scholarly journals On Ve-Degree-Based Irregularity Properties of the Crystallographic Structure of Molecules

2021 ◽  
Vol 2021 ◽  
pp. 1-22
Author(s):  
Akbar Jahanbani ◽  
Rana Khoeilar ◽  
Hajar Shooshtari
Keyword(s):  
Molecular Structure ◽  
Complex Network ◽  
Topological Structure ◽  
Organic Molecules ◽  
Crystallographic Structure ◽  
Quantitative Characterization ◽  
Material Engineering ◽  
Structure Of Molecules ◽  
Crystallographic Structures

Irregularity indices are usually used for quantitative characterization of the topological structure of nonregular graphs. In numerous applications and problems in material engineering and chemistry, it is useful to be aware that how irregular a molecular structure is? In this paper, we are interested in formulating closed forms of irregularity measures of some of the crystallographic structures of Cu 2 O p , q , r and crystallographic structure of titanium difluoride of T i F 2 p , q , r . These theoretical conclusions provide practical guiding significance for pharmaceutical engineering and complex network and quantify the degree of folding of long organic molecules.

scholarly journals On Irregularity Measures of Some Dendrimers Structures

Mathematics ◽  
2019 ◽  
Vol 7 (3) ◽  
pp. 271 ◽  
Author(s):  
Wei Gao ◽  
Muhammad Aamir ◽  
Zahid Iqbal ◽  
Muhammad Ishaq ◽  
Adnan Aslam
Keyword(s):  
Molecular Structure ◽  
Topological Structure ◽  
Enthalpy Of Vaporization ◽  
Regular Graphs ◽  
Quantitative Characterization ◽  
Molecular Graphs ◽  
Irregularity Index ◽  
Boiling Points ◽  
Vertex Degrees

A graph is said to be a regular graph if all its vertices have the same degree, otherwise, it is irregular. Irregularity indices are usually used for quantitative characterization of the topological structure of non-regular graphs. In numerous applications and problems in material engineering and chemistry, it is useful to be aware that how irregular a molecular structure is? Furthermore, evaluations of the irregularity of underline molecular graphs could be valuable for QSAR/QSPR studies, and for the expressive determines of chemical and physical properties, such as enthalpy of vaporization, toxicity, resistance, Entropy, melting and boiling points. In this paper, we think over the following four irregularity measures: the irregularity index by Albertson, σ irregularity index, the total irregularity index and the variance of vertex degrees. By way of graph structural estimation and derivations, we determine these irregularity measures of the molecular graphs of different classes of dendrimers.

scholarly journals Characterization of Symmetry of Complex Networks

Symmetry ◽  
2019 ◽  
Vol 11 (5) ◽  
pp. 692
Author(s):  
Yangyang Chen ◽  
Yi Zhao ◽  
Xinyu Han
Keyword(s):  
Automorphism Group ◽  
Complex Networks ◽  
Complex Network ◽  
Real World ◽  
Symmetry Property ◽  
Global Symmetry ◽  
Quantitative Characterization ◽  
Natural Action ◽  
Vertex Set

Recently, symmetry in complex network structures has attracted some research interest. One of the fascinating problems is to give measures of the extent to which the network is symmetric. In this paper, based on the natural action of the automorphism group Aut ( Γ ) of Γ on the vertex set V of a given network Γ = Γ ( V , E ) , we propose three indexes for the characterization of the global symmetry of complex networks. Using these indexes, one can get a quantitative characterization of how symmetric a network is and can compare the symmetry property of different networks. Moreover, we compare these indexes to some existing ones in the literature and apply these indexes to real-world networks, concluding that real-world networks are far from vertex symmetric ones.

Biochemical and Crystallographic Characterization of Homologous Non-peptidic Thrombin Inhibitors Having Alternate Binding Modes

1998 ◽  
Vol 54 (6) ◽  
pp. 1207-1215
Author(s):  
Corey L. Strickland ◽  
John. M. Fevig ◽  
Robert A. Galemmo ◽  
Brian L. Wells ◽  
Charles A. Kettner ◽  
...  
Keyword(s):  
Aromatic Ring ◽  
Thrombin Inhibitors ◽  
Side Chain ◽  
Crystallographic Structure ◽  
Binding Modes ◽  
Tetrahedral Geometry ◽  
Ligand Affinity ◽  
Covalently Bonded ◽  
Crystallographic Structures

