scholarly journals The Use of Connected Masks for Reconstructing the Single Particle Image from X-Ray Diffraction Data. III. Maximum-Likelihood Based Strategies to Select Solution of the Phase Problem

Author(s):  
N.L. Lunina ◽  
T.E. Petrova ◽  
A.G. Urzhumtsev ◽  
V.Y. Lunin
Author(s):  
Н.Л. Лунина ◽  
N.L. Lunina

Advances in the methodology of the X-ray diffraction experiments leads to a possibility to register the rays scattered by large isolated biological particles (viruses and individual cells) but not only by crystalline samples. The experiment with an isolated particle provides researchers with the intensities of the scattered rays for the continuous spectrum of scattering vectors. Such experiment gives much more experimental data than an experiment with a crystalline sample where the information is limited to a set of Bragg reflections. This opens up additional opportunities in solving underlying problem of X-ray crystallography, namely, calculating phase values for the scattered waves needed to restore the structure of the object under study. In practice, the original continuous diffraction pattern is sampled, reduced to the values at grid points in the space of scattering vectors (in the reciprocal space). The sampling step determines the amount of the information involved in solving the phase problem and the complexity of the necessary calculations. In this paper, we investigate the effect of the sampling step on the accuracy of the phase problem solution obtained by the method proposed earlier by the authors. It is shown that an expected improvement of the accuracy of the solution with the reducing the sampling step continues even after crossing the Nyquist limit defined as the inverse of the double size of the object under study.


1995 ◽  
Vol 73 (5-6) ◽  
pp. 209-218 ◽  
Author(s):  
J. Katsaras

This brief review of the X-ray diffraction technique used to study oriented lipid bilayer systems is primarily intended to demonstrate to the nonspecialist in the lipid field the amount of detailed information that can be obtained simply by visually inspecting the diffraction pattern and making some measurements with a ruler and protractor. The information that can be extracted from X-ray diffraction data is illustrated by selected examples of our most recent work.Key words: X-ray diffraction, oriented multibilayers, electron density profiles, subgel phase, phase problem.


1999 ◽  
Vol 55 (9) ◽  
pp. 1618-1619 ◽  
Author(s):  
A. L. S. Smarra ◽  
V. Fadel ◽  
M. Dellamano ◽  
J. R. Olivieri ◽  
W. F. de Azevedo ◽  
...  

Oxyhaemoglobin I isolated from the Brazilian wolf Chrysocyon brachiurus has been crystallized and X-ray diffraction data has been collected to 2.06 Å resolution using a synchrotron-radiation source. Crystals were determined to belong to the space group P212121 and preliminary structural analysis revealed the presence of one tetramer in the asymmetric unit. The structure was determined using standard molecular-replacement techniques and is currently being refined using maximum-likelihood protocols. This is the first haemoglobin isolated from a member of the Canidae family to be crystallized and it will provide further insights in the comparative biochemistry of vertebrate haemoglobins.


2014 ◽  
Vol 22 (3) ◽  
pp. 2497 ◽  
Author(s):  
Jakob Andreasson ◽  
Andrew V. Martin ◽  
Meng Liang ◽  
Nicusor Timneanu ◽  
Andrew Aquila ◽  
...  

2019 ◽  
Vol 74 (4) ◽  
pp. 357-363
Author(s):  
Daniela Vitzthum ◽  
Hubert Huppertz

AbstractThe mixed cation triel borate Ga4In4B15O33(OH)3 was synthesized in a Walker-type multianvil apparatus at high-pressure/high-temperature conditions of 12.5 GPa and 1300°C. Although the product could not be reproduced in further experiments, its crystal structure could be reliably determined via single-crystal X-ray diffraction data. Ga4In4B15O33(OH)3 crystallizes in the tetragonal space group I41/a (origin choice 2) with the lattice parameters a = 11.382(2), c = 15.244(2) Å, and V = 1974.9(4) Å3. The structure of the quaternary triel borate consists of a complex network of BO4 tetrahedra, edge-sharing InO6 octahedra in dinuclear units, and very dense edge-sharing GaO6 octahedra in tetranuclear units.


1984 ◽  
Vol 140 (2-3) ◽  
pp. 202-205 ◽  
Author(s):  
Walter Morisset ◽  
Werner Wehrmeyer ◽  
Tilman Schirmer ◽  
Wolfram Bode

2021 ◽  
Author(s):  
Anna Agnieszka Hoser ◽  
Marcin Sztylko ◽  
Damian Trzybiński ◽  
Anders Østergaard Madsen

A framework for estimation of thermodynamic properties for molecular crystals via refinement of frequencies from DFT calculations against X-ray diffraction data is presented. The framework provides an efficient approach to...


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