Corrected Mulliken Charges for Small Molecules

A quantum mechanical correction is applied to the Mulliken atomic charges in order to fit them to the calculated dipole moment. This correction is obtained from the Charge - Charge flux - Overlap model (CCFO) for the interpretation of infrared intensities. Values of corrected Mulliken charges are calculated using different basis sets for the HF, H20, NH3, CH4, LiF, LiCI and NaCI molecules. The corrected charges are compared with atomic charges obtained from other partitioning schemes. Our results reveal that the corrected Mulliken charge shows an excellent numerical stability when the basis set becomes more extended. It also gives a better description of the charge separation in predominantly ionic molecules. Finally, the Mulliken charge seems to reflect more adequately intramolecular interactions when corrected as above

A review on the degradation of pollutants by fenton-like systems based on zero-valent iron and persulfate: Effects of reduction potentials, pH, and anions occurring in waste waters

Among the advanced oxidation processes (AOPs), the Fenton reaction has attracted much attention in recent years for the treatment of water and wastewater. This review provides insight into a particular variant of the process, where soluble Fe(II) salts are replaced by zero-valent iron (ZVI), and hydrogen peroxide (H(2)O(2)) is replaced by persulfate (S(2)O(8)(2−)). Heterogeneous Fenton with ZVI has the advantage of minimizing a major problem found with homogeneous Fenton. Indeed, the precipitation of Fe(III) at pH > 4 interferes with the recycling of Fe species and inhibits oxidation in homogeneous Fenton; in contrast, suspended ZVI as iron source is less sensitive to the increase of pH. Moreover, persulfate favors the production of sulfate radicals (SO(4)(•−)) that are more selective towards pollutant degradation, compared to the hydroxyl radicals ((•)OH) produced in classic, H(2)O(2)-based Fenton. Higher selectivity means that degradation of SO(4)(•−)-reactive contaminants is less affected by interfering agents typically found in wastewater; however, the ability of SO(4)(•)(−) to oxidize H(2)O/OH(−) to (•)OH makes it difficult to obtain conditions where SO(4)(•−) is the only reactive species. Research results have shown that ZVI-Fenton with persulfate works best at acidic pH, but it is often possible to get reasonable degradation at pH values that are not too far from neutrality. Moreover, inorganic ions that are very common in water and wastewater (Cl(−), HCO(3)(−), CO(3)(2−), NO(3)(−), NO(2)(−)) can sometimes inhibit degradation by scavenging SO(4)(•−) and/or (•)OH, but in other cases they even enhance the process. Therefore, ZVI-Fenton with persulfate might perform unexpectedly well in some saline waters, although the possible formation of harmful by-products upon oxidation of the anions cannot be ruled out

Análise da capacidade combinatória entre linhagens de girassol.

A capacidade geral (CGC) e a capacidade específica de combinação (CEC), entre duas linhagens macho-estéreis (mãe) e um grupo de sete linhagens S4 restauradoras de fertilidade (pai), foram estimadas para estudar o potencial desses materiais em programas de melhoramento de girassol (Helianthus annuus L.). O método IV de Griffing, adaptado para cruzamentos dialélicos parciais, foi usado na análise das combinações híbridas. Considerando a CGC para rendimento de aquênios e teor de óleo, os progenitores com maior potencial para o melhoramento foram CMS HA 302 (originária de uma população norte-americana) para ser usada como mãe, e as linhagens 89V2345)3382 e 89V2345)3311 (derivadas da população V2000, obtida por seleção sobre a população Issanka, originária da França) como pais nos cruzamentos. Para o rendimento de aquênios, os efeitos gênicos não aditivos foram importantes na determinação das diferenças entre progenitores. Considerando-se os efeitos gênicos aditivos e não-aditivos conjuntamente, as melhores combinações são CMS HA 302 x 89V2396)5333 para rendimento de aquênios e CMS HA 30379NW22 x 89V2345)3382 para teor de óleo e rendimento de óleo