scholarly journals A wide-angle X-ray fibre diffraction method for quantifying collagen orientation across large tissue areas: application to the human eyeball coat

2013 ◽  
Vol 46 (5) ◽  
pp. 1481-1489 ◽  
Author(s):  
Jacek Klaudiusz Pijanka ◽  
Ahmed Abass ◽  
Thomas Sorensen ◽  
Ahmed Elsheikh ◽  
Craig Boote
Keyword(s):  
Collagen Fibril ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Wide Angle ◽  
Point Mapping ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Equatorial Reflection ◽  
Fibre Diffraction ◽  
Scatter Intensity

A quantitative map of collagen fibril orientation across the human eyeball coat, including both the cornea and the sclera, has been obtained using a combination of synchrotron wide-angle X-ray scattering (WAXS) and three-dimensional point mapping. A macromolecular crystallography beamline, in a custom-modified fibre diffraction setup, was used to record the 1.6 nm intermolecular equatorial reflection from fibrillar collagen at 0.5 mm spatial resolution across a flat-mounted human eyeball coat. Fibril orientation, derived as an average measure of the tissue thickness, was quantified by extraction of the azimuthal distribution of WAXS scatter intensity. Vector plots of preferential fibre orientation were remapped onto an idealized eyeball surface using a custom-built numerical algorithm, to obtain a three-dimensional representation of the collagen fibril architecture.

Revealing gross three-dimensional structure in the SEM

1987 ◽  
Vol 45 ◽  
pp. 656-657
Author(s):  
Sterling P. Newberry
Keyword(s):  
Freeze Drying ◽  
Three Dimensional ◽  
Dimensional Structure ◽  
Small Object ◽  
Final Solution ◽  
Dimensional Representation ◽  
X Ray ◽  
Three Dimensional Representation ◽  
Freeze Dried ◽  
Critical Point Drying

The beautiful three dimensional representation of small object surfaces by the SEM leads one to search for ways to open up the sample and look inside. Could this be the answer to a better microscopy for gross biological 3-D structure? We know from X-Ray microscope images that Freeze Drying and Critical Point Drying give promise of adequately preserving gross structure. Can we slice such preparations open for SEM inspection? In general these preparations crush more readily than they slice. Russell and Dagihlian got around the problem by “deembedding” a section before imaging. This some what defeats the advantages of direct dry preparation, thus we are reluctant to accept it as the final solution to our problem. Alternatively, consider fig 1 wherein a freeze dried onion root has a window cut in its surface by a micromanipulator during observation in the SEM.

In Situ Three-Dimensional Orientation Mapping in Plastically-Deformed Polycrystalline Iron by Three-Dimensional X-Ray Diffraction

2014 ◽  
Vol 777 ◽  
pp. 118-123 ◽  
Author(s):  
Yujiro Hayashi ◽  
Yoshiharu Hirose ◽  
Daigo Setoyama
Keyword(s):  
Three Dimensional ◽  
Diffraction Method ◽  
Inverse Pole Figure ◽  
Coarse Grained ◽  
Uniaxial Tensile ◽  
X Ray Diffraction ◽  
Polycrystalline Iron ◽  
X Ray ◽  
Orientation Mapping

In situ three-dimensional crystallographic orientation mapping in plastically-deformed polycrystalline iron is demonstrated using a modified three-dimensional x-ray diffraction method. This voxel-by-voxel measurement method enables the observation of intragranular orientation distribution. The experiment is performed using coarse-grained ferrite with a mean grain size of ~ 60 μm and an incident x-ray beam with a beam size of 20 μm × 20 μm. Grains averagely rotate approximately toward the <110> preferred orientation of body-centered cubic uniaxial tensile texture. Intragranular orientation distributions are spread as the tensile strain increases to 10.7 %. Furthermore, intragranular multidirectional rotations are observed in grains near the <100> and <111> corners in the inverse pole figure.

The phase problem for one-dimensional crystals

2017 ◽  
Vol 73 (2) ◽  
pp. 140-150 ◽  
Author(s):  
Rick P. Millane
Keyword(s):  
A Priori ◽  
Three Dimensional ◽  
Phase Problem ◽  
One Dimensional ◽  
X Ray ◽  
Additional Information ◽  
Laser Sources ◽  
Fibre Diffraction ◽  
Low Dimensional ◽  
Molecular Envelope

The phase problem for diffraction amplitudes measured from a one-dimensional crystal is examined. In the absence of anya prioriinformation, the solution to this problem is shown to be unique up to a parameterized, low-dimensional set of solutions. Minimal additionala prioriinformation is expected to render the solution unique. The effects of additional information such as positivity, molecular envelope and helical symmetry on uniqueness are characterized. The results are pertinent to structural studies of polymeric and rod-like biomolecular assemblies that form one-dimensional, rather than three-dimensional, crystals. This shows the potential forab initiophasing of diffraction data from single such assemblies measured using new X-ray free-electron laser sources. Such an approach would circumvent the complicated inversion of cylindrically averaged diffraction that is necessary in traditional X-ray fibre diffraction analysis.

