Search results for "Valence"
showing 10 items of 2732 documents
Prevalence of the patients with history of hepatitis in a dental faculty
2006
Objectives: The aim of the study is to investigate the prevalence of the dental patients who had a history of hepatitis. Study design: A total of 13.527 records of patients who were examined between October 1, 2002 and October 1, 2004 were reviewed retrospectively. The medical histories of patients were taken before routine clinical and radiographic examination. A dental software program was used for the collection of data. The chi-square test was utilized to evaluate correlations between different parameters. Results: The percentage of the patients who had a medical history of hepatitis was 7.9% (n=1065). Within the total patients; history of hepatitis A was found as 3.2% (n=438), hepatiti…
Epidemiology of Nonalcoholic Fatty Liver Disease and Nonalcoholic Steatohepatitis: Implications for Liver Transplantation.
2018
Nonalcoholic fatty liver disease (NAFLD) affects 25% of the global adult population with a range of 13.5% in Africa and 31.8% in the Middle East. Nonalcoholic fatty liver disease is closely associated with a constellation of metabolic comorbidities which include: obesity, type 2 diabetes mellitus, hypertension, and hypercholesteremia. In fact, the increasing number of metabolic comorbidities not only increases the prevalence of NAFLD but also places patients at higher risk for progressive liver disease. As such, NAFLD is presently among the top etiologies for hepatocellular carcinoma and an indication for liver transplantation (LT) in the United States. Therefore, the following recommendati…
Electronic structure and properties of MAu and MOH, where M = Tl and Nh: New data
2018
Abstract Properties of the MAu and MOH (M = Tl and element 113, Nh) molecules were calculated using the 2c-DFT method. The obtained data are needed for evaluation of reactivity of Nh studied by gas-phase chromatography experiments. Results show that Nh should be less reactive (or more volatile) than Tl, both with respect to gold and the hydroxyl group. The reason for that are strong relativistic effects on the valence 7s and 7p electron shells. In difference to the atoms, NhOH may be less volatile than TlOH due to its larger both dipole moment and anisotropic polarizability.
Reactivity of the Superheavy Element 115, Mc, and Its Lighter Homologue, Bi, with Respect to Gold and Hydroxylated Quartz Surfaces from Periodic Rela…
2021
Adsorption energies (Eads) of the superheavy element (SHE) Mc, its lighter homologue (Bi), as well as of another superheavy element Nh and some lighter homologues of SHEs on gold and hydroxylated quartz surfaces are predicted via periodic relativistic density functional theory calculations. The aim of this study is to support "one-atom-at-a-time" gas-phase chromatography experiments that are examining the reactivity and volatility of Mc. The obtained Eads values of the Bi and Mc atoms on the Au(111) surface are >200 kJ/mol. On the hydroxylated quartz surface, Mc should adsorb with a minimal energy of 58 kJ/mol. On both types of surfaces, Eads(Mc) should be ∼100 kJ/mol smaller than Eads(Bi) …
Ab initio calculations of the transfer parameters and coulombic repulsion and estimation of their effects on the electron delocalization and magnetic…
2003
International audience; In this work, we present ab initio calculations on embedded fragments that permit to extract the value of the effective electron transfer integral and coulombic repulsion between W nearest neighbour atoms in a mixed-valence αPW12O40 Keggin polyoxoanion. This allows us to perform a quantitative study of the influence of these two parameters on the magnetic properties of Keggin polyoxoanions reduced by two electrons. We surprisingly find that the electron transfer between edge-sharing and corner-sharing WO6 octahedra have very close values, and show that the punctual charges estimation of coulombic repulsion may not be accurate enough to study the electronic distributi…
Six-coordinate [CoIII(L)2]z (z = 1−, 0, 1+) complexes of an azo-appended o-aminophenolate in amidate(2−) and iminosemiquinonate π-radical (1−) redox-…
