Aromaticity reversals between the electronic ground (S0) and low-lying singlet (S1, S2) and triplet (T1, T2, T3) states of naphthalene and anthracene are investigated by calculating the respective off-nucleus isotropic magnetic shielding distributions using complete-active-space self-consistent field (CASSCF) wavefunctions involving gauge-including atomic orbitals (GIAOs). The shielding distributions around the aromatic S0, antiaromatic S1 (1Lb), and aromatic S2 (1La) states in naphthalene are found to resemble the outcomes of fusing together the respective S0, S1, and S2 shielding distributions of two benzene rings. In anthracene, 1La is lower in energy than 1Lb, and as a result, the S1 state becomes aromatic, and the S2 state becomes antiaromatic; the corresponding shielding distributions are found to resemble extensions by one ring of those around the S2 and S1 states in naphthalene. The lowest antiaromatic singlet state of either molecule is found to be significantly more antiaromatic than the respective T1 state, which shows that it would be incorrect to assume that the similarity between the (anti)aromaticities of the S1 and T1 states in benzene, cyclobutadiene, and cyclooctatetraene would be maintained in polycyclic aromatic hydrocarbons.
Charge transfer complex formation method has been applied for the spectrophotometric determination of erythromycin ethylsuccinate, in bulk sample and dosage form. The method was accurate, simple, rapid, inexpensive and sensitive depending on the formed charge- transfer complex between cited drug and, 2,3- Dichloro-5,6-dicyano-p- benzoquinone (DDQ) as a chromogenic reagent. The formed complex shows absorbance maxima at 587 nm against reagent blank. The calibration graph is linear in the ranges of (10 - 110) μg.mL-1 with detection limit of 0.351μg.mL-1. The results show the absence of interferences from the excipients on the determination of the drug. Therefore the proposed method has been successfully applied for the determination of eryth
... Show MoreThis contribution provides an atomistic understanding into the impact of W, Nb, and Mo co-substitution at Hf-site of cubic HfO2 lattice to produce Hf1−xTMxO2 system at x = 25%. The calculations have been performed under the framework of density functional theory supported by Habbured parameter (DFT+U). Structural analysis demonstrates that the recorded lattice constants is in good coherence with the previously published results. For the lattice parameters, contraction by 1.33% comparing with the host system has been reported. Furthermore, the doping effect of TM on the band gap leads to its reduction in the resulting Hf0.75TM0.25O2 configurations. The partial density of states (PDOS) indicate that hybridization through localized electroni
... Show MoreBackground. Dental implantation has become a standard procedure with high success rates, relying on achieving osseointegration between the implant surface and surrounding bone tissue. Polyether ether ketone (PEEK) is a promising alternative to traditional dental implant materials like titanium, but its osseointegration capabilities are limited due to its hydrophobic nature and reduced surface roughness. Objective. The aim of the study is to increase the surface roughness and hydrophilicity of PEEK by treating the surface with piranha solution and then coating the surface with epigallocatechin-3-gallate (EGCG) by electrospraying technique. Materials and Methods. The study includes four groups intended to investigate the effect of pir
... Show MoreThe influence of the reaction gas composition during the DC magnetron sputtering process on the structural, chemical and optical properties of Ce-oxide thin films was investigated. X-ray diffraction (XRD) studies confirmed that all thin films exhibited a polycrystalline character with cubic fluorite structure for cerium dioxide. X-ray photoelectron spectroscopy (XPS) analyses revealed that cerium is present in two oxidation states, namely as CeO2 and Ce2O3, at the surface of the films prepared at oxygen/argon flow ratios between 0% and 7%, whereas the films are completely oxidized into CeO2 as the aforementioned ratio increases beyond 14%. Various optical parameters for the thin films (including an optical band gap in the range of 2.25–3.
... Show MoreThe present work investigates the effect of magneto – hydrodynamic (MHD) laminar natural convection flow on a vertical cylinder in presence of heat generation and radiation. The governing equations which used are Continuity, Momentum and Energy equations. These equations are transformed to dimensionless equations using Vorticity-Stream Function method and the resulting nonlinear system
of partial differential equations are then solved numerically using finite difference approximation. A thermal boundary condition of a constant wall temperature is considered. A computer program (Fortran 90) was built to calculate the rate of heat transfer in terms of local Nusselt number, total mean Nusselt number, velocity distribution as well as te
This study presents a linguistic analysis of how Russian and American mainstream media and official statements deployed speech acts of accusation during the 2022 Russian invasion of Ukraine. Using Speech Act Theory (Austin, 1962; Searle, 1976) as the framework. The study analyzes 50 texts of English-language official statements and media headlines from both sides. In this research utterances are categorized into assertives, expressives, directives, commissives, and declarations, and analyzes their pragmatic force in shaping narratives. The analysis reveals contrasts in tone and rhetorical strategy: U.S. officials and media overwhelmingly use assertive accusations and expressive condemnations to morally indict Russia, while Russian counterpa
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