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Sample records for aberration-corrected high-resolution transmission

  1. Separating strain from composition in unit cell parameter maps obtained from aberration corrected high resolution transmission electron microscopy imaging

    SciTech Connect

    Schulz, T.; Remmele, T.; Korytov, M.; Markurt, T.; Albrecht, M.; Duff, A.; Lymperakis, L.; Neugebauer, J.; Chèze, C.

    2014-01-21

    Based on the evaluation of lattice parameter maps in aberration corrected high resolution transmission electron microscopy images, we propose a simple method that allows quantifying the composition and disorder of a semiconductor alloy at the unit cell scale with high accuracy. This is realized by considering, next to the out-of-plane, also the in-plane lattice parameter component allowing to separate the chemical composition from the strain field. Considering only the out-of-plane lattice parameter component not only yields large deviations from the true local alloy content but also carries the risk of identifying false ordering phenomena like formations of chains or platelets. Our method is demonstrated on image simulations of relaxed supercells, as well as on experimental images of an In{sub 0.20}Ga{sub 0.80}N quantum well. Principally, our approach is applicable to all epitaxially strained compounds in the form of quantum wells, free standing islands, quantum dots, or wires.

  2. Aberration corrected Lorentz scanning transmission electron microscopy.

    PubMed

    McVitie, S; McGrouther, D; McFadzean, S; MacLaren, D A; O'Shea, K J; Benitez, M J

    2015-05-01

    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.

  3. Restoring defect structures in 3C-SiC/Si (001) from spherical aberration-corrected high-resolution transmission electron microscope images by means of deconvolution processing.

    PubMed

    Wen, C; Wan, W; Li, F H; Tang, D

    2015-04-01

    The [110] cross-sectional samples of 3C-SiC/Si (001) were observed with a spherical aberration-corrected 300 kV high-resolution transmission electron microscope. Two images taken not close to the Scherzer focus condition and not representing the projected structures intuitively were utilized for performing the deconvolution. The principle and procedure of image deconvolution and atomic sort recognition are summarized. The defect structure restoration together with the recognition of Si and C atoms from the experimental images has been illustrated. The structure maps of an intrinsic stacking fault in the area of SiC, and of Lomer and 60° shuffle dislocations at the interface have been obtained at atomic level.

  4. Local symmetry breaking of a thin crystal structure of β-Si3N4 as revealed by spherical aberration corrected high-resolution transmission electron microscopy images.

    PubMed

    Kim, Hwang Su; Zhang, Zaoli; Kaiser, Ute

    2012-06-01

    This report is an extension of the study for structural imaging of 5-6 nm thick β-Si(3)N(4) [0001] crystal with a spherical aberration corrected transmission electron microscope by Zhang and Kaiser [2009. Structure imaging of β-Si(3)N(4) by spherical aberration-corrected high-resolution transmission electron microscopy. Ultramicroscopy 109, 1114-1120]. In this work, a local symmetry breaking with an uneven resolution of dumbbells in the six-membered rings revealed in the reported images in the study of Zhang and Kaiser has been analyzed in detail. It is found that this local asymmetry in the image basically is not relevant to a slight mistilt of the specimen and/or a beam tilt (coma). Rather the certain variation of the tetrahedral bond length of Si-N(4) in the crystal structure is found to be responsible for the uneven resolution with a local structural variation from region to region. This characteristic of the variation is also supposed to give a distorted lattice of apparently 2°-2.5° deviations from the perfect hexagonal unit cell as observed in the reported image in the work of Zhang and Kaiser. It is discussed that this variation may prevail only in a thin specimen with a thickness ranging ~≤ 5-6 nm. At the same time, it is noted that the average of the bond length variation is close to the fixed length known in a bulk crystal of β-Si(3)N(4).

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

    NASA Astrophysics Data System (ADS)

    Wen, C.; Ge, B. H.; Cui, Y. X.; Li, F. H.; Zhu, J.; Yu, R.; Cheng, Z. Y.

    2014-11-01

    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 ɛxx and ɛyy, 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 ɛxx and ɛyy 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.

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

    SciTech Connect

    Wen, C.; Ge, B. H.; Cui, Y. X.; Li, F. H.; Zhu, J.; Yu, R.; Cheng, Z. Y.

    2014-11-15

    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 ε{sub xx} and ε{sub yy}, 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 ε{sub xx} and ε{sub yy} 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.

  7. Nanowire growth kinetics in aberration corrected environmental transmission electron microscopy

    DOE PAGES

    Chou, Yi -Chia; Panciera, Federico; Reuter, Mark C.; Stach, Eric A.; Ross, Frances M.

    2016-03-15

    Here, we visualize atomic level dynamics during Si nanowire growth using aberration corrected environmental transmission electron microscopy, and compare with lower pressure results from ultra-high vacuum microscopy. We discuss the importance of higher pressure observations for understanding growth mechanisms and describe protocols to minimize effects of the higher pressure background gas.

  8. Studying Atomic Structures by Aberration-Corrected Transmission Electron Microscopy

    NASA Astrophysics Data System (ADS)

    Urban, Knut W.

    2008-07-01

    Seventy-five years after its invention, transmission electron microscopy has taken a great step forward with the introduction of aberration-corrected electron optics. An entirely new generation of instruments enables studies in condensed-matter physics and materials science to be performed at atomic-scale resolution. These new possibilities are meeting the growing demand of nanosciences and nanotechnology for the atomic-scale characterization of materials, nanosynthesized products and devices, and the validation of expected functions. Equipped with electron-energy filters and electron-energy loss spectrometers, the new instruments allow studies not only of structure but also of elemental composition and chemical bonding. The energy resolution is about 100 milli electron volts, and the accuracy of spatial measurements has reached a few picometers. However, understanding the results is generally not straightforward and only possible with extensive quantum-mechanical computer calculations.

  9. Studying atomic structures by aberration-corrected transmission electron microscopy.

    PubMed

    Urban, Knut W

    2008-07-25

    Seventy-five years after its invention, transmission electron microscopy has taken a great step forward with the introduction of aberration-corrected electron optics. An entirely new generation of instruments enables studies in condensed-matter physics and materials science to be performed at atomic-scale resolution. These new possibilities are meeting the growing demand of nanosciences and nanotechnology for the atomic-scale characterization of materials, nanosynthesized products and devices, and the validation of expected functions. Equipped with electron-energy filters and electron-energy-loss spectrometers, the new instruments allow studies not only of structure but also of elemental composition and chemical bonding. The energy resolution is about 100 milli-electron volts, and the accuracy of spatial measurements has reached a few picometers. However, understanding the results is generally not straightforward and only possible with extensive quantum-mechanical computer calculations. PMID:18653874

  10. High-resolution microspectrometer with an aberration-correcting planar grating.

    PubMed

    Grabarnik, Semen; Emadi, Arvin; Wu, Huaiwen; de Graaf, Ger; Wolffenbuttel, Reinoud F

    2008-12-01

    A concept for a highly miniaturized spectrometer featuring a two-component design is presented. The first component is a planar chip that integrates an input slit and aberration-correcting diffraction grating with an image sensor and is fabricated using microelectromechanical systems (MEMS) technologies. Due to the fabrication in a simple MEMS batch process the essential elements of the spectrometer are automatically aligned, and a low fabrication cost per device can be achieved. The second component is a spherical mirror, which is the only external part. The optimized grating structure compensates for aberrations within the spectrometer operating range, resulting in a diffraction-limited performance of the spectrometer optics. The prototype of the device has been fabricated and characterized. It takes a volume of 0.5 cm(3) and provides a FWHM spectral resolution of 0.7 nm over a 350 nm bandwidth from 420 nm to 770 nm combined with an etendue of 7.4x10(-5) mm(2) sr. PMID:19037373

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

    SciTech Connect

    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.

  12. Sub-Angstrom Low Voltage Performance of a Monochromated, Aberration-Corrected Transmission Electron Microscope

    PubMed Central

    Bell, David C.; Russo, Christopher J.; Benner, Gerd

    2011-01-01

    Lowering the electron energy in the transmission electron microscope allows for a significant improvement in contrast of light elements, and reduces knock-on damage for most materials. If low-voltage electron microscopes are defined as those with accelerating voltages below 100 kV, the introduction of aberration correctors and monochromators to the electron microscope column enables Ångstrom-level resolution, which was previously reserved for higher voltage instruments. Decreasing electron energy has three important advantages: 1) knock-on damage is lower, which is critically important for sensitive materials such as graphene and carbon nanotubes; 2) cross sections for electron-energy-loss spectroscopy increase, improving signal-to-noise for chemical analysis; 3) elastic scattering cross sections increase, improving contrast in high-resolution, zero-loss images. The results presented indicate that decreasing the acceleration voltage from 200 kV to 80 kV in a monochromated, aberration-corrected microscope enhances the contrast while retaining sub-angstrom resolution. These improvements in low-voltage performance are expected to produce many new results and enable a wealth of new experiments in materials science. PMID:20598206

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

    PubMed

    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.

  14. In situ observation on hydrogenation of Mg-Ni films using environmental transmission electron microscope with aberration correction

    SciTech Connect

    Matsuda, Junko; Yoshida, Kenta; Sasaki, Yukichi; Uchiyama, Naoki; Akiba, Etsuo

    2014-08-25

    In situ transmission electron microscopy (TEM) was performed to observe the hydrogenation of Mg-Ni films in a hydrogen atmosphere of 80–100 Pa. An aberration-corrected environmental TEM with a differential pumping system allows us to reveal the Angstrom-scale structure of the films in the initial stage of hydrogenation: first, nucleation and growth of Mg{sub 2}NiH{sub 4} crystals with a lattice spacing of 0.22 nm in an Mg-rich amorphous matrix of the film occurs within 20 s after the start of the high-resolution observation, then crystallization of MgH{sub 2} with a smaller spacing of 0.15 nm happens after approximately 1 min. Our in situ TEM method is also applicable to the analysis of other hydrogen-related materials.

  15. Impact of dynamical scattering on quantitative contrast for aberration-corrected transmission electron microscope images.

    PubMed

    Wen, C; Smith, David J

    2016-10-01

    Aberration-corrected transmission electron microscope images taken under optimum-defocus conditions or processed offline can correctly reflect the projected crystal structure with atomic resolution. However, dynamical scattering, which will seriously influence image contrast, is still unavoidable. Here, the multislice image simulation approach was used to quantify the impact of dynamical scattering on the contrast of aberration-corrected images for a 3C-SiC specimen with changes in atomic occupancy and thickness. Optimum-defocus images with different spherical aberration (CS) coefficients, and structure images restored by deconvolution processing, were studied. The results show that atomic-column positions and the atomic occupancy for SiC 'dumbbells' can be determined by analysis of image contrast profiles only below a certain thickness limit. This limit is larger for optimum-defocus and restored structure images with negative CS coefficient than those with positive CS coefficient. The image contrast of C (or Si) atomic columns with specific atomic occupancy changes differently with increasing crystal thickness. Furthermore, contrast peaks for C atomic columns overlapping with neighboring peaks of Si atomic columns with varied Si atomic occupancy, which is enhanced with increasing crystal thickness, can be neglected in restored structure images, but the effect is substantial in optimum-defocus images.

  16. The three-dimensional point spread function of aberration-corrected scanning transmission electron microscopy.

    PubMed

    Lupini, Andrew R; de Jonge, Niels

    2011-10-01

    Aberration correction reduces the depth of field in scanning transmission electron microscopy (STEM) and thus allows three-dimensional (3D) imaging by depth sectioning. This imaging mode offers the potential for sub-Ångstrom lateral resolution and nanometer-scale depth sensitivity. For biological samples, which may be many microns across and where high lateral resolution may not always be needed, optimizing the depth resolution even at the expense of lateral resolution may be desired, aiming to image through thick specimens. Although there has been extensive work examining and optimizing the probe formation in two dimensions, there is less known about the probe shape along the optical axis. Here the probe shape is examined in three dimensions in an attempt to better understand the depth resolution in this mode. Examples are presented of how aberrations change the probe shape in three dimensions, and it is found that off-axial aberrations may need to be considered for focal series of large areas. It is shown that oversized or annular apertures theoretically improve the vertical resolution for 3D imaging of nanoparticles. When imaging nanoparticles of several nanometer size, regular STEM can thereby be optimized such that the vertical full-width at half-maximum approaches that of the aberration-corrected STEM with a standard aperture.

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

    SciTech Connect

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

    2006-01-01

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

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Identification of light elements in silicon nitride by aberration-corrected scanning transmission electron microscopy.

    PubMed

    Idrobo, Juan C; Walkosz, Weronika; Klie, Robert F; Oğüt, Serdar

    2012-12-01

    In silicon nitride structural ceramics, the overall mechanical and thermal properties are controlled by the atomic and electronic structures at the interface between the ceramic grains and the amorphous intergranular films (IGFs) formed by various sintering additives. In the last ten years the atomic arrangements of heavy elements (rare-earths) at the Si(3)N(4)/IGF interfaces have been resolved. However, the atomic position of light elements, without which it is not possible to obtain a complete description of the interfaces, has been lacking. This review article details the authors' efforts to identify the atomic arrangement of light elements such as nitrogen and oxygen at the Si(3)N(4)/SiO(2) interface and in bulk Si(3)N(4) using aberration-corrected scanning transmission electron microscopy.

  20. Phase-contrast imaging in aberration-corrected scanning transmission electron microscopy.

    PubMed

    Krumeich, F; Müller, E; Wepf, R A

    2013-06-01

    Although the presence of phase-contrast information in bright field images recorded with a scanning transmission electron microscope (STEM) has been known for a long time, its systematic exploitation for the structural characterization of materials began only with the availability of aberration-corrected microscopes that allow sufficiently large illumination angles. Today, phase-contrast STEM (PC-STEM) imaging represents an increasingly important alternative to the well-established HRTEM method. In both methods, the image contrast is coherently generated and thus depends not only on illumination and collection angles but on defocus and specimen thickness as well. By PC-STEM, a projection of the crystal potential is obtained in thin areas, with the scattering sites being represented either with dark or bright contrast at two different defocus values which are both close to Gaussian defocus. This imaging behavior can be further investigated by image simulations performed with standard HRTEM simulation software based on the principle of reciprocity. As examples for the application of this method, PC-STEM results obtained on metal nanoparticles and dodecagonal quasicrystals dd-(Ta,V)₁.₆Te are discussed.

  1. Practical spatial resolution of electron energy loss spectroscopy in aberration corrected scanning transmission electron microscopy.

    PubMed

    Shah, A B; Ramasse, Q M; Wen, J G; Bhattacharya, A; Zuo, J M

    2011-08-01

    The resolution of electron energy loss spectroscopy (EELS) is limited by delocalization of inelastic electron scattering rather than probe size in an aberration corrected scanning transmission electron microscope (STEM). In this study, we present an experimental quantification of EELS spatial resolution using chemically modulated 2×(LaMnO(3))/2×(SrTiO(3)) and 2×(SrVO(3))/2×(SrTiO(3)) superlattices by measuring the full width at half maxima (FWHM) of integrated Ti M(2,3), Ti L(2,3), V L(2,3), Mn L(2,3), La N(4,5), La N(2,3) La M(4,5) and Sr L(3) edges over the superlattices. The EELS signals recorded using large collection angles are peaked at atomic columns. The FWHM of the EELS profile, obtained by curve-fitting, reveals a systematic trend with the energy loss for the Ti, V, and Mn edges. However, the experimental FWHM of the Sr and La edges deviates significantly from the observed experimental tendency.

  2. On the optical stability of high-resolution transmission electron microscopes.

    PubMed

    Barthel, J; Thust, A

    2013-11-01

    In the recent two decades the technique of high-resolution transmission electron microscopy experienced an unprecedented progress through the introduction of hardware aberration correctors and by the improvement of the achievable resolution to the sub-Ångström level. The important aspect that aberration correction at a given resolution requires also a well defined amount of optical stability has received little attention so far. Therefore we investigate the qualification of a variety of high-resolution electron microscopes to maintain an aberration corrected optical state in terms of an optical lifetime. We develop a comprehensive statistical framework for the estimation of the optical lifetime and find remarkably low values between tens of seconds and a couple of minutes. Probability curves are introduced, which inform the operator about the chance to work still in the fully aberration corrected state.

  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)

    NASA Astrophysics Data System (ADS)

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

    SciTech Connect

    Lotnyk, Andriy Poppitz, David; Gerlach, Jürgen W.; Rauschenbach, Bernd

    2014-02-17

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

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

    NASA Astrophysics Data System (ADS)

    Lotnyk, Andriy; Poppitz, David; Gerlach, Jürgen W.; Rauschenbach, Bernd

    2014-02-01

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

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

    NASA Astrophysics Data System (ADS)

    Wang, Hongtao; Li, Kun; Cheng, Yingchun; Wang, Qingxiao; Yao, Yingbang; Schwingenschlögl, Udo; Zhang, Xixiang; Yang, Wei

    2012-04-01

    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.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. Electronic supplementary information (ESI) available: Additional Figures for characterization of mono-layer CVD graphene samples with free edges and Pt atoms decorations and analysis of the effect of electron irradiation; supporting movie on edge evolution. See DOI: 10.1039/c2nr00059h

  7. The Stanford Nanocharacterization Laboratory (SNL) and Recent Applications of an Aberration-Corrected Environmental Transmission Electron Microscope**

    PubMed Central

    Sinclair, Robert; Kempen, Paul Joseph; Chin, Richard; Koh, Ai Leen

    2014-01-01

    This article describes the establishment, over a period of ten years or so, of a multi-user, institution-wide facility for the characterization of materials and devices at the nano-scale. Emphasis is placed on the type of equipment that we have found to be most useful for our users, and the business strategy that maintains its operations. A central component of our facility is an aberration-corrected environmental transmission electron microscope and its application is summarized in the studies of plasmon energies of silver nanoparticles, the band gap of PbS quantum dots, atomic site occupancy near grain boundaries in yttria stabilized zirconia, the lithiation of silicon nanoparticles, in situ observations on carbon nanotube oxidation and the electron tomography of varicella zoster virus nucleocapsids. PMID:25364299

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

    SciTech Connect

    Akashi, Tetsuya; Takahashi, Yoshio; Tanigaki, Toshiaki Shimakura, Tomokazu; Kawasaki, Takeshi; Furutsu, Tadao; Shinada, Hiroyuki; Osakabe, Nobuyuki; Müller, Heiko; Haider, Maximilian; Tonomura, Akira

    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.

  9. Controlled polarity of sputter-deposited aluminum nitride on metals observed by aberration corrected scanning transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Harumoto, T.; Sannomiya, T.; Matsukawa, Y.; Muraishi, S.; Shi, J.; Nakamura, Y.; Sawada, H.; Tanaka, T.; Tanishiro, Y.; Takayanagi, K.

    2013-02-01

    The polarity determination process of sputter-deposited aluminum nitride (AlN) on metals has been analyzed using aberration corrected atomic resolution scanning transmission electron microscope. Direct growth of c-axis orientated AlN on face centered cubic metals (fcc) (111) with the local epitaxy has been observed, and the polarity was determined at the AlN/metal interface. We found that the AlN polarity can be controlled by the base metal layer: N-polarity AlN grows on Pt(111) while Al-polarity AlN forms on Al(111). Based on these results, the growth mechanism of AlN on metals is discussed.

  10. Controlled polarity of sputter-deposited aluminum nitride on metals observed by aberration corrected scanning transmission electron microscopy

    SciTech Connect

    Harumoto, T.; Sannomiya, T.; Matsukawa, Y.; Muraishi, S.; Shi, J.; Nakamura, Y.; Sawada, H.; Tanaka, T.; Tanishiro, Y.; Takayanagi, K.

    2013-02-28

    The polarity determination process of sputter-deposited aluminum nitride (AlN) on metals has been analyzed using aberration corrected atomic resolution scanning transmission electron microscope. Direct growth of c-axis orientated AlN on face centered cubic metals (fcc) (111) with the local epitaxy has been observed, and the polarity was determined at the AlN/metal interface. We found that the AlN polarity can be controlled by the base metal layer: N-polarity AlN grows on Pt(111) while Al-polarity AlN forms on Al(111). Based on these results, the growth mechanism of AlN on metals is discussed.

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

    NASA Astrophysics Data System (ADS)

    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).

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

    SciTech Connect

    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 (%3C50nm) 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 "glue" 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

  13. High resolution structural and compositional mapping of the SrTiO3/LaFeO3 interface using chromatic aberration corrected energy filtered imaging

    NASA Astrophysics Data System (ADS)

    Kabius, Bernd; Houben, Lothar; Dwyer, Christian; Colby, Robert; Chambers, Scott A.; Dunin-Borkowski, Rafal

    2014-03-01

    Interfaces between insulating polar perovskites have demonstrated a wealth of electronic and magnetic properties. Understanding and predicting the properties of a specific interface requires atomic level knowledge of interface structure and chemistry. Electron microscopy is capable of this task, and has been frequently applied to oxide interfaces using a combination of high-angle angular dark field scanning transmission electron microscopy (HAADF-STEM) and electron energy-loss spectroscopy (EELS). Energy-filtered TEM (EFTEM) captures a full image for a given energy losses, allowing a larger field of view than typical for STEM-EELS in far less time. However, EFTEM has not, to date, demonstrated the spatial resolution of STEM-EELS due to the limits set by chromatic aberration Cc. This study of LaFeO3/SrTiO3 demonstrates that Cc correction enhances the resolution of EFTEM for elemental mapping, allowing a unit cell-by-unit cell analysis of the concentration gradients across the SrTiO3/LaFeO3 interface. The charge distribution at the interface will be discussed. The research was performed using EMSL, a national scientific user facility sponsored by the Department of Energy's Office of Biological and Environmental Research and located at Pacific Northwest National Laboratory

  14. Three-dimensional locations of gold-labeled proteins in a whole mount eukaryotic cell obtained with 3 nm precision using aberration-corrected scanning transmission electron microscopy

    PubMed Central

    Dukes, Madeline J.; Ramachandra, Ranjan; Baudoin, Jean-Pierre; Jerome, W. Gray; de Jonge, Niels

    2011-01-01

    Three-dimensional (3D) maps of proteins within the context of whole cells are important for investigating cellular function. However, 3D reconstructions of whole cells are challenging to obtain using conventional transmission electron microscopy (TEM). We describe a methodology to determine the 3D locations of proteins labeled with gold nanoparticles on whole eukaryotic cells. The epidermal growth factor receptors on COS7 cells were labeled with gold nanoparticles, and critical-point dried whole-mount cell samples were prepared. 3D focal series were obtained with aberration-corrected scanning transmission electron microscopy (STEM), without tilting the specimen. The axial resolution was improved with deconvolution. The vertical locations of the nanoparticles in a whole-mount cell were determined with a precision of 3 nm. From the analysis of the variation of the axial positions of the labels we concluded that the cellular surface was ruffled. To achieve sufficient stability of the sample under the electron beam irradiation during the recording of the focal series, the sample was carbon coated. A quantitative method was developed to analyze the stability of the ultrastructure after electron beam irradiation using TEM. The results of this study demonstrate the feasibility of using aberration-corrected STEM to study the 3D nanoparticle distribution in whole cells. PMID:21440635

  15. Three-dimensional locations of gold-labeled proteins in a whole mount eukaryotic cell obtained with 3nm precision using aberration-corrected scanning transmission electron microscopy.

    PubMed

    Dukes, Madeline J; Ramachandra, Ranjan; Baudoin, Jean-Pierre; Gray Jerome, W; de Jonge, Niels

    2011-06-01

    Three-dimensional (3D) maps of proteins within the context of whole cells are important for investigating cellular function. However, 3D reconstructions of whole cells are challenging to obtain using conventional transmission electron microscopy (TEM). We describe a methodology to determine the 3D locations of proteins labeled with gold nanoparticles on whole eukaryotic cells. The epidermal growth factor receptors on COS7 cells were labeled with gold nanoparticles, and critical-point dried whole-mount cell samples were prepared. 3D focal series were obtained with aberration-corrected scanning transmission electron microscopy (STEM), without tilting the specimen. The axial resolution was improved with deconvolution. The vertical locations of the nanoparticles in a whole-mount cell were determined with a precision of 3nm. From the analysis of the variation of the axial positions of the labels we concluded that the cellular surface was ruffled. To achieve sufficient stability of the sample under electron beam irradiation during the recording of the focal series, the sample was carbon coated. A quantitative method was developed to analyze the stability of the ultrastructure after electron beam irradiation using TEM. The results of this study demonstrate the feasibility of using aberration-corrected STEM to study the 3D nanoparticle distribution in whole cells.

  16. Aberration corrected emittance exchange

    NASA Astrophysics Data System (ADS)

    Nanni, E. A.; Graves, W. S.

    2015-08-01

    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 multiple orders of magnitude. The transverse emittance is exchanged into the longitudinal dimension using a double dogleg emittance exchange setup with a five 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 an EEX line with emittances differing by four orders of magnitude, i.e., an initial transverse emittance of 1 pm-rad is exchanged with a longitudinal emittance of 10 nm-rad.

  17. Three-dimensional location of a single dopant with atomic precision by aberration-corrected scanning transmission electron microscopy.

    PubMed

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

    2014-01-01

    Materials properties, such as optical and electronic response, can be greatly enhanced by isolated single dopants. Determining the full three-dimensional single-dopant defect structure and spatial distribution is therefore critical to understanding and adequately tuning functional properties. Combining quantitative Z-contrast scanning transmission electron microscopy images with image simulations, we show the direct determination of the atomic-scale depth location of an optically active, single atom Ce dopant embedded within wurtzite-type AlN. The method represents a powerful new tool for reconstructing three-dimensional information from a single, two-dimensional image.

  18. Nanoscale Energy-Filtered Scanning Confocal Electron Microscopy Using a Double-Aberration-Corrected Transmission Electron Microscope

    SciTech Connect

    Wang Peng; Behan, Gavin; Kirkland, Angus I.; Nellist, Peter D.; Takeguchi, Masaki; Hashimoto, Ayako; Mitsuishi, Kazutaka; Shimojo, Masayuki

    2010-05-21

    We demonstrate that a transmission electron microscope fitted with two spherical-aberration correctors can be operated as an energy-filtered scanning confocal electron microscope. A method for establishing this mode is described and initial results showing 3D chemical mapping with nanoscale sensitivity to height and thickness changes in a carbon film are presented. Importantly, uncorrected chromatic aberration does not limit the depth resolution of this technique and moreover performs an energy-filtering role, which is explained in terms of a combined depth and energy-loss response function.

  19. Fine structural features of nanoscale zero-valent iron characterized by spherical aberration corrected scanning transmission electron microscopy (Cs-STEM).

    PubMed

    Liu, Airong; Zhang, Wei-xian

    2014-09-21

    An angstrom-resolution physical model of nanoscale zero-valent iron (nZVI) is generated with a combination of spherical aberration corrected scanning transmission electron microscopy (Cs-STEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDS) and electron energy-loss spectroscopy (EELS) on the Fe L-edge. Bright-field (BF), high-angle annular dark-field (HAADF) and secondary electron (SE) imaging of nZVI acquired by a Hitachi HD-2700 STEM show near atomic resolution images and detailed morphological and structural information of nZVI. The STEM-EDS technique confirms that the fresh nZVI comprises of a metallic iron core encapsulated with a thin layer of iron oxides or oxyhydroxides. SAED patterns of the Fe core suggest the polycrystalline structure in the metallic core and amorphous nature of the oxide layer. Furthermore, Fe L-edge of EELS shows varied structural features from the innermost Fe core to the outer oxide shell. A qualitative analysis of the Fe L(2,3) edge fine structures reveals that the shell of nZVI consists of a mixed Fe(II)/Fe(III) phase close to the Fe (0) interface and a predominantly Fe(III) at the outer surface of nZVI.

  20. Direct atomic-scale imaging of hydrogen and oxygen interstitials in pure niobium using atom-probe tomography and aberration-corrected scanning transmission electron microscopy.

    PubMed

    Kim, Yoon-Jun; Tao, Runzhe; Klie, Robert F; Seidman, David N

    2013-01-22

    Imaging the three-dimensional atomic-scale structure of complex interfaces has been the goal of many recent studies, due to its importance to technologically relevant areas. Combining atom-probe tomography and aberration-corrected scanning transmission electron microscopy (STEM), we present an atomic-scale study of ultrathin (~5 nm) native oxide layers on niobium (Nb) and the formation of ordered niobium hydride phases near the oxide/Nb interface. Nb, an elemental type-II superconductor with the highest critical temperature (T(c) = 9.2 K), is the preferred material for superconducting radio frequency (SRF) cavities in next-generation particle accelerators. Nb exhibits high solubilities for oxygen and hydrogen, especially within the RF-field penetration depth, which is believed to result in SRF quality factor losses. STEM imaging and electron energy-loss spectroscopy followed by ultraviolet laser-assisted local-electrode atom-probe tomography on the same needle-like sample reveals the NbO(2), Nb(2)O(5), NbO, Nb stacking sequence; annular bright-field imaging is used to visualize directly hydrogen atoms in bulk β-NbH.

  1. High-resolution low-dose scanning transmission electron microscopy

    PubMed Central

    Buban, James P.; Ramasse, Quentin; Gipson, Bryant; Browning, Nigel D.; Stahlberg, Henning

    2010-01-01

    During the past two decades instrumentation in scanning transmission electron microscopy (STEM) has pushed toward higher intensity electron probes to increase the signal-to-noise ratio of recorded images. While this is suitable for robust specimens, biological specimens require a much reduced electron dose for high-resolution imaging. We describe here protocols for low-dose STEM image recording with a conventional field-emission gun STEM, while maintaining the high-resolution capability of the instrument. Our findings show that a combination of reduced pixel dwell time and reduced gun current can achieve radiation doses comparable to low-dose TEM. PMID:19915208

  2. High-resolution low-dose scanning transmission electron microscopy.

    PubMed

    Buban, James P; Ramasse, Quentin; Gipson, Bryant; Browning, Nigel D; Stahlberg, Henning

    2010-01-01

    During the past two decades instrumentation in scanning transmission electron microscopy (STEM) has pushed toward higher intensity electron probes to increase the signal-to-noise ratio of recorded images. While this is suitable for robust specimens, biological specimens require a much reduced electron dose for high-resolution imaging. We describe here protocols for low-dose STEM image recording with a conventional field-emission gun STEM, while maintaining the high-resolution capability of the instrument. Our findings show that a combination of reduced pixel dwell time and reduced gun current can achieve radiation doses comparable to low-dose TEM.

  3. Inorganic WS2 nanotubes revealed atom by atom using ultra-high-resolution transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Bar Sadan, Maya; Heidelmann, Markus; Houben, Lothar; Tenne, Reshef

    2009-08-01

    The characterization of nanostructures to the atomic dimensions becomes more important, as devices based on a single particle are being produced. In particular, inorganic nanotubes were shown to host interesting properties making them excellent candidates for various devices. The WS2 nanotubes outperform the bulk in their mechanical properties offering numerous applications especially as part of high strength nanocomposites. In contrast, their electrical properties are less remarkable. The structure-function relationship can be investigated by aberration-corrected high-resolution transmission electron microscopy (HRTEM), which enables the insight into their atomic structure as well as performing spectroscopic measurements down to the atomic scale. In the present work, the deciphering of atomic structure and the chiral angle of the different shells in a multiwall WS2 nanotube is demonstrated. In certain cases, the helicity of the structure can also be deduced. Finally, first electron energy loss spectra (EELS) of a single tube are presented, acquired by a new acquisition technique that allows for high spatial resolution (denoted StripeSTEM). The measured band gap values correspond with the values found in literature for thin films, obtained by spectroscopic techniques, and are higher than the values resulting from STM measurements.

  4. High-Resolution Transmission Electron Microscopy Using Negative Spherical Aberration

    NASA Astrophysics Data System (ADS)

    Jia, Chun-Lin; Lentzen, Markus

    2004-04-01

    A novel imaging mode for high-resolution transmission electron microscopy is described. It is based on the adjustment of a negative value of the spherical aberration CS of the objective lens of a transmission electron microscope equipped with a multipole aberration corrector system. Negative spherical aberration applied together with an overfocus yields high-resolution images with bright-atom contrast. Compared to all kinds of images taken in conventional transmission electron microscopes, where the then unavoidable positive spherical aberration is combined with an underfocus, the contrast is dramatically increased. This effect can only be understood on the basis of a full nonlinear imaging theory. Calculations show that the nonlinear contrast contributions diminish the image contrast relative to the linear image for a positive-CS setting whereas they reinforce the image contrast relative to the linear image for a negative-CS setting. The application of the new mode to the imaging of oxygen in SrTiO3 and YBa2Cu3O7 demonstrates the benefit to materials science investigations. It allows us to image directly, without further image processing, strongly scattering heavy-atom columns together with weakly scattering light-atom columns.

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

    NASA Astrophysics Data System (ADS)

    Pennycook, S. J.; Jesson, D. E.

    1992-03-01

    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.

  6. High Resolution Transmission Electron Microscopy (HRTEM) of nanophase ferric oxides

    NASA Technical Reports Server (NTRS)

    Golden, D. C.; Morris, R. V.; Ming, D. W.; Lauer, H. V., Jr.

    1994-01-01

    Iron oxide minerals are the prime candidates for Fe(III) signatures in remotely sensed Martian surface spectra. Magnetic, Mossbauer, and reflectance spectroscopy have been carried out in the laboratory in order to understand the mineralogical nature of Martian analog ferric oxide minerals of submicron or nanometer size range. Out of the iron oxide minerals studied, nanometer sized ferric oxides are promising candidates for possible Martian spectral analogs. 'Nanophase ferric oxide (np-Ox)' is a generic term for ferric oxide/oxihydroxide particles having nanoscale (less than 10 nm) particle dimensions. Ferrihydrite, superparamagnetic particles of hematite, maghemite and goethite, and nanometer sized particles of inherently paramagnetic lepidocrocite are all examples of nanophase ferric oxides. np-Ox particles in general do not give X-ray diffraction (XRD) patterns with well defined peaks and would often be classified as X-ray amorphous. Therefore, different np-Oxs preparations should be characterized using a more sensitive technique e.g., high resolution transmission electron microscopy (HRTEM). The purpose of this study is to report the particle size, morphology and crystalline order, of five np-Ox samples by HRTEM imaging and electron diffraction (ED).

  7. High resolution analytical transmission electron microscopy of magnetic recording media

    NASA Astrophysics Data System (ADS)

    Risner, Juliet Danielle

    Since the invention of the hard disk drive in 1954, the density of bits per disk has increased exponentially. This trend is partly due to improvements to the magnetic recording media. In current hard disks, each bit is approximately 0.04 mum in its smallest dimension and comprises ˜100 hexagonal close packed Co-alloy magnetic grains. These grains have magnetic "easy" axes oriented longitudinally, or parallel to the film plane. Future recording media have easy axes oriented perpendicular to the film plane. Perpendicular media are expected to provide continued increases in storage density above the limit of longitudinal media. Quantum-mechanical exchange coupling between magnetic grains degrades the signal-to-noise ratio (SNR) and limits storage density in both media types. Controlling exchange coupling is possible by creating nonmagnetic grain boundaries which compositionally isolate the magnetic grains. High-resolution analytical transmission electron microscopy (TEM) is required to study these media because of their nano-scale grains and grain boundaries. Examining the microstructure and elemental distribution in these films at near atomic level is paramount to understanding their magnetic performance. The microstructure and elemental distribution in longitudinal and perpendicular media were examined using high resolution analytical TEM techniques, such as energy-filtered TEM (EFTEM), energy-dispersive x-ray spectroscopy (EDS) using a 1.5 nm electron probe, and spectrum imaging with a scanning TEM. These techniques successfully determined how grain boundary Cr segregation varies with grain orientation in longitudinal media. Boundaries misoriented by 0° and 90° commonly occur and were found to have minimal Cr segregation, which limits storage density improvement in these media. Analytical TEM techniques applied to oxygen-enriched perpendicular media, fabricated using different deposition methods, effectively related microstructure and composition to magnetic

  8. High resolution transmission electron microscope Imaging and first-principles simulations of atomic-scale features in graphene membrane

    NASA Astrophysics Data System (ADS)

    Wang, Wei; Bhandari, Sagar; Yi, Wei; Bell, David; Westervelt, Robert; Kaxiras, Efthimios

    2012-02-01

    Ultra-thin membranes such as graphene[1] are of great importance for basic science and technology applications. Graphene sets the ultimate limit of thinness, demonstrating that a free-standing single atomic layer not only exists but can be extremely stable and strong [2--4]. However, both theory [5, 6] and experiments [3, 7] suggest that the existence of graphene relies on intrinsic ripples that suppress the long-wavelength thermal fluctuations which otherwise spontaneously destroy long range order in a two dimensional system. Here we show direct imaging of the atomic features in graphene including the ripples resolved using monochromatic aberration-corrected transmission electron microscopy (TEM). We compare the images observed in TEM with simulated images based on an accurate first-principles total potential. We show that these atomic scale features can be mapped through accurate first-principles simulations into high resolution TEM contrast. [1] Geim, A. K. & Novoselov, K. S. Nat. Mater. 6, 183-191, (2007). [2] Novoselov, K. S.et al. Science 306, 666-669, (2004). [3] Meyer, J. C. et al. Nature 446, 60-63, (2007). [4] Lee, C., Wei, X. D., Kysar, J. W. & Hone, J. Science 321, 385-388, (2008). [5] Nelson, D. R. & Peliti, L. J Phys-Paris 48, 1085-1092, (1987). [6] Fasolino, A., Los, J. H. & Katsnelson, M. I. Nat. Mater. 6, 858-861, (2007). [7] Meyer, J. C. et al. Solid State Commun. 143, 101-109, (2007).

  9. Extended Depth of Field for High-Resolution Scanning Transmission Electron Microscopy

    SciTech Connect

    Hovden, Robert; Xin, Huolin L.; Muller, David A.

    2010-12-02

    Aberration-corrected scanning transmission electron microscopes (STEMs) provide sub-Angstrom lateral resolution; however, the large convergence angle greatly reduces the depth of field. For microscopes with a small depth of field, information outside of the focal plane quickly becomes blurred and less defined. It may not be possible to image some samples entirely in focus. Extended depth-of-field techniques, however, allow a single image, with all areas in focus, to be extracted from a series of images focused at a range of depths. In recent years, a variety of algorithmic approaches have been employed for bright-field optical microscopy. Here, we demonstrate that some established optical microscopy methods can also be applied to extend the ~6 nm depth of focus of a 100 kV 5th-order aberration-corrected STEM (α{sub max} = 33 mrad) to image Pt-Co nanoparticles on a thick vulcanized carbon support. These techniques allow us to automatically obtain a single image with all the particles in focus as well as a complimentary topography map.

  10. Optical advantages of astigmatic aberration corrected heliostats

    NASA Astrophysics Data System (ADS)

    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.

  11. Pulse compressor with aberration correction

    SciTech Connect

    Mankos, Marian

    2015-11-30

    In this SBIR project, Electron Optica, Inc. (EOI) is developing an electron mirror-based pulse compressor attachment to new and retrofitted dynamic transmission electron microscopes (DTEMs) and ultrafast electron diffraction (UED) cameras for improving the temporal resolution of these instruments from the characteristic range of a few picoseconds to a few nanoseconds and beyond, into the sub-100 femtosecond range. The improvement will enable electron microscopes and diffraction cameras to better resolve the dynamics of reactions in the areas of solid state physics, chemistry, and biology. EOI’s pulse compressor technology utilizes the combination of electron mirror optics and a magnetic beam separator to compress the electron pulse. The design exploits the symmetry inherent in reversing the electron trajectory in the mirror in order to compress the temporally broadened beam. This system also simultaneously corrects the chromatic and spherical aberration of the objective lens for improved spatial resolution. This correction will be found valuable as the source size is reduced with laser-triggered point source emitters. With such emitters, it might be possible to significantly reduce the illuminated area and carry out ultrafast diffraction experiments from small regions of the sample, e.g. from individual grains or nanoparticles. During phase I, EOI drafted a set of candidate pulse compressor architectures and evaluated the trade-offs between temporal resolution and electron bunch size to achieve the optimum design for two particular applications with market potential: increasing the temporal and spatial resolution of UEDs, and increasing the temporal and spatial resolution of DTEMs. Specialized software packages that have been developed by MEBS, Ltd. were used to calculate the electron optical properties of the key pulse compressor components: namely, the magnetic prism, the electron mirror, and the electron lenses. In the final step, these results were folded

  12. High resolution transmission spectroscopy as a diagnostic for Jovian exoplanet atmospheres: constraints from theoretical models

    SciTech Connect

    Kempton, Eliza M.-R.; Perna, Rosalba; Heng, Kevin

    2014-11-01

    We present high resolution transmission spectra of giant planet atmospheres from a coupled three-dimensional (3D) atmospheric dynamics and transmission spectrum model that includes Doppler shifts which arise from winds and planetary motion. We model Jovian planets covering more than two orders of magnitude in incident flux, corresponding to planets with 0.9-55 day orbital periods around solar-type stars. The results of our 3D dynamical models reveal certain aspects of high resolution transmission spectra that are not present in simple one-dimensional (1D) models. We find that the hottest planets experience strong substellar to anti-stellar (SSAS) winds, resulting in transmission spectra with net blueshifts of up to 3 km s{sup –1}, whereas less irradiated planets show almost no net Doppler shifts. We find only minor differences between transmission spectra for atmospheres with temperature inversions and those without. Compared to 1D models, peak line strengths are significantly reduced for the hottest atmospheres owing to Doppler broadening from a combination of rotation (which is faster for close-in planets under the assumption of tidal locking) and atmospheric winds. Finally, high resolution transmission spectra may be useful in studying the atmospheres of exoplanets with optically thick clouds since line cores for very strong transitions should remain optically thick to very high altitude. High resolution transmission spectra are an excellent observational test for the validity of 3D atmospheric dynamics models, because they provide a direct probe of wind structures and heat circulation. Ground-based exoplanet spectroscopy is currently on the verge of being able to verify some of our modeling predictions, most notably the dependence of SSAS winds on insolation. We caution that interpretation of high resolution transmission spectra based on 1D atmospheric models may be inadequate, as 3D atmospheric motions can produce a noticeable effect on the absorption

  13. Probing structures of nanomaterials using advanced electron microscopy methods, including aberration-corrected electron microscopy at the Angstrom scale.

    PubMed

    Gai, Pratibha L; Yoshida, Kenta; Shute, Carla; Jia, Xiaoting; Walsh, Michael; Ward, Michael; Dresselhaus, Mildred S; Weertman, Julia R; Boyes, Edward D

    2011-07-01

    Structural and compositional studies of nanomaterials of technological importance have been carried out using advanced electron microscopy methods, including aberration-corrected transmission electron microscopy (AC-TEM), AC-high angle annular dark field scanning TEM (AC-HAADF-STEM), AC-energy filtered TEM, electron-stimulated energy dispersive spectroscopy in the AC-(S)TEM and high-resolution TEM (HRTEM) with scanning tunneling microscopy (STM) holder. The AC-EM data reveal improvements in resolution and minimization in image delocalization. A JEOL 2200FS double-AC field emission gun TEM/STEM operating at 200 kV in the Nanocentre at the University of York has been used to image single metal atoms on crystalline supports in catalysts, grain boundaries in nanotwinned metals, and nanostructures of tetrapods. Joule heating studies using HRTEM integrated with an STM holder reveal in situ crystallization and edge reconstruction in graphene. Real-time in situ AC-HAADF-STEM studies at elevated temperatures are described. Dynamic in-column energy filtering in an AC environment provides an integral new approach to perform dynamic in situ studies with aberration correction. The new results presented here open up striking new opportunities for atomic scale studies of nanomaterials and indicate future development directions.

  14. Atomic-scale observation of migration and coalescence of Au nanoclusters on YSZ surface by aberration-corrected STEM.

    PubMed

    Li, Junjie; Wang, Zhongchang; Chen, Chunlin; Huang, Sumei

    2014-07-01

    Unraveling structural dynamics of noble metal nanoclusters on oxide supports is critical to understanding reaction process and origin of catalytic activity in heterogeneous catalysts. Here, we show that aberration-corrected scanning transmission electron microscopy can provide direct atomic-resolution imaging of surface migration, coalescence, and atomic rearrangement of Au clusters on an Y:ZrO₂ (YSZ) support. The high resolution enables us to reveal migration and coalescence process of Au clusters at the atomic scale, and to demonstrate that the coalesced clusters undergo a cooperative atomic rearrangement, which transforms the coherent into incoherent Au/YSZ interface. This approach can help to elucidate atomistic mechanism of catalytic activities and to develop novel catalysts with enhanced functionality.

  15. In-situ high resolution transmission electron microscopy observation of silicon nanocrystal nucleation in a SiO{sub 2} bilayered matrix

    SciTech Connect

    Yang, T. C.-J. Wu, L.; Lin, Z.; Jia, X.; Puthen-Veettil, B.; Zhang, T.; Conibeer, G.; Perez-Wurfl, I.; Kauffmann, Y.; Rothschild, A.

    2014-08-04

    Solid-state nucleation of Si nanocrystals in a SiO{sub 2} 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 SiO{sub 2} bilayered matrix fabricated through radio frequency co-sputtering. The results show that the shapes of Si nanocrystals in amorphous SiO{sub 2} 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 SiO{sub 2}. This study demonstrates the potential of in-situ HRTEM as a tool to observe the real time nucleation of Si nanocrystals in a SiO{sub 2} bilayered matrix. Furthermore, ideas for improvements on this in-situ heating HRTEM technique are discussed.

  16. Conformal dome aberration correction by designing the inner surface

    NASA Astrophysics Data System (ADS)

    Zhang, Wang; Chen, Shouqian; Fan, Zhigang

    2016-12-01

    The ray transmission models of optical domes were established, and the characteristics of the rays while passing through a hemispherical dome and a conformal dome were comparatively analysed. Acquiring the minimum deviated angles from the inner surface of the conformal dome was then determined to be the designing goal for reducing the dynamic aberrations. Based on this, the inner surface of the conformal dome was optimized and thus, the dynamic aberrations were reduced. Finally, a completely cooled conformal optical system was designed. The results show that the optical system have produced good imaging quality within all the fields of regard, which further illustrates that designing the inner surface of a conformal dome is an effective method for aberration correction.

  17. Contamination-free transmission electron microscopy for high-resolution carbon elemental mapping of polymers.

    PubMed

    Horiuchi, Shin; Hanada, Takeshi; Ebisawa, Masaharu; Matsuda, Yasuhiro; Kobayashi, Motoyasu; Takahara, Atsushi

    2009-05-26

    Specimen contamination induced by electron beam irradiation has long been a serious problem for high-resolution imaging and analysis by a transmission electron microscope (TEM). It creates a deposition of carbonaceous compounds on a region under study, causing the loss of resolution. We developed a method to reduce the beam-induced specimen contamination by cleaning a TEM with activated oxygen radicals. The hydrocarbon contaminants accumulated inside the microscope's chamber can be etched away by gentle chemical oxidation without causing any damage to the microscope. The "contamination-free TEM" can effectively suppress the deposition of carbon-rich products on a specimen and therefore enables us to perform high-resolution carbon elemental mapping by energy-filtering transmission electron microscopy (EFTEM). In this study, we investigated the structure of polymer brushes immobilized on a silica nanoparticle (SiNP), of which molecular weight, length, and density of the brushes had been characterized in detail. The isolated particle showed the stretched formations of the polymer chains growing from the surface, while the densely distributed particles showed the connection of the polymer chains between neighboring particles. Moreover, the polymer brush layer and the surface initiator could be differentiated from each other by the component-specific contrast achieved by electron spectroscopic imaging (ESI). The contamination-free TEM can allow us to perform high-resolution carbon mapping and is expected to provide deep insights of soft materials' nanostructures. PMID:19402650

  18. Soot Nanostructure: Using Fringe Analysis Software on High Resolution Transmission Electron Microscopy of Carbon Soot

    NASA Technical Reports Server (NTRS)

    King, James D.

    2004-01-01

    Using high resolution transmission electron images of carbon nanotubes and carbon particles, we are able to use image analysis program to determine several carbon fringe properties, including length, separation, curvature and orientation. Results are shown in the form of histograms for each of those quantities. The combination of those measurements can give a better indication of the graphic structure within nanotubes and particles of carbon and can distinguish carbons based upon fringe properties. Carbon with longer, straighter and closer spaced fringes are considered graphite, while amorphous carbon contain shorter, less structured fringes.

  19. High Resolution Separations and Improved Ion Production and Transmission in Metabolomics

    SciTech Connect

    Metz, Thomas O.; Page, Jason S.; Baker, Erin Shammel; Tang, Keqi; Ding, Jie; Shen, Yufeng; Smith, Richard D.

    2008-03-31

    The goal of metabolomics experiments is the detection and quantitation of as many sample components as reasonably possible in order to identify “features” that can be used to characterize the samples under study. When utilizing electrospray ionization to produce ions for analysis by mass spectrometry (MS), it is imperative that metabolome sample constituents be efficiently separated prior to ion production, in order to minimize the phenomenon of ionization suppression. Similarly, optimization of the MS inlet can lead to increased measurement sensitivity. This review will focus on the role of high resolution liquid chromatography (LC) separations in conjunction with improved ion production and transmission for LC-MS-based metabolomics.

  20. Nanocrystal Phase Identification by Lattice Fringe Fingerprinting from High Resolution Transmission Electron Microscope Images

    NASA Astrophysics Data System (ADS)

    Bjorge, Ruben; Seipel, Bjoern; Moeck, Peter; Fraundorf, Philip

    2006-05-01

    Lattice fringe fingerprinting is a novel and powerful method of identifying and characterizing nanocrystalline structures or materials based on images from direct space high-resolution transmission electron microscopy (HRTEM). We examine Fourier transformed HRTEM images of nanocrystals in certain orientations (i.e. lattice fringes and cross fringes) in order to obtain a lattice fringe fingerprint plot. Such plots are used to identify a crystalline nanoparticle by comparing the experimental data with data that are derived from a comprehensive database. A lattice fringe fingerprint plot is similar to a classical X-ray powder diffractogram, but an important advantage is that the intersection angles of lattice fringes give us additional information. When transmission electron microscope image acquisition and data interpretation are automated and connected to a comprehensive database (such as our Nano-Crystallography Database, http://nanocrystallography.research.pdx.edu/), fringe fingerprinting will be able to compete with powder X-ray diffraction in identifying unknown nanocrystals on a routine basis.

  1. Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

    DOE PAGES

    Wang, Xueju; Pan, Zhipeng; Fan, Feifei; Wang, Jiangwei; Liu, Yang; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-09-10

    We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for themore » analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.« less

  2. Nanoscale deformation analysis with high-resolution transmission electron microscopy and digital image correlation

    SciTech Connect

    Wang, Xueju; Pan, Zhipeng; Fan, Feifei; Wang, Jiangwei; Liu, Yang; Mao, Scott X.; Zhu, Ting; Xia, Shuman

    2015-09-10

    We present an application of the digital image correlation (DIC) method to high-resolution transmission electron microscopy (HRTEM) images for nanoscale deformation analysis. The combination of DIC and HRTEM offers both the ultrahigh spatial resolution and high displacement detection sensitivity that are not possible with other microscope-based DIC techniques. We demonstrate the accuracy and utility of the HRTEM-DIC technique through displacement and strain analysis on amorphous silicon. Two types of error sources resulting from the transmission electron microscopy (TEM) image noise and electromagnetic-lens distortions are quantitatively investigated via rigid-body translation experiments. The local and global DIC approaches are applied for the analysis of diffusion- and reaction-induced deformation fields in electrochemically lithiated amorphous silicon. As a result, the DIC technique coupled with HRTEM provides a new avenue for the deformation analysis of materials at the nanometer length scales.

  3. Limited Area Coverage/High Resolution Picture Transmission (LAC/HRPT) data vegetative index calculation processor user's manual

    NASA Technical Reports Server (NTRS)

    Obrien, S. O. (Principal Investigator)

    1980-01-01

    The program, LACVIN, calculates vegetative indexes numbers on limited area coverage/high resolution picture transmission data for selected IJ grid sections. The IJ grid sections were previously extracted from the full resolution data tapes and stored on disk files.

  4. Numerical spherical aberration correction method using spatial light modulator under deep-part fluorescence observation

    NASA Astrophysics Data System (ADS)

    Takiguchi, Yu; Takamoto, Hisayoshi; Kanada, Masamitsu; Inoue, Takashi; Matsumoto, Naoya; Terakawa, Susumu

    2014-03-01

    We have developed a confocal fluorescence laser scanning microscopy (CFLSM) incorporating a liquid crystal on silicon spatial light modulator (LCOS-SLM). To achieve high-resolution and high-contrast imaging for deeper part of the tissue with CFLSM, high numerical aperture objective lenses are required to tightly focus excitation light to meet Rayleigh limit(criterion) for the specimens. However, mismatch of refractive index at the boundary of interfacing materials, such as atmosphere, glass cover, and biological tissues, causes spherical aberration. Recently, we proposed a numerical method for correcting spherical aberration. In this method a pre-distorted wavefront pattern for aberration correction is calculated by ray tracing from a hypothetical focal point inside a specimen to the pupil plane. The resulting microscope can correct such spherical aberration. We observed 6.0μm fluorescent micro-beads dispersed three-dimensionally in agarose gel to confirm effectiveness of aberration correction. We reconstructed a three-dimensional image by taking 20 images by changing the depth with 1 μm interval and stacking them. It was apparent that the longitudinal/depth resolution was improved and that the intensity of fluorescence image was increased with aberration correction. While this method is applicable to other laser scanning microscopes, it has potential to enhance the signals for various super-resolution microscopic techniques, such as stimulated- emission-depletion (STED) fluorescence microscopy.

  5. Molecular interactions on single-walled carbon nanotubes revealed by high-resolution transmission microscopy

    NASA Astrophysics Data System (ADS)

    Umeyama, Tomokazu; Baek, Jinseok; Sato, Yuta; Suenaga, Kazu; Abou-Chahine, Fawzi; Tkachenko, Nikolai V.; Lemmetyinen, Helge; Imahori, Hiroshi

    2015-07-01

    The close solid-state structure-property relationships of organic π-aromatic molecules have attracted interest due to their implications for the design of organic functional materials. In particular, a dimeric structure, that is, a unit consisting of two molecules, is required for precisely evaluating intermolecular interactions. Here, we show that the sidewall of a single-walled carbon nanotube (SWNT) represents a unique molecular dimer platform that can be directly visualized using high-resolution transmission electron microscopy. Pyrene is chosen as the π-aromatic molecule; its dimer is covalently linked to the SWNT sidewalls by aryl addition. Reflecting the orientation and separation of the two molecules, the pyrene dimer on the SWNT exhibits characteristic optical and photophysical properties. The methodology discussed here--form and probe molecular dimers--is highly promising for the creation of unique models and provides indispensable and fundamental information regarding molecular interactions.

  6. Molecular interactions on single-walled carbon nanotubes revealed by high-resolution transmission microscopy

    PubMed Central

    Umeyama, Tomokazu; Baek, Jinseok; Sato, Yuta; Suenaga, Kazu; Abou-Chahine, Fawzi; Tkachenko, Nikolai V.; Lemmetyinen, Helge; Imahori, Hiroshi

    2015-01-01

    The close solid-state structure–property relationships of organic π−aromatic molecules have attracted interest due to their implications for the design of organic functional materials. In particular, a dimeric structure, that is, a unit consisting of two molecules, is required for precisely evaluating intermolecular interactions. Here, we show that the sidewall of a single-walled carbon nanotube (SWNT) represents a unique molecular dimer platform that can be directly visualized using high-resolution transmission electron microscopy. Pyrene is chosen as the π−aromatic molecule; its dimer is covalently linked to the SWNT sidewalls by aryl addition. Reflecting the orientation and separation of the two molecules, the pyrene dimer on the SWNT exhibits characteristic optical and photophysical properties. The methodology discussed here—form and probe molecular dimers—is highly promising for the creation of unique models and provides indispensable and fundamental information regarding molecular interactions. PMID:26173983

  7. High resolution transmission electron microscopic in-situ observations of plastic deformation of compressed nanocrystalline gold

    SciTech Connect

    Wang, Guoyong; Lian, Jianshe; Jiang, Qing; Sun, Sheng; Zhang, Tong-Yi

    2014-09-14

    Nanocrystalline (nc) metals possess extremely high strength, while their capability to deform plastically has been debated for decades. Low ductility has hitherto been considered an intrinsic behavior for most nc metals, due to the lack of five independent slip systems actively operating during deformation in each nanograin. Here we report in situ high resolution transmission electron microscopic (HRTEM) observations of deformation process of nc gold under compression, showing the excellent ductility of individual and aggregate nanograins. Compression causes permanent change in the profile of individual nanograins, which is mediated by dislocation slip and grain rotation. The high rate of grain boundary sliding and large extent of widely exited grain rotation may meet the boundary compatibility requirements during plastic deformation. The in situ HRTEM observations suggest that nc gold is not intrinsically brittle under compressive loading.

  8. Nano features of Al/Au ultrasonic bond interface observed by high resolution transmission electron microscopy

    SciTech Connect

    Ji Hongjun; Li Mingyu Kim, Jong-Myung; Kim, Dae-Won; Wang Chunqing

    2008-10-15

    Nano-scale interfacial details of ultrasonic AlSi1 wire wedge bonding to a Au/Ni/Cu pad were investigated using high resolution transmission electron microscopy (HRTEM). The intermetallic phase Au{sub 8}Al{sub 3} formed locally due to diffusion and reaction activated by ultrasound at the Al/Au bond interface. Multilayer sub-interfaces roughly parallel to the wire/pad interface were observed among this phase, and interdiffusional features near the Au pad resembled interference patterns, alternately dark and bright bars. Solid-state diffusion theory cannot be used to explain why such a thick compound formed within milliseconds at room temperature. The major formation of metallurgical bonds was attributed to ultrasonic cyclic vibration.

  9. Aberration-corrected STEM for atomic-resolution imaging and analysis.

    PubMed

    Krivanek, O L; Lovejoy, T C; Dellby, N

    2015-09-01

    Aberration-corrected scanning transmission electron microscopes are able to form electron beams smaller than 100 pm, which is about half the size of an average atom. Probing materials with such beams leads to atomic-resolution images, electron energy loss and energy-dispersive X-ray spectra obtained from single atomic columns and even single atoms, and atomic-resolution elemental maps. We review briefly how such electron beams came about, and show examples of applications. We also summarize recent developments that are propelling aberration-corrected scanning transmission electron microscopes in new directions, such as complete control of geometric aberration up to fifth order, and ultra-high-energy resolution EELS that is allowing vibrational spectroscopy to be carried out in the electron microscope.

  10. Computer Simulation of High Resolution Transmission Electron Micrographs: Theory and Analysis.

    NASA Astrophysics Data System (ADS)

    Kilaas, Roar

    Computer simulation of electron micrographs is an invaluable aid in their proper interpretation and in defining optimum conditions for obtaining images experimentally. Since modern instruments are capable of atomic resolution, simulation techniques employing high precision are required. This thesis makes contributions to four specific areas of this field. First, the validity of a new method for simulating high resolution electron microscope images has been critically examined. This method, which has been termed the real space method (RSP) since the entire calculation is performed without any Fourier transforms, offers a considerable reduction in computing time over the conventional multislice approach when identical sampling conditions are employed. However, for the same level of accuracy the real space method requires more sampling points and more computing time than the conventional multislice method. These characteristics are illustrated with calculated results using both methods to identify practical limitations. Second, three different methods for computing scattering amplitudes in High Resolution Transmission Electron Microscopy (HRTEM) have been investigated as to their ability to include upper Laue layer (ULL) interaction. The conventional first order multislice method using fast Fourier transform (FFT) and the second order multislice (SOM) method are shown to yield calculated intensities of first order Laue reflections with the use of slice thicknesses smaller than the crystal periodicity along the incident electron beam direction. It is argued that the calculated intensities of ULL reflections approach the correct values in the limiting case of vanishing slice thickness and electron wavelength. The third method, the improved phasegrating method (IPG) does also in principle include ULL effects, but is severely limited as to choice of slice thickness and sampling interval. A practical way to use slice thicknesses less than the crystal periodicity along the

  11. Behavior of Au species in Au/Fe2O3 catalysts characterized by novel in situ heating techniques and aberration-corrected STEM imaging.

    PubMed

    Allard, Lawrence F; Flytzani-Stephanopoulos, Maria; Overbury, Steven H

    2010-08-01

    The recent advent of a novel design of in situ heating technology for electron microscopes has permitted unprecedented control of elevated temperature studies of catalytic materials, particularly when coupled with the sub-Angström imaging performance of a modern aberration-corrected scanning transmission electron microscope (STEM). Using micro-electro-mechanical-systems (MEMS)-based Aduro heating chips from Protochips, Inc. (Raleigh, NC, USA) allows nearly instantaneous heating and cooling of catalyst powders, avoiding effects of temperature ramping as experienced with standard heating stages. The heating technology also provides stable operation limited only by the inherent drift in the microscope stage, thus allowing full image resolution to be achieved even at elevated temperatures. The present study details the use of both the high X-Y spatial resolution in both dark-field and simultaneous bright-field imaging, along with the high resolution in Z (depth sectioning) provided by the large probe incidence semiangle in the aberration-corrected instrument, to characterize the evolution of microstructure in a commercial Au/Fe2O3 water-gas shift catalyst during elevated temperature treatment. The phenomenon of Au diffusion to the surface of hematite support particles to form discrete crystalline Au nanoparticles in the 1-2 nm size range, after a prior leaching treatment to remove surface Au species has been characterized.

