scholarly journals Computation of static quantum triplet structure factors of liquid para-hydrogen

2018 ◽  
Vol 149 (12) ◽  
pp. 124507 ◽  
Author(s):  
Luis M. Sesé
2016 ◽  
Vol 93 (2) ◽  
Author(s):  
Minh-Tan Nguyen ◽  
Vincent Monchiet ◽  
Guy Bonnet ◽  
Quy-Dong To

Author(s):  
J. S. Lally ◽  
L. E. Thomas ◽  
R. M. Fisher

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.


Author(s):  
William F. Tivol ◽  
Murray Vernon King ◽  
D. F. Parsons

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.


Author(s):  
W. Chiu ◽  
M.F. Schmid ◽  
T.-W. Jeng

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.


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

1980 ◽  
Vol 41 (C8) ◽  
pp. C8-586-C8-589
Author(s):  
M. Favre-Bonte ◽  
J. C. Joud ◽  
P. Hicter ◽  
P. Desre

1982 ◽  
Vol 43 (C9) ◽  
pp. C9-23-C9-29
Author(s):  
J. M. Dubois ◽  
P. Chieux ◽  
G. Le Caer ◽  
J. Schweitzer ◽  
J. Bletry

2020 ◽  
Vol 64 (1-4) ◽  
pp. 1495-1504
Author(s):  
Fangchao Xu ◽  
Yongquan Guo ◽  
Ran Zhou ◽  
Junjie Jin ◽  
Chuan Zhao ◽  
...  

To solve the problem of reduction of suspension force of permanent magnet system with variable magnetic flux path control, according to the structure of the system, suspension principle of the permanent magnet system with variable magnetic flux path control and the generation principle of the load torque, the influence of the mechanical structure of the system on the suspension force is analyzed by changing part of parameters of the system structure. The results show that the existence of magnetic isolation plate is the main reason for the decrease of suspension force, the permanent magnet ring can be thickened to 11.91 mm, the annular gap can be reduced to 1 mm, thickness of the “F” shaped magnetizer can be increased to 9 mm to increase the suspension force.


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