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Carvalho J.M.,University of Sao Paulo | Carvalho J.M.,University of Turku | Lastusaari M.,University of Turku | Rodrigues L.C.V.,University of Sao Paulo | And 3 more authors.
Journal of Luminescence | Year: 2015

Praseodymium doped ZrO2 materials were prepared via sol-gel route and structurally characterized by X ray powder diffraction (XPD) technique as well as Rietveld refinements. The addition of the Gd3+ co-dopant gradually changes the zirconia structure from monoclinic to tetragonal, and then to cubic. Intensification of the Pr3+ luminescence was observed with the increasing Gd3+ co-dopant concentration. Emission spectra of the Zr0.99-x Gd x Pr0.01O2 materials show an initial strengthening of the red emission of Pr3+ (1D2→3H4 transition) with increasing Gd3+ co-doping. However, the luminescence is quenched at the highest Gd3+ concentration-possibly due to strongly increased concentration of the charge compensation defects. The valence change (PrIV→Pr3+) is supported by the XANES results on the LIII edge of Pr. Although predominantly in the Pr3+ form irrespective of the Gd3+ concentration, the contribution from PrIV is clearly visible at low (or zero) Gd3+ concentrations leading to the loss of Pr3+ and to poor luminescence output. Though enhancing the emission intensity of Pr3+, the defect clusters engender short Pr3+-Pr3+ distances enhancing the cross-relaxation process coupling the 3P0→1D2 relaxation with the 3H4→3H6 excitation. This process leads to the high red/blue-green emission ratio by quenching the 3P0→3H4 transition in blue-green. Eventually, the increased Gd3+ co-doping dilutes the Pr3+ ions and, the cross-relaxation process becomes non-operational; the quenching of the 3P0→3H4 transition is reversed. © 2015 Elsevier B.V.


Carvalho J.M.,University of Sao Paulo | Carvalho J.M.,University of Turku | Lastusaari M.,University of Turku | Rodrigues L.C.V.,University of Sao Paulo | And 4 more authors.
Journal of Luminescence | Year: 2016

Praseodymium doped ZrO2 materials were prepared via sol-gel route and structurally characterized by X ray powder diffraction (XPD) technique as well as Rietveld refinements. The addition of the Gd3+ co-dopant gradually changes the zirconia structure from monoclinic to tetragonal, and then to cubic. Intensification of the Pr3+ luminescence was observed with the increasing Gd3+ co-dopant concentration. Emission spectra of the Zr0.99-xGdxPr0.01O2 materials show an initial strengthening of the red emission of Pr3+ (1D2→3H4 transition) with increasing Gd3+ co-doping. However, the luminescence is quenched at the highest Gd3+ concentration-possibly due to strongly increased concentration of the charge compensation defects. The valence change (PrIV→Pr3+) is supported by the XANES results on the LIII edge of Pr. Although predominantly in the Pr3+ form irrespective of the Gd3+ concentration, the contribution from PrIV is clearly visible at low (or zero) Gd3+ concentrations leading to the loss of Pr3+ and to poor luminescence output. Though enhancing the emission intensity of Pr3+, the defect clusters engender short Pr3+-Pr3+ distances enhancing the cross-relaxation process coupling the 3P0→1D2 relaxation with the 3H4→3H6 excitation. This process leads to the high red/blue-green emission ratio by quenching the 3P0→3H4 transition in blue-green. Eventually, the increased Gd3+ co-doping dilutes the Pr3+ ions and, the cross-relaxation process becomes non-operational; the quenching of the 3P0→3H4 transition is reversed. © 2015 Elsevier B.V. All rights reserved.


das Nevesa M.D.M.,Brazilian Nuclear Energy Research Institute (IPEN) | Lottob A.,Sao Paulo State University | de Rossid W.,Institute of Energy and Nuclear Research | Juniord N.D.V.,Institute of Energy and Nuclear Research
Welding International | Year: 2010

In this work, the morphology of solidification of the weld zone (WZ) was studied in a joint formed from dissimilar materials, composed of austenitic AISI 304 stainless steel and Inconel 600 nickel alloy, welded with an Nd:YAG-pulsed laser. The laser beam and optical system parameters were selected with a view to obtain a weld with total penetration and good surface finish. The microstructural characterization was carried out using an optical microscope, in which a WZ was seen with total penetration, keyhole-type, presence of small pores and absence of cracks. The welded joints were also characterized by means of an electron scan microscope. Measurements taken by X-ray spectrometry for dispersion of the energy in the WZ indicated a slightly heterogeneous distribution of nickel and iron. It was seen that the start of solidification in the WZ occurred by means of epitaxial growth. The morphology of WZ solidification was basically denditric and cellular, being influenced by the temperature gradient, solidification speed and chemical composition. The variations in chemical composition and solidification morphology do not significantly alter the Vickers microhardness values in the WZ. Results obtained in the tensile tests indicate suitably effective welding values. © 2010 Taylor & Francis.


Faintuch B.L.,Institute of Energy and Nuclear Research | Oliveira E.A.,Institute of Energy and Nuclear Research | Targino R.C.,Butantan Institute | Moro A.M.,Butantan Institute
Applied Radiation and Isotopes | Year: 2014

The asparagine-glycine-arginine (NGR) peptide sequence found by phage display, was radiolabeled with technetium-99. m and tested in different tumor models. Similar uptake occurred with ovarian and lung tumor cells. Biodistribution of the radiotracer revealed predominant renal excretion with more substantial uptake in animals bearing ovarian tumor cells. In contrast imaging studies indicated better visualization for lung tumor. NGR peptide was characterized as a promising diagnostic candidate, particularly for lung cancer. Improvements are envisaged using NGR combined with RGD as a heterodimer molecule. © 2014 Elsevier Ltd.


Faintuch B.L.,Institute of Energy and Nuclear Research | Oliveira E.A.,Institute of Energy and Nuclear Research | Munoz J.E.,University of Sao Paulo | Travassos L.R.,Federal University of Sao Paulo | Taborda C.P.,University of Sao Paulo
Medical Mycology | Year: 2014

Paracoccidioidomycosis (PCM) is a chronic granulomatous disease that is caused by the thermally dimorphic fungus Paracoccidioides brasiliensis. It is endemic in some countries of Latin America and can cause a high-burden fungal infection with significant morbidity and mortality. The peptide P10, which demonstrates immune protection against experimental PCM, was radiolabeled with a radioisotope and evaluated in vivo. The radiolabeling was conducted to trace the pharmacokinetics of the molecule in principal organs and tissues. This was achieved with high radiochemical purity. Biodistribution and scintigraphic imaging showed fast blood clearance that was mainly renal; however, hepatobiliar excretion was also, with marked uptake in cervical lymph nodes. This profile may be useful for the development of a prophylactic drug or vaccine for patients exposed to PCM. © 2014 The Author.

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