sensor. Chromatic aberration in such a system leads to a blurred NIR image when the color image is in-focus and sharp. We propose an algorithm that deblu...

  14. Sub-Angstrom resolution with aberration-corrected TEM: Present and future

    O' Keefe, Michael A.

    2004-07-01

    Resolution is the ability to determine if a feature in an image represents two objects rather than one. Rayleigh's resolution criterion, an accepted standard in optics, was derived as a means for judging when two sources of light (stars) were distinguishable from a single source. In microscopy, resolution is the ability to determine if detail in an image represents distinct (separated) objects. In high-resolution TEM, these objects are atoms. Resolution of |d| is achieved when atoms separated by a (projected) distance |d| can be perceived as separate objects. TEM images are able to depict projected atom columns because they are interference patterns of the directly transmitted electron beam with beams diffracted from the specimen imaged under well-established conditions.

  15. In-flight aberrations corrections for large space telescopes using active optics

    Laslandes, M.; Ferrari, M.; Hugot, E.; Lemaitre, G.

    2010-07-01

    The need for both high quality images and light structures is a constant concern in the conception of space telescopes. The goal here is to determine how an active optics system could be embarked on a satellite in order to correct the wave front deformations of the optical train. The optical aberrations appearing in a space environment are due to mirrors' deformations, with three main origins: the thermal variations, the weightlessness in space with respect to the Assemblage, Integration and Testing (AIT) conditions on ground and the use of large weightlighted primary mirrors. We are developing a model of deformable mirror as minimalist as possible, especially in term of number of actuators, which is able to correct the first Zernike polynomials in the specified range of amplitude and precision. Flight constraints as weight, volume and power consumption have to be considered. Firstly, such a system is designed according to the equations from the elasticity theory: we determine the geometrical and mechanical characteristics of the mirror, the location of the forces to be applied and the way to apply them. The concept is validated with a Finite Element Analysis (FEA), allowing optimizing the system by taking into account parameters absent from the theory. At the end of the program the mirror will be realized and characterized in a representative optical configuration.

  16. The Compact Hyperspectral Aberration-corrected Platform (CHAP), an instrument for microspacecraft. Project

    National Aeronautics and Space Administration — In-situ analysis of solar system bodies plays a crucial role in understanding the evolution of our planet, setting the stage for life's origins. As has been...

  17. Holographic Properties of BR-D96N Film and Its Application in Hologram Aberration Correction

    ZHENG Yuan(郑媛); YAO Bao-Li(姚保利); WANG Ying-Li(王英利); MENKE Neimule(门克内木乐); LEI Ming(雷铭); CHEN Guo-Fu(陈国夫); Norbert HAMPP

    2003-01-01

    A biophotochromic material, i.e., genetic mutant bacteriorhodopsin (BR-D96N), was experimentally studied on its holographic recording properties. The saturation absorption curve and the diffraction efficiency curve were measured respectively. As holographic storage application, reflection type polarization holograms were recorded on the BR-D96N film. The 173° configuration between the object and reference beams proves that the spatial resolution of the film is over 6000 lines/mm. By using phase conjugate wave of reference beam as reconstruction beam, the distorted object image introduced by the optical components and the defects in the recording medium can be well corrected.

  18. Canopy induced aberration correction in airborne electro-optical imaging systems

    Harder, James A.; Sprague, Michaelene W.

    2011-11-01

    An increasing number of electro-optical systems are being used by pilots in tactical aircraft. This means that the afore mentioned systems must operate through the aircrafts canopy, unfortunately the canopy functions as a less than ideal lens element in the electro-optical sensor optical path. The canopy serves first and foremost as an aircraft structural component, considerations like minimizing the drag co-efficient and the ability to survive bird strikes take precedence over achieving optimal optical characteristics. This paper describes how the authors characterized the optical characteristics of an aircraft canopy. Families of modulation transfer functions were generated, for various viewing geometries through the canopy and for various electro-optical system entrance pupil diameters. These functions provided us with the means to significantly reduce the effect of the canopy "lens" on the performance of a representative electro-optical system, using an Astigmatic Corrector Lens. A comparison of the electro-optical system performance with and without correction is also presented.

  19. Chromatic aberration correction and deconvolution for UV sensitive imaging of fluorescent sterols in cytoplasmic lipid droplets

    Wüstner, Daniel; Faergeman, Nils J

    2008-01-01

    Intrinsically fluorescent sterols, like dehydroergosterol (DHE), mimic cholesterol closely and are therefore suitable to determine cholesterol transport by fluorescence microscopy. Disadvantages of DHE are its low quantum yield, rapid bleaching, and the fact that its excitation and emission is in...

  20. A Successive Scans Method of Adjusting Scan-Time for Injection Electroluminescent Display Panels

    OU Peng; YANG Gang; JIANG Quan; WANG Jun; HU Jian-Hua; WU Qi-Peng; LUO Kai-Jun

    2011-01-01

    @@ Aiming at the problem of luminance uniformity for injection electroluminescent display panels, we present a new scan method for display panels according to successive scans theory.First, on the basis of the number of pixels requiring light emitting in one frame period, we adjust the scan time for each row.Secondly, for ensuring image transmission synchronization, the frame period must to be a constant.We adopt a 64 × 32 LED display panel as an example to expound the new scan method and we obtain the good result that the reduce amplitude of luminance non-uniformity is 31.34% and the increase amplitude of the average luminance value is 7.8258%.%Aiming at the problem of luminance uniformity for injection electroluminescent display panels,we present a new scan method for display panets according to successive scans theory.First,on the basis of the number of pixels requiring light emitting in one frame period,we adjust the scan time for each row.Secondly,for ensuring image transmission synchronization,the frame period must to be a constant.We adopt a 64×32 LED display panel as an example to expound the new scan method and we odtain the good result that the reduce amplitude of luminance non-uniformity is 31.34% and the increase amplitude of the average luminance value is 7.8258%.

  1. Pulmonary ventilation/perfusion scan

    V/Q scan; Ventilation/perfusion scan; Lung ventilation/perfusion scan ... A pulmonary ventilation/perfusion scan is actually two tests. They may be done separately or together. During the perfusion scan, a health ...

  2. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography.

    Jesse, S; Chi, M; Belianinov, A; Beekman, C; Kalinin, S V; Borisevich, A Y; Lupini, A R

    2016-01-01

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called "big-data" methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy. PMID:27211523

  3. Applications of orientation mapping by scanning and transmission electron microscopy

    Juul Jensen, D.

    1997-01-01

    , focus is on cold deformation and recrystallization processes. It is described how the OIM techniques may be applied for studies of such processes. Results of OIM measurements supplement more traditional TEM and SEM microstructure characterizations as well as bulk texture measurements, and new...

  4. Big Data Analytics for Scanning Transmission Electron Microscopy Ptychography

    Jesse, S.; Chi, M.; Belianinov, A.; Beekman, C.; Kalinin, S. V.; Borisevich, A. Y.; Lupini, A. R.

    2016-05-01

    Electron microscopy is undergoing a transition; from the model of producing only a few micrographs, through the current state where many images and spectra can be digitally recorded, to a new mode where very large volumes of data (movies, ptychographic and multi-dimensional series) can be rapidly obtained. Here, we discuss the application of so-called “big-data” methods to high dimensional microscopy data, using unsupervised multivariate statistical techniques, in order to explore salient image features in a specific example of BiFeO3 domains. Remarkably, k-means clustering reveals domain differentiation despite the fact that the algorithm is purely statistical in nature and does not require any prior information regarding the material, any coexisting phases, or any differentiating structures. While this is a somewhat trivial case, this example signifies the extraction of useful physical and structural information without any prior bias regarding the sample or the instrumental modality. Further interpretation of these types of results may still require human intervention. However, the open nature of this algorithm and its wide availability, enable broad collaborations and exploratory work necessary to enable efficient data analysis in electron microscopy.

  5. Rapid frequency scan EPR.

    Tseitlin, Mark; Rinard, George A; Quine, Richard W; Eaton, Sandra S; Eaton, Gareth R

    2011-08-01

    In rapid frequency scan EPR with triangular scans, sufficient time must be allowed to insure that the magnetization in the x, y plane decays to baseline at the end of the scan, which typically is about 5T(2) after the spins are excited. To permit relaxation of signals excited toward the extremes of the scan the total scan time required may be much longer than 5T(2). However, with periodic, saw-tooth excitation, the slow-scan EPR spectrum can be recovered by Fourier deconvolution of data recorded with a total scan period of 5T(2), even if some spins are excited later in the scan. This scan time is similar to polyphase excitation methods. The peak power required for either polyphase excitation or rapid frequency scans is substantially smaller than for pulsed EPR. The use of an arbitrary waveform generator (AWG) and cross loop resonator facilitated implementation of the rapid frequency scan experiments reported here. The use of constant continuous low B(1), periodic excitation waveform, and constant external magnetic field is similar to polyphase excitation, but could be implemented without the AWG that is required for polyphase excitation. PMID:21664848

  6. Line-scanning, stage scanning confocal microscope

    Carucci, John A.; Stevenson, Mary; Gareau, Daniel

    2016-03-01

    We created a line-scanning, stage scanning confocal microscope as part of a new procedure: video assisted micrographic surgery (VAMS). The need for rapid pathological assessment of the tissue on the surface of skin excisions very large since there are 3.5 million new skin cancers diagnosed annually in the United States. The new design presented here is a confocal microscope without any scanning optics. Instead, a line is focused in space and the sample, which is flattened, is physically translated such that the line scans across its face in a direction perpendicular to the line its self. The line is 6mm long and the stage is capable of scanning 50 mm, hence the field of view is quite large. The theoretical diffraction-limited resolution is 0.7um lateral and 3.7um axial. However, in this preliminary report, we present initial results that are a factor of 5-7 poorer in resolution. The results are encouraging because they demonstrate that the linear array detector measures sufficient signal from fluorescently labeled tissue and also demonstrate the large field of view achievable with VAMS.

  7. Miniature rotating transmissive optical drum scanner

    Lewis, Robert (Inventor); Parrington, Lawrence (Inventor); Rutberg, Michael (Inventor)

    2013-01-01

    A miniature rotating transmissive optical scanner system employs a drum of small size having an interior defined by a circumferential wall rotatable on a drum axis, an optical element positioned within the interior of the drum, and a light-transmissive lens aperture provided at an angular position in the circumferential wall of the drum for scanning a light beam to or from the optical element in the drum along a beam azimuth angle as the drum is rotated. The miniature optical drum scanner configuration obtains a wide scanning field-of-view (FOV) and large effective aperture is achieved within a physically small size.

  8. Radionucleotide scanning in osteomyelitis

    Radionucleotide bone scanning can be an excellent adjunct to the standard radiograph and clinical findings in the diagnosis of osteomyelitis. Bone scans have the ability to detect osteomyelitis far in advance of the standard radiograph. The sequential use of technetium and gallium has been useful in differentiating cellulitis and osteomyelitis. Serial scanning with technetium and gallium may be used to monitor the response of osteomyelitis to antibiotic therapy

  9. Spectrally encoded confocal scanning laser ophthalmoscope

    Tao, Yuankai K.; Izatt, Joseph A.

    2010-02-01

    Fundus imaging has become an essential clinical diagnostic tool in ophthalmology. Current generation scanning laser ophthalmoscopes (SLO) offer advantages over conventional fundus photography and indirect ophthalmoscopy in terms of light efficiency and contrast. As a result of the ability of SLO to provide rapid, continuous imaging of retinal structures and its versatility in accommodating a variety of illumination wavelengths, allowing for imaging of both endogenous and exogenous fluorescent contrast agents, SLO has become a powerful tool for the characterization of retinal pathologies. However, common implementations of SLO, such as the confocal scanning laser ophthalmoscope (CSLO) and line-scanning laser ophthalmoscope (LSLO), require imaging or multidimensional scanning elements which are typically implemented in bulk optics placed close to the subject eye. Here, we apply a spectral encoding technique in one dimension combined with single-axis lateral scanning to create a spectrally encoded confocal scanning laser ophthalmoscope (SECSLO) which is fully confocal. This novel implementation of the SLO allows for high contrast, high resolution in vivo human retinal imaging with image transmission through a single-mode optical fiber. Furthermore, the scanning optics are similar and the detection engine is identical to that of current-generation spectral domain optical coherence tomography (SDOCT) systems, potentially allowing for a simplistic implementation of a joint SECSLO-SDOCT imaging system.

  10. Dynamic environmental transmission electron microscopy observation of platinum electrode catalyst deactivation in a proton-exchange-membrane fuel cell

    Spherical-aberration-corrected environmental transmission electron microscopy (AC-ETEM) was applied to study the catalytic activity of platinum/amorphous carbon electrode catalysts in proton-exchange-membrane fuel cells (PEMFCs). These electrode catalysts were characterized in different atmospheres, such as hydrogen and air, and a conventional high vacuum of 10−5 Pa. A high-speed charge coupled device camera was used to capture real-time movies to dynamically study the diffusion and reconstruction of nanoparticles with an information transfer down to 0.1 nm, a time resolution below 0.2 s and an acceleration voltage of 300 kV. With such high spatial and time resolution, AC-ETEM permits the visualization of surface-atom behaviour that dominates the coalescence and surface-reconstruction processes of the nanoparticles. To contribute to the development of robust PEMFC platinum/amorphous carbon electrode catalysts, the change in the specific surface area of platinum particles was evaluated in hydrogen and air atmospheres. The deactivation of such catalysts during cycle operation is a serious problem that must be resolved for the practical use of PEMFCs in real vehicles. In this paper, the mechanism for the deactivation of platinum/amorphous carbon electrode catalysts is discussed using the decay rate of the specific surface area of platinum particles, measured first in a vacuum and then in hydrogen and air atmospheres for comparison. (paper)

  11. Experimental evaluation of the 'transport-of-intensity' equation for magnetic phase reconstruction in Lorentz transmission electron microscopy.

    Kohn, Amit; Habibi, Avihay; Mayo, Martin

    2016-01-01

    The 'transport-of-intensity' equation (TIE) is a general phase reconstruction methodology that can be applied to Lorentz transmission electron microscopy (TEM) through the use of Fresnel-contrast (defocused) images. We present an experimental study to test the application of the TIE for quantitative magnetic mapping in Lorentz TEM without aberration correction by examining sub-micrometer sized Ni80Fe20 (Permalloy) elements. For a JEOL JEM 2100F adapted for Lorentz microscopy, we find that quantitative magnetic phase reconstructions are possible for defoci distances ranging between approximately 200 μm and 800 μm. The lower limit originates from competing sources of image intensity variations in Fresnel-contrast images, namely structural defects and diffraction contrast. The upper defocus limit is due to a numerical error in the estimation of the intensity derivative based on three images. For magnetic domains, we show quantitative reconstructions of the product of the magnetic induction vector and thickness in element sizes down to approximately 100 nm in lateral size and 5 nm thick resulting in a minimal detection of 5Tnm. Three types of magnetic structures are tested in terms of phase reconstruction: vortex cores, domain walls, and element edges. We quantify vortex core structures at a diameter of 12 nm while the structures of domain walls and element edges are characterized qualitatively. Finally, we show by image simulations that the conclusions of this experimental study are relevant to other Lorentz TEM in which spherical aberration and defocus are dominant aberrations. PMID:26452194

  12. Transmission Scintiphotography and its Applications

    Clear transmission pictures have been obtained of the heart, diaphragm, trachea, and the lungs in both PA and lateral projections, using the scintillation camera and a radioactive source on the opposite side of the patient. Gas within the stomach and bowel is visualized, and contrast media is readily seen in the intestine. Transmission scintiphotos are of use in the interpretation of the conventional emission scintiphotos. For example, transmission pictures define the extent of the lung so that lung perfusion studies can be interpreted properly. They show the position of the diaphragm in liver studies so that space-occupying lesions between the liver and diaphragm can be detected. They are also useful in positioning the heart and lung fields for dynamic tracer studies. tracer studies. The use of transmission scanning with a rectilinear scanner as a means of improving the interpretation of radionuclide emission scans has been reported previously by Kuhl et al. and it has also been used by Anger in the Whole Body Scanner Mark II. To take transmission images with the scintillation camera, a conventional multichannel collimator is placed on the camera and a radiocactive disc source 11 in. in diameter is placed underneath the patient. A second multichannel collimator is placed on top of the source to reduce the radiation dose to the patient. It also reduces the amount of scattered radiation that appears on the pictures. If the disc source contains about 10-20 mCi of 99mTc, transmission pictures can be taken in 1-2 min. The patient receives less than 1 mR/h to a limited area of the body and virtually no irradiation elsewhere. The 140-keV gamma rays from technetium have very little selective absorption in bone, compared to Iower-energy gamma rays and X-rays. They are scattered by all tissues, and therefore are useful for imaging air spaces within the body such as the lungs. Defects in these air spaces, such as large solid space- occupying lesions in the lungs, can also be

  13. Zika and Sexual Transmission

    ... Address What's this? Submit What's this? Submit Button Zika and Sexual Transmission Language: English Español Português ... Healthcare Providers: Sexual Transmission of Zika Basics of Zika Virus and Sex Transmission Zika can be passed ...

