Fernando Menegatti de Melo

Green Processing of Strategic Elements Based on Magnetic Nanohydrometallurgy

Magnetic nanohydrometallurgy (NHM) is a new process based on engineered superparamagnetic nanoparticles capable of performing as complexing agents for extracting and recovering strategic metals from mineral sources and urban wastes, as well as for removing hazardous elements from contaminated water. Its principles and application are reviewed in this paper. Typical examples involving copper, silver and mercury processing are here discussed, including the exploitation of a novel nanotechnological strategy for capturing and fractionating rare earth elements.

A new ferrous diflunisal complex and its effects on biopools of labile iron

Drugs bearing metal-coordinating moieties can alter biological metal distribution. In this work, a complex between iron(II) and diflunisal was prepared in the solid state, exhibiting the following composition: [Fe(diflunisal)2(H2O)2], (Fe(dif)2). The ability of diflunisal to alter labile pools of both plasmatic and cellular iron was investigated in this work. We found out that diflunisal does not increase the levels of redox-active iron in plasma of iron overloaded patients. However, diflunisal efficiently carries iron into HeLa or HepG2 cells, inducing an iron-catalyzed oxidative stress.

One-pot single step to label microtubule with MPA-capped CdTe quantum dots

The kinesin-microtubule pair has attracted much attention in recent years due to their promising use in the development of synthetic nanotransport machines. One of the challenges to study such system is how to observe the motility of either kinesin or microtubule. The usual technique for observation of the molecular machinery pair is by fluorescence microscopy, where fluorescent probes are bound to one, or both species, through a biotin-avidin linker. Here, the use of mercaptopropionic acid (MPA)-capped cadmium telluride (CdTe) quantum dots (QDs) as a direct fluorescent labeling agent to microtubule biomolecules is reported. QDs are able to not only bind to microtubules in vitro, but also to fluorescently label them in the red spectral region. Surface plasmon resonance (SPR) studies showed the binding of synthesized QDs to microtubules, while quantum dots-labeled microtubules were successfully visualized with fluorescence microscopy. It is believed QDs adsorbs to the microtubule surface mainly through the coordination of Cd with histidine, cysteine and methionine residues, as well as through interactions of the nanocrystals carboxylated surface with free amino groups on microtubules.

Extraction of Dysprosium Ions with DTPA Functionalized Superparamagnetic Nanoparticles Probed by Energy Dispersive X-ray Fluorescence and TEM/High-Angle Annular Dark Field Imaging

The extraction of dysprosium (Dy3+) ions from aqueous solution was carried out successfully, using magnetite (Fe3O4) nanoparticles functionalized with diethylenetriaminepentaacetic acid (MagNP@DTPA). The process was monitored by energy dispersive X-ray fluorescence spectroscopy, as a function of concentration, proceeding according to a Langmuir isotherm with an equilibrium constant of 2.57 × 10-3 g(MagNP) L-1 and a saturation limit of 63.2 mgDy/gMagNP. The presence of paramagnetic Dy3+ ions attached to the superparamagnetic nanoparticles led to an overall decrease of magnetization. By imaging the nanoparticles surface using scanning transmission electron microscopy equipped with high resolution elemental analysis, it was possible to probe the binding of the Dy3+ ions to DTPA, and to show their distribution in a region of negative magnetic field gradients. This finding is coherent with the observed decrease of magnetization, associated with the antiferromagnetic coupling between the lanthanide ions and the Fe3O4 core.

AS FRONTEIRAS PSICOLÓGICAS ENTRE VIOLÊNCIA, LUTA E BRINCADEIRA: AS TRANSIÇÕES FENOMENOLÓGICAS NA PRÁTICA DA CAPOEIRA.

The aim of this research is to understand experiences of Capoeira practitioners in the psychological transit between game, fight and quarrels, based on their own accounts. The methodological framework used was the phenomenological archeology of cultures. Three categories essentially describe how game, fight and quarrels really happen in Capoeira: the joy of playing; the game of complicity, and the denial of game. Moreover, the essential elements of transitions appear in two groups: game of prudences and tough game – emotionally guided by the dynamics between slowdown and combative intensification. Combative intensification is found to result either in violence or in the development of the fighting spirit, providing existential conditions for capoeira practitioners’ self-control.