issue contents

ISSN: 2053-2733

May 2018 issue

Highlighted illustration

Cover illustration: A new mathematical model of a light source enables faster, brighter and sharper X-ray imaging by ptychography [Chang et al. (2018). Acta Cryst. A74, 157-169]. The image shows the illuminating beam from a light source and its gradient decomposition, superimposed on images of gold nanospheres before and after partial coherence analysis.


research papers

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Partially coherent effects in ptychography are addressed by using a simple and efficient model with only one coherent probe, its gradient and the variance of a convolution kernel.

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Errors on molecular properties including the topology of electron density and electrostatics are estimated from a sample of deviating models generated using the variance–covariance matrix issued at the end of the charge-density refinement.


research papers

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AFLOW-SYM is a comprehensive crystal-symmetry analysis suite catering to automated computational workflows and presenting a wealth of symmetry descriptions. This platform employs robust mapping techniques, validates calculated symmetry elements and resolves self-consistent tolerances for each system to yield results more commensurate with experiments compared with other common symmetry packages.

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The dependence of X-ray rocking curves on the deviation angle from the exact Bragg orientation in the diffraction plane and in the direction perpendicular to the diffraction plane is investigated for the asymmetrical Laue case.

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New parametric equations are developed for crystal orientation, the solutions of which are free of constraints or approximations and are well suited for determination of crystal orientation with high accuracy and precision. These equations are validated and checked for orienting of single crystals with high precision and accuracy.

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Using a simple invariant representation scheme for graphs, a number of reticular networks are identified as surface embeddings of the famous Klein and Möbius–Kantor graphs on periodic surfaces.

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A quantitative theory of Fraunhofer diffraction by a cylindrical scroll nanotube based on the kinematical approach is presented. The reciprocal lattice of a cylindrical scroll nanotube and its relation to the nanotube lattice parameters are determined on the basis of the proposed theory.

international union of crystallography


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