  14. Achieving atomic resolution magnetic dichroism by controlling the phase symmetry of an electron probe

    Rusz, Jan; Idrobo, Juan-Carlos; Bhowmick, Somnath

    2014-01-01

    The calculations presented here reveal that an electron probe carrying orbital angular momentum is just a particular case of a wider class of electron beams that can be used to measure electron magnetic circular dichroism (EMCD) with atomic resolution. It is possible to obtain an EMCD signal with atomic resolution by simply breaking the symmetry of the electron probe phase distribution using the aberration-corrected optics of an scanning transmission electron microscope. The required phase di...

  15. Getting a CAT Scan

    Full Text Available ... Snowboarding, Skating Crushes What's a Booger? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A Text Size en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that means ...

  16. Getting a CAT Scan

    Full Text Available ... Here's Help White House Lunch Recipes Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A Text Size en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that means ...

  17. Abdominal CT scan

    ... than regular x-rays. Many x-rays or CT scans over time may increase your risk for cancer. However, the risk from any one scan is small. Talk to your doctor about this risk and the benefit of the test for getting a correct diagnosis ...

  18. Knee CT scan

    Risks of CT scans include: Exposure to radiation Allergy to contrast dye CT scans give off more radiation than ... injected contrast dye. The most common type of contrast contains ... you have this an iodine allergy. If you need to have this kind of ...

  19. Knee CT scan

    A computed tomography (CT) scan of the knee is a test that uses x-rays to take detailed images of the knee. ... A CT scan can quickly create more detailed pictures of the knee than standard x-rays. The test may be ...

  20. Environmental Scanning Report.

    Truckee Meadows Community Coll., Sparks, NV.

    This report describes Truckee Meadows Community College's (Nevada) environmental scanning process and results. The college decided that environmental scanning and forecasting techniques should be used to plan for both short-term and long-term external factors that impact programs, enrollment, and budgets. Strategic goals include: (1) keeping pace…

  1. Getting a CAT Scan

    Full Text Available ... Dictionary of Medical Words En Español What Other Kids Are Reading Movie: Digestive System Winter Sports: Sledding, ... Booger? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A ...

  2. Getting a CAT Scan

    Full Text Available ... Skiing, Snowboarding, Skating Crushes What's a Booger? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A Text Size en español Obtención de ...

  3. Getting a CAT Scan

    Full Text Available ... Crushes What's a Booger? Getting a CAT Scan (Video) KidsHealth > For Kids > Getting a CAT Scan (Video) Print A A A Text Size en español Obtención de una tomografía computada (video) CAT stands for "computerized axial tomography." Translated, that ...

  4. Survey of Transmission Cost Allocation Methodologies for Regional Transmission Organizations

    Fink, S.; Porter, K.; Mudd, C.; Rogers, J.

    2011-02-01

    The report presents transmission cost allocation methodologies for reliability transmission projects, generation interconnection, and economic transmission projects for all Regional Transmission Organizations.

  5. Transmission Kikuchi diffraction and transmission electron forescatter imaging of electropolished and FIB manufactured TEM specimens

    Zieliński, W., E-mail: wiziel@inmat.pw.edu.pl; Płociński, T.; Kurzydłowski, K.J.

    2015-06-15

    We present a study of the efficiency of the utility of scanning electron microscope (SEM)-based transmission methods for characterizing grain structure in thinned bulk metals. Foils of type 316 stainless steel were prepared by two methods commonly used for transmission electron microscopy — double-jet electropolishing and focused ion beam milling. A customized holder allowed positioning of the foils in a configuration appropriate for both transmission electron forward scatter diffraction, and for transmission imaging by the use of a forescatter detector with two diodes. We found that both crystallographic orientation maps and dark-field transmitted images could be obtained for specimens prepared by either method. However, for both methods, preparation-induced artifacts may affect the quality or accuracy of transmission SEM data, especially those acquired by the use of transmission Kikuchi diffraction. Generally, the quality of orientation data was better for specimens prepared by electropolishing, due to the absence of ion-induced damage. - Highlights: • The transmission imaging and diffraction techniques are emerging in scanning electron microscopy (SEM) as promising new field of materials characterization. • The manuscript titled: “Transmission Kikuchi Diffraction and Transmission Electron Forescatter Imaging of Electropolished and FIB Manufactured TEM Specimens” documents how different specimen thinning procedures can effect efficiency of transmission Kikuchi diffraction and transmission electron forescatter imaging. • The abilities to make precision crystallographic orientation maps and dark-field images in transmission was studied on electropolished versus focus ion beam manufactured TEM specimens. • Depending on the need, electropolished and focused ion beam technique may produce suitable specimens for transmission imaging and diffraction in SEM.

  6. Transmission Kikuchi diffraction and transmission electron forescatter imaging of electropolished and FIB manufactured TEM specimens

    We present a study of the efficiency of the utility of scanning electron microscope (SEM)-based transmission methods for characterizing grain structure in thinned bulk metals. Foils of type 316 stainless steel were prepared by two methods commonly used for transmission electron microscopy — double-jet electropolishing and focused ion beam milling. A customized holder allowed positioning of the foils in a configuration appropriate for both transmission electron forward scatter diffraction, and for transmission imaging by the use of a forescatter detector with two diodes. We found that both crystallographic orientation maps and dark-field transmitted images could be obtained for specimens prepared by either method. However, for both methods, preparation-induced artifacts may affect the quality or accuracy of transmission SEM data, especially those acquired by the use of transmission Kikuchi diffraction. Generally, the quality of orientation data was better for specimens prepared by electropolishing, due to the absence of ion-induced damage. - Highlights: • The transmission imaging and diffraction techniques are emerging in scanning electron microscopy (SEM) as promising new field of materials characterization. • The manuscript titled: “Transmission Kikuchi Diffraction and Transmission Electron Forescatter Imaging of Electropolished and FIB Manufactured TEM Specimens” documents how different specimen thinning procedures can effect efficiency of transmission Kikuchi diffraction and transmission electron forescatter imaging. • The abilities to make precision crystallographic orientation maps and dark-field images in transmission was studied on electropolished versus focus ion beam manufactured TEM specimens. • Depending on the need, electropolished and focused ion beam technique may produce suitable specimens for transmission imaging and diffraction in SEM.

  7. Fiber coupled ultrafast scanning tunneling microscope

    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 substrate. By using a firmly attached fiber we achieve an excellent reproducibility and unconstrained positioning of the tip. We observe a transient signal with 2.9 ps pulse width in tunneling mode and 5...

  8. Laser Scanning in Forests

    Håkan Olsson

    2012-09-01

    Full Text Available The introduction of Airborne Laser Scanning (ALS to forests has been revolutionary during the last decade. This development was facilitated by combining earlier ranging lidar discoveries [1–5], with experience obtained from full-waveform ranging radar [6,7] to new airborne laser scanning systems which had components such as a GNSS receiver (Global Navigation Satellite System, IMU (Inertial Measurement Unit and a scanning mechanism. Since the first commercial ALS in 1994, new ALS-based forest inventory approaches have been reported feasible for operational activities [8–12]. ALS is currently operationally applied for stand level forest inventories, for example, in Nordic countries. In Finland alone, the adoption of ALS for forest data collection has led to an annual savings of around 20 M€/year, and the work is mainly done by companies instead of governmental organizations. In spite of the long implementation times and there being a limited tradition of making changes in the forest sector, laser scanning was commercially and operationally applied after about only one decade of research. When analyzing high-ranked journal papers from ISI Web of Science, the topic of laser scanning of forests has been the driving force for the whole laser scanning research society over the last decade. Thus, the topic “laser scanning in forests” has provided a significant industrial, societal and scientific impact. [...

  9. Scanning with Iodine-125

    The use of I125 as I125-iodide for scanning of the thyroid and of thyroid carcinoma métastasés and as I125-labelled Rose Bengal for scanning of the liver has been investigated in our laboratories. In some patients, the thyroid scans and the scans of thyroid carcinoma metastases were repeated with I131. The liver scans were repeated with colloidal Au198. Cold nodules in the thyroid which could not be detected with I131 were clearly seen with I125. Anterior métastasés in the lungs could be differentiated from posterior métastasés with I125, while with I131 this was not possible. Using the same doses of radioactivity the background with I131 was much higher and could not be eliminated, as this would have reduced the counting rate over the lesions to levels which could not be detected. Some of the photoscans and mechanical scans of livers carried out with colloidal Au198 could not be interpreted. However, ''cold'' lesions were clearly seen on the scans of the same livers with I125-labelled Rose Bengal. (author)

  10. Neutron scanning system for nondestructive testing

    Presented are the methods of nondestructive testing, based on neutron passing, outlet from the reactor, through the samples. Considered are possibilities of the neutron-spectrometric method of nondestructive sample analysis. Given is a description of half-automatic neutron scanning system, presupposed for investigation of nonirradiated, as well as irradiated samples. Described are the assemblies of the scanning device, mechanical relative aperture selector and crystalline monochromator for the purposes of nondestructive testing by the neutron-spectrometric method within 0.01-50 eV neutron energy range. The scanning device makes it possible to investigate a sample 1200 mm long and up to 15 mm in diameter with longitudinal transmission step of 0.5 mm and 0.1 mm accuracy of the transverse device. The equipment neutron spectra, measured by division chamber on the mechanical selector and the scaning results on the crystalline monochromator are given for illustrating the device operation

  11. Breast PET scan

    Breast positron emission tomography; PET - breast; PET - tumor imaging - breast ... A PET scan requires a small amount of radioactive material (tracer). This tracer is given through a vein (IV), usually ...

  12. Pediatric CT Scans

    The Radiation Epidemiology Branch and collaborators have initiated a retrospective cohort study to evaluate the relationship between radiation exposure from CT scans conducted during childhood and adolescence and the subsequent development of cancer.

  13. Shoulder MRI scan

    ... finding on an x-ray or bone scan Shoulder pain and fever Decreased motion of the shoulder joint ... of the shoulder joint Shoulder instability Shoulder weakness Shoulder pain and a history of cancer Shoulder pain that ...

  14. Attenuation correction using postinjection transmission measurements for PET; The optimization of measurement conditions

    Oda, Keiichi; Senda, Michio; Toyama, Hinako; Ishii, Kenji (Tokyo Metropolitan Inst. of Gerontology (Japan)); Amano, Masaharu

    1994-01-01

    A new method of PET attenuation using post-injection transmission scan is presented, which is especially useful in [sup 18]F-FDG static studies. The transmission scan is acquired right before the emission scan, which is used to subtract the emission component from the transmission data. When the effect of measurement condition upon the image noise was evaluated with a 20 cm diameter cylindrical phantom, an increase in the injection dose inflated the noise and caused artifacts. There was an optimum dose that minimized the image noise. As the external source activity increased, the image noise decreased, and the optimum dose increases linearly, which enabled estimation of the optimum injection dose under a given external source. When the total (emission plus transmission ) scan time was fixed, longer emission scan resulted in better images than longer transmission scan. (author).

  15. Advanced Network Scanning

    Ashiqur Rahman

    2016-07-01

    Full Text Available Network scanning is à procedure for identifying active hosts on a network, either for the purpose of attacking them or for network security assessment. Scanning procedures, such as ping sweeps and port scans, return information about which IP addresses map to live hosts that are active on the Internet and what services they offer. Another scanning method, inverse mapping, returns information about what IP addresses do not map to live hosts; this enables an attacker to make assumptions about viable addresses. Scanning is one of three components of intelligence gathering for an attacker. In the foot printing phase, the attacker creates a profile of the target organization, with information such as its domain name system (DNS and e-mail servers, and its IP address range. Most of this information is available online. In the scanning phase, the attacker finds information about the specific IP addresses that can be accessed over the Internet, their operating systems, the system architecture, and the services running on each computer. In the enumeration phase, the attacker gathers information such as network user and group names, routing tables, and Simple Network Management Protocol (SNMP data

  16. Bone scanning in osteoporosis

    This paper reports on bone scanning in osteoporosis a diagnosis of osteoporosis most often follows fracture, and clearly this should be confirmed by x-ray. The bone scan therefore does not have an important role to play in the initial diagnosis of osteoporosis. While the exact mechanism by which the 99mTc-labeled diphosphonates localize in the skeleton is not fully understood, it is believed that they adsorb onto bone surfaces most probably via the calcium of hydroxyapatite crystals. Because the major factors that affect adsorption are osteoblastic activity and to a lesser extent skeletal vascularity, it is apparent that a bone scan image presents a functional display of skeletal metabolic activity. However, osteoporosis is a disorder in which gradual change in bone mass may occur over many years and, in keeping with this minor imbalance in skeletal metabolism, the bone scan appearances are usually normal. However, the scan images may appear of poor quality because of relatively low bone uptake of tracer with, on occasion, a washed-out pattern of activity in the axial and appendicular bone. It has been suggested that such a pattern occurs in severe or end-stage osteoporosis caused by markedly reduced osteoblastic activity. If kyphosis is observed on the bone scan or if there appears to be loss of spinal height with proximity of ribs to each other or increased closeness of rib cage to pelvis, then appearances suggest vertebral collapse and would be in keeping with a diagnosis of osteoporosis. Such evidence is, however, indirect and in practice a bone scan is an extremely unreliable means of diagnosing osteoporosis

  17. Bone scan in pediatrics

    In 1984, a survey carried out in 21 countries in Europe showed that bone scintigraphy comprised 16% of all paediatric radioisotope scans. Although the value of bone scans in paediatrics is potentially great, their quality varies greatly, and poor-quality images are giving this valuable technique a bad reputation. The handling of children requires a sensitive staff and the provision of a few simple inexpensive items of distraction. Attempting simply to scan a child between two adult patients in a busy general department is a recipe for an unhappy, uncooperative child with the probable result of poor images. The intravenous injection of isotope should be given adjacent to the gamma camera room, unless dynamic scans are required, so that the child does not associate the camera with the injection. This injection is best carried out by someone competent in paediatric venipunture; the entire procedure should be explained to the child and parent, who should remain with child throughout. It is naive to think that silence makes for a cooperative child. The sensitivity of bone-seeking radioisotope tracers and the marked improvement in gamma camera resolution has allowed the bone scanning to become an integrated technique in the assessment of children suspected of suffering from pathological bone conditions. The tracer most commonly used for routine bone scanning is 99mTc diphosphonate (MDP); other isotopes used include 99mTc colloid for bone marrow scans and 67Ga citrate and 111In white blood cells (111In WBC) for investigation of inflammatory/infective lesions

  18. Lung Ventilation/Perfusion Scan

    ... two types of scans: ventilation and perfusion. The ventilation scan shows where air flows in your lungs. The perfusion scan shows where blood flows in your lungs. Both scans use radioisotopes (a low-risk radioactive substance). For the ventilation scan, you ...

  19. Scanning Probe Microscopy and Spectroscopy

    Wiesendanger, Roland

    1994-09-01

    Preface; List of acronyms; Introduction; Part I. Experimental Methods and Theoretical Background of Scanning Probe Microscopy and Spectroscopy: 1. Scanning tunnelling microscopy; 2. Scanning force microscopy; 3. Related scanning probe techniques; Part II. Applications of Scanning Probe Microscopy and Spectroscopy: 4. Condensed matter physics; 5. Chemistry; 6. Organic materials; 7. Metrology and standards; 8. Nanotechnology; References; Index.

  20. Elemental mapping in achromatic atomic-resolution energy-filtered transmission electron microscopy

    Forbes, B.D. [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia); Houben, L. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Gruenberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Mayer, J. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Gruenberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Central Facility for Electron Microscopy, RWTH Aachen University, D-52074 Aachen (Germany); Dunin-Borkowski, R.E. [Ernst Ruska-Centre for Microscopy and Spectroscopy with Electrons and Peter Gruenberg Institute, Forschungszentrum Jülich, D-52425 Jülich (Germany); Allen, L.J., E-mail: lja@unimelb.edu.au [School of Physics, University of Melbourne, Parkville, VIC 3010 (Australia)

    2014-12-15

    We present atomic-resolution energy-filtered transmission electron microscopy (EFTEM) images obtained with the chromatic-aberration-corrected FEI Titan PICO at the Ernst-Ruska Centre, Jülich, Germany. We find qualitative agreement between experiment and simulation for the background-subtracted EFTEM images of the Ti–L{sub 2,3} and O–K edges for a specimen of SrTiO{sub 3} oriented down the [110] zone axis. The simulations utilize the transition potential formulation for inelastic scattering, which permits a detailed investigation of contributions to the EFTEM image. We find that energy-filtered images of the Ti–L{sub 2,3} and O–K edges are lattice images and that the background-subtracted core-loss maps may not be directly interpretable as elemental maps. Simulations show that this is a result of preservation of elastic contrast, whereby the qualitative details of the image are determined primarily by elastic, coherent scattering. We show that this effect places a constraint on the range of specimen thicknesses which could theoretically yield directly useful elemental maps. In general, interpretation of EFTEM images is ideally accompanied by detailed simulations. - Highlights: • Achromatic atomic-resolution EFTEM images were obtained for STO 〈110〉. • Simulations were in qualitative agreement with Ti–L{sub 2,3} and O–K edge maps. • The experimental EFTEM maps are not directly interpretable as elemental maps. • Image intensities are strongly determined by preservation of elastic contrast. • Interpretation of EFTEM images is ideally accompanied by detailed simulations.