  12. Transient Thermometry and High-Resolution Transmission Electron Microscopy Analysis of Filamentary Resistive Switches.

    PubMed

    Kwon, Jonghan; Sharma, Abhishek A; Chen, Chao-Yang; Fantini, Andrea; Jurczak, Malgorzata; Herzing, Andrew A; Bain, James A; Picard, Yoosuf N; Skowronski, Marek

    2016-08-10

    We present data on the filament size and temperature distribution in Hf0.82Al0.18Ox-based Resistive Random Access Memory (RRAM) devices obtained by transient thermometry and high-resolution transmission electron microscopy (HRTEM). The thermometry shows that the temperature of the nonvolatile conducting filament can reach temperatures as high as 1600 K at the onset of RESET at voltage of 0.8 V and power of 40 μW. The size of the filament was estimated at about 1 nm in diameter. Hot filament increases the temperature of the surrounding high resistivity oxide, causing it to conduct and carry a significant fraction of the total current. The current spreading results in slowing down the filament temperature increase at higher power. The results of thermometry have been corroborated by HRTEM analysis of the as-fabricated and switched RRAM devices. The functional HfAlOx layer in as-fabricated devices is amorphous. In devices that were switched, we detected a small crystalline region of 10-15 nm in size. The crystallization temperature of the HfAlOx was determined to be 850 K in an independent annealing experiment. The size of the crystalline region agrees with thermal modeling based on the thermometry data. Scanning transmission electron microscopy (TEM) coordinated with electron energy loss spectroscopy could not detect changes in the chemical makeup of the filament. PMID:27351065

  13. High resolution Transmission Electron Microscopy characterization of a milled oxide dispersion strengthened steel powder

    NASA Astrophysics Data System (ADS)

    Loyer-Prost, M.; Merot, J.-S.; Ribis, J.; Le Bouar, Y.; Chaffron, L.; Legendre, F.

    2016-10-01

    Oxide Dispersion Strengthened (ODS) steels are promising materials for generation IV fuel claddings as their dense nano-oxide dispersion provides good creep and irradiation resistance. Even if they have been studied for years, the formation mechanism of these nano-oxides is still unclear. Here we report for the first time a High Resolution Transmission Electron Microscopy and Energy Filtered Transmission Electron Microscopy characterization of an ODS milled powder. It provides clear evidence of the presence of small crystalline nanoclusters (NCs) enriched in titanium directly after milling. Small NCs (<5 nm) have a crystalline structure and seem partly coherent with the matrix. They have an interplanar spacing close to the (011) bcc iron structure. They coexist with larger crystalline spherical precipitates of 15-20 nm in size. Their crystalline structure may be metastable as they are not consistent with any Y-Ti-O or Ti-O structure. Such detailed observations in the as-milled grain powder confirm a mechanism of Y, Ti, O dissolution in the ferritic matrix followed by a NC precipitation during the mechanical alloying process of ODS materials.

  14. In-Situ High-Resolution Transmission Electron Microscopy Investigation of Overheating of Cu Nanoparticles

    PubMed Central

    Chen, Chunlin; Hu, Ziyu; Li, Yanfen; Liu, Limin; Mori, Hirotaro; Wang, Zhangchang

    2016-01-01

    Synthesizing and functionalizing metal nanoparticles supported on substrates is currently the subject of intensive study owing to their outstanding catalytic performances for heterogeneous catalysis. Revealing the fundamental effect of the substrates on metal nanoparticles represents a key step in clarifying mechanisms of stability and catalytic properties of these heterogeneous systems. However, direct identification of these effects still poses a significant challenge due to the complicacy of interactions between substrates and nanoparticles and also for the technical difficulty, restraining our understanding of these heterogeneous systems. Here, we combine in situ high-resolution transmission electron microscopy with molecular dynamics simulations to investigate Cu nanoparticles supported on graphite and Cu2O substrates, and demonstrate that melting behavior and thermal stability of Cu nanoparticles can be markedly influenced by substrates. The graphite-supported Cu nanoparticles do not melt during annealing at 1073 K until they vanish completely, i.e. only the sublimation occurs, while the Cu2O-supported Cu nanoparticles suffer melting during annealing at 973 K. Such selective superheating of the Cu nanoparticles can be attributed to the adsorption of a thin carbon layer on the surface of the Cu nanoparticles, which helps guide further stability enhancement of functional nanoparticles for realistic applications. PMID:26785839

  15. High resolution transmission electron microscopy of melamine-formaldehyde aerogels and silica aerogels

    SciTech Connect

    Ruben, G.C. . Dept. of Biological Sciences)

    1991-09-01

    The goal of the high resolution transmission electron microscopy (HRTEM) was to image the structure of two tetramethyl orthosilicate (TMOS) and two melamine-formaldehyde (MF) aerogels at the single polymer chain level{sup 1,2}. With this level of structural resolution we hoped to interrelate each aerogel's structure with its physical properties and its method of synthesis. Conventional single-step base catalysed TMOS aerogels show strings of spheroidal particles linked together with minimal necking. The spheroidal particles range from 86--132 {Angstrom} and average 113{plus minus}10 {Angstrom} in diameter{sup 2}. In contrast the TMOS aerogels reported on here were made by a two step method. After extended silica chains are grown in solution under acidic conditions with a substoichiometric amount of water, the reaction is stopped and the methanol hydrolysed from TMOS is removed. Then base catalysis and additional water are added to cause gel formation is a nonalcoholic solvent. The MF aerogels were prepared for HRTEM by fracturing them on a stereo microscope stage with razor knife so that fractured pieces with smooth flat surfaces could be selected for platinum-carbon replication. The two silica (TMOS) aerogels were both transparent and difficult to see. These aerogels were fractured on a stereo microscope stage with tweezers. 6 refs., 4 figs.

  16. In-Situ High-Resolution Transmission Electron Microscopy Investigation of Overheating of Cu Nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, Chunlin; Hu, Ziyu; Li, Yanfen; Liu, Limin; Mori, Hirotaro; Wang, Zhangchang

    2016-01-01

    Synthesizing and functionalizing metal nanoparticles supported on substrates is currently the subject of intensive study owing to their outstanding catalytic performances for heterogeneous catalysis. Revealing the fundamental effect of the substrates on metal nanoparticles represents a key step in clarifying mechanisms of stability and catalytic properties of these heterogeneous systems. However, direct identification of these effects still poses a significant challenge due to the complicacy of interactions between substrates and nanoparticles and also for the technical difficulty, restraining our understanding of these heterogeneous systems. Here, we combine in situ high-resolution transmission electron microscopy with molecular dynamics simulations to investigate Cu nanoparticles supported on graphite and Cu2O substrates, and demonstrate that melting behavior and thermal stability of Cu nanoparticles can be markedly influenced by substrates. The graphite-supported Cu nanoparticles do not melt during annealing at 1073 K until they vanish completely, i.e. only the sublimation occurs, while the Cu2O-supported Cu nanoparticles suffer melting during annealing at 973 K. Such selective superheating of the Cu nanoparticles can be attributed to the adsorption of a thin carbon layer on the surface of the Cu nanoparticles, which helps guide further stability enhancement of functional nanoparticles for realistic applications.

  17. In-Situ High-Resolution Transmission Electron Microscopy Investigation of Overheating of Cu Nanoparticles.

    PubMed

    Chen, Chunlin; Hu, Ziyu; Li, Yanfen; Liu, Limin; Mori, Hirotaro; Wang, Zhangchang

    2016-01-01

    Synthesizing and functionalizing metal nanoparticles supported on substrates is currently the subject of intensive study owing to their outstanding catalytic performances for heterogeneous catalysis. Revealing the fundamental effect of the substrates on metal nanoparticles represents a key step in clarifying mechanisms of stability and catalytic properties of these heterogeneous systems. However, direct identification of these effects still poses a significant challenge due to the complicacy of interactions between substrates and nanoparticles and also for the technical difficulty, restraining our understanding of these heterogeneous systems. Here, we combine in situ high-resolution transmission electron microscopy with molecular dynamics simulations to investigate Cu nanoparticles supported on graphite and Cu2O substrates, and demonstrate that melting behavior and thermal stability of Cu nanoparticles can be markedly influenced by substrates. The graphite-supported Cu nanoparticles do not melt during annealing at 1073 K until they vanish completely, i.e. only the sublimation occurs, while the Cu2O-supported Cu nanoparticles suffer melting during annealing at 973 K. Such selective superheating of the Cu nanoparticles can be attributed to the adsorption of a thin carbon layer on the surface of the Cu nanoparticles, which helps guide further stability enhancement of functional nanoparticles for realistic applications. PMID:26785839

  18. High-Resolution 3-D Imaging and Tissue Differentiation with Transmission Tomography

    NASA Astrophysics Data System (ADS)

    Marmarelis, V. Z.; Jeong, J.; Shin, D. C.; Do, S.

    A three-dimensional High-resolution Ultrasonic Transmission Tomography (HUTT) system has been developed recently under the sponsorship of the Alfred Mann Institute at the University of Southern California that holds the promise of early detection of breast cancer (mm-size lesions) with greater sensitivity (true positives) and specificity (true negatives) than current x-ray mammograghy. In addition to sub-mm resolution in 3-D, the HUTT system has the unique capability of reliable tissue classification by means of the frequency-dependent attenuation characteristics of individual voxels that are extracted from the tomographic data through novel signal processing methods. These methods yield "multi-band signatures" of the various tissue types that are utilized to achieve reliable tissue differentiation via novel segmentation and classification algorithms. The unparalleled high-resolution and tissue differentiation capabilities of the HUTT system have been demonstrated so far with man-made and animal-tissue phantoms. Illustrative results are presented that corroborate these claims, although several challenges remain to make HUTT a clinically acceptable technology. The next critical step is to collect and analyze data from human subjects (female breasts) in order to demonstrate the key capability of the HUTT system to detect breast lesions early (at the mm-size stage) and to differentiate between malignant and benign lesions in a manner that is far superior (in terms of sensitivity and specificity) to the current x-ray mammography. The key initial application of the HUTT imaging technology is envisioned to be the early (at the mm-size) detection of breast cancer, which represents a major threat to the well-being of women around the world. The potential impact is estimated in hundreds of thousands lives saved, millions of unnecessary biopsies avoided, and billions of dollars saved in national health-care costs every year - to say nothing of the tens of thousands of

  19. Imaging Single Atoms Using Secondary Electrons with an Aberration-Corrected Electron Microscope

    SciTech Connect

    Zhu, Y.; Inada, H.; Nakamura, K.; Wall, J.

    2009-09-20

    Aberration correction has embarked on a new frontier in electron microscopy by overcoming the limitations of conventional round lenses, providing sub-angstrom-sized probes. However, improvement of spatial resolution using aberration correction so far has been limited to the use of transmitted electrons both in scanning and stationary mode, with an improvement of 20-40%. In contrast, advances in the spatial resolution of scanning electron microscopes (SEMs), which are by far the most widely used instrument for surface imaging at the micrometre-nanometre scale, have been stagnant, despite several recent efforts. Here, we report a new SEM, with aberration correction, able to image single atoms by detecting electrons emerging from its surface as a result of interaction with the small probe. The spatial resolution achieved represents a fourfold improvement over the best-reported resolution in any SEM. Furthermore, we can simultaneously probe the sample through its entire thickness with transmitted electrons. This ability is significant because it permits the selective visualization of bulk atoms and surface ones, beyond a traditional two-dimensional projection in transmission electron microscopy. It has the potential to revolutionize the field of microscopy and imaging, thereby opening the door to a wide range of applications, especially when combined with simultaneous nanoprobe spectroscopy.

  20. HIGH-RESOLUTION, DIFFERENTIAL, NEAR-INFRARED TRANSMISSION SPECTROSCOPY OF GJ 1214b

    SciTech Connect

    Crossfield, I. J. M.; Hansen, Brad M. S.; Barman, Travis

    2011-08-01

    The nearby star GJ 1214 hosts a planet intermediate in radius and mass between Earth and Neptune, resulting in some uncertainty as to its nature. We have observed this planet, GJ 1214b, during transit with the high-resolution, near-infrared NIRSPEC spectrograph on the Keck II telescope, in order to characterize the planet's atmosphere. By cross-correlating the spectral changes through transit with a suite of theoretical atmosphere models, we search for variations associated with absorption in the planet atmosphere. Our observations are sufficient to rule out tested model atmospheres with wavelength-dependent transit depth variations {approx}> 5 x 10{sup -4} over the wavelength range 2.1-2.4 {mu}m. Our sensitivity is limited by variable slit loss and telluric transmission effects. We find no positive signatures but successfully rule out a number of plausible atmospheric models, including the default assumption of a gaseous, H-dominated atmosphere in chemical equilibrium. Such an atmosphere can be made consistent if the absorption due to methane is reduced. Clouds can also render such an atmosphere consistent with our observations, but only if they lie higher in the atmosphere than indicated by recent optical and infrared measurements. When taken in concert with other observational constraints, our results support a model in which the atmosphere of GJ 1214b contains significant H and He, but where CH{sub 4} is depleted. If this depletion is the result of photochemical processes, it may also produce a haze that suppresses spectral features in the optical.

  1. High resolution transmission soft X-ray microscopy of deterioration products developed in large concrete dams

    PubMed

    Kurtis; Monteiro; Brown; Meyer-Ilse

    1999-12-01

    In concrete structures, the reaction of certain siliceous aggregates with the highly alkaline concrete pore solution produces an alkali-silicate gel that can absorb water and expand. This reaction can lead to expansion, cracking, increased permeability, and decreased strength of the concrete. Massive concrete structures, such as dams, are particularly susceptible to the damage caused by the alkali-silica reaction because of the availability of water and because massive gravity dams usually do not contain steel reinforcement to restrain the expansion. Both the cement hydration products and alkali-silica reaction products are extremely sensitive to humidity. Consequently, characterization techniques that require high vacuum or drying, as many existing techniques do, are not particularly appropriate for the study of the alkali-silica reaction because artefacts are introduced. Environmental scanning electron micrographs and scanning electron micrographs with energy dispersive X-ray analysis results demonstrate the effect of drying on the morphology and chemical composition of the alkali-silicate reaction gel. Thus, the impetus for this research was the need to observe and characterize the alkali-silica reaction and its gel product on a microscopic level in a wet environment (i.e. without introducing artefacts due to drying). Only soft X-ray transmission microscopy provides the required high spatial resolution needed to observe the reaction process in situ. The alkali-silica reaction can be observed over time, in a wet condition, and at normal pressures, features unavailable with most other high resolution techniques. Soft X-rays also reveal information on the internal structure of the sample. The purpose of this paper is to present research, obtained using transmission soft X-ray microscopy, on the effect of concrete pore solution cations, namely sodium and calcium, on the product formed as a result of alkali attack. Alkali-silicate reaction (ASR) gel was obtained from

  2. Lesion generation through ribs using histotripsy therapy without aberration correction.

    PubMed

    Kim, Yohan; Wang, Tzu-Yin; Xu, Zhen; Cain, Charles A

    2011-11-01

    This study investigates the feasibility of using high-intensity pulsed therapeutic ultrasound, or histotripsy, to non-invasively generate lesions through the ribs. Histotripsy therapy mechanically ablates tissue through the generation of a cavitation bubble cloud, which occurs when the focal pressure exceeds a certain threshold. We hypothesize that histotripsy can generate precise lesions through the ribs without aberration correction if the main lobe retains its shape and exceeds the cavitation initiation threshold and the secondary lobes remain below the threshold. To test this hypothesis, a 750-kHz focused transducer was used to generate lesions in tissue-mimicking phantoms with and without the presence of rib aberrators. In all cases, 8000 pulses with 16 to 18 MPa peak rarefactional pressure at a repetition frequency of 100 Hz were applied without aberration correction. Despite the high secondary lobes introduced by the aberrators, high-speed imaging showed that bubble clouds were generated exclusively at the focus, resulting in well-confined lesions with comparable dimensions. Collateral damage from secondary lobes was negligible, caused by single bubbles that failed to form a cloud. These results support our hypothesis, suggesting that histotripsy has a high tolerance for aberrated fields and can generate confined focal lesions through rib obstacles without aberration correction.

  3. Towards aberration correction of transcranial ultrasound using acoustic droplet vaporization.

    PubMed

    Haworth, Kevin J; Fowlkes, J Brian; Carson, Paul L; Kripfgans, Oliver D

    2008-03-01

    We report on the first experiments demonstrating the transcranial acoustic formation of stable gas bubbles that can be used for transcranial ultrasound aberration correction. It is demonstrated that the gas bubbles can be formed transcranially by phase-transitioning single, superheated, micron-size, liquid dodecafluoropentane droplets with ultrasound, a process known as acoustic droplet vaporization (ADV). ADV was performed at 550 kHz, where the skull is less attenuating and aberrating, allowing for higher-amplitudes to be reached at the focus. Additionally, it is demonstrated that time-reversal focusing at 1 MHz can be used to correct for transcranial aberrations with a single gas bubble acting as a point beacon. Aberration correction was performed using a synthetic aperture approach and verified by the realignment of the scattered waveforms. Under the conditions described below, time-reversal aberration correction using gas bubbles resulted in a gain of 1.9 +/- 0.3 in an introduced focusing factor. This is a small fraction of the gain anticipated from complete transmit-receive of a fully-populated two-dimensional array with sub-wavelength elements. (E-mail: khaworth@umich.edu).

  4. High-Resolution Transmission Electron Microscopy Observation of Colloidal Nanocrystal Growth Mechanisms using Graphene Liquid Cells

    SciTech Connect

    Yuk, Jong Min; Park, Jungwon; Ercius, Peter; Kim, Kwanpyo; Hellebusch, Danny J.; Crommie, Michael F.; Lee, Jeong Yong; Zettl, A.; Alivisatos, A. Paul

    2011-12-12

    We introduce a new type of liquid cell for in-situ electron microscopy based upon entrapment of a liquid film between layers of graphene. We employ this cell to achieve high-resolution imaging of colloidal platinum nanocrystal growth. The ability to directly image and resolve critical steps at atomic resolution provides new insights into nanocrystal coalescence and reshaping during growth.

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

    PubMed

    Brown, L Michael; Batson, Philip E; Dellby, Niklas; Krivanek, Ondrej L

    2015-10-01

    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.

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

    PubMed

    Brown, L Michael; Batson, Philip E; Dellby, Niklas; Krivanek, Ondrej L

    2015-10-01

    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. PMID:26094204

  7. High-Resolution 3D Imaging and Quantification of Gold Nanoparticles in a Whole Cell Using Scanning Transmission Ion Microscopy

    PubMed Central

    Chen, Xiao; Chen, Ce-Belle; Udalagama, Chammika N.B.; Ren, Minqin; Fong, Kah Ee; Yung, Lin Yue Lanry; Giorgia, Pastorin; Bettiol, Andrew Anthony; Watt, Frank

    2013-01-01

    Increasing interest in the use of nanoparticles (NPs) to elucidate the function of nanometer-sized assemblies of macromolecules and organelles within cells, and to develop biomedical applications such as drug delivery, labeling, diagnostic sensing, and heat treatment of cancer cells has prompted investigations into novel techniques that can image NPs within whole cells and tissue at high resolution. Using fast ions focused to nanodimensions, we show that gold NPs (AuNPs) inside whole cells can be imaged at high resolution, and the precise location of the particles and the number of particles can be quantified. High-resolution density information of the cell can be generated using scanning transmission ion microscopy, enhanced contrast for AuNPs can be achieved using forward scattering transmission ion microscopy, and depth information can be generated from elastically backscattered ions (Rutherford backscattering spectrometry). These techniques and associated instrumentation are at an early stage of technical development, but we believe there are no physical constraints that will prevent whole-cell three-dimensional imaging at <10 nm resolution. PMID:23561518

  8. Intrinsic instability of aberration-corrected electron microscopes.

    PubMed

    Schramm, S M; van der Molen, S J; Tromp, R M

    2012-10-19

    Aberration-corrected microscopes with subatomic 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.

  9. A High Resolution Full Field Transmission X-ray Microscope at SSRL

    SciTech Connect

    Luening, Katharina; Pianetta, Piero; Yun Wenbing; Almeida, Eduardo; Meulen, Marjolein van der

    2007-01-19

    The Stanford Synchrotron Radiation Laboratory (SSRL) in collaboration with Xradia Inc., the NASA Ames Research Center and Cornell University is implementing a commercial hard x-ray full field imaging microscope based on zone plate optics on a wiggler beam line on SPEAR3. This facility will provide unprecedented analytical capabilities for a broad range of scientific areas and will enable research on nanoscale phenomena and structures in biology as well as materials science and environmental science. This instrument will provide high resolution x-ray microscopy, tomography, and spectromicroscopy capabilities in a photon energy range between 5-14 keV. The spatial resolution of the TXM microscope is specified as 20 nm exploiting imaging in third diffraction order. This imaging facility will optimally combine the latest imaging technology developed by Xradia Inc. with the wiggler source characteristics at beam line 6-2 at SSRL. This will result in an instrument capable of high speed and high resolution imaging with spectral tunability for spectromicroscopy, element specific and Zernike phase contrast imaging. Furthermore, a scanning microprobe capability will be integral to the system thus allowing elemental mapping and fluorescence yield XANES to be performed with a spatial resolution of about 1 {mu}m without introducing any changes to the optical configuration of the instrument.

  10. A High Resolution Full Field Transmission X-ray Microscope at SSRL

    NASA Astrophysics Data System (ADS)

    Lüning, Katharina; Pianetta, Piero; Yun, Wenbing; Almeida, Eduardo; van der Meulen, Marjolein

    2007-01-01

    The Stanford Synchrotron Radiation Laboratory (SSRL) in collaboration with Xradia Inc., the NASA Ames Research Center and Cornell University is implementing a commercial hard x-ray full field imaging microscope based on zone plate optics on a wiggler beam line on SPEAR3. This facility will provide unprecedented analytical capabilities for a broad range of scientific areas and will enable research on nanoscale phenomena and structures in biology as well as materials science and environmental science. This instrument will provide high resolution x-ray microscopy, tomography, and spectromicroscopy capabilities in a photon energy range between 5-14 keV. The spatial resolution of the TXM microscope is specified as 20 nm exploiting imaging in third diffraction order. This imaging facility will optimally combine the latest imaging technology developed by Xradia Inc. with the wiggler source characteristics at beam line 6-2 at SSRL. This will result in an instrument capable of high speed and high resolution imaging with spectral tunability for spectromicroscopy, element specific and Zernike phase contrast imaging. Furthermore, a scanning microprobe capability will be integral to the system thus allowing elemental mapping and fluorescence yield XANES to be performed with a spatial resolution of about 1 μm without introducing any changes to the optical configuration of the instrument.

  11. High-resolution transmission electron microscopy of transformed magnesia-partially-stabilized zirconia precipitates

    SciTech Connect

    Wauchope, C.J.; Kelly, P.M.

    1995-10-01

    Transformed Mg-PSZ precipitates consist of monoclinic bands that are twin-related across either (100){sub m} or (001){sub m} planes in an arrangement that leads to accommodation of the shear component of the transformation shape strain. High-resolution images of these variants reveal these twin relationships quite clearly. It is shown that complete compensation of shear does not always occur. This paper also shows observations of monoclinic variants related by a rotation of 90{degree} around the normal to (001){sub m}, in addition to those related by a 180{degree} rotation for the twin-related variants. These findings conform to the predictions of martensite theory and their implications are discussed in terms of shear compensation and reduction in overall strain energy.

  12. High-resolution transmission electron microscopy of grain-refining particles in amorphous aluminum alloys

    SciTech Connect

    Schumacher, P.; Greer, A.L.

    1996-10-01

    The nucleation mechanism of Al-Ti-B grain refiners is studied in an Al-based amorphous alloy. The ability to limit growth of {alpha}-Al in the amorphous alloy permits the microscopical observation of nucleation events on boride particles. Earlier studies of this kind are extended by using high-resolution electron microscopy. This shows that the efficient nucleation {alpha}-Al depends on the TiB{sub 2} particles being coated with a thin layer of Al{sub 3}Ti, which can form only when there is some excess titanium in the melt. The aluminide layer, stabilized by adsorption effects, can be as little as a few monolayers thick, and is coherent with the boride. The nature of this layer, and its importance for the nucleation mechanism are discussed. The fading of the grain refinement action is also considered.

  13. Aberration-Corrected TEM Imaging of Oxygen Occupancy in YSZ.

    PubMed

    An, Jihwan; Koh, Ai Leen; Park, Joong Sun; Sinclair, Robert; Gür, Turgut M; Prinz, Fritz B

    2013-04-01

    We present atomic-scale imaging of oxygen columns and show quantitative analysis on the occupancy of the columns in yttria-stabilized zirconia (YSZ) using aberration-corrected TEM operated under the negative Cs condition. Also, individual contributions both from oxygen column occupancy and the static displacement of oxygen atoms due to occupancy change to the observed column intensities of TEM images were systematically investigated using HRTEM simulation. We found that oxygen column intensity is governed primarily by column occupancy rather than by static displacement of oxygen atoms. Utilizing the aberration-corrected TEM capability and HRTEM simulation results, we experimentally verified that oxygen vacancies segregate near the single grain boundary of a YSZ bicrystal. The methodology and the high spatial resolution characterization tool employed in the present study provide insights into the distribution of oxygen vacancies in the bulk as well as near grain boundaries and pave the way for further investigation and atomic-scale analysis in other important oxide materials.

  14. Direct imaging of lithium atoms in LiV₂O₄ by spherical aberration-corrected electron microscopy.

    PubMed

    Oshima, Yoshifumi; Sawada, Hidetaka; Hosokawa, Fumio; Okunishi, Eiji; Kaneyama, Toshikatsu; Kondo, Yukihito; Niitaka, Seiji; Takagi, Hidenori; Tanishiro, Yasumasa; Takayanagi, Kunio

    2010-01-01

    We visualized lithium atom columns in LiV₂O₄ crystals by combining scanning transmission electron microscopy with annular bright field (ABF) imaging using a spherical aberration-corrected electron microscope (R005) viewed from the [110] direction. The incident electron beam was coherent with a convergent angle of 30 mrad (semi-angle), and the detector collected scattered electrons over 20-30 mrad (semi-angle). The ABF image showed dark dots corresponding to lithium, vanadium and oxygen columns. PMID:20406731

  15. Packet based serial link realized in FPGA dedicated for high resolution infrared image transmission

    NASA Astrophysics Data System (ADS)

    Bieszczad, Grzegorz

    2015-05-01

    In article the external digital interface specially designed for thermographic camera built in Military University of Technology is described. The aim of article is to illustrate challenges encountered during design process of thermal vision camera especially related to infrared data processing and transmission. Article explains main requirements for interface to transfer Infra-Red or Video digital data and describes the solution which we elaborated based on Low Voltage Differential Signaling (LVDS) physical layer and signaling scheme. Elaborated link for image transmission is built using FPGA integrated circuit with built-in high speed serial transceivers achieving up to 2500Gbps throughput. Image transmission is realized using proprietary packet protocol. Transmission protocol engine was described in VHDL language and tested in FPGA hardware. The link is able to transmit 1280x1024@60Hz 24bit video data using one signal pair. Link was tested to transmit thermal-vision camera picture to remote monitor. Construction of dedicated video link allows to reduce power consumption compared to solutions with ASIC based encoders and decoders realizing video links like DVI or packed based Display Port, with simultaneous reduction of wires needed to establish link to one pair. Article describes functions of modules integrated in FPGA design realizing several functions like: synchronization to video source, video stream packeting, interfacing transceiver module and dynamic clock generation for video standard conversion.

  16. Spherical Aberration Corrections for the Electrostatic Gridded Lens

    SciTech Connect

    Pikin,A.

    2008-05-01

    Two methods of spherical aberration corrections of an electrostatic gridded lens have been studied with ray tracing simulations. Both methods are based on modifying electrostatic field on the periphery of the lens. In a simplest case such modification is done by extending the part of the grid support on its radial periphery in axial direction. In alternative method the electric field on the radial periphery of the lens is modified by applying an optimum voltage on an electrically isolated correcting electrode. It was demonstrated, that for a given focal length the voltage on this lens can be optimized for minimum aberration The performance of lenses is presented as a lens contribution to the beam RMS normalized emittance.

  17. Holographic optical system for aberration corrections in laser Doppler velocimetry

    NASA Technical Reports Server (NTRS)

    Kim, R. C.; Case, S. K.; Schock, H. J.

    1985-01-01

    An optical system containing multifaceted holographic optical elements (HOEs) has been developed to correct for aberrations introduced by nonflat windows in laser Doppler velocimetry. The multifacet aberration correction approach makes it possible to record on one plate many sets of adjacent HOEs that address different measurement volume locations. By using 5-mm-diameter facets, it is practical to place 10-20 sets of holograms on one 10 x 12.5-cm plate, so that the procedure of moving the entire optical system to examine different locations may not be necessary. The holograms are recorded in dichromated gelatin and therefore are nonabsorptive and suitable for use with high-power argon laser beams. Low f-number optics coupled with a 90-percent efficient distortion-correcting hologram in the collection side of the system yield high optical efficiency.

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

    PubMed

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

    2013-04-01

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

  19. Carbon Nanostructure Examined by Lattice Fringe Analysis of High Resolution Transmission Electron Microscopy Images

    NASA Technical Reports Server (NTRS)

    VanderWal, Randy L.; Tomasek, Aaron J.; Street, Kenneth; Thompson, William K.

    2002-01-01

    The dimensions of graphitic layer planes directly affect the reactivity of soot towards oxidation and growth. Quantification of graphitic structure could be used to develop and test correlations between the soot nanostructure and its reactivity. Based upon transmission electron microscopy images, this paper provides a demonstration of the robustness of a fringe image analysis code for determining the level of graphitic structure within nanoscale carbon, i.e. soot. Results, in the form of histograms of graphitic layer plane lengths, are compared to their determination through Raman analysis.

  20. Carbon Nanostructure Examined by Lattice Fringe Analysis of High Resolution Transmission Electron Microscopy Images

    NASA Technical Reports Server (NTRS)

    VanderWal, Randy L.; Tomasek, Aaron J.; Street, Kenneth; Thompson, William K.; Hull, David R.

    2003-01-01

    The dimensions of graphitic layer planes directly affect the reactivity of soot towards oxidation and growth. Quantification of graphitic structure could be used to develop and test correlations between the soot nanostructure and its reactivity. Based upon transmission electron microscopy images, this paper provides a demonstration of the robustness of a fringe image analysis code for determining the level of graphitic structure within nanoscale carbon, i.e., soot. Results, in the form of histograms of graphitic layer plane lengths, are compared to their determination through Raman analysis.

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

    DOEpatents

    de Jonge, Niels [Oak Ridge, TN

    2010-08-17

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

  2. Preparation of the planarian Schmidtea mediterranea for high-resolution histology and transmission electron microscopy

    PubMed Central

    Brubacher, John L.; Vieira, Ana P.; Newmark, Phillip A.

    2014-01-01

    The flatworm Schmidtea mediterranea is an emerging model species in such fields as stem-cell biology, regeneration, and evolutionary biology. Excellent molecular tools have been developed for S. mediterranea, but ultrastructural techniques have received far less attention. Processing specimens for histology and transmission electron microscopy is notoriously idiosyncratic for particular species or specimen types. Unfortunately however, most methods for S. mediterranea described in the literature lack numerous essential details, and those few that do provide them rely on specialized equipment that may not be readily available. Here we present an optimized protocol for ultrastructural preparation of S. mediterranea. The protocol can be completed in six days, much of which is “hands-off” time. To aid with troubleshooting, we also illustrate the significant effects of seemingly minor variations in fixative, buffer concentration, and dehydration steps. This procedure will be useful for all planarian researchers, particularly those with relatively little experience in tissue processing. PMID:24556788

  3. High Resolution Transmission Grating Spectrometer for Edge Toroidal Rotation Measurements of Tokamak Plasmas

    SciTech Connect

    Graf, A; May, M; Beiersdorfer, P; Magee, E; Lawrence, M; Terry, J; Rice, J

    2004-04-29

    We present a high throughput (f/3) visible (3500 - 7000 Angstrom) Doppler spectrometer for toroidal rotation velocity measurements of the Alcator C-Mod tokamak plasma. The spectrometer has a temporal response of 1 ms and a rotation velocity sensitivity of {approx}10{sup 5} cm/s. This diagnostic will have a tangential view and map out the plasma rotation at several locations along the outer half of the minor radius (r/a > 0.5). The plasma rotation will be determined from the Doppler shifted wavelengths of D{sub alpha} and magnetic and electric dipole transitions of highly ionized impurities in the plasma. The fast time resolution and high spectral resolving power are possible due to a 6' diameter circular transmission grating that is capable of {lambda}/{Delta}{lambda} {approx} 15500 at 5769 Angstrom in conjunction with a 50 {micro}m slit.

  4. Coalescence and sintering of Pt nanoparticles: in situ observation by aberration-corrected HAADF STEM.

    PubMed

    Asoro, M A; Kovar, D; Shao-Horn, Y; Allard, L F; Ferreira, P J

    2010-01-15

    An aberration-corrected JEOL 2200FS scanning-transmission electron microscope (STEM), equipped with a high-angle annular dark-field detector (HAADF), is used to monitor the coalescence and sintering of Pt nanoparticles with an average diameter of 2.8 nm. This in situ STEM capability is combined with an analysis methodology that together allows direct measurements of mass transport phenomena that are important in understanding how particle size influences coalescence and sintering at the nanoscale. To demonstrate the feasibility of this methodology, the surface diffusivity is determined from measurements obtained from STEM images acquired during the initial stages of sintering. The measured surface diffusivities are in reasonable agreement with measurements made on the surface of nanoparticles, using other techniques. In addition, the grain boundary mobility is determined from measurements made during the latter stages of sintering. PMID:19955618

  5. Coalescence and sintering of Pt nanoparticles: in situ observation by aberration-corrected HAADF STEM

    NASA Astrophysics Data System (ADS)

    Asoro, M. A.; Kovar, D.; Shao-Horn, Y.; Allard, L. F.; Ferreira, P. J.

    2010-01-01

    An aberration-corrected JEOL 2200FS scanning-transmission electron microscope (STEM), equipped with a high-angle annular dark-field detector (HAADF), is used to monitor the coalescence and sintering of Pt nanoparticles with an average diameter of 2.8 nm. This in situ STEM capability is combined with an analysis methodology that together allows direct measurements of mass transport phenomena that are important in understanding how particle size influences coalescence and sintering at the nanoscale. To demonstrate the feasibility of this methodology, the surface diffusivity is determined from measurements obtained from STEM images acquired during the initial stages of sintering. The measured surface diffusivities are in reasonable agreement with measurements made on the surface of nanoparticles, using other techniques. In addition, the grain boundary mobility is determined from measurements made during the latter stages of sintering.

  6. An aberration corrected photoemission electron microscope at the advanced light source

    SciTech Connect

    Feng, J.; MacDowell, A.A.; Duarte, R.; Doran, A.; Forest, E.; Kelez, N.; Marcus, M.; Munson, D.; Padmore, H.; Petermann, K.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stohr, J.; Wan, W.; Wei, D.H.; Wu, Y.

    2003-11-01

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

  7. Rotation and winds of exoplanet HD 189733 b measured with high-resolution transmission spectroscopy

    NASA Astrophysics Data System (ADS)

    Brogi, Matteo

    2015-12-01

    At the dawn of exoplanet science, the first discoveries revealed the existence of giant planets orbiting very close to their parent stars, called hot Jupiters. Early theories suggested that these planets should be tidally locked, although their spin rotation has never been measured directly. On top of rotation, hot Jupiters can show equatorial super-rotation via eastward jet streams and/or high-altitude winds flowing from the day- to the night-side hemisphere. All these patterns broaden and distort the planet spectral lines to an extent that is detectable with measurements at high spectral resolution.High-dispersion observations have recently excelled in robustly detecting molecules in the atmospheres of transiting and non-transiting hot Jupiters, and in measuring their relative abundances. Here the method is applied to the transmission spectrum of HD 189733 b, a Jupiter-size planet orbiting a K1-2V star in 2.2 days, observed around 2.3μm with CRIRES at the ESO Very Large Telescope. At a spectral resolution of R~100,000, the combined absorption of carbon monoxide and water vapor is detected in the planet spectrum at a confidence level of 7σ. The signal is obtained by cross correlating with theoretical spectra and it is maximized for a planet rotational velocity of 3.5+1.1-2.6 km/s. This corresponds to a planet rotational period of 1.7+4.9-0.4 days, consistent with the known orbital period of 2.2 days and therefore with tidal locking. Although planet rotations faster than 1.1 days can be ruled out at high confidence (3σ), sub-synchronous rotational velocities (Vrot < 2.7 km/s) or no-rotation are only marginally excluded (1.2σ). Finally, no significant day-to-night side winds are detected. When compared to the recent detection of sodium Doppler shifted by -8 km/s, this likely implies a strong wind shear between the atmospheric levels probed by these high-dispersion observations and the outermost atmospheric layers where the core of the sodium lines are formed.

  8. In vivo transcostal histotripsy therapy without aberration correction

    NASA Astrophysics Data System (ADS)

    Kim, Y.; Vlaisavljevich, E.; Owens, G. E.; Allen, S. P.; Cain, C. A.; Xu, Z.

    2014-06-01

    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.

  9. Seeing Inside Materials by Aberration-Corrected Electron Microscopy

    SciTech Connect

    Pennycook, Stephen J

    2011-01-01

    The recent successful correction of lens aberrations in the electron microscope has improved resolution by more than a factor of two in just a few years, bringing many benefits for the study of materials. These benefits extend significantly beyond enhanced resolution alone. Aberration correction gives higher resolution by allowing the objective lens to have a wider aperture, which also results in a reduced depth of field. This effect can be used to only focus specific sections inside materials for the first time. In this contribution we describe recent results exploiting this capability. Additionally, we show how combining the microscopy data with first-principles theory gives new insights into materials properties. We cover two applications, both involving heavy atoms in a lighter host. The first shows how single Hf atoms can be mapped in three dimensions inside the 1 nm-wide SiO2 region of a high dielectric constant device structure, and how a link to macroscopic device properties results through theoretical calculations. The second example is from the field of nanoscience, where individual Au atoms are imaged inside Si nanowires grown by a vapor-liquid-solid mechanism. The majority of Au atoms are probably injected by the highly energetic electron beam. However, their observed sites and atomic configurations represent at least meta-stable configurations and match well to results from density functional calculations.

  10. Phase aberration correction by correlation in digital holographic adaptive optics

    PubMed Central

    Liu, Changgeng; Yu, Xiao; Kim, Myung K.

    2013-01-01

    We present a phase aberration correction method based on the correlation between the complex full-field and guide-star holograms in the context of digital holographic adaptive optics (DHAO). Removal of a global quadratic phase term before the correlation operation plays an important role in the correction. Correlation operation can remove the phase aberration at the entrance pupil plane and automatically refocus the corrected optical field. Except for the assumption that most aberrations lie at or close to the entrance pupil, the presented method does not impose any other constraints on the optical systems. Thus, it greatly enhances the flexibility of the optical design for DHAO systems in vision science and microscopy. Theoretical studies show that the previously proposed Fourier transform DHAO (FTDHAO) is just a special case of this general correction method, where the global quadratic phase term and a defocus term disappear. Hence, this correction method realizes the generalization of FTDHAO into arbitrary DHAO systems. The effectiveness and robustness of this method are demonstrated by simulations and experiments. PMID:23669707

  11. Evolution of gold structure during thermal treatment of Au/FeOx catalysts revealed by aberration-corrected electron microscopy.

    PubMed

    Allard, Lawrence F; Borisevich, Albina; Deng, Weiling; Si, Rui; Flytzani-Stephanopoulos, Maria; Overbury, Steven H

    2009-06-01

    High-resolution aberration-corrected electron microscopy was performed on a series of catalysts derived from a parent material, 2 at.% Au/Fe(2)O(3) (WGC ref. no. 60C), prepared by co-precipitation and calcined in air at 400 degrees C, and a catalyst prepared by leaching surface gold from the parent catalyst and exposed to various treatments, including use in the water-gas shift reaction at 250 degrees C. Aberration-corrected JEOL 2200FS (JEOL USA, Peabody, MA) and Vacuum Generators HB-603U STEM instruments were used to image fresh, reduced, leached, used and re-oxidized catalyst samples. A new in situ heating technology (Protochips Inc., Raleigh, NC, USA), which permits full sub-Angström imaging resolution in the JEOL 2200FS was used to study the effects of temperature on the behavior of gold species. A remarkable stability of gold to redox treatments up to 400 degrees C, with atomic gold decorating step surfaces of iron oxide was identified. On heating the samples in vacuum to 700 degrees C, it was found that monodispersed gold began to sinter to form nanoparticles above 500 degrees C. Gold species internal to the iron oxide support material was shown to diffuse to the surface at elevated temperature, coalescing into discrete nanocrystals. The results demonstrate the value of in situ heating for understanding morphological changes in the catalyst with elevated temperature treatments.

  12. Characterization of Al2O3 in High-Strength Mo Alloy Sheets by High-Resolution Transmission Electron Microscopy.

    PubMed

    Zhou, Yucheng; Gao, Yimin; Wei, Shizhong; Hu, Yajie

    2016-02-01

    A novel type of alumina (Al2O3)-doped molybdenum (Mo) alloy sheet was prepared by a hydrothermal method and a subsequent powder metallurgy process. Then the characterization of α-Al2O3 was investigated using high-resolution transmission electron microscopy as the research focus. The tensile strength of the Al2O3-doped Mo sheet is 43-85% higher than that of the pure Mo sheet, a very obvious reinforcement effect. The sub-micron and nanometer-scale Al2O3 particles can increase the recrystallization temperature by hindering grain boundary migration and improve the tensile strength by effectively blocking the motion of the dislocations. The Al2O3 particles have a good bond with the Mo matrix and there exists an amorphous transition layer at the interface between Al2O3 particles and the Mo matrix in the as-rolled sheet. The sub-structure of α-Al2O3 is characterized by a number of nanograins in the $\\left[ {2\\bar{2}1} \\right]$ direction. Lastly, a new computer-based method for indexing diffraction patterns of the hexagonal system is introduced, with 16 types of diffraction patterns of α-Al2O3 indexed. PMID:26914997

  13. Genesis of presolar diamonds: Comparative high-resolution transmission electron microscopy study of meteoritic and terrestrial nano-diamonds

    SciTech Connect

    Daulton, T.L. |; Eisenhour, D.D.; Buseck, P.R.

    1996-12-01

    Nano-diamonds isolated from acid dissolution residues of primitive carbonaceous meteorites (Allende and Murchison) were studied using high-resolution transmission electron microscopy. To discriminate among their most likely formation mechanisms, high-pressure shock-induced metamorphism or low-pressure vapor condensation. the microstructures of presolar diamond crystallites were compared to those of (terrestrial) synthesized nano-diamonds. The synthesized diamonds used for comparison in this study were produced by high-pressure shock waves generated in controlled detonations and by direct nucleation and homoepitaxial growth from the vapor phase in low-pressure chemical vapor deposition (CVD)-type processes. Microstructural features were identified that appear unique to shock metamorphism and to nucleation from the vapor phase, respectively. A comparison of these features to the microstructures found in presolar diamonds indicates that the predominant mechanism for presolar diamond formation is a vapor deposition process, suggesting a circumstellar condensation origin. A new presolar grain component has also been identified in the meteoritic residues, the (2H) hexagonal polytype of diamond (lonsdaleite). 93 refs., 17 figs., 1 tab.

  14. Dense sampled transmission matrix for high resolution angular spectrum imaging through turbid media via compressed sensing (Conference Presentation)

    NASA Astrophysics Data System (ADS)

    Jang, Hwanchol; Yoon, Changhyeong; Choi, Wonshik; Eom, Tae Joong; Lee, Heung-No

    2016-03-01

    We provide an approach to improve the quality of image reconstruction in wide-field imaging through turbid media (WITM). In WITM, a calibration stage which measures the transmission matrix (TM), the set of responses of turbid medium to a set of plane waves with different incident angles, is preceded to the image recovery. Then, the TM is used for estimation of object image in image recovery stage. In this work, we aim to estimate highly resolved angular spectrum and use it for high quality image reconstruction. To this end, we propose to perform a dense sampling for TM measurement in calibration stage with finer incident angle spacing. In conventional approaches, incident angle spacing is made to be large enough so that the columns in TM are out of memory effect of turbid media. Otherwise, the columns in TM are correlated and the inversion becomes difficult. We employ compressed sensing (CS) for a successful high resolution angular spectrum recovery with dense sampled TM. CS is a relatively new information acquisition and reconstruction framework and has shown to provide superb performance in ill-conditioned inverse problems. We observe that the image quality metrics such as contrast-to-noise ratio and mean squared error are improved and the perceptual image quality is improved with reduced speckle noise in the reconstructed image. This results shows that the WITM performance can be improved only by executing dense sampling in the calibration stage and with an efficient signal reconstruction framework without elaborating the overall optical imaging systems.

  15. High-resolution transmission electron microscopy studies of quantum wire structures grown on submicrometre gratings of V-grooves

    NASA Astrophysics Data System (ADS)

    Gustafsson, A.; Malm, J.-O.; Carlsson, A.; Vermeire, G.

    1996-11-01

    We present an extensive characterization of a quantum wire (QWR) structure using transmission electron microscopy (TEM). The structure consisted of a single GaAs layer in between AlGaAs barriers, grown on a GaAs substrate patterned with a submicrometre grating of V-grooves. For reference we also studied other QWR, as well as, quantum well (QW) samples, fabricated under similar conditions. We used bright field and dark field imaging to study the overall structure, high-resolution TEM to study the layer thickness and the interface quality, and chemical lattice imaging to study the compositional variations across the interfaces. In the QWR sample, there were mainly two distinctly different areas of the QW: on the (100) planes between the V-grooves, the QW was flat, whereas the QW on the near 0268-1242/11/11/018/img5 side walls of the V-grooves had a flat lower interface and a saw-tooth shaped upper interface. The QWRs at the bottom of the V-grooves were crescent shaped. We also observed a fundamental difference in growth of the GaAs and the AlGaAs on the side wall, where the AlGaAs formed straight interfaces, determined by high-index planes, whereas the GaAs tended to form alternating low-index planes giving a saw-tooth appearance of the GaAs QW.

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

    NASA Astrophysics Data System (ADS)

    Boyes, E. D.; Gai, P. L.

    2014-06-01

    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.

  17. Quantification of the Information Limit of Transmission Electron Microscopes

    SciTech Connect

    Barthel, J.; Thust, A.

    2008-11-14

    The resolving power of high-resolution transmission electron microscopes is characterized by the information limit, which reflects the size of the smallest object detail observable with a particular instrument. We introduce a highly accurate measurement method for the information limit, which is suitable for modern aberration-corrected electron microscopes. An experimental comparison with the traditionally applied Young's fringe method yields severe discrepancies and confirms theoretical considerations according to which the Young's fringe method does not reveal the information limit.

  18. High Resolution Neutral Atom Microscope

    NASA Astrophysics Data System (ADS)

    Bucay, Igal; Castillo-Garza, Rodrigo; Stratis, Georgios; Raizen, Mark

    2015-03-01

    We are developing a high resolution neutral atom microscope based on metastable atom electron spectroscopy (MAES). When a metastable atom of a noble gas is near a solid, a surface electron will tunnel to an empty energy level of the metastable atom, thereby ejecting the excited electron from the atom. The emitted electrons carry information regarding the local topography and electronic, magnetic, and chemical structures of most hard materials. Furthermore, using a chromatic aberration corrected magnetic hexapole lens we expect to attain a spatial resolution below 10 nm. We will use this microscope to investigate how local phenomena can give rise to macroscopic effects in materials that cannot be probed using a scanning tunneling microscope, namely insulating transition metal oxides.

  19. In situ high-resolution transmission electron microscopy synthesis observation of nanostructured carbon coated LiFePO 4

    NASA Astrophysics Data System (ADS)

    Trudeau, M. L.; Laul, D.; Veillette, R.; Serventi, A. M.; Mauger, A.; Julien, C. M.; Zaghib, K.

    In situ high-resolution transmission electron microscopy (HRTEM) studies of the structural transformations that occur during the synthesis of carbon-coated LiFePO 4 (C-LiFePO 4) and heat treatment to elevated temperatures were conducted in two different electron microscopes. Both microscopes have sample holders that are capable of heating up to 1500 °C, with one working under high vacuum and the other capable of operating with the sample surrounded by a low gaseous environment. The C-LiFePO 4 samples were prepared using three different compositions of precursor materials with Fe(0), Fe(II) or Fe(III), a Li-containing salt and a polyethylene- block-poly(ethylene glycol)-50% ethylene oxide or lactose. The in situ TEM studies suggest that low-cost Fe(0) and a low-cost carbon-containing compound such as lactose are very attractive precursors for mass production of C-LiFePO 4, and that 700 °C is the optimum synthesis temperature. At temperatures higher than 800 °C, LiFePO 4 has a tendency to decompose. The same in situ measurements have been made on particles without carbon coat. The results show that the homogeneous deposit of the carbon deposit at 700 °C is the result of the annealing that cures the disorder of the surface layer of bare LiFePO 4. Electrochemical tests supported the conclusion that the C-LiFePO 4 derived from Fe(0) is the most attractive for mass production.

  20. Neutron irradiation damage of nuclear graphite studied by high-resolution transmission electron microscopy and Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Krishna, R.; Jones, A. N.; McDermott, L.; Marsden, B. J.

    2015-12-01

    Nuclear graphite components are produced from polycrystalline artificial graphite manufacture from a binder and filler coke with approximately 20% porosity. During the operational lifetime, nuclear graphite moderator components are subjected to fast neutron irradiation which contributes to the change of material and physical properties such as thermal expansion co-efficient, young's modulus and dimensional change. These changes are directly driven by irradiation-induced changes to the crystal structure as reflected through the bulk microstructure. It is therefore of critical importance that these irradiation changes and there implication on component property changes are fully understood. This work examines a range of irradiated graphite samples removed from the British Experimental Pile Zero (BEPO) reactor; a low temperature, low fluence, air-cooled Materials Test Reactor which operated in the UK. Raman spectroscopy and high-resolution transmission electron microscopy (HRTEM) have been employed to characterise the effect of increased irradiation fluence on graphite microstructure and understand low temperature irradiation damage processes. HRTEM confirms the structural damage of the crystal lattice caused by irradiation attributed to a high number of defects generation with the accumulation of dislocation interactions at nano-scale range. Irradiation-induced crystal defects, lattice parameters and crystallite size compared to virgin nuclear graphite are characterised using selected area diffraction (SAD) patterns in TEM and Raman Spectroscopy. The consolidated 'D'peak in the Raman spectra confirms the formation of in-plane point defects and reflected as disordered regions in the lattice. The reduced intensity and broadened peaks of 'G' and 'D' in the Raman and HRTEM results confirm the appearance of turbulence and disordering of the basal planes whilst maintaining their coherent layered graphite structure.

  1. Theoretical aspects of image formation in the aberration-corrected electron microscope.

    PubMed

    Rose, H

    2010-04-01

    The theoretical aspects of image formation in the transmission electron microscope (TEM) are outlined and revisited in detail by taking into account the elastic and inelastic scattering. In particular, the connection between the exit wave and the scattering amplitude is formulated for non-isoplanatic conditions. Different imaging modes are investigated by utilizing the scattering amplitude and employing the generalized optical theorem. A novel obstruction-free anamorphotic phase shifter is proposed which enables one to shift the phase of the scattered wave by an arbitrary amount over a large range of spatial frequencies. In the optimum case, the phase of the scattered wave and the introduced phase shift add up to -pi/2 giving negative contrast. We obtain these optimum imaging conditions by employing an aberration-corrected electron microscope operating at voltages below the knock-on threshold for atom displacement and by shifting optimally the phase of the scattered electron wave. The optimum phase shift is achieved by adjusting appropriately the constant phase shift of the phase plate and the phase shift resulting from the defocus and the spherical aberration of the corrected objective lens. The realization of this imaging mode is the aim of the SALVE project (Sub-A Low-Voltage Electron microscope).

  2. Nanoscale analysis of unstained biological specimens in water without radiation damage using high-resolution frequency transmission electric-field system based on FE-SEM

    SciTech Connect

    Ogura, Toshihiko

    2015-04-10

    Scanning electron microscopy (SEM) has been widely used to examine biological specimens of bacteria, viruses and proteins. Until now, atmospheric and/or wet biological specimens have been examined using various atmospheric holders or special equipment involving SEM. Unfortunately, they undergo heavy radiation damage by the direct electron beam. In addition, images of unstained biological samples in water yield poor contrast. We recently developed a new analytical technology involving a frequency transmission electric-field (FTE) method based on thermionic SEM. This method is suitable for high-contrast imaging of unstained biological specimens. Our aim was to optimise the method. Here we describe a high-resolution FTE system based on field-emission SEM; it allows for imaging and nanoscale examination of various biological specimens in water without radiation damage. The spatial resolution is 8 nm, which is higher than 41 nm of the existing FTE system. Our new method can be easily utilised for examination of unstained biological specimens including bacteria, viruses and protein complexes. Furthermore, our high-resolution FTE system can be used for diverse liquid samples across a broad range of scientific fields, e.g. nanoparticles, nanotubes and organic and catalytic materials. - Highlights: • We developed a high-resolution frequency transmission electric-field (FTE) system. • High-resolution FTE system is introduced in the field-emission SEM. • The spatial resolution of high-resolution FTE method is 8 nm. • High-resolution FTE system enables observation of the intact IgM particles in water.

  3. Adaptive Optics Analysis of Visual Benefit with Higher-order Aberrations Correction of Human Eye - Poster Paper

    NASA Astrophysics Data System (ADS)

    Xue, Lixia; Dai, Yun; Rao, Xuejun; Wang, Cheng; Hu, Yiyun; Liu, Qian; Jiang, Wenhan

    2008-01-01

    Higher-order aberrations correction can improve visual performance of human eye to some extent. To evaluate how much visual benefit can be obtained with higher-order aberrations correction we developed an adaptive optics vision simulator (AOVS). Dynamic real time optimized modal compensation was used to implement various customized higher-order ocular aberrations correction strategies. The experimental results indicate that higher-order aberrations correction can improve visual performance of human eye comparing with only lower-order aberration correction but the improvement degree and higher-order aberration correction strategy are different from each individual. Some subjects can acquire great visual benefit when higher-order aberrations were corrected but some subjects acquire little visual benefit even though all higher-order aberrations were corrected. Therefore, relative to general lower-order aberrations correction strategy, customized higher-order aberrations correction strategy is needed to obtain optimal visual improvement for each individual. AOVS provides an effective tool for higher-order ocular aberrations optometry for customized ocular aberrations correction.

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

    SciTech Connect

    Vyas, Urvi Kaye, Elena; Pauly, Kim Butts

    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.

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

    PubMed

    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.

  6. Interface characterization of XUV multilayer reflectors using HRTEM (high-resolution transmission electron microscopy) and x-ray and XUV reflectance

    SciTech Connect

    Windt, D.L.; Hull, R.; Waskiewicz, W.K.; Kortright, J.B.

    1990-07-01

    We have examined the structure of XUV multilayer coatings using high-resolution transmission electron microscopy (HRTEM). Using a variety of techniques, we have measured the interface widths and the interface topography from the digitized TEM images, and have compared these results to x-ray and XUV reflectance measurements. We find that the structural parameters measured from the TEM images and those deduced from reflectance are consistent in light of the probable systematic errors associated with the measurement and interpretation techniques. 14 refs., 12 figs., 1 tab.

  7. High-resolution chemical analysis by STEM-EELS of nanosized oxide particles in a mechanically-alloyed FeCrAl intermetallic

    SciTech Connect

    Morris, D.G. Muñoz-Morris, M.A.

    2015-05-15

    The chemical composition of nanosized oxides has been analysed in a mechanically-alloyed (MA) iron–chromium–aluminium intermetallic containing yttria additions using an aberration-corrected, high-resolution scanning transmission electron microscope (STEM). The oxide particles are seen to contain yttrium and oxygen only, but very little of the matrix metallic elements, while the matrix in the immediate vicinity shows a very low iron content. Possible reasons for the change of matrix composition outside the particle-matrix interface are discussed. - Highlights: • High-resolution chemical analysis of oxide particles was performed using STEM-EELS. • Oxide particles contain Y and O but essentially no elements from the Fe–Cr–Al matrix. • The matrix immediately outside the particles appears to be depleted in Fe. • Diffusion of Y during particle growth possibly transports vacancies to the interface.

  8. Identifying the crystallinity, phase, and arsenic uptake of the nanomineral schwertmannite using analytical high resolution transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    French, R. A.; Kim, B.; Murayama, M.; Hochella, M. F.

    2010-12-01

    Schwertmannite, an iron oxyhydroxide sulfate nanomineral, plays a significant role in the geochemistry of acid mine drainage (AMD) as a metastable phase with respect to goethite and by retaining toxic metals, e.g. arsenic [1]. Schwertmannite’s characteristic morphology is needles 100-300 nm long and only 5-10 nm in diameter extending from a dense aggregate. The poorly-and nano-crystalline nature of this mineral requires using high resolution electron microscopy (HRTEM) to be fully characterized. We used HRTEM to identify the polyphasic nature of natural samples of schwertmannite collected from the Iberian Pyrite Belt in Spain. In order to analyze the dense core, samples were prepared in thin section using an ultramicrotome. Data on a sample identified as pure schwertmannite through powder XRD shows the presence of 5-10 nm goethite nanocrystals making up a significant portion of one of the nanoneedle tips (Figure 1). These nanocrystals exhibit lattice fringes and faceted surfaces, both of which match that expected for goethite. The great majority of the nanoneedles are poorly-crystalline (no lattice fringes) with atomically rough surfaces which may be highly active in the uptake of As. The presence of a range of phases and crystallinities in this sample demonstrate incipient stages of the mechanism that results in transformation of schwertmannite to goethite. Further analytical TEM analyses will help us track sorption/desorption, as well as the specific locations of As within these materials upon initial formation, as well as during transformation. [1] Acero et al. (2006) GCA 70, 4130-4139. Figure 1. HRTEM image of 'schwertmannite' nanoneedle with FFT data (inset).

  9. Zone-doubled Fresnel zone plates for high-resolution hard X-ray full-field transmission microscopy

    PubMed Central

    Vila-Comamala, Joan; Pan, Yongsheng; Lombardo, Jeffrey J.; Harris, William M.; Chiu, Wilson K. S.; David, Christian; Wang, Yuxin

    2012-01-01

    Full-field transmission X-ray microscopy is a unique non-destructive technique for three-dimensional imaging of specimens at the nanometer scale. Here, the use of zone-doubled Fresnel zone plates to achieve a spatial resolution better than 20 nm in the hard X-ray regime (8–10 keV) is reported. By obtaining a tomographic reconstruction of a Ni/YSZ solid-oxide fuel cell, the feasibility of performing three-dimensional imaging of scientifically relevant samples using such high-spatial-resolution Fresnel zone plates is demonstrated. PMID:22898949

  10. Temporal integration property of stereopsis after higher-order aberration correction

    PubMed Central

    Kang, Jian; Dai, Yun; Zhang, Yudong

    2015-01-01

    Based on a binocular adaptive optics visual simulator, we investigated the effect of higher-order aberration correction on the temporal integration property of stereopsis. Stereo threshold for line stimuli, viewed in 550nm monochromatic light, was measured as a function of exposure duration, with higher-order aberrations uncorrected, binocularly corrected or monocularly corrected. Under all optical conditions, stereo threshold decreased with increasing exposure duration until a steady-state threshold was reached. The critical duration was determined by a quadratic summation model and the high goodness of fit suggested this model was reasonable. For normal subjects, the slope for stereo threshold versus exposure duration was about −0.5 on logarithmic coordinates, and the critical duration was about 200 ms. Both the slope and the critical duration were independent of the optical condition of the eye, showing no significant effect of higher-order aberration correction on the temporal integration property of stereopsis. PMID:26601010

  11. High resolution Bragg edge transmission spectroscopy at pulsed neutron sources: Proof of principle experiments with a neutron counting MCP detector

    NASA Astrophysics Data System (ADS)

    Tremsin, A. S.; McPhate, J. B.; Kockelmann, W.; Vallerga, J. V.; Siegmund, O. H. W.; Feller, W. B.

    2011-05-01

    The high spatial and temporal resolution of a neutron counting detector using microchannel plates (MCPs) combined with Medipix2/Timepix readout can substantially improve the spatial resolution of neutron transmission spectroscopy, as shown in our proof-of-principle experiments. Provided that the neutron fluence and data acquisition time are sufficient, transmission spectra can be acquired in each 55×55 μm2 pixel of the detector, allowing high spatial resolution mapping of Bragg edge positions. Our first experiment demonstrates that energy resolution as high as ΔE/E<1% or ΔE<4 mÅ can be achieved. Variation of the residual strain in a well-characterized VAMAS round robin shrink-fitted Al ring-and-plug sample was measured with ˜200 microstrain resolution through an accurate mapping of the first (1 1 1) Bragg edge. The measured stress profile agrees well with the expected values for that particular sample. More developments on the detector processing electronics are required in order to reduce the data acquisition times by enabling simultaneous measurements of spectra in a wide energy range covering multiple Bragg edges.

  12. Optimal experimental design for the detection of light atoms from high-resolution scanning transmission electron microscopy images

    SciTech Connect

    Gonnissen, J.; De Backer, A.; Martinez, G. T.; Van Aert, S.; Dekker, A. J. den; Rosenauer, A.; Sijbers, J.

