scholarly journals Quantitative extraction of morphologic cell parameters from the diffraction pattern.

1977 ◽  
Vol 25 (7) ◽  
pp. 707-718 ◽  
Author(s):  
G Seger ◽  
M Achatz ◽  
W Heinze ◽  
F Sinsel
Keyword(s):  
Fourier Analysis ◽  
Diffraction Pattern ◽  
Diffraction Plane ◽  
Cell Parameters ◽  
The Third ◽  
Exfoliated Cells ◽  
Quantitative Extraction ◽  
Diffraction Patterns ◽  
A New Technique

A new technique for the fast and quantitative extraction of cell parameters from diffraction patterns was applied to cervical gynecologic material. Based on radial scans through the diffraction pattern, this technique permits the simultaneous determination of the nuclear and cytoplasmic diameter by Fourier analysis of the radial scanning signals after compensation for the intensity falloff by an amplification which is proportional to the third power of the radial position in the diffraction plane. In addition, a correlation between the angle of the highest amplitude of the scanning signals and the coarseness of microstructures in the cell was observed. Illustrative examples of measurements on exfoliated cells of different type are presented.

The determination of unit-cell parameters from Laue diffraction patterns using their gnomonic projections

1992 ◽  
Vol 25 (2) ◽  
pp. 294-308 ◽  
Author(s):  
P. D. Carr ◽  
D. W. J. Cruickshank ◽  
M. M. Harding
Keyword(s):  
Diffraction Pattern ◽  
Unit Cell ◽  
Unit Cell Parameters ◽  
Laue Diffraction ◽  
Cell Parameters ◽  
The Absolute ◽  
Diffraction Patterns

A method is described whereby the unit cell of a crystal and its orientation can be determined from a single Laue diffraction pattern (in transmission). The axial ratios and interaxial angles can be determined precisely, but the absolute scaling of the cell depends upon the accuracy with which the minimum wavelength for the experiment is known. Several examples are given.

Determination of hydrogen ordering within the β-RH2+xphase (R= Ho, Y) using electron diffraction techniques

2000 ◽  
Vol 33 (5) ◽  
pp. 1246-1252 ◽  
Author(s):  
Elizabeth J. Grier ◽  
Amanda K. Petford-Long ◽  
Roger C. C. Ward
Keyword(s):  
Electron Diffraction ◽  
Neutron Scattering ◽  
Diffraction Pattern ◽  
Computer Simulations ◽  
Fluorite Structure ◽  
Long Range Order ◽  
Hydrogen Atoms ◽  
Ordered Structures ◽  
Diffraction Patterns

Computer simulations of the electron diffraction patterns along the [\bar{1}10] zone axes of four ordered structures within the β-RH2+xphase, withR= Ho or Y, and 0 ≤x≤ 0.25, have been performed to establish whether or not the hydrogen ordering could be detected using electron diffraction techniques. Ordered structures within otherRH2+x(R= Ce, Tb) systems have been characterized with neutron scattering experiments; however, for HoH(D)2+x, neutron scattering failed to characterize the superstructure, possibly because of the lowxconcentration or lack of long-range order within the crystal. This paper aims to show that electron diffraction could overcome both of these problems. The structures considered were the stoichiometric face-centred cubic (f.c.c.) fluorite structure (x= 0), theD1 structure (x= 0.125), theD1astructure (x= 0.2) and theD022structure (x= 0.25). In the stoichiometric structure, with all hydrogen atoms located on the tetrahedral (t) sites, only the diffraction pattern from the f.c.c. metal lattice was seen; however, for the superstoichiometric structures, with the excess hydrogen atoms ordered on the octahedral (o) sites, extra reflections were visible. All the superstoichiometric structures showed extra reflections at the (001)f.c.c.and (110)f.c.c.type positions, with structureD1 also showing extra peaks at (½ ½ ½)f.c.c.. These reflections are not seen in the simulations at similar hydrogen concentrations with the hydrogen atoms randomly occupying theovacancies.

Systematic crystallographic refinement of triclinic unit cells

1998 ◽  
Vol 13 (1) ◽  
pp. 22-31
Author(s):  
Ludo K. Frevel
Keyword(s):  
Powder Diffraction ◽  
Unit Cell ◽  
Simultaneous Equations ◽  
Unit Cell Parameters ◽  
Cell Parameters ◽  
Triclinic Phase ◽  
Unit Cells ◽  
Diffraction Patterns ◽  
Limits Of Error

Combining the exhaustive indexing of triclinic powder diffraction patterns with a crystallographic determination of unit cell parameters from pinacoid and prism reflections yields unit cell parameters with realistic limits of error. Additionally a referee method has been developed by which the six reciprocal cell parameters of a triclinic phase are determined by solving an exhaustive set of linear simultaneous equations in six unknowns.

Shadow: A System for X-ray Powder Diffraction Pattern Analysis

1988 ◽  
Vol 32 ◽  
pp. 523-530
Author(s):  
Scott A. Howard
Keyword(s):  
Diffraction Pattern ◽  
Powder Diffraction ◽  
Pattern Analysis ◽  
Shadow System ◽  
X Ray ◽  
The Third

The Shadow system consists of a set of programs and files, the relation of which is illustrated in Figures 1 and 2. Of the three programs in the system, Shadow and XRDPLT are used routinely. The third, INSCAL, is used in the determination of various parameters characterizing the instrument. Two files, Shadow.DFT and XRDPLT.DFT, contain default values for parameters controlling the reduction and display of data. A third file, WSGDAT, contains the instrument parameters.