  1. Lung scans and malignancy

    An experience of pulmonary isotope scanning carried out with mercury 197 labelled mercury chloride and acetate, cobalt 57-labelled bleomycin, and Cu67 and Cu64 labelled copper citrate was presented. The scans were carried out with various isotopes supplied by the French Atomic Energy Authority, and gave comparable results, which may be summarised as follows: increased uptake in more than 90% of cases of carcinoma, absent uptake in all cases of benign tumour, frequent increased uptake in acute or advanced inflammatory lesions, absence of uptake, very commonly, in tuberculoma and chronic lesions with scar formation. Radio-isotope scan using Cu67 labelled copper citrate permitted discrimination of malignant tumours (increased fixation which showed up best at the 24th hour) from inflammatory lesions (increased fixation which was reduced on the 24th hour). The positive or negative character of the fixation in a given lesions remains the same, whatever the isotope used in our experience

  2. Merchant Transmission Investment

    Joskow, Paul L.; Tirole, Jean

    2003-01-01

    We examine the performance attributes of a merchant transmission investment framework that relies on ?market driven? transmission investment to provide the infrastructure to support competitive wholesale markets for electricity. Under a stringent set of assumptions, the merchant investment model appears to solve the natural monopoly problem and the associated need for regulating transmission companies traditionally associated with electric transmission networks. We expand the model to inc...

  3. Scanning Electron Microscopy with a Retarded Primary Beam

    Frank, Luděk

    Rijeka: InTech, 2016 - (Janeček, M.; Král, R.), s. 49-78 ISBN 978-953-51-2252-4 R&D Projects: GA TA ČR(CZ) TE01020118; GA MŠk(CZ) LO1212 Institutional support: RVO:68081731 Keywords : scanning electron microscopy * scanning transmission electron microscopy * slow electrons * electron microscopy of materials * biomedical eletron microscopy Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering

  4. Communication line for an image scanning and measurement Complex

    A complex for an on-line processing of the film information obtained in the process of photography of events in a bubble chambers is described. The complex involves an image scanning and measurement apparatus (5 SAMET image scanning and measurement tables and 2 VT-340 alphanumeric displays) the Electronics computer and data transmission line consisting of the communication line itself and two buffer shaping amplifiers and interfaces. The flowsheet of the above complex communication line is presented

  5. Bone scan in rheumatology

    In this chapter a revision is made concerning different uses of bone scan in rheumatic diseases. These include reflex sympathetic dystrophy, osteomyelitis, spondyloarthropaties, metabolic bone diseases, avascular bone necrosis and bone injuries due to sports. There is as well some comments concerning pediatric pathology and orthopedics. (authors). 19 refs., 9 figs

  6. Scanning bubble chamber pictures

    1974-01-01

    These were taken at the 2 m hydrogen bubble chamber. The photo shows an early Shiva system where the pre-measurements needed to qualify the event were done manually (cf photo 7408136X). The scanning tables were located in bld. 12. Gilberte Saulmier sits on foreground, Inge Arents at centre.

  7. Getting a CAT Scan

    Full Text Available ... The scan itself is painless. All you'll need to do is hold still for a few minutes at a time so the pictures come out clear ... the Nemours Web site. Note: All information on KidsHealth® is for educational purposes only. For ...

  8. Scan This Book!

    Albanese, Andrew Richard

    2007-01-01

    In this article, the author presents an interview with Brewster Kahle, leader of the Open Content Alliance (OCA). OCA book scan program is an alternative to Google's library project that aims to make books accessible online. In this interview, Kahle discusses his views on the challenges of getting books on the Web, on Google's library…

  9. Surface micromachined scanning mirrors

    Mattsson, Kent Erik

    Both aluminum cantilever and torsional scanning mirrors have been fabricated and their static and dynamic properties are studied experimentally and theoretically. The experiments showed resonance frequencies in the range of 163 k-Hz - 632 kHz for cantilever beams with Q values between 5 and 11. T...

  10. Lung gallium scan

    ... Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team. Related MedlinePlus Health Topics Lung Diseases Nuclear Scans Sarcoidosis Browse the Encyclopedia A.D.A. ...

  11. In-situ high resolution transmission electron microscopy observation of silicon nanocrystal nucleation in a SiO2 bilayered matrix

    Solid-state nucleation of Si nanocrystals in a SiO2 bilayered matrix was observed at temperatures as low as 450 °C. This was achieved by aberration corrected high-resolution transmission electron microscopy (HRTEM) with real-time in-situ heating up to 600 °C. This technique is a valuable characterization tool especially with the recent interest in Si nanostructures for light emitting devices, non-volatile memories, and third-generation photovoltaics which all typically require a heating step in their fabrication. The control of size, shape, and distribution of the Si nanocrystals are critical for these applications. This experimental study involves in-situ observation of the nucleation of Si nanocrystals in a SiO2 bilayered matrix fabricated through radio frequency co-sputtering. The results show that the shapes of Si nanocrystals in amorphous SiO2 bilayered matrices are irregular and not spherical, in contrast to many claims in the literature. Furthermore, the Si nanocrystals are well confined within their layers by the amorphous SiO2. This study demonstrates the potential of in-situ HRTEM as a tool to observe the real time nucleation of Si nanocrystals in a SiO2 bilayered matrix. Furthermore, ideas for improvements on this in-situ heating HRTEM technique are discussed

  12. The automotive transmission book

    Fischer, Robert; Jürgens, Gunter; Najork, Rolf; Pollak, Burkhard

    2015-01-01

    This book presents essential information on systems and interactions in automotive transmission technology and outlines the methodologies used to analyze and develop transmission concepts and designs. Functions of and interactions between components and subassemblies of transmissions are introduced, providing a basis for designing transmission systems and for determining their potentials and properties in vehicle-specific applications: passenger cars, trucks, buses, tractors, and motorcycles. With these fundamentals the presentation provides universal resources for both state-of-the-art and future transmission technologies, including systems for electric and hybrid electric vehicles.

  13. Kinematic analysis of conically scanned environmental properties

    Wilkerson, Thomas D. (Inventor); Sanders, Jason A. (Inventor); Andrus, Ionio Q. (Inventor)

    2003-01-01

    A method for determining the velocity of features such as wind. The method preferably includes producing sensor signals and projecting the sensor signals sequentially along lines lying on the surface of a cone. The sensor signals may be in the form of lidar, radar or sonar for example. As the sensor signals are transmitted, the signals contact objects and are backscattered. The backscattered sensor signals are received to determine the location of objects as they pass through the transmission path. The speed and direction the object is moving may be calculated using the backscattered data. The data may be plotted in a two dimensional array with a scan angle on one axis and a scan time on the other axis. The prominent curves that appear in the plot may be analyzed to determine the speed and direction the object is traveling.

  14. 67Ga lung scan

    Twenty-three patients with clinical signs of pulmonary embolic disease and lung infiltrates were studied to determine the value of gallium citrate 67Ga lung scan in differentiating embolic from inflammatory lung disease. In 11 patients without angiographically proved embolism, only seven had corresponding ventilation-perfusion defects compatible with inflammatory disease. In seven of these 11 patients, the 67Ga concentration indicated inflammatory disease. In the 12 patients with angiographically proved embolic disease, six had corresponding ventilation-perfusion defects compatible with inflammatory disease. None had an accumulation of 67Ga in the area of pulmonary infiltrate. Thus, ventilation-perfusion lung scans are of limited value when lung infiltrates are present. In contrast, the accumulation of 67Ga in the lung indicates an inflammatory process. Gallium imaging can help select those patients with lung infiltrates who need angiography

  15. Adrenal scanning in children

    Adrenal scanning with 131I-Adosterol is very useful and rather non-invasive than adrenal angiography in children. It is possible to diagnose various diseases of the adrenal glands not only structural but also functional abnormalities. In patients with adrenogenital syndromes, we are able to demonstrate hyperplasia of the adrenal glands, and in patients with aldosteronism or Cushing's syndrome differential diagnosis between bilateral hyperplasia and functional adenoma of the adrenal gland can be made. (author)

  16. Energy Scan program

    Poniatowska Katarzyna M.

    2014-04-01

    Full Text Available Femtoscopy of two non-identical particles in heavy ion collisions enables one to study the space-time asymmetry in the particle's emission process. Theoretical studies based on EPOS model performed for collision energies from the Beam Energy Scan program in STAR allow us to investigate the dependence of source sizes and dynamics effects. Obtained information will enable us to predict the collective behaviour of femtoscopic particle's source.

  17. Forensic Scanning Electron Microscope

    Keeley, R. H.

    1983-03-01

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

  18. Isotope analysis in the transmission electron microscope

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

    2016-01-01

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

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

    Suhyun Kim

    2014-10-01

    Full Text Available Scanning moiré fringe (SMF imaging by high-angle annular dark field scanning transmission electron microscopy was used to measure the strain field in the channel of a transistor with a CoSi2 source and drain. Nanometer-scale SMFs were formed with a scanning grating size of ds at integer multiples of the Si crystal lattice spacing dl (ds ∼ ndl, n = 2, 3, 4, 5. The moiré fringe formula was modified to establish a method for quantifying strain measurement. We showed that strain fields in a transistor measured by SMF images were reproducible with an accuracy of 0.02%.

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

    Scanning moiré fringe (SMF) imaging by high-angle annular dark field scanning transmission electron microscopy was used to measure the strain field in the channel of a transistor with a CoSi2 source and drain. Nanometer-scale SMFs were formed with a scanning grating size of ds at integer multiples of the Si crystal lattice spacing dl (ds ∼ ndl, n = 2, 3, 4, 5). The moiré fringe formula was modified to establish a method for quantifying strain measurement. We showed that strain fields in a transistor measured by SMF images were reproducible with an accuracy of 0.02%

  1. Terahertz Transmission Imaging with 2.52 THz Continuous Wave

    Xiao-Tong Guan; De-Wei Zheng; Min Hu; Wen-Jie Fu; Yu-Meng Cui; Xiang Fan; Liang Zhang; Ye Yuan; Jing-Yuan Xu; Yuan Li

    2013-01-01

    In this article, two terahertz transmission imaging systems are built with a 2.52 THz continuous wave laser and two types of sensors. One is array scanning system using a 124×124 pyro-electric array camera as the detector; the other is a point-wise scanning system utilizing a Golay cell as the detector. The imaging speed and quality is briefly analyzed. Terahertz (THz) imaging results demonstrate that the array scanning system has higher imaging speed with lower resolution. The point-wise scanning system has higher imaging quality with lower speed.

  2. Hydrostatic transmission design

    Dalda Rivas, Ignacio

    2009-01-01

    This project treats the analysis of the hydrostatic transmission dynamic properties using a simulation model, which has been done with the simulation program AMESim. That simulation has been the main work in the project, especially because it is a good way to understand how a hydrostatic transmission works. The hydrostatic transmission are used in heavy vehicles such as earth moving machines, agriculture machines, forest machines, industrial and mining lifters. Nowadays, the demand of that...

  3. Series Transmission Line Transformer

    Buckles, Robert A.; Booth, Rex; Yen, Boris T.

    2004-06-29

    A series transmission line transformer is set forth which includes two or more of impedance matched sets of at least two transmissions lines such as shielded cables, connected in parallel at one end ans series at the other in a cascading fashion. The cables are wound about a magnetic core. The series transmission line transformer (STLT) which can provide for higher impedance ratios and bandwidths, which is scalable, and which is of simpler design and construction.

  4. The monetary transmission mechanism

    Ireland, Peter N.

    2006-01-01

    The monetary transmission mechanism describes how policy-induced changes in the nominal money stock or the short-term nominal interest rate impact on real variables such as aggregate output and employment. Specific channels of monetary transmission operate through the effects that monetary policy has on interest rates, exchange rates, equity and real estate prices, bank lending, and firm balance sheets. Recent research on the transmission mechanism seeks to understand how these channels work ...

  5. Visualization in Scanning

    Scanning is essentially a method of making the unknown known, and for the vast majority of scanning work this means making the invisible visible. Visualization is developed as a process involving a model of eye and brain function, display performance and counter performance combined with the spatial frequency components in the object scanned. The performance of a scanner or gamma camera depends in part on its display system and experiments have been performed to determine the fractional change in count-rate which can be perceived by the eye from colour, photoscan and cathode-ray tube displays, for both circular and line sources of radioactivity. For circular sources, colour and photoscan displays are capable of making 10% increases in count-rate perceptible in backgrounds ranging from 5 to 100 counts/s for sources of 1 to 4 cm diameter, whilst cathode-ray tube and black-mark displays show only 20% at best. The results for line sources are also given. In testing for the statistical significance of count-rate differences on a scan, the counts are usually compared for equal areas. On this basis the cathode-ray tube display is only able to show five standard deviations of difference whereas colour and photoscan displays show from 2.5 to 3 standard deviations, levels not usually accepted statistically as significant. It is suggested that if the eye examines the areas surrounding the area of interest then the significance of a count-rate difference may be established more accurately and in general will be increased, thereby accounting for the visualization of apparently 'insignificant' regions. This theory is used to predict the areas of count density which should be visually perceived in the presence of noise, and extended to consider practical display conditions, which have been described in this paper. The performance of a scanner can be considered in terms of its modulation transfer function (derived from a line spread function). Fourier analysis has been performed

  6. Spinal CT scan, 1

    Methods of CT of the cervical and thoracic spines were explained, and normal CT pictures of them were described. Spinal CT was evaluated in comparison with other methods in various spinal diseases. Plain CT revealed stenosis due to spondylosis or ossification of posterior longitudinal ligament and hernia of intervertebral disc. CT took an important role in the diagnosis of spinal cord tumors with calcification and destruction of the bone. CT scan in combination with other methods was also useful for the diagnosis of spinal injuries, congenital anomalies and infections. (Ueda, J.)

  7. Spatio-temporal imaging of voltage pulses with an ultrafast scanning tunneling microscope

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

    1997-01-01

    Measurements on an ultrafast scanning tunneling microscope with simultaneous spatial and temporal resolution are presented. We show images of picosecond pulses propagating on a coplanar waveguide and resolve their mode structures. The influence of transmission line discontinuities on the mode...

  8. Poverty and price transmission

    Elleby, Christian

    A key parameter determining the welfare impact from a world market shock is the transmission elasticity which measures the average domestic response to an international price change. Many studies have estimated price transmission elasticities for a large number of countries but the variation in t...

  9. Data Transmission Concepts.

    Christenson, Chris

    1995-01-01

    Introduces some basic concepts related to the transmission of data from a computer to its peripherals to help distance educators make decisions regarding computer equipment purchases for their institutions. The following data transmission concepts are described: cables, serial and parallel, synchronous and asynchronous, bandwidth, and analog and…

  10. Nuclear Medicine Scans for Cancer

    ... My ACS » Your Local Offices Close + - Text Size Nuclear Medicine Scans for Cancer Other names for these ... inflammation, or cancer. Use of monoclonal antibodies in nuclear scans A special type of antibody made in ...

  11. Nonlinear magnetoinductive transmission lines

    Lazarides, Nikos; Tsironis, G P

    2011-01-01

    Power transmission in one-dimensional nonlinear magnetic metamaterials driven at one end is investigated numerically and analytically in a wide frequency range. The nonlinear magnetic metamaterials are composed of varactor-loaded split-ring resonators which are coupled magnetically through their mutual inductances, forming thus a magnetoiductive transmission line. In the linear limit, significant power transmission along the array only appears for frequencies inside the linear magnetoinductive wave band. We present analytical, closed form solutions for the magnetoinductive waves transmitting the power in this regime, and their discrete frequency dispersion. When nonlinearity is important, more frequency bands with significant power transmission along the array may appear. In the equivalent circuit picture, the nonlinear magnetoiductive transmission line driven at one end by a relatively weak electromotive force, can be modeled by coupled resistive-inductive-capacitive (RLC) circuits with voltage-dependent cap...