The X-ray crystallographic structure of [N-(3-phenylpropionyl)-N-(phenethyl)]-Gly-boroLys-OH (HPBK, Ki  = 0.42 nM, crystallographic R factor to 1.8 Å resolution, 19.6%) complexed with human α-thrombin shows that the boron adopts a tetrahedral geometry and is covalently bonded to the active serine, Ser195. The HPBK phenethyl aromatic ring forms an edge-to-face interaction with the indole side chain of Trp215. Four HPBK analogs containing either electron-withdrawing or electron-donating substitutents at the 3′ position of the phenethyl ring were synthesized in an attempt to modulate ligand affinity by inductive stabilization of the edge-to-face interaction. Refined crystallographic structures of the trifluoromethyl (Ki = 0.37 nM, crystallographic R factor to 2.0 Å resolution = 18.7%), fluoro (Ki = 0.60; R factor to 2.3 Å resolution = 18.4%), methoxy (Ki = 0.91 nM, R factor to 2.2 Å resolution = 19.8%) and methyl (Ki = 0.20 nM, R factor to 2.5 Å resolution = 16.9%) HPBK analogs complexed with thrombin revealed two binding modes for the closely related com-pounds. A less than 1.5-fold variation in affinity was observed for analogs (trifluoromethyl-HPBK and fluoro-HPBK) binding with the edge-to-face interaction. The slight inductive modulation is consistent with the overall weak nature of the edge-to-face interaction. Owing to an unexpected rotation of the phenethyl aromatic ring, the 3′ substituent of two analogs, methoxy-HPBK and methyl-HPBK, made direct contact with the Trp215 indole side chain. Increased affinity of the 3′ methyl analog is attributed to favorable interactions between the methyl group and the Trp215 indole ring. Differences in inhibitor, thrombin and solvent structure are discussed in detail. These results demonstrate the subtle interplay of weak forces that determine the equilibrium binding orientation of inhibitor, solvent and protein.

High Resolution Replication of Organoclay Surfaces

1982 ◽  
Vol 40 ◽  
pp. 576-577
Author(s):  
W. W. Barker ◽  
W. E. Rigsby ◽  
V. J. Hurst ◽  
W. J. Humphreys
Keyword(s):  
Clay Mineral ◽  
Organic Molecule ◽  
Organic Molecules ◽  
X Ray Diffraction ◽  
Xrd Pattern ◽  
X Ray ◽  
Naturally Occurring ◽  
Silicate Layers ◽  
Mineral Identification

Experimental clay mineral-organic molecule complexes long have been known and some of them have been extensively studied by X-ray diffraction methods. The organic molecules are adsorbed onto the surfaces of the clay minerals, or intercalated between the silicate layers. Natural organo-clays also are widely recognized but generally have not been well characterized. Widely used techniques for clay mineral identification involve treatment of the sample with H2 O2 or other oxidant to destroy any associated organics. This generally simplifies and intensifies the XRD pattern of the clay residue, but helps little with the characterization of the original organoclay. Adequate techniques for the direct observation of synthetic and naturally occurring organoclays are yet to be developed.

Microstructural characterization of CoPtCr/Cr thin film disks by cross-section TEM and elongated probe micro-diffraction

1991 ◽  
Vol 49 ◽  
pp. 762-763
Author(s):  
M.A. Parker ◽  
K.E. Johnson ◽  
C. Hwang ◽  
A. Bermea
Keyword(s):  
Magnetic Recording ◽  
Electron Probe ◽  
Microstructural Characterization ◽  
Crystallographic Structure ◽  
Recording Media ◽  
Layer By Layer ◽  
Cross Sectional ◽  
New Techniques ◽  
Polished Side

We have reported the dependence of the magnetic and recording properties of CoPtCr recording media on the thickness of the Cr underlayer. It was inferred from XRD data that grain-to-grain epitaxy of the Cr with the CoPtCr was responsible for the interaction observed between these layers. However, no cross-sectional TEM (XTEM) work was performed to confirm this inference. In this paper, we report the application of new techniques for preparing XTEM specimens from actual magnetic recording disks, and for layer-by-layer micro-diffraction with an electron probe elongated parallel to the surface of the deposited structure which elucidate the effect of the crystallographic structure of the Cr on that of the CoPtCr.XTEM specimens were prepared from magnetic recording disks by modifying a technique used to prepare semiconductor specimens. After 3mm disks were prepared per the standard XTEM procedure, these disks were then lapped using a tripod polishing device. A grid with a single 1mmx2mm hole was then glued with M-bond 610 to the polished side of the disk.

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