    2014-08-11

    We report an innovative method to explore the optimal experimental settings to detect light atoms from scanning transmission electron microscopy (STEM) images. Since light elements play a key role in many technologically important materials, such as lithium-battery devices or hydrogen storage applications, much effort has been made to optimize the STEM technique in order to detect light elements. Therefore, classical performance criteria, such as contrast or signal-to-noise ratio, are often discussed hereby aiming at improvements of the direct visual interpretability. However, when images are interpreted quantitatively, one needs an alternative criterion, which we derive based on statistical detection theory. Using realistic simulations of technologically important materials, we demonstrate the benefits of the proposed method and compare the results with existing approaches.

  13. Nanoscale analysis of unstained biological specimens in water without radiation damage using high-resolution frequency transmission electric-field system based on FE-SEM.

    PubMed

    Ogura, Toshihiko

    2015-04-10

    Scanning electron microscopy (SEM) has been widely used to examine biological specimens of bacteria, viruses and proteins. Until now, atmospheric and/or wet biological specimens have been examined using various atmospheric holders or special equipment involving SEM. Unfortunately, they undergo heavy radiation damage by the direct electron beam. In addition, images of unstained biological samples in water yield poor contrast. We recently developed a new analytical technology involving a frequency transmission electric-field (FTE) method based on thermionic SEM. This method is suitable for high-contrast imaging of unstained biological specimens. Our aim was to optimise the method. Here we describe a high-resolution FTE system based on field-emission SEM; it allows for imaging and nanoscale examination of various biological specimens in water without radiation damage. The spatial resolution is 8 nm, which is higher than 41 nm of the existing FTE system. Our new method can be easily utilised for examination of unstained biological specimens including bacteria, viruses and protein complexes. Furthermore, our high-resolution FTE system can be used for diverse liquid samples across a broad range of scientific fields, e.g. nanoparticles, nanotubes and organic and catalytic materials. PMID:25747717

  14. Nanoscale analysis of unstained biological specimens in water without radiation damage using high-resolution frequency transmission electric-field system based on FE-SEM.

    PubMed

    Ogura, Toshihiko

    2015-04-10

    Scanning electron microscopy (SEM) has been widely used to examine biological specimens of bacteria, viruses and proteins. Until now, atmospheric and/or wet biological specimens have been examined using various atmospheric holders or special equipment involving SEM. Unfortunately, they undergo heavy radiation damage by the direct electron beam. In addition, images of unstained biological samples in water yield poor contrast. We recently developed a new analytical technology involving a frequency transmission electric-field (FTE) method based on thermionic SEM. This method is suitable for high-contrast imaging of unstained biological specimens. Our aim was to optimise the method. Here we describe a high-resolution FTE system based on field-emission SEM; it allows for imaging and nanoscale examination of various biological specimens in water without radiation damage. The spatial resolution is 8 nm, which is higher than 41 nm of the existing FTE system. Our new method can be easily utilised for examination of unstained biological specimens including bacteria, viruses and protein complexes. Furthermore, our high-resolution FTE system can be used for diverse liquid samples across a broad range of scientific fields, e.g. nanoparticles, nanotubes and organic and catalytic materials.

  15. STEM imaging of 47-pm-separated atomic columns by a spherical aberration-corrected electron microscope with a 300-kV cold field emission gun.

    PubMed

    Sawada, Hidetaka; Tanishiro, Yasumasa; Ohashi, Nobuhiro; Tomita, Takeshi; Hosokawa, Fumio; Kaneyama, Toshikatsu; Kondo, Yukihito; Takayanagi, Kunio

    2009-12-01

    A spherical aberration-corrected electron microscope has been developed recently, which is equipped with a 300-kV cold field emission gun and an objective lens of a small chromatic aberration coefficient. A dumbbell image of 47 pm spacing, corresponding to a pair of atomic columns of germanium aligned along the [114] direction, is resolved in high-angle annular dark field (HAADF) scanning transmission electron microscopy (STEM) with a 0.4-eV energy spread of the electron beam. The observed image was compared with a simulated image obtained by dynamical calculation.

  16. In situ fabrication and optoelectronic analysis of axial CdS/p-Si nanowire heterojunctions in a high-resolution transmission electron microscope.

    PubMed

    Zhang, Chao; Xu, Zhi; Tian, Wei; Tang, Dai-Ming; Wang, Xi; Bando, Yoshio; Fukata, Naoki; Golberg, Dmitri

    2015-04-17

    A high-precision technique was utilized to construct and characterize axial nanowire heterojunctions inside a high-resolution transmission electron microscope (HRTEM). By an in-tandem technique using an ultra-sharp tungsten probe as the nanomanipulator and an optical fiber as the optical waveguide the nanoscale CdS/p-Si axial nanowire junctions were fabricated, and in situ photocurrents from them were successfully measured. Compared to a single constituting nanowire, the CdS/p-Si axial nanowire junctions possess a photocurrent saturation effect, which protects them from damage under high voltages. Furthermore, a set of experiments reveals the clear relationship between the saturation photocurrent values and the incident light intensities. The applied technique is expected to be valuable for bottom-up nanodevice fabrications, and the regarded photocurrent saturation feature may solve the Joule heating-induced failure problem in nanowire optoelectronic devices caused by a fluctuating bias. PMID:25797523

  17. Atomic arrangement at ZnTe/CdSe interfaces determined by high resolution scanning transmission electron microscopy and atom probe tomography

    SciTech Connect

    Bonef, Bastien; Rouvière, Jean-Luc; Jouneau, Pierre-Henri; Bellet-Amalric, Edith; Gérard, Lionel; Mariette, Henri; André, Régis; Bougerol, Catherine; Grenier, Adeline

    2015-02-02

    High resolution scanning transmission electron microscopy and atom probe tomography experiments reveal the presence of an intermediate layer at the interface between two binary compounds with no common atom, namely, ZnTe and CdSe for samples grown by Molecular Beam Epitaxy under standard conditions. This thin transition layer, of the order of 1 to 3 atomic planes, contains typically one monolayer of ZnSe. Even if it occurs at each interface, the direct interface, i.e., ZnTe on CdSe, is sharper than the reverse one, where the ZnSe layer is likely surrounded by alloyed layers. On the other hand, a CdTe-like interface was never observed. This interface knowledge is crucial to properly design superlattices for optoelectronic applications and to master band-gap engineering.

  18. Opto-mechano-electrical tripling in ZnO nanowires probed by photocurrent spectroscopy in a high-resolution transmission electron microscope

    SciTech Connect

    Zhang, C.; Golberg, D. E-mail: golberg.dmitri@nims.go.jp; Xu, Z. E-mail: golberg.dmitri@nims.go.jp; Kvashnin, D. G.; Tang, D.-M.; Xue, Y. M.; Bando, Y.; Sorokin, P. B.

    2015-08-31

    Photocurrent spectroscopy of individual free-standing ZnO nanowires inside a high-resolution transmission electron microscope (TEM) is reported. By using specially designed optical in situ TEM system capable of scanning tunneling microscopy probing paired with light illumination, opto-mechano-electrical tripling phenomenon in ZnO nanowires is demonstrated. Splitting of photocurrent spectra at around 3.3 eV under in situ TEM bending of ZnO nanowires directly corresponds to nanowire deformation and appearance of expanded and compressed nanowire sides. Theoretical simulation of a bent ZnO nanowire has an excellent agreement with the experimental data. The splitting effect could be explained by a change in the valence band structure of ZnO nanowires due to a lattice strain. The strain-induced splitting provides important clues for future flexible piezo-phototronics.

  19. Air temperature suitability for Plasmodium falciparum malaria transmission in Africa 2000-2012: a high-resolution spatiotemporal prediction

    PubMed Central

    2014-01-01

    Background Temperature suitability for malaria transmission is a useful predictor variable for spatial models of malaria infection prevalence. Existing continental or global models, however, are synoptic in nature and so do not characterize inter-annual variability in seasonal patterns of temperature suitability, reducing their utility for predicting malaria risk. Methods A malaria Temperature Suitability Index (TSI) was created by first modeling minimum and maximum air temperature with an eight-day temporal resolution from gap-filled MODerate Resolution Imaging Spectroradiometer (MODIS) daytime and night-time Land Surface Temperature (LST) datasets. An improved version of an existing biological model for malaria temperature suitability was then applied to the resulting temperature information for a 13-year data series. The mechanism underlying this biological model is simulation of emergent mosquito cohorts on a two-hour time-step and tracking of each cohort throughout its life to quantify the impact air temperature has on both mosquito survival and sporozoite development. Results The results of this research consist of 154 monthly raster surfaces that characterize spatiotemporal patterns in TSI across Africa from April 2000 through December 2012 at a 1 km spatial resolution. Generalized TSI patterns were as expected, with consistently high values in equatorial rain forests, seasonally variable values in tropical savannas (wet and dry) and montane areas, and low values in arid, subtropical regions. Comparisons with synoptic approaches demonstrated the additional information available within the dynamic TSI dataset that is lost in equivalent synoptic products derived from long-term monthly averages. Conclusions The dynamic TSI dataset presented here provides a new product with far richer spatial and temporal information than any other presently available for Africa. As spatiotemporal malaria modeling endeavors evolve, dynamic predictor variables such as the malaria

  20. Aberration-corrected STEM imaging of Ag on gamma-Al2O3.

    PubMed

    Blom, Douglas A; Allard, Lawrence F; Narula, Chaitanya K; Moses-DeBusk, Melanie J

    2008-02-01

    Ag on gamma-alumina is a promising catalyst for hydrocarbon selective catalytic reduction in lean-burn gasoline and diesel engines for transportation applications. Although much is known about the mechanism of NOx reduction and the various intermediates, little agreement exists on the nature of the active silver species. In the present work, aberration-corrected STEM has provided new information about the nature of Ag on alumina both as impregnated and following treatments at various temperatures with exposure to simulated exhaust gas. Ex situ techniques have provided new insights into the evolution of Ag on alumina following exposure to temperature and simulated exhaust gas.

  1. Microstructure analysis of epitaxially grown self-assembled Ge islands on nanometer-scale patterned SiO2/Si substrates by high-resolution transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Yoon, Tae-Sik; Kim, Hyun-Mi; Kim, Ki-Bum; Ryu, Du Yeol; Russell, Thomas P.; Zhao, Zuoming; Liu, Jian; Xie, Ya-Hong

    2007-11-01

    The microstructure of epitaxially grown self-assembled Ge islands on patterned SiO2/Si substrates was analyzed using high resolution transmission electron microscopy. The Ge islands were grown by molecular beam epitaxy on hexagonally ordered Si hole arrays with ˜25 nm diameter and ˜40 nm center-to-center distance, which are covered by 30 nm thick SiO2 mask layer patterned using self-assembled diblock copolymers. The Ge islands nucleate preferentially at the edge of overetched Si surface, and subsequently grow selectively on Si surface as opposed to SiO2 surface with increasing coverage. The lattice planes of some Ge islands are tilted from those of Si substrates. This is believed to be the reason for the observed misalignment of moiré fringes. The diameter of the Ge islands is identical to that of Si holes for large Ge coverage due to the selective growth behavior. These islands are found to have dislocations at the interface with the Si substrate. These results highlight the important microstructural issues and growth behavior of quantum dots on patterned substrates.

  2. Structure analysis of new homologous compounds Ga2O3(ZnO)m (m = integer) by high-resolution analytical transmission electron microscopy.

    PubMed

    Li; Bando; Nakamura; Kurashima; Kimizuka

    1999-06-01

    The crystal structure of a new homologous compound series, Ga(2)O(3)(ZnO)(m) (m = integer), is determined by high-resolution lattice imaging and high spatial resolution energy-dispersive X-ray spectroscopy (EDS) analysis in a field-emission analytical transmission electron microscope. This work was carried out mainly on the compound with m = 9 (digallium nonazinc dodecaoxide), which belongs to the orthorhombic system and has lattice constants a(o) = 0.33, b(o) = 2.0 and c(o) = 3.4 nm. From the extinction rules three possible space groups are selected and from them a unique space group is assigned as noncentrosymmetric Cmc2(1) (No. 36) on the basis of structural requirements. Ga(2)O(3)(ZnO)(m) is a layered structure consisting of Ga-O and m + 1 Ga/Zn-O layers stacked alternately along the c axis. It is shown that the structure of Ga(2)O(3)(ZnO)(m) differs from that of M(2)O(3)(ZnO)(m) (M = In, Fe; m = integer) reported previously. In Ga(2)O(3)(ZnO)(m) the Ga atoms occupy the tetrahedral sites in the Ga-O layers, whereas the M atoms in the M-O layers occupy the octahedral sites in M(2)O(3)(ZnO)(m) (M = In, Fe).

  3. High-resolution transmission electron microscopy study of solid phase crystallized silicon thin films on SiO2: Crystal growth and defects formation

    NASA Astrophysics Data System (ADS)

    Kim, J. H.; Lee, J. Y.; Nam, K. S.

    1995-01-01

    A high-resolution transmission electron microscopy study of the solid phase crystallization of amorphous silicon thin films deposited on SiO2 at 520 C by low pressure chemical vapor deposition and annealed at 550 C in a dry N2 ambient was carried out so that the grain growth mechanism, various types of defects, and the origins of defect formation could be understood on an atomic level. Silicon crystallites formed at the initial stage of the crystallization had a circular shape and grains had a branched elliptical or a dendritic shape. Many twins, of which (111) coherent boundaries were parallel to the long axis of a grain, were observed in the interior of all the elongated grains. In addition to twins, the following defects are observed in the grain: intrinsic stacking faults, extrinsic stacking faults, perfect dislocations, extended screw dislocations, and Shockley partial dislocations. These defects were formed by the following reasons: errors in the stacking sequence at the amorphous/crystalline interface; jumps of a twin plane; the intersecting of two crystal growth fronts slightly misoriented; and the intersecting of two twin planes at the amorphous/crystalline interface. Among those defects, twins and stacking faults provided a preferable nucleation site for an atomic step of a (111) plane. As a result, it was concluded that grain growth in the (112) direction along the (111) plane parallel to the long axis of a grain was accelerated by twins and stacking faults.

  4. Development of a monochromator for aberration-corrected scanning transmission electron microscopy.

    PubMed

    Mukai, Masaki; Okunishi, Eiji; Ashino, Masanori; Omoto, Kazuya; Fukuda, Tomohisa; Ikeda, Akihiro; Somehara, Kazunori; Kaneyama, Toshikatsu; Saitoh, Tomohiro; Hirayama, Tsukasa; Ikuhara, Yuichi

    2015-06-01

    In this article, we report the development of a new 200-kV analytical electron microscope equipped with a monochromator with an integrated double Wien-filter system. It enables us to study the electronic structures of materials in detail using electron energy-loss spectroscopy (EELS) analysis at an atomic scale. A highly monochromated and isotropically round electron probe is produced on the specimen plane. The ultimate energy resolutions with 0.1-s acquisition times are measured to be 36 meV at 200 kV and 30 meV at 60 kV. In an EELS mapping experiment performed on SrTiO3 with a monochromated electron probe whose energy resolution is 146 meV, an elemental map exhibits atomic resolution.

  5. Model-based sensor-less wavefront aberration correction in optical coherence tomography.

    PubMed

    Verstraete, Hans R G W; Wahls, Sander; Kalkman, Jeroen; Verhaegen, Michel

    2015-12-15

    Several sensor-less wavefront aberration correction methods that correct nonlinear wavefront aberrations by maximizing the optical coherence tomography (OCT) signal are tested on an OCT setup. A conventional coordinate search method is compared to two model-based optimization methods. The first model-based method takes advantage of the well-known optimization algorithm (NEWUOA) and utilizes a quadratic model. The second model-based method (DONE) is new and utilizes a random multidimensional Fourier-basis expansion. The model-based algorithms achieve lower wavefront errors with up to ten times fewer measurements. Furthermore, the newly proposed DONE method outperforms the NEWUOA method significantly. The DONE algorithm is tested on OCT images and shows a significantly improved image quality. PMID:26670496

  6. Design of macro-filter-lens with simultaneous chromatic and geometric aberration correction.

    PubMed

    Prasad, Dilip K; Brown, Michael S

    2014-01-01

    A macro-filter-lens design that can correct for chromatic and geometric aberrations simultaneously while providing for a long focal length is presented. The filter is easy to fabricate since it involves two spherical surfaces and a planar surface. Chromatic aberration correction is achieved by making all the rays travel the same optical distance inside the filter element (negative meniscus). Geometric aberration is corrected for by the lens element (plano-convex), which makes the output rays parallel to the optic axis. This macro-filter-lens design does not need additional macro lenses and it provides an inexpensive and optically good (aberration compensated) solution for macro imaging of objects not placed close to the camera.

  7. Exploring the depth range for three-dimensional laser machining with aberration correction.

    PubMed

    Salter, P S; Baum, M; Alexeev, I; Schmidt, M; Booth, M J

    2014-07-28

    The spherical aberration generated when focusing from air into another medium limits the depth at which ultrafast laser machining can be accurately maintained. We investigate how the depth range may be extended using aberration correction via a liquid crystal spatial light modulator (SLM), in both single point and parallel multi-point fabrication in fused silica. At a moderate numerical aperture (NA = 0.5), high fidelity fabrication with a significant level of parallelisation is demonstrated at the working distance of the objective lens, corresponding to a depth in the glass of 2.4 mm. With a higher numerical aperture (NA = 0.75) objective lens, single point fabrication is demonstrated to a depth of 1 mm utilising the full NA, and deeper with reduced NA, while maintaining high repeatability. We present a complementary theoretical model that enables prediction of the effectiveness of SLM based correction for different aberration magnitudes.

  8. Morphometric, quantitative, and three-dimensional analysis of the heart muscle fibers of old rats: transmission electron microscopy and high-resolution scanning electron microscopy methods.

    PubMed

    Cury, Diego Pulzatto; Dias, Fernando José; Sosthenes, Marcia Consentino Kronka; Dos Santos Haemmerle, Carlos Alexandre; Ogawa, Koichi; Da Silva, Marcelo Cavenaghi Pereira; Mardegan Issa, João Paulo; Iyomasa, Mamie Mizusaki; Watanabe, Ii-Sei

    2013-02-01

    This research investigated the morphological, morphometric, and ultrastructural cardiomyocyte characteristics of male Wistar rats at 18 months of age. The animals were euthanized using an overdose of anesthesia (ketamine and xylazine, 150/10 mg/kg) and perfused transcardially, after which samples were collected for light microscopy, transmission electron microscopy, and high-resolution scanning electron microscopy. The results showed that cardiomyocyte arrangement was disposed parallel between the mitochondria and the A-, I-, and H-bands and their M- and Z-lines from the sarcomere. The sarcomere junction areas had intercalated disks, a specific structure of heart muscle. The ultrastructural analysis revealed several mitochondria of various sizes and shapes intermingled between the blood capillaries and their endothelial cells; some red cells inside vessels are noted. The muscle cell sarcolemma could be observed associated with the described structures. The cardiomyocytes of old rats presented an average sarcomere length of 2.071 ± 0.09 μm, a mitochondrial volume density (Vv) of 0.3383, a mitochondrial average area of 0.537 ± 0.278 μm(2), a mitochondrial average length of 1.024 ± 0.352 μm, an average mitochondrial cristae thickness of 0.038 ± 0.09 μm and a ratio of mitochondrial greater length/lesser length of 1.929 ± 0.965. Of the observed mitochondrial shapes, 23.4% were rounded, 45.3% were elongated, and 31.1% had irregular profiles. In this study, we analyzed the morphology and morphometry of cardiomyocytes in old rats, focusing on mitochondria. These data are important for researchers who focus the changes in cardiac tissue, especially changes owing to pathologies and drug administration that may or may not be correlated with aging.

  9. Direct observation of atomic columns in a Bi-2223 polycrystal by aberration-corrected STEM using a low accelerating voltage

    NASA Astrophysics Data System (ADS)

    Nagai, Takuro; Haruta, Mitsutaka; Kikuchi, Masashi; Zhang, Weizhu; Takeguchi, Masaki; Kimoto, Koji

    2014-05-01

    Aberration correction in scanning transmission electron microscopy (STEM) enables an atomic-scale probe size of ˜0.1 nm at a low accelerating voltage of 80 kV that avoids knock-on damage in materials including light elements such as oxygen. We used this advanced method of microscopy to directly observe atomic columns in a (Bi,Pb)2Sr2Ca2Cu3O10+δ (Bi-2223) superconducting wire produced by a powder-in-tube method. Using the atomic-number (Z) contrast mechanism, incoherent high-angle annular dark-field (HAADF) imaging clearly showed the atomic columns. Atomic displacements toward the boundary with a maximum magnitude of ˜0.26 nm enable each atomic layer to be continuous at edge grain boundaries (EGBs). The grains tend to be terminated with deficient (Bi,Pb)-O single layers at c-axis twist boundaries (TWBs) and small-angle asymmetrical tilt boundaries (ATBs); a quantitative HAADF analysis showed that the occupancies of the (Bi,Pb) sites around these boundaries are ˜0.66 and ˜0.72, respectively. Electron energy-loss spectroscopy (EELS) mapping successfully visualized atomic columns in the half-unit cell intergrowth of (Bi,Pb)2Sr2CaCu2O8+δ (Bi-2212) and (Bi,Pb)2Sr2Ca3Cu4O12+δ (Bi-2234) phases. Furthermore, the HAADF analysis indicated that the occupancy of the (Bi,Pb) sites is modulated between ˜0.88 and 1.0 along the diagonal direction of the primitive perovskite cell with the same period as the structural modulation.

  10. High Resolution PDF Measurements on Ag Nanoparticles

    SciTech Connect

    Rocha, Tulio C. R.; Martin, Chris; Kycia, Stefan; Zanchet, Daniela

    2009-01-29

    The quantitative analysis of structural defects in Ag nanoparticles was addressed in this work. We performed atomic scale structural characterization by a combination of x-ray diffraction (XRD) using the Pair Distribution Function analysis (PDF) and High Resolution Transmission Electron Microscopy (HRTEM). The XRD measurements were performed using an innovative instrumentation setup to provide high resolution PDF patterns.

  11. An aberration-corrected STEM study of structural defects in epitaxial GaN thin films grown by ion beam assisted MBE.

    PubMed

    Poppitz, David; Lotnyk, Andriy; Gerlach, Jürgen W; Lenzner, Jörg; Grundmann, Marius; Rauschenbach, Bernd

    2015-06-01

    Ion-beam assisted molecular-beam epitaxy was used for direct growth of epitaxial GaN thin films on super-polished 6H-SiC(0001) substrates. The GaN films with different film thicknesses were studied using reflection high energy electron diffraction, X-ray diffraction, cathodoluminescence and primarily aberration-corrected scanning transmission electron microscopy techniques. Special attention was devoted to the microstructural characterization of GaN thin films and the GaN-SiC interface on the atomic scale. The results show a variety of defect types in the GaN thin films and at the GaN-SiC interface. A high crystalline quality of the produced hexagonal GaN thin films was demonstrated. The gained results are discussed.

  12. A high-resolution transmission electron microscopy study of interfaces between the γ, B2, and α2 phases in a Ti-Al-Mo alloy

    NASA Astrophysics Data System (ADS)

    Das, S.; Howe, J. M.; Perepezko, J. H.

    1996-06-01

    Conventional and high-resolution transmission electron microscopy (HRTEM) were used to examine the interfacial structures in a Ti-50Al-5Mo (at. pct) alloy which was processed to produce combinations of γ, B2, and α2 phases in a single sample. A small amount of a fourth phase labeled ζ was also found in the microstructure. It may be the phase Ti2AlN but confirmation requires analysis of the N content in the phase.In this alloy, the orientation relationship between the γ and B2 phases is {111}γ ∥}110}B2 and <101]γ ∥ <111>B2 with a coherent habit-plane interface parallel to (474)γ. The orientation relationship between the B2 and α2 (and also the ζ @#@) phases is {110}B2 ∥(0001)α2/ζ and <111>B2 ∥<11-20>α2/ζ with a coherent interface parallel to the close-packed planes and along other orientations. The orientation relationship between the α2 (and also the ζ @#@) and γ phases is (0001)α2/ζ ∥{lll}γ and (11•20)α2/ζ ∥<10•1]γ. The α2 phase has a coherent interface parallel to the close-packed planes, while the ζ phase appears to adopt the (474)γ interface plane of the γ phase, similar to the B2 phase. In some cases, the interface configuration between the γ and B2 phases appears to be altered by the presence of α2 phase, resulting in a semicoherent interface. The phase labeled ζ in this study has the same orientation relationship with the γ and B2 phases as α2 but consists of an ABABAC... stacking of close-packed basal planes. The (474)γ habit plane interface between the γ and B2 phases is analyzed by several different theories of interfacial structure, and microstructural evolution in this system is also discussed.

  13. High Resolution STEM-EELS Study of Silver Nanoparticles Exposed to Light and Humic Substances.

    PubMed

    Römer, Isabella; Wang, Zhi Wei; Merrifield, Ruth C; Palmer, Richard E; Lead, Jamie

    2016-03-01

    Nanoparticles (NPs) are defined as particles with at least one dimension between 1 and 100 nm or with properties that differ from their bulk material, which possess unique properties. The extensive use of NPs means that discharge to the environment is likely increasing, but fate, behavior, and effects under environmentally relevant conditions are insufficiently studied. This paper focuses on the transformations of silver nanoparticles (AgNPs) under simulated but realistic environmental conditions. High resolution aberration-corrected scanning transmission electron microscopy (HAADF STEM) coupled with electron energy loss spectroscopy (EELS) and UV-vis were used within a multimethod approach to study morphology, surface chemistry transformations, and corona formation. Although loss, most likely by dissolution, was observed, there was no direct evidence of oxidation from the STEM-EELS. However, in the presence of fulvic acid (FA), a 1.3 nm oxygen-containing corona was observed around the AgNPs in water; modeled data based on the HAADF signal at near atomic resolution suggest this was an FA corona was formed and was not silver oxide, which was coherent (i.e., fully coated in FA), where observed. The corona further colloidally stabilized the NPs for periods of weeks to months, dependent on the solution conditions. PMID:26792384

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Chromatic-aberration-corrected diffractive lenses for ultra-broadband focusing

    DOE PAGES

    Wang, Peng; Mohammad, Nabil; Menon, Rajesh

    2016-02-12

    We exploit the inherent dispersion in diffractive optics to demonstrate planar chromatic-aberration-corrected lenses. Specifically, we designed, fabricated and characterized cylindrical diffractive lenses that efficiently focus the entire visible band (450 nm to 700 nm) onto a single line. These devices are essentially pixelated, multi-level microstructures. Experiments confirm an average optical efficiency of 25% for a three-wavelength apochromatic lens whose chromatic focus shift is only 1.3 μm and 25 μm in the lateral and axial directions, respectively. Super-achromatic performance over the continuous visible band is also demonstrated with averaged lateral and axial focus shifts of only 1.65 μm and 73.6 μm,more » respectively. These lenses are easy to fabricate using single-step grayscale lithography and can be inexpensively replicated. Furthermore, these devices are thin (<3 μm), error tolerant, has low aspect ratio (<1:1) and offer polarization-insensitive focusing, all significant advantages compared to alternatives that rely on metasurfaces. Lastly, our design methodology offers high design flexibility in numerical aperture and focal length, and is readily extended to 2D.« less

  16. Chromatic-aberration-corrected diffractive lenses for ultra-broadband focusing

    PubMed Central

    Wang, Peng; Mohammad, Nabil; Menon, Rajesh

    2016-01-01

    We exploit the inherent dispersion in diffractive optics to demonstrate planar chromatic-aberration-corrected lenses. Specifically, we designed, fabricated and characterized cylindrical diffractive lenses that efficiently focus the entire visible band (450 nm to 700 nm) onto a single line. These devices are essentially pixelated, multi-level microstructures. Experiments confirm an average optical efficiency of 25% for a three-wavelength apochromatic lens whose chromatic focus shift is only 1.3 μm and 25 μm in the lateral and axial directions, respectively. Super-achromatic performance over the continuous visible band is also demonstrated with averaged lateral and axial focus shifts of only 1.65 μm and 73.6 μm, respectively. These lenses are easy to fabricate using single-step grayscale lithography and can be inexpensively replicated. Furthermore, these devices are thin (<3 μm), error tolerant, has low aspect ratio (<1:1) and offer polarization-insensitive focusing, all significant advantages compared to alternatives that rely on metasurfaces. Our design methodology offers high design flexibility in numerical aperture and focal length, and is readily extended to 2D. PMID:26868264

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

    NASA Astrophysics Data System (ADS)

    Hsiao, Chien-Nan; Kuo, Shou-Yi; Lai, Fang-I.; Chen, Wei-Chun

    2014-10-01

    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.

  18. Large-Volume Reconstruction of Brain Tissue from High-Resolution Serial Section Images Acquired by SEM-Based Scanning Transmission Electron Microscopy

    PubMed Central

    Kuwajima, Masaaki; Mendenhall, John M.; Harris, Kristen M.

    2013-01-01

    With recent improvements in instrumentation and computational tools, serial section electron microscopy has become increasingly straightforward. A new method for imaging ultrathin serial sections is developed based on a field emission scanning electron microscope fitted with a transmitted electron detector. This method is capable of automatically acquiring high-resolution serial images with a large field size and very little optical and physical distortions. In this chapter, we describe the procedures leading to the generation and analyses of a large-volume stack of high-resolution images (64 μm × 64 μm × 10 μm, or larger, at 2 nm pixel size), including how to obtain large-area serial sections of uniform thickness from well-preserved brain tissue that is rapidly perfusion-fixed with mixed aldehydes, processed with a microwave-enhanced method, and embedded into epoxy resin. PMID:23086880

  19. Large-volume reconstruction of brain tissue from high-resolution serial section images acquired by SEM-based scanning transmission electron microscopy.

    PubMed

    Kuwajima, Masaaki; Mendenhall, John M; Harris, Kristen M

    2013-01-01

    With recent improvements in instrumentation and computational tools, serial section electron microscopy has become increasingly straightforward. A new method for imaging ultrathin serial sections is developed based on a field emission scanning electron microscope fitted with a transmitted electron detector. This method is capable of automatically acquiring high-resolution serial images with a large field size and very little optical and physical distortions. In this chapter, we describe the procedures leading to the generation and analyses of a large-volume stack of high-resolution images (64 μm × 64 μm × 10 μm, or larger, at 2 nm pixel size), including how to obtain large-area serial sections of uniform thickness from well-preserved brain tissue that is rapidly perfusion-fixed with mixed aldehydes, processed with a microwave-enhanced method, and embedded into epoxy resin.

  20. Electron dose dependence of signal-to-noise ratio, atom contrast and resolution in transmission electron microscope images.

    PubMed

    Lee, Z; Rose, H; Lehtinen, O; Biskupek, J; Kaiser, U

    2014-10-01

    In order to achieve the highest resolution in aberration-corrected (AC) high-resolution transmission electron microscopy (HRTEM) images, high electron doses are required which only a few samples can withstand. In this paper we perform dose-dependent AC-HRTEM image calculations, and study the dependence of the signal-to-noise ratio, atom contrast and resolution on electron dose and sampling. We introduce dose-dependent contrast, which can be used to evaluate the visibility of objects under different dose conditions. Based on our calculations, we determine optimum samplings for high and low electron dose imaging conditions.

  1. Electron dose dependence of signal-to-noise ratio, atom contrast and resolution in transmission electron microscope images.

    PubMed

    Lee, Z; Rose, H; Lehtinen, O; Biskupek, J; Kaiser, U

    2014-10-01

    In order to achieve the highest resolution in aberration-corrected (AC) high-resolution transmission electron microscopy (HRTEM) images, high electron doses are required which only a few samples can withstand. In this paper we perform dose-dependent AC-HRTEM image calculations, and study the dependence of the signal-to-noise ratio, atom contrast and resolution on electron dose and sampling. We introduce dose-dependent contrast, which can be used to evaluate the visibility of objects under different dose conditions. Based on our calculations, we determine optimum samplings for high and low electron dose imaging conditions. PMID:24566042

  2. High resolution multimodal clinical ophthalmic imaging system.

    PubMed

    Mujat, Mircea; Ferguson, R Daniel; Patel, Ankit H; Iftimia, Nicusor; Lue, Niyom; Hammer, Daniel X

    2010-05-24

    We developed a multimodal adaptive optics (AO) retinal imager which is the first to combine high performance AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. Such systems are becoming ever more essential to vision research and are expected to prove their clinical value for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa. The SSOCT channel operates at a wavelength of 1 microm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. This AO system is designed for use in clinical populations; a dual deformable mirror (DM) configuration allows simultaneous low- and high-order aberration correction over a large range of refractions and ocular media quality. The system also includes a wide field (33 deg.) line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation, an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of lateral eye motion, and a high-resolution LCD-based fixation target for presentation of visual cues. The system was tested in human subjects without retinal disease for performance optimization and validation. We were able to resolve and quantify cone photoreceptors across the macula to within approximately 0.5 deg (approximately 100-150 microm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve features deep into the choroid. The prototype presented here is the first of a new class of powerful flexible imaging platforms that will provide clinicians and researchers with high-resolution, high performance adaptive optics imaging to help guide therapies, develop new drugs, and improve patient outcomes.

  3. Aberration correction during real time in vivo imaging of bone marrow with sensorless adaptive optics confocal microscope

    NASA Astrophysics Data System (ADS)

    Wang, Zhibin; Wei, Dan; Wei, Ling; He, Yi; Shi, Guohua; Wei, Xunbin; Zhang, Yudong

    2014-08-01

    We have demonstrated adaptive correction of specimen-induced aberration during in vivo imaging of mouse bone marrow vasculature with confocal fluorescence microscopy. Adaptive optics system was completed with wavefront sensorless correction scheme based on stochastic parallel gradient descent algorithm. Using image sharpness as the optimization metric, aberration correction was performed based upon Zernike polynomial modes. The experimental results revealed the improved signal and resolution leading to a substantially enhanced image contrast with aberration correction. The image quality of vessels at 38- and 75-μm depth increased three times and two times, respectively. The corrections allowed us to detect clearer bone marrow vasculature structures at greater contrast and improve the signal-to-noise ratio.

  4. A method to determine fault vectors in 4H-SiC from stacking sequences observed on high resolution transmission electron microscopy images

    SciTech Connect

    Wu, Fangzhen; Wang, Huanhuan; Raghothamachar, Balaji; Dudley, Michael; Mueller, Stephan G.; Chung, Gil; Sanchez, Edward K.; Hansen, Darren; Loboda, Mark J.; Zhang, Lihua; Su, Dong; Kisslinger, Kim; Stach, Eric

    2014-09-14

    A new method has been developed to determine the fault vectors associated with stacking faults in 4H-SiC from their stacking sequences observed on high resolution TEM images. This method, analogous to the Burgers circuit technique for determination of dislocation Burgers vector, involves determination of the vectors required in the projection of the perfect lattice to correct the deviated path constructed in the faulted material. Results for several different stacking faults were compared with fault vectors determined from X-ray topographic contrast analysis and were found to be consistent. This technique is expected to applicable to all structures comprising corner shared tetrahedra.

  5. High-resolution headlamp

    NASA Astrophysics Data System (ADS)

    Gut, Carsten; Cristea, Iulia; Neumann, Cornelius

    2016-04-01

    The following article shall describe how human vision by night can be influenced. At first, front lighting systems that are already available on the market will be described, followed by their analysis with respect to the positive effects on traffic safety. Furthermore, how traffic safety by night can be increased since the introduction of high resolution headlamps shall be discussed.

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

    PubMed Central

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

    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 to 83y 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 logMAR 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 cataract surgery resulted in very low residual higher order aberration (HOA) and normal straylight. PMID:26309872

  7. Energy-based adaptive focusing of waves: application to noninvasive aberration correction of ultrasonic wavefields

    PubMed Central

    Herbert, Eric; Pernot, Mathieu; Montaldo, Gabriel; Fink, Mathias; Tanter, Mickael

    2009-01-01

    An aberration correction method based on the maximization of the wave intensity at the focus of an emitting array is presented. The potential of this new adaptive focusing technique is investigated for ultrasonic focusing in biological tissues. The acoustic intensity is maximized non invasively through the direct measurement or indirect estimation of the beam energy at the focus for a series of spatially coded emissions. For ultrasonic waves, the acoustic energy at the desired focus can be indirectly estimated from the local displacements induced in tissues by the ultrasonic radiation force of the beam. Based on the measurement of these displacements, this method allows the precise estimation of the phase and amplitude aberrations and consequently the correction of aberrations along the beam travel path. The proof of concept is first performed experimentally using a large therapeutic array with strong electronic phase aberrations (up to 2π). Displacements induced by the ultrasonic radiation force at the desired focus are indirectly estimated using the time shift of backscattered echoes recorded on the array. The phase estimation is deduced accurately using a direct inversion algorithm which reduces the standard deviation of the phase distribution from σ = 1.89 before correction to σ = 0.53 following correction. The corrected beam focusing quality is verified using a needle hydrophone. The peak intensity obtained through the aberrator is found to be −7.69 dB below the reference intensity obtained without any aberration. Using the phase correction, a sharp focus is restored through the aberrator with a relative peak intensity of −0.89 dB. The technique is tested experimentally using a linear transmit/receive array through a real aberrating layer. The array is used to automatically correct its beam quality, as it both generates the radiation force with coded excitations and indirectly estimates the acoustic intensity at the focus with speckle tracking. This

  8. High-resolution transmission electron microscopy study on the growth modes of GaSb islands grown on a semi-insulating GaAs (001) substrate

    NASA Astrophysics Data System (ADS)

    Kim, Y. H.; Lee, J. Y.; Noh, Y. G.; Kim, M. D.; Oh, J. E.

    2007-06-01

    The initial growth behaviors of GaSb on a GaAs substrate were studied using a high-resolution electron microscope (HRTEM). Four types of GaSb islands were observed by HRTEM. HRTEM micrographs showed that strain relaxation mechanisms were different in the four types of islands. Although 90° misfit dislocations relieve misfit strain in the islands, additional mechanisms are required to relax the remaining strain. The existence of elastic deformation near the surface related to dislocations and intermediate layers between GaSb and GaAs were demonstrated in island growths. Finally, the generation of planar defects to relieve strain was observed in a specific GaSb growth.

  9. High resolution data acquisition

    DOEpatents

    Thornton, Glenn W.; Fuller, Kenneth R.

    1993-01-01

    A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock (38) pulse train (37) and analog circuitry (44) for generating a triangular wave (46) synchronously with the pulse train (37). The triangular wave (46) has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter (18, 32) forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter (26) counts the clock pulse train (37) during the interval to form a gross event interval time. A computer (52) then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.

  10. High resolution data acquisition

    DOEpatents

    Thornton, G.W.; Fuller, K.R.

    1993-04-06

    A high resolution event interval timing system measures short time intervals such as occur in high energy physics or laser ranging. Timing is provided from a clock, pulse train, and analog circuitry for generating a triangular wave synchronously with the pulse train (as seen in diagram on patent). The triangular wave has an amplitude and slope functionally related to the time elapsed during each clock pulse in the train. A converter forms a first digital value of the amplitude and slope of the triangle wave at the start of the event interval and a second digital value of the amplitude and slope of the triangle wave at the end of the event interval. A counter counts the clock pulse train during the interval to form a gross event interval time. A computer then combines the gross event interval time and the first and second digital values to output a high resolution value for the event interval.

  11. High-Resolution Autoradiography

    NASA Technical Reports Server (NTRS)

    Towe, George C; Gomberg, Henry J; Freemen, J W

    1955-01-01

    This investigation was made to adapt wet-process autoradiography to metallurgical samples to obtain high resolution of segregated radioactive elements in microstructures. Results are confined to development of the technique, which was perfected to a resolution of less than 10 microns. The radioactive samples included carbon-14 carburized iron and steel, nickel-63 electroplated samples, a powder product containing nickel-63, and tungsten-185 in N-155 alloy.

  12. Ultra high resolution tomography

    SciTech Connect

    Haddad, W.S.

    1994-11-15

    Recent work and results on ultra high resolution three dimensional imaging with soft x-rays will be presented. This work is aimed at determining microscopic three dimensional structure of biological and material specimens. Three dimensional reconstructed images of a microscopic test object will be presented; the reconstruction has a resolution on the order of 1000 A in all three dimensions. Preliminary work with biological samples will also be shown, and the experimental and numerical methods used will be discussed.

  13. CONDENSED MATTER: STRUCTURE, THERMAL AND MECHANICAL PROPERTIES: High-resolution transmission electron microscopy and bulk magnetometry study of LaFe11.5Si1.5 compound

    NASA Astrophysics Data System (ADS)

    Zou, Jun-Ding; Li, Wei; Shen, Bao-Gen

    2009-10-01

    This paper studies the microstructural and magnetic properties of LaFe11.5Si1.5 compound by means of high-resolution transmission electron microscope and bulk magnetometry measurements. The crystalline structure is accompanied with the noncrystalline and nanocrystalline structures. This characteristic is the reflection of the crystalline process held by quenching. The inverse susceptibilities diverge and deviate from Curie-Weiss law under low applied magnetic fields. This paper proposes the possible mechanism between the anomalous susceptibilities and microstructure, and offers a perspective on the magnetic properties of metastable intermetallic compounds.

  14. The extraction of gold nanoparticles from oat and wheat biomasses using sodium citrate and cetyltrimethylammonium bromide, studied by x-ray absorption spectroscopy, high-resolution transmission electron microscopy, and UV-visible spectroscopy.

    PubMed

    Armendariz, Veronica; Parsons, Jason G; Lopez, Martha L; Peralta-Videa, Jose R; Jose-Yacaman, Miguel; Gardea-Torresdey, Jorge L

    2009-03-11

    Gold (Au) nanoparticles can be produced through the interaction of Au(III) ions with oat and wheat biomasses. This paper describes a procedure to recover gold nanoparticles from oat and wheat biomasses using cetyltrimethylammonium bromide or sodium citrate. Extracts were analyzed using UV-visible spectroscopy, high-resolution transmission electron microscopy (HRTEM), and x-ray absorption spectroscopy. The HRTEM data demonstrated that smaller nanoparticles are extracted first, followed by larger nanoparticles. In the fourth extraction, coating of chelating agents is visible on the extracted nanoparticles.

  15. The extraction of gold nanoparticles from oat and wheat biomasses using sodium citrate and cetyltrimethylammonium bromide, studied by x-ray absorption spectroscopy, high-resolution transmission electron microscopy, and UV-visible spectroscopy

    NASA Astrophysics Data System (ADS)

    Armendariz, Veronica; Parsons, Jason G.; Lopez, Martha L.; Peralta-Videa, Jose R.; Jose-Yacaman, Miguel; Gardea-Torresdey, Jorge L.

    2009-03-01

    Gold (Au) nanoparticles can be produced through the interaction of Au(III) ions with oat and wheat biomasses. This paper describes a procedure to recover gold nanoparticles from oat and wheat biomasses using cetyltrimethylammonium bromide or sodium citrate. Extracts were analyzed using UV-visible spectroscopy, high-resolution transmission electron microscopy (HRTEM), and x-ray absorption spectroscopy. The HRTEM data demonstrated that smaller nanoparticles are extracted first, followed by larger nanoparticles. In the fourth extraction, coating of chelating agents is visible on the extracted nanoparticles.

  16. Transmission electron microscopy: Visualizing fullerene chemistry

    NASA Astrophysics Data System (ADS)

    Terrones, Mauricio

    2010-02-01

    Chemical reactions of fullerenes and metallofullerenes lined up inside single-walled carbon nanotubes can be monitored at the atomic scale inside an aberration-corrected transmission electron microscope.

  17. Triosmium clusters on a support: determination of structure by X-ray absorption spectroscopy and high-resolution microscopy.

    PubMed

    Mehraeen, Shareghe; Kulkarni, Apoorva; Chi, Miaofang; Reed, Bryan W; Okamoto, Norihiko L; Browning, Nigel D; Gates, Bruce C

    2011-01-17

    The structures of small, robust metal clusters on a solid support were determined by a combination of spectroscopic and microscopic methods: extended X-ray absorption fine structure (EXAFS) spectroscopy, scanning transmission electron microscopy (STEM), and aberration-corrected STEM. The samples were synthesized from [Os(3) (CO)(12) ] on MgO powder to provide supported clusters intended to be triosmium. The results demonstrate that the supported clusters are robust in the absence of oxidants. Conventional high-angle annular dark-field (HAADF) STEM images demonstrate a high degree of uniformity of the clusters, with root-mean-square (rms) radii of 2.03±0.06 Å. The EXAFS OsOs coordination number of 2.1±0.4 confirms the presence of triosmium clusters on average and correspondingly determines an average rms cluster radius of 2.02±0.04 Å. The high-resolution STEM images show the individual Os atoms in the clusters, confirming the triangular structures of their frames and determining OsOs distances of 2.80±0.14 Å, matching the EXAFS value of 2.89±0.06 Å. IR and EXAFS spectra demonstrate the presence of CO ligands on the clusters. This set of techniques is recommended as optimal for detailed and reliable structural characterization of supported clusters. PMID:21226118

  18. Triosmium Clusters on a Support: Determination of Structure by X-Ray Absorption Spectroscopy and High-Resolution Microscopy

    SciTech Connect

    Shareghe, Mehraeen; Chi, Miaofang; Browning, Nigel D.

    2011-01-01

    The structures of small, robust metal clusters on a solid support were determined by a combination of spectroscopic and microscopic methods: extended X-ray absorption fine structure (EXAFS) spectroscopy, scanning transmission electron microscopy (STEM), and aberration-corrected STEM. The samples were synthesized from [Os{sub 3}(CO){sub 12}] on MgO powder to provide supported clusters intended to be triosmium. The results demonstrate that the supported clusters are robust in the absence of oxidants. Conventional high-angle annular dark-field (HAADF) STEM images demonstrate a high degree of uniformity of the clusters, with root-mean-square (rms) radii of 2.03 {+-} 0.06 {angstrom}. The EXAFS OsOs coordination number of 2.1 {+-} 0.4 confirms the presence of triosmium clusters on average and correspondingly determines an average rms cluster radius of 2.02 {+-} 0.04 {angstrom}. The high-resolution STEM images show the individual Os atoms in the clusters, confirming the triangular structures of their frames and determining OsOs distances of 2.80 {+-} 0.14 {angstrom}, matching the EXAFS value of 2.89 {+-} 0.06 {angstrom}. IR and EXAFS spectra demonstrate the presence of CO ligands on the clusters. This set of techniques is recommended as optimal for detailed and reliable structural characterization of supported clusters.

  19. Observation of the atomic structure of ß'-SiAlON using three generations of high resolution electron microscopes

    NASA Astrophysics Data System (ADS)

    Thorel, A.; Ciston, J.; Bartel, T.; Song, C.-Y.; Dahmen, U.

    2013-04-01

    The structure of a ß‧-SiAlON (Si5.6Al0.4O0.4N7.6) has been observed using three generations of unique high resolution microscopes spanning over three decades of development in instrumentation - the Atomic Resolution Microscope (ARM), the One Angstrom Microscope (OAM) and the Transmission Electron Aberration-corrected Microscope (TEAM). The information limits of these microscopes are 0.16, 0.08 and 0.05 nm respectively. Observations along ⟨0 0 0 1⟩ at Scherzer defocus for each microscope demonstrate a drastic increase in structural information. Images taken on TEAM show clearly resolved atomic columns whereas the ARM images were only indirectly related to the structure. Nevertheless, the loss of the six-fold symmetry associated with the O/N and Al/Si substitutions was already visible on images taken on the ARM, and an associated ∼25 pm displacement of the O substituting for N in some of the 2c Wyckoff positions of the SiN unit cell was measured on exit wave reconstructions obtained from through focal series on the OAM. This paper illustrates how progress in instrumentation impacts our analysis and understanding of materials.

  20. On the benefit of aberration-corrected HAADF-STEM for strain determination and its application to tailoring ferroelectric domain patterns.

    PubMed

    Tang, Y L; Zhu, Y L; Ma, X L

    2016-01-01

    Revealing strains on the unit-cell level is essential for understanding the particular performance of materials. Large-scale strain variations with a unit-cell resolution are important for studying ferroelectric materials since the spontaneous polarizations of such materials are strongly coupled with strains. Aberration-corrected high-angle-annular-dark-field scanning transmission electron microscopy (AC-HAADF-STEM) is not so sensitive to the sample thickness and therefore thickness gradients. Consequently it is extremely useful for large-scale strain determination, which can be readily extracted by geometrical phase analysis (GPA). Such a combination has various advantages: it is straightforward, accurate on the unit-cell scale, relatively insensitive to crystal orientation and therefore helpful for large-scale. We take a tetragonal ferroelectric PbTiO3 film as an example in which large-scale strains are determined. Furthermore, based on the specific relationship between lattice rotation and spontaneous polarization (Ps) at 180° domain-walls, the Ps directions are identified, which makes the investigation of ferroelectric domain structures accurate and straightforward. This method is proposed to be suitable for investigating strain-related phenomena in other ferroelectric materials.

  1. Computed Ultrasound Tomography in Echo mode (CUTE) of speed of sound for diagnosis and for aberration correction in pulse-echo sonography

    NASA Astrophysics Data System (ADS)

    Jaeger, Michael; Held, Gerrit; Preisser, Stefan; Peeters, Sara; Grünig, Michael; Frenz, Martin

    2014-03-01

    Sound speed as a diagnostic marker for various diseases of human tissue has been of interest for a while. Up to now, mostly transmission ultrasound computed tomography (UCT) was able to detect spatially resolved sound speed, and its promise as a diagnostic tool has been demonstrated. However, UCT is limited to acoustically transparent samples such as the breast. We present a novel technique where spatially resolved detection of sound speed can be achieved using conventional pulse-echo equipment in reflection mode. For this purpose, pulse-echo images are acquired under various transmit beam directions and a two-dimensional map of the sound speed is reconstructed from the changing phase of local echoes using a direct reconstruction method. Phantom results demonstrate that a high spatial resolution (1 mm) and contrast (0.5 % of average sound speed) can be achieved suitable for diagnostic purposes. In comparison to previous reflection-mode based methods, CUTE works also in a situation with only diffuse echoes, and its direct reconstruction algorithm enables real-time application. This makes it suitable as an addition to conventional clinical ultrasound where it has the potential to benefit diagnosis in a multimodal approach. In addition, knowledge of the spatial distribution of sound speed allows full aberration correction and thus improved spatial resolution and contrast of conventional B-mode ultrasound.

  2. Atomic-resolution study of dislocation structures and interfaces in poly-crystalline thin film CdTe using aberration-corrected STEM

    NASA Astrophysics Data System (ADS)

    Paulauskas, Tadas; Colegrove, Eric; Buurma, Chris; Kim, Moon; Klie, Robert

    2014-03-01

    Commercial success of CdTe-based thin film photovoltaic devices stems from its nearly ideal direct band gap which very effectively couples to Sun's light spectrum as well as ease of manufacturing and low cost of these modules. However, to further improve the conversion efficiency beyond 20 percent, it is important to minimize the harmful effects of grain boundaries and lattice defects in CdTe. Direct atomic-scale characterization is needed in order identify the carrier recombination centers. Likewise, it is necessary to confirm that passivants in CdTe, such as Cl, are able to diffuse and bind to the target defects. In this study, we characterize dislocation structures and grain boundaries in poly-crystalline CdTe using aberration-corrected cold-field emission scanning transmission electron microscopy (STEM). The chemical composition of Shockley partial, Frank and Lomer-Cottrell dislocations is examined via atomic column-resolved X-ray energy dispersive (XEDS) and electron energy-loss spectroscopies (EELS). Segregation of Cl towards dislocation cores and grain boundaries is shown in CdCl2 treated samples. We also investigate interfaces in ultra-high-vacuum bonded CdTe bi-crystals with pre-defined misorientation angles which are intended to mimic grain boundaries. Funded by: DOE EERE Sunshot Award EE0005956.

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

    SciTech Connect

    Han, Chang W.; Iddir, Hakim; Uzun, Alper; Curtiss, Larry A.; Browning, Nigel D.; Gates, Bruce C.; Ortalan, Volkan

    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.

  4. Aberration-corrected X-ray spectrum imaging and Fresnel contrast to differentiate nanoclusters and cavities in helium-irradiated alloy 14YWT

    SciTech Connect

    Miller, Michael K; Parish, Chad M

    2014-01-01

    Helium accumulation negatively impacts structural materials used in neutron-irradiated environments, such as fission and fusion reactors. Next-generation fission and fusion reactors will require structural materials, such as steels, resistant to large neutron doses yet see service temperatures in the range most affected by helium embrittlement. Previous work has indicated the difficulty of experimentally differentiating nanometer-sized helium bubbles from the Ti-Y-O rich nanoclustsers (NCs) in radiation-tolerant nanostructured ferritic alloys (NFAs). Because the NCs are expected to sequester helium away from grain boundaries and reduce embrittlement, experimental methods to study simultaneously the NC and bubble populations are needed. In this study, aberration-corrected scanning transmission electron microscopy (STEM) results combining high-collection-efficiency X-ray spectrum images (SIs), multivariate statistical analysis (MVSA), and Fresnel-contrast bright-field STEM imaging have been used for such a purpose. Results indicate that Fresnel-contrast imaging, with careful attention to TEM-STEM reciprocity, differentiates bubbles from NCs, and MVSA of X-ray SIs unambiguously identifies NCs. Therefore, combined Fresnel-contrast STEM and X-ray SI is an effective STEM-based method to characterize helium-bearing NFAs.

  5. Atomic resolution imaging of graphene by transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Robertson, Alex W.; Warner, Jamie H.

    2013-05-01

    The atomic structure of a material influences its electronic, chemical, magnetic and mechanical properties. Characterising carbon nanomaterials, such as fullerenes, nanotubes and graphene, at the atomic level is challenging due to their chemical reactivity and low atomic mass. Transmission electron microscopy and scanning probe microscopy are two of the leading methods for imaging graphene at the atomic level. Here, we report on recent advances in atomic resolution imaging of graphene using aberration-corrected high resolution transmission electron microscopy and how it has revealed many of the structural deviations from the pristine monolayer form. Structures in graphene such as vacancy defects, edges, grain boundaries, linear chains, impurity dopants, layer number, layer stacking and bond rotations are explored.

  6. Nanoscale Three-Dimensional Microstructural Characterization of an Sn-Rich Solder Alloy Using High-Resolution Transmission X-Ray Microscopy (TXM).

    PubMed

    Kaira, Chandrashekara S; Mayer, Carl R; De Andrade, V; De Carlo, Francesco; Chawla, Nikhilesh

    2016-08-01

    Three-dimensional (3D) nondestructive microstructural characterization was performed using full-field transmission X-ray microscopy on an Sn-rich alloy, at a spatial resolution of 60 nm. This study highlights the use of synchrotron radiation along with Fresnel zone plate optics to perform absorption contrast tomography for analyzing nanoscale features of fine second phase particles distributed in the tin matrix, which are representative of the bulk microstructure. The 3D reconstruction was also used to quantify microstructural details of the analyzed volume. PMID:27426439

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

    SciTech Connect

    Hettrick, M.C.; Underwood, J.H.

    1986-10-01

    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 (lambda/..delta..lambda > 10/sup 4/) monochromator or scanning spectrometer with a simple rotational motion for scanning wavelength or selecting the spectral band. 21 refs., 4 figs.

  8. High-resolution chemical analysis on cycled LiFePO4 battery electrodes using energy-filtered transmission electron microscopy

    NASA Astrophysics Data System (ADS)

    Sugar, Joshua D.; El Gabaly, Farid; Chueh, William C.; Fenton, Kyle R.; Tyliszczak, Tolek; Kotula, Paul G.; Bartelt, Norman C.

    2014-01-01

    We demonstrate an ex situ method for analyzing the chemistry of battery electrode particles after electrochemical cycling using the transmission electron microscope (TEM). The arrangement of particles during our analysis is the same as when the particles are being cycled. We start by sectioning LiFePO4 battery electrodes using an ultramicrotome. We then show that mapping of the Fe2+ and Fe3+ oxidation state using energy-filtered TEM (EFTEM) and multivariate statistical analysis techniques can be used to determine the spatial distribution of Li in the particles. This approach is validated by comparison with scanning transmission X-ray microscopy (STXM) analysis of the same samples [Chueh et al. Nanoletters, 13 (3) (2013) 866-72]. EFTEM uses a parallel electron beam and reduces the electron-beam dose (and potential beam-induced damage) to the sample when compared to alternate techniques that use a focused probe (e.g. STEM-EELS). Our analysis confirms that under the charging conditions of the analyzed battery, mixed phase particles are rare and thus Li intercalation is limited by the nucleation of new phases.

  9. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study.

    PubMed

    Jones, Ryan M; O'Reilly, Meaghan A; Hynynen, Kullervo

    2013-07-21

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337-43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source's emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system's resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring techniques currently exist.

  10. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    PubMed Central

    Jones, Ryan M.; O’Reilly, Meaghan A.; Hynynen, Kullervo

    2013-01-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337–43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring technique currently exists. PMID:23807573

  11. Transcranial passive acoustic mapping with hemispherical sparse arrays using CT-based skull-specific aberration corrections: a simulation study

    NASA Astrophysics Data System (ADS)

    Jones, Ryan M.; O'Reilly, Meaghan A.; Hynynen, Kullervo

    2013-07-01

    The feasibility of transcranial passive acoustic mapping with hemispherical sparse arrays (30 cm diameter, 16 to 1372 elements, 2.48 mm receiver diameter) using CT-based aberration corrections was investigated via numerical simulations. A multi-layered ray acoustic transcranial ultrasound propagation model based on CT-derived skull morphology was developed. By incorporating skull-specific aberration corrections into a conventional passive beamforming algorithm (Norton and Won 2000 IEEE Trans. Geosci. Remote Sens. 38 1337-43), simulated acoustic source fields representing the emissions from acoustically-stimulated microbubbles were spatially mapped through three digitized human skulls, with the transskull reconstructions closely matching the water-path control images. Image quality was quantified based on main lobe beamwidths, peak sidelobe ratio, and image signal-to-noise ratio. The effects on the resulting image quality of the source’s emission frequency and location within the skull cavity, the array sparsity and element configuration, the receiver element sensitivity, and the specific skull morphology were all investigated. The system’s resolution capabilities were also estimated for various degrees of array sparsity. Passive imaging of acoustic sources through an intact skull was shown possible with sparse hemispherical imaging arrays. This technique may be useful for the monitoring and control of transcranial focused ultrasound (FUS) treatments, particularly non-thermal, cavitation-mediated applications such as FUS-induced blood-brain barrier disruption or sonothrombolysis, for which no real-time monitoring techniques currently exist.

  12. Synergistic enhancements of ultrasound image contrast with a combination of phase aberration correction and dual apodization with cross-correlation.

    PubMed

    Shin, Junseob; Yen, Jesse T

    2012-09-01

    Dual apodization with cross-correlation (DAX) is a novel adaptive beamforming technique which utilizes two distinct apodization functions in suppressing side lobes and clutter. Previous studies have shown that the performance of DAX in minimizing the effects of phase aberration diminishes with increasing aberrator strength. To achieve greater improvement in image contrast, we propose, in this paper, to combine DAX with a phase aberration correction algorithm based on nearest-neighbor cross-correlation (NNCC). Our simulation and experimental results presented in this work showed that the proposed method allows for synergistic enhancements of image contrast and achieves greater improvement in image quality than using DAX alone or phase aberration correction alone in the presence of weak and strong aberrators. Compared with standard delay-and-sum (DAS) beamforming, using the proposed method on simulated data with weak and strong aberrations increased the contrast-to-noise ratio (CNR) values from 4.10 to 10.96 and from 1.69 to 9.80, respectively. Experimental results were obtained using pork tissues of 4 and 10 mm thickness and a tissue-mimicking phantom. The CNR values increased from 3.74 to 9.72 for the 4-mm pork aberrator and from 1.27 to 8.17 for the 10-mm pork aberrator. PMID:23007784

  13. High-resolution three-dimensional scanning transmission electron microscopy characterization of oxide-nitride-oxide layer interfaces in Si-based semiconductors using computed tomography.

    PubMed

    Sadayama, Shoji; Sekiguchi, Hiromi; Bright, Alexander; Suzuki, Naohisa; Yamada, Kazuhiro; Kaneko, Kenji

    2011-01-01

    Oxide-nitride-oxide (ONO) layer structures are widely used for charge storage in flash memory devices. The ONO layer interfaces should be as flat as possible, so measurement of the nanoscale roughness of those interfaces is needed. In this study, quantification of an ONO film from a commercially available flash memory device was carried out with a pillar-shaped specimen using scanning transmission electron microscopy (STEM) and computed tomography. The ONO area contained only low Z- and low STEM-contrast materials, which makes high-quality reconstruction difficult. The optimum three-dimensional reconstruction was achieved with an STEM annular dark-field detector inner collection angle of 32 mrad, a sample tilt range from -78° to +78° and 25 iterations for the simultaneous iterative reconstruction technique.

  14. High-resolution genetic analysis of the requirements for horizontal transmission of the ESBL plasmid from Escherichia coli O104:H4

    PubMed Central

    Yamaichi, Yoshiharu; Chao, Michael C.; Sasabe, Jumpei; Clark, Lars; Davis, Brigid M.; Yamamoto, Nozomi; Mori, Hiroshi; Kurokawa, Ken; Waldor, Matthew K.