  12. Scanned-cantilever atomic force microscope with large scanning range

    Jintao Yang; Wendong Xu

    2006-01-01

    A scanned-cantilever atomic force microscope (AFM) with large scanning range is proposed, which adopts a new design named laser spot tracking. The scanned-cantilever AFM uses the separate flexure x-y scanner and z scanner instead of the conventional piezoelectric tube scanner. The closed-loop control and integrated capacitive sensors of these scanners can insure that the images of samples have excellent linearity and stability. According to the experimental results, the scanned-cantilever AFM can realize maximal 100 × 100 (μm) scanning range, and 1-nm resolution in z direction, which can meet the requirements of large scale sample testing.

  13. In-situ transmission electron microscopy and first-principles study of Au (100) surface dislocation dynamics

    Song, B.; Jansen, J.; Tichelaar, F. D.; Zandbergen, H. W.; Gajewski, G.; Pao, C. W.; Srolovitz, D. J.

    2013-02-01

    In-situ aberration-corrected transmission electron microscopy combined with density functional theory (DFT) calculations are employed to elucidate the electron beam induced dynamics of surface dislocations on ~ 4 nm × 6 nm sized Au (100) terraces located on top of hillock shaped Au at room temperature and 77 K at video rate (20 frames/s). At room temperature, very small terraces (< 4 × 5 atoms) sink into the lower terrace forming surface dislocations associated with a (5 × 1) surface reconstruction unit cell. This injection occurs provided that the number of atoms of the terrace fits the number of extra atoms required to form the surface dislocation. The surface dislocation consists of either 5 or 3 (Type I and Type II) hexagonally stacked atom rows. While the surface dislocations tend to reside near terrace edges, in ~ 20% of the video frames, the surface dislocation resides near the center of the terrace. The occurrence of Type I or Type II structures depends on the terrace width. DFT calculations show that Type I surface dislocations are more stable than Type II, for dislocations that do not span the entire terrace width, in agreement with observations. Surface dislocations are observed to flip by 90° during the experimental observations; the pathway and energy barrier (1.01 eV) for such flips is clarified through DFT calculations. At 77 K, no injections are observed, but surface dislocations do rarely form from an unreconstructed surface. In addition to dislocation flipping, multiple, dynamic dislocation configurations were observed in conjunction with terrace growth along the dislocation direction.

  14. Quadrature wavelength scanning interferometry.

    Moschetti, Giuseppe; Forbes, Alistair; Leach, Richard K; Jiang, Xiang; O'Connor, Daniel

    2016-07-10

    A novel method to double the measurement range of wavelength scanning interferometery (WSI) is described. In WSI the measured optical path difference (OPD) is affected by a sign ambiguity, that is, from an interference signal it is not possible to distinguish whether the OPD is positive or negative. The sign ambiguity can be resolved by measuring an interference signal in quadrature. A method to obtain a quadrature interference signal for WSI is described, and a theoretical analysis of the advantages is reported. Simulations of the advantages of the technique and of signal errors due to nonideal quadrature are discussed. The analysis and simulation are supported by experimental measurements to show the improved performances. PMID:27409307

  15. The normal bone scan

    This paper discusses applications of the bone scan. It is the most frequently performed nuclear medicine investigation, the commonest indication being the detection of occult metastases, for which purpose the entire skeleton should be imaged. For other purposes it is often adequate to examine only part of the skeleton. The amount of isotope taken up at any site depends primarily on the local rate of bone turnover rather than on bone mass. The scintigraphic appearance therefore does not necessarily correlate with the radiographic one; however, as there is a relationship between the rate at which bone is replaced and the quantity of bone which is present at any point, the two appearances are not entirely unrelated. Recognition of abnormality is based on a detailed knowledge of normal scintigraphic appearances

  16. Telescopic horizon scanning.

    Koenderink, Jan

    2014-12-20

    The problem of "distortionless" viewing with terrestrial telescopic systems (mainly "binoculars") remains problematic. The so called "globe effect" is only partially counteracted in modern designs. Theories addressing the phenomenon have never reached definitive closure. In this paper, we show that exact distortionless viewing with terrestrial telescopic systems is not possible in general, but that it is in principle possible in-very frequent in battle field and marine applications-the case of horizon scanning. However, this involves cylindrical optical elements. For opto-electronic systems, a full solution is more readily feasible. The solution involves a novel interpretation of the relevant constraints and objectives. For final design decisions, it is not necessary to rely on a corpus of psychophysical (or ergonomic) data, although one has to decide whether the instrument is intended as an extension of the eye or as a "pictorial" device. PMID:25608206

  17. A Scanning Cavity Microscope

    Mader, Matthias; Hänsch, Theodor W; Hunger, David

    2014-01-01

    Imaging of the optical properties of individual nanosystems beyond fluorescence can provide a wealth of information. However, the minute signals for absorption and dispersion are challenging to observe, and only specialized techniques requiring sophisticated noise rejection are available. Here we use signal enhancement in a scanning optical microcavity to demonstrate ultra-sensitive imaging. Harnessing multiple interactions of probe light with a sample within an optical resonator, we achieve a 1700-fold signal enhancement compared to diffraction-limited microscopy. We demonstrate quantitative imaging of the extinction cross section of gold nanoparticles with a sensitivity below 1 nm2, we show a method to improve spatial resolution potentially below the diffraction limit by using higher order cavity modes, and we present measurements of the birefringence and extinction contrast of gold nanorods. The demonstrated simultaneous enhancement of absorptive and dispersive signals promises intriguing potential for opt...

  18. Micro scanning probes

    Niblock, T

    2001-01-01

    This thesis covers the design methodology, theory, modelling, fabrication and evaluation of a Micro-Scanning-Probe. The device is a thermally actuated bimorph quadrapod fabricated using Micro Electro Mechanical Systems technology. A quadrapod is a structure with four arms, in this case a planar structure with the four arms forming a cross which is dry etched out of a silicon diaphragm. Each arm has a layer of aluminium deposited on it forming a bimorph. Through heating each arm actuation is achieved in the plane of the quadrapod and the direction normal to it. Fabrication of the device has required the development of bulk micromachining techniques to handle post CMOS fabricated wafers and the patterning of thickly sputtered aluminium in bulk micro machined cavities. CMOS fabrication techniques were used to incorporate diodes onto the quadrapod arms for temperature measurement of the arms. Fine tungsten and silicon tips have also been fabricated to allow tunnelling between the tip and the platform at the centr...

  19. CT scans in encephalitis

    Generally, CT scans reveal a decrease in the volume of the ventricular system, sylvian fissures and cortical sulci in the acute stage of encephalitis, and softening of the cerebral lobes with dilatation of the lateral ventricles and subarachnoidian dilated spaces in the chronic stage. We encountered three cases of encephalitis: mumps (case 1), herpes simplex (case 2), and syphilis (case 3). In case 1, brain edema was seen in the acute stage and brain atrophy in the chronic stage. In case 2, necrosis of the temporal pole, which is pathognomonic in herpes simplex encephalitis, was recognized. And in case 3, multiple lesions whose CT appearance was enhanced by contrast materials were found scattered over the whole brain. These lesions were diagnosed as inflammatory granuloma by histological examination. (author)

  20. A mini-rapid-scan-spectrophotometer.

    Schmidt, Werner

    2004-02-27

    The mini-rapid-scan-spectrophotometer (Mini-RSS) is a scanning single-beam spectrophotometer that has been patented. It is based on a minimum of reflections and involves exclusively mirrors as beam-deflecting components. This way stray light is minimized, which results in an excellent light-throughput, high dynamics, low cost, compactness and rigidity. The Mini-RSS has been designed as a multi-purpose instrument that allows absorption, transmission, reflection, fluorescence and luminescence measurements in a single-beam mode. Its spectral range extends from the UV and visible spectrum to the IR. This provides for the possibility to measure even optically unfavorable, highly turbid or scattering samples that would be otherwise inaccessible to investigations with commercial spectrophotometers. A miniaturized and very sensitive photomultiplier-module (PM) of high dynamics allows in the visible spectral range absorbance measurements that cover up to four OD units. The Mini-RSS is capable of scanning up to 100 spectra per second with a resolution of 12 bit and 500 points. The linear dispersion is currently 5 nm and the stray light level <0.01%. PMID:14980786

  1. Wireless Power Transmission

    Pragati S. Chawardol

    2014-12-01

    Full Text Available A great concern has been voiced in recent years over the extensive use of energy, the limited supply of resourses, and the pollution of the environment from the use of present energy conversion systems. Electrical power accounts for much of the energy consumed. One of the major issue in power system is the losses occurs during the transmission and distribution of electrical power. As the demand increases day by day, the power generation increases and the power loss is also increased. The major amount of power loss occurs during transmission and distribution. The resistance of the wire used in the electrical grid distribution system causes a loss of 26-30% of the energy generated. This loss implies that our present system of electrical distribution is only 70-74% efficient. The above discussed problem can be solved by choose an alternative option for power transmission which could provide much higher efficiency, low transmission cost and avoid power theft. Wireless power transmission is one of the promising technologies and may be the righteous alternative for efficient power transmission. This paper focuses on the past and future possible advancements in WPT. Also the proposed method and technologies in WPT that will make the loss of energy during transmission and distribution to minimum are discussed. Keyword

  2. Understanding Ebola Virus Transmission

    Seth Judson

    2015-02-01

    Full Text Available An unprecedented number of Ebola virus infections among healthcare workers and patients have raised questions about our understanding of Ebola virus transmission. Here, we explore different routes of Ebola virus transmission between people, summarizing the known epidemiological and experimental data. From this data, we expose important gaps in Ebola virus research pertinent to outbreak situations. We further propose experiments and methods of data collection that will enable scientists to fill these voids in our knowledge about the transmission of Ebola virus.

  3. SCAN: a Fortran syntax analyzer

    SCAN is a computer program which analyzes the syntax of a Fortran program. It reads statements of a Fortran program, checks the grammatical validity of them, and produces tables of the analyzed results and intermediate codes for further use. SCAN recognizes the Fortran syntax of the Japan Industrial Standards-7000, plus some Fortran-H statements. In this report, the structure of SCAN, the methods used by the SCAN to analyze statements, tables and intermediate Buckus form texts produced by the SCAN, are presented. The SCAN itself is also written in Fortran language and consists of about 5000 statements. By slight modifications the SCAN may be useful for any application which needs analysis operations of Fortran syntax. (author)

  4. Tractor Transmissions. A Teaching Reference.

    American Association for Agricultural Engineering and Vocational Agriculture, Athens, GA.

    The manual was developed as a reference for teaching students about transmissions in farm tractors. The manual is divided into five sections: (1) transmission history, (2) gears and bearings in transmission, (3) sliding-gear transmissions, (4) planetary gearing, and (5) glossary. The working principles of the sliding-gear transmission, the most…

  5. Transmissions in vehicles 2010

    NONE

    2010-07-01

    Within the international VDI congress 'Gears in vehicles 2010' of the VDI Wissensforum GmbH (Duesseldorf, Federal Republic of Germany) between 22nd and 23rd June, 2010, in Friedrichshafen (Federal Republic of Germany), the following lectures were held: (1) 8HP70H - The moldhybrid transmission from ZF - Cjallenges and achievements (P. Gutmann); (2) GETRAG boosted range extender - A highly flexible electric powertrain for maximum CO{sub 2} reduction (S. Huepkes); (3) E-Transmission between full-hybrid and E-drive (P. Tenberge); (4) Reducing NO{sub x} and particulate emissions in electrified drivelines (R. Kuberczyk); (5) Simulation aided HEV and EV development: from the component to the whole powertrain (A. Gacometti); (6) Investigations on operating behaviour of the optimized CVT hybrid driveline (B.-R. Hoehn); (7) Customer-oriented dimensioning of electrified drivetrains (M. Eghtessad); (8) Decentralized optimal control strategy for parallel hybrid electric vehicles (A. Frenkel); (9) The new generation 6-speed automatic transmission AF40 (G. Bednarek); (10) Customized mechatronic solutions for integrated transmission control units (M. Wieczorek); (11) The optimal automatic transmission for front-transverse applications - Planetary transmissions or dual clutch transmissions? (G. Gumpoltsberger); (12) The new shift-by-wire gearshift lever for the Audi A8 - Requirements and concept (T. Guttenbergere); (13) The new shift-by-wire gearshift lever for the Audi A8 - Realization (A. Giefer); (14) Fuel-efficient transmissions of the future: Calculation of the efficiency factor for vehicle transmissions (B. Volpert); (15) HT-ACM: A new polymer generation for static and dynamic gearbox sealing solutions (E. Osen); (16) 'Energy efficiency equipped solutions by SKF' for power train applications - A contribution to CO{sub 2} - emission reduction and sustainability (T. Bobke); (17) 6-Ratio planetary shift transmission controlled by 4 external brakes, and design

  6. Kansas Electric Transmission Lines

    Kansas Data Access and Support Center — This data set is a digital representation of the EletcircTransmission lines for the State of Kansas as maintained by the Kansas Corporation Commission. Data is...

  7. Transmission of Flu (Influenza)

    ... Skip Content Marketing Share this: Main Content Area Flu (Influenza) Transmission How Flu Spreads Coughing and Sneezing People with flu can ... not be shared without washing thoroughly first. The Flu Is Contagious You may be able to pass ...

  8. Down hole transmission system

    Hall, David R.; Hall, Jr., H. Tracy

    2007-07-24

    A transmission system in a downhole component comprises a data transmission element in both ends of the downhole component. Each data transmission element houses an electrically conducting coil in a MCEI circular trough. The electrically conducting coil comprises at least two generally fractional loops. In the preferred embodiment, the transmission elements are connected by an electrical conductor. Preferably, the electrical conductor is a coaxial cable. Preferably, the MCEI trough comprises ferrite. In the preferred embodiment, the fractional loops are connected by a connecting cable. In one aspect of the present invention, the connecting cable is a pair of twisted wires. In one embodiment the connecting cable is a shielded pair of twisted wires. In another aspect of the present invention, the connecting cable is a coaxial cable. The connecting cable may be disposed outside of the MCEI circular trough.

  9. Gravity wave transmission diagram

    Tomikawa, Y.

    2015-01-01

    A new method of obtaining power spectral distribution of gravity waves as a function of ground-based horizontal phase speed and propagation direction from airglow observations has recently been proposed. To explain gravity wave power spectrum anisotropy, a new gravity wave transmission diagram was developed in this study. Gravity wave transmissivity depends on the existence of critical and turning levels for waves that are determined by background horizontal wind distributio...

  10. Understanding Ebola Virus Transmission

    Seth Judson; Joseph Prescott; Vincent Munster

    2015-01-01

    An unprecedented number of Ebola virus infections among healthcare workers and patients have raised questions about our understanding of Ebola virus transmission. Here, we explore different routes of Ebola virus transmission between people, summarizing the known epidemiological and experimental data. From this data, we expose important gaps in Ebola virus research pertinent to outbreak situations. We further propose experiments and methods of data collection that will enable scientists to fil...

  11. Eliminating Perinatal HIV Transmission

    2012-11-26

    In this podcast, CDC’s Dr. Steve Nesheim discusses perinatal HIV transmission, including the importance of preventing HIV among women, preconception care, and timely HIV testing of the mother. Dr. Nesheim also introduces the revised curriculum Eliminating Perinatal HIV Transmission intended for faculty of OB/GYN and pediatric residents and nurse midwifery students.  Created: 11/26/2012 by Division of HIV/AIDS Prevention.   Date Released: 11/26/2012.

  12. Glutamate Transmission in Addiction

    Kalivas, Peter W.; LaLumiere, Ryan; Knackstedt, Lori; Shen, Haowei

    2008-01-01

    Cortico-striatal glutamate transmission has been implicated in both the initiation and expression of addiction related behaviors, such as locomotor sensitization and drug seeking. While glutamate transmission onto dopamine cells in the ventral tegmental area undergoes transient plasticity important for establishing addiction-related behaviors, glutamatergic plasticity in the nucleus accumbens is critical for the expression of these behaviors. This information points to the value of exploring ...

  13. Continuously Variable Transmission

    Grana, D. C.

    1985-01-01

    Chain slides along two cones, in novel transmission concept. Transmission includes chain drive between two splined shafts. Chain sprockets follow surfaces of two cones. As one chain sprocket moves toward smaller diameter other chain sprocket moves toward larger diameter, thereby changing "gear" ratio. Movement initiated by tension applied to chain by planetary gear mechanism. Device positive, simple, and efficient over wide range of speed ratios.

  14. Gravity wave transmission diagram

    Tomikawa, Yoshihiro

    2016-07-01

    A possibility of gravity wave propagation from a source region to the airglow layer around the mesopause has been discussed based on the gravity wave blocking diagram taking into account the critical level filtering alone. This paper proposes a new gravity wave transmission diagram in which both the critical level filtering and turning level reflection of gravity waves are considered. It shows a significantly different distribution of gravity wave transmissivity from the blocking diagram.

