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February 1997 issue
Cover illustration: A crystal of the protein phosphorylase b flash-cooled to 100 K in a 1 mm-diameter mohair loop prior to collection of X-ray diffraction data. Courtesy of Elspeth Garman and Stephen Lee, University of Oxford.
international union of crystallography
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research papers
The theory and design principles of the monolithic double-crystal spectrometer are presented.
The technique of high-energy monochromatic Laue X-ray scattering using image plates to record the diffraction patterns is presented.
Synchrotron X-ray powder diffraction using the imaging-plate technique makes it possible to obtain structural information using short exposure times. As examples are given the refinement of the structure of α-quartz and the structure determination of a new zirconium hydrogen phosphate, Zr(HPO4)2. Equations for data reduction for flat imaging-plate geometry are presented.
By an iterative combination of the crystallographic Rietveld method and discrete methods of texture analysis, quantitative information about texture can be obtained from diffraction spectra. The new method relies on spectra from a few sample orientations and many diffraction peaks.
The orientation distribution of two low-crystal-symmetry phases, YBCO 123 and 211, in a magnetically aligned high-critical-temperature superconducting sample, has been determined with the WIMV algorithm from highly incomplete pole figures, measured by neutron diffraction.
An evacuated temperature-controlled cell has been built for small-angle X-ray scattering measurements with synchrotron radiation. The use of this cell results in a reduction of the background by a factor of between 2 and 15 as a function of the scattering angle.
Structural parameters of a kaolinite-type clay mineral are determined by the use of R factors. The model used contains ±b/3 translational defects.
A simple method for the determination of deuterium incorporation into nonexchangeable (C-bonded) positions of RNA and protein components of the Escherichia coli ribosome at biosynthetic deuteration using small-angle neutron scattering is proposed.
The φ extent of the reflection range in the oscillation method has been analyzed according to the mosaicity-cap model using a nest of Ewald spheres. The formulas are used in the software for processing area-detector data.
cryocrystallography papers
A practical step-by-step description of the construction of loops for protein cryocrystallography using pulled-out microinjection capillaries is presented.
computer programs
The program SPGR4D is written in Fortran77 for deriving four-dimensional symmetry operations from the corresponding space-group symbols.
See the Journal of Applied Crystallography Software List 1997.
CIF applications
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A software library is described that provides simple and convenient access to information in Crystallographic Information File (CIF) dictionaries and data files.
See the Journal of Applied CrystallographySoftware List 1997.
computer program abstracts
A program for the refinement of unit-cell parameters is described. It incorporates deletion diagnostics, enabling the identification of erroneous measurements and outliers in the data set.
See the Journal of Applied Crystallography Software List 1997
An interactive freeware DOS program for plotting and viewing Rietveld refinement data is presented.
See the Journal of Applied Crystallography Software List 1997.
An interactive PC-DOS program for displaying crystal structures is presented.
See the Journal of Applied Crystallography Software List 1997.
An interactive PC-DOS program for simulating Kossel and Kikuchi patterns for crystals and quasicrystals is presented.
See the Journal of Applied Crystallography Software List 1997.
crystallographers
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