Structure of the collagen fibril: some variations on a theme of tetragonally packed dimers

1980 ◽  
Vol 209 (1175) ◽  
pp. 275-297 ◽  
Keyword(s):  
Self Assembly ◽  
Collagen Fibril ◽  
Three Dimensional ◽  
Local Property ◽  
Square Lattice ◽  
Dimensional Structure ◽  
X Ray Diffraction ◽  
X Ray ◽  
Variations On A Theme ◽  
Overlap Region

A theory of the three-dimensional structure of the collagen fibril outlined by Woodhead-Galloway (1977) is discussed in greater detail and an account of the low angle X-ray diffraction pattern (Miller & Wray 1971) is obtained. Square-packed dimers form the overlap region of the fibril. In the gap region, clusters of four dimers at each of the points of a square lattice of side 3.8 nm provide the structure. Molecules are parallel to the axis of the fibril in the overlap region and tilted from the axis by a few degrees in the gap region. A brief discussion of some aspects of the self assembly of such a structure is included. In particular, it is noted that the axially projected D ( ═ 66.8 nm) period, which is a property of the Whole fibril, is not necessarily also a local property; there may be no well defined and finite small grouping of molecules that is itself D -periodic, such as is proposed in the microfibril model of the fibril (Smith 1968). On the other hand, there is strong circumstantial evidence of a D -periodic crystallographic unit cell.

Study of The Hydrothermal Synthesis of Gallium Phosphates Using in Situ Time-Resolved X-Ray Diffraction

1998 ◽  
Vol 547 ◽  
Author(s):  
R.I. Walton ◽  
T. Loiseau ◽  
R.J. Francis ◽  
D. O'Hare ◽  
G. Férey
Keyword(s):  
Kinetic Data ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Effect Of Temperature ◽  
X Ray Diffraction ◽  
Hydrothermal Conditions ◽  
Time Resolved ◽  
X Ray ◽  
Phosphorus Source

AbstractThe hydrothermal crystallisation (130-180 °C) of three-dimensional open-framework gallium and aluminium oxyfluoro-phosphates with the ULM-3 and ULM-4 structures have been studied in situ for the first time. The in situ energy-dispersive X-ray diffraction method has allowed the formation of the crystalline products to be observed under hydrothermal conditions The integrated areas of the strongest Bragg reflections has allowed quantitative kinetic data to be extracted. The effect of temperature, phosphorus source, templating agent have been investigated. The nature of phosphorus source in the reaction mixture has been found to affect dramatically the course of reaction for certain combinations of amine and temperature. Previously unobserved transient crystalline phases have been seen during the production of ULM-3 gallium phosphates when P2O5 or polyphosphoric acid are used. The formation of these intermediates affects the kinetics of product growth. In the case of the aluminium ULM-3 materials reaction always proceeds via a crystalline intermediate whatever phosphorus source is used. The ULM-4 framework materials are found to always crystallise directly with no evidence for any intermediates. Kinetic data for each system have been modelled using standard solid-state chemistry expressions, and these calculations indicate the reactions to be diffusion controlled.

scholarly journals X-ray diffraction studies of enkephalins. Crystal structure of [(4′-bromo) Phe4,Leu5]enkephalin

1984 ◽  
Vol 218 (3) ◽  
pp. 677-689 ◽  
Author(s):  
T Ishida ◽  
M Kenmotsu ◽  
Y Mino ◽  
M Inoue ◽  
T Fujiwara ◽  
...  
Keyword(s):  
Crystal Structure ◽  
Least Squares Method ◽  
Heavy Atom ◽  
Three Dimensional ◽  
Diffraction Method ◽  
Biologically Active ◽  
Type I ◽  
X Ray Diffraction ◽  
X Ray ◽  
Relationship Of

In order to investigate the structure-activity relationship of [Leu5]- and [Met5]enkephalins, [(4′-bromo)Phe4, Leu5]-, [(4′-bromo)Phe4, Met5]- and [Met5] enkephalins were synthesized and crystallized. The crystal structure of [(4′-bromo) Phe4, Leu5]- enkephalin was determined by X-ray diffraction method using the heavy atom method and refined to R = 0.092 by the least-squares method. The molecule in this crystal took essentially the same type I' beta-turn conformation found in [Leu5]enkephalin [Smith & Griffin (1978) Science 199, 1214-1216). On the other hand, the preliminary three-dimensional Patterson analyses showed that the most probable conformations of [(4′-bromo)Phe4,Met5]- and [Met5]enkephalins are both the dimeric extended forms. Based on these insights, the biologically active conformation of enkephalin was discussed in relation to the mu- and delta-receptors.

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