  15. Radionuclide brain scanning

    At one stage of medical imaging development, radionuclide brain scanning was the only technique available for imaging of the brain. Advent of CT and MRI pushed it to the background. It regained some of the grounds lost to ''allied advances'' with the introduction of brain perfusion radiopharmaceuticals. Positron emission tomography is a promising functional imaging modality that at present will remain as a research tool in special centres in developed countries. However, clinically useful developments will gradually percolate from PET to SPECT. The non-nuclear imaging methods are totally instrument dependent; they are somewhat like escalators, which can go that far and no further. Nuclear imaging has an unlimited scope for advance because of the new developments in radiopharmaceuticals. As the introduction of a radiopharmaceutical is less costly than buying new instruments, the recent advances in nuclear imaging are gradually perfusing through the developing countries also. Therefore, it is essential to follow very closely PET developments because what is research today might become routine tomorrow

  16. Scanning probe nanoimprint lithography

    Dinelli, F; Baschieri, P [IPCF, Consiglio Nazionale delle Ricerche, CNR Campus, Via G. Moruzzi 1, Pisa PI 56100 (Italy); Menozzi, C; Facci, P [CNR-INFM S3 National Research Center on Nanostructure and BioSystems at Surfaces, Via Campi 213/a, 41100 Modena (Italy); Pingue, P, E-mail: pingue@sns.it [NEST, Scuola Normale Superiore and CNR-INFM, Piazza San Silvestro 12, I-56127 Pisa (Italy)

    2010-02-19

    The present paper reports on a novel lithographic approach at the nanoscale level, which is based on scanning probe microscopy (SPM) and nanoimprint lithography (NIL). The experimental set-up consists of an atomic force microscope (AFM) operated via software specifically developed for the purpose. In particular, this software allows one to apply a predefined external load for a given lapse of time while monitoring in real-time the relative distance between the tip and the sample as well as the normal and lateral force during the embossing process. Additionally, we have employed AFM tips sculptured by means of focused ion beam in order to create indenting tools of the desired shape. Anti-sticking layers can also be used to functionalize the tips if one needs to investigate the effects of different treatments on the indentation and de-molding processes. The lithographic capabilities of this set-up are demonstrated on a polystyrene NIL-patterned sample, where imprinted features have been obtained upon using different normal load values for increasing time intervals, and on a thermoplastic polymer film, where the imprint process has been monitored in real-time.

  17. Scanning probe nanoimprint lithography

    Dinelli, F.; Menozzi, C.; Baschieri, P.; Facci, P.; Pingue, P.

    2010-02-01

    The present paper reports on a novel lithographic approach at the nanoscale level, which is based on scanning probe microscopy (SPM) and nanoimprint lithography (NIL). The experimental set-up consists of an atomic force microscope (AFM) operated via software specifically developed for the purpose. In particular, this software allows one to apply a predefined external load for a given lapse of time while monitoring in real-time the relative distance between the tip and the sample as well as the normal and lateral force during the embossing process. Additionally, we have employed AFM tips sculptured by means of focused ion beam in order to create indenting tools of the desired shape. Anti-sticking layers can also be used to functionalize the tips if one needs to investigate the effects of different treatments on the indentation and de-molding processes. The lithographic capabilities of this set-up are demonstrated on a polystyrene NIL-patterned sample, where imprinted features have been obtained upon using different normal load values for increasing time intervals, and on a thermoplastic polymer film, where the imprint process has been monitored in real-time.

  18. Gastrointestinal scanning agent

    An easily prepared radiolabeled gastrointestinal scanning agent is described. Technetium-99m has ideal characteristics for imaging the upper and lower GI tract and determining stomach emptying and intestinal transit time when used with an insoluble particulate material. For example, crystalline and amorphous calcium phosphate particles can be effectively labeled in a one-step process using sup(99m)TcO4 and SnCl2. These labeled particles have insignificant mass and when administered orally pass through the GI tract unchanged, without affecting the handling and density of the intestinal contents. Visualization of the esophageal entry into the stomach, the greater and lesser curvatures of the stomach, ejection into the duodenum, and rates of passage through the upper and lower GI tract are obtained. The slurry of sup(99m)TC particulate can be given rectally by enema. Good images of the cecum and the ascending, transverse, and descending colon are obtained. Mucosal folds and the splenic and hepatic flexures are visualized. The resilience of the large intestine is also readily visualized by pneumocolonographic techniques. (author)

  19. National transmission grid study

    Abraham, Spencer [USDOE Office of the Secretary of Energy, Washington, DC (United States)

    2003-05-31

    The National Energy Policy Plan directed the U.S. Department of Energy (DOE) to conduct a study to examine the benefits of establishing a national electricity transmission grid and to identify transmission bottlenecks and measures to address them. DOE began by conducting an independent analysis of U.S. electricity markets and identifying transmission system bottlenecks using DOE’s Policy Office Electricity Modeling System (POEMS). DOE’s analysis, presented in Section 2, confirms the central role of the nation’s transmission system in lowering costs to consumers through increased trade. More importantly, DOE’s analysis also confirms the results of previous studies, which show that transmission bottlenecks and related transmission system market practices are adding hundreds of millions of dollars to consumers’ electricity bills each year. A more detailed technical overview of the use of POEMS is provided in Appendix A. DOE led an extensive, open, public input process and heard a wide range of comments and recommendations that have all been considered.1 More than 150 participants registered for three public workshops held in Detroit, MI (September 24, 2001); Atlanta, GA (September 26, 2001); and Phoenix, AZ (September 28, 2001).

  20. Noise Equivalent Counts Based Emission Image Reconstruction Algorithm of Tomographic Gamma Scanning

    Wang, Ke; Feng, Wei; Han, Dong

    2014-01-01

    Tomographic Gamma Scanning (TGS) is a technique used to assay the nuclide distribution and radioactivity in nuclear waste drums. Both transmission and emission scans are performed in TGS and the transmission image is used for the attenuation correction in emission reconstructions. The error of the transmission image, which is not considered by the existing reconstruction algorithms, negatively affects the final results. An emission reconstruction method based on Noise Equivalent Counts (NEC) is presented. Noises from the attenuation image are concentrated to the projection data to apply the NEC Maximum-Likelihood Expectation-Maximization algorithm. Experiments are performed to verify the effectiveness of the proposed method.

  1. Wireless data signal transmission system

    2014-01-01

    The present invention relates to a method for providing a radio frequency signal for transmission, a system for providing a radio frequency signal for transmission and a method for wireless data transmission between a transmitter and a receiver.......The present invention relates to a method for providing a radio frequency signal for transmission, a system for providing a radio frequency signal for transmission and a method for wireless data transmission between a transmitter and a receiver....

  2. TOPICAL REVIEW: Present status and future prospects of spherical aberration corrected TEM/STEM for study of nanomaterials

    Nobuo Tanaka

    2008-01-01

    Full Text Available The present status of Cs-corrected TEM/STEM is described from the viewpoint of the observation of nanomaterials. Characteristic features in TEM and STEM are explained using the experimental data obtained by our group and other research groups. Cs correction up to the 3rd-order aberration of an objective lens has already been established and research interest is focused on correcting the 5th-order spherical aberration and the chromatic aberration in combination with the development of a monochromator below an electron gun for smaller point-to-point resolution in optics. Another fundamental area of interest is the limitation of TEM and STEM resolution from the viewpoint of the scattering of electrons in crystals. The minimum size of the exit-wave function below samples undergoing TEM imaging is determined from the calculation of scattering around related atomic columns in the crystals. STEM does not have this limitation because the resolution is, in principle, determined by the probe size. One of the future prospects of Cs-corrected TEM/STEM is the possibility of extending the space around the sample holder by correcting the chromatic and spherical aberrations. This wider space will contribute to the ease of performing in situ experiments and various combinations of TEM and other analysis methods. High-resolution, in situ dynamic and 3D observations/analysis are the most important keywords in the next decade of high-resolution electron microscopy.

  3. Aberration correction in double-pass amplifiers through the use of phase-conjugate mirrors and/or adaptive optics

    Jackel, Steven M.; Moshe, Inon; Lavi, Raphael

    2001-04-01

    Corrrection of birefringence induced effects (depolarization and bipolar focusing) was achieved in double-pass amplifiers using a Faraday rotator placed between the laser rod and the retroreflecting optic. A necessary condition was that each ray in the beam retraced its path through the amplifying medium. Retrace was limited by imperfect conjugate-beam fidelity and by nonreciprocal double-pass indices of refraction. We compare various retroreflectors: stimulated Brillouin scatter phase-conjugate-mirrors (PCMs), PCMs with relay lenses to image the rod principal plane onto the PCM entrance aperture (IPCMs), IPCMs with external, adaptively-adjusted, astigmatism-correcting cylindrical doublets, and all adaptive optics imaging variable-radius-mirrors (IVRMs). Results with flashlamp pumped, Nd:Cr:GSGG double-pass amplifiers show that average output power increased fivefold with a Faraday rotator plus complete nonlinear optics retroreflector package (IPCM+cylindrical zoom), and that this represents an 80% increase over the power achieved using just a PCM. Far better results are, however, achieved with an IVRM.

  4. Atomic-resolution studies of In2O3-ZnO compounds on aberration-corrected electron microscopes

    In this work, the characteristic inversion domain microstructures of In2O3(ZnO)m (m=30) compounds were investigated by TEM methods. At bright-atom contrast condition, atomically resolved HR-TEM images of In2O3(ZnO)30 were successfully acquired in [1 anti 100] zone axis of ZnO, with projected metal columns of ∝1.6 A well resolved. From contrast maxima in the TEM images, local lattice distortions at the pyramidal inversion domain boundaries were observed for the first time. Lattice displacements and the strain field in two-dimensions were visualized and measured using the 'DALI' algorithm. Atomically resolved single shot and focal series images of In2O3(ZnO)30 were achieved in both zone axes of ZnO, [1 anti 100] and [2 anti 1 anti 10], respectively. The electron waves at the exit-plane were successfully reconstructed using the software package 'TrueImage'. Finally, a three dimensional atomic structure model for the pyramidal IDB was proposed, with an In distribution of 10%, 20%, 40%, 20% and 10% of In contents over 5 atom columns along basal planes, respectively. Through a detailed structural study of In2O3(ZnO)m compounds by using phase-contrast and Z-contrast imaging at atomic resolution, In3+ atoms are determined with trigonal bi-pyramidal co-ordination and are distributed at the pyramidal IDBs. (orig.)

  5. AO-OCT for in vivo mouse retinal imaging: Application of adaptive lens in wavefornt sensorless aberration correction

    Bonora, Stefano; Jian, Yifan; Pugh, Edward N.; Sarunic, Marinko V.; Zawadzki, Robert J.

    2014-03-01

    We demonstrate Adaptive optics - Optical Coherence Tomography (OCT) with modal sensorless Adaptive Optics correction with the use of novel Adaptive Lens (AL) applied for in-vivo imaging of mouse retinas. The AL can generate low order aberrations: defocus, astigmatism, coma and spherical aberration that were used in an adaptive search algorithm. Accelerated processing of the OCT data with a Graphic Processing Unit (GPU) permitted real time extraction of image projection total intensity for arbitrarily selected retinal depth plane to be optimized. Wavefront sensorless control is a viable option for imaging biological structures for which AOOCT cannot establish a reliable wavefront that could be corrected by wavefront corrector. Image quality improvements offered by adaptive lens with sensorless AO-OCT was evaluated on in vitro samples followed by mouse retina data acquired in vivo.

  6. Tomographic scanning apparatus

    Scanning apparatus is disclosed for use in computerized axial tomography systems. The apparatus includes an assembly rotatable about an axis extending along a central opening defined therein, and means for positioning the body portion to be examined within the central opening so that the axis of assembly rotation is perpendicular to a plane passing through the bodily structures to be examined. A source of penetrating radiation is mounted on the assembly toward one side thereof and provides radiation in the form of a fan beam. Detector means for the radiation are positioned on the assembly opposite the source, enabling detection of radiation which traverses laterally and is not absorbed in the thin body section in which the aforementioned plane resides. Means are provided for rotating the assembly so that the fan beam impinges upon said body portion at a plurality of incident directions. Signal processing and conditioning means mounted on the assembly and movable therewith, receive the output signals from the detector means and amplify and convert same to digital form. Slip ring interconnection means rotatable with the assembly, receive the outputs from the signal processors and conditioners and interfeed these signals to a computerized image reconstruction station. Slip rings rotatable with the assembly also provide interconnection enabling power and control inputs to the radiation source and to other portions of the apparatus. The assembly is continuously rotatable through successive 360 degree rotations and the examination sequence may be initiated at any point in the rotation of the assembly. The detector comprises an array of elements and means are provided for adjusting the gains of each channel associated with the individual detector elements as an incident of the examination process, thereby enabling compensation for drift in the channels

  7. Hyperchromatic laser scanning cytometry

    Tárnok, Attila; Mittag, Anja

    2007-02-01

    In the emerging fields of high-content and high-throughput single cell analysis for Systems Biology and Cytomics multi- and polychromatic analysis of biological specimens has become increasingly important. Combining different technologies and staining methods polychromatic analysis (i.e. using 8 or more fluorescent colors at a time) can be pushed forward to measure anything stainable in a cell, an approach termed hyperchromatic cytometry. For cytometric cell analysis microscope based Slide Based Cytometry (SBC) technologies are ideal as, unlike flow cytometry, they are non-consumptive, i.e. the analyzed sample is fixed on the slide. Based on the feature of relocation identical cells can be subsequently reanalyzed. In this manner data on the single cell level after manipulation steps can be collected. In this overview various components for hyperchromatic cytometry are demonstrated for a SBC instrument, the Laser Scanning Cytometer (Compucyte Corp., Cambridge, MA): 1) polychromatic cytometry, 2) iterative restaining (using the same fluorochrome for restaining and subsequent reanalysis), 3) differential photobleaching (differentiating fluorochromes by their different photostability), 4) photoactivation (activating fluorescent nanoparticles or photocaged dyes), and 5) photodestruction (destruction of FRET dyes). With the intelligent combination of several of these techniques hyperchromatic cytometry allows to quantify and analyze virtually all components of relevance on the identical cell. The combination of high-throughput and high-content SBC analysis with high-resolution confocal imaging allows clear verification of phenotypically distinct subpopulations of cells with structural information. The information gained per specimen is only limited by the number of available antibodies and by sterical hindrance.

  8. Physical design of scanning gantry for proton therapy facility

    Jiao, Y.; Satogata, T.; Guan, X-L.; Fang, S-X.; Wie, J.; Tang, J-Y.; Chen, Y.; Qui, J.; Shu, H.

    2010-03-01

    A proton therapy facility based on a linac injector and a slow cycling synchrotron is proposed. To achieve effective treatment of cancer, a scanning gantry is required. The flexible transmission of beam and high beam position accuracy are the most basic requirements for a gantry. The designed gantry optics and scanning system are presented. Great efforts are put into studying the sensitivity of the beam position in the isocenter to the element misalignments. It shows that quadrupole shift makes the largest contribution and special attention should be paid to it.

  9. Gallium scans in myasthenia gravis

    Swick, H.M. (Univ. of Kentucky, Lexington); Preston, D.F.; McQuillen, M.P.

    1976-01-01

    A study was conducted to determine whether /sup 67/Ga scans could be used for the detection of thymomas and to investigate the activity of the thymus gland in patients with myasthenia gravis. Scans of the anterior mediastinum proved to be a reliable way to detect thymomas. The scans were positive in eight patients including three with myasthenia gravis and histologically proved thymomas, three others with severe myasthenia gravis and thymic tumors, and two with histologically proved thymomas not associated with myasthenia. Activity on /sup 67/Ga scans was not directly related to the increased activity of the thymus gland that is presumed to be associated with myasthenia gravis. (HLW)

  10. Gallium scans in myasthenia gravis

    A study was conducted to determine whether 67Ga scans could be used for the detection of thymomas and to investigate the activity of the thymus gland in patients with myasthenia gravis. Scans of the anterior mediastinum proved to be a reliable way to detect thymomas. The scans were positive in eight patients including three with myasthenia gravis and histologically proved thymomas, three others with severe myasthenia gravis and thymic tumors, and two with histologically proved thymomas not associated with myasthenia. Activity on 67Ga scans was not directly related to the increased activity of the thymus gland that is presumed to be associated with myasthenia gravis

  11. Scanning tunneling microscopy II further applications and related scanning techniques

    Güntherodt, Hans-Joachim

    1995-01-01

    Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those described in STM I, these studies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described in chapters on scanning force microscopy, magnetic force microscopy, and scanning near-field optical microscopy, together with a survey of other related techniques. Also described here is the use of a scanning proximal probe for surface modification. Together, the two volumes give a comprehensive account of experimental aspects of STM. They provide essential reading and reference material for all students and researchers involved in this field. In this second edition the text has been updated and new methods are discussed.

