First-Principles Study of Optical Absorption Energies, Ligand Field and Spin-Hamiltonian Parameters of Cr³⁺ Ions in Emeralds

Herein, we study the electronic structure, energies, and vibronic structure of optical d-d transitions of Cr3+ ions doped in beryl (Be3Si6Al2O18:Cr3+, emerald). A computational protocol is developed that combines periodic density functional theory (for modeling of the bulk crystalline lattice of emerald) and the multireference configuration interaction complete active space self-consistent field method supplemented with n-electron valence second-order perturbation theory (for the calculation of the energy levels, wave functions, and spin-Hamiltonian and ligand-field parameters of the trigonal Cr3+ centers in the [CrO6]9– clusters embedded in an extended point charge field). Ligand-field parameters were extracted from mapping the effective ligand-field Hamiltonian onto the full many-particle Hamiltonian from one side and from a direct fit to energies of computed d-d transitions on the other side. These have been analyzed using ab initio ligand-field theory. The quality of the theoretical predictions is critically assessed through a detailed comparison with the available experimental data

Poluarea mediului riveran pe cursul superior al râului Tazlăul Sărat

The paper presents an analysis of the pollution phenomenon in the Tazlăul Sărat River basin. The studies and researches were carried out on the upper course of the river, in the area of Zemeş locality, where there are a series of wells for oil extraction. The floods have morphologically altered the minor river bed, which has influenced the stability of the banks and river basins. Crude oil pipelines are located in the river bank. Field research has analyzed the river sector between "Toderaş" and "Canton of Maxim", which administratively belongs to the commune of Zemeş, Bacău County. The flood of June 2016 had an excessive impact on the stability of oil pipelines, a situation that caused the scrapping and suspension of the pipeline

Studii şi cercetări privind poluarea mediului de către depozitele de deşeuri industriale

The Moldovan area has a large number of industrial waste deposits containing mine waste, slag, ash, technological waste etc. The presence of the deposit causes the air, soil, subsoil, surface and underground waters, flora and fauna and the mental state of the people to be polluted. The case study made at a landfill site highlights the multiple forms of induced pollution and their serious consequences on the environment. The deposit consists of a mixture of slag, foundry residues,industrial liquids, etc., which are extremely aggressive in air, soil, surface and underground waters. Physical and chemical indicators analyzed for soil in the area adjacent to the landfill were pH, Cd (cadmium), Mn (manganese), P (lead), SO4 (sulphate),etc. The pollution phenomenon affects all forms of environment in a serious form and the impact is indefinite

Influence of Titanium Additions on The Electrochemical Behaviour of NiCr/Ti Laser Cladded Coatings

In this research, the electrochemical evaluation of NiCr/Ti laser cladded coatings in simulated polymer electrolyte membrane fuel cells (PEMFCs) environment was investigated. The Laser Cladding technique was used to develop protective coatings on mild steel substrate using NiCr-based powders mixed with 12.5, 15, 17.5 and 20 wt.% Ti additions. The samples were tested at room temperature in Na2SO4 0.1M + 0.1 ppm F-. The potentiodynamic polarization curves are presented before and after the samples were subjected to accelerated stress tests, for 6 hours each, at +0.736 V (cathodic environment) and at -0.493 V (anodic environment). Afterwards, scanning electron microscopy (SEM) was used to investigate the effect of Ti addition in terms of morphology. Energy-dispersive X-ray spectroscopy (EDS) was performed for chemical evaluation of the surface after corrosion tests

Potential Risks of Excess Iodine Ingestion and Exposure: Statement by the American Thyroid Association Public Health Committee

Peer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/140261/1/thy.2014.0331.pd

Social assistance performance in Central and Eastern Europe: A pre-transfer post-transfer comparison

The anti-poverty impact of national social assistance programmes in eight Central and Eastern European countries is examined using data from the European Union-Survey of Income and Living Conditions (EU-SILC). Results indicate that social assistance programmes achieve only limited poverty reduction, while spending a significant amount of their resources on the non-poor. The more extensive and generous programmes achieve higher effectiveness in reducing poverty. Efficiency on the other hand appears to be linked only to programme size and not to benefit levels. Unlike Western Europe, no trade-off between effectiveness and efficiency could be detected