The Valence Angle at the Bridge Oxygen Atom in Cellulose

1979 ◽  
Vol 12 (1) ◽  
pp. 152-153 ◽  
Author(s):  
P. R. Sundararajan
Keyword(s):  
Oxygen Atom ◽  
Valence Angle ◽  
Bridge Oxygen Atom ◽  
Bridge Oxygen

PARAMETERIZATION OF REAXFF POTENTIAL OF MG/AL/SI/O INTERACTION AND INVESTIGATION OF MECHANICAL PROPERTIES FOR S-GLASS

2021 ◽  
Author(s):  
JEJOON YEON ◽  
SANJIB C. CHOWDHURY ◽  
CHAITANYA M. DAKSHA ◽  
DONATO BELMONTE ◽  
ADRI VAN DUIN ◽  
...  
Keyword(s):  
Progressive Failure ◽  
Valence Angle ◽  
Glass Structure ◽  
Bond Distance ◽  
Heat Of Formation ◽  
Value Analysis ◽  
Structure And Property ◽  
Static Modulus ◽  
Fracture Formation ◽  
Bridge Oxygen

New ReaxFF parameters are developed for the description of Mg/Al/Si/O interaction for the Magnesium Aluminosilicate (MAS) glass structure. The training set contains energy curves from equation of state for various Mg/Al/Si/O crystals, valence angle and bond distance scan, and heat of formation for the Mg/Al/Si/O interactions. A semi-automated Genetic Algorithm assisted by Artificial Neural Network is applied for this parametrization. Validation efforts showed the current ReaxFF parameter set can describe the atomistic structure and property of tectosilicate MAS glass including S-glass. Estimated quasi-static modulus of S-glass structure matches well with experimental value. Analysis shows the key of high modulus of S-glass is numerous Mg-BO (Bridge Oxygen) interactions across the Mg-O-AlSi structure. In addition, atomistic origin of high ductility and progressive failure of S-glass is derived from the reconstruction of the atomic structure, forming Mg-BO-Si interactions that delays fracture formation.

A study of twinning in YBa2Cu3O7−x by large-angle convergent-beam electron diffraction

1990 ◽  
Vol 48 (4) ◽  
pp. 20-21
Author(s):  
P.A. Midgley ◽  
R. Vincent ◽  
D. Cherns
Keyword(s):  
Electron Diffraction ◽  
Oxygen Atom ◽  
Strain Field ◽  
Large Angle ◽  
Convergent Beam Electron Diffraction ◽  
Orthorhombic Distortion ◽  
Beam Electron ◽  
Resultant Powder ◽  
Convergent Beam ◽  
Mesh Grid

The oxygenation of YBa2Cu3O7−x (YBCO) leads to an orthorhombic distortion of the unit cell to accommodate the extra oxygen atom. This makes the formation of twins energetically favourable with CuO4 planar unit chains running alternately along the a and b axes of the parent tetragonal structure. The geometry of this twinning is such that four possible twin variants may co-exist with the twin boundaries lying in the (110) or (110) planes of the deformed structure. The traces of these planes are not mutually perpendicular and thus the crystal is strained to allow for the mismatch. It is to the nature of this strain field that this work has been addressed.Sintered samples were prepared by crushing and dispersing the resultant powder onto a very fine Cu mesh grid. Single crystals were chemically thinned to perforation. No discernible artefacts were seen and similar results were obtained with either method.

Fast oxygen atom facility for studies related to low earth orbit activities

1992 ◽  
Author(s):  
G. CALEDONIA ◽  
R. KRECH ◽  
B. UPSCHULTE ◽  
D. SONNENFROH ◽  
D. OAKES ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Low Earth Orbit ◽  
Earth Orbit

Theoretical Studies of High Energy Oxygen Atom Chemistry

2004 ◽  
Author(s):  
M. Braunstein ◽  
J. Duff ◽  
R. Shroll ◽  
L. Bernstein ◽  
S. Adler-Golden
Keyword(s):  
Oxygen Atom ◽  
High Energy ◽  
Theoretical Studies ◽  
Atom Chemistry

Conformation and electronic structure of aromatic chloroformates

1987 ◽  
Vol 52 (4) ◽  
pp. 970-979 ◽  
Author(s):  
Otto Exner ◽  
Pavel Fiedler
Keyword(s):  
Electronic Structure ◽  
Oxygen Atom ◽  
Strong Interaction ◽  
Electron Distribution ◽  
Room Temperature ◽  
Functional Group ◽  
Dipole Moments ◽  
Carbonyl Oxygen ◽  
Nonpolar Solvents ◽  
Single Method

Aromatic chloroformates Ib-Ie were shown to exist in the ap conformation, in agreement with aliphatic chloroformates, i.e. the alkyl group is situated cis to the carbonyl oxygen atom as it is the case in all esters. While 4-nitrophenyl chloroformate (Ie) is in this conformation in crystal, in solution at most several tenths of percent of the sp conformation may be populated at room temperature and in nonpolar solvents only. A new analysis of dipole moments explained the previous puzzling results and demonstrated the impossibility to determine the conformation by this single method, in consequence of the strong interaction of adjoining bonds. If, however, the ap conformation is once proven, the dipole moments reveal some features of the electron distribution on the functional group, characterized by the enhanced polarity of the C-Cl bond and reduced polarity of the C=O bond. This is in agreement with the observed bond lengths and angles.

scholarly journals Oxygen Atom Transfer Catalysis by Dioxidomolybdenum(VI) Complexes of Pyridyl Aminophenolate Ligands

Polyhedron ◽  
2021 ◽  
pp. 115234
Author(s):  
Md. Kamal Hossain ◽  
Jörg A. Schachner ◽  
Matti Haukka ◽  
Michael G. Richmond ◽  
Nadia C. Mösch-Zanetti ◽  
...  
Keyword(s):  
Oxygen Atom ◽  
Atom Transfer ◽  
Oxygen Atom Transfer

Nonclassical oxygen atom transfer reactions of an eight-coordinate dioxomolybdenum(vi) complex

2021 ◽  
Author(s):  
Leila G. Ranis ◽  
Jacqueline Gianino ◽  
Justin M. Hoffman ◽  
Seth N. Brown
Keyword(s):  
Oxygen Atom ◽  
Transfer Reaction ◽  
Transfer Reactions ◽  
Atom Transfer ◽  
Oxygen Atom Transfer ◽  
Oxygen Atom Transfer Reactions ◽  
Atom Transfer Reactions ◽  
Oxygen Atoms

Eight-coordinate MoO2(DOPOQ)2 can donate two oxygen atoms to substrates such as phosphines in a four-electron nonclassical oxygen atom transfer reaction.

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