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    The importance of evaluating the real metal concentration in nanoparticles post-synthesis for their applications: A case-study using silver nanoparticles
    (Elsevier Science Bv, 2016) Galazzi, Rodrigo Moretto; Santos, Elias de Barros [UNIFESP]; Caurin, Tatiana; Pessoa, Gustavo de Souza; Mazali, Italo Odone; Zezzio Arruda, Marco Aureli
    To determine whether the effect observed in a study is related to the nanoparticle only or to their synergic effect with the "free" metal ions, the real concentration of silver (104 +/- 8 and 100 +/- 2 mg L-1) after AgNP synthesis is obtained through ICP-MS and ICP OES in the solution after the AgNP synthesis and in different fractions after centrifugation (at 8100g for 40 min). From the resuspension of the AgNP contained in the solution (AgNP-total) after synthesis (AgNP-res), concentrations of 49 +/- 3 and 51 3 mg L-1 are found and concentrations of 50 +/- 7 and 47 +/- 2 mg L-1 in the supernatant (Ag-sup) are found using ICP-MS and ICP OES respectively. The characterization of AgNP-total, AgNP-res and Ag-sup is performed by HRTEM and UV-vis, corroborating the results in terms of Ag determination, and indicates that half of the total silver concentration is in the AgNP form and that the other half is in the "free" silver form. The results of the stability test of the NPs indicate a 7% decrease in Ag as NP three months after its synthesis. (C) 2015 Elsevier B.V. All rights reserved.
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    The importance of evaluating the real metal concentration in nanoparticles post-synthesis for their applications: A case-study using silver nanoparticles
    (Elsevier Science Bv, 2016) Galazzi, Rodrigo Moretto; Santos, Elias de Barros [UNIFESP]; Caurin, Tatiana; Pessoa, Gustavo de Souza; Mazali, Italo Odone; Zezzio Arruda, Marco Aureli
    To determine whether the effect observed in a study is related to the nanoparticle only or to their synergic effect with the "free" metal ions, the real concentration of silver (104 +/- 8 and 100 +/- 2 mg L-1) after AgNP synthesis is obtained through ICP-MS and ICP OES in the solution after the AgNP synthesis and in different fractions after centrifugation (at 8100g for 40 min). From the resuspension of the AgNP contained in the solution (AgNP-total) after synthesis (AgNP-res), concentrations of 49 +/- 3 and 51 3 mg L-1 are found and concentrations of 50 +/- 7 and 47 +/- 2 mg L-1 in the supernatant (Ag-sup) are found using ICP-MS and ICP OES respectively. The characterization of AgNP-total, AgNP-res and Ag-sup is performed by HRTEM and UV-vis, corroborating the results in terms of Ag determination, and indicates that half of the total silver concentration is in the AgNP form and that the other half is in the "free" silver form. The results of the stability test of the NPs indicate a 7% decrease in Ag as NP three months after its synthesis. (C) 2015 Elsevier B.V. All rights reserved.
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    Versatile interactions of boron fullerene b-80 with gas molecules
    (Univ Sao Paulo, Fac Saude Publica, 2016) Colherinhas, Guilherme; Fileti, Eudes Eterno [UNIFESP]; Chaban, Vitaly V. [UNIFESP]
    Stable all-boron fullerene B-80 supplements a family of elemental cage molecules. These molecules may initiate a drastic rise to intriguing new chemistry. The principal stability of B-80 was recently demonstrated using photoelectron spectroscopy. We report the systematic investigation of different aspects of B-80 interactions with small gas molecules-such as carbon dioxide, molecular hydrogen, hydrogen sulfide, hydrogen fluoride, ammonia and sulfur dioxide-employing density functional theory. We found peculiar interactions between B-80 and ammonia resulting in the formation of a weak boron-nitrogen covalent bond in one of their local-minimum configurations. Hydrogen fluoride maintains a weak hydrogen bond with B-80. The boron fullerene was found to be strongly polarizable, with its electron density distribution changing significantly even in the presence of low-polar gases. The binding energies of the gas molecules to B-80 are generally in direct proportion to their dipole moments. Valence bands are predominantly localized on B-80. According to the present findings, one of the prospective applications of B-80 in future may be gas capture and separation.