  12. Scanning tunneling microscopy II further applications and related scanning techniques

    Güntherodt, Hans-Joachim

    1992-01-01

    Scanning Tunneling Microscopy II, like its predecessor, presents detailed and comprehensive accounts of the basic principles and broad range of applications of STM and related scanning probe techniques. The applications discussed in this volume come predominantly from the fields of electrochemistry and biology. In contrast to those described in Vol. I, these sudies may be performed in air and in liquids. The extensions of the basic technique to map other interactions are described inchapters on scanning force microscopy, magnetic force microscopy, scanning near-field optical microscopy, together with a survey of other related techniques. Also described here is the use of a scanning proximal probe for surface modification. Togehter, the two volumes give a comprehensive account of experimental aspcets of STM. They provide essentialreading and reference material for all students and researchers involvedin this field.

  13. 2006 Final Transmission Proposal.

    United States. Bonneville Power Administration.

    2005-06-01

    This Record of Decision (ROD) contains the decisions of the Administrator of the Bonneville Power Administration BPABPA with respect to the adoption of transmission and ancillary services rates for the two-year rate period beginning October 1, 2005, and ending September 30, 2007 (fiscal years (FY) 2006-2007)(2006 Final Transmission and Ancillary Services Rate Proposal). These decisions are based on the record compiled in this rate proceeding. The transmission and ancillary services rates adopted in this ROD are the rates proposed as a result of a comprehensive settlement agreement between BPA's Transmission Business Line (BPA-TBL) and a diverse group of transmission customers, including BPA's Power Business Line (BPA-PBL), regional investor-owned utilities, partial and full requirements customers of the BPA-PBL, Direct Services Industrial (DSI) customers, and merchant generators. The decisions in this ROD to adopt the rates and charges proposed by the settlement agreement are not intended to create or imply any factual , legal, procedural or substantive precedent, or to create agreement to any underlying principle or methodology.

  14. Quantitative analysis of image contrast in phase contrast STEM for low dose imaging

    This work quantitatively evaluates the contrast in phase contrast images of thin vermiculite crystals recorded by TEM and aberration-corrected bright-field STEM. Specimen movement induced by electron irradiation remains a major problem limiting the phase contrast in TEM images of radiation-sensitive specimens. While spot scanning improves the contrast, it does not eliminate the problem. One possibility is to utilise aberration-corrected scanning transmission electron microscopy (STEM) with an Angstrom-sized probe to illuminate the sample, and thus further reduce irradiation-induced specimen movement. Vermiculite is relatively radiation insensitive in TEM to electron fluences below 100,000 e-/A2 and this is likely to be similar for STEM although different damage mechanisms could occur. We compare the performance of a TEM with a thermally assisted field emission electron gun (FEG) and charge coupled device (CCD) image capture to the performance of STEMs with spherical aberration correction, cold field emission electron sources and photomultiplier tube image capture at a range of electron fluences and similar illumination areas. We show that the absolute contrast of the phase contrast images obtained by aberration-corrected STEM is better than that obtained by TEM. Although the STEM contrast is higher, the efficiency of collection of electrons in bright field STEM is still much less than that in bright field TEM (where for thin samples virtually all the electrons contribute to the image), and the SNR of equivalent STEM images is three times lower. This is better than expected, probably due to the absence of a frequency dependent modulation transfer function in the STEM detection system. With optimisation of the STEM bright field collection angles, the efficiency may approach that of bright field TEM, and if reductions in beam-induced specimen movement are found, STEM could surpass the overall performance of TEM.

  15. Nanostructured PLD-grown gadolinia doped ceria: Chemical and structural characterization by transmission electron microscopy techniques

    Rodrigo, Katarzyna Agnieszka; Wang, Hsiang-Jen; Heiroth, Sebastian;

    2011-01-01

    The morphology as well as the spatially resolved elemental and chemical characterization of 10 mol% gadolinia doped ceria (CGO10) structures prepared by pulsed laser deposition (PLD) technique are investigated by scanning transmission electron microscopy accompanied with electron energy loss...

  16. Aerosol Transmission of Filoviruses

    Berhanu Mekibib

    2016-05-01

    Full Text Available Filoviruses have become a worldwide public health concern because of their potential for introductions into non-endemic countries through international travel and the international transport of infected animals or animal products. Since it was first identified in 1976, in the Democratic Republic of Congo (formerly Zaire and Sudan, the 2013–2015 western African Ebola virus disease (EVD outbreak is the largest, both by number of cases and geographical extension, and deadliest, recorded so far in medical history. The source of ebolaviruses for human index case(s in most outbreaks is presumptively associated with handling of bush meat or contact with fruit bats. Transmission among humans occurs easily when a person comes in contact with contaminated body fluids of patients, but our understanding of other transmission routes is still fragmentary. This review deals with the controversial issue of aerosol transmission of filoviruses.

  17. Aerosol Transmission of Filoviruses.

    Mekibib, Berhanu; Ariën, Kevin K

    2016-01-01

    Filoviruses have become a worldwide public health concern because of their potential for introductions into non-endemic countries through international travel and the international transport of infected animals or animal products. Since it was first identified in 1976, in the Democratic Republic of Congo (formerly Zaire) and Sudan, the 2013-2015 western African Ebola virus disease (EVD) outbreak is the largest, both by number of cases and geographical extension, and deadliest, recorded so far in medical history. The source of ebolaviruses for human index case(s) in most outbreaks is presumptively associated with handling of bush meat or contact with fruit bats. Transmission among humans occurs easily when a person comes in contact with contaminated body fluids of patients, but our understanding of other transmission routes is still fragmentary. This review deals with the controversial issue of aerosol transmission of filoviruses. PMID:27223296

  18. Dynamic lung transmission studies

    The aim of this study was to develop a non-invasive method for determining regional lungvolumes, which could replace bronchospirometry in routine clinical use. Transmission through the thorax of sup(99m)Tc-gammarays is measured by means of a gamma camera on line with a computer. The technique of measurement and data analysis is described and tested in several series of phantom studies. The results proved to be good: the mean difference with the real volumes was -4%. The error varied between -10% and +1. Transmission studies and bronchospirometry are compared in a group of 11 patients and there proved to be a good correspondence between the results of these methods. It is concluded that transmission experiments can determine the vital capacity of both lungs as a whole as accurately as spirometry and allows the measurement of vital capacity for each lung separately with the same accuracy as bronchospirometry. (Auth.)

  19. Transmission line capital costs

    The displacement or deferral of conventional AC transmission line installation is a key benefit associated with several technologies being developed with the support of the U.S. Department of Energy's Office of Energy Management (OEM). Previous benefits assessments conducted within OEM have been based on significantly different assumptions for the average cost per mile of AC transmission line. In response to this uncertainty, an investigation of transmission line capital cost data was initiated. The objective of this study was to develop a database for preparing preliminary estimates of transmission line costs. An extensive search of potential data sources identified databases maintained by the Bonneville Power Administration (BPA) and the Western Area Power Administration (WAPA) as superior sources of transmission line cost data. The BPA and WAPA data were adjusted to a common basis and combined together. The composite database covers voltage levels from 13.8 to 765 W, with cost estimates for a given voltage level varying depending on conductor size, tower material type, tower frame type, and number of circuits. Reported transmission line costs vary significantly, even for a given voltage level. This can usually be explained by variation in the design factors noted above and variation in environmental and land (right-of-way) costs, which are extremely site-specific. Cost estimates prepared from the composite database were compared to cost data collected by the Federal Energy Regulatory Commission (FERC) for investor-owned utilities from across the United States. The comparison was hampered because the only design specifications included with the FERC data were voltage level and line length. Working within this limitation, the FERC data were not found to differ significantly from the composite database. Therefore, the composite database was judged to be a reasonable proxy for estimating national average costs

  20. Bone Densitometry (Bone Density Scan)

    ... of DXA Bone Densitometry? What is a Bone Density Scan (DXA)? Bone density scanning, also called dual-energy x-ray absorptiometry ( ... is today's established standard for measuring bone mineral density (BMD). An x-ray (radiograph) is a noninvasive ...

  1. Transmission grid security

    Haarla, Liisa; Hirvonen, Ritva; Labeau, Pierre-Etienne

    2011-01-01

    In response to the growing importance of power system security and reliability, ""Transmission Grid Security"" proposes a systematic and probabilistic approach for transmission grid security analysis. The analysis presented uses probabilistic safety assessment (PSA) and takes into account the power system dynamics after severe faults. In the method shown in this book the power system states (stable, not stable, system breakdown, etc.) are connected with the substation reliability model. In this way it is possible to: estimate the system-wide consequences of grid faults; identify a chain of eve

  2. Viewing transmission issues in perspective

    This article examines electric power transmission from the perspective of the power producers. The article discusses the impact to transmission line routing policy of the health effects of, and public opinion about, electromagnetic fields. The author examines past pricing policy for transmission access and encourages the power producers and owners of transmission lines to become more involved in the regulatory process

  3. Viewing transmission issues in perspective

    Casazza, J.A.

    1993-10-01

    This article examines electric power transmission from the perspective of the power producers. The article discusses the impact to transmission line routing policy of the health effects of, and public opinion about, electromagnetic fields. The author examines past pricing policy for transmission access and encourages the power producers and owners of transmission lines to become more involved in the regulatory process.

  4. Towards magnetic resonance in scanning tunneling microscopy using heterodyne detection

    Peter, Moritz

    2015-01-01

    The present work introduces a new concept for magnetic resonance measurements in the GHz regime inside a scanning tunneling microscope. It is based on heterodyne detection in a spin-polarized tunneling barrier. The experimental requirements, including a new method to suppress transmission effects, are explained. Measurements on three model systems which were studied to validate the new technique are presented and compared to simulations.

  5. Scanning tunneling microscopy on rough surfaces: quantitative image analysis

    Reiss, Günter; Bruckl, Hubert; Vancea, Johann; Lecheler, R.; Hastreiter, E.

    1991-01-01

    In this communication, the application of scanning tunneling microscopy (STM) for a quantitative evaluation of roughnesses and mean island sizes of polycrystalline thin films is discussed. Provided strong conditions concerning the resolution are satisfied, the results are in good agreement with standard techniques as, for example, transmission electron microscopy. Owing to its high resolution, STM can supply a better characterization of surfaces than established methods, especially concerning...

  6. Beta attenuation transmission system (BATS)

    The beta attenuation transmission system (BATS) is an automated radiation gauge designed for quantitative measurement of component thickness in explosive detonators. The BATS was designed and built by Group M-1, the Nondestructive Testing Group, of the Los Alamos Scientific Laboratory to measure the areal thickness, in mg/cm2, of a cylinder of high explosive (HE) enclosed within a plastic holder. The problem is to determine the density of the HE. A 90Sr source is collimated by a 0.25 x 1.59-mm slit, and the transmitted beta-particle flux is detected by a plastic scintillator, coupled to a photomultiplier tube. The detonator is transported through the radiation beam by a leadscrew, ballnut, stepping-motor combination. Continuous analog position data are available, derived from the output from a linear-actuated potentiometer attached to the scanner. A linear electrometer amplifies the detected signal, which is then integrated for a preselected time, to obtain the desired statistical accuracy. A microprocessor (μP) is used to control the scanner position and to make the data readings at the assigned positions. The data are stored, and, at the completion of the scan, are processed into the desired format. The final answer is displayed to the operator or output to a peripheral device for permanent record. The characteristics of the radiation source, the collimator, the signal detection and conditioning, and the final results are described in detail. The scanner and the microprocessor control system are briefly outlined

  7. Beta attenuation transmission system (BATS)

    Hagan, R.C.; Fullbright, H.J.

    1977-01-01

    The beta attenuation transmission system (BATS) is an automated radiation gauge designed for quantitative measurement of component thickness in explosive detonators. The BATS was designed and built by Group M-1, the Nondestructive Testing Group, of the Los Alamos Scientific Laboratory to measure the areal thickness, in mg/cm/sup 2/, of a cylinder of high explosive (HE) enclosed within a plastic holder. The problem is to determine the density of the HE. A /sup 90/Sr source is collimated by a 0.25 x 1.59-mm slit, and the transmitted beta-particle flux is detected by a plastic scintillator, coupled to a photomultiplier tube. The detonator is transported through the radiation beam by a leadscrew, ballnut, stepping-motor combination. Continuous analog position data are available, derived from the output from a linear-actuated potentiometer attached to the scanner. A linear electrometer amplifies the detected signal, which is then integrated for a preselected time, to obtain the desired statistical accuracy. A microprocessor (..mu..P) is used to control the scanner position and to make the data readings at the assigned positions. The data are stored, and, at the completion of the scan, are processed into the desired format. The final answer is displayed to the operator or output to a peripheral device for permanent record. The characteristics of the radiation source, the collimator, the signal detection and conditioning, and the final results are described in detail. The scanner and the microprocessor control system are briefly outlined.

  8. Economical quantum anonymous transmissions

    We present a new information-theoretically secure protocol for the anonymous transmission of quantum information. Different from the pioneering works, we use single photons to construct anonymous entanglement instead of multi-partite entangled states in this protocol, and therefore we reduce the complexity of physical implementation in practice.

  9. Watching Handball Transmissions

    Frandsen, Kirsten

    2010-01-01

    competent when mastering the game and in relation to others. The study shows that entertainment concerns both affective involvement and identity formation, as social and cultural meaning seem to be at the root of involvement. Even though both men and women find great joy in the transmissions, their viewing...

  10. Improving Transmission Planning

    Saraswat, Kavita; Gupta, Amol

    2016-01-01

    Development of power transmission networks requires long lead times and substantial capital. Optimization of investment is especially critical in fast-growing economies such as India’s, where there are competing demands on financial resources, and utilities need to maintain adequate cash flow to expand electricity service for economic growth and poverty reduction. As shown by examples from...

  11. Dilemmas of Cultural Transmission

    Kováts-Németh, Mária

    2016-01-01

    The fundamental problem of the 21st century is that in the modern civilization "the transmission of values is not stable." There is nothing, except for the natural sense of justice and some legal traditions, which would exercise selective power on social behavior. At a critical time in 1949 Albert Szent-Györgyi drew the attention to the…

  12. Lidar arc scan uncertainty reduction through scanning geometry optimization

    H. Wang

    2015-10-01

    Full Text Available Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a fixed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction. Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind fluctuations and depends on the scan geometry (the arc span and the arc orientation. This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annual energy production. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with flat terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation when arc scans are used for wind resource assessment.

  13. Pott's disease: radioisotope scanning findings

    The study is aim was to describe findings in bone scan in patients with Pott's disease. Eight patients had a bone scan with 99mTc . The findings included: a spindle image due to increased uptake in vertebrae and intervertebral uptake in three cases, increased uptake in vertebrae in three cases, paravertebral uptake in one case and vertebral compression with diminished uptake in one case. Bone scan is a useful tool in evaluating spinal tuberculosis (Pott's disease) as an indicator of activity within the lesion. (authors)

  14. Pediatric pulmonary CT-scanning

    Forty three lung scans, obtained in 29 anaesthetized children, were evaluated and compared with 85 scans performed in 52 sedated children. Confluent high absorptive areas in the lower parts of the lungs were found in 35 (81%) of the scans performed in children under general aneasthesia but such areas were not found in the scans performed under sedation. For general anaesthesia, halothane-N2O-O2 was used in all but one patient. The radiological changes are presumably due to a fall in functional residual capacity with consequent airway closure. It is important not to misinterpret these anaesthesia-induced pulmonary changes which may obscure or mimic true pathological lesions, such as parenchymal and pleural metastases. (orig.)

  15. Establishing an Environmental Scanning Process.

    Morrison, James L.

    1985-01-01

    A formal environmental scanning system designed to identify emerging issues, events, or trends threatening or bringing opportunity to an institution is discussed that uses a committee to systematically collect and analyze data from a variety of sources. (MSE)

  16. Scanning electron microscopy of biomaterials

    McKinlay, K.J.; Scotchford, C A; Grant, D M; Oliver, J M; King, John R.; Brown, Paul D.

    2004-01-01

    A comparison of conventional high vacuum scanning electron microscopy (HVSEM), environmental SEM (ESEM) and confocal laser scanning microscopy (CLSM) in the assessment of cell-material interactions is made. The processing of cells cultured for conventional HVSEM leads to the loss of morphological features that are retained when using ESEM. The use of ESEM in conjunction with CLSM of the labeled cytoskeleton gives an indication of changes to the cell morphology as a consequence of incubation t...