2018
Aerobic reaction of the ligand H2L1, 2-(2-phenylazo)-anilino-4,6-di-tert-butylphenol, CoCl2·6H2O and Et3N in MeOH under refluxing conditions produces, after work-up and recrystallization, black crystals of [Co(L1)2] (1). When examined by cyclic voltammetry, 1 displays in CH2Cl2 three one-electron redox responses: two oxidative, E11/2 = 0.30 V (peak-to-peak separation, ΔEp = 100 mV) and E21/2 = 1.04 V (ΔEp = 120 mV), and one reductive E1/2 = −0.27 V (ΔEp = 120 mV) vs. SCE. Consequently, 1 is chemically oxidized by 1 equiv. of [FeIII(η5-C5H5)2][PF6], affording the isolation of deep purple crystals of [Co(L1)2][PF6]·2CH2Cl2 (2), and one-electron reduction with [CoII(η5-C5H5)2] yielded bluish-b…
Electron Delocalization and Electrostatic Repulsion at the Origin of the Strong Spin Coupling in Mixed-Valence Keggin Polyoxometalates: Ab Initio Cal…
2004
International audience; Cet article détaille une procédure générale qui associe l′évaluation de paramètres microscopiques et la prédiction de propriétés macroscopiques. Les principales interactions entre les électrons délocalisés sur des polyoxométalates à valence mixte sont extraites à partir du calcul de la spectroscopie de valence de fragments immergés dans un bain qui reproduit les principaux effets du reste du cristal sur le fragment considéré. Nous avons extrait non seulement la valeur du transfert électronique, du couplage magnétique et du paramètre de "exchange-transfer" entre ions métalliques premiers et seconds voisins, mais encore la valeur de la répulsion électrostatique entre l…
[CuII{(LISQ)˙−}2] (H2L: thioether-appended o-aminophenol ligand) monocation triggers change in donor site from N2O2 to N2O(2)S and valence-tautomerism
2019
Using a potentially tridentate o-aminophenol-based redox-active ligand H2L1 (2-[2-(benzylthio)phenylamino]-4,6-di-tert-butylphenol) in its deprotonated form, [Cu(L1)2] has been synthesized and crystallized as [CuII(L1)2]·CH2Cl2 (1·CH2Cl2). A cyclic voltammetry experiment (in CH2Cl2; V vs. SCE (saturated calomel electrode)) on 1·CH2Cl2 exhibits two oxidative (E = 0.20 V (peak-to-peak separation, ΔEp = 100 mV) and E = 0.90 V (ΔEp = 140 mV)) and two reductive (E = -0.52 V (ΔEp = 110 mV) and E = -0.92 V (ΔEp = 120 mV)) responses. Upon oxidation using a stoichiometric amount of [FeIII(η5-C5H5)2](PF6), 1·CH2Cl2 yielded [Cu(L1)2](PF6) (2). Structural analysis (100 K) reveals that 1·CH2Cl2 is a fou…
Role of the electron transfer and magnetic exchange interactions in the magnetic properties of mixed-valence polyoxovanadate complexes.
2008
International audience; Modeling the properties of high-nuclearity, high-electron-population, mixed-valence (MV) magnetic systems remains one of the open challenges in molecular magnetism. In this work, we analyze the magnetic properties of a series of polyoxovananadate clusters of formula [V 18O 42] (12-) and [V 18O 42] (4-). The first compound is a fully localized spin cluster that contains 18 unpaired electrons located at the metal sites, while the second one is a MV cluster with 10 unpaired electrons largely delocalized over the 18 metal sites. A theoretical model that takes into account the interplay between electron transfer and magnetic exchange interactions is developed to explain t…
New light on an old debate: does the RCN–PtCl2 bond include any back-donation? RCN←PtCl2 backbonding vs. the IR νCN blue-shift dichotomy in organoni…
2019
For a series of organonitrile [RCN (R = Me, CF3, Ph, CH3Ph, CF3Ph)] ligands, the nature of the N–Pt bond in the related cis-/trans-(RCN)2PtCl2 complexes has been computationally investigated by Density Functional Theory. A fragment based bond analysis has been performed in the canonical Kohn–Sham molecular orbitals framework, and it has been ultimately assessed that this bond is characterized both by N→Pt σ and by N←Pt π contributions. Voronoi Deformation Density charges further confirms the occurrence of N←Pt π interactions. Moreover, the Energy Decomposition Analysis-Natural Orbital for Chemical Valence (EDA-NOCV) method shows that the strength of the N←Pt π interaction is not negligible …