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  • 1
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    Laboratory multiple-crystal X-ray topography and reciprocal-space mapping of protein crystals: influence of impurities on crystal perfection (2001)
    In:  Other Sources
    Details
    Publication Date: 2011-08-24
    Description: Double-axis multiple-crystal X-ray topography, rocking-curve measurements and triple-axis reciprocal-space mapping have been combined to characterize protein crystals using a laboratory source. Crystals of lysozyme and lysozyme crystals doped with acetylated lysozyme impurities were examined. It was shown that the incorporation of acetylated lysozyme into crystals of lysozyme induces mosaic domains that are responsible for the broadening and/or splitting of rocking curves and diffraction-space maps along the direction normal to the reciprocal-lattice vector, while the overall elastic lattice strain of the impurity-doped crystals does not appear to be appreciable in high angular resolution reciprocal-space maps. Multiple-crystal monochromatic X-ray topography, which is highly sensitive to lattice distortions, was used to reveal the spatial distribution of mosaic domains in crystals which correlates with the diffraction features in reciprocal space. Discussions of the influence of acetylated lysozyme on crystal perfection are given in terms of our observations.
    Keywords: Life Sciences (General)
    Type: Acta crystallographica. Section D, Biological crystallography (ISSN 0907-4449); Volume 57; Pt 6; 840-6
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  • 2
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    Diffraction and imaging study of imperfections of crystallized lysozyme with coherent X-rays (2004)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Phase-contrast X-ray diffraction imaging and high-angular-resolution diffraction combined with phase-contrast radiographic imaging were employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in the symmetric Laue case. The full-width at half-maximum (FWHM) of a 4 4 0 rocking curve measured from the original crystal was approximately 16.7 arcsec and imperfections including line defects, inclusions and other microdefects were observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the 〈1 1 0〉 growth front and have been found to originate mostly in a central growth area and occasionally in outer growth regions. Inclusions of impurities or formations of foreign particles in the central growth region are resolved in the images with high sensitivity to defects. Slow dehydration led to the broadening of a fairly symmetric 4 4 0 rocking curve by a factor of approximately 2.6, which was primarily attributed to the dehydration-induced microscopic effects that are clearly shown in X-ray diffraction images. The details of the observed defects and the significant change in the revealed microstructures with drying provide insight into the nature of imperfections, nucleation and growth, and the properties of protein crystals.
    Keywords: Life Sciences (General)
    Type: Acta crystallographica. Section D, Biological crystallography (ISSN 0907-4449); Volume 60; Pt 4; 621-9
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  • 3
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    Phase sensitive x-ray diffraction imaging of defects in biological macromolecular crystals (2001)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: Conventional x-ray diffraction topography is currently used to map defects in the bulk of protein crystals, but the lack of sufficient contrast is frequently a limiting factor. We experimentally demonstrate that this barrier can be circumvented using a method that combines phase sensitive and diffraction imaging principles. Details of defects revealed in tetragonal lysozyme and cubic ferritin crystals are presented and discussed. The approach enabling the detection of the phase changes of diffracted x rays should prove to be useful in the study of defect structures in a broad range of biological macromolecular crystals.
    Keywords: Life Sciences (General)
    Type: Physical review letters (ISSN 0031-9007); Volume 87; 14; 148101
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  • 4
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    Quality factors for alpha particles emitted in tissue (2002)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A concept of a mean or dose averaged quality factor was defined in ICRP Publication 26 using relationships for quality factor as a function of LET. The concept of radiation weighting factors, wR, was introduced in ICRP Publication 60 in 1990. These are meant to be generalized factors that modify absorbed dose to reflect the risk of stochastic effects as a function of the quality of the radiation incident on the body or emitted by radioactivity within the body. The values of wr are equal to 20 for all alpha particles externally or internally emitted. This note compares the dose averaged quality factor for alpha particles originating in tissue using the old and revised recommendations for quality factor as a function of LET. The dose averaged quality factor never exceeds 20 using the old recommendations and is never less than 20 with the revised recommendations.
