On the role of d orbitals in sulfur hexafluoride

1986 ◽  
Vol 108 (13) ◽  
pp. 3586-3593 ◽  
Author(s):  
Alan E. Reed ◽  
Frank. Weinhold
Keyword(s):  
Sulfur Hexafluoride ◽  
D Orbitals

scholarly journals Детерминизм локального атомного упорядочения в монослоях золота в формировании их электронной структуры

2022 ◽  
Vol 64 (3) ◽  
pp. 303
Author(s):  
В.Л. Карбовский ◽  
А.А. Романский ◽  
Л.И. Карбовская ◽  
В.В. Стонис
Keyword(s):  
Coordination Sphere ◽  
Electronic States ◽  
Mutual Arrangement ◽  
Quantum Mechanical ◽  
Quantum Mechanical Calculations ◽  
The Third ◽  
Long Range Interactions ◽  
Valence Bands ◽  
D Orbitals

The total and partial densities of electronic states of gold monolayer structures of different symmetry are calculated by the quantum mechanical calculations methods in the DFT approximation. It is shown that the first coordination sphere is determinant in the formation of the fine structure and the extent of the valence bands of the monolayer gold structures under study. The peaks splitting of the TDOS curve, which leads to its finer structure, is influenced not only by the lengths of interatomic bonds but also by the mutual arrangement of atoms. The influence of long-range interactions on the electronic structure of gold monolayers has been established. For example, for the (110) plane, a change in the atomic ordering in the third coordination sphere as a result of the introduction of a vacancy leads to noticeable changes in the TDOS curve, which indicates either a significant role of the atoms of the third coordination sphere or a significant redistribution of the interaction of d-orbitals of different symmetries of close neighbours. A correlation between the packing density, as well as the number of neighbours in the first coordination sphere, and the width of the energy band of gold monolayers has been established.

d Orbitals in the noble-gas dihalides

1970 ◽  
Vol 48 (17) ◽  
pp. 2695-2701 ◽  
Author(s):  
R. C. Catton ◽  
K. A. R. Mitchell
Keyword(s):  
Noble Gas ◽  
Valence Bond ◽  
Ionic Character ◽  
Orbital Exponent ◽  
Covalent Bonds ◽  
Model Calculations ◽  
Pair Bonds ◽  
Electron Repulsion Integrals ◽  
D Orbitals

Model calculations are reported for ArF2, KrF2, XeF2, ArCl2, KrCl2, and XeCl2. The approach is to compare the energies of a number of valence-bond structures for each molecule. The calculations use Slater-type radial functions and simplify the electron repulsion integrals with the Mulliken approximation. Energies are optimized by varying the d orbital exponent and a parameter which governs the ionic character of the covalent bonds. For all the molecules it is found that the structures such as (X—M+X− + X−M+—X) and X−M2+X−, which maintain the octet rule and exclude the use of d orbitals, are less stable than the structure X—M—X which implies localized electron-pair bonds based on pd hybrids at the noble-gas atom M.Approximate molecular wave functions are obtained from a configuration interaction calculation, and the general conclusion is that the valence-bond structures incorporating d orbitals become more important as the atomic number of the central atom increases. A preliminary study of the role of the [Formula: see text] orbital is also presented, but it seems this orbital contributes mainly as a polarization effect.

Role of cyclooxygenase inhibition and hyperoxia in regulating pulmonary perfusion in dogs

1995 ◽  
Vol 268 (4) ◽  
pp. H1521-H1530 ◽  
Author(s):  
L. L. Schulman ◽  
Y. Enson
Keyword(s):  
Sulfur Hexafluoride ◽  
Alveolar Ventilation ◽  
Pulmonary Perfusion ◽  
Cyclooxygenase Inhibition ◽  
Perivascular Inflammation ◽  
Hypoxic Vasoconstriction ◽  
Granulomatous Lung Disease ◽  
Low Tone ◽  
Diseased Lung

To assess the roles of cyclooxygenase inhibition and hyperoxia in regulating pulmonary perfusion, we studied 13 dogs with diffuse granulomatous lung disease (DGLD) and 13 normal dogs. Baseline observations were obtained at fractional inspired O2 (FIO2) 0.21 and 1.0 and repeated after infusion of meclofenamate (Mec; n = 8) or saline (n = 5). Resistance to flow was evaluated from the pulmonary end-diastolic gradient (PDG) and by ohmic pulmonary vascular resistance (PVR). Distribution of blood flow was evaluated with sulfur hexafluoride in DGLD and with multiple inert gas alveolar ventilation-perfusion (VA/Q) plots in normal dogs. Before infusion, there were no differences between the saline and Mec groups at either FIO2. Saline induced no significant changes at either FIO2. After Mec in DGLD, PDG at FIO2 0.21 rose from 4 +/- 2 to 6 +/- 4 mmHg (P < 0.04), PVR increased from 297 +/- 98 to 484 +/- 181 dyn.s.cm-5.m-2 (P < 0.01), whereas shunt flow (Qs/Qt) fell form 13.6 +/- 12.0 to 6.2 +/- 5.3% (P < 0.03). At FIO2 1.0 PDG rose from 3 +/- 2 to 4 +/- 3 mmHg (P < 0.02), PVR increased from 262 +/- 78 to 374 +/- 139 dyn.s.cm-5.m-2 (P < 0.01), whereas Qs/Qt fell from 14.5 +/- 13.3 to 6.4 +/- 5.2% (P < 0.02). After Mec in normal dogs, PDG at FIO2 0.21 rose from 3 +/- 1 to 4 +/- 1 mmHg (P < 0.015) and PVR increased from 256 +/- 92 to 340 +/- 101 dyn.s.cm-5.m-2 (P < 0.05); at FIO2 1.0 PDG and PVR were unchanged from preinfusion levels. In normal dogs, no parameters of VA/Q changed significantly with hyperoxia or Mec. These data suggest that perivascular inflammation enhances perfusion in DGLD by elaboration of vasodilator prostaglandins (PG). By inhibiting PG synthesis, Mec selectively increases resistance in diseased lung at FIO2 0.21 and lowers Qs/Qt. In contrast, there was vasoconstriction without flow redistribution in normal dogs, suggesting that vasodilator PGs contribute to the low tone in the normal pulmonary bed. The vasodilation without flow redistribution in both models during hyperoxia after Mec suggests an effect of O2 that is related neither to PG synthesis nor to hypoxic vasoconstriction.

THE ROLE OF RECOMBINANT LYSINE-PLASMINOGEN AND RECOMBINANT UROKINASE AND SULFUR HEXAFLUORIDE COMBINATION IN INDUCING POSTERIOR VITREOUS DETACHMENT

Retina ◽  
2004 ◽  
Vol 24 (2) ◽  
pp. 199-209 ◽  
Author(s):  
GAMZE MEN ◽  
GHOLAM A. PEYMAN ◽  
MAHMOUD GENAIDY ◽  
PO-CHENG KUO ◽  
FATEMAH GHAHRAMANI ◽  
...  
Keyword(s):  
Sulfur Hexafluoride ◽  
Posterior Vitreous Detachment ◽  
Vitreous Detachment

Ab initio study of the role of d orbitals in chlorosilane

1974 ◽  
Vol 96 (10) ◽  
pp. 3064-3070 ◽  
Author(s):  
James M. Howell ◽  
John R. Van Wazer
Keyword(s):  
Ab Initio ◽  
Ab Initio Study ◽  
D Orbitals
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