Journal of Applied Crystallography turns forty

Editorial.

High-resolution synchrotron radiation studies on natural and thermally annealed scleractinian coral biominerals

The structural phase transition from aragonite to calcite in biogenic samples extracted en bloc (without pulverization) from the skeletons of two scleractinian corals (Desmophyllum and Favia) was studied by synchrotron radiation diffraction.

New solutions to the problems of chain orientation and chain continuity in structure analysis of fibrous polymers. A reconsideration of the structure of polyisobutene

Chain orientation and chain continuity in structural refinement of polymers are discussed. The structure of polyisobutene has been reconsidered, using new X-ray diffraction measurements and performing a structure refinement with the aid of a proprietary computer program, based on revised approaches to the presented arguments.

Simulation of small-angle scattering curves by numerical Fourier transformation

A simple numerical approach for calculating the q-dependence of the scattering intensity in small-angle X-ray or neutron scattering (SAXS/SANS) is discussed.

Effective hydrostatic limits of pressure media for high-pressure crystallographic studies

Stress-induced broadening of single-crystal reflections together with the measurement of shear wave propagation has been used to determine the effective limits of hydrostatic behaviour in several fluids widely used as pressure media.

Microstructural characterization of ball-milled α-Al₂O₃: bimodal size distribution and shape anisotropy

Microstructural characterization of ball-milled α-Al₂O₃ has been performed by X-ray line broadening analysis. The super-Lorentzian profile shapes of the X-ray diffraction pattern have been characterized by bimodal size distribution and shape anisotropy of the milled α-Al₂O₃ crystallites.

Resolution functions of time-of-flight small-angle neutron scattering instruments with rectangular apertures

Analytic expressions are developed for the resolution functions of small-angle neutron scattering instruments. Applications, including the optimal design, the analyses of smearing effects as well as data re-binning, to the case of time-of-flight devices with rectangular apertures are presented.

Superstructure phase in the binary C₂₈H₅₈:C₃₆H/D₇₄ system

A new solid-solution phase has been identified in the binary paraffin blend xC₂₈H₅₈.(1−x)C₃₆H/D₇₄ for 0.94 ≥ x ≥ 0.65.

Contrast variation in small-angle scattering experiments on polydisperse and superparamagnetic systems: basic functions approach

The method of basic functions in the contrast variation technique of small-angle scattering is considered for cases of polydisperse and superparamagnetic systems.

Structure model and small-angle scattering cross sections of latent ion tracks in dielectric solids

Theoretical small-angle X-ray scattering cross sections of modeled latent ion tracks have been derived, enabling the determination of structure parameters of tracks created along wakes of highly energetic heavy ions in dielectric solids.

A strategy for rapid analysis of the variations in the reduced distribution function of liquid metals and metallic glasses

Structural analysis of metallic liquids and glasses is complicated by the lack of long-range order.

Parametric Rietveld refinement

The use of `parametric Rietveld refinement' to extract information from large numbers of powder diffraction patterns using a single evolving structural model is described.

Determination of the morphological texture of the fibres in a composite material made from a textile of AISI 316L fibres using a mixed deconvolution/positivity method

The orientation distribution or `morphological texture function' of the fibres in a composite material is determined from measurements of the crystallographic texture of the fibres themselves.

Crystal structure prediction of organic pigments: quinacridone as an example

The structures of the α, β and γ polymorphs of quinacridone were predicted using Polymorph Predictor software in combination with X-ray powder diffraction patterns of limited quality. The present work demonstrates a method to obtain crystal structures of industrially important pigments when only a low-quality powder pattern is available.

Scanning texture analysis of lamellar bone using microbeam synchrotron X-ray radiation

Microbeam scanning texture analysis enables the determination of the orientations of the mineral apatite nanocrystals in bone with a positional resolution of 1 µm.

