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PubMed Central (PMC3 - NLM DTD) (3.020.751 recursos)

Archive of life sciences journal literature at the U.S. National Institutes of Health (NIH), developed and managed by NIH's National Center for Biotechnology Information (NCBI) in the National Library of Medicine (NLM).

Acta Crystallographica Section A: Foundations of Crystallography

Mostrando recursos 1 - 15 de 15

  1. Structural constraints on the three-dimensional geometry of simple viruses: case studies of a new predictive tool

    Keef, Thomas; Wardman, Jessica P.; Ranson, Neil A.; Stockley, Peter G.; Twarock, Reidun
    A new concept in virology provides insights into structural constraints on virus structure, extending Caspar–Klug theory to include predictions across all radial levels of the virus particle including genome organization. The predictive power of the new tool is demonstrated for a range of viruses, revealing a previously unrecognized structural interdependence of shapes and sizes of different viral components.

  2. High-resolution study of (002, 113, 11−1) four-beam diffraction in Si

    Kohn, V. G.; Kazimirov, A.
    A high-resolution study of (002, 113, 11−1) four-beam diffraction in Si was performed both experimentally and theoretically. Excellent coincidence between theory and experiment was achieved. The forbidden two-beam 002 reflection was excited with the maximum reflectivity of 80%.

  3. Some B eq are more equivalent than others

    Merritt, Ethan A.
    B eq is a well defined entity that represents one property, mean-square displacement, of the anisotropic atomic displacement parameter tensor from which it is derived. B eq is not, however, the best estimate of the B factor that would result from isotropic model refinement. A new entity B est is proposed to serve this purpose.

  4. Mathematical aspects of molecular replacement. I. Algebraic properties of motion spaces

    Chirikjian, Gregory S.
    Search spaces in the method of molecular replacement are shown to be coset spaces of the Lie group of rigid-body motions by the chiral space group of a crystal. The resulting ‘motion space’ can be endowed with a quasigroup operation that has interesting properties which are explored here.

  5. High-resolution study of (222, 113) three-beam diffraction in Ge

    Kazimirov, A.; Kohn, V. G.
    Good agreement between the high-resolution experimental results for (222, 113) three-beam diffraction in Ge and computer simulations based on the dynamical multiple diffraction theory are presented.

  6. The development of Laue techniques for single-pulse diffraction of chemical complexes: time-resolved Laue diffraction on a binuclear rhodium metal-organic complex

    Makal, Anna; Trzop, Elzbieta; Sokolow, Jesse; Kalinowski, Jaroslaw; Benedict, Jason; Coppens, Philip
    A modified Laue technique suitable for time-resolved diffraction is described in which profile-independent integration is used, the RATIO method is applied and multi-crystal data are normalized to a common scale. The method is applied in single-pulse pump–probe studies of a binuclear Rh complex, showing Rh—Rh bond shortening of 0.136 (8) Å on excitation.

  7. Structure-factor analysis of femtosecond microdiffraction patterns from protein nanocrystals

    Kirian, Richard A.; White, Thomas A.; Holton, James M.; Chapman, Henry N.; Fromme, Petra; Barty, Anton; Lomb, Lukas; Aquila, Andrew; Maia, Filipe R. N. C.; Martin, Andrew V.; Fromme, Raimund; Wang, Xiaoyu; Hunter, Mark S.; Schmidt, Kevin E.; Spence, John C. H.
    A complete set of structure factors has been extracted from hundreds of thousands of femtosecond X-ray diffraction patterns from randomly oriented Photosystem I membrane protein nanocrystals, using the Monte Carlo method of intensity integration. The data, collected at the Linac Coherent Light Source, are compared with conventional single-crystal data collected at a synchrotron source, and the quality of each data set was found to be similar.

  8. Exact direct-space asymmetric units for the 230 crystallographic space groups

    Grosse-Kunstleve, Ralf W.; Wong, Buddy; Mustyakimov, Marat; Adams, Paul D.
    A reference table of exact direct-space asymmetric units for the 230 crystallographic space groups is presented, based on a new geometric notation for asymmetric unit conditions.

  9. Translation calibration of inverse-kappa goniometers in macromolecular crystallography

    Brockhauser, Sandor; White, Kristopher I.; McCarthy, Andrew A.; Ravelli, Raimond B. G.
    A rapid, easy-to-perform translation calibration procedure has been developed for use with the EMBL/ESRF mini-κ goniometer head and for other inverse-kappa goniometers designed for macromolecular crystallography. Regular calibration ensures the precision of experiments that rely on many degrees of freedom in crystal reorientation.

  10. Geometric properties of nucleic acids with potential for autobuilding

    Gruene, Tim; Sheldrick, George M.
    Algorithms and geometrical properties are described for the automated building of nucleic acids in experimental electron density.

  11. High-resolution study of dynamical diffraction phenomena accompanying the Renninger (222/113) case of three-beam diffraction in silicon

    Kazimirov, A.; Kohn, V. G.
    The effect of the total reflection of the incident beam into the 222 reflected beam in the Renninger (222/113) case in Si was experimentally observed by using a highly monochromatic beam with high angular collimation in both the vertical and horizontal planes.

  12. Time-resolved structural studies of protein reaction dynamics: a smorgasbord of X-ray approaches

    Westenhoff, Sebastian; Nazarenko, Elena; Malmerberg, Erik; Davidsson, Jan; Katona, Gergely; Neutze, Richard
    Time-resolved structural studies of proteins have undergone several significant developments during the last decade. Recent developments using time-resolved X-ray methods, such as time-resolved Laue diffraction, low-temperature intermediate trapping, time-resolved wide-angle X-ray scattering and time-resolved X-ray absorption spectroscopy, are reviewed.

  13. Five-dimensional crystallography

    Schmidt, Marius; Graber, Tim; Henning, Robert; Srajer, Vukica
    Here it is demonstrated how five-dimensional crystallography can be used to determine a comprehensive chemical kinetic mechanism in concert with the atomic structures of transient intermediates that form and decay during the course of the reaction.

  14. Time-resolved synchrotron diffraction and theoretical studies of very short-lived photo-induced molecular species

    Coppens, Philip; Benedict, Jason; Messerschmidt, Marc; Novozhilova, Irina; Graber, Tim; Chen, Yu-Sheng; Vorontsov, Ivan; Scheins, Stephan; Zheng, Shao-Liang
    Excited-state geometries determined by time-resolved synchrotron diffraction are summarized with emphasis on their comparison with a series of theoretical results. The relative merits of monochromatic and polychromatic (Laue) techniques are discussed.

  15. Depth profiling of polymer films with grazing-incidence small-angle X-ray scattering

    Singh, Marsha A.; Groves, Michael N.
    A procedure for obtaining depth-specific scattering profiles of laterally defined nanostructure using grazing-incidence small-angle X-ray scattering is described.

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