Journal of Applied Crystallography

Volume 40, Part 6 (December 2007)

	Cover illustration: Molecular electrostatic potential of thymidine mapped on the charge density isosurface at 0.5 e Å-3 using MolIso. Courtesy of C. B. Huebschle & P. Luger [J. Appl. Cryst. (2006), 39, 901-904].

• research papers
• teaching and education
• short communications
• computer programs
• meetings

research papers

J. Appl. Cryst. (2007). 40, 975-985  [ doi:10.1107/S0021889807038174 ] Aspects of the modelling of the radial distribution function for small nanoparticles V. I. Korsunskiy, R. B. Neder, A. Hofmann, S. Dembski, C. Graf and E. Rühl Synopsis: The structures of ZnSe and CdSe/ZnS core/shell nanoparticle samples have been studied by analysing the radial distribution functions. Methods are presented to calculate the radial distribution functions of these nanoparticle types. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 990-998  [ doi:10.1107/S002188980704174X ] X-ray extinction changes due to dislocations M. Masimov Synopsis: A procedure for determination of dislocation density in weakly distorted crystals by means of X-ray extinction measurements is proposed. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 999-1007  [ doi:10.1107/S0021889807042379 ] In situ synchrotron powder diffraction study of active belite clinkers Á. G. De la Torre, K. Morsli, M. Zahir and M. A. G. Aranda Synopsis: The chemical reactions and transformations accompanying clinkerization have been followed in situ by X-ray synchrotron powder diffraction at temperatures between 1200 and 1700 K. All patterns have been evaluated by the Rietveld method to obtain quantitative phase analyses. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1008-1018  [ doi:10.1107/S0021889807044378 ] Interpretation of small-angle X-ray scattering patterns of crystalline triglyceride nanoparticles in dispersion T. Unruh Synopsis: Dispersions of triglyceride nanocrystals exhibit complex small-angle X-ray diffraction patterns due to the occurrence of different structural features on similar length scales. A novel computer-aided data analysis method is introduced and applied successfully to SAXS patterns of phospholipid-stabilized tripalmitin nanosuspensions. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1019-1026  [ doi:10.1107/S0021889807045244 ] Least-squares thermal expansion tensor of vanadate and arsenate triclinic apatites derived from laboratory X-ray powder diffraction cell data P. S. Whitfield, Y. Le Page, P. H. J. Mercier and J. Y. Kim Synopsis: Applied to in-lab X-ray powder cell data for triclinic vanadate and arsenate apatites, a novel and simple method for the least-squares extraction of the thermal expansion tensor shows that both materials contract considerably along [24] upon heating. Reversible phase transitions observed at, respectively, 453 and 583 K are attributed to mobility of contact surfaces between triclinic twins within mosaic blocks. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1035-1038  [ doi:10.1107/S0021889807044901 ] Application of the constrained S-FFT direct-phasing method to powder diffraction data. XIII J. Rius and C. Frontera Synopsis: A simple and completely general phasing procedure (S-FFT) has been developed that maximizes the direct-methods origin-free modulus sum function S by means of the FFT algorithm. An algorithm combining the S-FFT procedure with real-space constraints according to the Shake-and-Bake philosophy is given and its capability to treat powder diffraction data is proved with some realistic test structures. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1039-1043  [ doi:10.1107/S0021889807048236 ] Temperature dependence of the crystal structure of -AgSCN by powder neutron diffraction D. J. Williams, L. L. Daemen, S. C. Vogel and Th. Proffen Synopsis: A structural study of -AgSCN was carried out using the neutron powder diffractometer HIPPO (high-pressure preferred orientation powder) at ten different temperatures between 25 and 275 K. -AgSCN is unusual in that it has an ordered structure with no disorder in the orientation of the anionic ligands. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1044-1049  [ doi:10.1107/S0021889807048339 ] TRY, a new computer program for crystal structure analysis from diffraction data based on internal coordinates and on a molecular modelling procedure free of redundant coordinates A. Immirzi Synopsis: A program for modelling intricate molecules based on refinement of internal coordinates is described. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1050-1055  [ doi:10.1107/S0021889807044482 ] On the intersection of grating truncation rods with the Ewald sphere studied by grazing-incidence small-angle X-ray scattering M. Yan and A. Gibaud Synopsis: The precise location of the intersection of the grating truncation rods with the Ewald sphere of a grating is calculated for any azimuthal angle by grazing-incidence small-angle X-ray scattering. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1056-1063  [ doi:10.1107/S0021889807038253 ] A new design for the standard pinhole small-angle neutron scattering instrument D11 K. Lieutenant, P. Lindner and R. Gahler Synopsis: Monte Carlo simulations show that improved guide characteristics, a diverging trumpet at the beginning of the guide system and a converging guide at the end (maybe with a variable trumpet) promise a considerable improvement of the performance of D11 or other pinhole small-angle neutron scattering (SANS) instruments with the converging trumpet overcoming disadvantages for small collimation distances caused by the diverging trumpet. The use of a glass guide to reduce background is a good concept for SANS instruments. