A study of quasicrystal structure factors by using quantitative CBED

2000 ◽  
Vol 5 (1) ◽  
pp. 051-055 ◽  
Author(s):  
Zhao Chun ◽  
Zou Hua-min ◽  
Wang Ren-hui ◽  
Duan Xiao-feng ◽  
Wang Da-hai ◽  
...  
Keyword(s):  
Structure Factors ◽  
Quasicrystal Structure

Editorial Note: Inner-space reconstruction of quasicrystal structure factors

1995 ◽  
Vol 51 (9) ◽  
pp. 6184-6184
Author(s):  
Marko Vukobrat Jarić ◽  
Shi-Yue Qiu
Keyword(s):  
Editorial Note ◽  
Structure Factors ◽  
Quasicrystal Structure

Solving a 3-dimensional quasicrystal structure in 6-dimensional space using the direct method

1993 ◽  
Vol 206 (1) ◽  
Author(s):  
Fu Zheng-qing ◽  
Li Fang-hua ◽  
Fan Hai-fu
Keyword(s):  
Diffraction Data ◽  
Direct Method ◽  
Dimensional Space ◽  
Dimensional Structure ◽  
Test Results ◽  
Phase Problem ◽  
3 Dimensional ◽  
Structure Factors ◽  
A Direct Method ◽  
Quasicrystal Structure

AbstractA direct method was tested in solving the structure of a 3-dimensional quasicrystal in 6-dimensional space. Theoretical 3-dimensional diffraction data were used which contain Gaussian distribution errors with a mean error of about 20% for intensities. The diffraction data were firstly converted to a set of 6-dimensional structure factors. The window fuhction used for the conversion was measured from the Patterson origin peak in pseudo space. A direct method was then applied to solve the phase problem in 6-dimensional space. Test results showed that the procedure is very efficient.

Inner-space reconstruction of quasicrystal structure factors

1994 ◽  
Vol 49 (10) ◽  
pp. 6614-6624 ◽  
Author(s):  
Marko Vukobrat Jarić ◽  
Shi-Yue Qiu
Keyword(s):  
Structure Factors ◽  
Quasicrystal Structure

Some Applications of the U. S. Steel MVEM

1973 ◽  
Vol 31 ◽  
pp. 4-5
Author(s):  
J. S. Lally ◽  
L. E. Thomas ◽  
R. M. Fisher
Keyword(s):  
Electron Diffraction ◽  
Debye Temperature ◽  
Metals And Alloys ◽  
Critical Voltage ◽  
Dynamical Diffraction ◽  
Phase Structures ◽  
Structure Factors ◽  
Local Bonding ◽  
Diffraction Phenomenon ◽  
Multi Phase

A variety of materials containing many different microstructures have been examined with the USS MVEM. Three topics have been selected to illustrate some of the more recent studies of diffraction phenomena and defect, grain and multi-phase structures of metals and minerals.(1) Critical Voltage Effects in Metals and Alloys - This many-beam dynamical diffraction phenomenon, in which some Bragg resonances vanish at certain accelerating voltages, Vc, depends sensitively on the spacing of diffracting planes, Debye temperature θD and structure factors. Vc values can be measured to ± 0.5% in the HVEM ana used to obtain improved extinction distances and θD values appropriate to electron diffraction, as well as to probe local bonding effects and composition variations in alloys.

Isomorphous replacement in electron diffraction of wet crystals of rat hemoglobin

1983 ◽  
Vol 41 ◽  
pp. 446-447
Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons
Keyword(s):  
Electron Diffraction ◽  
Heavy Atom ◽  
Isomorphous Substitution ◽  
X Ray Diffraction ◽  
Salt Solutions ◽  
X Ray ◽  
Isomorphous Replacement ◽  
Structure Factors ◽  
Diffraction Structure ◽  
The Mean

Feasibility of isomorphous substitution in electron diffraction is supported by a calculation of the mean alteration of the electron-diffraction structure factors for hemoglobin crystals caused by substituting two mercury atoms per molecule, following Green, Ingram & Perutz, but with allowance for the proportionality of f to Z3/4 for electron diffraction. This yields a mean net change in F of 12.5%, as contrasted with 22.8% for x-ray diffraction.Use of the hydration chamber in electron diffraction opens prospects for examining many proteins that yield only very thin crystals not suitable for x-ray diffraction. Examination in the wet state avoids treatments that could cause translocation of the heavy-atom labels or distortion of the crystal. Combined with low-fluence techniques, it enables study of the protein in a state as close to native as possible.We have undertaken a study of crystals of rat hemoglobin by electron diffraction in the wet state. Rat hemoglobin offers a certain advantage for hydration-chamber work over other hemoglobins in that it can be crystallized from distilled water instead of salt solutions.

Computer processing of high-resolution images of periodic specimens

1986 ◽  
Vol 44 ◽  
pp. 2-5
Author(s):  
W. Chiu ◽  
M.F. Schmid ◽  
T.-W. Jeng
Keyword(s):  
High Resolution ◽  
Fourier Transforms ◽  
Complex Structure ◽  
Distribution Functions ◽  
Multiple Image ◽  
Cryo Electron Microscopy ◽  
Structure Factors ◽  
Unit Cells ◽  
High Resolution Images ◽  
Phase Probability Distribution

Cryo-electron microscopy has been developed to the point where one can image thin protein crystals to 3.5 Å resolution. In our study of the crotoxin complex crystal, we can confirm this structural resolution from optical diffractograms of the low dose images. To retrieve high resolution phases from images, we have to include as many unit cells as possible in order to detect the weak signals in the Fourier transforms of the image. Hayward and Stroud proposed to superimpose multiple image areas by combining phase probability distribution functions for each reflection. The reliability of their phase determination was evaluated in terms of a crystallographic “figure of merit”. Grant and co-workers used a different procedure to enhance the signals from multiple image areas by vector summation of the complex structure factors in reciprocal space.

STATIC AND DYNAMIC STRUCTURE FACTORS FOR MODELLED NORMAL 4HELIUM

1978 ◽  
Vol 39 (C6) ◽  
pp. C6-215-C6-216
Author(s):  
C. G. Harris ◽  
W.A.B. Evans
Keyword(s):  
Dynamic Structure ◽  
Structure Factors

CALCULATION OF THE PARTIAL STRUCTURE FACTORS IN BINARY LIQUID ALLOYS BY A THERMODYNAMICAL APPROACH

1980 ◽  
Vol 41 (C8) ◽  
pp. C8-586-C8-589
Author(s):  
M. Favre-Bonte ◽  
J. C. Joud ◽  
P. Hicter ◽  
P. Desre
Keyword(s):  
Liquid Alloys ◽  
Partial Structure ◽  
Binary Liquid ◽  
Structure Factors

DETERMINATION BY POLARIZED NEUTRON DIFFRACTION OF THE THREE PARTIAL STRUCTURE FACTORS OF A Co81.511B18.5 GLASS

1982 ◽  
Vol 43 (C9) ◽  
pp. C9-23-C9-29
Author(s):  
J. M. Dubois ◽  
P. Chieux ◽  
G. Le Caer ◽  
J. Schweitzer ◽  
J. Bletry
Keyword(s):  
Neutron Diffraction ◽  
Partial Structure ◽  
Structure Factors ◽  
Polarized Neutron
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