    2015-01-01

    Horizontal dissemination of the genes encoding extended spectrum beta-lactamases (ESBLs) via conjugative plasmids is facilitating the increasingly widespread resistance of pathogens to beta-lactam antibiotics. However, there is relatively little known about the regulatory factors and mechanisms that govern the spread of these plasmids. Here, we carried out a high-throughput, transposon insertion site sequencing analysis (TnSeq) to identify genes that enable the maintenance and transmission of pESBL, an R64 (IncI1)-related resistance plasmid that was isolated from Escherichia coli O104:H4 linked to a recent large outbreak of gastroenteritis. With a few exceptions, the majority of the genes identified as required for maintenance and transmission of pESBL matched those of their previously defined R64 counterparts. However, our analyses of the high-density transposon insertion library in pESBL also revealed two very short and linked regions that constitute a previously unrecognized regulatory system controlling spread of IncI1 plasmids. In addition, we investigated the function of the pESBL-encoded M.EcoGIX methyltransferase, which is also encoded by many other IncI1 and IncF plasmids. This enzyme proved to protect pESBL from restriction in new hosts, suggesting it aids in expanding the plasmid's host range. Collectively, our work illustrates the power of the TnSeq approach to enable rapid and comprehensive analyses of plasmid genes and sequences that facilitate the dissemination of determinants of antibiotic resistance. PMID:25477379

  15. High Resolution Laboratory Spectroscopy

    NASA Astrophysics Data System (ADS)

    Brünken, S.; Schlemmer, S.

    2016-05-01

    In this short review we will highlight some of the recent advancements in the field of high-resolution laboratory spectroscopy that meet the needs dictated by the advent of highly sensitive and broadband telescopes like ALMA and SOFIA. Among these is the development of broadband techniques for the study of complex organic molecules, like fast scanning conventional absorption spectroscopy based on multiplier chains, chirped pulse instrumentation, or the use of synchrotron facilities. Of similar importance is the extension of the accessible frequency range to THz frequencies, where many light hydrides have their ground state rotational transitions. Another key experimental challenge is the production of sufficiently high number densities of refractory and transient species in the laboratory, where discharges have proven to be efficient sources that can also be coupled to molecular jets. For ionic molecular species sensitive action spectroscopic schemes have recently been developed to overcome some of the limitations of conventional absorption spectroscopy. Throughout this review examples demonstrating the strong interplay between laboratory and observational studies will be given.

  16. High Resolution Doppler Imager

    NASA Technical Reports Server (NTRS)

    Hays, Paul B.

    1999-01-01

    This report summarizes the accomplishments of the High Resolution Doppler Imager (HRDI) on UARS spacecraft during the period 4/l/96 - 3/31/99. During this period, HRDI operation, data processing, and data analysis continued, and there was a high level of vitality in the HRDI project. The HRDI has been collecting data from the stratosphere, mesosphere, and lower thermosphere since instrument activation on October 1, 1991. The HRDI team has stressed three areas since operations commenced: 1) operation of the instrument in a manner which maximizes the quality and versatility of the collected data; 2) algorithm development and validation to produce a high-quality data product; and 3) scientific studies, primarily of the dynamics of the middle atmosphere. There has been no significant degradation in the HRDI instrument since operations began nearly 8 years ago. HRDI operations are fairly routine, although we have continued to look for ways to improve the quality of the scientific product, either by improving existing modes, or by designing new ones. The HRDI instrument has been programmed to collect data for new scientific studies, such as measurements of fluorescence from plants, measuring cloud top heights, and lower atmosphere H2O.

  17. Periodic cation segregation in Cs0.44[Nb2.54W2.46O14] quantified by high-resolution scanning transmission electron microscopy.

    PubMed

    Heidelmann, Markus; Barthel, Juri; Cox, Gerhard; Weirich, Thomas E

    2014-10-01

    The atomic structure of Cs0.44[Nb2.54W2.46O14] closely resembles the structure of the most active catalyst for the synthesis of acrylic acid, the M1 phase of Mo10V2(4+)Nb2TeO42-x. Consistently with observations made for the latter compound, the high-angle electron scattering signal recorded by scanning transmission electron microscopy shows a significant intensity variation, which repeats periodically with the projected crystallographic unit cell. The occupation factors for the individual mixed Nb/W atomic columns are extracted from the observed intensity variations. For this purpose, experimental images and simulated images are compared on an identical intensity scale, which enables a quantification of the cation distribution. According to our analysis specific sites possess low tungsten concentrations of 25%, whereas other sites have tungsten concentrations above 70%. These findings allow us to refine the existing structure model of the target compound, which has until now described a uniform distribution of the niobium and tungsten atoms in the unit cell, showing that the similarity between Cs0.44[Nb2.54W2.46O14] and the related catalytic compounds also extends to the level of the cation segregation.

  18. Component analyses of urinary nanocrystallites of uric acid stone formers by combination of high-resolution transmission electron microscopy, fast Fourier transformation, energy dispersive X-ray spectroscopy, X-ray diffraction and Fourier transform infrared spectroscopy.

    PubMed

    Sun, Xin-Yuan; Xue, Jun-Fa; Xia, Zhi-Yue; Ouyang, Jian-Ming

    2015-06-01

    This study aimed to analyse the components of nanocrystallites in urines of patients with uric acid (UA) stones. X-ray diffraction (XRD), Fourier transform infrared spectroscopy, high-resolution transmission electron microscopy (HRTEM), fast Fourier transformation (FFT) of HRTEM, and energy dispersive X-ray spectroscopy (EDS) were performed to analyse the components of these nanocrystallites. XRD and FFT showed that the main component of urinary nanocrystallites was UA, which contains a small amount of calcium oxalate monohydrate and phosphates. EDS showed the characteristic absorption peaks of C, O, Ca and P. The formation of UA stones was closely related to a large number of UA nanocrystallites in urine. A combination of HRTEM, FFT, EDS and XRD analyses could be performed accurately to analyse the components of urinary nanocrystallites.

  19. Evidence for anisotropic dielectric properties of monoclinic hafnia using valence electron energy-loss spectroscopy in high-resolution transmission electron microscopy and ab initio time-dependent density-functional theory

    SciTech Connect

    Guedj, C.; Hung, L.; Sottile, F.; Zobelli, A.; Blaise, P.; Olevano, V.

    2014-12-01

    The effect of nanocrystal orientation on the energy loss spectra of monoclinic hafnia (m-HfO{sub 2}) is measured by high resolution transmission electron microscopy (HRTEM) and valence energy loss spectroscopy (VEELS) on high quality samples. For the same momentum-transfer directions, the dielectric properties are also calculated ab initio by time-dependent density-functional theory (TDDFT). Experiments and simulations evidence anisotropy in the dielectric properties of m-HfO{sub 2}, most notably with the direction-dependent oscillator strength of the main bulk plasmon. The anisotropic nature of m-HfO{sub 2} may contribute to the differences among VEELS spectra reported in literature. The good agreement between the complex dielectric permittivity extracted from VEELS with nanometer spatial resolution, TDDFT modeling, and past literature demonstrates that the present HRTEM-VEELS device-oriented methodology is a possible solution to the difficult nanocharacterization challenges given in the International Technology Roadmap for Semiconductors.

  20. High-resolution differentiation of transmissible spongiform encephalopathy strains by quantitative N-terminal amino acid profiling (N-TAAP) of PK-digested abnormal prion protein.

    PubMed

    Gielbert, Adriana; Davis, Linda A; Sayers, A Robin; Hope, James; Gill, Andrew C; Sauer, Maurice J

    2009-03-01

    New forms of transmissible spongiform encephalopathy (TSE) continue to be identified, and consequently sensitive differential diagnosis is increasingly important both for the management of disease in humans and livestock and in providing confidence in the safety of the food chain. TSE diseases are associated with accumulation of protease-resistant prion protein (PrP(Sc)) and detection of this marker protein is central to diagnosis. Proteolysis by proteinase K (PK) generates protease-resistant products (PrP(res)) with partially variable N-termini. The conformation(s) of PrP(Sc) and thus the points of PK cleavage are thought to be dependent on the strain of prion disease. Western blot (WB) analysis of PrP(res) gives characteristic migration patterns that can be used to diagnose TSEs, but the relatively low resolution of this technique limits its ability to differentiate certain disease strains. Mass spectrometry (MS) has the capability to resolve these various PK cleavage sites to the level of individual amino acid residues. In the present study multiple selected reaction monitoring (mSRM) was used to detect and quantify PrP(res) N-terminal tryptic peptides by MS and thus to define the N-terminal amino acid profiles (N-TAAPs) of PrP(res) characteristic for various TSEs in sheep. The fragmentation behaviour of the N-terminal tryptic peptides was studied to allow selection of the transitions specific for each peptide. Different PrP(res) preparation methods were evaluated and the most effective approach applied to differentiate the N-TAAPs corresponding to various sheep TSE isolates. Marked differences were identified between the N-TAAPs of bovine spongiform encephalopathy (BSE) and classical scrapie, and between classical scrapie and the experimental strains SSBP/1 and CH1641, thereby validating this approach as a means of TSE-strain specific diagnosis.

  1. Anisotropic aberration correction using region of interest based digital adaptive optics in Fourier domain OCT.

    PubMed

    Kumar, Abhishek; Kamali, Tschackad; Platzer, René; Unterhuber, Angelika; Drexler, Wolfgang; Leitgeb, Rainer A

    2015-04-01

    In this paper a numerical technique is presented to compensate for anisotropic optical aberrations, which are usually present across the lateral field of view in the out of focus regions, in high resolution optical coherence tomography and microscopy (OCT/OCM) setups. The recorded enface image field at different depths in the tomogram is digitally divided into smaller sub-regions or the regions of interest (ROIs), processed individually using subaperture based digital adaptive optics (DAO), and finally stitched together to yield a final image with a uniform diffraction limited resolution across the entire field of view (FOV). Using this method, a sub-micron lateral resolution is achieved over a depth range of 218 [Formula: see text]for a nano-particle phantom sample imaged using a fiber based point scanning spectral domain (SD) OCM system with a limited depth of focus (DOF) of ~7 [Formula: see text]at a numerical aperture (NA) of 0.6. Thus, an increase in DOF by ~30x is demonstrated in this case. The application of this method is also shown in ex vivo mouse adipose tissue.

  2. Anisotropic aberration correction using region of interest based digital adaptive optics in Fourier domain OCT

    PubMed Central

    Kumar, Abhishek; Kamali, Tschackad; Platzer, René; Unterhuber, Angelika; Drexler, Wolfgang; Leitgeb, Rainer A.

    2015-01-01

    In this paper a numerical technique is presented to compensate for anisotropic optical aberrations, which are usually present across the lateral field of view in the out of focus regions, in high resolution optical coherence tomography and microscopy (OCT/OCM) setups. The recorded enface image field at different depths in the tomogram is digitally divided into smaller sub-regions or the regions of interest (ROIs), processed individually using subaperture based digital adaptive optics (DAO), and finally stitched together to yield a final image with a uniform diffraction limited resolution across the entire field of view (FOV). Using this method, a sub-micron lateral resolution is achieved over a depth range of 218 μmfor a nano-particle phantom sample imaged using a fiber based point scanning spectral domain (SD) OCM system with a limited depth of focus (DOF) of ~7 μmat a numerical aperture (NA) of 0.6. Thus, an increase in DOF by ~30x is demonstrated in this case. The application of this method is also shown in ex vivo mouse adipose tissue. PMID:25908999

  3. Imaging nanometre-scale structure in cells using in situ aberration correction.

    PubMed

    Fuller, C J; Straight, A F

    2012-10-01

    Accurate distance measurements of cellular structures on a length scale relevant to single macromolecules or macromolecular complexes present a major challenge for biological microscopy. In addition to the inherent challenges of overcoming the limits imposed by the diffraction of light, cells themselves are a complex and poorly understood optical environment. We present an extension of the high-resolution colocalization method to measure three dimensional distances between diffraction-limited objects using standard widefield fluorescence microscopy. We use this method to demonstrate that in three dimensions, cells intrinsically introduce a large and variable amount of chromatic aberration into optical measurements. We present a means of correcting this aberration in situ [termed 'Colocalization and In-situ Correction of Aberration for Distance Analysis' (CICADA)] by exploiting the fact that there is a linear relationship between the degree of aberration between different wavelengths. By labelling a cellular structure with redundantly multi-colour labelled antibodies, we can create an intracellular fiducial marker for correcting the individual aberrations between two different wavelengths in the same cells. Our observations demonstrate that with suitable corrections, nanometre scale three-dimensional distance measurements can be used to probe the substructure of macromolecular complexes within cells.

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

    NASA Astrophysics Data System (ADS)

    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

  5. High Resolution Formaldehyde Photochemistry

    NASA Astrophysics Data System (ADS)

    Ernest, C. T.; Bauer, D.; Hynes, A. J.

    2010-12-01

    Formaldehyde (HCHO) is the most abundant and most important organic carbonyl compound in the atmosphere. The sources of formaldehyde are the oxidation of methane, isoprene, acetone, and other volatile organic compounds (VOCs); fossil fuel combustion; and biomass burning. The dominant loss mechanism for formaldehyde is photolysis which occurs via two pathways: (R1) HCHO + hv → HCO + H (R2) HCHO + hv → H2 + CO The first pathway (R1) is referred to as the radical channel, while the second pathway (R2) is referred to as the molecular channel. The products of both pathways play a significant role in atmospheric chemistry. The CO that is produced in the molecular channel undergoes further oxidation to produce CO2. Under atmospheric conditions, the H atom and formyl radical that are produced in the radical channel undergo rapid reactions with O2 to produce the hydroperoxyl radical (HO2) via (R3) and (R4). (R3) HCO + O2 → HO2 + CO (R4) H + O2 → HO2 Thus, for every photon absorbed, the photolysis of formaldehyde can contribute one CO2 molecule to the global greenhouse budget or two HO2 radicals to the tropospheric HOx (OH + HO2) cycle. The HO2 radicals produced during formaldehyde photolysis have also been implicated in the formation of photochemical smog. The HO2 radicals act as radical chain carriers and convert NO to NO2, which ultimately results in the catalytic production of O3. Constraining the yield of HO2 produced via HCHO photolysis is essential for improving tropospheric chemistry models. In this study, both the absorption cross section and the quantum yield of the radical channel (R1) were measured at high resolution over the tropospherically relevant wavelength range 304-330 nm. For the cross section measurements a narrow linewidth Nd:YAG pumped dye laser was used with a multi-pass cell. Partial pressures of HCHO were kept below 0.3 torr. Simultaneous measurement of OH LIF in a flame allowed absolute calibration of the wavelength scale. Pressure

  6. Progress on PEEM3 - An Aberration Corrected X-Ray PhotoemissionElectron Microscope at the ALS

    SciTech Connect

    MacDowell, Alastair A.; Feng, J.; DeMello, A.; Doran, A.; Duarte,R.; Forest, E.; Kelez, N.; Marcus, M.A.; Miller, T.; Padmore, H.A.; Raoux, S.; Robin, D.; Scholl, A.; Schlueter, R.; Schmid, P.; Stohr, J.; Wan, W.; Wei, D.H.; Wu, Y.

    2006-05-20

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

  7. Bayesian-based aberration correction and numerical diffraction for improved lensfree on-chip microscopy of biological specimens.

    PubMed

    Wong, Alexander; Kazemzadeh, Farnoud; Jin, Chao; Wang, Xiao Yu

    2015-05-15

    Lensfree on-chip microscopy is an emerging imaging technique that can be used to visualize and study biological specimens without the need for imaging lens systems. Important issues that can limit the performance of lensfree on-chip microscopy include interferometric aberrations, acquisition noise, and image reconstruction artifacts. In this study, we introduce a Bayesian-based method for performing aberration correction and numerical diffraction that accounts for all three of these issues to improve the effective numerical aperture (NA) and signal-to-noise ratio (SNR) of the reconstructed microscopic image. The proposed method was experimentally validated using the USAF resolution target as well as real waterborne Anabaena flos-aquae samples, demonstrating improvements in NA by ∼25% over the standard method, and improvements in SNR of 2.8 and 8.2 dB in the reconstructed image when compared to the reconstructed images produced using the standard method and a maximum likelihood estimation method, respectively.

  8. High resolution time interval meter

    DOEpatents

    Martin, A.D.

    1986-05-09

    Method and apparatus are provided for measuring the time interval between two events to a higher resolution than reliability available from conventional circuits and component. An internal clock pulse is provided at a frequency compatible with conventional component operating frequencies for reliable operation. Lumped constant delay circuits are provided for generating outputs at delay intervals corresponding to the desired high resolution. An initiation START pulse is input to generate first high resolution data. A termination STOP pulse is input to generate second high resolution data. Internal counters count at the low frequency internal clock pulse rate between the START and STOP pulses. The first and second high resolution data are logically combined to directly provide high resolution data to one counter and correct the count in the low resolution counter to obtain a high resolution time interval measurement.

  9. High resolution optoelectronic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Loudin, Jim; Dinyari, Rostam; Huie, Phil; Butterwick, Alex; Peumans, Peter; Palanker, Daniel

    2009-02-01

    Electronic retinal prostheses seek to restore sight in patients with retinal degeneration by delivering pulsed electric currents to retinal neurons via an array of microelectrodes. Most implants use inductive or optical transmission of information and power to an intraocular receiver, with decoded signals subsequently distributed to retinal electrodes through an intraocular cable. Surgical complexity could be minimized by an "integrated" prosthesis, in which both power and data are delivered directly to the stimulating array without any discrete components or cables. We present here an integrated retinal prosthesis system based on a photodiode array implant. Video frames are processed and imaged onto the retinal implant by a video goggle projection system operating at near-infrared wavelengths (~ 900 nm). Photodiodes convert light into pulsed electric current, with charge injection maximized by specially optimized series photodiode circuits. Prostheses of three different pixel densities (16 pix/mm2, 64 pix/mm2, and 256 pix/mm2) have been designed, simulated, and prototyped. Retinal tissue response to subretinal implants made of various materials has been investigated in RCS rats. The resulting prosthesis can provide sufficient charge injection for high resolution retinal stimulation without the need for implantation of any bulky discrete elements such as coils or tethers. In addition, since every pixel functions independently, pixel arrays may be placed separately in the subretinal space, providing visual stimulation to a larger field of view.

  10. High resolution transmission electron microscopy of aluminophosphates

    SciTech Connect

    Ulan, J.G.; Gronsky, R. ); Szostak, R. ); Sorby, K. . Dept. of Chemistry)

    1990-04-01

    VPI-5 transforms to AlPO{sub 4}-8 under mild thermal treatment (100{degree}C, 18 hrs). HRTEM micrographs, oriented normal to the c axis, show extensive defect-free regions in VPI-5, while slip planes normal to the c axis are found in AlPO{sub 4}-8. Analysis of the HRTEM data, in conjunction with infrared and thermal analysis, adsorption studies and x-ray powder diffraction, has lead to a proposed structure for AlPO{sub 4}-8. Though the sheets containing the 18 member rings which define the pores in VPI-5 remain intact in AlPO{sub 4}-8, reduction in the porosity is attributed to blockages created by the movement of these sheets relative to each other. 8 refs., 7 figs.

  11. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV.

    PubMed

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-12

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed C_{c}/C_{s} corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations. PMID:27563976

  12. Chromatic Aberration Correction for Atomic Resolution TEM Imaging from 20 to 80 kV

    NASA Astrophysics Data System (ADS)

    Linck, Martin; Hartel, Peter; Uhlemann, Stephan; Kahl, Frank; Müller, Heiko; Zach, Joachim; Haider, Max.; Niestadt, Marcel; Bischoff, Maarten; Biskupek, Johannes; Lee, Zhongbo; Lehnert, Tibor; Börrnert, Felix; Rose, Harald; Kaiser, Ute

    2016-08-01

    Atomic resolution in transmission electron microscopy of thin and light-atom materials requires a rigorous reduction of the beam energy to reduce knockon damage. However, at the same time, the chromatic aberration deteriorates the resolution of the TEM image dramatically. Within the framework of the SALVE project, we introduce a newly developed Cc/Cs corrector that is capable of correcting both the chromatic and the spherical aberration in the range of accelerating voltages from 20 to 80 kV. The corrector allows correcting axial aberrations up to fifth order as well as the dominating off-axial aberrations. Over the entire voltage range, optimum phase-contrast imaging conditions for weak signals from light atoms can be adjusted for an optical aperture of at least 55 mrad. The information transfer within this aperture is no longer limited by chromatic aberrations. We demonstrate the performance of the microscope using the examples of 30 kV phase-contrast TEM images of graphene and molybdenum disulfide, showing unprecedented contrast and resolution that matches image calculations.

  13. Linking environmental processes to the in situ functioning of microorganisms by high-resolution secondary ion mass spectrometry (NanoSIMS) and scanning transmission X-ray microscopy (STXM).

    PubMed

    Behrens, Sebastian; Kappler, Andreas; Obst, Martin

    2012-11-01

    Environmental microbiology research increasingly focuses on the single microbial cell as the defining entity that drives environmental processes. The interactions of individual microbial cells with each other, the environment and with higher organisms shape microbial communities and control the functioning of whole ecosystems. A single-cell view of microorganisms in their natural environment requires analytical tools that measure both cell function and chemical speciation at the submicrometre scale. Here we review the technical capabilities and limitations of high-resolution secondary ion mass spectrometry (NanoSIMS) and scanning transmission (soft) X-ray microscopy (STXM) and give examples of their applications. Whereas NanoSIMS can be combined with isotope-labelling, thereby localizing the distribution of cellular activities (e.g. carbon/nitrogen fixation/turnover), STXM provides information on the location and chemical speciation of metabolites and products of redox reactions. We propose the combined use of both techniques and discuss the technical challenges of their joint application. Both techniques have the potential to enhance our understanding of cellular mechanisms and activities that contribute to microbially mediated processes, such as the biogeochemical cycling of elements, the transformation of contaminants and the precipitation of mineral phases.

  14. Electron diffraction and high-resolution transmission electron microscopy of the high temperature crystal structures of GexSb2Te3+x (x=1,2,3) phase change material

    NASA Astrophysics Data System (ADS)

    Kooi, B. J.; De Hosson, J. Th. M.

    2002-10-01

    The crystal structures of GeSb2Te4, Ge2Sb2Te5, and Ge3Sb2Te6 were determined using electron diffraction and high-resolution transmission electron microscopy. The structure determined for the former two crystals deviates from the ones proposed in the literature. These crystal structures were developed jointly upon cooling of liquid Ge2Sb2Te5. A stacking disorder parallel to the basal plane was observed that increases with increasing cooling rates. For the GexSb2Te3+x (x=1,2,3) crystals it is shown that an a,b,c stacking holds with an alternating stacking of x GeTe double layers identically present in binary GeTe and one Te-Sb-Te-Te-Sb- repeat unit also present in binary Sb2Te3. A stacking disorder is a logical consequence of building crystals with these two principal units. On the other hand, it is likely that all stable crystals of the Ge-Sb-Te systems are an ordered sequence of these two units. Some of the implications of these findings of the stable and metastable crystal structures that develop from amorphous Ge2Sb2Te5 are presented so as to understand the crucial crystallization process in Ge2Sb2Te5 phase change material.

  15. Dynamic Aberration Correction for Conformal Window of High-Speed Aircraft Using Optimized Model-Based Wavefront Sensorless Adaptive Optics.

    PubMed

    Dong, Bing; Li, Yan; Han, Xin-Li; Hu, Bin

    2016-09-02

    For high-speed aircraft, a conformal window is used to optimize the aerodynamic performance. However, the local shape of the conformal window leads to large amounts of dynamic aberrations varying with look angle. In this paper, deformable mirror (DM) and model-based wavefront sensorless adaptive optics (WSLAO) are used for dynamic aberration correction of an infrared remote sensor equipped with a conformal window and scanning mirror. In model-based WSLAO, aberration is captured using Lukosz mode, and we use the low spatial frequency content of the image spectral density as the metric function. Simulations show that aberrations induced by the conformal window are dominated by some low-order Lukosz modes. To optimize the dynamic correction, we can only correct dominant Lukosz modes and the image size can be minimized to reduce the time required to compute the metric function. In our experiment, a 37-channel DM is used to mimic the dynamic aberration of conformal window with scanning rate of 10 degrees per second. A 52-channel DM is used for correction. For a 128 × 128 image, the mean value of image sharpness during dynamic correction is 1.436 × 10(-5) in optimized correction and is 1.427 × 10(-5) in un-optimized correction. We also demonstrated that model-based WSLAO can achieve convergence two times faster than traditional stochastic parallel gradient descent (SPGD) method.

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

    NASA Astrophysics Data System (ADS)

    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 <= 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 Brønsted acid sites highly active for the low temperature process. The results open up opportunities for developing green heterogeneous methods for pharmaceuticals.

  17. Dynamic Aberration Correction for Conformal Window of High-Speed Aircraft Using Optimized Model-Based Wavefront Sensorless Adaptive Optics.

    PubMed

    Dong, Bing; Li, Yan; Han, Xin-Li; Hu, Bin

    2016-01-01

    For high-speed aircraft, a conformal window is used to optimize the aerodynamic performance. However, the local shape of the conformal window leads to large amounts of dynamic aberrations varying with look angle. In this paper, deformable mirror (DM) and model-based wavefront sensorless adaptive optics (WSLAO) are used for dynamic aberration correction of an infrared remote sensor equipped with a conformal window and scanning mirror. In model-based WSLAO, aberration is captured using Lukosz mode, and we use the low spatial frequency content of the image spectral density as the metric function. Simulations show that aberrations induced by the conformal window are dominated by some low-order Lukosz modes. To optimize the dynamic correction, we can only correct dominant Lukosz modes and the image size can be minimized to reduce the time required to compute the metric function. In our experiment, a 37-channel DM is used to mimic the dynamic aberration of conformal window with scanning rate of 10 degrees per second. A 52-channel DM is used for correction. For a 128 × 128 image, the mean value of image sharpness during dynamic correction is 1.436 × 10(-5) in optimized correction and is 1.427 × 10(-5) in un-optimized correction. We also demonstrated that model-based WSLAO can achieve convergence two times faster than traditional stochastic parallel gradient descent (SPGD) method. PMID:27598161

  18. Dynamic Aberration Correction for Conformal Window of High-Speed Aircraft Using Optimized Model-Based Wavefront Sensorless Adaptive Optics

    PubMed Central

    Dong, Bing; Li, Yan; Han, Xin-li; Hu, Bin

    2016-01-01

    For high-speed aircraft, a conformal window is used to optimize the aerodynamic performance. However, the local shape of the conformal window leads to large amounts of dynamic aberrations varying with look angle. In this paper, deformable mirror (DM) and model-based wavefront sensorless adaptive optics (WSLAO) are used for dynamic aberration correction of an infrared remote sensor equipped with a conformal window and scanning mirror. In model-based WSLAO, aberration is captured using Lukosz mode, and we use the low spatial frequency content of the image spectral density as the metric function. Simulations show that aberrations induced by the conformal window are dominated by some low-order Lukosz modes. To optimize the dynamic correction, we can only correct dominant Lukosz modes and the image size can be minimized to reduce the time required to compute the metric function. In our experiment, a 37-channel DM is used to mimic the dynamic aberration of conformal window with scanning rate of 10 degrees per second. A 52-channel DM is used for correction. For a 128 × 128 image, the mean value of image sharpness during dynamic correction is 1.436 × 10−5 in optimized correction and is 1.427 × 10−5 in un-optimized correction. We also demonstrated that model-based WSLAO can achieve convergence two times faster than traditional stochastic parallel gradient descent (SPGD) method. PMID:27598161

  19. New design studies for TRIUMF's ARIEL High Resolution Separator

    NASA Astrophysics Data System (ADS)

    Maloney, J. A.; Baartman, R.; Marchetto, M.

    2016-06-01

    As part of its new Advanced Rare IsotopE Laboratory (ARIEL), TRIUMF is designing a novel High Resolution Separator (HRS) (Maloney et al., 2015) to separate rare isotopes. The HRS has a 180° bend, separated into two 90° magnetic dipoles, bend radius 1.2 m, with an electrostatic multipole corrector between them. Second order correction comes mainly from the dipole edge curvatures, but is intended to be fine-tuned with a sextupole component and a small octupole component in the multipole. This combination is designed to achieve 1:20,000 resolution for a 3 μm (horizontal) and 6 μm (vertical) emittance. A design for the HRS dipole magnets achieves both radial and integral flatness goals of <10-5. A review of the optical design for the HRS is presented, including the study of limiting factors affecting separation, matching and aberration correction. Field simulations from the OPERA-3D (OPERA) [2] models of the dipole magnets are used in COSY Infinity (COSY) (Berz and Makino, 2005) [3] to find and optimize the transfer maps to 3rd order and study residual nonlinearities to 8th order.

  20. Insights into complexation of dissolved organic matter and Al(III) and nanominerals formation in soils under contrasting fertilizations using two-dimensional correlation spectroscopy and high resolution-transmission electron microscopy techniques.

    PubMed

    Wen, Yongli; Li, Huan; Xiao, Jian; Wang, Chang; Shen, Qirong; Ran, Wei; He, Xinhua; Zhou, Quansuo; Yu, Guanghui

    2014-09-01

    Understanding the organomineral associations in soils is of great importance. Using two-dimensional correlation spectroscopy (2DCOS) and high resolution-transmission electron microscopy (HRTEM) techniques, this study compared the binding characteristics of organic ligands to Al(III) in dissolved organic matter (DOM) from soils under short-term (3-years) and long-term (22-years) fertilizations. Three fertilization treatments were examined: (i) no fertilization (Control), (ii) chemical nitrogen, phosphorus and potassium (NPK), and (iii) NPK plus swine manure (NPKM). Soil spectra detected by the 2DCOS Fourier transform infrared (FTIR) spectroscopy showed that fertilization modified the binding characteristics of organic ligands to Al(III) in soil DOM at both short- and long- term location sites. The CH deformations in aliphatic groups played an important role in binding to Al(III) but with minor differences among the Control, NPK and NPKM at the short-term site. While at the long-term site both C-O stretching of polysaccharides or polysaccharide-like substances and aliphatic O-H were bound to Al(III) under the Control, whereas only aliphatic O-H, and only polysaccharides and silicates, were bound to Al(III) under NPK and NPKM, respectively. Images from HRTEM demonstrated that crystalline nanominerals, composed of Fe and O, were predominant in soil DOM under NPK, while amorphous nanominerals, predominant in Al, Si, and O, were dominant in soil DOM under Control and NPKM. In conclusion, fertilization strategies, especially under long-term, could affect the binding of organic ligands to Al(III) in soil DOM, which resulted in alterations in the turnover, reactivity, and bioavailability of soil organic matter. Our results demonstrated that the FTIR-2DCOS combined with HRTEM techniques could enhance our understanding in the binding characteristics of DOM to Al(III) and the resulted nanominerals in soils.

  1. Insights into complexation of dissolved organic matter and Al(III) and nanominerals formation in soils under contrasting fertilizations using two-dimensional correlation spectroscopy and high resolution-transmission electron microscopy techniques.

    PubMed

    Wen, Yongli; Li, Huan; Xiao, Jian; Wang, Chang; Shen, Qirong; Ran, Wei; He, Xinhua; Zhou, Quansuo; Yu, Guanghui

    2014-09-01

    Understanding the organomineral associations in soils is of great importance. Using two-dimensional correlation spectroscopy (2DCOS) and high resolution-transmission electron microscopy (HRTEM) techniques, this study compared the binding characteristics of organic ligands to Al(III) in dissolved organic matter (DOM) from soils under short-term (3-years) and long-term (22-years) fertilizations. Three fertilization treatments were examined: (i) no fertilization (Control), (ii) chemical nitrogen, phosphorus and potassium (NPK), and (iii) NPK plus swine manure (NPKM). Soil spectra detected by the 2DCOS Fourier transform infrared (FTIR) spectroscopy showed that fertilization modified the binding characteristics of organic ligands to Al(III) in soil DOM at both short- and long- term location sites. The CH deformations in aliphatic groups played an important role in binding to Al(III) but with minor differences among the Control, NPK and NPKM at the short-term site. While at the long-term site both C-O stretching of polysaccharides or polysaccharide-like substances and aliphatic O-H were bound to Al(III) under the Control, whereas only aliphatic O-H, and only polysaccharides and silicates, were bound to Al(III) under NPK and NPKM, respectively. Images from HRTEM demonstrated that crystalline nanominerals, composed of Fe and O, were predominant in soil DOM under NPK, while amorphous nanominerals, predominant in Al, Si, and O, were dominant in soil DOM under Control and NPKM. In conclusion, fertilization strategies, especially under long-term, could affect the binding of organic ligands to Al(III) in soil DOM, which resulted in alterations in the turnover, reactivity, and bioavailability of soil organic matter. Our results demonstrated that the FTIR-2DCOS combined with HRTEM techniques could enhance our understanding in the binding characteristics of DOM to Al(III) and the resulted nanominerals in soils. PMID:24997950

  2. Identification of magnetic properties of few nm sized FePt crystalline particles by characterizing the intrinsic atom order using aberration corrected S/TEM.

    PubMed

    Biskupek, Johannes; Jinschek, Joerg R; Wiedwald, Ulf; Bendele, Markus; Han, Luyang; Ziemann, Paul; Kaiser, Ute

    2010-06-01

    Hard-magnetic nanomaterials like nanoparticles of FePt are of great interest because of their promising potential for data storage applications. The magnetic properties of FePt structures strongly differ whether the crystal phases are face centered cubic (fcc) or face centered tetragonal (fct). We evaluated aberration corrected HRTEM, electron diffraction and aberration corrected HAADF-STEM as methods to measure the chemical degree of order S that describes the ordering of Pt and Fe atoms within the crystals unit cells. S/TEM experiments are accompanied by image calculations. The findings are compared with results obtained from X-ray diffraction on a FePt film. Our results show that STEM is a reasonable fast approach over HRTEM and electron diffraction to locally determine the chemical degree of order S.

  3. ANL high-resolution injector

    SciTech Connect

    Minehara, E.; Kutschera, W.; Hartog, P.D.; Billquist, P.; Liu, Z.

    1986-05-01

    The ANL (Argonne National Laboratory) high-resolution injector has been installed to obtain higher mass resolution and higher preacceleration, and to utilize effectively the full mass range of ATLAS (Argonne tandem linac accelerator system). Preliminary results of the first beam test are reported briefly. The design and performance, in particular a high-mass-resolution magnet with aberration compensation, are discussed.

  4. High resolution digital delay timer

    DOEpatents

    Martin, Albert D.

    1988-01-01

    Method and apparatus are provided for generating an output pulse following a trigger pulse at a time delay interval preset with a resolution which is high relative to a low resolution available from supplied clock pulses. A first lumped constant delay (20) provides a first output signal (24) at predetermined interpolation intervals corresponding to the desired high resolution time interval. Latching circuits (26, 28) latch the high resolution data (24) to form a first synchronizing data set (60). A selected time interval has been preset to internal counters (142, 146, 154) and corrected for circuit propagation delay times having the same order of magnitude as the desired high resolution. Internal system clock pulses (32, 34) count down the counters to generate an internal pulse delayed by an interval which is functionally related to the preset time interval. A second LCD (184) corrects the internal signal with the high resolution time delay. A second internal pulse is then applied to a third LCD (74) to generate a second set of synchronizing data (76) which is complementary with the first set of synchronizing data (60) for presentation to logic circuits (64). The logic circuits (64) further delay the internal output signal (72) to obtain a proper phase relationship of an output signal (80) with the internal pulses (32, 34). The final delayed output signal (80) thereafter enables the output pulse generator (82) to produce the desired output pulse (84) at the preset time delay interval following input of the trigger pulse (10, 12).

  5. Advanced very high resolution radiometer

    NASA Technical Reports Server (NTRS)

    1976-01-01

    The advanced very high resolution radiometer development program is considered. The program covered the design, construction, and test of a breadboard model, engineering model, protoflight model, mechanical structural model, and a life test model. Special bench test and calibration equipment was also developed for use on the program.

  6. Experimental demonstration of passive acoustic imaging in the human skull cavity using CT-based aberration corrections

    PubMed Central

    Jones, Ryan M.; O’Reilly, Meaghan A.; Hynynen, Kullervo

    2015-01-01

    Purpose: Experimentally verify a previously described technique for performing passive acoustic imaging through an intact human skull using noninvasive, computed tomography (CT)-based aberration corrections Jones et al. [Phys. Med. Biol. 58, 4981–5005 (2013)]. Methods: A sparse hemispherical receiver array (30 cm diameter) consisting of 128 piezoceramic discs (2.5 mm diameter, 612 kHz center frequency) was used to passively listen through ex vivo human skullcaps (n = 4) to acoustic emissions from a narrow-band fixed source (1 mm diameter, 516 kHz center frequency) and from ultrasound-stimulated (5 cycle bursts, 1 Hz pulse repetition frequency, estimated in situ peak negative pressure 0.11–0.33 MPa, 306 kHz driving frequency) Definity™ microbubbles flowing through a thin-walled tube phantom. Initial in vivo feasibility testing of the method was performed. The performance of the method was assessed through comparisons to images generated without skull corrections, with invasive source-based corrections, and with water-path control images. Results: For source locations at least 25 mm from the inner skull surface, the modified reconstruction algorithm successfully restored a single focus within the skull cavity at a location within 1.25 mm from the true position of the narrow-band source. The results obtained from imaging single bubbles are in good agreement with numerical simulations of point source emitters and the authors’ previous experimental measurements using source-based skull corrections O’Reilly et al. [IEEE Trans. Biomed. Eng. 61, 1285–1294 (2014)]. In a rat model, microbubble activity was mapped through an intact human skull at pressure levels below and above the threshold for focused ultrasound-induced blood–brain barrier opening. During bursts that led to coherent bubble activity, the location of maximum intensity in images generated with CT-based skull corrections was found to deviate by less than 1 mm, on average, from the position

  7. Transformation of nanodiamond into carbon onions: A comparative study by high-resolution transmission electron microscopy, electron energy-loss spectroscopy, x-ray diffraction, small-angle x-ray scattering, and ultraviolet Raman spectroscopy

    NASA Astrophysics Data System (ADS)

    Mykhaylyk, Oleksandr O.; Solonin, Yurii M.; Batchelder, David N.; Brydson, Rik

    2005-04-01

    The structural properties of both nanodiamond particles synthesized by detonation and the products of their transformation into carbon onions via vacuum annealing at 1000 and 1500°C have been studied using high-resolution transmission electron microscopy (HRTEM), electron energy-loss spectroscopy, x-ray diffraction (XRD), small-angle x-ray scattering (SAXS), and Raman spectroscopy. The advantages of UV Raman spectroscopy over visible Raman spectroscopy for the analysis of these carbon nanomaterials are demonstrated. It was found that the synthesized nanodiamond particles have a composite core-shell structure comprising an ordered diamond core covered by a disordered (amorphous) outer shell formed by the mixed sp2/sp3 bonding of carbon atoms. The observed structure of the nanodiamond particles are comparable with the structure of the bucky diamond clusters comprising a diamond core and a reconstructed surface which stabilizes the cluster at the average diameter of ˜30Å, as predicted recently from theoretical studies. Assuming a spherical shape for the particles and employing a two-step boundary model of electron density distribution developed in this work to describe the SAXS patterns produced by the core-shell structure of the nanodiamond particles, it was evaluated that the average diameter of the core is ˜30Å and the average thickness of the shell is ˜8Å; values which are in agreement with results obtained from HRTEM and XRD measurements. A discrepancy between these results and average diamond crystallite size obtained from Raman spectra by applying the phonon confinement model (35-45Å ) is discussed. It is hypothesized from analysis of broadening of the XRD diamond peaks that at the nanoscale under influence of the particle shape, which is not strictly of a cubic (or spherical) symmetry, a slight hexagonal distortion of the cubic diamond structure appears in the nanodiamond particles. The transformation of the nanodiamond into carbon onions proceeds from

  8. High Resolution Imaging Spectrometer (HIRIS)

    NASA Technical Reports Server (NTRS)

    Conley, Joseph M.; Herring, Mark; Norris, David D.

    1988-01-01

    The High Resolution Imaging Spectrometer (HIRIS), related data system, orbit, and mission operations are described. The pushbroom instrument simultaneously images the terrestrial surface in 192 spectral bands from 0.4 to 2.5 microns. The swath width is 30 km and spatial resolution is 30 m. It is planned to be launched with the Earth Observing System aboard the Space Station Polar Platform in 1995. Array detectors allow concurrent integration of the signals at 192,000 detector elements.

  9. DARPA high resolution display technologies

    NASA Astrophysics Data System (ADS)

    Slusarczuk, Marko

    1990-11-01

    Much of the information of interest to pilots in flight is display-limited, and is undergoing substantial expansion due to improved sensor output and signal processing; attention is accordingly given to digitally-based instrument display imaging in the present evaluation of high-resolution cockpit display technologies. Also noted are the advantages of digitally transmitted sensor data in cases where the airborne reconnaissance user may be able to analyze telemetered airborne data in real time and respond with requests to the pilot for more detailed information of specific battlefield sites.

  10. High-Resolution Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Dozier, Jeff; Goetz, Alexander F. H.

    1990-01-01

    Earth resources observed in greater detail. High-Resolution Imaging Spectrometer, undergoing development for use in NASA's Earth Observing System, measures reflectance of Earth's surface in visible and near-infrared wavelengths. From an orbit around Earth, instrument scans surface of Earth in 200 wavelength bands simultaneously. Produces images enabling identification of minerals in rocks and soils, important algal pigments in oceans and inland waters, changes in spectra associated with biochemistry of plant canopies, compositions of atmospheric aerosols, sizes of grains in snow, and contamination of snow by impurities that absorb visible light.

  11. High Resolution Scanning Reflectarray Antenna

    NASA Technical Reports Server (NTRS)

    Romanofsky, Robert R. (Inventor); Miranda, Felix A. (Inventor)

    2000-01-01

    The present invention provides a High Resolution Scanning Reflectarray Antenna (HRSRA) for the purpose of tracking ground terminals and space craft communication applications. The present invention provides an alternative to using gimbaled parabolic dish antennas and direct radiating phased arrays. When compared to a gimbaled parabolic dish, the HRSRA offers the advantages of vibration free steering without incurring appreciable cost or prime power penalties. In addition, it offers full beam steering at a fraction of the cost of direct radiating arrays and is more efficient.

  12. High Resolution, High Frame Rate Video Technology

    NASA Technical Reports Server (NTRS)

    1990-01-01

    Papers and working group summaries presented at the High Resolution, High Frame Rate Video (HHV) Workshop are compiled. HHV system is intended for future use on the Space Shuttle and Space Station Freedom. The Workshop was held for the dual purpose of: (1) allowing potential scientific users to assess the utility of the proposed system for monitoring microgravity science experiments; and (2) letting technical experts from industry recommend improvements to the proposed near-term HHV system. The following topics are covered: (1) State of the art in the video system performance; (2) Development plan for the HHV system; (3) Advanced technology for image gathering, coding, and processing; (4) Data compression applied to HHV; (5) Data transmission networks; and (6) Results of the users' requirements survey conducted by NASA.

  13. Improved methods for high resolution electron microscopy

    SciTech Connect

    Taylor, J.R.

    1987-04-01

    Existing methods of making support films for high resolution transmission electron microscopy are investigated and novel methods are developed. Existing methods of fabricating fenestrated, metal reinforced specimen supports (microgrids) are evaluated for their potential to reduce beam induced movement of monolamellar crystals of C/sub 44/H/sub 90/ paraffin supported on thin carbon films. Improved methods of producing hydrophobic carbon films by vacuum evaporation, and improved methods of depositing well ordered monolamellar paraffin crystals on carbon films are developed. A novel technique for vacuum evaporation of metals is described which is used to reinforce microgrids. A technique is also developed to bond thin carbon films to microgrids with a polymer bonding agent. Unique biochemical methods are described to accomplish site specific covalent modification of membrane proteins. Protocols are given which covalently convert the carboxy terminus of papain cleaved bacteriorhodopsin to a free thiol. 53 refs., 19 figs., 1 tab.

  14. Improved methods for high resolution electron microscopy

    NASA Astrophysics Data System (ADS)

    Taylor, J. R.

    1987-04-01

    Existing methods of making support films for high resolution transmission electron microscopy are investigated and novel methods are developed. Existing methods of fabricating fenestrated, metal reinforced specimen supports (microgrids) are evaluated for their potential to reduce beam induced movement of monolamellar crystals of C44H90 paraffin supported on thin carbon films. Improved methods of producing hydrophobic carbon films by vacuum evaporation, and improved methods of depositing well ordered monolamellar paraffin crystals on carbon films are developed. A novel technique for vacuum evaporation of metals is described which is used to reinforce microgrids. A technique is also developed to bond thin carbon films to microgrids with a polymer bonding agent. Unique biochemical methods are described to accomplish site specific covalent modification of membrane proteins. Protocols are given which covalently convert the carboxy terminus of papain cleaved bacteriorhodopsin to a free thiol.

  15. High Resolution Thermography In Medicine

    NASA Astrophysics Data System (ADS)

    Clark, R. P.; Goff, M. R.; Culley, J. E.

    1988-10-01

    A high resolution medical thermal imaging system using an 8 element SPRI1E detector is described. Image processing is by an Intellect 100 processor and is controlled by a DEC LSI 11/23 minicomputer. Image storage is with a 170 Mbyte winchester disc together with archival storage on 12 inch diameter optical discs having a capacity of 1 Gbyte per side. The system is currently being evaluated for use in physiology and medicine. Applications outlined include the potential of thermographic screening to identify genetic carriers in X-linked hypohidrotic ectodermal dysplasia (XED), detailed vas-cular perfusion studies in health and disease and the relation-ship between cutaneous blood flow, neurological peripheral function and skin surface temperature.

  16. Enhanced High Resolution RBS System

    NASA Astrophysics Data System (ADS)

    Pollock, Thomas J.; Hass, James A.; Klody, George M.

    2011-06-01

    Improvements in full spectrum resolution with the second NEC high resolution RBS system are summarized. Results for 50 Å TiN/HfO films on Si yielding energy resolution on the order of 1 keV are also presented. Detector enhancements include improved pulse processing electronics, upgraded shielding for the MCP/RAE detector, and reduced noise generated from pumping. Energy resolution measurements on spectra front edge coupled with calculations using 0.4mStr solid angle show that beam energy spread at 400 KeV from the Pelletron® accelerator is less than 100 eV. To improve user throughput, magnet control has been added to the automatic data collection. Depth profiles derived from experimental data are discussed. For the thin films profiled, depth resolutions were on the Angstrom level with the non-linear energy/channel conversions ranging from 100 to 200 eV.

  17. High resolution spectrograph. [for LST

    NASA Technical Reports Server (NTRS)

    Peacock, K.

    1975-01-01

    The high resolution spectrograph (HRS) is designed to be used with the Large Space Telescope (LST) for the study of spectra of point and extended targets in the spectral range 110 to 410 nm. It has spectral resolutions of 1,000; 30,000; and 100,000 and has a field of view as large as 10 arc sec. The spectral range and resolution are selectable using interchangeable optical components and an echelle spectrograph is used to display a cross dispersed spectrum on the photocathode of either of 2 SEC orthicon image tubes. Provisions are included for wavelength calibration, target identification and acquisition and thermal control. The system considerations of the instrument are described.

  18. High-resolution imaging ellipsometer.

    PubMed

    Zhan, Qiwen; Leger, James R

    2002-08-01

    We report on a novel imaging ellipsometer using a high-numerical-aperture (NA) objective lens capable of measuring a two-dimensional ellipsometric signal with high resolution. Two-dimensional ellipsometric imaging is made possible by spatial filtering at the pupil plane of the objective. A Richards-Wolf vectorial diffraction model and geometrical optics model are developed to simulate the system. The thickness profile of patterned polymethyl methacrylate is measured for calibration purposes. Our instrument has a sensitivity of 5 A and provides spatial resolution of approximately 0.5 microm with 632.8-nm illumination. Its capability of measuring refractive-index variations with high spatial resolution is also demonstrated.

  19. A high resolution TDC subsystem

    SciTech Connect

    Geiges, R.; Merle, K. )

    1994-02-01

    A high resolution TDC subsystem was developed at the Institute for Nuclear Physics in Mainz. The TDC chip offers a time resolution of less than 300 ps and a programmable measurement range from 0 to 16 [mu]sec. The time measurement is done with a new, purely digital counting method. The chip can be operated in common start or common stop mode. In common start mode the chip is able to store up to 4 multiple hits per channel. The chip is used to build a transputer controlled subsystem for the measurement of the drift times of a vertical drift chamber. The design of the subsystem will be described and the first results from the tests of the prototype system will be presented.

  20. High resolution tomographic instrument development

    SciTech Connect

    Not Available

    1992-08-01

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  1. High resolution tomographic instrument development

    SciTech Connect

    Not Available

    1992-01-01

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefited greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  2. High resolution tomographic instrument development

    NASA Astrophysics Data System (ADS)

    Our recent work has concentrated on the development of high-resolution PET instrumentation reflecting in part the growing importance of PET in nuclear medicine imaging. We have developed a number of positron imaging instruments and have the distinction that every instrument has been placed in operation and has had an extensive history of application for basic research and clinical study. The present program is a logical continuation of these earlier successes. PCR-I, a single ring positron tomograph was the first demonstration of analog coding using BGO. It employed 4 mm detectors and is currently being used for a wide range of biological studies. These are of immense importance in guiding the direction for future instruments. In particular, PCR-II, a volume sensitive positron tomograph with 3 mm spatial resolution has benefitted greatly from the studies using PCR-I. PCR-II is currently in the final stages of assembly and testing and will shortly be placed in operation for imaging phantoms, animals and ultimately humans. Perhaps the most important finding resulting from our previous study is that resolution and sensitivity must be carefully balanced to achieve a practical high resolution system. PCR-II has been designed to have the detection characteristics required to achieve 3 mm resolution in human brain under practical imaging situations. The development of algorithms by the group headed by Dr. Chesler is based on a long history of prior study including his joint work with Drs. Pelc and Reiderer and Stearns. This body of expertise will be applied to the processing of data from PCR-II when it becomes operational.

  3. Mars high-resolution mapping

    NASA Astrophysics Data System (ADS)

    Batson, R. M.; Thomas, P. K.

    1991-06-01

    A series of photomosaics of high-resolution Viking Orbiter images of Mars is being prepared and published to support the Mars 1:500,000 scale geologic mapping program. More than 100 of these photomosaics were made manually, but for the last several years they have all been made digitally. The digital mosaics are published on the Mars Transverse Mercator (MTM) system, and they are also available to the appropriate principal investigators as digital files in the mosaicked digital image model (MDIM) format. The mosaics contain Viking Orbiter images with the highest available resolution: in some areas as high as 10 m/pixel. This resolution, where it exists, will support a 1:100,000 map scale. The full resolution of a mosaic is preserved in a digital file, but conventional lithographic publication of such large-scale inset maps will be done only if required by the geologic map author. When high-resolution images do not fill the neat lines of an MTM quadrangle, the medium-resolution (1/256 degrees/pixel, or 231 m/pixel) MDIM is used. The mosaics are tied by image-matching to the planetwide MDIM, in which random errors as large as 5 km (10 mm at 1:500,000 scale) are common; a few much larger, worst-case errors also occur. Because of the distribution of the errors, many large discrepancies appear along the cutlines between frames with very different resolutions. Furthermore, each block of quadrangles is compiled on its own local control system, and adjacent blocks, compiled later, are unlikely to match. Selection of areas to be mapped is based on geologic mapping proposals reviewed and recommended by the Mars 1:500,000 scale geologic mapping review panel. There is no intention to map the entire planet at this scale.

  4. HRSC: High resolution stereo camera

    USGS Publications Warehouse

    Neukum, G.; Jaumann, R.; Basilevsky, A.T.; Dumke, A.; Van Gasselt, S.; Giese, B.; Hauber, E.; Head, J. W.; Heipke, C.; Hoekzema, N.; Hoffmann, H.; Greeley, R.; Gwinner, K.; Kirk, R.; Markiewicz, W.; McCord, T.B.; Michael, G.; Muller, Jan-Peter; Murray, J.B.; Oberst, J.; Pinet, P.; Pischel, R.; Roatsch, T.; Scholten, F.; Willner, K.

    2009-01-01

    The High Resolution Stereo Camera (HRSC) on Mars Express has delivered a wealth of image data, amounting to over 2.5 TB from the start of the mapping phase in January 2004 to September 2008. In that time, more than a third of Mars was covered at a resolution of 10-20 m/pixel in stereo and colour. After five years in orbit, HRSC is still in excellent shape, and it could continue to operate for many more years. HRSC has proven its ability to close the gap between the low-resolution Viking image data and the high-resolution Mars Orbiter Camera images, leading to a global picture of the geological evolution of Mars that is now much clearer than ever before. Derived highest-resolution terrain model data have closed major gaps and provided an unprecedented insight into the shape of the surface, which is paramount not only for surface analysis and geological interpretation, but also for combination with and analysis of data from other instruments, as well as in planning for future missions. This chapter presents the scientific output from data analysis and highlevel data processing, complemented by a summary of how the experiment is conducted by the HRSC team members working in geoscience, atmospheric science, photogrammetry and spectrophotometry. Many of these contributions have been or will be published in peer-reviewed journals and special issues. They form a cross-section of the scientific output, either by summarising the new geoscientific picture of Mars provided by HRSC or by detailing some of the topics of data analysis concerning photogrammetry, cartography and spectral data analysis.

  5. High resolution time interval counter

    DOEpatents

    Condreva, Kenneth J.

    1994-01-01

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured.

  6. High resolution time interval counter

    DOEpatents

    Condreva, K.J.

    1994-07-26

    A high resolution counter circuit measures the time interval between the occurrence of an initial and a subsequent electrical pulse to two nanoseconds resolution using an eight megahertz clock. The circuit includes a main counter for receiving electrical pulses and generating a binary word--a measure of the number of eight megahertz clock pulses occurring between the signals. A pair of first and second pulse stretchers receive the signal and generate a pair of output signals whose widths are approximately sixty-four times the time between the receipt of the signals by the respective pulse stretchers and the receipt by the respective pulse stretchers of a second subsequent clock pulse. Output signals are thereafter supplied to a pair of start and stop counters operable to generate a pair of binary output words representative of the measure of the width of the pulses to a resolution of two nanoseconds. Errors associated with the pulse stretchers are corrected by providing calibration data to both stretcher circuits, and recording start and stop counter values. Stretched initial and subsequent signals are combined with autocalibration data and supplied to an arithmetic logic unit to determine the time interval in nanoseconds between the pair of electrical pulses being measured. 3 figs.

  7. High resolution imaging at Palomar

    NASA Technical Reports Server (NTRS)

    Kulkarni, Shrinivas R.

    1992-01-01

    For the last two years we have embarked on a program of understanding the ultimate limits of ground-based optical imaging. We have designed and fabricated a camera specifically for high resolution imaging. This camera has now been pressed into service at the prime focus of the Hale 5 m telescope. We have concentrated on two techniques: the Non-Redundant Masking (NRM) and Weigelt's Fully Filled Aperture (FFA) method. The former is the optical analog of radio interferometry and the latter is a higher order extension of the Labeyrie autocorrelation method. As in radio Very Long Baseline Interferometry (VLBI), both these techniques essentially measure the closure phase and, hence, true image construction is possible. We have successfully imaged binary stars and asteroids with angular resolution approaching the diffraction limit of the telescope and image quality approaching that of a typical radio VLBI map. In addition, we have carried out analytical and simulation studies to determine the ultimate limits of ground-based optical imaging, the limits of space-based interferometric imaging, and investigated the details of imaging tradeoffs of beam combination in optical interferometers.

  8. Evaluation of Advanced Bionics high resolution mode.

    PubMed

    Buechner, Andreas; Frohne-Buechner, Carolin; Gaertner, Lutz; Lesinski-Schiedat, Anke; Battmer, Rolf-Dieter; Lenarz, Thomas

    2006-07-01

    The objective of this paper is to evaluate the advantages of the Advanced Bionic high resolution mode for speech perception, through a retrospective analysis. Forty-five adult subjects were selected who had a minimum experience of three months' standard mode (mean of 10 months) before switching to high resolution mode. Speech perception was tested in standard mode immediately before fitting with high resolution mode, and again after a maximum of six months high resolution mode usage (mean of two months). A significant improvement was found, between 11 and 17%, depending on the test material. The standard mode preference does not give any indication about the improvement when switching to high resolution. Users who are converted within any study achieve a higher performance improvement than those converted in the clinical routine. This analysis proves the significant benefits of high resolution mode for users, and also indicates the need for guidelines for individual optimization of parameter settings in a high resolution mode program.

  9. High Resolution Spectroscopy to Support Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Venkataraman, Malathy Devi

    2006-01-01

    The major research activities performed during the cooperative agreement enhanced our spectroscopic knowledge of molecules of atmospheric interest such as H2O (water vapor), O3 (ozone), HCN (hydrogen cyanide), CH4 (methane), NO2 (nitrogen dioxide) and CO (carbon monoxide). The data required for the analyses were obtained from two different Fourier Transform Spectrometers (FTS); one of which is located at the National Solar Observatory (NSO) on Kitt Peak, Arizona and the other instrument is located at the Pacific Northwest National Laboratories (PNNL) at Richland, Washington. The data were analyzed using a modified multispectrum nonlinear least squares fitting algorithm developed by Dr. D. Chris Benner of the College of William and Mary. The results from these studies made significant improvements in the line positons and intensities for these molecules. The measurements of pressure broadening and pressure induced line shift coefficients and the temperature dependence of pressure broadening and pressure induced shift coefficients for hundreds of infrared transitions of HCN, CO3 CH4 and H2O were also performed during this period. Results from these studies have been used for retrievals of stratospheric gas concentration profiles from data collected by several Upper Atmospheric Research Satellite (UARS) infrared instruments as well as in the analysis of high resolution atmospheric spectra such as those acquired by space-based, ground-based, and various balloon- and aircraft-borne experiments. Our results made significant contributions in several updates of the HITRAN (HIgh resolution TRANsmission) spectral line parameters database. This database enjoys worldwide recognition in research involving diversified scientific fields. The research conducted during the period 2003-2006 has resulted in publications given in this paper. In addition to Journal publications, several oral and poster presentations were given at various Scientific conferences within the United States

  10. High-resolution slug testing.

    PubMed

    Zemansky, G M; McElwee, C D

    2005-01-01

    The hydraulic conductivity (K) variation has important ramifications for ground water flow and the transport of contaminants in ground water. The delineation of the nature of that variation can be critical to complete characterization of a site and the planning of effective and efficient remedial measures. Site-specific features (such as high-conductivity zones) need to be quantified. Our alluvial field site in the Kansas River valley exhibits spatial variability, very high conductivities, and nonlinear behavior for slug tests in the sand and gravel aquifer. High-resolution, multilevel slug tests have been performed in a number of wells that are fully screened. A general nonlinear model based on the Navier-Stokes equation, nonlinear frictional loss, non-Darcian flow, acceleration effects, radius changes in the wellbore, and a Hvorslev model for the aquifer has been used to analyze the data, employing an automated processing system that runs within the Excel spreadsheet program. It is concluded that slug tests can provide the necessary data to identify the nature of both horizontal and vertical K variation in an aquifer and that improved delineation or higher resolution of K structure is possible with shorter test intervals. The gradation into zones of higher conductivity is sharper than seen previously, and the maximum conductivity observed is greater than previously measured. However, data from this project indicate that well development, the presence of fines, and the antecedent history of the well are important interrelated factors in regard to slug-test response and can prevent obtaining consistent results in some cases.

  11. New experimental evidences of Au-Cu2S core-shell nanoparticles and atomic resolution imaging by aberration-corrected STEM

    NASA Astrophysics Data System (ADS)

    Khanal, Subarna; Casillas, Gilberto; Bhattarai, Nabraj; Velazquez-Salazar, J. Jesus; Yacaman, Miguel Jose

    2013-03-01

    Au-Cu2S core-shell nanoparticles present different properties than their monometallic counterparts, opening a wide range of possibilities for different applications. Au-Cu2S core-shell nanostructures have raised interest for their many applications in photoelectronic, sensing, catalysis and so on. Au and Au-Cu2S core-shell nanoparticles were prepared by using a modified polyol method. First Au seeds were prepared by reducing HAuCl4.xH2O in ethylene glycol (EG) in the presence of poly(vinylpyrrolidone) (PVP) as a polymer surfactant. Then Cu2S shells were overgrown on Au core seeds by reducing CuSO4 in EG with PVP. The morphology and structural characteristics of Au and Au-Cu2S nanostructures were studied in detail using scanning electron microcopy HITACHI S-5500 and high resolution transmission electron microscope (HRTEM), a resolution 0.19 nm. Moreover, the Cs-corrected scanning transmission electron microscopy (Cs-corrected STEM) technique allowed us to probe the structure at the atomic level of these nanoparticles revealing new structural information. We determined the structure of the four main polyhedral morphologies obtained in the synthesis: decahedral, icosahedral, triangular plates, and rods. This project was supported by grants from the National Center for Research Resources (5 G12RR013646-12) and the National Institute on Minority Health and Health Disparities (G12MD007591).