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1064-1075  [ doi:10.1107/S0021889807040010 ] Evidence for the presence of U-Mo-Al ternary compounds in the U-Mo/Al interaction layer grown by thermal annealing: a coupled micro X-ray diffraction and micro X-ray absorption spectroscopy study H. Palancher, P. Martin, V. Nassif, R. Tucoulou, O. Proux, J.-L. Hazemann, O. Tougait, E. Lahéra, F. Mazaudier, C. Valot and S. Dubois Synopsis: This work demonstrates the very low Mo solubility in UAl3 and UAl4 binary phases; it contradicts the hypothesis of the formation of (U,Mo)Al3 and (U,Mo)Al4 often presented in the literature. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1076-1088  [ doi:10.1107/S0021889807040149 ] On the precision and accuracy of structural analysis of light-induced metastable states V. Legrand, S. Pillet, H.-P. Weber, M. Souhassou, J.-F. Létard, P. Guionneau and C. Lecomte Synopsis: The biases in the structural analysis of light-induced molecular metastable states are quantitatively investigated using simulated and experimental data for the spin-crossover complex [Fe(phen)2(NCS)2]. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1089-1096  [ doi:10.1107/S0021889807041003 ] Application of white-beam X-ray microdiffraction for the study of mineralogical phase identification in ancient Egyptian pigments P. A. Lynch, N. Tamura, D. Lau, I. Madsen, D. Liang, M. Strohschnieder and A. W. Stevenson Synopsis: The method of white-beam X-ray microdiffraction has been extended to obtain phase information from samples that exhibit a heterogeneous mineralogy. By indexation of the complex Laue patterns, demonstration of the white-beam methodology is applied to determine the mineralogy of colour pigments from an ancient Egyptian coffin. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1097-1104  [ doi:10.1107/S0021889807042045 ] In situ X-ray diffraction analysis of (CFx)n batteries: signal extraction by multivariate analysis M. A. Rodriguez, M. R. Keenan and G. Nagasubramanian Synopsis: Application of multivariate analysis to in situ X-ray diffraction data sets shows great promise for extraction of weak diffraction signals. The mathematical treatment of the data set enables separation into individual components, thus enabling a more straightforward investigation of dynamic reaction behavior. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1105-1112  [ doi:10.1107/S0021889807044196 ] Advances in spectroscopic methods for biological crystals. 1. Fluorescence lifetime measurements A. Royant, P. Carpentier, J. Ohana, J. McGeehan, B. Paetzold, M. Noirclerc-Savoye, X. Vernède, V. Adam and D. Bourgeois Synopsis: An improved version of the microspectrophotometer of the ESRF `Cryobench' laboratory is described, and the implementation of a fluorescence lifetime measurement system suitable for crystals or nanolitre-sized solution samples is reported. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1113-1122  [ doi:10.1107/S0021889807044202 ] Advances in spectroscopic methods for biological crystals. 2. Raman spectroscopy P. Carpentier, A. Royant, J. Ohana and D. Bourgeois Synopsis: A Raman microspectrophotometer is described that allows the investigation of protein crystals under the same experimental conditions as those used for X-ray diffraction. Examples highlight the outstanding quality of Raman spectra recorded in protein crystals under non-resonant conditions, and demonstrate the interest of the technique as a complementary tool to macromolecular crystallography. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1123-1134  [ doi:10.1107/S0021889807045219 ] A comparison of protein models obtained by small-angle X-ray scattering and crystallography H. Durchschlag, P. Zipper and A. Krebs Synopsis: SAXS-based protein models can be obtained by conventional or ab initio approaches. The comparison of these models with those obtained from crystallography shows far-reaching agreement, even in the case of giant proteins. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1135-1145  [ doi:10.1107/S0021889807048571 ] Variable-temperature X-ray crystal structure determinations of {Fe[tren(6-Mepy)3]}(ClO4)2 and {Zn[tren(6-Mepy)3]}(ClO4)2 compounds: correlation of the structural data with magnetic and Mössbauer spectroscopy data M. Seredyuk, A. B. Gaspar, J. Kusz, G. Bednarek and P. Gütlich Synopsis: Variable-temperature X-ray crystal structure determinations (80-330 K) on {Fe[tren(6-Mepy)3]}(ClO4)2 (1-Fe) and {Zn[tren(6-Mepy)3]}(ClO4)2 (1-Zn) were carried out together with a detailed analysis of the unit-cell volume and parameters in the spin transition region for (1-Fe). The variation in metal-ligand bond lengths, the distortion parameters, as well as the cell parameters are very close to the character of the magnetic curve and the curve of HS derived from the Mössbauer data which shows the correlation between structure and physical properties in (1-Fe). Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1146-1152  [ doi:10.1107/S0021889807043580 ] On the role of nitrogen in stiffening the diamond structure S. G. Nailer, M. Moore, J. Chapman and G. Kowalski Synopsis: By a combination of synchrotron X-ray diffraction and optical studies, it is concluded that incorporation of nitrogen into natural diamond during growth stiffens the structure against plastic deformation. Online 10 November 2007

