Journal of Applied Crystallography

Volume 41, Part 6 (December 2008)

	Cover illustration: Two-dimensional grazing-incidence X-ray scattering pattern for a PS-b-PI thin film deposited on a silicon substrate. Courtesy of Sangwoo Jin et al. [J. Appl. Cryst. (2007), 40, 950-958].

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

research papers

J. Appl. Cryst. (2008). 41, 975-984  [ doi:10.1107/S0021889808028185 ] Symmetry determination following structure solution in P1 L. Palatinus and A. van der Lee Synopsis: A new method for space-group determination is described that is based on a symmetry analysis of the scattering-density map resulting from the structure solution in space group P1. Online 11 October 2008

J. Appl. Cryst. (2008). 41, 985-990  [ doi:10.1107/S0021889808029944 ] X-ray powder diffraction quantitative analysis of an amorphous SiO2-poly(methyl methacrylate) nanocomposite P. Riello, M. Munarin, S. Silvestrini, E. Moretti and L. Storaro Synopsis: A new technique based on X-ray powder diffraction has been developed for quantitative analysis of multiphase amorphous materials. The feasibility of the new method is demonstrated for an amorphous SiO2-poly(methyl methacrylate) hybrid nanocomposite. Online 11 October 2008

J. Appl. Cryst. (2008). 41, 991-1002  [ doi:10.1107/S0021889808029579 ] A comparative in situ Rietveld refinement study: thermal decomposition and transformation of CoAl and CoZnAl layered double hydroxides R. E. Johnsen and P. Norby Synopsis: Rietveld refinement based on in situ synchrotron X-ray powder diffraction data was combined with thermogravimetric analysis and mass spectrometry to study and compare the microstructural and structural changes of the initial layered double hydroxides and their decomposition oxides. Online 25 October 2008

J. Appl. Cryst. (2008). 41, 1003-1008  [ doi:10.1107/S0021889808032858 ] Neutron transmission of single-crystal magnesium fluoride J. G. Barker, D. F. R. Mildner, J. A. Rodriguez and P. Thiyagarajan Synopsis: Single-crystal magnesium fluoride is useful as a short-wavelength epithermal neutron filter. The neutron attenuation coefficient has been measured at temperatures of 293 and 77 K. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1009-1018  [ doi:10.1107/S0021889808032718 ] X-ray absorption spectroscopy studies of phase transformations and amorphicity in nanotitania powder and silica-titania core-shell photocatalysts S. H. Lim, N. Phonthammachai, T. Liu and T. J. White Synopsis: The anatase-to-rutile transformation in photocatalytic titanias is reconstructive and proceeds via an abundant and persistent amorphous form that may enhance performance by creating higher surface area materials that also retard exciton recombination. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1019-1023  [ doi:10.1107/S0021889808030732 ] Statistical properties of measured X-ray intensities affected by counting loss T. Ida Synopsis: The statistical properties of X-ray intensities measured with counting systems were experimentally investigated by repeated measurements based on Chipman's foil method. It is shown that the observed statistical variance can be well reproduced by a formula derived from an intermediately extended dead-time model for counting loss. Online 15 November 2008

J. Appl. Cryst. (2008). 41, 1024-1037  [ doi:10.1107/S0021889808030112 ] A novel pole figure inversion method: specification of the MTEX algorithm R. Hielscher and H. Schaeben Synopsis: A novel algorithm for orientation density function estimation from diffraction pole figures is presented which is especially well suited for sharp textures and high-resolution pole figures measured with respect to arbitrarily scattered specimen directions, e.g. by area detectors. Online 15 November 2008

J. Appl. Cryst. (2008). 41, 1038-1045  [ doi:10.1107/S0021889808028562 ] Total-scattering-based automatic centring of capillary samples within powder diffractometers L. M. D. Cranswick and R. L. Donaberger Synopsis: A computer-controlled method for the automatic mechanical centring of a powder capillary sample onto the rotation centre of a powder diffractometer, using total scattering of the radiation beam into one-dimensional or two-dimensional detectors and only a 90° rotation of the sample stage, is described. Online 11 October 2008

