issue contents

Journal logoJOURNAL OF
ISSN: 1600-5767

April 1997 issue

Highlighted illustration

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.

research papers

J. Appl. Cryst. (1997). 30, 87-91
doi: 10.1107/S0021889896010199
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It has been found that the two positive glitches observed at 1385.6 and 1438 eV in the transmission function of the YB66 double-crystal monochromator are caused by the anomalous increases of the reflective intensity of the 006 reflection at the yttrium LIII and LII absorption edges. The intensities of these two glitches are reduced to minimal values by the installation of an SiC cut-off mirror downstream from the YB66 monochromator.

J. Appl. Cryst. (1997). 30, 92-97
doi: 10.1107/S0021889896010382
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A probabilistic method is integrated with the Le Bail algorithm to decompose a powder diffraction pattern: it provides more accurate estimates of the structure-factor amplitudes.

J. Appl. Cryst. (1997). 30, 98-101
doi: 10.1107/S0021889896010448
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In this paper, higher-order Laue Zone (HOLZ) lines in BaTiO3 ceramics are obtained and a tiny difference of the lattice parameters between the pure and Ba(Ti,Sn)O3 ceramics has been observed in nanometre-sized areas.

J. Appl. Cryst. (1997). 30, 102-106
doi: 10.1107/S002188989601045X
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The theoretical function describing the probability density of disorientation axes is obtained for cubic polycrystals. An analytical expression for this density function is determined in spherical coordinates to facilitate graphical representation.

J. Appl. Cryst. (1997). 30, 107-113
doi: 10.1107/S0021889896010503
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The application of the Rietveld method to different X-ray powder diffraction spectra allows the determination of the mass fraction evolution and the mean size evolution with aging time at 453 K of the δ' precipitates in an Al–Li alloy.

J. Appl. Cryst. (1997). 30, 114-117
doi: 10.1107/S0021889896010916
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The microstructure of three-component Fibonacci Ta/Al multilayer films is studied by transmission electron microscopy and electron and X-ray diffraction.

J. Appl. Cryst. (1997). 30, 118-122
doi: 10.1107/S0021889896012228
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The packing coefficient in orientational disordered phases for a set of series of compounds derived from neopentane and their molecular alloys is reported in order to analyze the molecular interactions.

J. Appl. Cryst. (1997). 30, 123-127
doi: 10.1107/S0021889896012460
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The results of the structural determination of Li2MnO3 from X-ray powder diffraction data and refinement by the Rietveld technique are presented.

J. Appl. Cryst. (1997). 30, 128-132
doi: 10.1107/S0021889896012733
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A numerical method for evaluation of the performance of a new peak-integration procedure is presented.

J. Appl. Cryst. (1997). 30, 133-137
doi: 10.1107/S0021889896012824
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Various peak integration procedures are compared with an idealized least-squares procedure, and it is shown that, in practical conditions, an analytic σ(I)/I procedure comes very close to the ideal.

J. Appl. Cryst. (1997). 30, 138-146
doi: 10.1107/S002188989600893X
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A neutron beam, reflected by a thin-film multilayer monochromator, will also contain the long-wavelength component of the incident spectrum in addition to the desired band of wavelengths. A number of approaches have been suggested to minimize this contamination.

J. Appl. Cryst. (1997). 30, 147-152
doi: 10.1107/S0021889896010023
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Line-profile simulation and matching on the basis of a paracrystalline one-dimensional Hosemann's model provides a promising approach to the analysis of X-ray line broadening and is presented here.

J. Appl. Cryst. (1997). 30, 153-163
doi: 10.1107/S0021889896010862
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An accurate structural model of native cutinase was derived from Laue data recorded in 8.5 ns at the European Synchrotron Radiation Facility, demonstrating the potential of very rapid Laue data collection for time-resolved studies.