Diffractographic moiré technique illustrated by determination of beam deflections

1973 ◽  
Vol 8 (1) ◽  
pp. 1-9 ◽  
Author(s):  
T R Pryor ◽  
O L Hageniers ◽  
W P T North
Keyword(s):  
Diffraction Pattern ◽  
Beam Deflection ◽  
Double Exposure ◽  
Beam Deflections ◽  
Diffraction Patterns

A new ‘diffractographic’ technique for measuring displacements has been developed which uses changes in the diffraction pattern of a single slit aperture formed between a fixed edge and an edge of the member itself. Described herein is an extension of the method whereby two diffraction patterns representing states of beam deflection produce moiré-type fringes of proportional spacing. Both ‘live-fringe’ and double-exposure diffractograms are shown to form these fringes and the resulting patterns directly depict deflection to within ± 0.0001 in all along the beam, over a displacement range of at least 0.1 in.

A proposed technique for quantifying muscle progesterone content in minke whales (Balaenoptera acutorostrata)

1994 ◽  
Vol 72 (2) ◽  
pp. 368-370 ◽  
Author(s):  
Motoi Yoshioka ◽  
Takuji Okumura ◽  
Katsumi Aida ◽  
Yoshihiro Fujise
Keyword(s):  
Serum Levels ◽  
Balaenoptera Acutorostrata ◽  
Minke Whales ◽  
Quantitative Extraction ◽  
A New Technique ◽  
Ethanol Extracts ◽  
Free Ranging ◽  
Near Future ◽  
Muscle Biopsies

We have developed a new technique for the quantitative extraction of progesterone from very small pieces of muscle tissue of minke whales (Balaenoptera acutorostrata) post mortem. Ethanol extracts of approximately 0.5 g of tissue contained, on average, 15.3 ng/g progesterone in the case of pregnant females (SD = 12.7, n = 9) and 0.32 ng/g progesterone in the case of immature females (SD = 0.03, n = 9). Differences in muscle progesterone levels between females in the two reproductive states were significant, as has been previously reported also for serum levels. Our technique is expected to be applicable in the near future to the determination of the presence or absence of the corpus luteum in the ovaries and the reproductive status of free-ranging female whales, provided that sampling techniques for muscle biopsies are developed.

scholarly journals Crystal structure of the thortveitite-relatedMphase, (MnxZn1–x)2V2O7(0.75

2018 ◽  
Vol 74 (10) ◽  
pp. 1079-1087
Author(s):  
Kevin M. Knowles ◽  
Anjan Sil ◽  
Berthold Stöger ◽  
Matthias Weil
Keyword(s):  
Crystal Structure ◽  
Single Crystal ◽  
X Ray Diffraction ◽  
X Ray ◽  
Cell Parameters ◽  
Distorted Version ◽  
Triclinic Structure ◽  
Diffraction Patterns ◽  
Triclinic Unit Cell

The determination of the crystal structure of theMphase, (MnxZn1–x)2V2O7(0.75 <x< 0.913), in the pseudobinary Mn2V2O7–Zn2V2O7system forx≃ 0.8 shows that the previously published triclinic unit-cell parameters for this thortveitite-related phase do not describe a true lattice for this phase. Instead, single-crystal X-ray data and Rietveld refinement of synchrotron X-ray powder data show that theMphase has a different triclinic structure in the space groupP-1 withZ= 2. As prior work has suggested, the crystal structure can be described as a distorted version of the thortveitite crystal structure of β-Mn2V2O7. A twofold superstructure in diffraction patterns of crystals of theMphase used for single-crystal X-ray diffraction work arises from twinning by reticular pseudomerohedry. This superstructure can be described as a commensurate modulation of a pseudo-monoclinic basis structure closely related to the crystal structure of β-Mn2V2O7. In comparison with the distortions introduced when β-Mn2V2O7transforms at low temperature to α-Mn2V2O7, the distortions which give rise to theMphase from the β-Mn2V2O7prototype are noticeably less pronounced.

scholarly journals Three-dimensional electron crystallography of protein microcrystals

eLife ◽  
2013 ◽  
Vol 2 ◽  
Author(s):  
Dan Shi ◽  
Brent L Nannenga ◽  
Matthew G Iadanza ◽  
Tamir Gonen
Keyword(s):  
Electron Diffraction ◽  
Protein Structures ◽  
Three Dimensional ◽  
Electron Diffraction Data ◽  
Electron Crystallography ◽  
Electron Dose ◽  
Tilt Series ◽  
Diffraction Patterns ◽  
A New Technique

We demonstrate that it is feasible to determine high-resolution protein structures by electron crystallography of three-dimensional crystals in an electron cryo-microscope (CryoEM). Lysozyme microcrystals were frozen on an electron microscopy grid, and electron diffraction data collected to 1.7 Å resolution. We developed a data collection protocol to collect a full-tilt series in electron diffraction to atomic resolution. A single tilt series contains up to 90 individual diffraction patterns collected from a single crystal with tilt angle increment of 0.1–1° and a total accumulated electron dose less than 10 electrons per angstrom squared. We indexed the data from three crystals and used them for structure determination of lysozyme by molecular replacement followed by crystallographic refinement to 2.9 Å resolution. This proof of principle paves the way for the implementation of a new technique, which we name ‘MicroED’, that may have wide applicability in structural biology.

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