Successful protein cryocooling for powder diffraction

The possibility of performing powder diffraction experiments on proteins under cryocooled conditions has been demonstrated by means of systematic variations of the concentration and type of cryoprotectant agent on chicken egg white lysozyme.

Thermal properties of monoclinic crystal Er³⁺:Yb³⁺:Ca₄YO(BO₃)₃

The crystal symmetry and quality of an Er³⁺–Yb³⁺ co-doped yttrium calcium oxoborate [Er³⁺:Yb³⁺:Ca₄YO(BO₃)₃, abbreviated as Er:Yb:YCOB] crystal, grown by the Czochralski method, were examined using X-ray diffraction. The specific heat, thermal expansion coefficient and thermal conductivity of the as-grown Er:Yb:YCOB crystal were studied systematically using crystal samples with different crystallographic orientations.

Multipattern Rietveld refinement of protein powder data: an approach to higher resolution

Use of 2 Å multiple protein image-plate powder patterns that show solvent-induced or radiation-damage-induced lattice strains gives improved structural results from stereochemically restrained Rietveld refinements.

A simple model for dynamic small-angle X-ray diffraction in colloidal crystals

Dynamic (multiple) diffraction effects were recently shown to play a role in the diffraction of colloidal crystals. A simple model is presented based on the Wentzel–Kramer–Brillouin approximation to allow for dynamic effects.

Phase-object approximation in small-angle neutron scattering experiments on silicon gratings

A method based on the phase-object approximation is used to describe small-angle neutron scattering experiments on silicon gratings.

Structural investigation of the photoinduced spin conversion in the dinuclear compound {[Fe(bt)(NCS)₂]₂(bpym)}: toward controlled multi-stepped molecular switches

Photocrystallography is used to investigate the photoswitching of the compound {[Fe(bt)(NCS)₂]₂(bpym)}, by combining X-ray diffraction and laser irradiation. The structural investigations demonstrate the strong coupling between the electronic and structural degrees of freedom and the photoselective and reversible switching between different states.

Improvement of data treatment in small-angle neutron scattering

General equations are given for background subtraction of SANS treatment, which account for large scattering angles () and allow the extraction of the scattering due to the sample when the later is inside a container that displays a spurious scattering signal. Several calibration methods to determine the inherent sample backgrounds are also described.

The CCP13 FibreFix program suite: semi-automated analysis of diffraction patterns from non-crystalline materials

FibreFix integrates various programs for the analysis of non-crystalline diffraction patterns into a single user-friendly package. The main features of FibreFix are outlined and some of its applications are illustrated.

Fortran90 sources of the subroutines of UMWEG. III. The UMWEG-specific subroutines

The Fortran90 sources of the UMWEG-specific subroutines of the program UMWEG are presented and deposited, together with the PostScript-plot software subroutines and the simple and short main program of the command-line version of the program UMWEG.

DRAWxtl, an open-source computer program to produce crystal structure drawings

DRAWxtl is an open-source computer program for crystal structure drawings that can be used with the Windows, Mac OS X and Linux operating systems. Beginning with version 5.3, the program can display aperiodic structures in up to (3+3) dimensions.

Focusing capillary optics for use in solution small-angle X-ray scattering

The successful application of single-bounce X-ray focusing capillary small-angle X-ray scattering measurements on proteins, without loss of resolution, is presented.

Hydrostatic low-range pressure applications of the Paris–Edinburgh cell utilizing polymer gaskets for diffuse X-ray scattering measurements

The use of a polymeric (Torlon or polyamide–imide) gasket material in a Paris–Edinburgh pressure cell for in situ high-pressure X-ray scattering measurements is demonstrated. The quality of the data obtained in this way is suitable for Bragg and pair distribution function analysis.

An apparatus for electric-field-induced protein crystallization

A new device for electric-field-induced protein crystallization using the microbatch method has been fabricated and successfully tested.

DHS1100: a new high-temperature attachment for materials science in the whole orientation space

Notes for authors 2007

Forthcoming meetings and short courses