J. Appl. Cryst. (2008). 41, 1046-1052  [ doi:10.1107/S0021889808028264 ] Reconstructing three-dimensional shape envelopes from time-resolved small-angle X-ray scattering data J. Lamb, L. Kwok, X. Qiu, K. Andresen, H. Y. Park and L. Pollack Synopsis: The three-dimensional reconstruction program DAMMIN has been applied to time-resolved small-angle X-ray scattering data. The results are presented and their success in representing the molecules is assessed. Online 11 October 2008

J. Appl. Cryst. (2008). 41, 1053-1056  [ doi:10.1107/S0021889808029981 ] DuMond analysis of bending in single crystals by Laue diffraction using - polarization geometry J. Serrano, C. Ferrero, M. Servidori, J. Härtwig and M. Krisch Synopsis: A three-dimensional DuMond formalism is proposed for a - polarization geometry and a combined Bragg-Laue diffraction, and is employed to quantify the bending of single-crystal analysers. Online 11 October 2008

J. Appl. Cryst. (2008). 41, 1057-1066  [ doi:10.1107/S002188980802935X ] X-ray tomographic reconstruction of macromolecular samples S. Brockhauser, M. Di Michiel, J. E. McGeehan, A. A. McCarthy and R. B. G. Ravelli Synopsis: High-resolution X-ray tomography is used to reconstruct three-dimensional volumes of vitrified macromolecular crystals. Online 11 October 2008

J. Appl. Cryst. (2008). 41, 1067-1075  [ doi:10.1107/S0021889808031026 ] Determination of depth gradients of grain interaction and stress in Cu thin films M. Wohlschlögel, W. Baumann, U. Welzel and E. J. Mittemeijer Synopsis: The depth gradients of grain interaction and stress in Cu thin films were determined by X-ray diffraction stress measurements at fixed penetration depths. The effects of the surface roughness and the refraction of the incident beam were illustrated on the basis of a comparison of synchrotron and laboratory measurements, utilizing the corresponding variation in wavelength for tuning the absorption. Online 25 October 2008

J. Appl. Cryst. (2008). 41, 1076-1088  [ doi:10.1107/S0021889808030823 ] Benefits of two-dimensional detectors for synchrotron X-ray diffraction studies of thin film mechanical behavior G. Geandier, P.-O. Renault, S. Teat, E. Le Bourhis, B. Lamongie and P. Goudeau Synopsis: A methodology using synchrotron X-rays and two-dimensional detectors to study the mechanical properties of thin films is presented. Online 25 October 2008

J. Appl. Cryst. (2008). 41, 1089-1094  [ doi:10.1107/S0021889808030872 ] A differential thermal expansion approach to crystal structure determination from powder diffraction data P. Fernandes, K. Shankland, W. I. F. David, A. J. Markvardsen, A. J. Florence, N. Shankland and C. K. Leech Synopsis: A strategy for improving the chances of solving molecular crystal structures from powder diffraction data using direct methods is outlined. Online 25 October 2008

