This paper reconstructs the relative sea level changes during the Holocene on the southeastern Brazilian coastal region (Armação dos Búzios city, at north of Rio de Janeiro state), based on the presence of rocky bottom worm snails, Vermetidae (Mollusca: Gastropoda) as bioindicators. Chronology was established by radiocarbon Accelerator Mass Spectrometry technique. Three evolutionary stages of sea level were established: sea-level lower than the current one between 8,148-6,300 cal yr BP, a rising of sea level between 6,300-4,500 cal yr BP, with a transgressive maximum of about 2.4 m above the present level at 4,700-4,500 cal yr BP, and a sea level drop from 4,500 cal yr BP until the present.

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The emission of carbon dioxide in large amounts is commonly believed to be the main cause of global climate changes. Development of CO 2 capture processes is still a big current challenge. Some anions have been studied for the gas sequestration process due their great affinity to CO 2 . In this work, electronic structure calculations were performed at the MP2/aug-cc-pvtz level to compute the interaction between 20 anions and CO 2 . A CBS scheme, using extrapolated energies, was also employed for both gas phase and solvent calculations. The reactions between the anions and CO 2 were therefore studied in four different conditions (gas phase, toluene, tetrahydrofuran and water). The trends observed for the reaction thermodynamics with the MP2 method is similar to that observed previously with the B3LYP-D3 and M06-2X functionals. The reactions in the gas phase are highly exothermic and do not involve any activation energy. The solvent effect reduces the exothermicity and induces an intrinsic activation barrier. The negative charge is dispersed in the adduct, leading to a weaker interaction in a polar solvent. Then, increasing the medium polarity, the energy difference between the adduct and the reactants decreases. We also observed a limit for solvent stabilization in the low dielectric constant range. For example, the results obtained with tetrahydrofuran are closer to those obtained with water than to those obtained with toluene. Considering both the thermodynamics of the reaction and the differential solvent effects, we were able to indicate anions derived from alkyl sulfides as the most convenient for CO 2 sequestration among the set here considered.

Density functional theory (DFT) (B3LYP/6-311++G(d,p)) calculations of the interacting strength 1,2-dithiolene anionic ligands with the [M(OH 2 ) 4 ] 2+ and [M(OH 2 ) 2 ] 2+ complexes (M = Ni and Zn) were performed. Three series of ligands were studied: compounds with an aromatic ring, with an ethylene moiety and with a heterocyclic ring. The ligands have substituents electron donors and acceptors by induction and resonance. Two substitution reactions were studied: the first is the substitution of two water molecules from the [M(OH 2 ) 6 ] 2+ by a dithiolene anionic ligand (L 2− ) and the second is the substitution of two water molecules from the [M(OH 2 ) 4 L] by another dithiolene anionic ligand. Geometric, electronic and energetic properties of the substituted aquacations are correlated with the metal-ligand affinity. All the substitution processes for both metal cations are spontaneous and are modulated by the electronic effect of each substituent of the ligand. Geometric parameters and chelation angle are correlated with the interaction strength. The energy decomposition analysis (EDA) results show that the electrostatic component is the main stabilizing term for the monosubstituted complexes, while for the disubstituted complexes the covalent term is the main stabilizing component. The polarization term is the main one to describe the covalent character. Natural bond orbital (NBO) shows the acid-base interaction nature of the metal-ligand bond.DFT Study of the Interaction between the Ni 2+ and Zn 2+ Metal Cations and the 1,2-Dithiolene Ligands J. Braz. Chem. Soc. 1162

Estudo teórico da relação dos orbitais de fronteira com eficiência de inibição de compostos modelo de derivados da 2-Aminopirazina Theoretical study of the relationship of border orbitals with compound inhibition efficiency model of derivatives from 2-Aminopirazine