Journal of Applied Crystallography

 

J. Appl. Cryst. (2006). 39, 293-303  [ doi:10.1107/S0021889806005255 ]

Method of separated form factors for polydisperse vesicles

J. Pencer, S. Krueger, C. P. Adams and J. Katsaras

Synopsis: The Laplace transform approach is combined with the separated form factor (SFF) approximation to obtain expressions for form factors for polydisperse spherical vesicles with various forms of membrane scattering length density profile. The SFF approximation is tested against exact form factors that have been numerically integrated over the size distribution, and is shown to represent the vesicle form factor accurately for typical vesicle sizes and membrane thicknesses.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 304-314  [ doi:10.1107/S0021889806005693 ]

Calculation of the instrumental function in X-ray powder diffraction

A. D. Zuev

Synopsis: A new method for calculating the instrumental function in powder diffraction is described.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 315-319  [ doi:10.1107/S0021889806005589 ]

Simple procedure for conformation-family search in multidimensional torsion-angle space

F. Pavelcik and J. Vanco

Synopsis: A method for studying conformation spaces in n dimensions has been developed. The method is used to calculate preferences of conformation families for the purpose of model building.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 320-325  [ doi:10.1107/S0021889806006662 ]

Measurement of stress/strain in single-crystal samples using diffraction

H. Yan and I. C. Noyan

Synopsis: The diffraction profiles from bent Si-single-crystal strips measured in the symmetric Bragg geometry with slits or CCD-based optics contain secondary `mirage' peaks in addition to the primary 004 reflections. These dynamical diffraction artefacts cause errors in strains calculated from the angular positions of the 004 peaks; possible ways to eliminate/minimize such errors are discussed.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 326-337  [ doi:10.1107/S0021889806007758 ]

Three-dimensional birefringence imaging with a microscope tilting-stage. I. Uniaxial crystals

L. A. Pajdzik and A. M. Glazer

Synopsis: The development of a microscope tilting-stage suitable for use with birefringence imaging is described, thus enabling precise three-dimensional birefringence information of uniaxial crystals to be obtained.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 338-346  [ doi:10.1107/S002188980600851X ]

The determination of pore volumes, pore shapes and diffusion paths in microporous crystals

H. Küppers, F. Liebau and A. L. Spek

Synopsis: The original option SOLV of the program PLATON, which is primarily devoted to the study of organic structures, has been extended to studies of microporous inorganic crystals.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 347-357  [ doi:10.1107/S0021889806009319 ]

The instrumental resolution function of synchrotron radiation powder diffractometers in the presence of focusing optics

F. Gozzo, L. De Caro, C. Giannini, A. Guagliardi, B. Schmitt and A. Prodi

Synopsis: A simple analytical expression that allows one to model the instrumental resolution function of synchrotron radiation powder diffractometers in the presence of focusing optics is formulated. Experimental evidence of the validity of the model is also provided.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 358-368  [ doi:10.1107/S0021889806009873 ]

A direct method for the determination of the mean orientation-dependent elastic strains and stresses in polycrystalline materials from strain pole figures

J. V. Bernier and M. P. Miller

Synopsis: A direct method is presented for obtaining the mean orientation-dependent elastic strains/stresses in polycrystalline materials from diffraction strain pole figures. Due to the inherent indeterminacy of this procedure, referred to as strain pole-figure inversion, a trial solution is chosen by satisfying a well-posed auxillary problem where conditional control is imposed to address the issues of robustness and physical relevance.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 369-375  [ doi:10.1107/S0021889806009903 ]

Geometrical parameterization of the crystal chemistry of P63/m apatite. II. Precision, accuracy and numerical stability of the crystal-chemical Rietveld refinement

P. H. J. Mercier, Y. Le Page, P. S. Whitfield and L. D. Mitchell

Synopsis: Crystal-chemical parameters of P6₃/m apatite extracted directly by least-squares refinement are nearly one order of magnitude more precise than those obtained through analysis of standard Rietveld refinement results and are more consistent with single-crystal results. The comparable numerical stability of both types of refinement is assessed by singular value decomposition of the least-squares matrix of normal equations.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 376-384  [ doi:10.1107/S002188980601082X ]

Microstructural analysis of integrated pin-shaped two-dimensional and three-dimensional ferroelectric capacitors from micro-focused synchrotron X-ray techniques

N. Menou, Ch. Muller, L. Goux, R. Barrett, J. G. Lisoni, M. Schwitters and D. J. Wouters

Synopsis: The microstructural characteristics of integrated pin-shaped two-dimensional and three-dimensional ferroelectric capacitors were analysed using an original approach combining micro-focused synchrotron X-ray fluorescence and diffraction. Various capacitor arrays were scanned with a step size of 0.2 µm while simultaneously acquiring fluorescence spectra and diffraction patterns in order to obtain, respectively, chemical and crystallographic mapping of the thin films constituting the capacitors.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 385-390  [ doi:10.1107/S0021889806010351 ]

