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  • 1
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    X-Ray Diffraction and Imaging Study of Imperfections of Crystallized Lysozyme with Coherent X-Rays (2003)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Phase-sensitive x-ray diffraction imaging and high angular-resolution diffraction combined with phase contrast radiographic imaging are employed to characterize defects and perfection of a uniformly grown tetragonal lysozyme crystal in symmetric Laue case. The fill width at half-maximum (FWHM) of a 4 4 0 rocking curve measured from the original crystal is approximately 16.7 arcseconds, and defects, which include point defects, line defects, and microscopic domains, have been clearly observed in the diffraction images of the crystal. The observed line defects carry distinct dislocation features running approximately along the 〈110〉 growth front, and they have been found to originate mostly at a central growth area and occasionally at outer growth regions. Individual point defects trapped at a crystal nucleus are resolved in the images of high sensitivity to defects. Slow dehydration has led to the broadening of the 4 4 0 rocking curve by a factor of approximately 2.4. A significant change of the defect structure and configuration with drying has been revealed, which suggests the dehydration induced migration and evolution of dislocations and lattice rearrangements to reduce overall strain energy. The sufficient details of the observed defects shed light upon perfection, nucleation and growth, and properties of protein crystals.
    Keywords: Nonmetallic Materials
    Format: text
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    NASA TECHNICAL REPORTS
  • 2
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    Surface Relaxation in Protein Crystals (2002)
    In:  Other Sources
    Details
    Publication Date: 2019-07-18
    Description: Surface X-ray diffraction measurements were performed on (111) growth faces of crystals of the Cellular iron-storage protein horse spleen ferritin. Crystal Trunkation Rods (CTR) were measured. A fit of the measured profile of the CTR revealed a surface roughness of 48 +/- 4.5 A and a top layer spacing contraction of 3.9 +/- 1.5%. In addition to the peak from the CTR, the rocking curves of the crystals displayed unexpected extra peaks. Multiple-scattering is demonstrated to account for them. Future applications of the method could allow the exploration of hydration effects on the growth of protein crystals.
    Keywords: Nonmetallic Materials
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    NASA TECHNICAL REPORTS
  • 3
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    Overview of the Icing and Flow Quality Improvements Program for the NASA Glenn Icing Research Tunnel (2001)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Major upgrades were made in 1999 to the 6- by 9-Foot (1.8- by 2.7-m) Icing Research Tunnel (IRT) at the NASA Glenn Research Center. These included replacement of the electronic controls for the variable-speed drive motor, replacement of the heat exchanger, complete replacement and enlargement of the leg of the tunnel containing the new heat-exchanger, the addition of flow-expanding and flow-contracting turning vanes upstream and downstream of the heat exchanger, respectively, and the addition of fan outlet guide vanes (OGV's). This paper describes the rationale behind this latest program of IRT upgrades and the program's requirements and goals. An overview is given of the scope of work undertaken by the design and construction contractors, the scale-model IRT (SMIRT) design verification program, the comprehensive reactivation test program initiated upon completion of construction, and the overall management approach followed.
    Keywords: Research and Support Facilities (Air)
    Type: NASA/TM-2001-210686 , NAS 1.15:210686 , E-12613 , AIAA Paper 2001-0229 , 39th Aerospace Sciences Meeting and Exhibit; Jan 08, 2001 - Jan 11, 2001; Reno, NV; United States
    Format: application/pdf
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    NASA TECHNICAL REPORTS
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