  12. Few-layer graphene as a support film for transmission electron microscopy imaging of nanoparticles.

    PubMed

    McBride, James R; Lupini, Andrew R; Schreuder, Michael A; Smith, Nathanael J; Pennycook, Stephen J; Rosenthal, Sandra J

    2009-12-01

    One consistent limitation for high-resolution imaging of small nanoparticles is the high background signal from the amorphous carbon support film. With interest growing for smaller and smaller nanostructures, state of the art electron microscopes are becoming necessary for rudimentary tasks, such as nanoparticle sizing. As a monolayer of carbon, free-standing graphene represents the ultimate support film for nanoparticle imaging. In this work, conventional high-resolution transmission electron microscopy (HRTEM) and aberration-corrected scanning transmission electron microscopy (STEM) were used to assess the benefits and feasibility of few-layer graphene support films. Suspensions of few-layer graphene to produce the support films were prepared by simple sonication of exfoliated graphite. The greatest benefit was observed for conventional HRTEM, where lattice resolved imaging of sub 2 nm CdSe nanocrystals was achieved. The few-layer graphene films were also used as a support film for C(s)-corrected STEM and electron energy loss spectroscopy of CuInSe(2) nanocrystals. PMID:20356171

  13. High resolution single particle refinement in EMAN2.1.

    PubMed

    Bell, James M; Chen, Muyuan; Baldwin, Philip R; Ludtke, Steven J

    2016-05-01

    EMAN2.1 is a complete image processing suite for quantitative analysis of grayscale images, with a primary focus on transmission electron microscopy, with complete workflows for performing high resolution single particle reconstruction, 2-D and 3-D heterogeneity analysis, random conical tilt reconstruction and subtomogram averaging, among other tasks. In this manuscript we provide the first detailed description of the high resolution single particle analysis pipeline and the philosophy behind its approach to the reconstruction problem. High resolution refinement is a fully automated process, and involves an advanced set of heuristics to select optimal algorithms for each specific refinement task. A gold standard FSC is produced automatically as part of refinement, providing a robust resolution estimate for the final map, and this is used to optimally filter the final CTF phase and amplitude corrected structure. Additional methods are in-place to reduce model bias during refinement, and to permit cross-validation using other computational methods.

  14. High resolution single particle refinement in EMAN2.1.

    PubMed

    Bell, James M; Chen, Muyuan; Baldwin, Philip R; Ludtke, Steven J

    2016-05-01

    EMAN2.1 is a complete image processing suite for quantitative analysis of grayscale images, with a primary focus on transmission electron microscopy, with complete workflows for performing high resolution single particle reconstruction, 2-D and 3-D heterogeneity analysis, random conical tilt reconstruction and subtomogram averaging, among other tasks. In this manuscript we provide the first detailed description of the high resolution single particle analysis pipeline and the philosophy behind its approach to the reconstruction problem. High resolution refinement is a fully automated process, and involves an advanced set of heuristics to select optimal algorithms for each specific refinement task. A gold standard FSC is produced automatically as part of refinement, providing a robust resolution estimate for the final map, and this is used to optimally filter the final CTF phase and amplitude corrected structure. Additional methods are in-place to reduce model bias during refinement, and to permit cross-validation using other computational methods. PMID:26931650

  15. High resolution analysis of the readthrough domain of beet necrotic yellow vein virus readthrough protein: a KTER motif is important for efficient transmission of the virus by Polymyxa betae.

    PubMed

    Tamada, T; Schmitt, C; Saito, M; Guilley, H; Richards, K; Jonard, G

    1996-07-01

    The 5'-terminal cistron of beet necrotic yellow vein furovirus RNA 2 encodes the 21 kDa major viral coat protein and terminates with an amber stop codon which can undergo suppression to give rise to a 75 kDa readthrough (RT) protein referred to as P75. P75 is a minor component of virions and the 54 kDa RT domain following the coat protein sequence is important both for virus assembly and transmission by the fungal vector Polymyxa betae. To better define the regions of the RT domain involved in these two steps, RNA 2 transcripts encoding different in-frame RT domain deletion mutants were tested for their ability to form virions when inoculated to plants with the other viral RNAs and to be fungus-transmitted. All deletions in the N-terminal half of the RT domain interfered with virus assembly and partially or completely inhibited fungus transmission. A 4 1 1 nucleotide deletion within the C-terminal half of the RT domain did not inhibit assembly but blocked fungus transmission of the virus. Alanine scanning mutagenesis within the aforesaid 4 1 1 nucleotide subdomain identified a peptide motif (KTER) which is important for the fungus transmission process. PMID:8757975

  16. High resolution scanning electron microscopy of plasmodesmata.

    PubMed

    Brecknock, Sarah; Dibbayawan, Teresa P; Vesk, Maret; Vesk, Peter A; Faulkner, Christine; Barton, Deborah A; Overall, Robyn L

    2011-10-01

    Symplastic transport occurs between neighbouring plant cells through functionally and structurally dynamic channels called plasmodesmata (PD). Relatively little is known about the composition of PD or the mechanisms that facilitate molecular transport into neighbouring cells. While transmission electron microscopy (TEM) provides 2-dimensional information about the structural components of PD, 3-dimensional information is difficult to extract from ultrathin sections. This study has exploited high-resolution scanning electron microscopy (HRSEM) to reveal the 3-dimensional morphology of PD in the cell walls of algae, ferns and higher plants. Varied patterns of PD were observed in the walls, ranging from uniformly distributed individual PD to discrete clusters. Occasionally the thick walls of the giant alga Chara were fractured, revealing the surface morphology of PD within. External structures such as spokes, spirals and mesh were observed surrounding the PD. Enzymatic digestions of cell wall components indicate that cellulose or pectin either compose or stabilise the extracellular spokes. Occasionally, the PD were fractured open and desmotubule-like structures and other particles were observed in their central regions. Our observations add weight to the argument that Chara PD contain desmotubules and are morphologically similar to higher plant PD.

  17. High resolution magnetic spectrometer SHARAQ in RIBF

    SciTech Connect

    Shimoura, S.

    2007-05-22

    For a new spectroscopy of nuclei using intense RI beams at RIBF, we started the SHARAQ project where a high-resolution SHARAQ spectrometer is being constructed together with a high-resolution secondary beam line. Physics motivation and the specification of the spectrometer are presented.

  18. High resolution scintillation detector with semiconductor readout

    DOEpatents

    Levin, Craig S.; Hoffman, Edward J.

    2000-01-01

    A novel high resolution scintillation detector array for use in radiation imaging such as high resolution Positron Emission Tomography (PET) which comprises one or more parallelepiped crystals with at least one long surface of each crystal being in intimate contact with a semiconductor photodetector such that photons generated within each crystal by gamma radiation passing therethrough is detected by the photodetector paired therewith.

  19. Superconducting High Resolution Fast-Neutron Spectrometers

    SciTech Connect

    Hau, Ionel Dragos

    2006-01-01

    Superconducting high resolution fast-neutron calorimetric spectrometers based on 6LiF and TiB{sub 2} absorbers have been developed. These novel cryogenic spectrometers measure the temperature rise produced in exothermal (n, α) reactions with fast neutrons in 6Li and 10B-loaded materials with heat capacity C operating at temperatures T close to 0.1 K. Temperature variations on the order of 0.5 mK are measured with a Mo/Cu thin film multilayer operated in the transition region between its superconducting and its normal state. The advantage of calorimetry for high resolution spectroscopy is due to the small phonon excitation energies kBT on the order of μeV that serve as signal carriers, resulting in an energy resolution ΔE ~ (kBT2C)1/2, which can be well below 10 keV. An energy resolution of 5.5 keV has been obtained with a Mo/Cu superconducting sensor and a TiB2 absorber using thermal neutrons from a 252Cf neutron source. This resolution is sufficient to observe the effect of recoil nuclei broadening in neutron spectra, which has been related to the lifetime of the first excited state in 7Li. Fast-neutron spectra obtained with a 6Li-enriched LiF absorber show an energy resolution of 16 keV FWHM, and a response in agreement with the 6Li(n, α)3H reaction cross section and Monte Carlo simulations for energies up to several MeV. The energy resolution of order of a few keV makes this novel instrument applicable to fast-neutron transmission spectroscopy based on the unique elemental signature provided by the neutron absorption and scattering resonances. The optimization of the energy resolution based on analytical and numerical models of the detector response is discussed in the context of these applications.

  20. High-resolution color images of Io

    NASA Technical Reports Server (NTRS)

    Mcewen, A. S.; Soderblom, L. A.

    1984-01-01

    Color versions of the highest resolution Voyager images of Io were produced by combining the low resolution color images with the high resolution, clear filter images. High resolution versions of the orange, blue, and violet filter images are produced by: orange = high-res clear * low-res orange / low-res clear blue = high-res clear * low-res blue / low-res clear violet = high-res clear * low-res violet / low-res clear. The spectral responses of the high and low resolution clear filter images cancel, leaving the color, while the spatial frequencies of the two low resolution images cancel, leaving the high resolution.

  1. Evidence of sharp and diffuse domain walls in BiFeO3 by means of unit-cell-wise strain and polarization maps obtained with high resolution scanning transmission electron microscopy.

    PubMed

    Lubk, A; Rossell, M D; Seidel, J; He, Q; Yang, S Y; Chu, Y H; Ramesh, R; Hÿtch, M J; Snoeck, E

    2012-07-27

    Domain walls (DWs) substantially influence a large number of applications involving ferroelectric materials due to their limited mobility when shifted during polarization switching. The discovery of greatly enhanced conduction at BiFeO(3) DWs has highlighted yet another role of DWs as a local material state with unique properties. However, the lack of precise information on the local atomic structure is still hampering microscopical understanding of DW properties. Here, we examine the atomic structure of BiFeO(3) 109° DWs with pm precision by a combination of high-angle annular dark-field scanning transmission electron microscopy and a dedicated structural analysis. By measuring simultaneously local polarization and strain, we provide direct experimental proof for the straight DW structure predicted by ab initio calculations as well as the recently proposed theory of diffuse DWs, thus resolving a long-standing discrepancy between experimentally measured and theoretically predicted DW mobilities.

  2. NOAA's Use of High-Resolution Imagery

    NASA Technical Reports Server (NTRS)

    Hund, Erik

    2007-01-01

    NOAA's use of high-resolution imagery consists of: a) Shoreline mapping and nautical chart revision; b) Coastal land cover mapping; c) Benthic habitat mapping; d) Disaster response; and e) Imagery collection and support for coastal programs.

  3. Aberration correction of unstable resonators

    NASA Technical Reports Server (NTRS)

    Lang, Robert J. (Inventor)

    1994-01-01

    Construction of aspheric reflectors for unstable resonator lasers to provide an arbitrary laser mode inside the resonator to correct aberrations of an output beam by the construction of the shape of an end reflector opposite the output reflector of the resonator cavity, such as aberrations resulting from refraction of a beam exiting the solid of the resonator having an index of refraction greater than 1 or to produce an aberration in the output beam that will precisely compensate for the aberration of an optical train into which the resonator beam is coupled.

  4. Aberration correction past and present.

    PubMed

    Hawkes, P W

    2009-09-28

    Electron lenses are extremely poor: if glass lenses were as bad, we should see as well with the naked eye as with a microscope! The demonstration by Otto Scherzer in 1936 that skillful lens design could never eliminate the spherical and chromatic aberrations of rotationally symmetric electron lenses was therefore most unwelcome and the other great electron optician of those years, Walter Glaser, never ceased striving to find a loophole in Scherzer's proof. In the wartime and early post-war years, the first proposals for correcting C(s) were made and in 1947, in a second milestone paper, Scherzer listed these and other ways of correcting lenses; soon after, Dennis Gabor invented holography for the same purpose. These approaches will be briefly summarized and the work that led to the successful implementation of quadupole-octopole and sextupole correctors in the 1990 s will be analysed. In conclusion, the elegant role of image algebra in describing image formation and processing and, above all, in developing new methods will be mentioned. PMID:19687058

  5. Phase and birefringence aberration correction

    DOEpatents

    Bowers, Mark; Hankla, Allen

    1996-01-01

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90.degree. such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system.

  6. Phase and birefringence aberration correction

    DOEpatents

    Bowers, M.; Hankla, A.

    1996-07-09

    A Brillouin enhanced four wave mixing phase conjugate mirror corrects phase aberrations of a coherent electromagnetic beam and birefringence induced upon that beam. The stimulated Brillouin scattering (SBS) phase conjugation technique is augmented to include Brillouin enhanced four wave mixing (BEFWM). A seed beam is generated by a main oscillator which arrives at the phase conjugate cell before the signal beams in order to initiate the Brillouin effect. The signal beam which is being amplified through the amplifier chain is split into two perpendicularly polarized beams. One of the two beams is chosen to be the same polarization as some component of the seed beam, the other orthogonal to the first. The polarization of the orthogonal beam is then rotated 90{degree} such that it is parallel to the other signal beam. The three beams are then focused into cell containing a medium capable of Brillouin excitation. The two signal beams are focused such that they cross the seed beam path before their respective beam waists in order to achieve BEFWM or the two signal beams are focused to a point or points contained within the focused cone angle of the seed beam to achieve seeded SBS, and thus negate the effects of all birefringent and material aberrations in the system. 5 figs.

  7. Multimodal adaptive optics for depth-enhanced high-resolution ophthalmic imaging

    NASA Astrophysics Data System (ADS)

    Hammer, Daniel X.; Mujat, Mircea; Iftimia, Nicusor V.; Lue, Niyom; Ferguson, R. Daniel

    2010-02-01

    We developed a multimodal adaptive optics (AO) retinal imager for diagnosis of retinal diseases, including glaucoma, diabetic retinopathy (DR), age-related macular degeneration (AMD), and retinitis pigmentosa (RP). The development represents the first ever high performance AO system constructed that combines AO-corrected scanning laser ophthalmoscopy (SLO) and swept source Fourier domain optical coherence tomography (SSOCT) imaging modes in a single compact clinical prototype platform. The SSOCT channel operates at a wavelength of 1 μm for increased penetration and visualization of the choriocapillaris and choroid, sites of major disease activity for DR and wet AMD. The system is designed to operate on a broad clinical population with a dual deformable mirror (DM) configuration that allows simultaneous low- and high-order aberration correction. The system also includes a wide field line scanning ophthalmoscope (LSO) for initial screening, target identification, and global orientation; an integrated retinal tracker (RT) to stabilize the SLO, OCT, and LSO imaging fields in the presence of rotational eye motion; and a high-resolution LCD-based fixation target for presentation to the subject of stimuli and other visual cues. The system was tested in a limited number of human subjects without retinal disease for performance optimization and validation. The system was able to resolve and quantify cone photoreceptors across the macula to within ~0.5 deg (~100-150 μm) of the fovea, image and delineate ten retinal layers, and penetrate to resolve targets deep into the choroid. In addition to instrument hardware development, analysis algorithms were developed for efficient information extraction from clinical imaging sessions, with functionality including automated image registration, photoreceptor counting, strip and montage stitching, and segmentation. The system provides clinicians and researchers with high-resolution, high performance adaptive optics imaging to help

  8. Design and Performance Characteristics of the ORNL AdvancedMicroscopy Laboratory and JEOL 2200FS-AC Aberration-CorrectedSTEM/TEM

    SciTech Connect

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

    2005-02-15

    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 aTEM 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 affecting the instrument performance. In STEM high-angle annular dark-field (HA-ADF) mode, images of a thin Si crystal in<110>zone axis orientation, after primary aberrations in the illuminating beam were optimally corrected, showed a significant vibration effect. The microscope is fitted with three magnetically levitated turbo pumps (one on the column at about the specimen position,and two near floor level) that pump the Omega energy filter and detector chamber. These pumps run at 48,000 rpm, precisely equivalent to 800Hz. It was determined that the upper turbo pump was contributing essentially all of the 800Hz signal to the image, and in fact that the pump was defective. After replacing the pump with one significantly quieter than the original, the Si atomic column image and associated diffractogram(Fig. 4b) show a much-reduced effect of the 800Hz signal, but still some residual effect from the turbo pump. The upper pump will be removed from the main column to an adjacent frame on the floor, and will have a large-diameter, well-damped, pump line to the original connection to the column to effectively isolate the pump from the column. If the 800Hz signal results from mechanical vibrations, they will be damped, and if the signal results from acoustic coupling to the column, it can be damped by appropriate acoustic materials.

  9. High-resolution analytical imaging and electron holography of magnetite particles in amyloid cores of Alzheimer’s disease

    PubMed Central

    Plascencia-Villa, Germán; Ponce, Arturo; Collingwood, Joanna F.; Arellano-Jiménez, M. Josefina; Zhu, Xiongwei; Rogers, Jack T.; Betancourt, Israel; José-Yacamán, Miguel; Perry, George

    2016-01-01

    Abnormal accumulation of brain metals is a key feature of Alzheimer’s disease (AD). Formation of amyloid-β plaque cores (APC) is related to interactions with biometals, especially Fe, Cu and Zn, but their particular structural associations and roles remain unclear. Using an integrative set of advanced transmission electron microscopy (TEM) techniques, including spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), nano-beam electron diffraction, electron holography and analytical spectroscopy techniques (EDX and EELS), we demonstrate that Fe in APC is present as iron oxide (Fe3O4) magnetite nanoparticles. Here we show that Fe was accumulated primarily as nanostructured particles within APC, whereas Cu and Zn were distributed through the amyloid fibers. Remarkably, these highly organized crystalline magnetite nanostructures directly bound into fibrillar Aβ showed characteristic superparamagnetic responses with saturated magnetization with circular contours, as observed for the first time by off-axis electron holography of nanometer scale particles. PMID:27121137

  10. High-resolution analytical imaging and electron holography of magnetite particles in amyloid cores of Alzheimer’s disease

    NASA Astrophysics Data System (ADS)

    Plascencia-Villa, Germán; Ponce, Arturo; Collingwood, Joanna F.; Arellano-Jiménez, M. Josefina; Zhu, Xiongwei; Rogers, Jack T.; Betancourt, Israel; José-Yacamán, Miguel; Perry, George

    2016-04-01

    Abnormal accumulation of brain metals is a key feature of Alzheimer’s disease (AD). Formation of amyloid-β plaque cores (APC) is related to interactions with biometals, especially Fe, Cu and Zn, but their particular structural associations and roles remain unclear. Using an integrative set of advanced transmission electron microscopy (TEM) techniques, including spherical aberration-corrected scanning transmission electron microscopy (Cs-STEM), nano-beam electron diffraction, electron holography and analytical spectroscopy techniques (EDX and EELS), we demonstrate that Fe in APC is present as iron oxide (Fe3O4) magnetite nanoparticles. Here we show that Fe was accumulated primarily as nanostructured particles within APC, whereas Cu and Zn were distributed through the amyloid fibers. Remarkably, these highly organized crystalline magnetite nanostructures directly bound into fibrillar Aβ showed characteristic superparamagnetic responses with saturated magnetization with circular contours, as observed for the first time by off-axis electron holography of nanometer scale particles.

  11. RAPID DAMAGE ASSESSMENT FROM HIGH RESOLUTION IMAGERY

    SciTech Connect

    Vijayaraj, Veeraraghavan; Bright, Eddie A; Bhaduri, Budhendra L

    2008-01-01

    Disaster impact modeling and analysis uses huge volumes of image data that are produced immediately following a natural or an anthropogenic disaster event. Rapid damage assessment is the key to time critical decision support in disaster management to better utilize available response resources and accelerate recovery and relief efforts. But exploiting huge volumes of high resolution image data for identifying damaged areas with robust consistency in near real time is a challenging task. In this paper, we present an automated image analysis technique to identify areas of structural damage from high resolution optical satellite data using features based on image content.

  12. High-resolution electron microscopy of advanced materials

    SciTech Connect

    Mitchell, T.E.; Kung, H.H.; Sickafus, K.E.; Gray, G.T. III; Field, R.D.; Smith, J.F.

    1997-11-01

    This final report chronicles a three-year, Laboratory Directed Research and Development (LDRD) project at Los Alamos National Laboratory (LANL). The High-Resolution Electron Microscopy Facility has doubled in size and tripled in quality since the beginning of the three-year period. The facility now includes a field-emission scanning electron microscope, a 100 kV field-emission scanning transmission electron microscope (FE-STEM), a 300 kV field-emission high-resolution transmission electron microscope (FE-HRTEM), and a 300 kV analytical transmission electron microscope. A new orientation imaging microscope is being installed. X-ray energy dispersive spectrometers for chemical analysis are available on all four microscopes; parallel electron energy loss spectrometers are operational on the FE-STEM and FE-HRTEM. These systems enable evaluation of local atomic bonding, as well as chemical composition in nanometer-scale regions. The FE-HRTEM has a point-to-point resolution of 1.6 {angstrom}, but the resolution can be pushed to its information limit of 1 {angstrom} by computer reconstruction of a focal series of images. HRTEM has been used to image the atomic structure of defects such as dislocations, grain boundaries, and interfaces in a variety of materials from superconductors and ferroelectrics to structural ceramics and intermetallics.

  13. Characterization of high-resolution HafSOx inorganic resists

    NASA Astrophysics Data System (ADS)

    Oleksak, R. P.; Herman, G. S.

    2014-04-01

    Inorganic resists are of considerable interest for advanced lithography at the nanoscale due to the potential for high resolution, low line width roughness (LWR), and high sensitivity. Historically inorganic resists suffered from low sensitivity, however approaches have been identified to increase sensitivity while maintaining high contrast. An aqueous precursor of Hf(OH)4-2x-2y(O2)x(SO4)y·qH2O (HafSOx) has been demonstrated with excellent sensitivity to EUV and electrons, while still obtaining high resolution and low LWR. In this work, we characterize both HafSOx precursor solutions and spin-coated thin films using high-resolution transmission electron microscopy (HR-TEM) with energy-dispersive X-ray spectroscopy (EDS) elemental analysis. HR-TEM of precursor solutions drop cast onto TEM grids confirmed the presence of nanoscale particles. HR-TEM cross sectional images showed that spin-coated HafSOx films are initially uniform in appearance and composition for thin (12 nm) films, however thicker (30 nm) films display segregation of species leading to multilayer structures. Regardless of film thickness, extended exposure to the high energy TEM electron beam induces significant migration of oxygen species to the Si interface. These species result in the formation of SiOx layers that increase in thickness with an increase in TEM electron beam dose. Sulfate is also very mobile in the films and likely assists in the significant condensation exhibited in completely processed films.

  14. Progress in high-resolution x-ray holographic microscopy

    SciTech Connect

    Jacobsen, C.; Kirz, J.; Howells, M.; McQuaid, K.; Rothman, S.; Feder, R.; Sayre, D.

    1987-07-01

    Among the various types of x-ray microscopes that have been demonstrated, the holographic microscope has had the largest gap between promise and performance. The difficulties of fabricating x-ray optical elements have led some to view holography as the most attractive method for obtaining the ultimate in high resolution x-ray micrographs; however, we know of no investigations prior to 1987 that clearly demonstrated submicron resolution in reconstructed images. Previous efforts suffered from problems such as limited resolution and dynamic range in the recording media, low coherent x-ray flux, and aberrations and diffraction limits in visible light reconstruction. We have addressed the recording limitations through the use of an undulator x-ray source and high-resolution photoresist recording media. For improved results in the readout and reconstruction steps, we have employed metal shadowing and transmission electron microscopy, along with numerical reconstruction techniques. We believe that this approach will allow holography to emerge as a practical method of high-resolution x-ray microscopy. 30 refs., 4 figs.

  15. Modeling high-resolution broadband discourse in complex adaptive systems.

    PubMed

    Dooley, Kevin J; Corman, Steven R; McPhee, Robert D; Kuhn, Timothy

    2003-01-01

    Numerous researchers and practitioners have turned to complexity science to better understand human systems. Simulation can be used to observe how the microlevel actions of many human agents create emergent structures and novel behavior in complex adaptive systems. In such simulations, communication between human agents is often modeled simply as message passing, where a message or text may transfer data, trigger action, or inform context. Human communication involves more than the transmission of texts and messages, however. Such a perspective is likely to limit the effectiveness and insight that we can gain from simulations, and complexity science itself. In this paper, we propose a model of how close analysis of discursive processes between individuals (high-resolution), which occur simultaneously across a human system (broadband), dynamically evolve. We propose six different processes that describe how evolutionary variation can occur in texts-recontextualization, pruning, chunking, merging, appropriation, and mutation. These process models can facilitate the simulation of high-resolution, broadband discourse processes, and can aid in the analysis of data from such processes. Examples are used to illustrate each process. We make the tentative suggestion that discourse may evolve to the "edge of chaos." We conclude with a discussion concerning how high-resolution, broadband discourse data could actually be collected. PMID:12876447

  16. A High-Resolution Stopwatch for Cents

    ERIC Educational Resources Information Center

    Gingl, Z.; Kopasz, K.

    2011-01-01

    A very low-cost, easy-to-make stopwatch is presented to support various experiments in mechanics. The high-resolution stopwatch is based on two photodetectors connected directly to the microphone input of a sound card. Dedicated free open-source software has been developed and made available to download. The efficiency is demonstrated by a free…

  17. High-resolution two dimensional advective transport

    USGS Publications Warehouse

    Smith, P.E.; Larock, B.E.

    1989-01-01

    The paper describes a two-dimensional high-resolution scheme for advective transport that is based on a Eulerian-Lagrangian method with a flux limiter. The scheme is applied to the problem of pure-advection of a rotated Gaussian hill and shown to preserve the monotonicity property of the governing conservation law.

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

    NASA Astrophysics Data System (ADS)

    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.

  19. High Resolution Higher Energy X-ray Microscope for Mesoscopic Materials

    NASA Astrophysics Data System (ADS)

    Snigireva, I.; Snigirev, A.

    2013-10-01

    We developed a novel X-ray microscopy technique to study mesoscopically structured materials, employing compound refractive lenses. The easily seen advantage of lens-based methodology is the possibility to retrieve high resolution diffraction pattern and real-space images in the same experimental setup. Methodologically the proposed approach is similar to the studies of crystals by high resolution transmission electron microscopy. The proposed microscope was applied for studying of mesoscopic materials such as natural and synthetic opals, inverted photonic crystals.

  20. Imaging plasmodesmata with high-resolution scanning electron microscopy.

    PubMed

    Barton, Deborah A; Overall, Robyn L

    2015-01-01

    High-resolution scanning electron microscopy (HRSEM) is an effective tool to investigate the distribution of plasmodesmata within plant cell walls as well as to probe their complex, three-dimensional architecture. It is a useful alternative to traditional transmission electron microscopy (TEM) in which plasmodesmata are sectioned to reveal their internal substructures. Benefits of adopting an HRSEM approach to studies of plasmodesmata are that the specimen preparation methods are less complex and time consuming than for TEM, many plasmodesmata within a large region of tissue can be imaged in a single session, and three-dimensional information is readily available without the need for reconstructing TEM serial sections or employing transmission electron tomography, both of which are lengthy processes. Here we describe methods to prepare plant samples for HRSEM using pre- or postfixation extraction of cellular material in order to visualize plasmodesmata embedded within plant cell walls.

  1. High resolution 3D nonlinear integrated inversion

    NASA Astrophysics Data System (ADS)

    Li, Yong; Wang, Xuben; Li, Zhirong; Li, Qiong; Li, Zhengwen

    2009-06-01

    The high resolution 3D nonlinear integrated inversion method is based on nonlinear theory. Under layer control, the log data from several wells (or all wells) in the study area and seismic trace data adjacent to the wells are input to a network with multiple inputs and outputs and are integratedly trained to obtain an adaptive weight function of the entire study area. Integrated nonlinear mapping relationships are built and updated by the lateral and vertical geologic variations of the reservoirs. Therefore, the inversion process and its inversion results can be constrained and controlled and a stable seismic inversion section with high resolution with velocity inversion, impedance inversion, and density inversion sections, can be gained. Good geologic effects have been obtained in model computation tests and real data processing, which verified that this method has high precision, good practicality, and can be used for quantitative reservoir analysis.

  2. High-Resolution X-Ray Telescopes

    NASA Technical Reports Server (NTRS)

    ODell, Stephen L.; Brissenden, Roger J.; Davis, William; Elsner, Ronald F.; Elvis, Martin; Freeman, Mark; Gaetz, Terry; Gorenstein, Paul; Gubarev, Mikhail V.

    2010-01-01

    Fundamental needs for future x-ray telescopes: a) Sharp images => excellent angular resolution. b) High throughput => large aperture areas. Generation-X optics technical challenges: a) High resolution => precision mirrors & alignment. b) Large apertures => lots of lightweight mirrors. Innovation needed for technical readiness: a) 4 top-level error terms contribute to image size. b) There are approaches to controlling those errors. Innovation needed for manufacturing readiness. Programmatic issues are comparably challenging.

  3. High resolution schemes for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Harten, A.

    1983-01-01

    A class of new explicit second order accurate finite difference schemes for the computation of weak solutions of hyperbolic conservation laws is presented. These highly nonlinear schemes are obtained by applying a nonoscillatory first order accurate scheme to an appropriately modified flux function. The so-derived second order accurate schemes achieve high resolution while preserving the robustness of the original nonoscillatory first order accurate scheme. Numerical experiments are presented to demonstrate the performance of these new schemes.

  4. High-Resolution Traction Force Microscopy

    PubMed Central

    Plotnikov, Sergey V.; Sabass, Benedikt; Schwarz, Ulrich S.; Waterman, Clare M.

    2015-01-01

    Cellular forces generated by the actomyosin cytoskeleton and transmitted to the extracellular matrix (ECM) through discrete, integrin-based protein assemblies, that is, focal adhesions, are critical to developmental morphogenesis and tissue homeostasis, as well as disease progression in cancer. However, quantitative mapping of these forces has been difficult since there has been no experimental technique to visualize nanonewton forces at submicrometer spatial resolution. Here, we provide detailed protocols for measuring cellular forces exerted on two-dimensional elastic substrates with a high-resolution traction force microscopy (TFM) method. We describe fabrication of polyacrylamide substrates labeled with multiple colors of fiducial markers, functionalization of the substrates with ECM proteins, setting up the experiment, and imaging procedures. In addition, we provide the theoretical background of traction reconstruction and experimental considerations important to design a high-resolution TFM experiment. We describe the implementation of a new algorithm for processing of images of fiducial markers that are taken below the surface of the substrate, which significantly improves data quality. We demonstrate the application of the algorithm and explain how to choose a regularization parameter for suppression of the measurement error. A brief discussion of different ways to visualize and analyze the results serves to illustrate possible uses of high-resolution TFM in biomedical research. PMID:24974038

  5. High-Resolution US of Rheumatologic Diseases.

    PubMed

    Taljanovic, Mihra S; Melville, David M; Gimber, Lana H; Scalcione, Luke R; Miller, Margaret D; Kwoh, C Kent; Klauser, Andrea S

    2015-01-01

    For the past 15 years, high-resolution ultrasonography (US) is being routinely and increasingly used for initial evaluation and treatment follow-up of rheumatologic diseases. This imaging technique is performed by using high-frequency linear transducers and has proved to be a powerful diagnostic tool in evaluation of articular erosions, simple and complex joint and bursal effusions, tendon sheath effusions, and synovitis, with results comparable to those of magnetic resonance imaging, excluding detection of bone marrow edema. Crystal deposition diseases including gouty arthropathy and calcium pyrophosphate deposition disease (CPPD) have characteristic appearances at US, enabling differentiation between these two diseases and from inflammatory arthropathies. Enthesopathy, which frequently accompanies psoriatic and reactive arthritis, also has a characteristic appearance at high-resolution US, distinguishing these two entities from other inflammatory and metabolic arthropathies. The presence of Doppler signal in examined joints, bursae, and tendon sheaths indicates active synovitis. Microbubble echo contrast agents augment detection of tissue vascularity and may act in the future as a drug delivery vehicle. Frequently, joint, tendon sheath, and bursal fluid aspirations and therapeutic injections are performed under US guidance. The authors describe the high-resolution US technique including gray-scale, color or power Doppler, and contrast agent-enhanced US that is used in evaluation of rheumatologic diseases of the wrist and hand and the ankle and foot in their routine clinical practice. This article demonstrates imaging findings of normal joints, rheumatoid arthritis, gouty arthritis, CPPD, psoriatic and reactive arthritis, and osteoarthritis.

  6. Dry-contact technique for high-resolution ultrasonic imaging.

    PubMed

    Tohmyoh, Hironori; Saka, Masumi

    2003-06-01

    To accomplish a high-resolution ultrasonic imaging without wetting a sample, the efficiency of the dry-contact ultrasonic transmission is discussed. In this study, a dry-contact interface is formed on a sample by inserting a thin film between water and a sample, and the pressure is working on the interface by evacuating the air between the film and the sample. A model of dry-contact ultrasonic transmission is presented to assess the signal loss accompanied with the transmission. From the determination of the signal loss caused by the transmission using various films, it was found that the higher frequency ultrasound is transmitted effectively into the sample by selecting an optimum film, which can keep the displacement continuity between the film and the sample during ultrasonic transmission. At last, ultrasonic imaging with the sufficient signal-to-noise ratio (SNR) and high lateral resolution was performed on the delamination in a package and the jointing interface of the ball-grid-array package without wetting the packages.

  7. Possibilities and limitations of advanced transmission electron microscopy for carbon-based nanomaterials

    PubMed Central

    Bittencourt, Carla; Van Tendeloo, Gustaaf

    2015-01-01

    Summary A major revolution for electron microscopy in the past decade is the introduction of aberration correction, which enables one to increase both the spatial resolution and the energy resolution to the optical limit. Aberration correction has contributed significantly to the imaging at low operating voltages. This is crucial for carbon-based nanomaterials which are sensitive to electron irradiation. The research of carbon nanomaterials and nanohybrids, in particular the fundamental understanding of defects and interfaces, can now be carried out in unprecedented detail by aberration-corrected transmission electron microscopy (AC-TEM). This review discusses new possibilities and limits of AC-TEM at low voltage, including the structural imaging at atomic resolution, in three dimensions and spectroscopic investigation of chemistry and bonding. In situ TEM of carbon-based nanomaterials is discussed and illustrated through recent reports with particular emphasis on the underlying physics of interactions between electrons and carbon atoms. PMID:26425406

  8. A Portable, High Resolution, Surface Measurement Device

    NASA Technical Reports Server (NTRS)

    Ihlefeld, Curtis M.; Burns, Bradley M.; Youngquist, Robert C.

    2012-01-01

    A high resolution, portable, surface measurement device has been demonstrated to provide micron-resolution topographical plots. This device was specifically developed to allow in-situ measurements of defects on the Space Shuttle Orbiter windows, but is versatile enough to be used on a wide variety of surfaces. This paper discusses the choice of an optical sensor and then the decisions required to convert a lab bench optical measurement device into an ergonomic portable system. The necessary trade-offs between performance and portability are presented along with a description of the device developed to measure Orbiter window defects.

  9. High resolution SAR applications and instrument design

    NASA Technical Reports Server (NTRS)

    Dionisio, C.; Torre, A.

    1993-01-01

    The Synthetic Aperture Radar (SAR) has viewed, in the last two years, a huge increment of interest from many preset and potential users. The good spatial resolution associated to the all weather capability lead to considering SAR not only a scientific instrument but a tool for verifying and controlling the daily human relationships with the Earth Environment. New missions were identified for SAR as spatial resolution became lower than three meters: disasters, pollution, ships traffic, volcanic eruptions, earthquake effect are only a few of the possible objects which can be effectively detected, controlled and monitored by SAR mounted on satellites. High resolution radar design constraints and dimensioning are discussed.

  10. High resolution millimeter-wave imaging sensor

    NASA Technical Reports Server (NTRS)

    Wilson, W. J.; Howard, R. J.; Parks, G. S.

    1985-01-01

    A scanning 3-mm radiometer is described that has been built for use on a small aircraft to produce real time high resolution images of the ground when atmospheric conditions such as smoke, dust, and clouds make IR and visual sensors unusable. The sensor can be used for a variety of remote sensing applications such as measurements of snow cover and snow water equivalent, precipitation mapping, vegetation type and extent, surface moisture and temperature, and surface thermal inertia. The advantages of millimeter waves for cloud penetration and the ability to observe different physical phenomena make this system an attractive supplement to visible and IR remote sensing systems.

  11. High resolution extremity CT for biomechanics modeling

    SciTech Connect

    Ashby, A.E.; Brand, H.; Hollerbach, K.; Logan, C.M.; Martz, H.E.

    1995-09-23

    With the advent of ever more powerful computing and finite element analysis (FEA) capabilities, the bone and joint geometry detail available from either commercial surface definitions or from medical CT scans is inadequate. For dynamic FEA modeling of joints, precise articular contours are necessary to get appropriate contact definition. In this project, a fresh cadaver extremity was suspended in parafin in a lucite cylinder and then scanned with an industrial CT system to generate a high resolution data set for use in biomechanics modeling.

  12. A High Resolution Scale-of-four

    DOE R&D Accomplishments Database

    Fitch, V.

    1949-08-25

    A high resolution scale-of-four has been developed to be used in conjunction with the nuclear particle detection devices in applications where the counting rate is unusually high. Specifically, it is intended to precede the commercially available medium resolution scaling circuits and so decrease the resolving time of the counting system. The circuit will function reliably on continuously recurring pulses separated by less than 0.1 microseconds. It will resolve two pulses (occurring at a moderate repetition rate) which are spaced at 0.04 microseconds. A five-volt input signal is sufficient to actuate the device.

  13. High Resolution Image From Viking Lander 1

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Viking 1 took this high-resolution picture today, its third day on Mars. Distance from the camera to the nearfield (bottom) is about 4 meters (13 feet); to the horizon, about 3 kilometers (1.8 miles). The photo shows numerous angular blocks ranging in size from a few centimeters to several meters. The surface between the blocks is composed of fine-grained material. Accumulation of some fine-grained material behind blocks indicates wind deposition of dust and sand downwind of obstacles. The large block on the horizon is about 4 meters (13 feet) wide. Distance across the horizon is about 34 meters (110 feet).

  14. High Resolution Spectroscopy with Submillimeter-Wave

    NASA Astrophysics Data System (ADS)

    Kumar, Vinay; Dave, Hemant

    2003-03-01

    In order to explain the characteristic features of planetary atmosphere, detection and precise measurements of environmentally important gases such as CO, CIO, No becomes necessary. Since most of the polyatomic molecules have (ro-vibrational) transitions in submillimeter region 100 μ-1000μ), probing in this wavelength region is vital. The specific rotational and vibrational states are the result of interactions between different atoms in the molecule. Since each molecule has a unique arrangement of atoms, it has an exclusive submillimeter signature. We are developing a portable heterodyne receiver system at Physical Research Laboratory, Ahmedabad to perform high-resolution spectroscopy in this wavelength region.

  15. High-Resolution Scintimammography: A Pilot Study

    SciTech Connect

    Rachel F. Brem; Joelle M. Schoonjans; Douglas A. Kieper; Stan Majewski; Steven Goodman; Cahid Civelek

    2002-07-01

    This study evaluated a novel high-resolution breast-specific gamma camera (HRBGC) for the detection of suggestive breast lesions. Methods: Fifty patients (with 58 breast lesions) for whom a scintimammogram was clinically indicated were prospectively evaluated with a general-purpose gamma camera and a novel HRBGC prototype. The results of conventional and high-resolution nuclear studies were prospectively classified as negative (normal or benign) or positive (suggestive or malignant) by 2 radiologists who were unaware of the mammographic and histologic results. All of the included lesions were confirmed by pathology. Results: There were 30 benign and 28 malignant lesions. The sensitivity for detection of breast cancer was 64.3% (18/28) with the conventional camera and 78.6% (22/28) with the HRBGC. The specificity with both systems was 93.3% (28/30). For the 18 nonpalpable lesions, sensitivity was 55.5% (10/18) and 72.2% (13/18) with the general-purpose camera and the HRBGC, respectively. For lesions 1 cm, 7 of 15 were detected with the general-purpose camera and 10 of 15 with the HRBGC. Four lesions (median size, 8.5 mm) were detected only with the HRBGC and were missed by the conventional camera. Conclusion: Evaluation of indeterminate breast lesions with an HRBGC results in improved sensitivity for the detection of cancer, with greater improvement shown for nonpalpable and 1-cm lesions.

  16. High Resolution Camera for Mapping Titan Surface

    NASA Technical Reports Server (NTRS)

    Reinhardt, Bianca

    2011-01-01

    Titan, Saturn's largest moon, has a dense atmosphere and is the only object besides Earth to have stable liquids at its surface. The Cassini/Huygens mission has revealed the extraordinary breadth of geological processes shaping its surface. Further study requires high resolution imaging of the surface, which is restrained by light absorption by methane and scattering from aerosols. The Visual and Infrared Mapping Spectrometer (VIMS) onboard the Cassini spacecraft has demonstrated that Titan's surface can be observed within several windows in the near infrared, allowing us to process several regions in order to create a geological map and to determine the morphology. Specular reflections monitored on the lakes of the North Pole show little scattering at 5 microns, which, combined with the present study of Titan's northern pole area, refutes the paradigm that only radar can achieve high resolution mapping of the surface. The present data allowed us to monitor the evolution of lakes, to identify additional lakes at the Northern Pole, to examine Titan's hypothesis of non-synchronous rotation and to analyze the albedo of the North Pole surface. Future missions to Titan could carry a camera with 5 micron detectors and a carbon fiber radiator for weight reduction.

  17. High Resolution Laser Spectroscopy of Rhenium Carbide

    NASA Astrophysics Data System (ADS)

    Adam, Allan G.; Hall, Ryan M.; Linton, Colan; Tokaryk, Dennis

    2014-06-01

    The first spectroscopic study of rhenium carbide, ReC, has been performed using both low and high resolution techniques to collect rotationally resolved electronic spectra from 420 to 500nm. Laser-induced fluorescence (LIF), and dispersed fluorescence (DF) techniques were employed. ReC was formed in our laser ablation molecular jet apparatus by ablating a rhenium target rod in the presence of 1% methane in helium. The low resolution spectrum identified four bands of an electronic system belonging to ReC, three of which have been studied so far. Extensive hyperfine structure composed of six hyperfine components was observed in the high resolution spectrum, as well as a clear distinction between the 187ReC and 185ReC isotopologues. The data seems consistent with a ^4Π - ^4Σ- transition, as was predicted before experimentation. Dispersed fluorescence spectra allowed us to determine the ground state vibrational frequency (ωe"=994.4 ± 0.3 wn), and to identify a low-lying electronically excited state at Te"=1118.4 ± 0.4 wn with a vibrational frequency of ωe"=984 ± 2 wn. Personal communication, F. Grein, University of New Brunswick

  18. Common high-resolution MMW scene generator

    NASA Astrophysics Data System (ADS)

    Saylor, Annie V.; McPherson, Dwight A.; Satterfield, H. DeWayne; Sholes, William J.; Mobley, Scott B.

    2001-08-01

    The development of a modularized millimeter wave (MMW) target and background high resolution scene generator is reported. The scene generator's underlying algorithms are applicable to both digital and real-time hardware-in-the-loop (HWIL) simulations. The scene generator will be configurable for a variety of MMW and multi-mode sensors employing state of the art signal processing techniques. At present, digital simulations for MMW and multi-mode sensor development and testing are custom-designed by the seeker vendor and are verified, validated, and operated by both the vendor and government in simulation-based acquisition. A typical competition may involve several vendors, each requiring high resolution target and background models for proper exercise of seeker algorithms. There is a need and desire by both the government and sensor vendors to eliminate costly re-design and re-development of digital simulations. Additional efficiencies are realized by assuring commonality between digital and HWIL simulation MMW scene generators, eliminating duplication of verification and validation efforts.

  19. High-Resolution PET Detector. Final report

    SciTech Connect

    Karp, Joel

    2014-03-26

    The objective of this project was to develop an understanding of the limits of performance for a high resolution PET detector using an approach based on continuous scintillation crystals rather than pixelated crystals. The overall goal was to design a high-resolution detector, which requires both high spatial resolution and high sensitivity for 511 keV gammas. Continuous scintillation detectors (Anger cameras) have been used extensively for both single-photon and PET scanners, however, these instruments were based on NaI(Tl) scintillators using relatively large, individual photo-multipliers. In this project we investigated the potential of this type of detector technology to achieve higher spatial resolution through the use of improved scintillator materials and photo-sensors, and modification of the detector surface to optimize the light response function.We achieved an average spatial resolution of 3-mm for a 25-mm thick, LYSO continuous detector using a maximum likelihood position algorithm and shallow slots cut into the entrance surface.

  20. Comparative Very-High-Resolution VUV Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lewis, B. R.; Gibson, S. T.; Baldwin, K. G. H.; Dooley, P. M.; Waring, K.

    Despite their importance to the photochemistry of the terrestrial atmosphere, and many experimental studies, previous characterization of the Schumann-Runge (SR) bands of O2, B3 Σ u- <- X3 Σ_g^- (v, 0) (1750-2050 Å) has been limited by poor experimental resolution. In addition, our understanding of the SR spectrum is incomplete, many rovibrational transitions in the perturbed region of the spectrum [B(v > 15)] remaining unassigned. We review new very-high-resolution measurements of the O2 photoabsorption cross section in the SR bands. Tunable, narrow-bandwidth background vacuum-ultraviolet (VUV) radiation for the measurements ( 7 × 105 resolving power) was generated by the two-photon-resonant difference-frequency four-wave mixing in Xe of excimer-pumped dye-laser radiation. With the aid of these cross-section measurements, rovibrational and line-shape analyses have led to new insights into the molecular structure and predissociation dynamics of O2. The current VUV laser-spectroscopic measurements are shown to compare favourably with results from two other very-high-resolution experimental techniques, namely laser-induced fluorescence spectroscopy and VUV Fourier-transform spectroscopy, the latter performed using a synchrotron source.

  1. Limiting liability via high resolution image processing

    SciTech Connect

    Greenwade, L.E.; Overlin, T.K.

    1996-12-31

    The utilization of high resolution image processing allows forensic analysts and visualization scientists to assist detectives by enhancing field photographs, and by providing the tools and training to increase the quality and usability of field photos. Through the use of digitized photographs and computerized enhancement software, field evidence can be obtained and processed as `evidence ready`, even in poor lighting and shadowed conditions or darkened rooms. These images, which are most often unusable when taken with standard camera equipment, can be shot in the worst of photographic condition and be processed as usable evidence. Visualization scientists have taken the use of digital photographic image processing and moved the process of crime scene photos into the technology age. The use of high resolution technology will assist law enforcement in making better use of crime scene photography and positive identification of prints. Valuable court room and investigation time can be saved and better served by this accurate, performance based process. Inconclusive evidence does not lead to convictions. Enhancement of the photographic capability helps solve one major problem with crime scene photos, that if taken with standard equipment and without the benefit of enhancement software would be inconclusive, thus allowing guilty parties to be set free due to lack of evidence.

  2. High-Resolution Shadowing of Transfer RNA

    PubMed Central

    Abermann, Reinhard J.; Yoshikami, Doju

    1972-01-01

    High-resolution shadowing with metals that melt at high temperatures was used to study macromolecules. Molecules of transfer RNA shadowed with tantalum-tungsten are readily visualized in an electron microscope. Mounting procedures for tRNA were perfected that reproducibly gave uniform distributions of both monomeric and dimeric tRNA particles, and allowed a statistical assessment of their gross shapes and sizes. Monomeric tRNA yielded a fairly homogeneous population of rod-shaped particles, with axial dimensions of about 40 × 85 Å. Dimers of yeast alanine tRNA held together by hydrogen bonds and dimers constructed by covalent linkage of the amino-acid acceptor (3′-) termini of monomers both gave slightly more heterogeneous populations of particles. Yet, their structures were also basically rod shaped, with their lengths ranging to about twice that of the monomer; this result indicates an end-to-end arrangement of the monomeric units within both dimers. These results suggest that the amino-acid acceptor terminus and the anticodon region are at the ends of the rod-shaped, dehydrated tRNA monomer visible by electron microscopy, consistent with the generally accepted view of tRNA structure in solution suggested by other workers using other methods. This study demonstrates that high-resolution shadowing with tantalum-tungsten provides a means to examine the three-dimensional structures of relatively small biological macromolecules. Images PMID:4504373

  3. High Resolution Spectroscopy to Support Atmospheric Measurements

    NASA Technical Reports Server (NTRS)

    Venkataraman, Malathy Devi

    2003-01-01

    Spectroscopic parameters (such as line position, intensity, broadening and shifting coefficients and their temperature dependences, line mixing coefficients etc.) for various molecular species of atmospheric interest are determined. In order to achieve these results, infrared spectra of several molecular bands are obtained using high-resolution recording instruments such as tunable diode laser spectrometer and Fourier transform spectrometers. Using sophisticated analysis routines (Multispectrum nonlinear least squares technique) these high-resolution infrared spectra are processed to determine the various spectral line parameters that are cited above. Spectra were taken using the McMath-Pierce Fourier transform spectrometer (FTS) at the National Solar Observatory on Kitt Peak, Arizona as well as the Bruker FTS at the Pacific Northwest National Laboratory (PNNL) at Richland, Washington. Most of the spectra are acquired not only at room temperature, but also at several different cold temperatures. This procedure is necessary to study the variation of the spectral line parameters as a function of temperature in order to simulate the Earth's and other planetary atmospheric environments. Depending upon the strength or weakness of the various bands recorded and analyzed, the length(s) of the absorption cells in which the gas samples under study are kept varied from a few centimeters up to several meters and the sample temperatures varied from approximately +30 C to -63 C. Research on several infrared bands of various molecular species and their isotopomers are undertaken. Those studies are briefly described.

  4. Observation of microporous cesium salts of 12-tungstosilicic acid using scanning transmission electron microscopy.

    PubMed

    Hiyoshi, Norihito; Kamiya, Yuichi

    2015-06-21

    Heteropolyanions and their arrays in microporous cesium salts of 12-tungstosilicic acid, Cs2.5H1.5[SiW12O40] and Cs4.0[SiW12O40], were observed by aberration-corrected scanning transmission electron microscopy. Microstructures that form micropores in the polyoxometalates were visualized.

  5. A compact high-resolution X-ray powder diffractometer

    PubMed Central

    Fewster, Paul F.; Trout, David R. D.

    2013-01-01

    A new powder diffractometer operating in transmission mode is described. It can work as a rapid very compact instrument or as a high-resolution instrument, and the sample preparation is simplified. The incident beam optics create pure Cu Kα1 radiation, giving rise to peak widths of ∼0.1° in 2θ in compact form with a sample-to-detector minimum radius of 55 mm, reducing to peak widths of <0.05° in high-resolution mode by increasing the detector radius to 240 mm. The resolution of the diffractometer is shown to be governed by a complex mixture of angular divergence, sample size, diffraction effects and the dimensions of the detector pixels. The data can be collected instantaneously, which combined with trivial sample preparation and no sample alignment, makes it a suitable method for very rapid phase identification. As the detector is moved further from the sample, the angular step from the pixel dimension is reduced and the resolution improves significantly for very detailed studies, including structure determination and analysis of the microstructure. The advantage of this geometry is that the resolution of the diffractometer can be calculated precisely and the instrumental artefacts can be analysed easily without a sample present. The performance is demonstrated with LaB6 and paracetamol, and a critical appraisal of the uncertainties in the measurements is presented. The instantaneous data collection offers possibilities in dynamic experiments. PMID:24282331

  6. Local sample thickness determination via scanning transmission electron microscopy defocus series.

    PubMed

    Beyer, A; Straubinger, R; Belz, J; Volz, K

    2016-05-01

    The usable aperture sizes in (scanning) transmission electron microscopy ((S)TEM) have significantly increased in the past decade due to the introduction of aberration correction. In parallel with the consequent increase of convergence angle the depth of focus has decreased severely and optical sectioning in the STEM became feasible. Here we apply STEM defocus series to derive the local sample thickness of a TEM sample. To this end experimental as well as simulated defocus series of thin Si foils were acquired. The systematic blurring of high resolution high angle annular dark field images is quantified by evaluating the standard deviation of the image intensity for each image of a defocus series. The derived dependencies exhibit a pronounced maximum at the optimum defocus and drop to a background value for higher or lower values. The full width half maximum (FWHM) of the curve is equal to the sample thickness above a minimum thickness given by the size of the used aperture and the chromatic aberration of the microscope. The thicknesses obtained from experimental defocus series applying the proposed method are in good agreement with the values derived from other established methods. The key advantages of this method compared to others are its high spatial resolution and that it does not involve any time consuming simulations.

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

    PubMed

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

    2011-06-01

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

  8. Clementine High Resolution Camera Mosaicking Project

    NASA Technical Reports Server (NTRS)

    1998-01-01

    This report constitutes the final report for NASA Contract NASW-5054. This project processed Clementine I high resolution images of the Moon, mosaicked these images together, and created a 22-disk set of compact disk read-only memory (CD-ROM) volumes. The mosaics were produced through semi-automated registration and calibration of the high resolution (HiRes) camera's data against the geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic produced by the US Geological Survey (USGS). The HiRes mosaics were compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution nadir-looking observations. The images were spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel for sub-polar mosaics (below 80 deg. latitude) and using the stereographic projection at a scale of 30 m/pixel for polar mosaics. Only images with emission angles less than approximately 50 were used. Images from non-mapping cross-track slews, which tended to have large SPICE errors, were generally omitted. The locations of the resulting image population were found to be offset from the UV/Vis basemap by up to 13 km (0.4 deg.). Geometric control was taken from the 100 m/pixel global and 150 m/pixel polar USGS Clementine Basemap Mosaics compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Radiometric calibration was achieved by removing the image nonuniformity dominated by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap, that approximately transform the 8-bit HiRes data to photometric units. The sub-polar mosaics are divided into tiles that cover approximately 1.75 deg. of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. Polar mosaics are tiled into squares 2250 pixels on a

  9. High Resolution Powder Diffraction and Structure Determination

    SciTech Connect

    Cox, D. E.

    1999-04-23

    It is clear that high-resolution synchrotrons X-ray powder diffraction is a very powerful and convenient tool for material characterization and structure determination. Most investigations to date have been carried out under ambient conditions and have focused on structure solution and refinement. The application of high-resolution techniques to increasingly complex structures will certainly represent an important part of future studies, and it has been seen how ab initio solution of structures with perhaps 100 atoms in the asymmetric unit is within the realms of possibility. However, the ease with which temperature-dependence measurements can be made combined with improvements in the technology of position-sensitive detectors will undoubtedly stimulate precise in situ structural studies of phase transitions and related phenomena. One challenge in this area will be to develop high-resolution techniques for ultra-high pressure investigations in diamond anvil cells. This will require highly focused beams and very precise collimation in front of the cell down to dimensions of 50 {micro}m or less. Anomalous scattering offers many interesting possibilities as well. As a means of enhancing scattering contrast it has applications not only to the determination of cation distribution in mixed systems such as the superconducting oxides discussed in Section 9.5.3, but also to the location of specific cations in partially occupied sites, such as the extra-framework positions in zeolites, for example. Another possible application is to provide phasing information for ab initio structure solution. Finally, the precise determination of f as a function of energy through an absorption edge can provide useful information about cation oxidation states, particularly in conjunction with XANES data. In contrast to many experiments at a synchrotron facility, powder diffraction is a relatively simple and user-friendly technique, and most of the procedures and software for data analysis

  10. Clementine High Resolution Camera Mosaicking Project

    NASA Astrophysics Data System (ADS)

    1998-10-01

    This report constitutes the final report for NASA Contract NASW-5054. This project processed Clementine I high resolution images of the Moon, mosaicked these images together, and created a 22-disk set of compact disk read-only memory (CD-ROM) volumes. The mosaics were produced through semi-automated registration and calibration of the high resolution (HiRes) camera's data against the geometrically and photometrically controlled Ultraviolet/Visible (UV/Vis) Basemap Mosaic produced by the US Geological Survey (USGS). The HiRes mosaics were compiled from non-uniformity corrected, 750 nanometer ("D") filter high resolution nadir-looking observations. The images were spatially warped using the sinusoidal equal-area projection at a scale of 20 m/pixel for sub-polar mosaics (below 80 deg. latitude) and using the stereographic projection at a scale of 30 m/pixel for polar mosaics. Only images with emission angles less than approximately 50 were used. Images from non-mapping cross-track slews, which tended to have large SPICE errors, were generally omitted. The locations of the resulting image population were found to be offset from the UV/Vis basemap by up to 13 km (0.4 deg.). Geometric control was taken from the 100 m/pixel global and 150 m/pixel polar USGS Clementine Basemap Mosaics compiled from the 750 nm Ultraviolet/Visible Clementine imaging system. Radiometric calibration was achieved by removing the image nonuniformity dominated by the HiRes system's light intensifier. Also provided are offset and scale factors, achieved by a fit of the HiRes data to the corresponding photometrically calibrated UV/Vis basemap, that approximately transform the 8-bit HiRes data to photometric units. The sub-polar mosaics are divided into tiles that cover approximately 1.75 deg. of latitude and span the longitude range of the mosaicked frames. Images from a given orbit are map projected using the orbit's nominal central latitude. Polar mosaics are tiled into squares 2250 pixels on a

  11. High-Resolution Broadband Spectral Interferometry

    SciTech Connect

    Erskine, D J; Edelstein, J

    2002-08-09

    We demonstrate solar spectra from a novel interferometric method for compact broadband high-resolution spectroscopy. The spectral interferometer (SI) is a hybrid instrument that uses a spectrometer to externally disperse the output of a fixed-delay interferometer. It also has been called an externally dispersed interferometer (EDI). The interferometer can be used with linear spectrometers for imaging spectroscopy or with echelle spectrometers for very broad-band coverage. EDI's heterodyning technique enhances the spectrometer's response to high spectral-density features, increasing the effective resolution by factors of several while retaining its bandwidth. The method is extremely robust to instrumental insults such as focal spot size or displacement. The EDI uses no moving parts, such as purely interferometric FTS spectrometers, and can cover a much wider simultaneous bandpass than other internally dispersed interferometers (e.g. HHS or SHS).

  12. High resolution wavefront measurement of aspheric optics

    NASA Astrophysics Data System (ADS)

    Erichsen, I.; Krey, S.; Heinisch, J.; Ruprecht, A.; Dumitrescu, E.

    2008-08-01

    With the recently emerged large volume production of miniature aspheric lenses for a wide range of applications, a new fast fully automatic high resolution wavefront measurement instrument has been developed. The Shack-Hartmann based system with reproducibility better than 0.05 waves is able to measure highly aspheric optics and allows for real time comparison with design data. Integrated advanced analysis tools such as calculation of Zernike coefficients, 2D-Modulation Transfer Function (MTF), Point Spread Function (PSF), Strehl-Ratio and the measurement of effective focal length (EFL) as well as flange focal length (FFL) allow for the direct verification of lens properties and can be used in a development as well as in a production environment.

  13. High-resolution climate simulation using CAM

    NASA Astrophysics Data System (ADS)

    Bacmeister, J.; Neale, R. B.; Hannay, C.; Lauritzen, P. H.; Wehner, M. F.

    2012-12-01

    Thanks to the development of highly scalable dynamical cores that can exploit massively parallel computer architectures, we expect that global climate models in the next decade will run routinely at horizontal resolutions of 25 km or finer. Early results at these resolutions show clear improvements in simulating climatologically and societally-important mesoscale meteorology such as tropical cyclones. Improvements in regional circulations likely associated with topography are also obtained. Nevertheless many long-standing biases in climate simulations, e.g., the "double ITCZ" bias in precipitation, remain remarkably insensitive to increased resolution. This talk will present high-resolution global simulations using the community atmosphere model. Sensitivity of tropical cyclone climatology and precipitation statistics to model physics suites will be shown

  14. Ultra-high resolution computed tomography imaging

    DOEpatents

    Paulus, Michael J.; Sari-Sarraf, Hamed; Tobin, Jr., Kenneth William; Gleason, Shaun S.; Thomas, Jr., Clarence E.

    2002-01-01

    A method for ultra-high resolution computed tomography imaging, comprising the steps of: focusing a high energy particle beam, for example x-rays or gamma-rays, onto a target object; acquiring a 2-dimensional projection data set representative of the target object; generating a corrected projection data set by applying a deconvolution algorithm, having an experimentally determined a transfer function, to the 2-dimensional data set; storing the corrected projection data set; incrementally rotating the target object through an angle of approximately 180.degree., and after each the incremental rotation, repeating the radiating, acquiring, generating and storing steps; and, after the rotating step, applying a cone-beam algorithm, for example a modified tomographic reconstruction algorithm, to the corrected projection data sets to generate a 3-dimensional image. The size of the spot focus of the beam is reduced to not greater than approximately 1 micron, and even to not greater than approximately 0.5 microns.

  15. Low noise and high resolution microchannel plate

    NASA Astrophysics Data System (ADS)

    Liu, Shulin; Pan, Jingsheng; Deng, Guangxu; Su, Detan; Xu, Zhiqing; Zhang, Yanyun

    2008-02-01

    To improve the Figure of Merit (FOM) and reduce the Equivalent Background Input (EBI) and Fixed-Pattern-Noise (FPN) in image intensifier, NVT (North Night Vision Technology Co., Ltd) has been researching and developing a low noise and high resolution Micro Channel Plate (MCP). The density of dark current of this new MCP is less than 0.5PA/cm2 (when MCP voltage at 1000V). The FPN and scintillation noise are reduced remarkably. Channel diameter is 6 μm and open area ratio is 60%~70%. The vacuum bakeout temperature could be as high as 500°C. This new kind of MCP will be extensively used in the supper generation and the third generation image intensifiers.

  16. High resolution analysis of satellite gradiometry

    NASA Technical Reports Server (NTRS)

    Colombo, O. L.