Structural and microstructural characterization of bioapatites and synthetic hydroxyapatite using X-ray powder diffraction and Fourier transform infrared techniques

S. Chakraborty, S. Bag, S. Pal and A. K. Mukherjee

Synopsis: Four bioapatites of human-, goat- and rabbit-bone and human-teeth origin, and one synthetic hydroxyapatite prepared via microwave irradiation have been analyzed by powder XRD and FTIR techniques. The Rietveld analyses indicate partial replacement of phosphate ions by carbonate ions in all bioapatites.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 391-400  [ doi:10.1107/S0021889806011058 ]

Characterization of insulin microcrystals using powder diffraction and multivariate data analysis

M. Norrman, K. Ståhl, G. Schluckebier and S. Al-Karadaghi

Synopsis: X-ray powder diffraction has been used to characterize 12 microcrystalline formulations of insulin. Differences and similarities between the polymorphs could be visualized by principal-component analysis.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 401-409  [ doi:10.1107/S0021889806011526 ]

Symmetry properties and transformation behaviour of the X-ray stress factors

B. Ortner

Synopsis: The so-called X-ray elastic factors F_ij(, , hkl) are shown to have all the properties of a second-rank tensor. This leads to some conclusions that are helpful in the application of F.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 410-424  [ doi:10.1107/S0021889806012210 ]

A deconvolution method for the reconstruction of underlying profiles measured using large sampling volumes

Y.-S. Xiong and P. J. Withers

Synopsis: A deconvolution method for diffraction measurements based on a statistical learning technique is presented. The method allows predictions of both the convolution and the underlying function from noisy measurements, and in addition provides an estimation of the prediction uncertainty, i.e. error-bars.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 425-432  [ doi:10.1107/S0021889806012763 ]

Tracking reflections through cryogenic cooling with topography

J. J. Lovelace, C. R. Murphy, R. Pahl, K. Brister and G. E. O. Borgstahl

Synopsis: Topographs were collected for several reflections of a protein crystal at room and then cryo temperatures. At the cryogenic temperatures, a significantly increased mosaicity, with the overall original domain structure maintained but in a shattered state, is revealed along with increased background around the diffraction spots.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 433-442  [ doi:10.1107/S0021889806012337 ]

Grazing-incidence small-angle X-ray scattering from thin polymer films with lamellar structures - the scattering cross section in the distorted-wave Born approximation

P. Busch, M. Rauscher, D.-M. Smilgies, D. Posselt and C. M. Papadakis

Synopsis: The scattering cross section of grazing-incidence small-angle scattering from thin supported mesoscopically structured polymer films is calculated in the framework of the distorted-wave Born approximation. The two cases of parallel and perpendicular lamellar orientation are considered.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 443-445  [ doi:10.1107/S0021889806011939 ]

Si wafers having one- and two-dimensionally curved (111) planes examined by X-ray diffraction

H. Okuda, K. Nakajima, K. Fujiwara and S. Ochiai

Synopsis: Si (111) wafers deformed at elevated temperatures into cylindrical or hemispherical shapes have been examined by X-ray diffraction. The 333 peak shifts observed by scans showed that the (111) planes maintained their relationship with respect to the surface with a good crystal quality after the plastic deformation.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 446-452  [ doi:10.1107/S0021889806007072 ]

A program for automated optimization of initial crystallization conditions

T. Ben Haj Abdellatif and F. Kozielski

Synopsis: A graphical user interface to define a range of crystallization conditions for optimization of protein crystallization on a routine basis is described.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 453-457  [ doi:10.1107/S002188980600731X ]

Mercury: visualization and analysis of crystal structures

C. F. Macrae, P. R. Edgington, P. McCabe, E. Pidcock, G. P. Shields, R. Taylor, M. Towler and J. van de Streek

Synopsis: New features in the Mercury crystal structure visualizer include the display of multiple structures, atomic displacement ellipsoids, simulated powder patterns and predicted morphologies, improved control over the graphical display, and options for presenting data in tables and spreadsheets.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 458-465  [ doi:10.1107/S0021889806009915 ]

SVDdiagnostic, a program to diagnose numerical conditioning of Rietveld refinements

P. H. J. Mercier, Y. Le Page, P. S. Whitfield and L. D. Mitchell

Synopsis: Singular value decomposition tools developed here to assess the comparable numerical stability of crystallographic and crystal-chemical types of refinement described in the work by Mercier et al. [J. Appl. Cryst. (2006), 39, 369-375] have general applicability for troubleshooting problematic Rietveld refinements.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 466-467  [ doi:10.1107/S0021889806014956 ]

Ripple: a program to collect and analyze digital topographic sequences

J. J. Lovelace and G. E. O. Borgstahl

Synopsis: Software for digital topography data collection and analysis has been created.

Online 10 May 2006

 

J. Appl. Cryst. (2006). 39, 468  [ doi:10.1107/S0021889806010806 ]

A Crystallographic Information File for specular reflectivity data

A. van der Lee and I. D. Brown

Online 10 May 2006