J. Appl. Cryst. (2008). 41, 1095-1108  [ doi:10.1107/S0021889808031762 ] Microstrain and grain-size analysis from diffraction peak width and graphical derivation of high-pressure thermomechanics Y. Zhao and J. Zhang Synopsis: By analyzing diffraction peak profiles at different P-T loading stages, the thermomechanical properties of materials can be derived, with graphical delineations of micro/macro yields, plastic flow, energy dissipation, work hardening/softening, grain crushing/growth, stress relaxation and residual strain, as well as instrument baselines for all diffraction modes. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1109-1114  [ doi:10.1107/S0021889808031488 ] Determination of directionally dependent structural and microstructural information using high-energy X-ray diffraction J. E. Daniels Synopsis: A method for solving the direction of structural and microstructural perturbations using high-energy X-ray diffraction is demonstrated. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1115-1121  [ doi:10.1107/S0021889808034377 ] Combining precession electron diffraction data with X-ray powder diffraction data to facilitate structure solution D. Xie, C. Baerlocher and L. B. McCusker Synopsis: By supplementing high-resolution X-ray powder diffraction data with information derived from precession electron diffraction data, increasingly complex structures of polycrystalline materials can be solved. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1122-1133  [ doi:10.1107/S0021889808032536 ] Is your cold-stream working for you or against you? An in-depth look at temperature and sample motion R. W. Alkire, N. E. C. Duke and F. J. Rotella Synopsis: An investigation was conducted into the temperature and vibration profiles from a commercial cold-stream. Based on these results suggestions are made on how to align a cold-stream, the importance of cold-stream placement to minimize sample motion and how to look at data processing statistics to see if sample motion is affecting data quality. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1134-1139  [ doi:10.1107/S0021889808031129 ] Scatterless hybrid metal-single-crystal slit for small-angle X-ray scattering and high-resolution X-ray diffraction Y. Li, R. Beck, T. Huang, M. C. Choi and M. Divinagracia Synopsis: A hybrid design consisting of a single-crystal tip bonded to a tapered metal base with a large tilt angle to the beam practically eliminates parasitic slit scattering in X-ray diffraction apparatus, leading to a single-aperture small-angle X-ray scattering instrument design with enhanced intensity and higher resolution. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1140-1149  [ doi:10.1107/S0021889808033384 ] Optimal local axes and symmetry assignment for charge-density refinement S. Domagala and C. Jelsch Synopsis: Local axes systems are generated for multipole orientation in order to take the symmetry of the atoms fully into account. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1150-1160  [ doi:10.1107/S0021889808033797 ] The use of blue native PAGE in the evaluation of membrane protein aggregation states for crystallization J. Ma and D. Xia Synopsis: Monodispersity obtained by the blue native PAGE (BN-PAGE) gel for membrane proteins correlates well with their propensity to crystallize. The results from BN-PAGE are more informative on the sample aggregation states in solution than other techniques such as dynamic light scattering and size exclusion chromatography. BN-PAGE is also particularly useful for efficient detergent selection for membrane protein crystallization. Online 11 November 2008

teaching and education

J. Appl. Cryst. (2008). 41, 1161-1172  [ doi:10.1107/S0021889808032494 ] A tutorial for learning and teaching macromolecular crystallography A. Faust, S. Panjikar, U. Mueller, V. Parthasarathy, A. Schmidt, V. S. Lamzin and M. S. Weiss Synopsis: A tutorial consisting of five macromolecular crystallography experiments has been assembled for teaching purposes. The described work comprises the crystallization of the proteins, diffraction data collection, data processing and automated structure determination. Online 11 November 2008

computer programs

J. Appl. Cryst. (2008). 41, 1173-1176  [ doi:10.1107/S0021889808028938 ] AutoSherlock: a program for effective crystallization data analysis R. M. Nagel, J. R. Luft and E. H. Snell Synopsis: AutoSherlock is a program that visually represents results from the Hauptman-Woodward High-Throughput Crystallization Screening Service in chemical space. It thereby aids in the determination and further optimization of crystallization conditions. Online 11 October 2008

J. Appl. Cryst. (2008). 41, 1177-1181  [ doi:10.1107/S0021889808031087 ] ExtSym: a program to aid space-group determination from powder diffraction data A. J. Markvardsen, K. Shankland, W. I. F. David, J. C. Johnston, R. M. Ibberson, M. Tucker, H. Nowell and T. Griffin Synopsis: It is shown that ExtSym can be used successfully with many well known powder diffraction analysis packages. In addition, a precise description of the optimal input for ExtSym is given to enable other software packages to interface with it. Online 25 October 2008

J. Appl. Cryst. (2008). 41, 1182-1186  [ doi:10.1107/S0021889808034390 ] From space to superspace and back: Superspace Group Finder I. Orlov, L. Palatinus and G. Chapuis Synopsis: A database linking (3 + 1)-dimensional superspace and three-dimensional space groups derived from real-space rational sections has been compiled and made available through a web-based application. Online 11 November 2008

J. Appl. Cryst. (2008). 41, 1187-1193  [ doi:10.1107/S0021889808032445 ] Stochastic fitting of specular X-ray reflectivity data using StochFit S. M. Danauskas, D. Li, M. Meron, B. Lin and K. Y. C. Lee Synopsis: StochFit provides stochastic model-dependent and model-independent fitting routines for analyzing specular X-ray reflectivity data. Additionally, StochFit provides an intuitive and unique method of utilizing a model-independent fit to determine a model-dependent fit. Online 11 November 2008

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