Journal of Applied Crystallography

Aspden, R.M; Hukins, D.W.L

doi: 10.1107/S0021889879012516pmid: N/A

A quantitative technique is described for determining the direction of preferred orientation and the orientation distribution function of collagen fibrils in connective tissues from high-angle X-ray diffraction patterns. In principle, the direction of preferred orientation is parallel to the orientation of the meridian on the diffraction pattern; in practice, the orientation of the equator, which is perpendicular to the meridian and is more clearly defined, is used to deduce this direction. The angular dependence of the equatorial intensity distribution is measured at a convenient radius on a pattern. The same measurements are made on a pattern from elastoidin spicules, which consist of effectively perfectly oriented collagen molecules. Deconvolution of the former by the latter yields the orientation distribution function. This deconvolution is achieved in Fourier-transform space where the equivalent operation is simply division; inverse transformation yields the required result. Measurements and analysis were performed with a program written for the Joyce Loebl Magiscan Image Analysis System.

Mullica, D.F; Beall, G.W; Milligan, W.O; Oliver, J.D

doi: 10.1107/S0021889879012449pmid: N/A

A structural refinement of ammonium hydrogen tartrate, C4H9NO6, has been completed from data obtained on an Enraf-Nonius CAD-4 X-ray diffractometer equipped with a Si(Li) solid-state detector. The refinement has given comparable results with those found in the literature. A comparative study of a select number of weak reflections obtained from this study and from the results of an analysis using a conventional scintillation system indicates that the peak-to-background ratio is better for intensity data collected on an X-ray diffractometer using a Si(Li) solid-state detector system. An important application of a Si(Li) energy-dispersive system is X-ray fluorescence analysis which can be performed on the same single-crystal employed in X-ray diffraction data collection. Qualitative determinations and quantiative data on relative percentages of metal constituents have been obtained from single crystals of Lu(OH)3 and Mn3Co(CN)62.12H2O in less than two hours.

Bursill, L. A.; Spargo, A. E. C.; Wentworth, D.; Wood, G.

doi: 10.1107/S0021889879012474pmid: N/A

The design, operating principles and constructional details of a goniometer for use in ultra‐high‐resolution objective‐lens pole‐pieces are described. Image‐matching of experimental and computer‐simulated high‐resolution electron micrographs is used to demonstrate an instrumental resolution of 1.6 Å, point‐to‐point.

Muller, J.J; Damaschun, G

doi: 10.1107/S0021889879012450pmid: N/A

The filter theory allows one to compare the efficiencies of smoothing procedures widely used in the field of small-angle X-ray scattering. This method is demonstrated for polynomial fitting and modified frequency filtering. Optimized and objective smoothing parameters are determined for both procedures through the knowledge of variance reduction factors, transfer functions of the filters, the largest value of the spatial frequencies of the scattering curve and the distortions caused by the smoothing procedures. The comparison of the efficiency of polynomial fitting and frequency filtering clearly shows the superiority of the latter; therefore, this method has to be preferred.

Bradaczek, H; Denzer, P; Labischinski, H

doi: 10.1107/S0021889879012541pmid: N/A

doi: 10.1107/S0021889879012553pmid: N/A

Miyata, T.; Ishizawa, N.; Minato, I.; Iwai, S.‐I.

doi: 10.1107/S0021889879012504pmid: N/A

Gas‐flame specimen‐heating equipment has been designed and constructed for structural investigations of materials which are not chemically affected by exposure to the combustion gas. The heating equipment is attachable to any standard four‐circle diffractometer, preserving all the functions of the diffractometer, and provides specimen temperatures up to 2600 K. The ventilation of the hot exhaust gas and the use of a small flame prevent the elevation of temperature at any part of the diffractometer. The maintenance of high temperatures is controlled by constant gas flow and the temperature is stable within ± 15 K at temperatures between 1800 and 2600 K. The intensity data of an α‐Al2O3 single‐crystal were successfully collected at 2173 K.

Nelson, J.

doi: 10.1107/S0021889879012607pmid: N/A

Bursill, L.A; Spargo, A.E.C; Wentworth, D; Wood, G

doi: 10.1107/S0021889879012474pmid: N/A

The design, operating principles and constructional details of a goniometer for use in ultra-high-resolution objective-lens pole-pieces are described. Image-matching of experimental and computer-simulated high-resolution electron micrographs is used to demonstrate an instrumental resolution of 1.6 A, point-to-point.

doi: 10.1107/S0021889879012577pmid: N/A