No abstract

FIT2D is one of the principal area detector data reduction, analysis and visualization programs used at the European Synchrotron Radiation Facility and is also used by more than 400 research groups worldwide, including many other synchrotron radiation facilities. It has been developed for X-ray science, but is applicable to other structural techniques and is used in analysing electron diffraction data and microscopy, and neutron diffraction and scattering data. FIT2D works for both interactive and `batch'-style data processing. Calibration and correction of detector distortions, integration of two-dimensional data to a variety of one-dimensional scans, and one- and two-dimensional model fitting are the main uses. Many other general-purpose image processing and image visualization operations are available. Commands are available through a `graphical user interface' and operations common to certain types of analysis are grouped within `interfaces'. Executable versions for most workstation and personal computer systems, and web page documentation, are available at http://www.esrf.eu/computing/scientific/FIT2D.

Our electron density map is the first obtained from a natural fiber using these techniques (more commonly applied to single crystal crystallography). It reveals the three-dimensional molecular packing arrangement of type I collagen and conclusively proves that the molecules are arranged on a quasihexagonal lattice. The molecular segments that contain the telopeptides (central to the function of collagen fibrils in health and disease) have been identified, revealing that they form a corrugated arrangement of crosslinked molecules that strengthen and stabilize the native fibril.

No abstract

A modular system of techniques and software has been developed for the calibration and correction of intensity linearity, uniformity of response, spatial distortion, and image plate decay. With calibration the Molecular Dynamics TM Imaging Plate scanner system has been shown to give comparable results to the MarResearchTM scanner. The ESRF x-ray image intensifier/charge-coupled device detectors inherently cause large spatial and uniformity of response distortions, and successful data analysis depends on calibration and correction. Results of synchrotron radiation experiments are presented.