    Keywords: Life Sciences (General)
    Type: Health physics (ISSN 0017-9078); Volume 82; 1; 102-4
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  • 5
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    Predicting Turbulent Convective Heat Transfer in Fully Developed Duct Flows (2001)
    In:  Other Sources
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    Publication Date: 2011-08-23
    Description: The performance of an explicit algebraic stress model (EASM) is assessed in predicting the turbulent flow and forced heat transfer in both straight and wavy ducts, with rectangular, trapezoidal and triangular cross-sections, under fully developed conditions. A comparison of secondary flow patterns. including velocity vectors and velocity and temperature contours, are shown in order to study the effect of waviness on flow dynamics, and comparisons between the hydraulic parameters. Fanning friction factor and Nusselt number, are also presented. In all cases. isothermal conditions are imposed on the duct walls, and the turbulent heat fluxes are modeled using gradient-diffusion type models. The formulation is valid for Reynolds numbers up to 10(exp 5) and this minimizes the need for wall functions that have been used with mixed success in previous studies of complex duct flows. In addition, the present formulation imposes minimal demand on the number of grid points without any convergence or stability problems. Criteria in terms of heat transfer and friction factor needed to choose the optimal wavy duct cross-section for industrial applications among the ones considered are discussed.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: International Journal of Heat and Fluid Flow (ISSN 0142-727X); Volume 22; 381-392
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  • 6
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    Testing Conducted for Lithium-Ion Cell and Battery Verification (2004)
    In:  CASI
    Details
    Publication Date: 2018-06-05
    Description: The NASA Glenn Research Center has been conducting in-house testing in support of NASA's Lithium-Ion Cell Verification Test Program, which is evaluating the performance of lithium-ion cells and batteries for NASA mission operations. The test program is supported by NASA's Office of Aerospace Technology under the NASA Aerospace Flight Battery Systems Program, which serves to bridge the gap between the development of technology advances and the realization of these advances into mission applications. During fiscal year 2003, much of the in-house testing effort focused on the evaluation of a flight battery originally intended for use on the Mars Surveyor Program 2001 Lander. Results of this testing will be compared with the results for similar batteries being tested at the Jet Propulsion Laboratory, the Air Force Research Laboratory, and the Naval Research Laboratory. Ultimately, this work will be used to validate lithium-ion battery technology for future space missions. The Mars Surveyor Program 2001 Lander battery was characterized at several different voltages and temperatures before life-cycle testing was begun. During characterization, the battery displayed excellent capacity and efficiency characteristics across a range of temperatures and charge/discharge conditions. Currently, the battery is undergoing lifecycle testing at 0 C and 40-percent depth of discharge under low-Earth-orbit (LEO) conditions.
    Keywords: Spacecraft Propulsion and Power
    Type: Research and Technology 2003; NASA/TM-2004-212729
    Format: application/pdf
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  • 7
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    Nickel-Hydrogen Battery Cell Life Test Program Update for the International Space Station (2000)
    In:  CASI
    Details
    Publication Date: 2018-06-02
    Description: NASA and Boeing North America are responsible for constructing the electrical power system for the International Space Station (ISS), which circles the Earth every 90 minutes in a low Earth orbit (LEO). For approximately 55 minutes of this orbit, the ISS is in sunlight, and for the remaining 35 minutes, the ISS is in the Earth s shadow (eclipse). The electrical power system must not only provide power during the sunlight portion by means of the solar arrays, but also store energy for use during the eclipse. Nickel-hydrogen (Ni/H2) battery cells were selected as the energy storage systems for ISS. Each battery Orbital Replacement Unit (ORU) comprises 38 individual series-connected Ni/H2 battery cells, and there are 48 battery ORU s on the ISS. On the basis of a limited Ni/H2 LEO data base on life and performance characteristics, the NASA Glenn Research Center at Lewis Field commenced testing through two test programs: one in-house and one at the Naval Surface Warfare Center in Crane, Indiana.
    Keywords: Energy Production and Conversion
    Type: Research and Technology 1999; NASA/TM-2000-209639
    Format: application/pdf
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  • 8
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    The instrument on NASA's GRACE Mission: Augmentation of GPS to achieve unprecedented gravity field measurements (2002)
    In:  Other Sources
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    Publication Date: 2018-06-08
    Type: 15th Technical Meeting of the Satellite Division of the Institute of Navigation; Portland, OR; United States
    Format: text
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  • 9
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    The Influence of Surface Morphology and Diffraction Resolution of Canavalin Crystals (2003)
    In:  Other Sources
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    Publication Date: 2019-07-18
    Description: Canavalin crystals grown from material purified and not purified by High Performance Liquid Chromatography were studied by atomic force microscopy and x-ray diffraction. After purification, resolution was improved from 2.55Angstroms to 2.22Angstroms and jagged isotropic spiral steps transformed into regular, well polygonized steps.
    Keywords: Solid-State Physics
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  • 10
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    Composition of Rheasilvia Basin on Asteroid Vesta (2014)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: The focus of the present study is the compositional analysis of small-scale surface features within the Rheasil-Aa basin on asteroid Vesta. We are using data acquired by the Visible and InfraRed mapping Spectrometer (VIR) on the Dawn mission. Nominal spatial resolution of the data set considered in this study is 70m/px. The portion of Rheasil-Aa basin below 65degS has a howarditic composition, with the higher concentration of diogenitic versus eucritic material in the region between 45deg and 225degE-lon. However, there are several locations, such as craters Tarpeia and Severina and Parentatio Rupes, with lithologic characteristics different from the surroundings regions. Tarpeia crater has a eucritic patch in the west side of the crater, the bottom part ofthe wall and part of the floor. Severina, located in a region of Mg-rich pyroxene, has some diogenitic units on the walls of the crater. Also the Parentatio Rupes has an ob-AOUS diogenitic unit. These units extend for 10-20km, and their location, especially in the case of the two craters, suggests they formed before the cratering events and also before the Rheasil-Aa impact event. The origin of these units is still unclear; however, their characteristics and locations suggests heterogeneity in the composition of the ancient Vestan crust in this particular location of the surface.
    Keywords: Lunar and Planetary Science and Exploration
    Type: JSC-CN-32077 , American Geophysical Union (AGU) Fall Meeting; Dec 15, 2014 - Dec 19, 2014; San Francisco, CA; United States
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