    1989-01-01

    Satellite gravity gradiometry is a technique now under development which, by the middle of the next decade, may be used for the high resolution charting from space of the gravity field of the earth and, afterwards, of other planets. Some data analysis schemes are reviewed for getting detailed gravity maps from gradiometry on both a global and a local basis. It also presents estimates of the likely accuracies of such maps, in terms of normalized spherical harmonics expansions, both using gradiometry alone and in combination with data from a Global Positioning System (GPS) receiver carried on the same spacecraft. It compares these accuracies with those of current and future maps obtained from other data (conventional tracking, satellite-satellite tracking, etc.), and also with the spectra of various signals of geophysical interest.

  17. High-resolution MRI: in vivo histology?

    PubMed Central

    Bridge, Holly; Clare, Stuart

    2005-01-01

    For centuries scientists have been fascinated with the question of how the brain works. Investigators have looked at both where different functions are localized and how the anatomical microstructure varies across the brain surface. Here we discuss how advances in magnetic resonance imaging (MRI) have allowed in vivo visualization of the fine structure of the brain that was previously only visible in post-mortem brains. We present data showing the correspondence between definitions of the primary visual cortex defined anatomically using very high-resolution MRI and functionally using functional MRI. We consider how this technology can be applied to allow the investigation of brains that differ from normal, and what this ever-evolving technology may be able to reveal about in vivo brain structure in the next few years. PMID:16553313

  18. A high resolution ultraviolet Shuttle glow spectrograph

    NASA Technical Reports Server (NTRS)

    Carruthers, George R.

    1993-01-01

    The High Resolution Shuttle Glow Spectrograph-B (HRSGS-B) is a small payload being developed by the Naval Research Laboratory. It is intended for study of shuttle surface glow in the 180-400 nm near- and middle-ultraviolet wavelength range, with a spectral resolution of 0.2 nm. It will search for, among other possible features, the band systems of excited NO which result from surface-catalyzed combination of N and O. It may also detect O2 Hertzberg bands and N2 Vegard-Kaplan bands resulting from surface recombination. This wavelength range also includes possible N2+ and OH emissions. The HRSGS-B will be housed in a Get Away Special canister, mounted in the shuttle orbiter payload bay, and will observe the glow on the tail of the orbiter.

  19. High-resolution reconstruction for terahertz imaging.

    PubMed

    Xu, Li-Min; Fan, Wen-Hui; Liu, Jia

    2014-11-20

    We present a high-resolution (HR) reconstruction model and algorithms for terahertz imaging, taking advantage of super-resolution methodology and algorithms. The algorithms used include projection onto a convex sets approach, iterative backprojection approach, Lucy-Richardson iteration, and 2D wavelet decomposition reconstruction. Using the first two HR reconstruction methods, we successfully obtain HR terahertz images with improved definition and lower noise from four low-resolution (LR) 22×24 terahertz images taken from our homemade THz-TDS system at the same experimental conditions with 1.0 mm pixel. Using the last two HR reconstruction methods, we transform one relatively LR terahertz image to a HR terahertz image with decreased noise. This indicates potential application of HR reconstruction methods in terahertz imaging with pulsed and continuous wave terahertz sources.

  20. HIRIS - The High Resolution Imaging Spectrometer

    NASA Technical Reports Server (NTRS)

    Dozier, Jeff

    1988-01-01

    The High-Resolution Imaging Spectrometer (HIRIS) is a JPL facility instrument designed for NASA's Earth Observing System (Eos).It will have 10-nm wide spectral bands from 0.4-2.5 microns at 30 m spatial resolution over a 30 km swath. The spectral resolution allows identification of many minerals in rocks and soils, important algal pigments in oceans and inland waters, spectral changes associated with plant canopy biochemistry, composition of atmospheric aerosols, and grain size of snow and its contamination by absorbing impurities. The bands wil have 12-bit quantization over a dynamic range suitable for bright targets, such as snow. For targets of low brightness, such as water bodies, image-motion compensation will allow gains up to a factor of eight to increase signal-to-noise ratios. In the 824-km orbit altitude proposed for Eos, the crosstrack pointing capability will allow 4-5 views during a 16-day revisit cycle.

  1. Constructing a WISE High Resolution Galaxy Atlas

    NASA Astrophysics Data System (ADS)

    Jarrett, T. H.; Masci, F.; Tsai, C. W.; Petty, S.; Cluver, M.; Assef, Roberto J.; Benford, D.; Blain, A.; Bridge, C.; Donoso, E.; Eisenhardt, P.; Fowler, J.; Koribalski, B.; Lake, S.; Neill, James D.; Seibert, M.; Sheth, K.; Stanford, S.; Wright, E.

    2012-08-01

    After eight months of continuous observations, the Wide-field Infrared Survey Explorer (WISE) mapped the entire sky at 3.4 μm, 4.6 μm, 12 μm, and 22 μm. We have begun a dedicated WISE High Resolution Galaxy Atlas project to fully characterize large, nearby galaxies and produce a legacy image atlas and source catalog. Here we summarize the deconvolution techniques used to significantly improve the spatial resolution of WISE imaging, specifically designed to study the internal anatomy of nearby galaxies. As a case study, we present results for the galaxy NGC 1566, comparing the WISE enhanced-resolution image processing to that of Spitzer, Galaxy Evolution Explorer, and ground-based imaging. This is the first paper in a two-part series; results for a larger sample of nearby galaxies are presented in the second paper.

  2. Computer synthesis of high resolution electron micrographs

    NASA Technical Reports Server (NTRS)

    Nathan, R.

    1976-01-01

    Specimen damage, spherical aberration, low contrast and noisy sensors combine to prevent direct atomic viewing in a conventional electron microscope. The paper describes two methods for obtaining ultra-high resolution in biological specimens under the electron microscope. The first method assumes the physical limits of the electron objective lens and uses a series of dark field images of biological crystals to obtain direct information on the phases of the Fourier diffraction maxima; this information is used in an appropriate computer to synthesize a large aperture lens for a 1-A resolution. The second method assumes there is sufficient amplitude scatter from images recorded in focus which can be utilized with a sensitive densitometer and computer contrast stretching to yield fine structure image details. Cancer virus characterization is discussed as an illustrative example. Numerous photographs supplement the text.

  3. High resolution detection system of capillary electrophoresis

    NASA Astrophysics Data System (ADS)

    Wang, Jie; Wang, Li Qiang; Shi, Yan; Zheng, Hua; Lu, Zu Kang

    2007-12-01

    The capillary electrophoresis (CE) with laser induced fluorescence detection (LIFD) system was founded according to confocal theory. The 3-D adjustment of the exciting and collecting optical paths was realized. The photomultiplier tube (PMT) is used and the signals are processed by a software designed by ourselves. Under computer control, high voltage is applied to appropriate reservoirs and to inject and separate DNA samples respectively. Two fluorescent dyes Thiazole Orange (TO) and SYBR Green I were contrasted. With both of the dyes, high signals-to-noise images were obtained with the CE-LIFD system. The single-bases can be distinguished from the electrophoretogram and high resolution of DNA sample separation was obtained.

  4. High-resolution adaptive spiking sonar.

    PubMed

    Alvarez, Fernando J; Kuc, Roman

    2009-05-01

    A new sonar system based on the conventional 6500 ranging module is presented that generates a sequence of spikes whose temporal density is related to the strength of the received echo. This system notably improves the resolution of a previous system by shortening the discharge cycle of the integrator included in the module. The operation is controlled by a PIC18F452 device, which can adapt the duration of the discharge to changing features of the echo, providing the system with a novel adaptive behavior. The performance of the new sensor is characterized and compared with that of the previous system by performing rotational scans of simple objects with different reflecting strengths. Some applications are suggested that exploit the high resolution and adaptability of this sensor.

  5. Constructing a WISE High Resolution Galaxy Atlas

    NASA Technical Reports Server (NTRS)

    Jarrett, T. H.; Masci, F.; Tsai, C. W.; Petty, S.; Cluver, M.; Assef, Roberto J.; Benford, D.; Blain, A.; Bridge, C.; Donoso, E.; Eisenhardt, P.; Fowler, J.; Koribalski, B.; Lake, S.; Neill, James D.; Seibert, M.; Stanford, S.; Wright, E.

    2012-01-01

    After eight months of continuous observations, the Wide-field Infrared Survey Explorer (WISE) mapped the entire sky at 3.4 micron, 4.6 micron, 12 micron, and 22 micron. We have begun a dedicated WISE High Resolution Galaxy Atlas project to fully characterize large, nearby galaxies and produce a legacy image atlas and source catalog. Here we summarize the deconvolution techniques used to significantly improve the spatial resolution of WISE imaging, specifically designed to study the internal anatomy of nearby galaxies. As a case study, we present results for the galaxy NGC 1566, comparing the WISE enhanced-resolution image processing to that of Spitzer, Galaxy Evolution Explorer, and ground-based imaging. This is the first paper in a two-part series; results for a larger sample of nearby galaxies are presented in the second paper.

  6. Limits of simulation based high resolution EBSD.

    PubMed

    Alkorta, Jon

    2013-08-01

    High resolution electron backscattered diffraction (HREBSD) is a novel technique for a relative determination of both orientation and stress state in crystals through digital image correlation techniques. Recent works have tried to use simulated EBSD patterns as reference patterns to achieve the absolute orientation and stress state of crystals. However, a precise calibration of the pattern centre location is needed to avoid the occurrence of phantom stresses. A careful analysis of the projective transformation involved in the formation of EBSD patterns has permitted to understand these phantom stresses. This geometrical analysis has been confirmed by numerical simulations. The results indicate that certain combinations of crystal strain states and sample locations (pattern centre locations) lead to virtually identical EBSD patterns. This ambiguity makes the problem of solving the absolute stress state of a crystal unfeasible in a single-detector configuration. PMID:23676453

  7. High-Resolution Anamorphic SPECT Imaging

    PubMed Central

    Durko, Heather L.; Barrett, Harrison H.; Furenlid, Lars R.

    2015-01-01

    We have developed a gamma-ray imaging system that combines a high-resolution silicon detector with two sets of movable, half-keel-edged copper-tungsten blades configured as crossed slits. These apertures can be positioned independently between the object and detector, producing an anamorphic image in which the axial and transaxial magnifications are not constrained to be equal. The detector is a 60 mm × 60 mm, one-millimeter-thick, one-megapixel silicon double-sided strip detector with a strip pitch of 59 μm. The flexible nature of this system allows the application of adaptive imaging techniques. We present system details; calibration, acquisition, and reconstruction methods; and imaging results. PMID:26160983

  8. High resolution solar X-ray studies

    NASA Technical Reports Server (NTRS)

    Blake, R. L.

    1974-01-01

    Two high resolution solar X-ray payloads and their launches on Aerobee rockets with pointing system are described. The payloads included 5 to 25A X-ray spectrometers, multiaperture X-ray cameras, and command box attitude control inflight by means of a television image radioed to ground. Spatial resolution ranged from five arc minutes to ten arc seconds and spectral resolution ranged from 500 to 3000. Several laboratory tasks were completed in order to achieve the desired resolution. These included (1) development of techniques to align grid collimators, (2) studies of the spectrometric properties of crystals, (3) measurements of the absorption coefficients of various materials used in X-ray spectrometers, (4) evaluation of the performance of multiaperture cameras, and (5) development of facilities.

  9. A simple, high efficiency, high resolution spectropolarimeter

    NASA Astrophysics Data System (ADS)

    Barden, Samuel C.

    2012-09-01

    A simple concept is described that uses volume phase holographic gratings as polarizing dispersers for a high efficiency, high resolution spectropolarimeter. Although the idea has previously been mentioned in the literature as possible, such a concept has not been explored in detail. Performance analysis is presented for a VPHG spectropolarimeter concept that could be utilized for both solar and night-time astronomy. Instrumental peak efficiency can approach 100% with spectral dispersions permitting R~200,000 spectral resolution with diffraction limited telescopes. The instrument has 3-channels: two dispersed image planes with orthogonal polarization and an undispersed image plane. The concept has a range of versatility where it could be configured (with appropriate half-wave plates) for slit-fed spectroscopy or without slits for snapshot/hyperspectral/tomographic spectroscopic imaging. Multiplex gratings could also be used for the simultaneous recording of two separate spectral bands or multiple instruments could be daisy chained with beam splitters for further spectral coverage.

  10. Ecological applications of high resolution spectrometry

    NASA Technical Reports Server (NTRS)

    Lawrence, William T.

    1989-01-01

    Future directions of NASA's space program plans include a significant effort at studying the Earth as a system of interrelated ecosystems. As part of NASA's Earth Observing System (Eos) Program a series of space platforms will be launched and operated to study the Earth with a variety of active and passive instruments. Several of the Eos instruments will be capable of imaging the planet's surface reflectance on a large number of very narrow portions of the solar spectrum. After the development of appropriate algorithms, this reflectance information will be used to determine key parameters about the structure and function of terrestrial and aquatic ecosystems and the pattern and processes of those systems across large areas of the globe. Algorithm development applicable to terrestrial systems will permit the inference of ecological processes from high resolution spectrometry data, similar to that to be forthcoming from the Eos mission. The first summer was spent working with tropical soils and relating their reflectance characteristics to particle size, iron content, and color. This summer the emphasis is on vegetation and work was begun with the Forest Ecosystems Dynamics Project in the Earth Resources Branch where both optical and radar characteristics of a mixed conifer/hardwood forest in Maine are being studied for use in a ecological modeling effort. A major series of aircraft overflights will take place throughout the summer. Laboratory and field spectrometers are used to measure the spectral reflectance of a hierarchy of vegetation from individual leaves to whole canopies for eventual modeling of their nutrient content using reflectance data. Key leaf/canopy parameters are being approximated including chlorophyll, nitrogen, phosphorus, water content, and leaf specific weight using high resolution spectrometry alone. Measurements are made of carbon exchange across the landscape for input to a spatial modeling effort to gauge production within the forest. A

  11. Pyramidal fractal dimension for high resolution images.

    PubMed

    Mayrhofer-Reinhartshuber, Michael; Ahammer, Helmut

    2016-07-01

    Fractal analysis (FA) should be able to yield reliable and fast results for high-resolution digital images to be applicable in fields that require immediate outcomes. Triggered by an efficient implementation of FA for binary images, we present three new approaches for fractal dimension (D) estimation of images that utilize image pyramids, namely, the pyramid triangular prism, the pyramid gradient, and the pyramid differences method (PTPM, PGM, PDM). We evaluated the performance of the three new and five standard techniques when applied to images with sizes up to 8192 × 8192 pixels. By using artificial fractal images created by three different generator models as ground truth, we determined the scale ranges with minimum deviations between estimation and theory. All pyramidal methods (PM) resulted in reasonable D values for images of all generator models. Especially, for images with sizes ≥1024×1024 pixels, the PMs are superior to the investigated standard approaches in terms of accuracy and computation time. A measure for the possibility to differentiate images with different intrinsic D values did show not only that the PMs are well suited for all investigated image sizes, and preferable to standard methods especially for larger images, but also that results of standard D estimation techniques are strongly influenced by the image size. Fastest results were obtained with the PDM and PGM, followed by the PTPM. In terms of absolute D values best performing standard methods were magnitudes slower than the PMs. Concluding, the new PMs yield high quality results in short computation times and are therefore eligible methods for fast FA of high-resolution images.

  12. Pyramidal fractal dimension for high resolution images

    NASA Astrophysics Data System (ADS)

    Mayrhofer-Reinhartshuber, Michael; Ahammer, Helmut

    2016-07-01

    Fractal analysis (FA) should be able to yield reliable and fast results for high-resolution digital images to be applicable in fields that require immediate outcomes. Triggered by an efficient implementation of FA for binary images, we present three new approaches for fractal dimension (D) estimation of images that utilize image pyramids, namely, the pyramid triangular prism, the pyramid gradient, and the pyramid differences method (PTPM, PGM, PDM). We evaluated the performance of the three new and five standard techniques when applied to images with sizes up to 8192 × 8192 pixels. By using artificial fractal images created by three different generator models as ground truth, we determined the scale ranges with minimum deviations between estimation and theory. All pyramidal methods (PM) resulted in reasonable D values for images of all generator models. Especially, for images with sizes ≥1024 ×1024 pixels, the PMs are superior to the investigated standard approaches in terms of accuracy and computation time. A measure for the possibility to differentiate images with different intrinsic D values did show not only that the PMs are well suited for all investigated image sizes, and preferable to standard methods especially for larger images, but also that results of standard D estimation techniques are strongly influenced by the image size. Fastest results were obtained with the PDM and PGM, followed by the PTPM. In terms of absolute D values best performing standard methods were magnitudes slower than the PMs. Concluding, the new PMs yield high quality results in short computation times and are therefore eligible methods for fast FA of high-resolution images.

  13. Pyramidal fractal dimension for high resolution images.

    PubMed

    Mayrhofer-Reinhartshuber, Michael; Ahammer, Helmut

    2016-07-01

    Fractal analysis (FA) should be able to yield reliable and fast results for high-resolution digital images to be applicable in fields that require immediate outcomes. Triggered by an efficient implementation of FA for binary images, we present three new approaches for fractal dimension (D) estimation of images that utilize image pyramids, namely, the pyramid triangular prism, the pyramid gradient, and the pyramid differences method (PTPM, PGM, PDM). We evaluated the performance of the three new and five standard techniques when applied to images with sizes up to 8192 × 8192 pixels. By using artificial fractal images created by three different generator models as ground truth, we determined the scale ranges with minimum deviations between estimation and theory. All pyramidal methods (PM) resulted in reasonable D values for images of all generator models. Especially, for images with sizes ≥1024×1024 pixels, the PMs are superior to the investigated standard approaches in terms of accuracy and computation time. A measure for the possibility to differentiate images with different intrinsic D values did show not only that the PMs are well suited for all investigated image sizes, and preferable to standard methods especially for larger images, but also that results of standard D estimation techniques are strongly influenced by the image size. Fastest results were obtained with the PDM and PGM, followed by the PTPM. In terms of absolute D values best performing standard methods were magnitudes slower than the PMs. Concluding, the new PMs yield high quality results in short computation times and are therefore eligible methods for fast FA of high-resolution images. PMID:27475069

  14. Energy Resolved High Resolution Dynamic E-Cell Materials Research. Final Report

    SciTech Connect

    Carpenter, Ray; Sharma, Renu; Mayer, James

    2000-05-16

    The purpose of this project was to develop in situ materials reaction observation capability in an intermediate voltage high resolution transmission electron microscope. To accomplish this we purchased a GATAN imaging energy filter system, a hot stage, and designed and constructed an environmental cell and real time television image recording system, and installed this equipment on our EM 430 intermediate voltage electron microscope.

  15. Crusta: Visualizing High-resolution Global Data

    NASA Astrophysics Data System (ADS)

    Bernardin, T. S.; Kreylos, O.; Bowles, C. J.; Cowgill, E.; Hamann, B.; Kellogg, L. H.

    2009-12-01

    Virtual globes have become indispensable tools for visualizing, understanding and presenting data from Earth and other planetary bodies. The scientific community has invested much effort into exploiting existing globes to their fullest potential by refining and adapting their capabilities to better satisfy specific needs. For example, Google Earth provides users with the ability to view hillshade images derived from airborne LiDAR data such as the 2007 Northern California GeoEarthScope data. However, because most available globes were not designed with the specific needs of geoscientists in mind, shortcomings are becoming increasingly evident in geoscience applications such as terrain visualization. In particular, earth scientists struggle to visualize digital elevation models with both high spatial resolution (0.5 - 1 square meters per sample) and large extent (>2000 square kilometers), such as those obtained with airborne LiDAR. To address the specific earth science need of real-time terrain visualization of LiDAR data, we are developing Crusta as part of a close collaboration involving earth and computer scientists. Crusta is a new virtual globe that differs from widely used globes by both providing accurate global data representation and the ability to easily visualize custom topographic and image data. As a result, Crusta enables real-time, interactive visualization of high resolution digital elevation data spanning thousands of square kilometers, such as the complete 2007 Northern California GeoEarthScope airborne LiDAR data set. To implement an accurate data representation and avoid distortion of the display at the poles, where other projections have singularities, Crusta represents the globe as a thirty-sided polyhedron. Each side of this polyhedron can be subdivided to an arbitrarily fine grid on the surface of the globe, which allows Crusta to accommodate input data of arbitrary resolution ranging from global (e.g., Blue Marble) to local (e.g., a tripod

  16. [Application of high resolution remote sensing technology in research of schistosomiasis surveillance].

    PubMed

    Xue, Jing-bo; Zhang, Li-juan; Wang, Qiang; Lu, Yan-xin; Li, Shi-zhu

    2015-10-01

    Schistosomiasis is closely related to environmental factors, the changes of environmental factors, such as vegetation, temperature, hydrology and soil, could impact the transmission of the disease. The environmental factors associated with schistosomiasis could be extracted by remote sensing technology quickly and precisely, and be applied to monitor the schistosomiasis transmission. The studies on high resolution remote sensing technology applied in the research of schistosomiasis are reviewed in this paper.

  17. Fiber optic cable-based high-resolution, long-distance VGA extenders

    NASA Astrophysics Data System (ADS)

    Rhee, Jin-Geun; Lee, Iksoo; Kim, Heejoon; Kim, Sungjoon; Koh, Yeon-Wan; Kim, Hoik; Lim, Jiseok; Kim, Chur; Kim, Jungwon

    2013-02-01

    Remote transfer of high-resolution video information finds more applications in detached display applications for large facilities such as theaters, sports complex, airports, and security facilities. Active optical cables (AOCs) provide a promising approach for enhancing both the transmittable resolution and distance that standard copper-based cables cannot reach. In addition to the standard digital formats such as HDMI, the high-resolution, long-distance transfer of VGA format signals is important for applications where high-resolution analog video ports should be also supported, such as military/defense applications and high-resolution video camera links. In this presentation we present the development of a compressionless, high-resolution (up to WUXGA, 1920x1200), long-distance (up to 2 km) VGA extenders based on serialized technique. We employed asynchronous serial transmission and clock regeneration techniques, which enables lower cost implementation of VGA extenders by removing the necessity for clock transmission and large memory at the receiver. Two 3.125-Gbps transceivers are used in parallel to meet the required maximum video data rate of 6.25 Gbps. As the data are transmitted asynchronously, 24-bit pixel clock time stamp is employed to regenerate video pixel clock accurately at the receiver side. In parallel to the video information, stereo audio and RS-232 control signals are transmitted as well.

  18. High-resolution imaging using endoscopic holography

    NASA Astrophysics Data System (ADS)

    Bjelkhagen, Hans I.

    1990-08-01

    Endoscopic holography or endoholography combines the features of endoscopy and holography. The purpose of endoholographic imaging is to provide the physician with a unique means of extending diagnosis by providing a life-like record of tissue. Endoholographic recording will provide means for microscopic examination of tissue and in some cases may obviate the need to excise specimens for biopsy. In this method holograms which have the unique properties of three-dimensionality large focal depth and high resolution are made with a newly designed endoscope. The endoscope uses a single-mode optical fiber for illumination and single-beam reflection holograms are recorded in close contact with the tissue at the distal end of the endoscope. The holograms are viewed under a microscope. By using the proper combinations of dyes for staining specific tissue types with various wavelengths of laser illumination increased contrast on the cellular level can be obtained. Using dyes such as rose bengal in combination with the 514. 5 nm line of an argon ion laser and trypan blue or methylene blue with the 647. 1 nm line of a krypton ion laser holograms of the stained colon of a dog showed the architecture of the colon''s columnar epithelial cells. It is hoped through chronological study using this method in-vivo an increased understanding of the etiology and pathology of diseases such as Crohn''s diseases colitis proctitis and several different forms of cancer will help to their control. 1.

  19. Holographic high-resolution endoscopic image recording

    NASA Astrophysics Data System (ADS)

    Bjelkhagen, Hans I.

    1991-03-01

    Endoscopic holography or endoholography combines the features of endoscopy and holography. The purpose of endoholographic imaging is to provide the physician with a unique means of extending diagnosis by providing a life-like record of tissue. Endoholographic recording will provide means for microscopic examination of tissue and in some cases may obviate the need to excise specimens for biopsy. In this method holograms which have the unique properties of three-dimensionality large focal depth and high resolution are made with a newly designed endoscope. The endoscope uses a single-mode optical fiber for illumination and single-beam reflection holograms are recorded in close contact with the tissue at the distal end of the endoscope. The holograms are viewed under a microscope. By using the proper combinations of dyes for staining specific tissue types with various wavelengths of laser illumination increased contrast on the cellular level can be obtained. Using dyes such as rose bengal in combination with the 514. 5 nm line of an argon ion laser and trypan blue or methylene blue with the 647. 1 nm line of a krypton ion laser holograms of the stained colon of a dog showed the architecture of the colon''s columnar epithelial cells. It is hoped through chronological study using this method in-vivo an increased understanding of the etiology and pathology of diseases such as Crohn''s diseases colitis proctitis and several different forms of cancer will help

  20. High-resolution light microscopy of nanoforms

    NASA Astrophysics Data System (ADS)

    Vodyanoy, Vitaly; Pustovyy, Oleg; Vainrub, Arnold

    2007-09-01

    We developed a high resolution light imaging system. Diffraction gratings with 100 nm width lines as well as less than 100 nm size features of different-shaped objects are clearly visible on a calibrated microscope test slide (Vainrub et al., Optics Letters, 2006, 31, 2855). The two-point resolution increase results from a known narrowing of the central diffraction peak for the annular aperture. Better visibility and advanced contrast of the smallest features in the image are due to enhancement of high spatial frequencies in the optical transfer function. The imaging system is portable, low energy, and battery operated. It has been adapted to use in both transmitting and reflecting light. It is particularly applicable for motile nanoform systems where structure and functions can be depicted in real time. We have isolated micrometer and submicrometer particles, termed proteons, from human and animal blood. Proteons form by reversible seeded aggregation of proteins around proteon nucleating centers (PNCs). PNCs are comprised of 1-2nm metallic nanoclusters containing 40-300 atoms. Proteons are capable of spontaneous assembling into higher nanoform systems assuming structure of complicated topology. The arrangement of complex proteon system mimics the structure of a small biological cell. It has structures that imitate membrane and nucleolus or nuclei. Some of these nanoforms are motile. They interact and divide. Complex nanoform systems can spontaneously reduce to simple proteons. The physical properties of these nanoforms could shed some light on the properties of early life forms or forms at extreme conditions.

  1. High-resolution CCD imaging alternatives

    NASA Astrophysics Data System (ADS)

    Brown, D. L.; Acker, D. E.

    1992-08-01

    High resolution CCD color cameras have recently stimulated the interest of a large number of potential end-users for a wide range of practical applications. Real-time High Definition Television (HDTV) systems are now being used or considered for use in applications ranging from entertainment program origination through digital image storage to medical and scientific research. HDTV generation of electronic images offers significant cost and time-saving advantages over the use of film in such applications. Further in still image systems electronic image capture is faster and more efficient than conventional image scanners. The CCD still camera can capture 3-dimensional objects into the computing environment directly without having to shoot a picture on film develop it and then scan the image into a computer. 2. EXTENDING CCD TECHNOLOGY BEYOND BROADCAST Most standard production CCD sensor chips are made for broadcast-compatible systems. One popular CCD and the basis for this discussion offers arrays of roughly 750 x 580 picture elements (pixels) or a total array of approximately 435 pixels (see Fig. 1). FOR. A has developed a technique to increase the number of available pixels for a given image compared to that produced by the standard CCD itself. Using an inter-lined CCD with an overall spatial structure several times larger than the photo-sensitive sensor areas each of the CCD sensors is shifted in two dimensions in order to fill in spatial gaps between adjacent sensors.

  2. High resolution animated scenes from stills.

    PubMed

    Lin, Zhouchen; Wang, Lifeng; Wang, Yunbo; Kang, Sing Bing; Fang, Tian

    2007-01-01

    Current techniques for generating animated scenes involve either videos (whose resolution is limited) or a single image (which requires a significant amount of user interaction). In this paper, we describe a system that allows the user to quickly and easily produce a compelling-looking animation from a small collection of high resolution stills. Our system has two unique features. First, it applies an automatic partial temporal order recovery algorithm to the stills in order to approximate the original scene dynamics. The output sequence is subsequently extracted using a second-order Markov Chain model. Second, a region with large motion variation can be automatically decomposed into semiautonomous regions such that their temporal orderings are softly constrained. This is to ensure motion smoothness throughout the original region. The final animation is obtained by frame interpolation and feathering. Our system also provides a simple-to-use interface to help the user to fine-tune the motion of the animated scene. Using our system, an animated scene can be generated in minutes. We show results for a variety of scenes. PMID:17356221

  3. High-resolution microwave images of Saturn

    NASA Technical Reports Server (NTRS)

    Grossman, A. W.; Muhleman, D. O.; Berge, G. L.

    1989-01-01

    An analysis of high-resolution microwave images of Saturn and Saturn's individual rings is presented. Radio interferometric observations of Saturn taken at the Very Large Array in New Mexico at wavelengths of 2 and 6 centimeters reveal interesting new features in both the atmosphere and rings. The resulting maps show an increase in brightness temperature of about 3 K from equator to pole at both wavelengths, while the 6-centimeter map shows a bright band at northern midlatitudes. The data are consistent with a radiative transfer model of the atmosphere that constrains the well-mixed, fully saturated, NH3 mixing ratio to be 0.00012 in a region just below the NH3 clouds, while the observed bright band indicates a 25 percent relative decrease of NH3 in northern midlatitudes. Brightness temperatures for the classical rings are presented. Ring brightness shows a variation with azimuth and is linearly polarized at an average value of about 5 percent. The variations in ring polarization suggest that at least 20 percent of the ring brightness is the result of a single scattering process.

  4. Laser wavelength comparison by high resolution interferometry.

    PubMed

    Layer, H P; Deslattes, R D; Schweitzer, W G

    1976-03-01

    High resolution interferometry has been used to determine the wavelength ratio between two molecularly stabilized He-Ne lasers, one locked to a methane absorption at 3.39 microm and the other locked to the k peak of (129)I(2) at 633 nm. An optical beat frequency technique gave fractional orders while a microwave sideband method yielded the integer parts. Conventional (third derivative) peak seeking servoes stabilized both laser and cavity lengths. Reproducibility of the electronic control system and optics was a few parts in 10(12), while systematic errors associated with curvature of the cavity mirrors limited the accuracy of the wavelength ratio measurement to 2 parts in 10(10). The measured wavelength ratio of the methane stabilized He-Ne laser at 3.39 microm [P(7) line, nu(3) band] to the (129)I(2) (k peak) stabilized He-Ne laser at 633 nm was 5.359 049 260 6 (0.000 2 ppm). This ratio agrees with that calculated from the (lower accuracy) results of earlier wavelength measurements made relative to the (86)Kr standard. Its higher accuracy thus permits a provisional extension of the frequency scale based on the cesium oscillator into the visible spectrum.

  5. High-resolution microwave images of saturn.

    PubMed

    Grossman, A W; Muhleman, D O; Berge, G L

    1989-09-15

    An analysis of high-resolution microwave images of Saturn and Saturn's individual rings is presented. Radio interferometric observations of Saturn taken at the Very Large Array in New Mexico at wavelengths of 2 and 6 centimeters reveal interesting new features in both the atmosphere and rings. The resulting maps show an increase in brightness temperature of about 3 K from equator to pole at both wavelengths, while the 6-centimeter map shows a bright band at northern mid-latitudes. The data are consistent with a radiative transfer model of the atmosphere that constrains the well-mixed, fully saturated, NH(3) mixing ratio to be 1.2 x 10(-4) in a region just below the NH(3) clouds, while the observed bright band indicates a 25 percent relative decrease of NH(3) in northern mid-latitudes. Brightness temperatures for the classical rings are presented. Ring brightness shows a variation with azimuth and is linearly polarized at an average value of about 5 percent. The variations in ring polarization suggest that at least 20 percent of the ring brightness is the result of a single scattering process.

  6. Potential High Resolution Dosimeters For MRT

    NASA Astrophysics Data System (ADS)

    Bräuer-Krisch, E.; Rosenfeld, A.; Lerch, M.; Petasecca, M.; Akselrod, M.; Sykora, J.; Bartz, J.; Ptaszkiewicz, M.; Olko, P.; Berg, A.; Wieland, M.; Doran, S.; Brochard, T.; Kamlowski, A.; Cellere, G.; Paccagnella, A.; Siegbahn, E. A.; Prezado, Y.; Martinez-Rovira, I.; Bravin, A.; Dusseau, L.; Berkvens, P.

    2010-07-01

    Microbeam Radiation Therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600 keV, produced by 2nd and 3rd generation synchrotron sources, such as the National Synchrotron Light Source (NSLS) in the U.S., and the European Synchrotron Radiation Facility (ESRF) in France, respectively. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. A small beam divergence and a filtered white beam spectrum in the energy range between 30 and 250 keV results in the advantage of steep dose gradients with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has allowed a vast number of results from preclinical trials on different animal models, including mice, rats, piglets and rabbits. Microbeams in the range between 10 and 100 micron width show an unprecedented sparing of normal radiosensitive tissues as well as preferential damage to malignant tumor tissues. Typically, MRT uses arrays of narrow (˜25-100 micron-wide) microplanar beams separated by wider (100-400 microns centre-to-centre, c-t-c) microplanar spaces. We note that thicker microbeams of 0.1-0.68 mm used by investigators at the NSLS are still called microbeams, although some invesigators in the community prefer to call them minibeams. This report, however, limits it discussion to 25-100 μm microbeams. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues. High resolution dosimetry has been developed over the last two decades, but typical dose ranges are adapted to dose delivery in conventional Radiation Therapy (RT). Spatial resolution in the sub-millimetric range has been achieved, which is currently required for quality assurance measurements in Gamma-knife RT. Most typical commercially available detectors are not suitable for MRT applications at a dose rate of 16000 Gy/s, micron

  7. Large Scale, High Resolution, Mantle Dynamics Modeling

    NASA Astrophysics Data System (ADS)

    Geenen, T.; Berg, A. V.; Spakman, W.

    2007-12-01

    To model the geodynamic evolution of plate convergence, subduction and collision and to allow for a connection to various types of observational data, geophysical, geodetical and geological, we developed a 4D (space-time) numerical mantle convection code. The model is based on a spherical 3D Eulerian fem model, with quadratic elements, on top of which we constructed a 3D Lagrangian particle in cell(PIC) method. We use the PIC method to transport material properties and to incorporate a viscoelastic rheology. Since capturing small scale processes associated with localization phenomena require a high resolution, we spend a considerable effort on implementing solvers suitable to solve for models with over 100 million degrees of freedom. We implemented Additive Schwartz type ILU based methods in combination with a Krylov solver, GMRES. However we found that for problems with over 500 thousend degrees of freedom the convergence of the solver degraded severely. This observation is known from the literature [Saad, 2003] and results from the local character of the ILU preconditioner resulting in a poor approximation of the inverse of A for large A. The size of A for which ILU is no longer usable depends on the condition of A and on the amount of fill in allowed for the ILU preconditioner. We found that for our problems with over 5×105 degrees of freedom convergence became to slow to solve the system within an acceptable amount of walltime, one minute, even when allowing for considerable amount of fill in. We also implemented MUMPS and found good scaling results for problems up to 107 degrees of freedom for up to 32 CPU¡¯s. For problems with over 100 million degrees of freedom we implemented Algebraic Multigrid type methods (AMG) from the ML library [Sala, 2006]. Since multigrid methods are most effective for single parameter problems, we rebuild our model to use the SIMPLE method in the Stokes solver [Patankar, 1980]. We present scaling results from these solvers for 3D

  8. Potential High Resolution Dosimeters For MRT

    SciTech Connect

    Braeuer-Krisch, E.; Brochard, T.; Prezado, Y.; Bravin, A.; Berkvens, P.; Rosenfeld, A.; Lerch, M.; Petasecca, M.; Akselrod, M.; Sykora, J.; Bartz, J.; Ptaszkiewicz, M.; Olko, P.; Berg, A.; Wieland, M.; Doran, S.; Kamlowski, A.; Cellere, G.

    2010-07-23

    Microbeam Radiation Therapy (MRT) uses highly collimated, quasi-parallel arrays of X-ray microbeams of 50-600 keV, produced by 2nd and 3rd generation synchrotron sources, such as the National Synchrotron Light Source (NSLS) in the U.S., and the European Synchrotron Radiation Facility (ESRF) in France, respectively. High dose rates are necessary to deliver therapeutic doses in microscopic volumes, to avoid spreading of the microbeams by cardiosynchronous movement of the tissues. A small beam divergence and a filtered white beam spectrum in the energy range between 30 and 250 keV results in the advantage of steep dose gradients with a sharper penumbra than that produced in conventional radiotherapy. MRT research over the past 20 years has allowed a vast number of results from preclinical trials on different animal models, including mice, rats, piglets and rabbits. Microbeams in the range between 10 and 100 micron width show an unprecedented sparing of normal radiosensitive tissues as well as preferential damage to malignant tumor tissues. Typically, MRT uses arrays of narrow ({approx}25-100 micron-wide) microplanar beams separated by wider (100-400 microns centre-to-centre, c-t-c) microplanar spaces. We note that thicker microbeams of 0.1-0.68 mm used by investigators at the NSLS are still called microbeams, although some invesigators in the community prefer to call them minibeams. This report, however, limits it discussion to 25-100 {mu}m microbeams. Peak entrance doses of several hundreds of Gy are surprisingly well tolerated by normal tissues. High resolution dosimetry has been developed over the last two decades, but typical dose ranges are adapted to dose delivery in conventional Radiation Therapy (RT). Spatial resolution in the sub-millimetric range has been achieved, which is currently required for quality assurance measurements in Gamma-knife RT. Most typical commercially available detectors are not suitable for MRT applications at a dose rate of 16000 Gy

  9. High-Resolution Radar Imagery of Mars

    NASA Astrophysics Data System (ADS)

    Harmon, John K.; Nolan, M. C.

    2009-09-01

    We present high-resolution radar images of Mars obtained during the 2005 and 2007 oppositions. The images were constructed from long-code delay-Doppler observations made with the Arecibo S-band (13-cm) radar. The average image resolution of 3 km represented a better than order-of-magnitude improvement over pre-upgrade Arecibo imagery of the planet. Images of depolarized reflectivity (an indicator primarily of wavelength-scale surface roughness) show the same bright volcanic flow features seen in earlier imagery, but with much finer detail. A new image of the Elysium region shows fine detail in the radar-bright channels of Athabasca Vallis, Marte Vallis, and Grjota Vallis. The new images of Tharsis and Olympus Mons also show a complex array of radar-bright and radar-dark features. Southern Amazonis exhibits some of the most complex and puzzling radar-bright structure on the planet. Another curiosity is the Chryse/Xanthe/Channels region, where we find some radar-bright features in or adjacent to fluvial chaos structures. Chryse/Xanthe is also the only region of Mars showing radar-bright craters (which are rare on Mars but common on the Moon and Mercury). We also obtained the first delay-Doppler image showing the enhanced backscatter from the residual south polar ice cap. In addition to the depolarized imagery, we were able to make the first delay-Doppler images of the circular polarization ratio (an important diagnostic for surface roughness texture). We find that vast areas of the radar-bright volcanic regions have polarization ratios close to unity. Such high ratios are rare for terrestrial lava flows and only seen for extremely blocky surfaces giving high levels of multiple scattering.

  10. Toward high-resolution optoelectronic retinal prosthesis

    NASA Astrophysics Data System (ADS)

    Palanker, Daniel; Huie, Philip; Vankov, Alexander; Asher, Alon; Baccus, Steven

    2005-04-01

    It has been already demonstrated that electrical stimulation of retina can produce visual percepts in blind patients suffering from macular degeneration and retinitis pigmentosa. Current retinal implants provide very low resolution (just a few electrodes), while several thousand pixels are required for functional restoration of sight. We present a design of the optoelectronic retinal prosthetic system that can activate a retinal stimulating array with pixel density up to 2,500 pix/mm2 (geometrically corresponding to a visual acuity of 20/80), and allows for natural eye scanning rather than scanning with a head-mounted camera. The system operates similarly to "virtual reality" imaging devices used in military and medical applications. An image from a video camera is projected by a goggle-mounted infrared LED-LCD display onto the retina, activating an array of powered photodiodes in the retinal implant. Such a system provides a broad field of vision by allowing for natural eye scanning. The goggles are transparent to visible light, thus allowing for simultaneous utilization of remaining natural vision along with prosthetic stimulation. Optical control of the implant allows for simple adjustment of image processing algorithms and for learning. A major prerequisite for high resolution stimulation is the proximity of neural cells to the stimulation sites. This can be achieved with sub-retinal implants constructed in a manner that directs migration of retinal cells to target areas. Two basic implant geometries are described: perforated membranes and protruding electrode arrays. Possibility of the tactile neural stimulation is also examined.

  11. Decadal prediction with a high resolution model

    NASA Astrophysics Data System (ADS)

    Monerie, Paul-Arthur; Valcke, Sophie; Terray, Laurent; Moine, Marie-Pierre

    2016-04-01

    The ability of a high resolution coupled atmosphere-ocean general circulation model (with a horizontal resolution of the quarter degree in the ocean and of about 50 km in the atmosphere) to predict the annual means of temperature, precipitation, sea-ice volume and extent is assessed. Reasonable skill in predicting sea surface temperatures and surface air temperature is obtained, especially over the North Atlantic, the tropical Atlantic and the Indian Ocean. The skill in predicting precipitations is weaker and not significant. The Sea Ice Extent and volume are also reasonably predicted in winter (March) and summer (September). It is however argued that the skill is mainly due to the atmosphere feeding in well-mixed GHGs. The mid-90's subpolar gyre warming is assessed. The model simulates a warming of the North Atlantic Ocean, associated with an increase of the meridional heat transport, a strengthening of the North Atlantic current and a deepening of the mixed layer over the Labrador Sea. The atmosphere plays a role in the warming through a modulation of the North Atlantic Oscillation and a shrinking of the subpolar gyre. At the 3-8 years lead-time, a negative anomaly of pressure, located south of the subpolar gyre is associated with the wind speed decrease over the subpolar gyre. It prevents oceanic heat-loss and favors the northward move, from the subtropical to the subpolar gyre, of anomalously warm and salty water, leading to its warming. We finally argued that the subpolar gyre warming is triggered by the ocean dynamic but the atmosphere can contributes to its sustaining. This work is realised in the framework of the EU FP7 SPECS Project.

  12. High-resolution phylogenetic microbial community profiling

    SciTech Connect

    Singer, Esther; Coleman-Derr, Devin; Bowman, Brett; Schwientek, Patrick; Clum, Alicia; Copeland, Alex; Ciobanu, Doina; Cheng, Jan-Fang; Gies, Esther; Hallam, Steve; Tringe, Susannah; Woyke, Tanja

    2014-03-17

    The representation of bacterial and archaeal genome sequences is strongly biased towards cultivated organisms, which belong to merely four phylogenetic groups. Functional information and inter-phylum level relationships are still largely underexplored for candidate phyla, which are often referred to as microbial dark matter. Furthermore, a large portion of the 16S rRNA gene records in the GenBank database are labeled as environmental samples and unclassified, which is in part due to low read accuracy, potential chimeric sequences produced during PCR amplifications and the low resolution of short amplicons. In order to improve the phylogenetic classification of novel species and advance our knowledge of the ecosystem function of uncultivated microorganisms, high-throughput full length 16S rRNA gene sequencing methodologies with reduced biases are needed. We evaluated the performance of PacBio single-molecule real-time (SMRT) sequencing in high-resolution phylogenetic microbial community profiling. For this purpose, we compared PacBio and Illumina metagenomic shotgun and 16S rRNA gene sequencing of a mock community as well as of an environmental sample from Sakinaw Lake, British Columbia. Sakinaw Lake is known to contain a large age of microbial species from candidate phyla. Sequencing results show that community structure based on PacBio shotgun and 16S rRNA gene sequences is highly similar in both the mock and the environmental communities. Resolution power and community representation accuracy from SMRT sequencing data appeared to be independent of GC content of microbial genomes and was higher when compared to Illumina-based metagenome shotgun and 16S rRNA gene (iTag) sequences, e.g. full-length sequencing resolved all 23 OTUs in the mock community, while iTags did not resolve closely related species. SMRT sequencing hence offers various potential benefits when characterizing uncharted microbial communities.

  13. High Resolution Global View of Io

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Io, the most volcanic body in the solar system is seen in the highest resolution obtained to date by NASA's Galileo spacecraft. The smallest features that can be discerned are 2.5 kilometers in size. There are rugged mountains several kilometers high, layered materials forming plateaus, and many irregular depressions called volcanic calderas. Several of the dark, flow-like features correspond to hot spots, and may be active lava flows. There are no landforms resembling impact craters, as the volcanism covers the surface with new deposits much more rapidly than the flux of comets and asteroids can create large impact craters. The picture is centered on the side of Io that always faces away from Jupiter; north is to the top.

    Color images acquired on September 7, 1996 have been merged with higher resolution images acquired on November 6, 1996 by the Solid State Imaging (CCD) system aboard NASA's Galileo spacecraft. The color is composed of data taken, at a range of 487,000 kilometers, in the near-infrared, green, and violet filters and has been enhanced to emphasize the extraordinary variations in color and brightness that characterize Io's face. The high resolution images were obtained at ranges which varied from 245,719 kilometers to 403,100 kilometers.

    Launched in October 1989, Galileo entered orbit around Jupiter on December 7, 1995. The spacecraft's mission is to conduct detailed studies of the giant planet, its largest moons and the Jovian magnetic environment. The Jet Propulsion Laboratory, Pasadena, CA manages the mission for NASA's Office of Space Science, Washington, DC.

    This image and other images and data received from Galileo are posted on the World Wide Web, on the Galileo mission home page at URL http://galileo.jpl.nasa.gov. Background information and educational context for the images can be found at URL http://www.jpl.nasa.gov/galileo/sepo

  14. Quantitative atom column position analysis at the incommensurate interfaces of a (PbS)(1.14)NbS(2) misfit layered compound with aberration-corrected HRTEM.

    PubMed

    Garbrecht, M; Spiecker, E; Tillmann, K; Jäger, W

    2011-02-01

    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)(1.14)NbS(2) 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 ±6pm. 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.

  15. High Resolution Airborne Shallow Water Mapping

    NASA Astrophysics Data System (ADS)

    Steinbacher, F.; Pfennigbauer, M.; Aufleger, M.; Ullrich, A.

    2012-07-01

    In order to meet the requirements of the European Water Framework Directive (EU-WFD), authorities face the problem of repeatedly performing area-wide surveying of all kinds of inland waters. Especially for mid-sized or small rivers this is a considerable challenge imposing insurmountable logistical efforts and costs. It is therefore investigated if large-scale surveying of a river system on an operational basis is feasible by employing airborne hydrographic laser scanning. In cooperation with the Bavarian Water Authority (WWA Weilheim) a pilot project was initiated by the Unit of Hydraulic Engineering at the University of Innsbruck and RIEGL Laser Measurement Systems exploiting the possibilities of a new LIDAR measurement system with high spatial resolution and high measurement rate to capture about 70 km of riverbed and foreland for the river Loisach in Bavaria/Germany and the estuary and parts of the shoreline (about 40km in length) of lake Ammersee. The entire area surveyed was referenced to classic terrestrial cross-section surveys with the aim to derive products for the monitoring and managing needs of the inland water bodies forced by the EU-WFD. The survey was performed in July 2011 by helicopter and airplane and took 3 days in total. In addition, high resolution areal images were taken to provide an optical reference, offering a wide range of possibilities on further research, monitoring, and managing responsibilities. The operating altitude was about 500 m to maintain eye-safety, even for the aided eye, the airspeed was about 55 kts for the helicopter and 75 kts for the aircraft. The helicopter was used in the alpine regions while the fixed wing aircraft was used in the plains and the urban area, using appropriate scan rates to receive evenly distributed point clouds. The resulting point density ranged from 10 to 25 points per square meter. By carefully selecting days with optimum water quality, satisfactory penetration down to the river bed was achieved

  16. High Resolution Velocity Structure in Eastern Turkey

    SciTech Connect

    Pasyanos, M; Gok, R; Zor, E; Walter, W

    2004-09-03

    We investigate the crustal and upper mantle structure of eastern Turkey where the Anatolian, Arabian and Eurasian Plates meet and form a complex tectonic structure. The Bitlis suture is a continental collision zone between the Anatolian plateau and the Arabian plate. Broadband data available through the Eastern Turkey Seismic Experiment (ETSE) provided a unique opportunity for studying the high resolution velocity structure. Zor et al. found an average 46 km thick crust in Anatolian plateau using six-layered grid search inversion of the ETSE receiver functions. Receiver functions are sensitive to the velocity contrast of interfaces and the relative travel time of converted and reverberated waves between those interfaces. The interpretation of receiver function alone with many-layered parameterization may result in an apparent depth-velocity tradeoff. In order to improve previous velocity model, we employed the joint inversion method with many layered parameterization of Julia et al. (2000) to the ETSE receiver functions. In this technique, the receiver function and surface-wave observations are combined into a single algebraic equation and each data set is weighted by an estimate of the uncertainty in the observations. We consider azimuthal changes of receiver functions and have stacked them into different groups. We calculated the receiver functions using iterative time-domain deconvolution technique and surface wave group velocity dispersion curves between 10-100 sec. We are making surface wave dispersion measurements at the ETSE stations and have incorporated them into a regional group velocity model. Preliminary results indicate a strong trend in the long period group velocity in the northeast. This indicates slow upper mantle velocities in the region consistent with Pn, Sn and receiver function results. We started with both the 1-D model that is obtained with the 12 tones dam explosion shot data recorded by ETSE network and the existing receiver function

  17. The HFIP High Resolution Hurricane Forecast Test

    NASA Astrophysics Data System (ADS)

    Nance, L. B.; Bernardet, L.; Bao, S.; Brown, B.; Carson, L.; Fowler, T.; Halley Gotway, J.; Harrop, C.; Szoke, E.; Tollerud, E. I.; Wolff, J.; Yuan, H.

    2010-12-01

    Tropical cyclones are a serious concern for the nation, causing significant risk to life, property and economic vitality. The National Oceanic and Atmospheric Administration (NOAA) National Weather Service has a mission of issuing tropical cyclone forecasts and warnings, aimed at protecting life and property and enhancing the national economy. In the last 10 years, the errors in hurricane track forecasts have been reduced by about 50% through improved model guidance, enhanced observations, and forecaster expertise. However, little progress has been made during this period toward reducing forecasted intensity errors. To address this shortcoming, NOAA established the Hurricane Forecast Improvement Project (HFIP) in 2007. HFIP is a 10-year plan to improve one to five day tropical cyclone forecasts, with a focus on rapid intensity change. Recent research suggests that prediction models with grid spacing less than 1 km in the inner core of the hurricane may provide a substantial improvement in intensity forecasts. The 2008-09 staging of the High Resolution Hurricane (HRH) Test focused on quantifying the impact of increased horizontal resolution in numerical models on hurricane intensity forecasts. The primary goal of this test was an evaluation of the effect of increasing horizontal resolution within a given model across a variety of storms with different intensity, location and structure. The test focused on 69 retrospectives cases from the 2005 and 2007 hurricane seasons. Six modeling groups participated in the HRH test utilizing a variety of models, including three configurations of the Weather Research and Forecasting (WRF) model, the operational GFDL model, the Navy’s tropical cyclone model, and a model developed at the University of Wisconsin-Madison (UWM). The Development Testbed Center (DTC) was tasked with providing objective verification statistics for a variety of metrics. This presentation provides an overview of the HRH Test and a summary of the standard

  18. Phase contrast in high resolution electron microscopy

    DOEpatents

    Rose, H.H.

    1975-09-23

    This patent relates to a device for developing a phase contrast signal for a scanning transmission electron microscope. The lens system of the microscope is operated in a condition of defocus so that predictable alternate concentric regions of high and low electron density exist in the cone of illumination. Two phase detectors are placed beneath the object inside the cone of illumination, with the first detector having the form of a zone plate, each of its rings covering alternate regions of either higher or lower electron density. The second detector is so configured that it covers the regions of electron density not covered by the first detector. Each detector measures the number of electrons incident thereon and the signal developed by the first detector is subtracted from the signal developed by the record detector to provide a phase contrast signal. (auth)

  19. The TIROS-N high resolution infrared radiation sounder

    NASA Technical Reports Server (NTRS)

    Koenig, E. W.

    1979-01-01

    The high-resolution infrared radiation sounder (HIRS/2) was developed and flown on the Television and Infrared Observation Satellite, N Series (TIROS-N) as one means of obtaining atmospheric vertical profile information. The HIRS/2 receives visible and infrared spectrum radiation through a single telescope and selects 20 narrow spectral channels by means of a rotating filter wheel. A passive radiant cooler provides an operating temperature of 106.7K for the HgCdTe and InSb detectors while the visible detector operates at instrument frame temperature. Low noise amplifiers and digital processing provide 13 bit data for spacecraft data multiplexing and transmission. The qualities of system performance that determine sounding capability are the dynamic range of data collection, the noise equivalent radiance of the system, the registration of the air columns sampled in each channel, and the ability to upgrade the calibration of the instrument to maintain the performance standard throughout life. The basic performance of the instrument in test is described. Early orbital information from the TIROS-N launched on October 13, 1978 are given and some observations on system quality are made.

  20. Specimen Preparation for High-Resolution Cryo-EM.

    PubMed

    Passmore, L A; Russo, C J

    2016-01-01

    Imaging a material with electrons at near-atomic resolution requires a thin specimen that is stable in the vacuum of the transmission electron microscope. For biological samples, this comprises a thin layer of frozen aqueous solution containing the biomolecular complex of interest. The process of preparing a high-quality specimen is often the limiting step in the determination of structures by single-particle electron cryomicroscopy (cryo-EM). Here, we describe a systematic approach for going from a purified biomolecular complex in aqueous solution to high-resolution electron micrographs that are suitable for 3D structure determination. This includes a series of protocols for the preparation of vitrified specimens on various supports, including all-gold and graphene. We also describe techniques for troubleshooting when a preparation fails to yield suitable specimens, and common mistakes to avoid during each part of the process. Finally, we include recommendations for obtaining the highest quality micrographs from prepared specimens with current microscope, detector, and support technology. PMID:27572723

  1. High resolution ultraviolet imaging spectrometer for latent image analysis.

    PubMed

    Lyu, Hang; Liao, Ningfang; Li, Hongsong; Wu, Wenmin

    2016-03-21

    In this work, we present a close-range ultraviolet imaging spectrometer with high spatial resolution, and reasonably high spectral resolution. As the transmissive optical components cause chromatic aberration in the ultraviolet (UV) spectral range, an all-reflective imaging scheme is introduced to promote the image quality. The proposed instrument consists of an oscillating mirror, a Cassegrain objective, a Michelson structure, an Offner relay, and a UV enhanced CCD. The finished spectrometer has a spatial resolution of 29.30μm on the target plane; the spectral scope covers both near and middle UV band; and can obtain approximately 100 wavelength samples over the range of 240~370nm. The control computer coordinates all the components of the instrument and enables capturing a series of images, which can be reconstructed into an interferogram datacube. The datacube can be converted into a spectrum datacube, which contains spectral information of each pixel with many wavelength samples. A spectral calibration is carried out by using a high pressure mercury discharge lamp. A test run demonstrated that this interferometric configuration can obtain high resolution spectrum datacube. The pattern recognition algorithm is introduced to analyze the datacube and distinguish the latent traces from the base materials. This design is particularly good at identifying the latent traces in the application field of forensic imaging.

  2. The structure of dodecagonal (Ta,V){sub 1.6}Te imaged by phase-contrast scanning transmission electron microscopy

    SciTech Connect

    Krumeich, F.; Mueller, E.; Wepf, R.A.; Conrad, M.; Reich, C.; Harbrecht, B.; Nesper, R.

    2012-10-15

    While HRTEM is the well-established method to characterize the structure of dodecagonal tantalum (vanadium) telluride quasicrystals and their periodic approximants, phase-contrast imaging performed on an aberration-corrected scanning transmission electron microscope (STEM) represents a favorable alternative. The (Ta,V){sub 151}Te{sub 74} clusters, the basic structural unit in all these phases, can be visualized with high resolution. A dependence of the image contrast on defocus and specimen thickness has been observed. In thin areas, the projected crystal potential is basically imaged with either dark or bright contrast at two defocus values close to Scherzer defocus as confirmed by image simulations utilizing the principle of reciprocity. Models for square-triangle tilings describing the arrangement of the basic clusters can be derived from such images. - Graphical abstract: PC-STEM image of a (Ta,V){sub 151}Te{sub 74} cluster. Highlights: Black-Right-Pointing-Pointer C{sub s}-corrected STEM is applied for the characterization of dodecagonal quasicrystals. Black-Right-Pointing-Pointer The projected potential of the structure is mirrored in the images. Black-Right-Pointing-Pointer Phase-contrast STEM imaging depends on defocus and thickness. Black-Right-Pointing-Pointer For simulations of phase-contrast STEM images, the reciprocity theorem is applicable.

  3. High-resolution ground-based spectroscopy: where and how ?

    NASA Astrophysics Data System (ADS)

    Pallavicini, R.

    2002-07-01

    An overview is presented of high-resolution optical spectrographs in operation or under development at large telescopes, with emphasis on those facilities best suited for the study of late-type stars and stellar surface inhomogeneities. Plans for the development of new high-resolution spectroscopic instruments are discussed with emphasis on the ICE spectrograph for the PEPSI spectropolarimeter at the LBT.

  4. ASIC-enabled High Resolution Optical Time Domain Reflectometer

    NASA Astrophysics Data System (ADS)

    Skendzic, Sandra

    Fiber optics has become the preferred technology in communication systems because of what it has to offer: high data transmission rates, immunity to electromagnetic interference, and lightweight, flexible cables. An optical time domain reflectometer (OTDR) provides a convenient method of locating and diagnosing faults (e.g. break in a fiber) along a fiber that can obstruct crucial optical pathways. Both the ability to resolve the precise location of the fault and distinguish between two discrete, closely spaced faults are figures of merit. This thesis presents an implementation of a high resolution OTDR through the use of a compact and programmable ASIC (application specific integrated circuit). The integration of many essential OTDR functions on a single chip is advantageous over existing commercial instruments because it enables small, lightweight packaging, and offers low power and cost efficiency. Furthermore, its compactness presents the option of placing multiple ASICs in parallel, which can conceivably ease the characterization of densely populated fiber optic networks. The OTDR ASIC consists of a tunable clock, pattern generator, precise timer, electrical receiver, and signal sampling circuit. During OTDR operation, the chip generates narrow electrical pulse, which can then be converted to optical format when coupled with an external laser diode driver. The ASIC also works with an external photodetector to measure the timing and amplitude of optical reflections in a fiber. It has a 1 cm sampling resolution, which allows for a 2 cm spatial resolution. While this OTDR ASIC has been previously demonstrated for multimode fiber fault diagnostics, this thesis focuses on extending its functionality to single mode fiber. To validate this novel approach to OTDR, this thesis is divided into five chapters: (1) introduction, (2) implementation, (3), performance of ASIC-based OTDR, (4) exploration in optical pre-amplification with a semiconductor optical amplifier, and

  5. A high resolution global scale groundwater model

    NASA Astrophysics Data System (ADS)

    de Graaf, I. E. M.; Sutanudjaja, E. H.; van Beek, L. P. H.; Bierkens, M. F. P.

    2014-05-01

    Groundwater is the world's largest accessible source of fresh water. It plays a vital role in satisfying needs for drinking water, agriculture and industrial activities. During times of drought groundwater sustains baseflow to rivers and wetlands, thereby supporting ecosystems. Most global scale hydrological models (GHMs) do not include a groundwater flow component, mainly due to lack of geohydrological data at the global scale. For the simulation of lateral flow and groundwater head dynamics a realistic physical representation of the groundwater system is needed, especially for GHMs that run at finer resolution. In this study we present a global scale groundwater model (run at 6' as dynamic steady state) using MODFLOW to construct an equilibrium water table at its natural state as the result of long-term climatic forcing. The aquifer schematization and properties were based on available global datasets of lithology and transmissivities combined with estimated aquifer thickness of an upper unconfined aquifer. The model is forced with outputs from the land-surface model PCR-GLOBWB, specifically with net recharge and surface water levels. A sensitivity analysis, in which the model was run with various parameter settings, showed variation in saturated conductivity causes most of the groundwater level variations. Simulated groundwater heads were validated against reported piezometer observations. The validation showed that groundwater depths are reasonably well simulated for many regions of the world, especially for sediment basins (R2 = 0.95). The simulated regional scale groundwater patterns and flowpaths confirm the relevance of taking lateral groundwater flow into account in GHMs. Flowpaths show inter-basin groundwater flow that can be a significant part of a basins water budget and helps to sustain river baseflow, explicitly during times of droughts. Also important aquifer systems are recharged by inter-basin groundwater flows that positively affect water

  6. High-Resolution Analytical Electron Microscopy Characterization of Corrosion and Cracking at Buried Interfaces

    SciTech Connect

    Bruemmer, Stephen M.; Thomas, Larry E.

    2001-07-01

    Recent results are presented demonstrating the application of cross-sectional analytical transmission electron microscopy (ATEM) to corrosion and cracking in high-temperature water environments. Microstructural, chemical and crystallographic characterization of buried interfaces at near-atomic resolutions is shown to reveal evidence for unexpected local environments, corrosion reactions and material transformations. Information obtained by a wide variety of high-resolution imaging and analysis methods indicates the processes occurring during crack advance and provides insights into the mechanisms controlling environmental degradation.

  7. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics.