J. Appl. Cryst. (1997). 30, 164-170
doi: 10.1107/S0021889896011442
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The polarization state of the transmitted beam in Bragg-case X-ray diffraction has been determined.

computer programs

J. Appl. Cryst. (1997). 30, 171-175
doi: 10.1107/S002188989600934X
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The program DISCUS is a versatile tool for the analysis of diffuse scattering and for defect-structure simulations.

J. Appl. Cryst. (1997). 30, 176-177
doi: 10.1107/S0021889896013210
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Features of a new program for single-isomorphous-replacement and single-wavelength-anomalous-scattering local scaling are described.

J. Appl. Cryst. (1997). 30, 178-181
doi: 10.1107/S0021889896013453

laboratory notes

J. Appl. Cryst. (1997). 30, 182-183
doi: 10.1107/S0021889896010527
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A perspex box for crystal growth by vapour diffusion has been designed.

fast communications

J. Appl. Cryst. (1997). 30, 184-189
doi: 10.1107/S0021889896010886
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The structure of an organic material, acetylcholine bromide, is refined from neutron diffraction data deliberately collected from a multiple-crystal sample. The method developed has clear promise in several areas including allowing more rapid data collections, enabling the use of smaller crystals and studying single-crystal samples in more complex sample environments.

J. Appl. Cryst. (1997). 30, 190-194
doi: 10.1107/S0021889896012939
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A method for preparing cryocooled xenon-derivatized protein crystals is presented.

J. Appl. Cryst. (1997). 30, 195-197
doi: 10.1107/S0021889896013404
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It is shown how neutron reflectivity is altered when magnetic field gradients are present along the neutron path.

J. Appl. Cryst. (1997). 30, 198-202
doi: 10.1107/S0021889896013532
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A simple technique for improving the size of protein crystals by controlling the rate of vapour-diffusion trials is presented.

J. Appl. Cryst. (1997). 30, 203-205
doi: 10.1107/S0021889897003907
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By comparison of the accuracy and the merging R factor (Rmerge) of artificially created X-ray data sets, it is demonstrated that Rmerge is a poor predictor for the precision of X-ray data. The more often a given reflection is observed, the more precise the average intensity is, whereas Rmerge has a tendency to be higher at higher data redundancy.

computer program abstracts

J. Appl. Cryst. (1997). 30, 206
doi: 10.1107/S0021889896015129
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A program for the manual indexation of area-detector data is presented.

J. Appl. Cryst. (1997). 30, 206-207
doi: 10.1107/S0021889896014008
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A program that, given the tilt system, tilt angles and octahedral bond distances, will calculate the ideal crystal structure for AMO3 and A2MM'O6 perovskites distorted by octahedral tilting is presented.

See the Journal of Applied Crystallography Software List 1997.

J. Appl. Cryst. (1997). 30, 207-208
doi: 10.1107/S0021889896013441
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DEBVIN is a program that combines the Rietveld approach with the use of generalized coordinates. It is a particularly useful tool when, as in polymer crystallography, structures are rather complex and diffraction patterns highly overlapped and confined to low diffraction angles. Refinement of crystallite dimensions is also a qualifying feature of this program.

See the Journal of Applied Crystallography Software List 1997.


J. Appl. Cryst. (1997). 30, 208-209
doi: 10.1107/S0021889897099093

notes and news

J. Appl. Cryst. (1997). 30, 209
doi: 10.1107/S0021889897099081

international union of crystallography

J. Appl. Cryst. (1997). 30, 209
doi: 10.1107/S002188989709907X

new commercial products

J. Appl. Cryst. (1997). 30, 209
doi: 10.1107/S0021889897099068

books received

J. Appl. Cryst. (1997). 30, 209
doi: 10.1107/S0021889897099056

J. Appl. Cryst. (1997). 30, 209
doi: 10.1107/S0021889897099044

J. Appl. Cryst. (1997). 30, 209
doi: 10.1107/S0021889897099032

J. Appl. Cryst. (1997). 30, 209
doi: 10.1107/S0021889897099020
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