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

    Kim, Suhyun, E-mail: u98kim@surface.phys.titech.ac.jp; Jung, Younheum; Kim, Joong Jung; Lee, Sunyoung; Lee, Haebum [Memory Analysis Science and Engineering Group, Samsung Electronics, San #16 Hwasung-city, Gyeonggi-Do 445-701 (Korea, Republic of); Kondo, Yukihito [EM Business Unit, JEOL Ltd., 3-1-2 Musashino, Akishima, Tokyo 196-8558 (Japan)

    2014-10-15

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

  18. Regional transmission subsystem planning

    Costa Bortoni, Edson da [Quadrante Softwares Especializados Ltda., Itajuba, MG (Brazil); Bajay, Sergio Valdir; Barros Correia, Paulo de [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica; Santos, Afonso Henriques Moreira; Haddad, Jamil [Escola Federal de Engenharia de Itajuba, MG (Brazil)

    1994-12-31

    This work presents an approach for the planning of transmission systems by employing mixed--integer linear programming to obtain a cost and operating characteristics optimized system. The voltage loop equations are written in a modified form, so that, at the end of the analysis, the model behaves as a DC power flow, with the help of the two Kirchhoff`s laws, exempting the need of interaction with an external power flow program for analysis of the line loading. The model considers the occurrence of contingencies, so that the final result is a network robust to the most severe contingencies. This whole technique is adapted to the regional electric power transmission subsystems. (author) 9 refs., 4 figs.

  19. ECRH transmission system

    The M.I.T. gyrotron group operates a 140 GHz, short pulse (1μs) gyrotron with output power, at present, of up to 175 kW. Output radiation has been obtained in several modes, including TE03 at 140 GHz, TE23 at 137 GHz, TE42 at 128 GHz and TE52 at 145 GHz. Studies have been carried out of the mode purity, both in frequency and in space, of gyrotron output radiation. These studies investigate parasitic mode excitation and mode conversion of gyrotron output power. Far field patterns of gyrotron radiation have been investigated to determine mode symmetry and purity. These results are useful in estimating the efficiency of various transmission systems. Finally, a new approach to quasi-optical transmission lines and mode converters, using axisymmetric optics, is suggested

  20. Data transmission networks

    Alexovich, Robert

    1990-01-01

    A task order was written by the High Resolution, High Frame Rate Video Technology (HHVT) project engineers to investigate data compression techniques that could be applied to the HHVT system, and both existing and planned downlink/uplink capabilities of the Space Shuttle and Space Station Freedom. The following tasks were included: (1) Investigate signal channel availability and determine both the maximum possible data rate and the average data rate; (2) Identify time blocks for HHVT video transmission assuming time sharing and interruptions in the communication links; (3) Determine the bit error rates to be expected; and (4) Define the transmit and receive interfaces. A summary chart of the data transmission capabilities for Tracking and Data Relay Satellite System (TDRSS), the Space Shuttle, Space Station Freedom, Spacelab, and USLab are also presented.

  1. Mechanisms, Transmissions and Applications

    Corves, Burkhard

    2012-01-01

    The first Workshop on Mechanisms, Transmissions and Applications -- MeTrApp-2011 was organized by the Mechatronics Department at the Mechanical Engineering Faculty, “Politehnica” University of Timisoara, Romania, under the patronage of the IFToMM Technical Committees Linkages and Mechanical Controls and Micromachines. The workshop brought together researchers and students who work in disciplines associated with mechanisms science and offered a great opportunity for scientists from all over the world to present their achievements, exchange innovative ideas and create solid international links, setting the trend for future developments in this important and creative field. The topics treated in this volume are mechanisms and machine design, mechanical transmissions, mechatronic and biomechanic applications, computational and experimental methods, history of mechanism and machine science and teaching methods.

  2. Global wireless power transmission

    Glaser, Peter E.

    1995-01-01

    Economic and environmental pressures require the development of technologies that are compatible with the Earth’s environment and acceptable to society. An emerging power supply option based on Nikola Tesla’s concept of wireless power transmission (WPT) can be applied to transmit power over intercontinental distances with power relay satellites (PRS) [1] to access renewable energy sources at undeveloped or underutilized remote sites, and to convert solar energy in space for use on Earth on a ...

  3. Control of schistosomiasis transmission

    Luiz C. de S. Dias; Oswaldo Marçal Jr.; GLASSER Carmem M.

    1995-01-01

    Despite the success of control programmes, schistosomiasis is still a serious public health problem in the world. More than 70 countries where 200 million individuals are evaluated to be infected of a total 600 million at risk. Though there have been important local success in the control of transmission, globally the infection has increased. Economic constrains in developing countries, environmental changes associated with migration and water resources development have been blocking the prog...

  4. Available transmission capacity assessment

    Škokljev Ivan

    2012-01-01

    Full Text Available Effective power system operation requires the analysis of vast amounts of information. Power market activities expose power transmission networks to high-level power transactions that threaten normal, secure operation of the power system. When there are service requests for a specific sink/source pair in a transmission system, the transmission system operator (TSO must allocate the available transfer capacity (ATC. It is common that ATC has a single numerical value. Additionally, the ATC must be calculated for the base case configuration of the system, while generation dispatch and topology remain unchanged during the calculation. Posting ATC on the internet should benefit prospective users by aiding them in formulating their requests. However, a single numerical value of ATC offers little for prospect for analysis, planning, what-if combinations, etc. A symbolic approach to the power flow problem (DC power flow and ATC offers a numerical computation at the very end, whilst the calculation beforehand is performed by using symbols for the general topology of the electrical network. Qualitative analysis of the ATC using only qualitative values, such as increase, decrease or no change, offers some new insights into ATC evaluation, multiple transactions evaluation, value of counter-flows and their impact etc. Symbolic analysis in this paper is performed after the execution of the linear, symbolic DC power flow. As control variables, the mathematical model comprises linear security constraints, ATC, PTDFs and transactions. The aim is to perform an ATC sensitivity study on a five nodes/seven lines transmission network, used for zonal market activities tests. A relatively complicated environment with twenty possible bilateral transactions is observed.

  5. Transmission of Helicobacter pylori

    Axon, Anthony T. R.

    1999-01-01

    Helicobacter gastroduodenitis is a serious chronic infectious disease that is responsible for widespread morbidity and mortality. An understanding of the way in which it spreads is fundamentally important when considering measures for its control. Its prevalence is highest in the developing world and in individuals with a disadvantaged socio-economic childhood. The disease is believed to be contracted during the early years of life. A faeco-oral mode of transmission is considered by many to b...

  6. Wireless Power Transmission

    Pragati S. Chawardol; Deepali R. Badre ,; , Mithul S. There

    2014-01-01

    A great concern has been voiced in recent years over the extensive use of energy, the limited supply of resourses, and the pollution of the environment from the use of present energy conversion systems. Electrical power accounts for much of the energy consumed. One of the major issue in power system is the losses occurs during the transmission and distribution of electrical power. As the demand increases day by day, the power generation increases and the power loss is also increas...

  7. Superconductive communication transmission

    Recent developments in superconducting techniques have made possible the application of superconductivity in communication cables. Extensive studies have been made, and several experimental coaxial lines and superconductive communication cables have been produced and tested. The attenuation and transmission capacities of superconductive coaxial lines are greatly improved compared with existing cables. Furthermore, the cost of superconductive communication cables is far less than that of existing cables. (author)

  8. Lidar arc scan uncertainty reduction through scanning geometry optimization

    Wang, Hui; Barthelmie, Rebecca J.; Pryor, Sara C.; Brown, Gareth.

    2016-04-01

    Doppler lidars are frequently operated in a mode referred to as arc scans, wherein the lidar beam scans across a sector with a fixed elevation angle and the resulting measurements are used to derive an estimate of the n minute horizontal mean wind velocity (speed and direction). Previous studies have shown that the uncertainty in the measured wind speed originates from turbulent wind fluctuations and depends on the scan geometry (the arc span and the arc orientation). This paper is designed to provide guidance on optimal scan geometries for two key applications in the wind energy industry: wind turbine power performance analysis and annual energy production prediction. We present a quantitative analysis of the retrieved wind speed uncertainty derived using a theoretical model with the assumption of isotropic and frozen turbulence, and observations from three sites that are onshore with flat terrain, onshore with complex terrain and offshore, respectively. The results from both the theoretical model and observations show that the uncertainty is scaled with the turbulence intensity such that the relative standard error on the 10 min mean wind speed is about 30 % of the turbulence intensity. The uncertainty in both retrieved wind speeds and derived wind energy production estimates can be reduced by aligning lidar beams with the dominant wind direction, increasing the arc span and lowering the number of beams per arc scan. Large arc spans should be used at sites with high turbulence intensity and/or large wind direction variation.

  9. Hepatobiliary scan in neonatal Jaundice

    Jaundice is more or less common in newborn babies. Through physiological jaundice is most common cause of neonatal jaundice, possibility of obstructive jaundice especially biliary atresia should be kept in mind. Early diagnosis of biliary atresia followed by surgical treatment can save baby's life. Otherwise death is inevitable due to liver failure. Hepatobiliary scan is the imaging study of choice in neonatal jaundice especially when there is persistent conjugated hyperbilirubinaemia. Total 27 newborn babies of suspected biliary atresia, aged 14 days to 4 months were referred to Institute of Nuclear Medicine for Hepatobiliary scan. All of them had high serum bilirubin ranged from 6.0 mg/dl with an average of 9.35 ng/dl serum bilirubin level. Ultrasonography of hepatobiliary system was performed in 14 cases showing normal sized liver in 4 cases and hepatomegaly in 10 cases. Hepatobiliary scan was done with 99mTc-Mebrofenin (Br IDA) after preparing the baby with phenobarbitone for 3-5 days. 20 (67%) cases were scan positive suggesting biliary atresia (BA) and 7(27%) cases were scan negative. In BA there will be increased hepatic uptake of the radionuclide without any significant excretion even in 24 hours delayed images. Presence of radiotracer in the bowel exclude the diagnosis of BA. Early diagnosis of biliary atresia is very important because in this condition surgery should be performed early (within 60 days of life). Studies suggest that hepatobiliary scan after hepatic stimulation with phenobarbitone for a period of 3-5 days is highly accurate for differentiating biliary atresia from other causes of neonatal jaundice. It is very important to perform hepatobiliary scan in a case of neonatal jaundice to exclude biliary atresia for the sake of baby's life.(author)

  10. Environmental Scanning and the Information Manager.

    Newsome, James; McInerney, Claire

    1990-01-01

    Discusses nine components of an environmental scanning model: selecting the scanning team; selecting resources to scan; choosing criteria for scanning; scanning the resources; identifying signals of new issues; selecting key events/issues; monitoring and analyzing events/issues; disseminating information; and deciding on appropriate organizational…

  11. Interesting bone scans - unusual findings

    Dobson, M.; Wadhwa, S.S.; Mansberg, R.; Fernandes, V.B. [Wollongong Hospital, Wollongong, NSW (Australia)

    1997-12-01

    A 59-year-old female with carcinoma of the colon and known liver metastatic disease was referred for bone scan to evaluate for bone metastases. Although no bone metastases were found, there was abnormal uptake noted in the liver corresponding to a metastatic calcified lesion. The only other findings were of degenerative disease in the cervical spine, right shoulder and small joints of the hands. A 69-year-old male with carcinoma of the prostate and right side low back pain was referred for bone scan. No focal abnormalities to suggest metastatic disease were identified; findings within the cervical spine, lumber spine and knees were presumed secondary to degenerative disease. Intermittent pain persisted and the patient was referred for a repeat bone scan six months later. Previous scan findings of degenerative disease and no metastatic disease were confirmed; however, closer inspection revealed an enlarged right kidney with significant retention of tracer in the pelvicalyceal system suggesting possible obstruction. A Retrograde pyelogram was performed, and no obvious obstruction demonstrated. As bone scan findings were very suggestive of obstruction, a DTPA scan with lasix was performed showing a dilated right collecting system with no functional obstruction. Given the degree of dilation, it is possible that the patient experiences intermittent PUJ obstruction causing his symptoms. A 33-year-old male with insulin dependent diabetes mellitus and viral arthritis was referred for a bone scan. A three phase revealed increased uptake in the region of the knee and leR proximal tibia. Delayed whole body images revealed multiple focal areas of osteoblastic activity in the leR tibia. Abnormal uptake was also seen in the upper third of the leR femur. The remainder of the skeletal survey was normal. X-ray correlation of the leR tibia and femoral findings was undertaken. Combinating unilateral changes on bone scan and X-ray although very suggestive of sclerotic polyostotic

  12. Interesting bone scans - unusual findings

    A 59-year-old female with carcinoma of the colon and known liver metastatic disease was referred for bone scan to evaluate for bone metastases. Although no bone metastases were found, there was abnormal uptake noted in the liver corresponding to a metastatic calcified lesion. The only other findings were of degenerative disease in the cervical spine, right shoulder and small joints of the hands. A 69-year-old male with carcinoma of the prostate and right side low back pain was referred for bone scan. No focal abnormalities to suggest metastatic disease were identified; findings within the cervical spine, lumber spine and knees were presumed secondary to degenerative disease. Intermittent pain persisted and the patient was referred for a repeat bone scan six months later. Previous scan findings of degenerative disease and no metastatic disease were confirmed; however, closer inspection revealed an enlarged right kidney with significant retention of tracer in the pelvicalyceal system suggesting possible obstruction. A Retrograde pyelogram was performed, and no obvious obstruction demonstrated. As bone scan findings were very suggestive of obstruction, a DTPA scan with lasix was performed showing a dilated right collecting system with no functional obstruction. Given the degree of dilation, it is possible that the patient experiences intermittent PUJ obstruction causing his symptoms. A 33-year-old male with insulin dependent diabetes mellitus and viral arthritis was referred for a bone scan. A three phase revealed increased uptake in the region of the knee and leR proximal tibia. Delayed whole body images revealed multiple focal areas of osteoblastic activity in the leR tibia. Abnormal uptake was also seen in the upper third of the leR femur. The remainder of the skeletal survey was normal. X-ray correlation of the leR tibia and femoral findings was undertaken. Combinating unilateral changes on bone scan and X-ray although very suggestive of sclerotic polyostotic

  13. The boundary-scan handbook

    Parker, Kenneth P

    2016-01-01

    Aimed at electronics industry professionals, this 4th edition of the Boundary Scan Handbook describes recent changes to the IEEE1149.1 Standard Test Access Port and Boundary-Scan Architecture. This updated edition features new chapters on the possible effects of the changes on the work of the practicing test engineers and the new 1149.8.1 standard. Anyone needing to understand the basics of boundary scan and its practical industrial implementation will need this book. Provides an overview of the recent changes to the 1149.1 standard and the effect of the changes on the work of test engineers;   Explains the new IEEE 1149.8.1 subsidiary standard and applications;   Describes the latest updates on the supplementary IEEE testing standards. In particular, addresses: IEEE Std 1149.1                      Digital Boundary-Scan IEEE Std 1149.4                      Analog Boundary-Scan IEEE Std 1149.6                      Advanced I/O Testing IEEE Std 1149.8.1           �...

  14. Diagnosis of spatial resolution for microbeam scanning PIXE using STIM method and CR-39 track detector in PASTA

    In PIXE analysis system and Tandem Accelerator facility (PASTA) of NIRS, we are using Scanning Transmission Ion Microscopy (STIM) method and solid track detector to diagnose the spatial resolution of scanning microbeam PIXE analysis system. These methods are widely used by many microbeam facilities. (author)

  15. Simulation of scanning tunneling spectroscopy of supported carbon nanotubes

    The angle and energy dependent transmission of wave packets was calculated through a jellium potential model of a scanning tunneling microscope (STM) junction containing different arrangements of carbon nanotubes. The total tunnel current as a function of STM bias was calculated by statistical averaging over a distribution of wave packets in the allowed energy window. Three tunneling situations were studied: (i) a STM tunnel junction with no nanotube present, (ii) one single wall nanotube in the STM junction, and (iii) a nanotube 'raft'. The effects of point contacts at the STM tip/nanotube, at the nanotube/substrate, and at both interfaces were also investigated. The theory allowed us to identify components of pure geometrical origin responsible for the asymmetry in the scanning tunneling spectroscopy (STS) spectrum of the carbon nanotubes with respect to bias voltage polarity. The calculations show that for tip negative bias the angular dependence of the transmission is determined by the tip shape. The particular tip shape introduces an asymmetry on the negative side of the STS spectrum. For tip positive bias the angular dependence of the transmission depends strongly on the nature of the nanosystem in the STM gap. While the transmission of the STM tunnel junction with no nanotube present can be well represented by a one dimensional model, all other geometries cause a large normal-transverse momentum mixing of the wave packet. A diffraction-grating-like behavior is seen in the angular dependence of the transmission of the nanotube raft. Point contacts between the nanotube and the substrate cause an asymmetry in the positive side of the STS spectrum. Calculated STS spectra are compared to experimental ones

  16. Quantum Contact Transmission

    崔迪

    2015-01-01

    Abstract:Quantum transmission is based on quantum entanglement, which is a kind of the phenomenon of quantum mechanics. Quantum object refers to two or more between the localized, the classic strong correlation. When two object quantum entanglement in the quantum state is not independent, but related, and the correlation distance, a pair of electronic of entanglement state, no matter how far apart, they spin direction will remain an up and a down. If one of the electronic spin direction is changed, another of the electron spin direction wil follow to change immediately.