    PubMed

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-06-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery.

  8. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics.

    PubMed

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-06-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery. PMID:23761849

  9. Lowered threshold energy for femtosecond laser induced optical breakdown in a water based eye model by aberration correction with adaptive optics

    PubMed Central

    Hansen, Anja; Géneaux, Romain; Günther, Axel; Krüger, Alexander; Ripken, Tammo

    2013-01-01

    In femtosecond laser ophthalmic surgery tissue dissection is achieved by photodisruption based on laser induced optical breakdown. In order to minimize collateral damage to the eye laser surgery systems should be optimized towards the lowest possible energy threshold for photodisruption. However, optical aberrations of the eye and the laser system distort the irradiance distribution from an ideal profile which causes a rise in breakdown threshold energy even if great care is taken to minimize the aberrations of the system during design and alignment. In this study we used a water chamber with an achromatic focusing lens and a scattering sample as eye model and determined breakdown threshold in single pulse plasma transmission loss measurements. Due to aberrations, the precise lower limit for breakdown threshold irradiance in water is still unknown. Here we show that the threshold energy can be substantially reduced when using adaptive optics to improve the irradiance distribution by spatial beam shaping. We found that for initial aberrations with a root-mean-square wave front error of only one third of the wavelength the threshold energy can still be reduced by a factor of three if the aberrations are corrected to the diffraction limit by adaptive optics. The transmitted pulse energy is reduced by 17% at twice the threshold. Furthermore, the gas bubble motions after breakdown for pulse trains at 5 kilohertz repetition rate show a more transverse direction in the corrected case compared to the more spherical distribution without correction. Our results demonstrate how both applied and transmitted pulse energy could be reduced during ophthalmic surgery when correcting for aberrations. As a consequence, the risk of retinal damage by transmitted energy and the extent of collateral damage to the focal volume could be minimized accordingly when using adaptive optics in fs-laser surgery. PMID:23761849

  10. High resolution airborne geophysics at hazardous waste disposal sites

    SciTech Connect

    Beard, L.P.; Nyquist, J.E.; Doll, W.E.; Chong Foo, M.; Gamey, T.J.

    1995-06-01

    In 1994, a high resolution helicopter geophysical survey was conducted over portions of the Oak Ridge Reservation, Tennessee. The 1800 line kilometer survey included multi-frequency electromagnetic and magnetic sensors. The areas covered by the high resolution portion of the survey were selected on the basis of their importance to the environmental restoration effort and on data obtained from the reconnaissance phase of the airborne survey in which electromagnetic, magnetic, and radiometric data were collected over the entire Oak Ridge Reservation in 1992--1993. The high resolution phase had lower sensor heights, more and higher EM frequencies, and tighter line spacings than did the reconnaissance survey. When flying over exceptionally clear areas, the high resolution bird came within a few meters of the ground surface. Unfortunately, even sparse trees and power or phone lines could prevent the bird from being towed safely at low altitude, and over such areas it was more usual for it to be flown at about the same altitude as the bird in the reconnaissance survey, about 30m. Even so, the magnetometers used in the high resolution phase were 20m closer to the ground than in the reconnaissance phase because they were mounted on the tail of the bird rather than on the tow cable above the bird. The EM frequencies used in the high resolution survey ranged from 7400Hz to 67000Hz. Only the horizontal coplanar loop configuration was used in the high resolution flyovers.

  11. Wide-Field-of-View, High-Resolution, Stereoscopic Imager

    NASA Technical Reports Server (NTRS)

    Prechtl, Eric F.; Sedwick, Raymond J.

    2010-01-01

    A device combines video feeds from multiple cameras to provide wide-field-of-view, high-resolution, stereoscopic video to the user. The prototype under development consists of two camera assemblies, one for each eye. One of these assemblies incorporates a mounting structure with multiple cameras attached at offset angles. The video signals from the cameras are fed to a central processing platform where each frame is color processed and mapped into a single contiguous wide-field-of-view image. Because the resolution of most display devices is typically smaller than the processed map, a cropped portion of the video feed is output to the display device. The positioning of the cropped window will likely be controlled through the use of a head tracking device, allowing the user to turn his or her head side-to-side or up and down to view different portions of the captured image. There are multiple options for the display of the stereoscopic image. The use of head mounted displays is one likely implementation. However, the use of 3D projection technologies is another potential technology under consideration, The technology can be adapted in a multitude of ways. The computing platform is scalable, such that the number, resolution, and sensitivity of the cameras can be leveraged to improve image resolution and field of view. Miniaturization efforts can be pursued to shrink the package down for better mobility. Power savings studies can be performed to enable unattended, remote sensing packages. Image compression and transmission technologies can be incorporated to enable an improved telepresence experience.

  12. High resolution integral holography using Fourier ptychographic approach.

    PubMed

    Li, Zhaohui; Zhang, Jianqi; Wang, Xiaorui; Liu, Delian

    2014-12-29

    An innovative approach is proposed for calculating high resolution computer generated integral holograms by using the Fourier Ptychographic (FP) algorithm. The approach initializes a high resolution complex hologram with a random guess, and then stitches together low resolution multi-view images, synthesized from the elemental images captured by integral imaging (II), to recover the high resolution hologram through an iterative retrieval with FP constrains. This paper begins with an analysis of the principle of hologram synthesis from multi-projections, followed by an accurate determination of the constrains required in the Fourier ptychographic integral-holography (FPIH). Next, the procedure of the approach is described in detail. Finally, optical reconstructions are performed and the results are demonstrated. Theoretical analysis and experiments show that our proposed approach can reconstruct 3D scenes with high resolution.

  13. Update on High-Resolution Geodetically Controlled LROC Polar Mosaics

    NASA Astrophysics Data System (ADS)

    Archinal, B.; Lee, E.; Weller, L.; Richie, J.; Edmundson, K.; Laura, J.; Robinson, M.; Speyerer, E.; Boyd, A.; Bowman-Cisneros, E.; Wagner, R.; Nefian, A.

    2015-10-01

    We describe progress on high-resolution (1 m/pixel) geodetically controlled LROC mosaics of the lunar poles, which can be used for locating illumination resources (for solar power or cold traps) or landing site and surface operations planning.

  14. High Resolution CryoFESEM of Microbial Surfaces

    NASA Astrophysics Data System (ADS)

    Erlandsen, Stanley; Lei, Ming; Martin-Lacave, Ines; Dunny, Gary; Wells, Carol

    2003-08-01

    The outer surfaces of three microorganisms, Giardia lamblia, Enterococcus faecalis, and Proteus mirabilis, were investigated by cryo-immobilization followed by sublimation of extracellular ice and cryocoating with either Pt alone or Pt plus carbon. Cryocoated samples were examined at [minus sign]125°C in either an in-lens field emission SEM or a below-the-lens field emission SEM. Cryocoating with Pt alone was sufficient for low magnification observation, but attempts to do high-resolution imaging resulted in radiolysis and cracking of the specimen surface. Double coating with Pt and carbon, in combination with high resolution backscatter electron detectors, enabled high-resolution imaging of the glycocalyx of bacteria, revealing a sponge-like network over the surface. High resolution examination of bacterial flagella also revealed a periodic substructure. Common artifacts included radiolysis leading to “cracking” of the surface, and insufficient deposition of Pt resulting in the absence of detectable surface topography.

  15. High resolution difference schemes for compressible gas dynamics

    SciTech Connect

    Woodward, P.; Colella, P.

    1980-07-30

    The advantages and disadvantages of four new high-resolution difference schemes, namely the von Neumann-Richtmyer, Godunovs, MUSCL and Glimms, for mathematically representing physical conditions in compressible gas flows are compared. (LCL)

  16. Methodology of high-resolution photography for mural condition database

    NASA Astrophysics Data System (ADS)

    Higuchi, R.; Suzuki, T.; Shibata, M.; Taniguchi, Y.

    2015-08-01

    Digital documentation is one of the most useful techniques to record the condition of cultural heritage. Recently, high-resolution images become increasingly useful because it is possible to show general views of mural paintings and also detailed mural conditions in a single image. As mural paintings are damaged by environmental stresses, it is necessary to record the details of painting condition on high-resolution base maps. Unfortunately, the cost of high-resolution photography and the difficulty of operating its instruments and software have commonly been an impediment for researchers and conservators. However, the recent development of graphic software makes its operation simpler and less expensive. In this paper, we suggest a new approach to make digital heritage inventories without special instruments, based on our recent our research project in Üzümlü church in Cappadocia, Turkey. This method enables us to achieve a high-resolution image database with low costs, short time, and limited human resources.

  17. AVHRR/1-FM Advanced Very High Resolution Radiometer

    NASA Technical Reports Server (NTRS)

    1979-01-01

    The advanced very high resolution radiometer is discussed. The program covers design, construction, and test of a breadboard model, engineering model, protoflight model, mechanical/structural model, and a life test model. Special bench test and calibration equipment was developed for use on the program. The flight model program objectives were to fabricate, assemble and test four of the advanced very high resolution radiometers along with a bench cooler and collimator.

  18. Volumetric expiratory high-resolution CT of the lung.

    PubMed

    Nishino, Mizuki; Hatabu, Hiroto

    2004-11-01

    We developed a volumetric expiratory high-resolution CT (HRCT) protocol that provides combined inspiratory and expiratory volumetric imaging of the lung without increasing radiation exposure, and conducted a preliminary feasibility assessment of this protocol to evaluate diffuse lung disease with small airway abnormalities. The volumetric expiratory high-resolution CT increased the detectability of the conducting airway to the areas of air trapping (P<0.0001), and added significant information about extent and distribution of air trapping (P<0.0001).

  19. Fabrication of [001]-oriented tungsten tips for high resolution scanning tunneling microscopy

    PubMed Central

    Chaika, A. N.; Orlova, N. N.; Semenov, V. N.; Postnova, E. Yu.; Krasnikov, S. A.; Lazarev, M. G.; Chekmazov, S. V.; Aristov, V. Yu.; Glebovsky, V. G.; Bozhko, S. I.; Shvets, I. V.

    2014-01-01

    The structure of the [001]-oriented single crystalline tungsten probes sharpened in ultra-high vacuum using electron beam heating and ion sputtering has been studied using scanning and transmission electron microscopy. The electron microscopy data prove reproducible fabrication of the single-apex tips with nanoscale pyramids grained by the {011} planes at the apexes. These sharp, [001]-oriented tungsten tips have been successfully utilized in high resolution scanning tunneling microscopy imaging of HOPG(0001), SiC(001) and graphene/SiC(001) surfaces. The electron microscopy characterization performed before and after the high resolution STM experiments provides direct correlation between the tip structure and picoscale spatial resolution achieved in the experiments. PMID:24434734

  20. Aberration correction by maximizing generalized sharpness metrics.

    PubMed

    Fienup, J R; Miller, J J

    2003-04-01

    The technique of maximizing sharpness metrics has been used to estimate and compensate for aberrations with adaptive optics, to correct phase errors in synthetic-aperture radar, and to restore images. The largest class of sharpness metrics is the sum over a nonlinear point transformation of the image intensity. How the second derivative of the point nonlinearity varies with image intensity determines the effects of various metrics on the imagery. Some metrics emphasize making shadows darker, and other emphasize making bright points brighter. One can determine the image content needed to pick the best metric by computing the statistics of the image autocorrelation or of the Fourier magnitude, either of which is independent of the phase error. Computationally efficient, closed-form expressions for the gradient make possible efficient search algorithms to maximize sharpness.

  1. Zonal spherical aberration correction utilizing axial electrodes

    NASA Astrophysics Data System (ADS)

    Chao, Liang C.

    2005-01-01

    Spherical aberration is important in focused ion beam applications where large aperture angles are needed to obtain high beam currents because it results in large tails on the current density distribution. Merwe has shown that for coaxial lenses, negative spherical aberration can be found for rays pass through zonal regions. Merwe"s calculation is valid only for periodic or quasi-periodic lenses and requires a constant axial potential distribution. We have calculated zonal focusing properties of lenses with axial electrodes using nine-point finite difference method and direct ray tracing. Our calculation results indicate that an axial electrode protruding partially into the lens can correct the spherical aberration. When a three-element electrostatic lens is operated at deceleration mode, the introduction of an axial electrode creates zonal regions where the spherical aberration is negative. At deceleration mode, the induced surface charges on the axial electrode have an opposite sign relative to the primary beam. This is in agreement with our previous findings on the study of the correction of spherical aberration utilizing space charges. Same phenomenon was found when an axial electrode is used in conjunction with a cathode lens.

  2. Designing Aberration-Corrected Solid Unstable Resonators

    NASA Technical Reports Server (NTRS)

    Lang, Robert J.

    1994-01-01

    In improved method of designing solid unstable resonator of laser diode, shapes of mirrors calculated to yield specified mode. Ray tracing used to compute shape of initially unspecified end mirror, given shape of initially specified end mirror and specified output mode. No need to accept aberrations or suboptimal circular shapes, to make iterative design computations in effort to converge on desired mode, or to assume paraxiality of rays: Angles between rays and optical axis large, cross sections of surfaces noncircular, and computed shape of end mirror exact. End mirror corrects for all aberrations.

  3. Variable zoom system with aberration correction capability

    NASA Astrophysics Data System (ADS)

    Lu, Yang; Stockbridge, Christopher R.; Hoffman, Samuel M.; Bifano, Thomas G.

    2012-07-01

    We describe experiments conducted with two deformable mirrors (DMs) at fixed locations in an optical microscope imaging system. In this configuration, the DM shapes are controlled to provide 2.5× zoom capability, to allow dynamic focus control and to compensate for aberrations of the fixed optical components. Zoom is achieved by simultaneously adjusting focal lengths of the two DMs, which are inserted between an infinity-corrected microscope objective and a tube lens. Image quality is measured using contrast modulation, and performance of the system is quantified, demonstrating an improved point spread function in the adaptively compensated system.

  4. Design and implementation of spaceborne high resolution infrared touch screen

    NASA Astrophysics Data System (ADS)

    Li, Tai-guo; Li, Wen-xin; Dong, Yi-peng; Ma, Wen; Xia, Jia-gao

    2015-10-01

    For the consideration of the special application environment of the electronic products used in aerospace and to further more improve the human-computer interaction of the manned aerospace area. The research is based on the design and implementation way of the high resolution spaceborne infrared touch screen on the basis of FPGA and DSP frame structure. Beside the introduction of the whole structure for the high resolution spaceborne infrared touch screen system, this essay also gives the detail information about design of hardware for the high resolution spaceborne infrared touch screen system, FPGA design, GUI design and DSP algorithm design based on Lagrange interpolation. What is more, the easy makes a comprehensive research of the reliability design for the high resolution spaceborne infrared touch screen for the special purpose of it. Besides, the system test is done after installation of spaceborne infrared touch screen. The test result shows that the system is simple and reliable enough, which has a stable running environment and high resolution, which certainly can meet the special requirement of the manned aerospace instrument products.

  5. High-resolution field shaping utilizing a masked multileaf collimator.

    PubMed

    Williams, P C; Cooper, P

    2000-08-01

    Multileaf collimators (MLCs) have become an important tool in the modern radiotherapy department. However, the current limit of resolution (1 cm at isocentre) can be too coarse for acceptable shielding of all fields. A number of mini- and micro-MLCs have been developed, with thinner leaves to achieve approved resolution. Currently however, such devices are limited to modest field sizes and stereotactic applications. This paper proposes a new method of high-resolution beam collimation by use of a tertiary grid collimator situated below the conventional MLC. The width of each slit in the grid is a submultiple of the MLC width. A composite shaped field is thus built up from a series of subfields, with the main MLC defining the length of each strip within each subfield. Presented here are initial findings using a prototype device. The beam uniformity achievable with such a device was examined by measuring transmission profiles through the grid using a diode. Profiles thus measured were then copied and superposed to generate composite beams, from which the uniformity achievable could be assessed. With the average dose across the profile normalized to 100%, hot spots up to 5.0% and troughs of 3% were identified for a composite beam of 2 x 5.0 mm grids, as measured at Dmax for a 6 MV beam. For a beam composed from 4 x 2.5 mm grids, the maximum across the profile was 3.0% above the average, and the minimum 2.5% below. Actual composite profiles were also formed using the integrating properties of film, with the subfield indexing performed using an engineering positioning stage. The beam uniformity for these fields compared well with that achieved in theory using the diode measurements. Finally sine wave patterns were generated to demonstrate the potential improvements in field shaping and conformity using this device as opposed to the conventional MLC alone. The scalloping effect on the field edge commonly seen on MLC fields was appreciably reduced by use of 2 x 5.0 mm

  6. EDITORIAL: High-resolution noncontact atomic force microscopy High-resolution noncontact atomic force microscopy

    NASA Astrophysics Data System (ADS)

    Pérez, Rubén; García, Ricardo; Schwarz, Udo

    2009-06-01

    original papers authored by many of the leading groups in the field with the goal of providing a well-balanced overview on the state-of-the-art in this rapidly evolving field. These papers, many of which are based on notable presentations given during the Madrid conference, feature highlights such as (1) the development of sophisticated force spectroscopy procedures that are able to map the complete 3D tip-sample force field on different surfaces; (2) the considerable resolution improvement of Kelvin probe force microscopy (reaching, in some cases, the atomic scale), which is accompanied by a thorough, quantitative understanding of the contrast observed; (3) the perfecting of atomic resolution imaging on insulating substrates, which helps reshape our microscopic understanding of surface properties and chemical activity of these surfaces; (4) the description of instrumental and methodological developments that pave the way to the atomic-scale characterization of magnetic and electronic properties of nanostructures, and last but not least (5) the extension of dynamic imaging modes to high-resolution operation in liquids, ultimately achieving atomic resolution. The latter developments are already having a significant impact in the highly competitive field of biological imaging under physiological conditions. This special issue of Nanotechnology would not have been possible without the highly professional support from Nina Couzin, Amy Harvey, Alex Wotherspoon and the entire Nanotechnology team at IOP Publishing. We are thankful for their help in pushing this project forward. We also thank the authors who have contributed their excellent original articles to this issue, the referees whose comments have helped make the issue an accurate portrait of this rapidly moving field, and the entire NC-AFM community that continues to drive NC-AFM to new horizons.

  7. High-resolution Urban Image Classification Using Extended Features

    SciTech Connect

    Vatsavai, Raju

    2011-01-01

    High-resolution image classification poses several challenges because the typical object size is much larger than the pixel resolution. Any given pixel (spectral features at that location) by itself is not a good indicator of the object it belongs to without looking at the broader spatial footprint. Therefore most modern machine learning approaches that are based on per-pixel spectral features are not very effective in high- resolution urban image classification. One way to overcome this problem is to extract features that exploit spatial contextual information. In this study, we evaluated several features in- cluding edge density, texture, and morphology. Several machine learning schemes were tested on the features extracted from a very high-resolution remote sensing image and results were presented.

  8. Single sensor processing to obtain high resolution color component signals

    NASA Technical Reports Server (NTRS)

    Glenn, William E. (Inventor)

    2010-01-01

    A method for generating color video signals representative of color images of a scene includes the following steps: focusing light from the scene on an electronic image sensor via a filter having a tri-color filter pattern; producing, from outputs of the sensor, first and second relatively low resolution luminance signals; producing, from outputs of the sensor, a relatively high resolution luminance signal; producing, from a ratio of the relatively high resolution luminance signal to the first relatively low resolution luminance signal, a high band luminance component signal; producing, from outputs of the sensor, relatively low resolution color component signals; and combining each of the relatively low resolution color component signals with the high band luminance component signal to obtain relatively high resolution color component signals.

  9. Modified Noise Power Ratio testing of high resolution digitizers

    SciTech Connect

    McDonald, T.S.

    1994-05-01

    A broadband, full signal range, side-by-side (tandem) test method for estimating the internal noise performance of high resolution digitizers is described and illustrated. The technique involves a re-definition of the traditional Noise Power Ratio (NPR) test, a change that not only makes this test applicable to higher resolution systems than was previously practical, but also enhances its value and flexibility. Since coherence analysis is the basis of this new definition, and since the application of coherence procedures to high resolution data poses several problems, this report discusses these problems and their resolution.

  10. High-resolution seismic studies applied to injected geothermal fluids

    SciTech Connect

    Smith, A.T.; Kasameyer, P.

    1985-01-01

    The application of high-resolution microseismicity studies to the problem of monitoring injected fluids is one component of the Geothermal Injection Monitoring Project at LLNL. The evaluation of microseismicity includes the development of field techniques, and the acquisition and processing of events during the initial development of a geothermal field. To achieve a specific detection threshold and location precision, design criteria are presented for seismic networks. An analysis of a small swarm near Mammoth Lakes, California, demonstrates these relationships and the usefulness of high-resolution seismic studies. A small network is currently monitoring the Mammoth-Pacific geothermal power plant at Casa Diablo as it begins production.

  11. Theoretical Problems in High Resolution Solar Physics, 2

    NASA Technical Reports Server (NTRS)

    Athay, G. (Editor); Spicer, D. S. (Editor)

    1987-01-01

    The Science Working Group for the High Resolution Solar Observatory (HRSO) laid plans beginning in 1984 for a series of workshops designed to stimulate a broadbased input from the scientific community to the HRSO mission. These workshops have the dual objectives of encouraging an early start on the difficult theoretical problems in radiative transfer, magnetohydrodynamics, and plasma physics that will be posed by the HRSO data, and maintaining current discussions of results in high resolution solar studies. This workshop was the second in the series. The workshop format presented invited review papers during the formal sessions and contributed poster papers for discussions during open periods. Both are presented.

  12. High Resolution EUV & FUV Spectroscopy of DA White Dwarfs

    NASA Astrophysics Data System (ADS)

    Barstow, M. A.; Good, S. A.; Bannister, N. P.; Burleigh, M. R.; Holberg, J. B.; Bruhweiler, F. C.; Napiwotzki, R.; Cruddace, R. G.; Kowalski, M. P.

    We report on recent results from a high-resolution spectroscopic survey of hot DA white dwarfs, based on IUE, FUSE and HST observations. For the first time, we address the measurement of element abundances in a completely objective manner with a spectroscopic model fitting technique, which allows us to consider formally the limits that can be placed on abundances in stars where no heavy elements are detected. We also include our latest analysis of the high resolution EUV spectrum of G191-B2B recorded by J-PEX.

  13. Wide swath and high resolution optical imaging satellite of Japan

    NASA Astrophysics Data System (ADS)

    Katayama, Haruyoshi; Kato, Eri; Imai, Hiroko; Sagisaka, Masakazu

    2016-05-01

    The "Advanced optical satellite" (tentative name) is a follow-on mission from ALOS. Mission objectives of the advanced optical satellite is to build upon the existing advanced techniques for global land observation using optical sensors, as well as to promote data utilization for social needs. Wide swath and high resolution optical imager onboard the advanced optical satellite will extend the capabilities of earlier ALOS missions. The optical imager will be able to collect high-resolution (< 1 m) and wide-swath (70 km) images with high geo-location accuracy. This paper introduces a conceptual design of the advanced optical satellite.

  14. Microbeam X-Ray Standing Wave and High Resolution Diffraction

    SciTech Connect

    Kazimirov, A.; Bilderback, D.H.; Huang, R.; Sirenko, A.

    2004-05-12

    Post-focusing collimating optics are introduced as a tool to condition X-ray microbeams for the use in high-resolution X-ray diffraction and scattering techniques. As an example, a one-bounce imaging capillary and miniature Si(004) channel-cut crystal were used to produce a microbeam with 10 {mu}m size and an ultimate angular resolution of 2.5 arc sec. This beam was used to measure the strain in semiconductor microstructures by using X-ray high resolution diffraction and standing wave techniques to {delta}d/d < 5x10-4.

  15. On the application and extension of Harten's high resolution scheme

    NASA Technical Reports Server (NTRS)

    Yee, H. C.; Warming, R. F.; Harten, A.

    1982-01-01

    Extensions of a second order high resolution explicit method for the numerical computation of weak solutions of one dimensonal hyperbolic conservation laws are discussed. The main objectives were (1) to examine the shock resoluton of Harten's method for a two dimensional shock reflection problem, (2) to study the use of a high resolution scheme as a post-processor to an approximate steady state solution, and (3) to construct an implicit in the delta-form using Harten's scheme for the explicit operator and a simplified iteration matrix for the implicit operator.

  16. High resolution BPMS with integrated gain correction system

    SciTech Connect

    Wendt, M.; Briegel, C.; Eddy, N.; Fellenz, B.; Gianfelice, E.; Prieto, P.; Rechenmacher, R.; Voy, D.; Terunuma, N.; Urakawa, J.; /KEK, Tsukuba

    2009-08-01

    High resolution beam position monitors (BPM) are an essential tool to achieve and reproduce a low vertical beam emittance at the KEK Accelerator Test Facility (ATF) damping ring. The ATF damping ring (DR) BPMs are currently upgraded with new high resolution read-out electronics. Based on analog and digital down-conversion techniques, the upgrade includes an automatic gain calibration system to correct for slow drift effects and ensure high reproducible beam position readings. The concept and its technical realization, as well as preliminary results of beam studies are presented.

  17. High resolution, high frame rate video technology development plan and the near-term system conceptual design

    NASA Technical Reports Server (NTRS)

    Ziemke, Robert A.

    1990-01-01

    The objective of the High Resolution, High Frame Rate Video Technology (HHVT) development effort is to provide technology advancements to remove constraints on the amount of high speed, detailed optical data recorded and transmitted for microgravity science and application experiments. These advancements will enable the development of video systems capable of high resolution, high frame rate video data recording, processing, and transmission. Techniques such as multichannel image scan, video parameter tradeoff, and the use of dual recording media were identified as methods of making the most efficient use of the near-term technology.

  18. Displacement Talbot lithography: a new method for high-resolution patterning of large areas.

    PubMed

    Solak, Harun H; Dais, Christian; Clube, Francis

    2011-05-23

    Periodic micro and nano-structures can be lithographically produced using the Talbot effect. However, the limited depth-of-field of the self-images has effectively prevented its practical use, especially for high-resolution structures with periods less than 1 micrometer. In this article we show that by integrating the diffraction field transmitted by a grating mask over a distance of one Talbot period, one can obtain an effective image that is independent of the absolute distance from the mask. In this way high resolution periodic patterns can be printed without the depth-of-field limitation of Talbot self-images. For one-dimensional patterns the image obtained is shown to be related to the convolution of the mask transmission function with itself. This technique, which we call Displacement Talbot Lithography (DTL), enables high-resolution photolithography without the need for complex and expensive projection optics for the production of periodic structures like diffraction gratings or photonic crystals. Experimental results showing the printing of linear gratings and an array of holes on a hexagonal lattice are presented.

  19. High-resolution polar climate parameters derived from 1-km AVHRR data

    SciTech Connect

    Hutchinson, T.A.; Scambos, T.A.

    1997-11-01

    This paper describes the development of a time-series of composites of albedo, surface temperature, and sea ice motion. The composites will be generated from high-resolution (Local Area Coverage and High Resolution Picture Transmission) Advanced Very High Resolution Radiometer (AVHRR). Composites of albedo and surface (skin) temperature will be derived from AVHRR data within three hours of two selected local times (0400 and 1400 for the northern hemisphere, and 0200 and 1600 for the southern hemisphere) for each day. These products will be gridded at 1.25 km cell size in an equal-area projection compatible with recent gridded products from Special Sensor Microwave/Imager data and planned products from the TIROS Operational Verticle Sounder and other AVHRR data sets. Sea ice motion will be calculated once per day by comparing clear-sky image data of sea ice over a three-day period, and reported on a 1.25 km grid. A brief discussion of a reconnaissance survey of the output geophysical parameters for the Northern Hemisphere between August and October 1993 is also presented. 9 refs., 5 figs., 2 tabs.

  20. High resolution frequency to time domain transformations applied to the stepped carrier MRIS measurements

    NASA Technical Reports Server (NTRS)

    Ardalan, Sasan H.

    1992-01-01

    Two narrow-band radar systems are developed for high resolution target range estimation in inhomogeneous media. They are reformulations of two presently existing systems such that high resolution target range estimates may be achieved despite the use of narrow bandwidth radar pulses. A double sideband suppressed carrier radar technique originally derived in 1962, and later abandoned due to its inability to accurately measure target range in the presence of an interfering reflection, is rederived to incorporate the presence of an interfering reflection. The new derivation shows that the interfering reflection causes a period perturbation in the measured phase response. A high resolution spectral estimation technique is used to extract the period of this perturbation leading to accurate target range estimates independent of the signal-to-interference ratio. A non-linear optimal signal processing algorithm is derived for a frequency-stepped continuous wave radar system. The resolution enhancement offered by optimal signal processing of the data over the conventional Fourier Transform technique is clearly demonstrated using measured radar data. A method for modeling plane wave propagation in inhomogeneous media based on transmission line theory is derived and studied. Several simulation results including measurement of non-uniform electron plasma densities that develop near the heat tiles of a space re-entry vehicle are presented which verify the validity of the model.

  1. The Potential for Bayesian Compressive Sensing to Significantly Reduce Electron Dose in High Resolution STEM Images

    SciTech Connect

    Stevens, Andrew J.; Yang, Hao; Carin, Lawrence; Arslan, Ilke; Browning, Nigel D.

    2014-02-11

    The use of high resolution imaging methods in the scanning transmission electron microscope (STEM) is limited in many cases by the sensitivity of the sample to the beam and the onset of electron beam damage (for example in the study of organic systems, in tomography and during in-situ experiments). To demonstrate that alternative strategies for image acquisition can help alleviate this beam damage issue, here we apply compressive sensing via Bayesian dictionary learning to high resolution STEM images. These experiments successively reduce the number of pixels in the image (thereby reducing the overall dose while maintaining the high resolution information) and show promising results for reconstructing images from this reduced set of randomly collected measurements. We show that this approach is valid for both atomic resolution images and nanometer resolution studies, such as those that might be used in tomography datasets, by applying the method to images of strontium titanate and zeolites. As STEM images are acquired pixel by pixel while the beam is scanned over the surface of the sample, these post acquisition manipulations of the images can, in principle, be directly implemented as a low-dose acquisition method with no change in the electron optics or alignment of the microscope itself.

  2. Human enamel structure studied by high resolution electron microscopy

    SciTech Connect

    Wen, S.L. )

    1989-01-01

    Human enamel structural features are characterized by high resolution electron microscopy. The human enamel consists of polycrystals with a structure similar to Ca10(PO4)6(OH)2. This article describes the structural features of human enamel crystal at atomic and nanometer level. Besides the structural description, a great number of high resolution images are included. Research into the carious process in human enamel is very important for human beings. This article firstly describes the initiation of caries in enamel crystal at atomic and unit-cell level and secondly describes the further steps of caries with structural and chemical demineralization. The demineralization in fact, is the origin of caries in human enamel. The remineralization of carious areas in human enamel has drawn more and more attention as its potential application is realized. This process has been revealed by high resolution electron microscopy in detail in this article. On the other hand, the radiation effects on the structure of human enamel are also characterized by high resolution electron microscopy. In order to reveal this phenomenon clearly, a great number of electron micrographs have been shown, and a physical mechanism is proposed. 26 references.

  3. Reproducible high-resolution multispectral image acquisition in dermatology

    NASA Astrophysics Data System (ADS)

    Duliu, Alexandru; Gardiazabal, José; Lasser, Tobias; Navab, Nassir

    2015-07-01

    Multispectral image acquisitions are increasingly popular in dermatology, due to their improved spectral resolution which enables better tissue discrimination. Most applications however focus on restricted regions of interest, imaging only small lesions. In this work we present and discuss an imaging framework for high-resolution multispectral imaging on large regions of interest.

  4. High-resolution imaging of upper limb neuropathies.

    PubMed

    Howe, Benjamin Matthew; Spinner, Robert J; Felmlee, Joel P; Amrami, Kimberly K

    2015-04-01

    MRI of the peripheral nerves continues to grow technologically and in clinical use. This article reviews the technological aspects and basic interpretation of high-resolution MR imaging of the upper extremity nerves. These techniques work with 1.5-, or preferably 3-T, scanners regardless of vendors. The article also includes selected pitfalls in the interpretation of upper extremity nerve MRI.

  5. Persistence Diagrams of High-Resolution Temporal Rainfall

    NASA Astrophysics Data System (ADS)

    Fernández Méndez, F.; Carsteanu, A. A.

    2015-12-01

    This study applies Topological Data Analysis (TDA), by generating persistence diagrams to uncover patterns in the data of high-resolution temporal rainfall intensities from Iowa City (IIHR, U of Iowa). Persistence diagrams are a way to identify essential cycles in state-space representations of the data.

  6. Application of Classification Models to Pharyngeal High-Resolution Manometry

    ERIC Educational Resources Information Center

    Mielens, Jason D.; Hoffman, Matthew R.; Ciucci, Michelle R.; McCulloch, Timothy M.; Jiang, Jack J.

    2012-01-01

    Purpose: The authors present 3 methods of performing pattern recognition on spatiotemporal plots produced by pharyngeal high-resolution manometry (HRM). Method: Classification models, including the artificial neural networks (ANNs) multilayer perceptron (MLP) and learning vector quantization (LVQ), as well as support vector machines (SVM), were…

  7. High-Resolution Land Use and Land Cover Mapping

    USGS Publications Warehouse

    ,

    1999-01-01

    As the Nation?s population grows, quantifying, monitoring, and managing land use becomes increasingly important. The U.S. Geological Survey (USGS) has a long heritage of leadership and innovation in land use and land cover (LULC) mapping that has been the model both nationally and internationally for over 20 years. At present, the USGS is producing high-resolution LULC data for several watershed and urban areas within the United States. This high-resolution LULC mapping is part of an ongoing USGS Land Cover Characterization Program (LCCP). The four components of the LCCP are global (1:2,000,000-scale), national (1:100,000-scale), urban (1:24,000-scale), and special projects (various scales and time periods). Within the urban and special project components, the USGS Rocky Mountain Mapping Center (RMMC) is collecting historical as well as contemporary high-resolution LULC data. RMMC?s high-resolution LULC mapping builds on the heritage and success of previous USGS LULC programs and provides LULC information to meet user requirements.

  8. High-Resolution Nuclear Magnetic Resonance of Solids.

    ERIC Educational Resources Information Center

    Maciel, Gary E.

    1984-01-01

    Examines recent developments in techniques for obtaining high-resolution nuclear magnetic resonance (NMR) spectra on solid samples, discussing the kinds of applications for which these techniques are well suited. Also discusses the characteristics of NMR of solids and generating magnetization for NMR in solids. (JN)

  9. High resolution bone mineral densitometry with a gamma camera

    NASA Technical Reports Server (NTRS)

    Leblanc, A.; Evans, H.; Jhingran, S.; Johnson, P.

    1983-01-01

    A technique by which the regional distribution of bone mineral can be determined in bone samples from small animals is described. The technique employs an Anger camera interfaced to a medical computer. High resolution imaging is possible by producing magnified images of the bone samples. Regional densitometry of femurs from oophorectomised and bone mineral loss.

  10. Workshop on high-resolution, large-acceptance spectrometers

    SciTech Connect

    Zeidman, B.

    1981-01-01

    The purpose of the Workshop on High-Resolution, Large-Acceptance Spectrometers was to provide a means for exchange of information among those actively engaged in the design and construction of these new spectrometers. Thirty-seven papers were prepared for the data base.

  11. High-resolution TFT-LCD for spatial light modulator

    NASA Astrophysics Data System (ADS)

    Lee, JaeWon; Kim, Yong-Hae; Byun, Chun-Won; Pi, Jae-Eun; Oh, Himchan; Kim, GiHeon; Lee, Myung-Lae; Chu, Hye-Yong; Hwang, Chi-Sun

    2014-06-01

    SLM with very fine pixel pitch is needed for the holographic display system. Among various kinds of SLMs, commercially available high resolution LCoS has been widely used as a spatial light modulator. But the size of commercially available LCoS SLM is limited because the manufacturing technology of LCoS is based on the semiconductor process developed on small size Si wafer. Recently very high resolution flat panel display panel (~500ppi) was developed as a "retina display". Until now, the pixel pitch of flat panel display is several times larger than the pixel pitch of LCoS. But considering the possibility of shrink down the pixel pitch with advanced lithographic tools, the application of flat panel display will make it possible to build a SLM with high spatial bandwidth product. We simulated High resolution TFT-LCD panel on glass substrate using oxide semiconductor TFT with pixel pitch of 20um. And we considered phase modulation behavior of LC(ECB) mode. The TFT-LCD panel is reflective type with 4-metal structure with organic planarization layers. The technical challenge for high resolution large area SLM will be discussed with very fine pixel.

  12. Plant respirometer enables high resolution of oxygen consumption rates

    NASA Technical Reports Server (NTRS)

    Foster, D. L.

    1966-01-01

    Plant respirometer permits high resolution of relatively small changes in the rate of oxygen consumed by plant organisms undergoing oxidative metabolism in a nonphotosynthetic state. The two stage supply and monitoring system operates by a differential pressure transducer and provides a calibrated output by digital or analog signals.

  13. A DVD Spectroscope: A Simple, High-Resolution Classroom Spectroscope

    ERIC Educational Resources Information Center

    Wakabayashi, Fumitaka; Hamada, Kiyohito

    2006-01-01

    Digital versatile disks (DVDs) have successfully made up an inexpensive but high-resolution spectroscope suitable for classroom experiments that can easily be made with common material and gives clear and fine spectra of various light sources and colored material. The observed spectra can be photographed with a digital camera, and such images can…

  14. High Resolution Digital Imaging of Paintings: The Vasari Project.

    ERIC Educational Resources Information Center

    Martinez, Kirk

    1991-01-01

    Describes VASARI (the Visual Art System for Archiving and Retrieval of Images), a project funded by the European Community to show the feasibility of high resolution colormetric imaging directly from paintings. The hardware and software used in the system are explained, storage on optical disks is described, and initial results are reported. (five…

  15. HIGH RESOLUTION RESISTIVITY LEAK DETECTION DATA PROCESSING & EVALUATION MEHTODS & REQUIREMENTS

    SciTech Connect

    SCHOFIELD JS

    2007-10-04

    This document has two purposes: {sm_bullet} Describe how data generated by High Resolution REsistivity (HRR) leak detection (LD) systems deployed during single-shell tank (SST) waste retrieval operations are processed and evaluated. {sm_bullet} Provide the basic review requirements for HRR data when Hrr is deployed as a leak detection method during SST waste retrievals.

  16. Large-field high-resolution mosaic movies

    NASA Astrophysics Data System (ADS)

    Hammerschlag, Robert H.; Sliepen, Guus; Bettonvil, Felix C. M.; Jägers, Aswin P. L.; Sütterlin, Peter; Lin, Yong; Martin, Sara F.; Panasenco, Olga; Romashets, Eugene P.

    2013-08-01

    Movies with fields-of-view larger than normal, for high-resolution telescopes, will give a better understanding of processes on the Sun such as filament and active region developments and their possible interactions. New active regions can serve as an igniter of the eruption of a nearby filament. A method to create a large field-of-view is to join several fields-of-view into a mosaic. Fields are imaged quickly, one after another, using fast telescope-pointing. Such a pointing cycle has been automated at the Dutch open telescope (DOT), a high-resolution solar telescope located on the Canary Island La Palma. The number and positions of the subfields are calculated automatically and represented by an array of bright points in the guider image which indicates the subfield centers inside the drawn rectangle of the total field on the computer screen with the whole-sun image. Automatic production of flats is also programmed. For the first time, mosaic movies were programmed from stored information on automated telescope motions. The mosaic movies show larger regions of the solar disk in high resolution and fill a gap between available whole-sun images with limited spatial resolution of synoptic telescopes including space instruments and small-field high-cadence movies of high-resolution solar telescopes.

  17. Evacuee Compliance Behavior Analysis using High Resolution Demographic Information

    SciTech Connect

    Lu, Wei; Han, Lee; Liu, Cheng; Tuttle, Mark A; Bhaduri, Budhendra L

    2014-01-01

    The purpose of this study is to examine whether evacuee compliance behavior with route assignments from different resolutions of demographic data would impact the evacuation performance. Most existing evacuation strategies assume that travelers will follow evacuation instructions, while in reality a certain percent of evacuees do not comply with prescribed instructions. In this paper, a comparison study of evacuation assignment based on Traffic Analysis Zones (TAZ) and high resolution LandScan USA Population Cells (LPC) were conducted for the detailed road network representing Alexandria, Virginia. A revised platform for evacuation modeling built on high resolution demographic data and activity-based microscopic traffic simulation is proposed. The results indicate that evacuee compliance behavior affects evacuation efficiency with traditional TAZ assignment, but it does not significantly compromise the efficiency with high resolution LPC assignment. The TAZ assignment also underestimates the real travel time during evacuation, especially for high compliance simulations. This suggests that conventional evacuation studies based on TAZ assignment might not be effective at providing efficient guidance to evacuees. From the high resolution data perspective, traveler compliance behavior is an important factor but it does not impact the system performance significantly. The highlight of evacuee compliance behavior analysis should be emphasized on individual evacuee level route/shelter assignments, rather than the whole system performance.

  18. High resolution data base for use with MAP

    SciTech Connect

    Tapley, W.C.; Harris, D.B.

    1987-05-05

    A high resolution cartographic data base of thw World is available from the CIA. We obtained this data, extracted portions of the data, and produced cartographic files of varying resolutions. The resulting data files are of the proper format for use with MAP (2), our in-house cartographic plotting program.

  19. High-resolution axial MR imaging of tibial stress injuries

    PubMed Central

    2012-01-01

    Purpose To evaluate the relative involvement of tibial stress injuries using high-resolution axial MR imaging and the correlation with MR and radiographic images. Methods A total of 33 patients with exercise-induced tibial pain were evaluated. All patients underwent radiograph and high-resolution axial MR imaging. Radiographs were taken at initial presentation and 4 weeks later. High-resolution MR axial images were obtained using a microscopy surface coil with 60 × 60 mm field of view on a 1.5T MR unit. All images were evaluated for abnormal signals of the periosteum, cortex and bone marrow. Results Nineteen patients showed no periosteal reaction at initial and follow-up radiographs. MR imaging showed abnormal signals in the periosteal tissue and partially abnormal signals in the bone marrow. In 7 patients, periosteal reaction was not seen at initial radiograph, but was detected at follow-up radiograph. MR imaging showed abnormal signals in the periosteal tissue and entire bone marrow. Abnormal signals in the cortex were found in 6 patients. The remaining 7 showed periosteal reactions at initial radiograph. MR imaging showed abnormal signals in the periosteal tissue in 6 patients. Abnormal signals were seen in the partial and entire bone marrow in 4 and 3 patients, respectively. Conclusions Bone marrow abnormalities in high-resolution axial MR imaging were related to periosteal reactions at follow-up radiograph. Bone marrow abnormalities might predict later periosteal reactions, suggesting shin splints or stress fractures. High-resolution axial MR imaging is useful in early discrimination of tibial stress injuries. PMID:22574840

  20. High-Resolution Molecular Typing of Trypanosoma cruzi in 2 Large Outbreaks of Acute Chagas Disease in Colombia.

    PubMed

    Hernández, Carolina; Vera, Mauricio Javier; Cucunubá, Zulma; Flórez, Carolina; Cantillo, Omar; Buitrago, Luz Stella; González, Marina Stella; Ardila, Susanne; Dueñas, Liliana Zuleta; Tovar, Rubén; Forero, Luis Fernando; Ramírez, Juan David

    2016-10-15

    Oral transmission of Trypanosoma cruzi has gained relevance because of its association with high morbidity and lethality rates. This transmission route is responsible for maintaining the infection of the parasite in sylvatic cycles, and human cases have been associated mainly with the consumption of food contaminated with triatomine feces or didelphid secretions. Several ecological changes allow the intrusion of sylvatic reservoirs and triatomines to the domestic environments with subsequent food contamination. Here, high-resolution molecular tools were used to detect and genotype T. cruzi across humans, reservoirs, and insect vectors in 2 acute outbreaks of presumptive oral transmission in eastern Colombia.

  1. High-Resolution Molecular Typing of Trypanosoma cruzi in 2 Large Outbreaks of Acute Chagas Disease in Colombia.

    PubMed

    Hernández, Carolina; Vera, Mauricio Javier; Cucunubá, Zulma; Flórez, Carolina; Cantillo, Omar; Buitrago, Luz Stella; González, Marina Stella; Ardila, Susanne; Dueñas, Liliana Zuleta; Tovar, Rubén; Forero, Luis Fernando; Ramírez, Juan David

    2016-10-15

    Oral transmission of Trypanosoma cruzi has gained relevance because of its association with high morbidity and lethality rates. This transmission route is responsible for maintaining the infection of the parasite in sylvatic cycles, and human cases have been associated mainly with the consumption of food contaminated with triatomine feces or didelphid secretions. Several ecological changes allow the intrusion of sylvatic reservoirs and triatomines to the domestic environments with subsequent food contamination. Here, high-resolution molecular tools were used to detect and genotype T. cruzi across humans, reservoirs, and insect vectors in 2 acute outbreaks of presumptive oral transmission in eastern Colombia. PMID:27511897

  2. High-resolution climate simulation of the last glacial maximum

    SciTech Connect

    Erickson III, David J

    2008-01-01

    The climate of the last glacial maximum (LGM) is simulated with a high-resolution atmospheric general circulation model, the NCAR CCM3 at spectral truncation of T170, corresponding to a grid cell size of roughly 75 km. The purpose of the study is to assess whether there are significant benefits from the higher resolution simulation compared to the lower resolution simulation associated with the role of topography. The LGM simulations were forced with modified CLIMAP sea ice distribution and sea surface temperatures (SST) reduced by 1 C, ice sheet topography, reduced CO{sub 2}, and 21,000 BP orbital parameters. The high-resolution model captures modern climate reasonably well, in particular the distribution of heavy precipitation in the tropical Pacific. For the ice age case, surface temperature simulated by the high-resolution model agrees better with those of proxy estimates than does the low-resolution model. Despite the fact that tropical SSTs were only 2.1 C less than the control run, there are many lowland tropical land areas 4-6 C colder than present. Comparison of T170 model results with the best constrained proxy temperature estimates (noble gas concentrations in groundwater) now yield no significant differences between model and observations. There are also significant upland temperature changes in the best resolved tropical mountain belt (the Andes). We provisionally attribute this result in part as resulting from decreased lateral mixing between ocean and land in a model with more model grid cells. A longstanding model-data discrepancy therefore appears to be resolved without invoking any unusual model physics. The response of the Asian summer monsoon can also be more clearly linked to local geography in the high-resolution model than in the low-resolution model; this distinction should enable more confident validation of climate proxy data with the high-resolution model. Elsewhere, an inferred salinity increase in the subtropical North Atlantic may have

  3. High-resolution DEM Effects on Geophysical Flow Models

    NASA Astrophysics Data System (ADS)

    Williams, M. R.; Bursik, M. I.; Stefanescu, R. E. R.; Patra, A. K.

    2014-12-01

    Geophysical mass flow models are numerical models that approximate pyroclastic flow events and can be used to assess the volcanic hazards certain areas may face. One such model, TITAN2D, approximates granular-flow physics based on a depth-averaged analytical model using inputs of basal and internal friction, material volume at a coordinate point, and a GIS in the form of a digital elevation model (DEM). The volume of modeled material propagates over the DEM in a way that is governed by the slope and curvature of the DEM surface and the basal and internal friction angles. Results from TITAN2D are highly dependent upon the inputs to the model. Here we focus on a single input: the DEM, which can vary in resolution. High resolution DEMs are advantageous in that they contain more surface details than lower-resolution models, presumably allowing modeled flows to propagate in a way more true to the real surface. However, very high resolution DEMs can create undesirable artifacts in the slope and curvature that corrupt flow calculations. With high-resolution DEMs becoming more widely available and preferable for use, determining the point at which high resolution data is less advantageous compared to lower resolution data becomes important. We find that in cases of high resolution, integer-valued DEMs, very high-resolution is detrimental to good model outputs when moderate-to-low (<10-15°) slope angles are involved. At these slope angles, multiple adjacent DEM cell elevation values are equal due to the need for the DEM to approximate the low slope with a limited set of integer values for elevation. The first derivative of the elevation surface thus becomes zero. In these cases, flow propagation is inhibited by these spurious zero-slope conditions. Here we present evidence for this "terracing effect" from 1) a mathematically defined simulated elevation model, to demonstrate the terracing effects of integer valued data, and 2) a real-world DEM where terracing must be

  4. High-resolution structure of the native histone octamer

    SciTech Connect

    Wood, Christopher M.; Nicholson, James M.; Lambert, Stanley J.; Chantalat, Laurent; Reynolds, Colin D.; Baldwin, John P.

    2005-06-01

    The high-resolution (1.90 Å) model of the native histone octamer allows structural comparisons to be made with the nucleosome-core particle, along with an identification of a likely core-histone binding site. Crystals of native histone octamers (H2A–H2B)–(H4–H3)–(H3′–H4′)–(H2B′–H2A′) from chick erythrocytes in 2 M KCl, 1.35 M potassium phosphate pH 6.9 diffract X-rays to 1.90 Å resolution, yielding a structure with an R{sub work} value of 18.7% and an R{sub free} of 22.2%. The crystal space group is P6{sub 5}, the asymmetric unit of which contains one complete octamer. This high-resolution model of the histone-core octamer allows further insight into intermolecular interactions, including water molecules, that dock the histone dimers to the tetramer in the nucleosome-core particle and have relevance to nucleosome remodelling. The three key areas analysed are the H2A′–H3–H4 molecular cluster (also H2A–H3′–H4′), the H4–H2B′ interaction (also H4′–H2B) and the H2A′–H4 β-sheet interaction (also H2A–H4′). The latter of these three regions is important to nucleosome remodelling by RNA polymerase II, as it is shown to be a likely core-histone binding site, and its disruption creates an instability in the nucleosome-core particle. A majority of the water molecules in the high-resolution octamer have positions that correlate to similar positions in the high-resolution nucleosome-core particle structure, suggesting that the high-resolution octamer model can be used for comparative studies with the high-resolution nucleosome-core particle.

  5. A high resolution (1 km) groundwater model for Indonesia

    NASA Astrophysics Data System (ADS)

    Sutanudjaja, Edwin; Verkaik, Jarno; de Graaf, Inge; van Beek, Rens; Erkens, Gilles; Bierkens, Marc

    2015-04-01

    results. Also we discuss fundamental challenges in high resolution groundwater modeling and address various issues that range from computational challenges - e.g. computational time, memory, and parallelization issues - to lack of sufficient detail/fine information for model validation and parameterization - including atmospheric forcing and emergent scaling problems. References: de Graaf et al., Hydrology & Earth System Sciences (2014), http://dx.doi.org/10.5194/hessd-11-5217-2014 Dürr et al., Global Biogeochemical Cycles (2005), http://dx.doi.org/10.1029/2005GB002515 Gleeson et al., Geophysical Research Letter (2011), http://dx.doi.org/10.1029/2010GL045565 Gleeson et al., Geophysical Research Letter (2014), http://dx.doi.org/10.1002/2014GL059856 Harbaugh et al., MODFLOW-2000 (2000), http://water.usgs.gov/nrp/gwsoftware/modflow2000/ofr00-92.pdf Hartmann & Moosdorf, Geochemistry Geophysics Geosystems (2012), http://dx.doi.org/10.1029/2012GC004370 Sutanudjaja et al., Hydrology & Earth System Sciences (2011), http://dx.doi.org/10.5194/hess-15-2913-2011 Sutanudjaja et al., Water Resources Research (2014a), http://dx.doi.org/10.1002/2013WR013807 Sutanudjaja et al., AGU Fall Meeting (2014b), see: http://globalhydrology.nl/models/pcr-globwb-2-0/ van Beek et al., Water Resources Research (2011), http://dx.doi.org/10.1029/2010WR009791

  6. Space to Think: Large, High-Resolution Displays for Sensemaking

    SciTech Connect

    Andrews, Christopher P.; Endert, Alexander; North, Chris

    2010-05-05

    Space supports human cognitive abilities in a myriad of ways. The note attached to the side of the monitor, the papers spread out on the desk, diagrams scrawled on a whiteboard, and even the keys left out on the counter are all examples of using space to recall, reveal relationships, and think. Technological advances have made it possible to construct large display environments in which space has real meaning. This paper examines how increased space affects the way displays are regarded and used within the context of the cognitively demanding task of sensemaking. A study was conducted observing analysts using a prototype large, high-resolution display to solve an analytic problem. This paper reports on the results of this study and suggests a number of potential design criteria for future sensemaking tools developed for large, high-resolution displays.

  7. High resolution map of light pollution over Poland

    NASA Astrophysics Data System (ADS)

    Netzel, Henryka; Netzel, Paweł

    2016-09-01

    In 1976 Berry introduced a simple mathematical equation to calculate artificial night sky brightness at zenith. In the original model cities, considered as points with given population, are only sources of light emission. In contrary to Berry's model, we assumed that all terrain surface can be a source of light. Emission of light depends on percent of built up area in a given cell. We based on Berry's model. Using field measurements and high-resolution data we obtained the map of night sky brightness over Poland in 100-m resolution. High resolution input data, combined with a very simple model, makes it possible to obtain detailed structures of the night sky brightness without complicating the calculations.

  8. Temperature-dependent high resolution absorption cross sections of propane

    NASA Astrophysics Data System (ADS)

    Beale, Christopher A.; Hargreaves, Robert J.; Bernath, Peter F.

    2016-10-01

    High resolution (0.005 cm-1) absorption cross sections have been measured for pure propane (C3H8). These cross sections cover the 2550-3500 cm-1 region at five temperatures (from 296 to 700 K) and were measured using a Fourier transform spectrometer and a quartz cell heated by a tube furnace. Calibrations were made by comparison to the integrated cross sections of propane from the Pacific Northwest National Laboratory. These are the first high resolution absorption cross sections of propane for the 3 μm region at elevated temperatures. The cross sections provided may be used to monitor propane in combustion environments and in astronomical sources such as the auroral regions of Jupiter, brown dwarfs and exoplanets.

  9. High-resolution imaging of cellular processes in Caenorhabditis elegans.

    PubMed

    Maddox, Amy S; Maddox, Paul S

    2012-01-01

    Differential interference contrast (DIC) imaging of Caenorhabditis elegans embryogenesis led to a Nobel Prize in Physiology or Medicine (Sulston et al., 1983) as did the first use of green fluorescent protein (GFP) in a transgenic C. elegans (Chalfie et al., 1994). Given that C. elegans is free living, does not require exceptional environmental control, and is optically clear, live imaging is a powerful tool in for this model system. Combining genetics with high-resolution imaging has continued to make important contributions to many fields. In this chapter, we discuss how certain aspects of high-resolution microscopy are implemented. This is not an exhaustive review of microscopy; it is meant to be a helpful guide and point of reference for some basic concepts in imaging. While these concepts are largely true for all biological imaging, they are chosen as particularly important for C. elegans. PMID:22226519

  10. Fabricating High-Resolution X-Ray Collimators

    NASA Technical Reports Server (NTRS)

    Appleby, Michael; Atkinson, James E.; Fraser, Iain; Klinger, Jill

    2008-01-01

    A process and method for fabricating multi-grid, high-resolution rotating modulation collimators for arcsecond and sub-arcsecond x-ray and gamma-ray imaging involves photochemical machining and precision stack lamination. The special fixturing and etching techniques that have been developed are used for the fabrication of multiple high-resolution grids on a single array substrate. This technology has application in solar and astrophysics and in a number of medical imaging applications including mammography, computed tomography (CT), single photon emission computed tomography (SPECT), and gamma cameras used in nuclear medicine. This collimator improvement can also be used in non-destructive testing, hydrodynamic weapons testing, and microbeam radiation therapy.

  11. Turbine component casting core with high resolution region

    DOEpatents

    Kamel, Ahmed; Merrill, Gary B.

    2014-08-26

    A hollow turbine engine component with complex internal features can include a first region and a second, high resolution region. The first region can be defined by a first ceramic core piece formed by any conventional process, such as by injection molding or transfer molding. The second region can be defined by a second ceramic core piece formed separately by a method effective to produce high resolution features, such as tomo lithographic molding. The first core piece and the second core piece can be joined by interlocking engagement that once subjected to an intermediate thermal heat treatment process thermally deform to form a three dimensional interlocking joint between the first and second core pieces by allowing thermal creep to irreversibly interlock the first and second core pieces together such that the joint becomes physically locked together providing joint stability through thermal processing.

  12. Progressive display of very high resolution images using wavelets.

    PubMed Central

    Zhang, Ya; Wang, James Z.

    2002-01-01

    Digital or digitized biomedical images often have very high resolutions', which make them difficult or impossible to display on computer screens. Therefore, it is desirable to develop a multiresolution display method with which users can freely browse the contents of those high resolution images. In this paper, we present an improved wavelet-based progressive image display algorithm by stressing on the encoding and decoding process. The encoder, which dynamically determines levels of transform and partition of coefficients, is based on a modified Haar wavelet transform. The decoder retrieves the necessary data and reconstructs the requested region at a scale specified by the user. A prototype system, which enables virtually any size of images to be displayed progressively, has been implemented based on this algorithm. The system has low computational complexity for both encoding and decoding process. Images Figure 2 PMID:12476909

  13. The theory and practice of high resolution scanning electron microscopy

    SciTech Connect

    Joy, D.C. Oak Ridge National Lab., TN )

    1990-01-01

    Recent advances in instrumentation have produced the first commercial examples of what can justifiably be called High Resolution Scanning Electron Microscopes. The key components of such instruments are a cold field emission gun, a small-gap immersion probe-forming lens, and a clean dry-pumped vacuum. The performance of these microscopes is characterized by several major features including a spatial resolution, in secondary electron mode on solid specimens, which can exceed 1nm on a routine basis; an incident probe current density of the order of 10{sup 6} amps/cm{sup 2}; and the ability to maintain these levels of performance over an accelerating voltage range of from 1 to 30keV. This combination of high resolution, high probe current, low contamination and flexible electron-optical conditions provides many new opportunitites for the application of the SEM to materials science, physics, and the life sciences. 27 refs., 14 figs.

  14. High-resolution array processing using implicit eigenvector weighting techniques

    SciTech Connect

    Steele, A.K. ); Byrne, C.L. )

    1990-01-01

    Many high-resolution bearing estimators require the explicit calculation of the eigenvectors and eigenvalues of the cross-spectral matrix of the sensor outputs. Once the eigenvectors have been calculated, various different estimators can be derived by altering the eigenvalues to give a re-weighing of the eigenvectors. For example, in the MUSIC method the eigenvalues corresponding to those eigenvectors in the noise subspace are set to unity, while the eigenvalues corresponding to those eigenvectors in the signal subspace are set to zero. These weighing functions are reminiscent of ideal filter responses in analog filter theory, where practical filters are designed by using polynomial approximations to the ideal desired response. In this paper, the approximation theory developed for filter design is used to derive high-resolution bearing estimators that do not require explicit calculation of the eigenvectors.

  15. High Resolution Scanning Electron Microscopy of Cells Using Dielectrophoresis

    PubMed Central

    Tang, Shi-Yang; Zhang, Wei; Soffe, Rebecca; Nahavandi, Sofia; Shukla, Ravi; Khoshmanesh, Khashayar

    2014-01-01

    Ultrastructural analysis of cells can reveal valuable information about their morphological, physiological, and biochemical characteristics. Scanning electron microscopy (SEM) has been widely used to provide high-resolution images from the surface of biological samples. However, samples need to be dehydrated and coated with conductive materials for SEM imaging. Besides, immobilizing non-adherent cells during processing and analysis is challenging and requires complex fixation protocols. In this work, we developed a novel dielectrophoresis based microfluidic platform for interfacing non-adherent cells with high-resolution SEM at low vacuum mode. The system enables rapid immobilization and dehydration of samples without deposition of chemical residues over the cell surface. Moreover, it enables the on-chip chemical stimulation and fixation of immobilized cells with minimum dislodgement. These advantages were demonstrated for comparing the morphological changes of non-budding and budding yeast cells following Lyticase treatment. PMID:25089528

  16. High-resolution x-ray phase tomography

    NASA Astrophysics Data System (ADS)

    Peele, Andrew G.; Thomas, C. David L.; Clement, John G.; Arhatari, Benedicta D.; Hannah, Kevin M.; Doshi, Chandni; Putkunz, Corey T.; Clark, Jesse N.

    2010-09-01

    X-ray tomography is a workhorse tool of non-destructive imaging. It is used to probe three-dimensional structures across a wide range of length scales for objects that offer good absorption contrast to x-rays. In recent years extremely high resolution imaging (on the order of tens of nanometres) has become possible due to technological advances in x-ray optics. At the same time the requirement for strong absorption contrast has been relaxed thanks to the advent of new experimental and algorithmic techniques in phase imaging. Advances in both resolution and phase imaging can be combined to image biological samples at the sub-cellular level. I will report on recent advances in our work including improvements to the current approaches in extracting phase information at high resolution from measurements of the diffracted intensity from a sample. I will also discuss our current experimental status.

  17. [Development of a high resolution simultaneous microwave plasma torch spectrometer].

    PubMed

    Jiang, Jie; Huan, Yan-Fu; Jin, Wei; Feng, Guo-Dong; Fei, Qiang; Cao, Yan-Bo; Jin, Qin-Han

    2007-11-01

    A unique high resolution simultaneous microwave plasma torch (MPT) atomic emission spectrometer was developed and studied preliminarily. Some advanced technologies were applied to the spectrometer, such as echelle grating, UV-intensified CCD array detector, adjustable microwave generator, and water cooling system for the generator, etc. The detection limits of the spectrometer for some elements were determined, the spectral resolution and pixel resolution of the spectrometer were calculated, and an analysis of a practical sample was carried out. The preliminary results demonstrate that such simultaneous spectrometer has advantages of saving sample and time, possessing high sensitivity and resolution, and low-cost for the purchase and maintenance. Taking analytical figures of merit into consideration, the high resolution simultaneous MPT spectrometer will have extended application areas and greater competition potential as compared with sequential MPT spectrometers.