teaching and education

J. Appl. Cryst. (2007). 40, 1153-1165  [ doi:10.1107/S0021889807043622 ] Illustrated Fourier transforms for crystallography E. Aubert and C. Lecomte Synopsis: Concepts such as Fourier transformation, convolution and resolution that are required to understand crystallography are illustrated through visual examples. Online 10 November 2007

short communications

J. Appl. Cryst. (2007). 40, 1166-1168  [ doi:10.1107/S0021889807048637 ] Structural investigation of the cubic perovskite-type doped lanthanum cobaltite La0.6Sr0.4CoO3- at 1531 K: possible diffusion path of oxygen ions in an electrode material M. Yashima and T. Tsuji Synopsis: The crystal structure of a cubic perovskite-type doped lanthanum cobaltite, La0.6Sr0.4CoO3-, has been studied using in situ neutron powder diffraction data measured at 1531 K. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1169-1173  [ doi:10.1107/S0021889807048285 ] Characterization of polycapillary X-ray lens for application in confocal three-dimensional energy-dispersive micro X-ray diffraction experiments T. Sun, M. Zhang, X. Ding, Z. Liu, X. Lin and H. Liu Synopsis: The application of the polycapillary X-ray optics in confocal three-dimensional energy-dispersive micro X-ray diffraction experiments is studied. Online 10 November 2007

computer programs

J. Appl. Cryst. (2007). 40, 1174-1178  [ doi:10.1107/S0021889807045086 ] GenX: an extensible X-ray reflectivity refinement program utilizing differential evolution M. Björck and G. Andersson Synopsis: A program for refinement of reflectivity data using a genetic algorithm, differential evolution, is presented. The program is capable of simulating diffuse and specular X-ray reflectivity, as well as neutron reflectivity with or without magnetic contrast including spin-flip scattering. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1179-1182  [ doi:10.1107/S0021889807048741 ] GenOVa: a computer program to generate orientational variants C. Cayron Synopsis: This computer program calculates the orientational variants, the operators and the composition table of a groupoid. Online 10 November 2007

J. Appl. Cryst. (2007). 40, 1183-1188  [ doi:10.1107/S0021889807048777 ] ARPGE: a computer program to automatically reconstruct the parent grains from electron backscatter diffraction data C. Cayron Synopsis: A computer program has been written to reconstruct the parent grains from EBSD data of phase transition materials. Online 10 November 2007

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