  17. Research and Transmission

    Denise Pumain

    2001-01-01

    Full Text Available The present situation provides a challenge for us to reconsider the necessary link between science and pedagogy, between research and the transmission of knowledge. The Ministry of National education has just inaugurated a broad consultation of teachers on every level with a view to modernising and giving coherence to the programs of secondary education. Armand Frémont will head the group of experts responsible for history and geography. Is this a coincidence? The changeover in the jury for t...

  18. Coaxial transmission line - Equalization

    The transmission of electrical signal through a coaxial line is not perfect and signal distortions are increased as much as the frequency spectrum is extended. We have designed and achieved passive filters (named equalizers) with transfer functions which are inverse of coaxial transfer functions. Doing so our attempt is to avoid definitive loss of information in the recorded data. The main feature of our equalization method lies in the fact it could be either an electrical or a numerical correction or both of them. Some examples in the use of this technique are also proposed

  19. Dose-rate controlled energy dispersive x-ray spectroscopic mapping of the metallic components in a biohybrid nanosystem

    Zhu, Yuanyuan; Munro, Catherine J.; Olszta, Matthew J.; Edwards, Danny J.; Braunschweig, Adam B.; Knecht, Marc R.; Browning, Nigel D.

    2016-08-01

    In this work, we showcase that through precise control of the electron dose rate, state-of-the-art large solid angle energy dispersive x-ray spectroscopy mapping in aberration-corrected scanning transmission electron microscope is capable of faithful and unambiguous chemical characterization of the Pt and Pd distribution in a peptide-mediated nanosystem. This low-dose-rate recording scheme adds another dimension of flexibility to the design of elemental mapping experiments, and holds significant potential for extending its application to a wide variety of beam sensitive hybrid nanostructures.

  20. Atomic structure and growth mechanism of T1 precipitate in Al–Cu–Li–Mg–Ag alloy

    The atomic structure of a 0.94-nm-thick T1 precipitate in an Al–Cu–Li–Mg–Ag alloy is investigated by combining aberration-corrected scanning transmission electron microscopy (STEM) and energy-dispersive X-ray spectroscopy (EDX). Ag segregates at the first layer of the T1 precipitate interface, revealing a significant compositional variation of Ag throughout the interface. Moreover, the T1 precipitate thickened from 0.94 nm with successive stacking of identical 0.94 nm thick layers

  1. Local stabilisation of polar order at charged antiphase boundaries in antiferroelectric (Bi0.85Nd0.15(Ti0.1Fe0.9O3

    Ian MacLaren

    2013-08-01

    Full Text Available Observation of an unusual, negatively-charged antiphase boundary in (Bi0.85Nd0.15(Ti0.1Fe0.9O3 is reported. Aberration corrected scanning transmission electron microscopy is used to establish the full three dimensional structure of this boundary including O-ion positions to ∼±10 pm. The charged antiphase boundary stabilises tetragonally distorted regions with a strong polar ordering to either side of the boundary, with a characteristic length scale determined by the excess charge trapped at the boundary. Far away from the boundary the crystal relaxes into the well-known Nd-stabilised antiferroelectric phase.

  2. Mechanism of coercivity enhancement by Ag addition in FePt-C granular films for heat assisted magnetic recording media

    We investigated the Ag distribution in a FePtAg-C granular film that is under consideration for a heat assisted magnetic recording medium by aberration-corrected scanning transmission electron microscope-energy dispersive X-ray spectroscopy and X-ray absorption fine structure. Ag is rejected from the core of FePt grains during the deposition, forming Ag-enriched shell surrounding L10-ordered FePt grains. Since Ag has no solubility in both Fe and Pt, the rejection of Ag induces atomic diffusions thereby enhancing the kinetics of the L10-order in the FePt grains

  3. Atomic-resolution electron energy loss studies of precipitates in an Al–Mg–Si–Cu–Ag alloy

    Aberration-corrected scanning transmission electron microscopy combined with electron energy loss spectroscopy has been used to determine the distribution of Cu and Ag atomic columns of precipitates in an Al–Mg–Si–Cu–Ag alloy. Cu columns were commonly part of C and Q′ phases, with the atomic columns having large projected separations. Columns containing Ag were more tightly spaced, in areas lacking repeating unit cells and at incoherent precipitate–host lattice interfaces. Cu-rich and Ag-rich areas were not found to intermix

  4. What Is a Nuclear Heart Scan?

    ... from the NHLBI on Twitter. What Is a Nuclear Heart Scan? A nuclear heart scan is a test that provides important ... use it to create pictures of your heart. Nuclear heart scans are used for three main purposes: ...

  5. Calculation of Uniform of Beam Scanning

    2011-01-01

    For the electron beam application, it is always scanned by a dipole magnet. The uniform of the scanning has great influence for some application, such as the irradiation of the thyristor. There are two methods for improving the scanning uniform:

  6. Linking world scan and image

    In march 1994 the Central Planning Bureau (CPB) in the Hague, the National Institute of Public Health and Environmental Protection (RIVM) in Bilthoven and the Institute of Environmental Studies (IES) in Amsterdam started the first phase of a joint research program aimed at creating integrated scenarios of the global economy, GHG emissions, and climate impacts. The goal of the first phase of this project was to design and test a linked version of the economic model WORLD SCAN of the former, and the climate model IMAGE 2 of the latter institute. This first phase has resulted in the planned test runs with an operational version of the linked models by May 1995. The experiences in the first year were encouraging, both in the scientific and the organizational sense. In a sense, a link was made between scientific disciplines: a coupling of disciplines concerning with global economic development and the global physical climate system is difficult and novel. The goal of the project was to integrate long-term economic developments and effects of climate change. Both the WORLD SCAN model and IMAGE 2 provide a consistent analysis of the global system, but from different perspectives. IMAGE 2 simulates climate change and its effects in a global context but treats the economic system as exogenous. WORLD SCAN covers the world economic system in a consistent manner but does not take into account the global environment. The links are constructed in the area of agriculture and energy. The basic idea is that WORLD SCAN determines demand and supply on economic principles, while IMAGE 2 provides information on changes of land area and average quality of productive land, and other damage costs based on its three sub-systems. The demand for energy is fed into IMAGE 2's Energy Industry subsystem (EIS), which in turn determines emissions of greenhouse gases. Furthermore, some additional output from WORLD SCAN on activity levels, prices and capital structure can be used to determine

  7. Children, CT Scan and Radiation

    Morteza Bajoghli; Farshad Bajoghli; Nazila Tayari; Reza Rouzbahani

    2010-01-01

    Children are more sensitive to radiation than adults. Computer-ized tomography (CT) consists of 25 % of all medical imaging. It was estimated that more than 2% of all carcinomas in the USA are due to CT scans. There is an ongoing focus on the reduction of CT scan radiation dose. Awareness about risk-benefits of CT has increased. Reduction of radiological exam is an important issue because the accumulation effects of radiation can be hazardous. In addition, proper protocol should be followed f...

  8. RPC High Voltage Scan 2015

    CMS Collaboration

    2016-01-01

    During the LS1 the CMS RPC system has been upgraded with 144 new chambers installed on the forth endcap stations. An annual HV (RPC efficiency vs HV) scan for the entire RPC system has been performed during the Run2 data taking period in 2015. The obtained results have been compared to the HV scans performed in 2011 and 2012. No significant differences are observed in the compared results. The optimal HV working points for the newly installed chambers have been evaluated for the first time with collision data.

  9. Producing colour pictures from SCAN

    The computer code SCAN.TSK has been written for use on the Interdata 7/32 minicomputer which will convert the pictures produced by the SCAN program into colour pictures on a colour graphics VDU. These colour pictures are a more powerful aid to detecting errors in the MONK input data than the normal lineprinter pictures. This report is intended as a user manual for using the program on the Interdata 7/32, and describes the method used to produce the pictures and gives examples of JCL, input data and of the pictures that can be produced. (U.K.)

  10. Multifunction Digital Research Scanning System

    The multifunction digital research scanning system is a modularly constructed organ visualization system. The design objective of this system is quantification of organ visualization data, i.e. μCi/g. It is a high-speed (500 cm/min), 14-crystal, digital rectilinear scanner built as a special-purpose hard-wired computer. The two synchronous detector heads, one beneath and one above the scantable, each consisting of a linear array of seven, 3-in. x 2-in. NaI(Tl) crystals, each crystal having its own focused collimator. Each 7-detector array can be independently moved in the vertical direction. The exact position of the detectors is known at all times by the use of an absolute 13-bit shaft angle encoder along the longitudinal axis of the scantable and a programmable SloSyn motor across the table. Anatomical landmarks may be programmed into the system and automatically recognized when the detector passes over these points. The scan field is 198 cm long by 62 cm wide with a position resolution of 0.14 cm. The primary scan motion is along the longitudinal axis of the table and the detectors are indexed across the table. The scan image is built up seven lines at a time, allowing the total scanfield to be visualized with each pass of the detectors. Each crystal has its own 8-bit or 12-bit counter with buffer storage. A single fast pulse-height analyser (200 nsec. random pulse-pair resolution) is used for all 14 crystals using a time-sharing 'cueing' technique. The major components of the system consist of the mechanical scanning frame and position encoders; radiation detectors, coincidence circuitry and nuclear instrumentation; counters and buffer storage; anatomical landmark recognition section; arithmetic section; program control logic; system control logic; output control logic and the output devices. At present, the output devices consist of digital cathode-ray tubes, a storage scope, an IBM l/O writer and a Kennedy incremental read-write magnetic tape recorder. This

  11. Full-color holographic 3D imaging system using color optical scanning holography

    Kim, Hayan; Kim, You Seok; Kim, Taegeun

    2016-06-01

    We propose a full-color holographic three-dimensional imaging system that composes a recording stage, a transmission and processing stage and reconstruction stage. In recording stage, color optical scanning holography (OSH) records the complex RGB holograms of an object. In transmission and processing stage, the recorded complex RGB holograms are transmitted to the reconstruction stage after conversion to off-axis RGB holograms. In reconstruction stage, the off-axis RGB holograms are reconstructed optically.

  12. Airborne transmission of lyssaviruses.

    Johnson, N; Phillpotts, R; Fooks, A R

    2006-06-01

    In 2002, a Scottish bat conservationist developed a rabies-like disease and subsequently died. This was caused by infection with European bat lyssavirus 2 (EBLV-2), a virus closely related to Rabies virus (RABV). The source of this infection and the means of transmission have not yet been confirmed. In this study, the hypothesis that lyssaviruses, particularly RABV and the bat variant EBLV-2, might be transmitted via the airborne route was tested. Mice were challenged via direct introduction of lyssavirus into the nasal passages. Two hours after intranasal challenge with a mouse-adapted strain of RABV (Challenge Virus Standard), viral RNA was detectable in the tongue, lungs and stomach. All of the mice challenged by direct intranasal inoculation developed disease signs by 7 days post-infection. Two out of five mice challenged by direct intranasal inoculation of EBLV-2 developed disease between 16 and 19 days post-infection. In addition, a simple apparatus was evaluated in which mice could be exposed experimentally to infectious doses of lyssavirus from an aerosol. Using this approach, mice challenged with RABV, but not those challenged with EBLV-2, were highly susceptible to infection by inhalation. These data support the hypothesis that lyssaviruses, and RABV in particular, can be spread by airborne transmission in a dose-dependent manner. This could present a particular hazard to personnel exposed to aerosols of infectious RABV following accidental release in a laboratory environment. PMID:16687600

  13. Broadband transmission EPR spectroscopy.

    Wilfred R Hagen

    Full Text Available EPR spectroscopy employs a resonator operating at a single microwave frequency and phase-sensitive detection using modulation of the magnetic field. The X-band spectrometer is the general standard with a frequency in the 9-10 GHz range. Most (biomolecular EPR spectra are determined by a combination of the frequency-dependent electronic Zeeman interaction and a number of frequency-independent interactions, notably, electron spin - nuclear spin interactions and electron spin - electron spin interactions, and unambiguous analysis requires data collection at different frequencies. Extant and long-standing practice is to use a different spectrometer for each frequency. We explore the alternative of replacing the narrow-band source plus single-mode resonator with a continuously tunable microwave source plus a non-resonant coaxial transmission cell in an unmodulated external field. Our source is an arbitrary wave digital signal generator producing an amplitude-modulated sinusoidal microwave in combination with a broadband amplifier for 0.8-2.7 GHz. Theory is developed for coaxial transmission with EPR detection as a function of cell dimensions and materials. We explore examples of a doublet system, a high-spin system, and an integer-spin system. Long, straigth, helical, and helico-toroidal cells are developed and tested with dilute aqueous solutions of spin label hydroxy-tempo. A detection limit of circa 5 µM HO-tempo in water at 800 MHz is obtained for the present setup, and possibilities for future improvement are discussed.

  14. Localizing Test Power Consumption for Scan Testing

    XIANG Dong; LI Kai-wei

    2005-01-01

    A two stage scan architecture is proposed to do low powerand low test application cost scan testing. The first stage includes multiple scan chains, where each scan chain is driven by a primary input. Each scan flip-flop in the multiple scan chains drives a group of scan flip-flops. The scan flip-flop in the multiple scan chain and the scan flipflop driven by it are assigned the same values for all test vectors. Scan flip-flops in the multiple scan chains and those in the second stage use separate clock signals, but the design for testability technqiue needs only one clock. The proposed scan architecture localizes test power consumption to the multiple scan chains during test application. Test signals assigned to scan flip-flops in the multiple scan chains are applied to the scan flip-flops in the second stage after the test vector has been applied to the multiple scan chains. This technique can make test power consumption very small.

  15. Epidermal growth factor receptor subunit locations determined in hydrated cells with environmental scanning electron microscopy

    Peckys, Diana B.; Jean-Pierre Baudoin; Magdalena Eder; Ulf Werner; Niels de Jonge

    2013-01-01

    Imaging single epidermal growth factor receptors (EGFR) in intact cells is presently limited by the available microscopy methods. Environmental scanning electron microscopy (ESEM) of whole cells in hydrated state in combination with specific labeling with gold nanoparticles was used to localize activated EGFRs in the plasma membranes of COS7 and A549 cells. The use of a scanning transmission electron microscopy (STEM) detector yielded a spatial resolution of 3 nm, sufficient to identify the l...

  16. Broadband antenna with frequency scanning

    A. A. Shekaturin

    2014-06-01

    Full Text Available Relevance of this study. The main advantage of frequency scanning is simplicity of implementation. At this point, multifunctional usage of microwave modules is an urgent task, as well as their maximum simpler and cheaper. Antenna design and operation. The study is aimed at providing electric antenna with frequency scanning. It was based on the log-periodic antenna due to its wideband and negotiation capability over the entire operating frequency range. For this distribution line is bent in an arc of a circle in a plane blade while vibrators are arranged along the radius. Computer modeling of antennas with frequency scanning. Modeled with a non-mechanical motion antenna beam emitters representing system for receiving a radio frequency signal on mobile objects calculated for 1.8 GHz ... 4.2 GHz. The simulation was performed in a software environment for numerical modeling of electromagnetic «Feko 5.5». Analysis of the interaction of radiation is based on the method of moments. Findings. The result of this work is to propose a new design of the antenna with a frequency scanning method as agreed in a wide frequency range. In the studied technical solution provided by the rotation of NAM in the frequency range, and the matching of the antenna to the feed line is maintained. Application of this type of antennas on the proposed technical solution in communication systems will improve the communication reliability by maintaining coordination in the frequency range

  17. Introduction to scanning tunneling microscopy

    Chen, C Julian

    2008-01-01

    The scanning tunneling and the atomic force microscope, both capable of imaging individual atoms, were crowned with the Physics Nobel Prize in 1986, and are the cornerstones of nanotechnology today. This is a thoroughly updated version of this 'bible' in the field.

  18. Pulmonary ventilation/perfusion scan

    ... Critical Care, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team. Related MedlinePlus Health Topics COPD Lung Diseases Nuclear Scans Pulmonary Embolism Browse the Encyclopedia A.D. ...

  19. Developing an Environmental Scanning System.

    Morrison, James L.

    A step-by-step approach is provided for developing an environmental scanning system for colleges and universities to assist them in planning for the future. The objectives of such a system are to detect social, scientific, economic, technical, and political interactions important to the organization; define potential threats and opportunities from…

  20. Environmental Scanning, Vancouver Community College.

    Yao, Min

    This 1994 environmental scanning report from Vancouver Community College (VCC) reviews the expected effects of the separation of VCC into a new Vancouver Community College and Langara College (LC). The report examines the projected service area student-intake capacity; student characteristics; population growth trends; other postsecondary…