  18. Note: Differential amplified high-resolution tilt angle measurement system.

    PubMed

    Zhao, Shijie; Li, Yan; Zhang, Enyao; Huang, Pei; Wei, Haoyun

    2014-09-01

    A high-resolution tilt angle measurement system is presented in this paper. In this system, the measurement signal is amplified by two steps: (1) amplified by operational amplifier and (2) differential amplified by two MEMS-based inclinometers. The novel application not only amplifies the signal but, more importantly, substantially reduces the electrical interference and common-mode noise among the same circuit design. Thus, both the extremely high resolution and great long-term stability are achieved in this system. Calibrated by an autocollimator, the system shows a resolution of 2 arc sec. The accuracy is better than ±1.5 arc sec. The zero-drift error is below ±1 arc sec and ±2 arc sec in the short and long term, respectively.

  19. Note: Differential amplified high-resolution tilt angle measurement system

    NASA Astrophysics Data System (ADS)

    Zhao, Shijie; Li, Yan; Zhang, Enyao; Huang, Pei; Wei, Haoyun

    2014-09-01

    A high-resolution tilt angle measurement system is presented in this paper. In this system, the measurement signal is amplified by two steps: (1) amplified by operational amplifier and (2) differential amplified by two MEMS-based inclinometers. The novel application not only amplifies the signal but, more importantly, substantially reduces the electrical interference and common-mode noise among the same circuit design. Thus, both the extremely high resolution and great long-term stability are achieved in this system. Calibrated by an autocollimator, the system shows a resolution of 2 arc sec. The accuracy is better than ±1.5 arc sec. The zero-drift error is below ±1 arc sec and ±2 arc sec in the short and long term, respectively.

  20. Parallelization and Algorithmic Enhancements of High Resolution IRAS Image Construction

    NASA Technical Reports Server (NTRS)

    Cao, Yu; Prince, Thomas A.; Tereby, Susan; Beichman, Charles A.

    1996-01-01

    The Infrared Astronomical Satellite caried out a nearly complete survey of the infrared sky, and the survey data are important for the study of many astrophysical phenomena. However, many data sets at other wavelengths have higher resolutions than that of the co-added IRAS maps, and high resolution IRAS images are strongly desired both for their own information content and their usefulness in correlation. The HIRES program was developed by the Infrared Processing and Analysis Center (IPAC) to produce high resolution (approx. 1') images from IRAS data using the Maximum Correlation Method (MCM). We describe the port of HIRES to the Intel Paragon, a massively parallel supercomputer, other software developments for mass production of HIRES images, and the IRAS Galaxy Atlas, a project to map the Galactic plane at 60 and 100(micro)m.

  1. Airborne laser scanning for high-resolution mapping of Antarctica

    NASA Astrophysics Data System (ADS)

    Csatho, Bea; Schenk, Toni; Krabill, William; Wilson, Terry; Lyons, William; McKenzie, Garry; Hallam, Cheryl; Manizade, Serdar; Paulsen, Timothy

    In order to evaluate the potential of airborne laser scanning for topographic mapping in Antarctica and to establish calibration/validation sites for NASA's Ice, Cloud and land Elevation Satellite (ICESat) altimeter mission, NASA, the U.S. National Science Foundation (NSF), and the U.S. Geological Survey (USGS) joined forces to collect high-resolution airborne laser scanning data.In a two-week campaign during the 2001-2002 austral summer, NASA's Airborne Topographic Mapper (ATM) system was used to collect data over several sites in the McMurdo Sound area of Antarctica (Figure 1a). From the recorded signals, NASA computed laser points and The Ohio State University (OSU) completed the elaborate computation/verification of high-resolution Digital Elevation Models (DEMs) in 2003. This article reports about the DEM generation and some exemplary results from scientists using the geomorphologic information from the DEMs during the 2003-2004 field season.

  2. Protein-DNA binding in high-resolution

    PubMed Central

    Mahony, Shaun; Pugh, B. Franklin

    2015-01-01

    Recent advances in experimental and computational methodologies are enabling ultra-high resolution genome-wide profiles of protein-DNA binding events. For example, the ChIP-exo protocol precisely characterizes protein-DNA crosslinking patterns by combining chromatin immunoprecipitation (ChIP) with 5′ → 3′ exonuclease digestion. Similarly, deeply sequenced chromatin accessibility assays (e.g. DNase-seq and ATACseq) enable the detection of protected footprints at protein-DNA binding sites. With these techniques and others, we have the potential to characterize the individual nucleotides that interact with transcription factors, nucleosomes, RNA polymerases, and other regulatory proteins in a particular cellular context. In this review, we explain the experimental assays and computational analysis methods that enable high-resolution profiling of protein-DNA binding events. We discuss the challenges and opportunities associated with such approaches. PMID:26038153

  3. High resolution reservoir geological modelling using outcrop information

    SciTech Connect

    Zhang Changmin; Lin Kexiang; Liu Huaibo

    1997-08-01

    This is China`s first case study of high resolution reservoir geological modelling using outcrop information. The key of the modelling process is to build a prototype model and using the model as a geological knowledge bank. Outcrop information used in geological modelling including seven aspects: (1) Determining the reservoir framework pattern by sedimentary depositional system and facies analysis; (2) Horizontal correlation based on the lower and higher stand duration of the paleo-lake level; (3) Determining the model`s direction based on the paleocurrent statistics; (4) Estimating the sandbody communication by photomosaic and profiles; (6) Estimating reservoir properties distribution within sandbody by lithofacies analysis; and (7) Building the reservoir model in sandbody scale by architectural element analysis and 3-D sampling. A high resolution reservoir geological model of Youshashan oil field has been built by using this method.

  4. Effective Area of the AXAF High Resolution Camera (HRC)

    NASA Technical Reports Server (NTRS)

    Patnaude, Daniel; Pease, Deron; Donnelly, Hank; Juda, Mike; Jones, Christine; Murray, Steve; Zombeck, Martin; Kraft, Ralph; Kenter, Almus; Meehan, Gary; Meehan, Gary; Swartz, Doug; Elsner, Ron

    1998-01-01

    The AXAF High-Resolution Camera (HRC) was calibrated at NASA MSFC's X-Ray Calibration Facility (XRCF) during 1997 March and April. We have undertaken an analysis of the HRC effective area using all data presently available from the XRCF. We discuss our spectral fitting of the beam-normalization detectors (BNDs), our method of removing higher order contamination lines present in the spectra, and corrections for beam non-uniformities. We apply a model of photon absorption depth in order to fit a smooth curve to the quantum efficiency of the detector. This is then combined with the most recent model of the AXAF High-Resolution Mirror Assembly (HRMA) to determine the ensemble effective area versus energy for the HRC. We also address future goals and concerns.

  5. A Procedure for High Resolution Satellite Imagery Quality Assessment

    PubMed Central

    Crespi, Mattia; De Vendictis, Laura

    2009-01-01

    Data products generated from High Resolution Satellite Imagery (HRSI) are routinely evaluated during the so-called in-orbit test period, in order to verify if their quality fits the desired features and, if necessary, to obtain the image correction parameters to be used at the ground processing center. Nevertheless, it is often useful to have tools to evaluate image quality also at the final user level. Image quality is defined by some parameters, such as the radiometric resolution and its accuracy, represented by the noise level, and the geometric resolution and sharpness, described by the Modulation Transfer Function (MTF). This paper proposes a procedure to evaluate these image quality parameters; the procedure was implemented in a suitable software and tested on high resolution imagery acquired by the QuickBird, WorldView-1 and Cartosat-1 satellites. PMID:22412312

  6. High Resolution Measurements and Electronic Structure Calculations of a Diazanaphthalene

    NASA Astrophysics Data System (ADS)

    Gruet, Sébastien; Goubet, Manuel; Pirali, Olivier

    2014-06-01

    Polycyclic Aromatic Hydrocarbons (PAHs) have long been suspected to be the carriers of so called Unidentified Infrared Bands (UIBs). Most of the results published in the literature report rotationally unresolved spectra of pure carbon as well as heteroatom-containing PAHs species. To date for this class of molecules, the principal source of rotational informations is ruled by microwave (MW) spectroscopy while high resolution measurements reporting rotational structure of the infrared (IR) vibrational bands are very scarce. Recently, some high resolution techniques provided interesting new results to rotationally resolve the IR and far-IR bands of these large carbonated molecules of astrophysical interest. One of them is to use the bright synchrotron radiation as IR continuum source of a high resolution Fourier transform (FTIR) spectrometer. We report the very complementary analysis of the [1,6] naphthyridine (a N-bearing PAH) for which we recorded the microwave spectrum at the PhLAM laboratory (Lille) and the high resolution far-infrared spectrum on the AILES beamline at synchrotron facility SOLEIL. MW spectroscopy provided highly accurate rotational constants in the ground state to perform Ground State Combinations Differences (GSCD) allowing the analysis of the two most intense FT-FIR bands in the 50-900 wn range. Moreover, during this presentation the negative value of the inertial defect in the GS of the molecule will be discussed. A. Leger, J. L. Puget, Astron. Astrophys. 137, L5-L8 (1984) L. J. Allamandola et al. Astrophys. J. 290, L25-L28 (1985). Z. Kisiel et al. J. Mol. Spectrosc. 217, 115 (2003) S. Thorwirth et al. Astrophys. J. 662, 1309 (2007) D. McNaughton et al. J. Chem. Phys. 124, 154305 (2011). S. Albert et al. Faraday Discuss. 150, 71-99 (2011) B. E. Brumfield et al. Phys. Chem. Lett. 3, 1985-1988 (2012) O. Pirali et al. Phys. Chem. Chem. Phys. 15, 10141 (2013).

  7. High-resolution, cryogenic, side-entry type specimen stage

    DOEpatents

    King, Wayne E.; Merkle, Karl L.

    1979-01-01

    A high-resolution, cryogenic side-entry type specimen stage includes a copper block within which a specimen can be positioned in the electron beam of an electron microscope, one end of the copper block constituting a specimen heat exchanger, means for directing a flow of helium at cryogenic temperature into the heat exchanger, and electrical leads running from the specimen to the exterior of the microscope for four point D.C. electrical resistivity measurements.

  8. Achievement of a 920-MHz High Resolution NMR

    NASA Astrophysics Data System (ADS)

    Hashi, Kenjiro; Shimizu, Tadashi; Goto, Atsushi; Kiyoshi, Tsukasa; Matsumoto, Shinji; Wada, Hitoshi; Fujito, Teruaki; Hasegawa, Ken-ichi; Yoshikawa, Masatoshi; Miki, Takashi; Ito, Satoshi; Hamada, Mamoru; Hayashi, Seiji

    2002-06-01

    We have developed a 920-MHz NMR system and performed the proton NMR measurement of H 2O and ethylbenzene using the superconducting magnet operating at 21.6 T (920 MHz for proton), which is the highest field produced by a superconducting NMR magnet in the persistent mode. From the NMR measurements, it is verified that both homogeneity and stability of the magnet have a specification sufficient for a high resolution NMR.

  9. High resolution microwave spectrometer sounder (HIMSS), volume 1, book 2

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The following topics are presented with respect to the high resolution microwave spectrometer sounder (HIMSS) that is to be used as an instrument for NASA's Earth Observing System (EOS): (1) preliminary program plans; (2) contract end item (CEI) specification; and (3) the instrument interface description document. Under the preliminary program plans section, plans dealing with the following subject areas are discussed: spares, performance assurance, configuration management, software implementation, contamination, calibration management, and verification.

  10. High-resolution schemes for hyperbolic conservation laws

    NASA Technical Reports Server (NTRS)

    Harten, A.

    1982-01-01

    A class of new explicit second order accurate finite difference schemes for the computation of weak solutions of hyperbolic conservation laws is presented. These highly nonlinear schemes are obtained by applying a nonoscillatory first order accurae scheme to an appropriately modified flux function. The so derived second order accurate schemes achieve high resolution while preserving the robustness of the original nonoscillatory first order accurate scheme.

  11. LandScan 2013 High Resolution Global Population Data Set

    SciTech Connect

    2014-07-01

    The LandScan data set is a worldwide population database compiled on a 30"x30" latitude/longitude grid. Census counts (at sub-national level) were apportioned to each grid cell based on likelihood coefficients, which are based on land cover, slope, road proximity, high-resolution imagery, and other data sets. The LandScan data set was developed as part of Oak Ridge National Laboratory (ORNL) Global Population Project for estimating ambient populations at risk.

  12. New Challenges in High-Resolution Modeling of Hurricanes

    NASA Astrophysics Data System (ADS)

    Chen, S. S.

    2006-12-01

    The extreme active Atlantic hurricane seasons in recent years have highlighted the urgent need for a better understanding of the factors that contribute to hurricane intensity and for development of the corresponding advanced hurricane prediction models to improve intensity forecasts. The lack of skill in present forecasts of hurricane structure and intensity may be attributed in part to deficiencies in the current prediction models: insufficient grid resolution, inadequate surface and boundary layer formulations, and the lack of full coupling to a dynamic ocean. The extreme high winds, intense rainfall, large ocean waves, and copious sea spray in hurricanes push the surface-exchange parameters for temperature, water vapor, and momentum into untested regimes. The recent modeling effort is to develop and test a fully coupled atmosphere-wave-ocean modeling system that is capable of resolving the eye and eyewall in a hurricane at ~1 km grid resolution. The new challenges for these very high resolution models are the corresponding physical representations at 1-km scale, including microphysics, sub-grid turbulence parameterization, atmospheric boundary layer, physical processes at the air-sea interface with surface waves among others. The lack of accurate initial conditions for high-resolution hurricane modeling presents another major challenge. Improvements in initial conditions rest on the use of more airborne and remotely sensed observations in high-resolution assimilation systems and on the application of advanced assimilation schemes to hurricanes. This study aimed to provide an overview of these new challenges using high-resolution model simulations of Hurricanes Isabel (2003), Frances (2004), Katrina and Rita (2005) that were observed extensively by two recent field programs, namely, the Coupled Boundary Layer Air-Sea Transfer (CBLAST)-Hurricane in 2003-2004 and the Hurricane Rainbands and Intensity Change Experiment (RAINEX) in 2005.

  13. High resolution microwave spectrometer sounder (HIMSS), volume 1, book 1

    NASA Technical Reports Server (NTRS)

    1990-01-01

    The following topics are presented with respect to the high resolution microwave spectrometer sounder (HIMSS) that is to be used as an instrument for NASA's Earth Observing System (EOS): (1) an instrument overview; (2) an instrument description; (3) the instrument's conceptual design; (4) technical risks and offsets; (5) instrument reliability; (6) commands and telemetry; (7) mass and power budgets; (8) integration and test program; (9) program implementation; and (10) phase CD schedule.

  14. Applications of high-resolution remote sensing image data

    NASA Technical Reports Server (NTRS)

    Strome, W. M.; Leckie, D.; Miller, J.; Buxton, R.

    1990-01-01

    There are many situations in which the image resolution of satellite data is insufficient to provide the detail required for resource management and environmental monitoring. This paper will focus on applications of high-resolution (0.4 to 10 m) airborne multispectral and imaging spectrometer data acquired in Canada using the MEIS II multispectral line imager and the PMI imaging spectrometer. Applications discussed will include forestry, mapping, and geobotany.

  15. Optical alignment of high resolution Fourier transform spectrometers

    NASA Technical Reports Server (NTRS)

    Breckinridge, J. B.; Ocallaghan, F. G.; Cassie, A. G.

    1980-01-01

    Remote sensing, high resolution FTS instruments often contain three primary optical subsystems: Fore-Optics, Interferometer Optics, and Post, or Detector Optics. We discuss the alignment of a double-pass FTS containing a cat's-eye retro-reflector. Also, the alignment of fore-optics containing confocal paraboloids with a reflecting field stop which relays a field image onto a camera is discussed.

  16. High-resolution structure of the native histone octamer

    PubMed Central

    Wood, Christopher M.; Nicholson, James M.; Lambert, Stanley J.; Chantalat, Laurent; Reynolds, Colin D.; Baldwin, John P.

    2005-01-01

    Crystals of native histone octamers (H2A–H2B)–(H4–H3)–(H3′–H4′)–(H2B′–­H2A′) from chick erythrocytes in 2 M KCl, 1.35 M potassium phosphate pH 6.9 diffract X-rays to 1.90 Å resolution, yielding a structure with an R work value of 18.7% and an R free of 22.2%. The crystal space group is P65, the asymmetric unit of which contains one complete octamer. This high-resolution model of the histone-core octamer allows further insight into intermolecular interactions, including water molecules, that dock the histone dimers to the tetramer in the nucleosome-core particle and have relevance to nucleosome remodelling. The three key areas analysed are the H2A′–H3–H4 molecular cluster (also H2A–H3′–H4′), the H4–H2B′ interaction (also H4′–H2B) and the H2A′–H4 β-sheet interaction (also H2A–H4′). The latter of these three regions is important to nucleosome remodelling by RNA polymerase II, as it is shown to be a likely core-histone binding site, and its disruption creates an instability in the nucleosome-core particle. A majority of the water molecules in the high-resolution octamer have positions that correlate to similar positions in the high-­resolution nucleosome-core particle structure, suggesting that the high-resolution octamer model can be used for comparative studies with the high-resolution nucleosome-core particle. PMID:16511091

  17. The Goddard High Resolution Spectrograph: Instrument, goals, and science results

    NASA Technical Reports Server (NTRS)

    Brandt, J. C.; Heap, S. R.; Beaver, E. A.; Boggess, A.; Carpenter, K. G.; Ebbets, D. C.; Hutchings, J. B.; Jura, M.; Leckrone, D. S.; Linsky, J. L.

    1994-01-01

    The Goddard High Resolution Spectrograph (GHRS), currently in Earth orbit on the Hubble Space Telescope (HST), operates in the wavelength range 1150-3200 A with spectral resolutions (lambda/delta lambda) of approximately 2 x 10(exp 3), 2 x 10(exp 4), and 1 x 10(exp 3). The instrument and its development from inception, its current status, the approach to operations, representative results in the major areas of the scientific goals, and prospects for the future are described.

  18. High-resolution imagery applications in the littorals

    NASA Astrophysics Data System (ADS)

    Abileah, Ronald

    2001-12-01

    We focus on three applications of high-resolution imagery in the littorals: mapping bathymetry, monitoring the health of coral reefs, and taking censuses of marine mammals. All three applications show the importance and potential benefits of higher-resolution imagery. Increased radiometric sensitivity and the simultaneous collection of panchromatic and multispectral imagery are also important. An Ikonos image of Maui is used to demonstrate these applications. We also briefly explain some important differences between multispectral remote sensing over water and land.

  19. High-Resolution Wind Measurements for Offshore Wind Energy Development

    NASA Technical Reports Server (NTRS)

    Nghiem, Son V.; Neumann, Gregory

    2011-01-01

    A mathematical transform, called the Rosette Transform, together with a new method, called the Dense Sampling Method, have been developed. The Rosette Transform is invented to apply to both the mean part and the fluctuating part of a targeted radar signature using the Dense Sampling Method to construct the data in a high-resolution grid at 1-km posting for wind measurements over water surfaces such as oceans or lakes.

  20. High resolution fiber optic interferometer: FY94 final report

    SciTech Connect

    Baldwin, D.P.; Zamzow, D.S.; D`Silva, A.P.

    1994-12-31

    Objective is a field, on-line high resolution spectrometer system capable of resolving the optical emission from actinide isotopes in an inductively coupled plasma. AOTF (acousto-optic tunable filter) and FFP (fiber optic Fabry-Perot) were combined in this spectrometer, using bulk optical materials. The AOTF-FFP system was tested on U-235/U-238 and RCRA metals. Future development is described; a commercialization plan is attached.

  1. Adaptive optics with pupil tracking for high resolution retinal imaging.

    PubMed

    Sahin, Betul; Lamory, Barbara; Levecq, Xavier; Harms, Fabrice; Dainty, Chris

    2012-02-01

    Adaptive optics, when integrated into retinal imaging systems, compensates for rapidly changing ocular aberrations in real time and results in improved high resolution images that reveal the photoreceptor mosaic. Imaging the retina at high resolution has numerous potential medical applications, and yet for the development of commercial products that can be used in the clinic, the complexity and high cost of the present research systems have to be addressed. We present a new method to control the deformable mirror in real time based on pupil tracking measurements which uses the default camera for the alignment of the eye in the retinal imaging system and requires no extra cost or hardware. We also present the first experiments done with a compact adaptive optics flood illumination fundus camera where it was possible to compensate for the higher order aberrations of a moving model eye and in vivo in real time based on pupil tracking measurements, without the real time contribution of a wavefront sensor. As an outcome of this research, we showed that pupil tracking can be effectively used as a low cost and practical adaptive optics tool for high resolution retinal imaging because eye movements constitute an important part of the ocular wavefront dynamics.

  2. Quantification of Murine Pancreatic Tumors by High Resolution Ultrasound

    PubMed Central

    Sastra, Stephen A.; Olive, Kenneth P.

    2013-01-01

    Summary Ultrasonography is a powerful imaging modality that enables non-invasive, real time visualization of abdominal organs and tissues. This technology may be adapted for use in mice through the utilization of higher frequency transducers, allowing for extremely high resolution imaging of the mouse pancreas. This technique is particularly well-suited to pancreas imaging due to the ultrasonographic properties of the normal mouse pancreas, easily accessible imaging planes for the head and tail of the mouse pancreas, and the comparative difficulty in imaging the mouse pancreas with other technologies. A suite of measurements tools is available to characterize the normal and diseased states of tissues. Of particular utility for cancer applications is the ability to use tomography to construct a 3D tumor volume, enabling longitudinal imaging studies to track tumor development, or response to therapies. Here, we describe a detailed method for performing high resolution ultrasound to detect and measure pancreatic lesions in a genetically engineered mouse model of pancreatic ductal using the VisualSonics Vevo2100 High Resolution Ultrasound System. The method includes preparation of the animal for imaging, 2D and 3D image acquisition, and post-acquisition analysis of tumors volumes. The combined procedure has been utilized extensively by our group and others for the preclinical evaluation of novel therapeutic agents in the treatment of pancreatic ductal adenocarcinoma (1–4). PMID:23359158

  3. High resolution surface plasmon microscopy for cell imaging

    NASA Astrophysics Data System (ADS)

    Argoul, F.; Monier, K.; Roland, T.; Elezgaray, J.; Berguiga, L.

    2010-04-01

    We introduce a new non-labeling high resolution microscopy method for cellular imaging. This method called SSPM (Scanning Surface Plasmon Microscopy) pushes down the resolution limit of surface plasmon resonance imaging (SPRi) to sub-micronic scales. High resolution SPRi is obtained by the surface plasmon lauching with a high numerical aperture objective lens. The advantages of SPPM compared to other high resolution SPRi's rely on three aspects; (i) the interferometric detection of the back reflected light after plasmon excitation, (ii) the twodimensional scanning of the sample for image reconstruction, (iii) the radial polarization of light, enhancing both resolution and sensitivity. This microscope can afford a lateral resolution of - 150 nm in liquid environment and - 200 nm in air. We present in this paper images of IMR90 fibroblasts obtained with SSPM in dried environment. Internal compartments such as nucleus, nucleolus, mitochondria, cellular and nuclear membrane can be recognized without labelling. We propose an interpretation of the ability of SSPM to reveal high index contrast zones by a local decomposition of the V (Z) function describing the response of the SSPM.

  4. Fabrication High Resolution Metrology Target By Step And Repeat Method

    NASA Astrophysics Data System (ADS)

    Dusa, Mircea

    1983-10-01

    Based on the photolithography process generally used to generate high resolution masks for semiconductor I.C.S, we found a very useful industrial application of laser technology.First, we have generated high resolution metrology targets which are used in industrial measurement laser interferometers as difra.ction gratings. Secondi we have generated these targets using step and repeat machine, with He-Ne laser interferometer controlled state, as a pattern generator, due to suitable computer programming.Actually, high resolution metrology target, means two chromium plates, one of which is called the" rule" the other one the "vernier". In Fig.1 we have the configuration of the rule and the vernier. The rule has a succesion of 3 μM lines generated as a difraction grating on a 4 x 4 inch chromium blank. The vernier has several exposed fields( areas) having 3 - 15 μm lines, fields placed on very precise position on the chromium blank surface. High degree of uniformity, tight CD tolerances, low defect density required by the targets, creates specialised problems during processing. Details of the processing, together with experimental results will be presented. Before we start to enter into process details, we have to point out that the dimensional requirements of the reticle target, are quite similar or perhaps more strict than LSI master casks. These requirements presented in Fig.2.

  5. High resolution ultrasonic spectroscopy system for nondestructive evaluation

    NASA Technical Reports Server (NTRS)

    Chen, C. H.

    1991-01-01

    With increased demand for high resolution ultrasonic evaluation, computer based systems or work stations become essential. The ultrasonic spectroscopy method of nondestructive evaluation (NDE) was used to develop a high resolution ultrasonic inspection system supported by modern signal processing, pattern recognition, and neural network technologies. The basic system which was completed consists of a 386/20 MHz PC (IBM AT compatible), a pulser/receiver, a digital oscilloscope with serial and parallel communications to the computer, an immersion tank with motor control of X-Y axis movement, and the supporting software package, IUNDE, for interactive ultrasonic evaluation. Although the hardware components are commercially available, the software development is entirely original. By integrating signal processing, pattern recognition, maximum entropy spectral analysis, and artificial neural network functions into the system, many NDE tasks can be performed. The high resolution graphics capability provides visualization of complex NDE problems. The phase 3 efforts involve intensive marketing of the software package and collaborative work with industrial sectors.

  6. Machine Learning Based Road Detection from High Resolution Imagery

    NASA Astrophysics Data System (ADS)

    Lv, Ye; Wang, Guofeng; Hu, Xiangyun

    2016-06-01

    At present, remote sensing technology is the best weapon to get information from the earth surface, and it is very useful in geo- information updating and related applications. Extracting road from remote sensing images is one of the biggest demand of rapid city development, therefore, it becomes a hot issue. Roads in high-resolution images are more complex, patterns of roads vary a lot, which becomes obstacles for road extraction. In this paper, a machine learning based strategy is presented. The strategy overall uses the geometry features, radiation features, topology features and texture features. In high resolution remote sensing images, the images cover a great scale of landscape, thus, the speed of extracting roads is slow. So, roads' ROIs are firstly detected by using Houghline detection and buffering method to narrow down the detecting area. As roads in high resolution images are normally in ribbon shape, mean-shift and watershed segmentation methods are used to extract road segments. Then, Real Adaboost supervised machine learning algorithm is used to pick out segments that contain roads' pattern. At last, geometric shape analysis and morphology methods are used to prune and restore the whole roads' area and to detect the centerline of roads.

  7. High resolution, MRI-based, segmented, computerized head phantom

    SciTech Connect

    Zubal, I.G.; Harrell, C.R.; Smith, E.O.; Smith, A.L.; Krischlunas, P.

    1999-01-01

    The authors have created a high-resolution software phantom of the human brain which is applicable to voxel-based radiation transport calculations yielding nuclear medicine simulated images and/or internal dose estimates. A software head phantom was created from 124 transverse MRI images of a healthy normal individual. The transverse T2 slices, recorded in a 256x256 matrix from a GE Signa 2 scanner, have isotropic voxel dimensions of 1.5 mm and were manually segmented by the clinical staff. Each voxel of the phantom contains one of 62 index numbers designating anatomical, neurological, and taxonomical structures. The result is stored as a 256x256x128 byte array. Internal volumes compare favorably to those described in the ICRP Reference Man. The computerized array represents a high resolution model of a typical human brain and serves as a voxel-based anthropomorphic head phantom suitable for computer-based modeling and simulation calculations. It offers an improved realism over previous mathematically described software brain phantoms, and creates a reference standard for comparing results of newly emerging voxel-based computations. Such voxel-based computations lead the way to developing diagnostic and dosimetry calculations which can utilize patient-specific diagnostic images. However, such individualized approaches lack fast, automatic segmentation schemes for routine use; therefore, the high resolution, typical head geometry gives the most realistic patient model currently available.

  8. High-Resolution Angioscopic Imaging During Endovascular Neurosurgery

    PubMed Central

    McVeigh, Patrick Z.; Sacho, Raphael; Weersink, Robert A.; Pereira, Vitor M.; Kucharczyk, Walter; Seibel, Eric J.; Wilson, Brian C.

    2014-01-01

    BACKGROUND: Endoluminal optical imaging, or angioscopy, has not seen widespread application during neurointerventional procedures, largely as a result of the poor imaging resolution of existing angioscopes. Scanning fiber endoscopes (SFEs) are a novel endoscopic platform that allows high-resolution video imaging in an ultraminiature form factor that is compatible with currently used distal access endoluminal catheters. OBJECTIVE: To test the feasibility and potential utility of high-resolution angioscopy with an SFE during common endovascular neurosurgical procedures. METHODS: A 3.7-French SFE was used in a porcine model system to image endothelial disruption, ischemic stroke and mechanical thrombectomy, aneurysm coiling, and flow-diverting stent placement. RESULTS: High-resolution, video-rate imaging was shown to be possible during all of the common procedures tested and provided information that was complementary to standard fluoroscopic imaging. SFE angioscopy was able to assess novel factors such as aneurysm base coverage fraction and side branch patency, which have previously not been possible to determine with conventional angiography. CONCLUSION: Endovascular imaging with an SFE provides important information on factors that cannot be assessed fluoroscopically and is a novel platform on which future neurointerventional techniques may be based because it allows for periprocedural inspection of the integrity of the vascular system and the deployed devices. In addition, it may be of diagnostic use for inspecting the vascular wall and postprocedure device evaluation. ABBREVIATIONS: CFB, coherent fiber bundle F, French SFE, scanning fiber endoscope PMID:24762703

  9. Metallicity determination of M dwarfs. High-resolution infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Lindgren, Sara; Heiter, Ulrike; Seifahrt, Andreas

    2016-02-01

    Context. Several new techniques to determine the metallicity of M dwarfs with better precision have been developed over the last decades. However, most of these studies were based on empirical methods. In order to enable detailed abundance analysis, standard methods established for warmer solar-like stars, i.e. model-dependent methods using fitting of synthetic spectra, still need to be used. Aims: In this work we continue the reliability confirmation and development of metallicity determinations of M dwarfs using high-resolution infrared spectra. The reliability was confirmed through analysis of M dwarfs in four binary systems with FGK dwarf companions and by comparison with previous optical studies of the FGK dwarfs. Methods: The metallicity determination was based on spectra taken in the J band (1.1-1.4 μm) with the CRIRES spectrograph. In this part of the infrared, the density of stellar molecular lines is limited, reducing the amount of blends with atomic lines enabling an accurate continuum placement. Lines of several atomic species were used to determine the stellar metallicity. Results: All binaries show excellent agreement between the derived metallicity of the M dwarf and its binary companion. Our results are also in good agreement with values found in the literature. Furthermore, we propose an alternative way to determine the effective temperature of M dwarfs of spectral types later than M2 through synthetic spectral fitting of the FeH lines in our observed spectra. Conclusions: We have confirmed that a reliable metallicity determination of M dwarfs can be achieved using high-resolution infrared spectroscopy. We also note that metallicites obtained with photometric metallicity calibrations available for M dwarfs only partly agree with the results we obtain from high-resolution spectroscopy. Based on data obtained at ESO-VLT, Paranal Observatory, Chile, Program ID 082.D-0838(A) and 084.D-1042(A).

  10. High-resolution extended source optical coherence tomography.

    PubMed

    Yu, Xiaojun; Liu, Xinyu; Chen, Si; Luo, Yuemei; Wang, Xianghong; Liu, Linbo

    2015-10-01

    High resolution optical coherence tomography (OCT) is capable of providing detailed tissue microstructures that are critical for disease diagnosis, yet its sensitivity is usually degraded since the system key components are typically not working at their respective center wavelengths. We developed a novel imaging system that achieves enhanced sensitivity without axial resolution degradation by the use of a spectrally encoded extended source (SEES) technique; it allows larger sample power without exceeding the maximum permissible exposure (MPE). In this study, we demonstrate a high-resolution extended source (HRES) OCT system, which is capable of providing a transverse resolution of 4.4 µm and an axial resolution of 2.1 µm in air with the SEES technique. We first theoretically show a sensitivity advantage of 6-dB of the HRES-OCT over that of its point source counterpart using numerical simulations, and then experimentally validate the applicability of the SEES technique to high-resolution OCT (HR-OCT) by comparing the HRES-OCT with an equivalent point-source system. In the HRES-OCT system, a dispersive prism was placed in the infinity space of the sample arm optics to spectrally extend the visual angle (angular subtense) of the light source to 10.3 mrad. This extended source allowed ~4 times larger MPE than its point source counterpart, which results in an enhancement of ~6 dB in sensitivity. Specifically, to solve the unbalanced dispersion between the sample and the reference arm optics, we proposed easy and efficient methods for system calibration and dispersion correction, respectively. With a maximum scanning speed reaching up to 60K A-lines/s, we further conducted imaging experiments with HRES-OCT using the human fingertip in vivo and the swine eye tissues ex vivo. Results demonstrate that the HRES-OCT is able to achieve significantly larger penetration depth than its conventional point source OCT counterpart.

  11. Proceedings of the workshop on high resolution computed microtomography (CMT)

    SciTech Connect

    1997-02-01

    The purpose of the workshop was to determine the status of the field, to define instrumental and computational requirements, and to establish minimum specifications required by possible users. The most important message sent by implementers was the remainder that CMT is a tool. It solves a wide spectrum of scientific problems and is complementary to other microscopy techniques, with certain important advantages that the other methods do not have. High-resolution CMT can be used non-invasively and non-destructively to study a variety of hierarchical three-dimensional microstructures, which in turn control body function. X-ray computed microtomography can also be used at the frontiers of physics, in the study of granular systems, for example. With high-resolution CMT, for example, three-dimensional pore geometries and topologies of soils and rocks can be obtained readily and implemented directly in transport models. In turn, these geometries can be used to calculate fundamental physical properties, such as permeability and electrical conductivity, from first principles. Clearly, use of the high-resolution CMT technique will contribute tremendously to the advancement of current R and D technologies in the production, transport, storage, and utilization of oil and natural gas. It can also be applied to problems related to environmental pollution, particularly to spilling and seepage of hazardous chemicals into the Earth's subsurface. Applications to energy and environmental problems will be far-ranging and may soon extend to disciplines such as materials science--where the method can be used in the manufacture of porous ceramics, filament-resin composites, and microelectronics components--and to biomedicine, where it could be used to design biocompatible materials such as artificial bones, contact lenses, or medication-releasing implants. Selected papers are indexed separately for inclusion in the Energy Science and Technology Database.

  12. High resolution Arctic snow observations: SnowNet (Invited)

    NASA Astrophysics Data System (ADS)

    Hiemstra, C. A.; Sturm, M.; Gelvin, A. B.; Berezovskaya, S.; Saari, S. P.; Finnegan, D. C.; Liston, G. E.

    2009-12-01

    Snow’s importance has become especially prominent in the terrestrial Arctic, where snow dominates the landscape most of the year and changes in snow arrival, depth, and melt have substantial energy budget and biotic consequences. Yet, the Arctic presents formidable challenges to accurate snow measurements because snow depths can vary greatly over relatively short distances (< 10 m). Snow distribution patterns in windy environments, such as the Arctic, arise from interactions among wind, snow, vegetation, and topography. In this environment, snow is transported easily and is retained in topographic depressions, near taller vegetation, and deposited on the lee sides of hills. Reliable observations of where snow exists in the Arctic landscape can be difficult to obtain, and estimates vary depending on where snow is sampled. Measurements tend to be widely distributed and sparse. In addition, observed changes in Arctic vegetation (e.g., increasing shrubs) and land surfaces (e.g., thermokarst) complicate matters further. In response to this critical shortcoming in Arctic snow measurements, we have developed a prototype observational network (SnowNet) that employs standard meteorological observations and high resolution topographic and vegetation data in concert with a comprehensive spatially-intensive snow measurement program. Our sites at Barrow (started 2007) and Imnavait Creek (started 2008), Alaska, feature frequent site visits and intensive spatial sampling of snow depths and densities and snow-surface topography. Both sites have high resolution (~20 cm) topographic and vegetation data layers generated from remote sensing and ground surveys. Further, we have been incorporating extremely high-resolution (< 10 cm) ground-based LiDAR snow and vegetation datasets that allow us to identify relationships among topography, vegetation, and snow in Arctic environments. In addition, we have collected tens of thousands of manual snow depths across our research sites. This

  13. Large-field high-resolution mosaic movies

    NASA Astrophysics Data System (ADS)

    Hammerschlag, Robert H.; Sliepen, Guus; Bettonvil, Felix C. M.; Jägers, Aswin P. L.; Sütterlin, Peter; Martin, Sara F.

    2012-09-01

    Movies with fields-of-view larger than normal for high-resolution telescopes will give a better understanding of processes on the Sun, such as filament and active region developments and their possible interactions. New active regions can influence, by their emergence, their environment to the extent of possibly serving as an igniter of the eruption of a nearby filament. A method to create a large field-of-view is to join several fields-of-view into a mosaic. Fields are imaged quickly one after another using fast telescope-pointing. Such a pointing cycle has been automated at the Dutch Open Telescope (DOT), a high-resolution solar telescope located on the Canary Island La Palma. The observer can draw with the computer mouse the desired total field in the guider-telescope image of the whole Sun. The guider telescope is equipped with an H-alpha filter and electronic enhancement of contrast in the image for good visibility of filaments and prominences. The number and positions of the subfields are calculated automatically and represented by an array of bright points indicating the subfield centers inside the drawn rectangle of the total field on the computer screen with the whole-sun image. When the exposures start the telescope repeats automatically the sequence of subfields. Automatic production of flats is also programmed including defocusing and fast motion over the solar disk of the image field. For the first time mosaic movies were programmed from stored information on automated telescope motions from one field to the next. The mosaic movies fill the gap between whole-sun images with limited resolution of synoptic telescopes including space instruments and small-field high-cadence movies of high-resolution solar telescopes.

  14. Multispectral high-resolution hologram generation using orthographic projection images

    NASA Astrophysics Data System (ADS)

    Muniraj, I.; Guo, C.; Sheridan, J. T.

    2016-08-01

    We present a new method of synthesizing a digital hologram of three-dimensional (3D) real-world objects from multiple orthographic projection images (OPI). A high-resolution multiple perspectives of 3D objects (i.e., two dimensional elemental image array) are captured under incoherent white light using synthetic aperture integral imaging (SAII) technique and their OPIs are obtained respectively. The reference beam is then multiplied with the corresponding OPI and integrated to form a Fourier hologram. Eventually, a modified phase retrieval algorithm (GS/HIO) is applied to reconstruct the hologram. The principle is validated experimentally and the results support the feasibility of the proposed method.

  15. High-Resolution, Wide-Field-of-View Scanning Telescope

    NASA Technical Reports Server (NTRS)

    Sepulveda, Cesar; Wilson, Robert; Seshadri, Suresh

    2007-01-01

    A proposed telescope would afford high resolution over a narrow field of view (<0.10 ) while scanning over a total field of view nominally 16 wide without need to slew the entire massive telescope structure. The telescope design enables resolution of a 1-m-wide object in a 50- km-wide area of the surface of the Earth as part of a 200-km-wide area field of view monitored from an orbit at an altitude of 700 km. The conceptual design of this telescope could also be adapted to other applications both terrestrial and extraterrestrial in which there are requirements for telescopes that afford both wide- and narrow-field capabilities. In the proposed telescope, the scanning would be effected according to a principle similar to that of the Arecibo radio telescope, in which the primary mirror is stationary with respect to the ground and a receiver is moved across the focal surface of the primary mirror. The proposed telescope would comprise (1) a large spherical primary mirror that would afford high resolution over a narrow field of view and (2) a small displaceable optical relay segment that would be pivoted about the center of an aperture stop to effect the required scanning (see figure). Taken together, both comprise a scanning narrow-angle telescope that does not require slewing the telescope structure. In normal operation, the massive telescope structure would stare at a fixed location on the ground. The inner moveable relay optic would be pivoted to scan the narrower field of view over the wider one, making it possible to retain a fixed telescope orientation, while obtaining high-resolution images over multiple target areas during an interval of 3 to 4 minutes in the intended orbit. The pivoting relay segment of the narrow-angle telescope would include refractive and reflective optical elements, including two aspherical mirrors, to counteract the spherical aberration of the primary mirror. Overall, the combination of the primary mirror and the smaller relay optic

  16. High resolution upgrade of the ATF damping ring BPM system

    SciTech Connect

    Terunuma, N.; Urakawa, J.; Frisch, J.; May, J.; McCormick, D.; Nelson, J.; Seryi, A.; Smith, T.; Woodley, M.; Briegel, C.; Dysert, R.; /Fermilab

    2008-05-01

    A beam position monitor (BPM) upgrade at the KEK Accelerator Test Facility (ATF) damping ring has been accomplished in its first stage, carried out by a KEK/FNAL/SLAC collaboration under the umbrella of the global ILC R&D effort. The upgrade consists of a high resolution, high reproducibility read-out system, based on analog and digital downconversion techniques, digital signal processing, and also tests a new automatic gain error correction schema. The technical concept and realization, as well as preliminary results of beam studies are presented.

  17. High-Resolution Spectroscopy of Some Very Inactive Southern Stars

    NASA Astrophysics Data System (ADS)

    Villarreal, A.; King, J. R.; Soderblom, D. R.; Henry, T. J.

    2001-12-01

    We have obtained high-resolution echelle spectra of a few dozen solar-type stars that an earlier low resolution Ca II H & K survey suggested have modest evels of chromospheric activity. We present Hα -based chromospheric activity measures, binarity information, and Li abundances of the sample. As expected, our spectra: confirm the low levels of chromospheric activity; suggest that these objects are apparently single; indicate the stars have small projected rotational velocities; and yield low photospheric abundances of Li. This work was supported by NSF grant AST-0086576 to JRK.

  18. High resolution collimator system for X-ray detector

    DOEpatents

    Eberhard, Jeffrey W.; Cain, Dallas E.

    1987-01-01

    High resolution in an X-ray computerized tomography (CT) inspection system is achieved by using a collimator/detector combination to limit the beam width of the X-ray beam incident on a detector element to the desired resolution width. In a detector such as a high pressure Xenon detector array, a narrow tapered collimator is provided above a wide detector element. The collimator slits have any desired width, as small as a few mils at the top, the slit width is easily controlled, and they are fabricated on standard machines. The slit length determines the slice thickness of the CT image.

  19. Measurement of stratospheric HBr using high resolution far infrared spectroscopy

    NASA Astrophysics Data System (ADS)

    Carlotti, M.; Ade, P. A. R.; Carli, B.; Ciarpallini, P.; Cortesi, U.; Griffin, M. J.; Lepri, G.; Mencaraglia, F.; Murray, A. G.; Nolt, I. G.; Park, J. H.; Radostitz, J. V.

    Far infrared spectral features of HBr have been observed in the stratospheric emission spectrum using a balloon borne high resolution Fourier transform spectrometer equipped with a high sensitivity detector specially designed for this purpose. The value of 1.6±0.6 parts per trillion in volume for the HBr mixing ratio has been retrieved, from the global-fit analysis of 121 spectra, in the 25-36.5 km altitude range. The result is briefly compared with models and previous assessments.

  20. High-resolution speckle imaging through strong atmospheric turbulence.

    PubMed

    Hope, Douglas A; Jefferies, Stuart M; Hart, Michael; Nagy, James G

    2016-05-30

    We demonstrate that high-resolution imaging through strong atmospheric turbulence can be achieved by acquiring data with a system that captures short exposure ("speckle") images using a range of aperture sizes and then using a bootstrap multi-frame blind deconvolution restoration process that starts with the smallest aperture data. Our results suggest a potential paradigm shift in how we image through atmospheric turbulence. No longer should image acquisition and post processing be treated as two independent processes: they should be considered as intimately related.

  1. High-resolution Brillouin analysis of composite materials beams

    NASA Astrophysics Data System (ADS)

    London, Yosef; Antman, Yair; Silbiger, Maayan; Efraim, Liel; Froochzad, Avihay; Adler, Gadi; Levenberg, Eyal; Zadok, Avi

    2015-09-01

    High-resolution Brillouin optical correlation domain analysis of fibers embedded within beams of composite materials is performed with 4 cm resolution and 0.5 MHz sensitivity. Two new contributions are presented. First, analysis was carried out continuously over 30 hours following the production of a beam, observing heating during exothermal curing and buildup of residual strains. Second, the bending stiffness and Young's modulus of the composite beam were extracted based on distributed strain measurements, taken during a static three-point bending experiment. The calculated parameters were used to forecast the beam deflections. The latter were favorably compared against external displacement measurements.

  2. Coregistration of high-resolution Mars orbital images

    NASA Astrophysics Data System (ADS)

    Sidiropoulos, Panagiotis; Muller, Jan-Peter

    2015-04-01

    The systematic orbital imaging of the Martian surface started 4 decades ago from NASA's Viking Orbiter 1 & 2 missions, which were launched in August 1975, and acquired orbital images of the planet between 1976 and 1980. The result of this reconnaissance was the first medium-resolution (i.e. ≤ 300m/pixel) global map of Mars, as well as a variety of high-resolution images (reaching up to 8m/pixel) of special regions of interest. Over the last two decades NASA has sent 3 more spacecraft with onboard instruments for high-resolution orbital imaging: Mars Global Surveyor (MGS) having onboard the Mars Orbital Camera - Narrow Angle (MOC-NA), Mars Odyssey having onboard the Thermal Emission Imaging System - Visual (THEMIS-VIS) and the Mars Reconnaissance Orbiter (MRO) having on board two distinct high-resolution cameras, Context Camera (CTX) and High-Resolution Imaging Science Experiment (HiRISE). Moreover, ESA has the multispectral High resolution Stereo Camera (HRSC) onboard ESA's Mars Express with resolution up to 12.5m since 2004. Overall, this set of cameras have acquired more than 400,000 high-resolution images, i.e. with resolution better than 100m and as fine as 25 cm/pixel. Notwithstanding the high spatial resolution of the available NASA orbital products, their accuracy of areo-referencing is often very poor. As a matter of fact, due to pointing inconsistencies, usually form errors in roll attitude, the acquired products may actually image areas tens of kilometers far away from the point that they are supposed to be looking at. On the other hand, since 2004, the ESA Mars Express has been acquiring stereo images through the High Resolution Stereo Camera (HRSC), with resolution that is usually 12.5-25 metres per pixel. The achieved coverage is more than 64% for images with resolution finer than 20 m/pixel, while for ~40% of Mars, Digital Terrain Models (DTMs) have been produced with are co-registered with MOLA [Gwinner et al., 2010]. The HRSC images and DTMs

  3. A High Resolution Microprobe Study of EETA79001 Lithology C

    NASA Technical Reports Server (NTRS)

    Schrader, Christian M.; Cohen, B. A.; Donovan, J. J.; Vicenzi, E. P.

    2010-01-01

    Antarctic meteorite EETA79001 has received substantial attention for possibly containing a component of Martian soil in its impact glass (Lithology C) [1]. The composition of Martian soil can illuminate near-surface processes such as impact gardening [2] and hydrothermal and volcanic activity [3,4]. Impact melts in meteorites represent our most direct samples of Martian regolith. We present the initial findings from a high-resolution electron microprobe study of Lithology C from Martian meteorite EETA79001. As this study develops we aim to extract details of a potential soil composition and to examine Martian surface processes using elemental ratios and correlations.

  4. Homology Groups of High-Resolution Temporal Rainfall

    NASA Astrophysics Data System (ADS)

    Vásquez Aguilar, R.; Carsteanu, A. A.

    2015-12-01

    Using high-resolution temporal rainfall intensities from Iowa City, IA (IIHR, U of Iowa), we perform an analysis of the homology groups generated by data connectivity in state space, and attempt a qualitative interpretation of the first and second homology groups. Let us note that homology groups are generated, in the context of topological data analysis (TDA), by representing the data in n-dimensional state space and building a connectivity diagram according to the respective distances between the data points. Subsequently, the topological invariants of the resulting connected structures are being analyzed.

  5. High-resolution continuum observations of the Sun

    NASA Technical Reports Server (NTRS)

    Zirin, Harold

    1987-01-01

    The aim of the PFI or photometric filtergraph instrument is to observe the Sun in the continuum with as high resolution as possible and utilizing the widest range of wavelengths. Because of financial and political problems the CCD was eliminated so that the highest photometric accuracy is only obtainable by comparison with the CFS images. Presently there is a limitation to wavelengths above 2200 A due to the lack of sensitivity of untreated film below 2200 A. Therefore the experiment at present consists of a film camera with 1000 feet of film and 12 filters. The PFI experiments are outlined using only two cameras. Some further problems of the experiment are addressed.

  6. Design of a High Resolution Hexapod Positioning Mechanism

    NASA Technical Reports Server (NTRS)

    Britt, Jamie

    2001-01-01

    This paper describes the development of a high resolution, six-degree of freedom positioning mechanism. This mechanism, based on the Stewart platform concept, was designed for use with the Developmental Comparative Active Optics Telescope Testbed (DCATT), a ground-based technology testbed for the Next Generation Space Telescope (NGST). The mechanism provides active control to the DCATT telescope's segmented primary mirror. Emphasis is on design decisions and technical challenges. Significant issues include undesirable motion properties of PZT-inchworm actuators, testing difficulties, dimensional stability, and use of advanced composite materials. Supporting test data from prototype mechanisms is presented.

  7. Design of a High Resolution Hexapod Positioning Mechanism

    NASA Technical Reports Server (NTRS)

    Britt, Jamie; Brodeur, Stephen J. (Technical Monitor)

    2001-01-01

    This paper describes the development of a high resolution, six-degree of freedom positioning mechanism. This mechanism, based on the Stewart platform concept, was designed for use with the Developmental Comparative Active Optics Telescope Testbed (DCATT), a ground-based technology testbed for the Next Generation Space Telescope (NGST). The mechanism provides active control to the DCATT telescope's segmented primary mirror. Emphasis is on design decisions and technical challenges. Significant issues include undesirable motion properties of PZT-inchworm actuators, testing difficulties, dimensional stability and use of advanced composite materials. Supporting test data from prototype mechanisms is presented.

  8. High-resolution (30 m) lunar radar images

    NASA Technical Reports Server (NTRS)

    Zisk, Stanley H.

    1988-01-01

    New high-resolution radar images of the lunar surface are being produced using the Haystack Observatory range-Doppler radar system. The goals are to: investigate the decameter-scale properties of the lunar surface, as an aid in the understanding of the geophysical history of the moon; and to improve the understanding of the mechanisms of planetary radar backscattering, to aid in the interpretation of the coarser-resolution images which were and will be obtained from planetary probe missions and other earth-based observations.

  9. Saturn - high-resolution filtered image of Enceladus

    NASA Technical Reports Server (NTRS)

    1981-01-01

    This high-resolution filtered image of Enceladus was made from several images obtained Aug. 25 by Voyager 2 from a range of 119,000 kilometers (74,000 miles). It shows further surface detail on this Saturnian moon (also viewed in the accompanying release P-23955C/BW, S-2-50, imaged about the same time). Enceladus is seen to resemble Jupiter's Galilean satellite Ganymede, which is, however, about 10 times larger. Faintly visible here in 'Saturnshine' is the hemisphere turned away from the sun. The Voyager project is managed for NASA by the Jet Propulsion Laboratory, Pasadena, Calif.

  10. Alternative high-resolution lithographic technologies for optical applications

    NASA Astrophysics Data System (ADS)

    Zeitner, Uwe D.; Weichelt, Tina; Bourgin, Yannick; Kinder, Robert

    2016-03-01

    Modern optical applications have special demands on the lithographic fabrication technologies. This relates to the lateral shape of the structures as well as to their three dimensional surface profile. On the other hand optical nano-structures are often periodic which allows for the use of dedicated lithographic exposure principles. The paper briefly reviews actual developments in the field of optical nano-structure generation. Special emphasis will be given to two technologies: electron-beam lithography based on a flexible cell-projection method and the actual developments in diffractive mask aligner lithography. Both offer a cost effective fabrication alternative for high resolution structures or three-dimensional optical surface profiles.

  11. High-resolution satellite imagery for mesoscale meteorological studies

    NASA Technical Reports Server (NTRS)

    Johnson, David B.; Flament, Pierre; Bernstein, Robert L.

    1994-01-01

    In this article high-resolution satellite imagery from a variety of meteorological and environmental satellites is compared. Digital datasets from Geostationary Operational Environmental Satellite (GOES), National Oceanic and Atmospheric Administration (NOAA), Defense Meteorological Satellite Program (DMSP), Landsat, and Satellite Pour l'Observation de la Terre (SPOT) satellites were archived as part of the 1990 Hawaiian Rainband Project (HaRP) and form the basis of the comparisons. During HaRP, GOES geostationary satellite coverage was marginal, so the main emphasis is on the polar-orbiting satellites.

  12. High-resolution CT findings in pulmonary hyalinizing granuloma.

    PubMed

    Shibata, Yoshihiro; Kobayashi, Takeshi; Hattori, Yuki; Matsui, Osamu; Gabata, Toshifumi; Tamori, Shunichi; Minato, Hiroshi; Ohta, Yasuhiko

    2007-11-01

    A 47-year-old man with pulmonary hyalinizing granuloma is herein presented. The patient, whose chief complaint was a mild cough, was found by chest radiograph to have multiple bilateral nodules. Subsequent high-resolution computed tomography demonstrated multiple slightly irregular nodules, perinodular ground-glass opacity, peribronchovascular interstitial thickening, and cysts. A mild enlargement of systemic lymph nodes was also noted. Laboratory tests disclosed a slight elevation in the C-reactive protein, gamma-globulin, interleukin-6, and soluble interleukin-2 receptor levels. A histopathologic examination of the specimen yielded from a thoracoscopic lung biopsy resulted in a definite diagnosis of pulmonary hyalinizing granuloma. PMID:18043399

  13. Nowcasting for a high-resolution weather radar network

    NASA Astrophysics Data System (ADS)

    Ruzanski, Evan

    Short-term prediction (nowcasting) of high-impact weather events can lead to significant improvement in warnings and advisories and is of great practical importance. Nowcasting using weather radar reflectivity data has been shown to be particularly useful. The Collaborative Adaptive Sensing of the Atmosphere (CASA) radar network provides high-resolution reflectivity data amenable to producing valuable nowcasts. The high-resolution nature of CASA data requires the use of an efficient nowcasting approach, which necessitated the development of the Dynamic Adaptive Radar Tracking of Storms (DARTS) and sinc kernel-based advection nowcasting methodology. This methodology was implemented operationally in the CASA Distributed Collaborative Adaptive Sensing (DCAS) system in a robust and efficient manner necessitated by the high-resolution nature of CASA data and distributed nature of the environment in which the nowcasting system operates. Nowcasts up to 10 min to support emergency manager decision-making and 1--5 min to steer the CASA radar nodes to better observe the advecting storm patterns for forecasters and researchers are currently provided by this system. Results of nowcasting performance during the 2009 CASA IP experiment are presented. Additionally, currently state-of-the-art scale-based filtering methods were adapted and evaluated for use in the CASA DCAS to provide a scale-based analysis of nowcasting. DARTS was also incorporated in the Weather Support to Deicing Decision Making system to provide more accurate and efficient snow water equivalent nowcasts for aircraft deicing decision support relative to the radar-based nowcasting method currently used in the operational system. Results of an evaluation using data collected from 2007--2008 by the Weather Service Radar-1988 Doppler (WSR-88D) located near Denver, Colorado, and the National Center for Atmospheric Research Marshall Test Site near Boulder, Colorado, are presented. DARTS was also used to study the

  14. Clickstream data yields high-resolution maps of science

    SciTech Connect

    Bollen, Johan; Van De Sompel, Herbert; Hagberg, Aric; Bettencourt, Luis; Chute, Ryan; Rodriguez, Marko A; Balakireva, Lyudmila

    2009-01-01

    Intricate maps of science have been created from citation data to visualize the structure of scientific activity. However, most scientific publications are now accessed online. Scholarly web portals record detailed log data at a scale that exceeds the number of all existing citations combined. Such log data is recorded immediately upon publication and keeps track of the sequences of user requests (clickstreams) that are issued by a variety of users across many different domains. Given these advantagees of log datasets over citation data, we investigate whether they can produce high-resolution, more current maps of science.

  15. High Resolution Spectroscopy and Imaging of Hot Astrophysical Plasmas

    NASA Astrophysics Data System (ADS)

    Kowalski, M. P.; Cruddace, R. G.; Gursky, H.; Yentis, D. J.; Barbee, T. W., Jr.; Goldstein, W. H.; Kordas, J. F.; Fritz, G. G.; Barstow, M. A.; Bannister, N. P.; Lapington, J. S.

    2001-12-01

    Future X-ray and EUV missions should include high-resolution spectrometers, permitting use of the full range of spectroscopic diagnostics, in particular measurement of line profiles and Doppler shifts. We present a design for such an instrument (APEX), which would fly on a Small Explorer Satellite and which employs multilayer-coated ion-etched gratings in a normal-incidence configuration. We have already flown successfully a prototype spectrometer (J-PEX) on a NASA sounding rocket. The resulting EUV spectrum of the white dwarf G191-B2B will be presented.

  16. Design and test of a High-Resolution EUV Spectroheliometer

    NASA Technical Reports Server (NTRS)

    Berger, Thomas E.; Timothy, J. G.; Walker, Arthur B. C., Jr.; Kirby, Helen; Morgan, Jeffrey S.; Jain, Surendra K.; Saxena, Ajay K.; Bhattacharyya, Jagadish C.; Huber, Martin C. E.; Tondello, Giuseppe

    1992-01-01

    The HiRES High-Resolution EUV Spectroheliometer is a sounding rocket instrument yielding very high spatial, spectral, and temporal resolution images of the solar outer atmosphere, on the basis of a 45-cm Gregorian telescope feeding a normal-incidence stigmatic EUV spectrometer with imaging multianode microchannel-array detector system, as well as an IR spectrometer with imaging CCD detector system. Attention is given to the expected performance of this system, including the effects of vibrational misalignments due to the sounding rocket flight environment.

  17. High resolution infrared datasets useful for validating stratospheric models

    NASA Technical Reports Server (NTRS)

    Rinsland, Curtis P.

    1992-01-01

    An important objective of the High Speed Research Program (HSRP) is to support research in the atmospheric sciences that will improve the basic understanding of the circulation and chemistry of the stratosphere and lead to an interim assessment of the impact of a projected fleet of High Speed Civil Transports (HSCT's) on the stratosphere. As part of this work, critical comparisons between models and existing high quality measurements are planned. These comparisons will be used to test the reliability of current atmospheric chemistry models. Two suitable sets of high resolution infrared measurements are discussed.

  18. Computing with high-resolution upwind schemes for hyperbolic equations

    NASA Technical Reports Server (NTRS)

    Chakravarthy, S. R.; Osher, S.

    1985-01-01

    Computational aspects of modern high-resolution upwind finite-difference schemes for hyperbolic systems of conservation laws are examined. An operational unification is demonstrated for constructing a wide class of flux-difference-split and flux-split schemes based on the design principles underlying total variation diminishing (TVD) schemes. Consideration is also given to TVD scheme design by preprocessing, the extension of preprocessing and postprocessing approaches to general control volumes, the removal of expansion shocks and 'glitches', relaxation methods for implicit TVD schemes, and a new family of high-accuracy TVD schemes.

  19. Applied high resolution geophysical methods: Offshore geoengineering hazards

    SciTech Connect

    Trabant, P.K.

    1984-01-01

    This book is an examination of the purpose, methodology, equipment, and data interpretation of high-resolution geophysical methods, which are used to assess geological and manmade engineering hazards at offshore construction locations. It is a state-of-the-art review. Contents: 1. Introduction. 2. Maring geophysics, an overview. 3. Marine geotechnique, an overview. 4. Echo sounders. 5. Side scan sonar. 6. Subbottom profilers. 7. Seismic sources. 8. Single-channel seismic reflection systems. 9. Multifold acquisition and digital processing. 10. Marine magnetometers. 11. Marine geoengineering hazards. 12. Survey organization, navigation, and future developments. Appendix. Glossary. References. Index.

  20. High-resolution MR neurography of diffuse peripheral nerve lesions.

    PubMed

    Thawait, S K; Chaudhry, V; Thawait, G K; Wang, K C; Belzberg, A; Carrino, J A; Chhabra, A

    2011-09-01

    High-resolution MR imaging of peripheral nerves is becoming more common and practical with the increasing availability of 3T magnets. There are multiple reports of MR imaging of peripheral nerves in compression and entrapment neuropathies. However, there is a relative paucity of literature on MRN appearance of diffuse peripheral nerve lesions. We attempted to highlight the salient imaging features of myriad diffuse peripheral nerve disorders and imaging techniques for MRN. Using clinical and pathologically proved relevant examples, we present the MRN appearance of various types of diffuse peripheral nerve lesions, such as traumatic, inflammatory, infectious, hereditary, radiation-induced, neoplastic, and tumor variants. PMID:20966057