Medium range order and the radial distribution function

2006 ◽  
Vol 352 (2) ◽  
pp. 116-122 ◽  
Author(s):  
A. Bodapati ◽  
M.M.J. Treacy ◽  
M. Falk ◽  
J. Kieffer ◽  
P. Keblinski
2006 ◽  
Vol 14 (8-9) ◽  
pp. 888-892 ◽  
Author(s):  
Cang Fan ◽  
T.W. Wilson ◽  
W. Dmowski ◽  
H. Choo ◽  
J.W. Richardson ◽  
...  

2011 ◽  
Vol 1 (1) ◽  
Author(s):  
X. W. Fang ◽  
C. Z. Wang ◽  
S. G. Hao ◽  
M. J. Kramer ◽  
Y. X. Yao ◽  
...  

2013 ◽  
Vol 664 ◽  
pp. 614-619 ◽  
Author(s):  
Xue Lin ◽  
Cheng Guo Wang ◽  
Mei Jie Yu ◽  
Zhi Tao Lin ◽  
Shan Zhang

The local structure evolution of polyacrylonitrile (PAN) fibers during pre-oxidation and carbonization was studied using X-ray diffraction (XRD) and radial distribution function (RDF). The nearest inter-chains distance of PAN is 6.88 Å, which is close to the diameter of the “rigid rod” model proposed by Warner. The third neighbor distances of carbon fibers are greater than that of graphite, indicating the planar six-member rings are absent in the carbon fibers from 500 to 1250°C. The structure of fibers transforms from long-range order to long-range disorder during the pre-oxidation process, then transforms from short-range order to long-range order during the carbonization process.


Author(s):  
Jurica Novak ◽  
Maria A. Grishina ◽  
Vladimir A. Potemkin

: In this letter the newly introduced approach based on the radial distribution function (RDF) weighted by the number of va-lence shell electrons is applied for a series of HIV-1 protease enzyme and its complexes with inhibitors to evaluate the influ-ence of hydrogen atoms on the performance of the model. The multiple linear regression method was used for the selection of the relevant descriptors. Two groups of residues having dominant contribution to the RDF descriptor are identified as relevant for the inhibition. In the first group are residues like Arg8, Asp25, Thr26, Gly27 and Asp29, which establish direct interaction with the inhibitor, while the second group consists of the amino acids at the interface of the two homodimer sub-units or with the solvent. The crucial motif pointed out by our approach as the most important for inhibition of the enzyme’s activity and present in all inhibitors is hydroxyl group that establish hydrogen bond with Asp25 side chain. Additionally, the comparison to the model without hydrogen showed that both models are of similar quality, but the downside of the current model is the need for the determination of residues’ protonation states.


2010 ◽  
Vol 65 (1-2) ◽  
pp. 123-131 ◽  
Author(s):  
Oleksandr S. Roik ◽  
Oleksiy Samsonnikov ◽  
Volodymyr Kazimirov ◽  
Volodymyr Sokolskii

AbstractA local short-to-intermediate range order of liquid Al80Co10Ni10, Al72.5Co14.5Ni13, and Al65Co17.5Ni17.5 alloys was examined by X-ray diffraction and the reverse Monte Carlo modelling. The comprehensive analysis of three-dimensional models of the liquid ternary alloys was performed by means of the Voronoi-Delaunay method. The existence of a prepeak on the S(Q) function of the liquid alloys is caused by medium range ordering of 3d-transition metal atoms in dense-packed polytetrahedral clusters at temperatures close to the liquidus. The non-crystalline clusters, represented by aggregates of pentagons that consist of good tetrahedra, and chemical short-range order lead to the formation of the medium range order in the liquid binary Al-Ni, Al-Co and ternary Al-Ni-Co alloys.


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