Nonlinear control in an electromechanical transducer with chaotic behaviour

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Effect of Ag nanoparticles on the radiative properties of tellurite glasses doped with Er3+, Yb3+ and Tm3+ ions

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Vertical distribution by demographic groups of ghost crab Ocypode quadrata (Crustacea: Brachyura)

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Transmissão indutiva de energia eletromagnética sem fios, para aplicações em postos de abastecimento de veículos elétricos puros: modelação para o elemento eletromagnético

Pós-graduação em Engenharia Elétrica - FEIS

EStudo fundamental da interação de nanopartículas metálicas com íons terras raras em vidros e vitrocerâmicas para aplicações na região do infravermelho

Pós-graduação em Química - IQ

Complexos heterobilantanídicos luminescentes sob excitação UV e raios X

Pós-graduação em Química - IQ

Life history and DNA barcode of Oxyurella longicaudis (Birgei, 1910) (Cladocera, Anomopoda, Chydoridae)

Background: Cladocera is an important group of freshwater zooplankton, and the species plays an important role in energy transfer and in aquatic food webs. Oxyurella longicaudis is a Chydoridae species that has been recorded in North and South America. The aim of this study is to investigate the life cycle aspects of parthenogenetic females of O. longicaudis cultured in laboratory under controlled conditions: temperature (23 degrees C +/- 05 degrees C), photoperiod (12 h light/12 h dark), food supply, and reconstituted water.Results: Embryonic development duration (2.3 +/- 0.5 days), post-embryonic development (5.2 +/- 0.69 days), mean fecundity (two eggs female(-1) brood(-1)), total egg production (22.55 +/- 3.98 eggs), average longevity (58 days), and body growth of the species were recorded. We also report the first DNA barcode for O. longicaudis isolated in Brazil, which will allow for easy identification in future zooplankton community studies. The analysis shows a genetic divergence of around 7% between our Brazilian isolate and O. longicaudis isolates from Mexico.Conclusions: The time of embryonic and post-embryonic development of O. longicaudis was higher than that of the other species of the same family, which contributed to lower total egg production throughout its life cycle. The genetic divergence appears to be sufficient to classify the two isolates as different species.

Does water level affect benthic macro-invertebrates of a marginal lake in a tropical river-reservoir transition zone?

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Caos e termalização na teoria de Yang-Mills-Higgs em uma rede espacial

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Metalosupramoléculas discretas e Metal Organic Frameworks (MOFs) baseados em íons lantanídeos: design, síntese, caracterização e propriedades

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Propriedades luminescentes de polioxometalato contendo európio(III) correlacionadas à sua conformação em sólido estendido e em filmes auto-organizados de Langmuir e Langmuir-Blodgett

Pós-graduação em Química - IQ

Color tunability of intense upconversion emission from Er3+-Yb3+ co-doped SiO2-Ta2O5 glass ceramic planar waveguides

This work reports on the infrared-to-visible CW frequency upconversion from planar waveguides based on Er3+-Yb3+-doped 100-xSiO(2)-xTa(2)O(5) obtained by a sol-gel process and deposited onto a SiO2-Si substrate by dip-coating. Surface morphology and optical parameters of the planar waveguides were analyzed by atomic force microscopy and the m-line technique. The influence of the composition on the electronic properties of the glass-ceramic films was followed by the band gap ranging from 4.35 to 4.51 eV upon modification of the Ta2O5 content. Intense green and red emissions were detected from the upconversion process for all the samples after excitation at 980 nm. The relative intensities of the emission bands around 550 nm and 665 nm, assigned to the H-2(11/2) -> I-4(15/2), S-4(3/2) -> I-4(15/2), and F-4(9/2) -> I-4(15/2) transitions, depended on the tantalum oxide content and the power of the laser source at 980 nm. The upconversion dynamics were investigated as a function of the Ta2O5 content and the number of photons involved in each emission process. Based on the upconversion emission spectra and 1931CIE chromaticity diagram, it is shown that color can be tailored by composition and pump power. The glass ceramic films are attractive materials for application in upconversion lasers and near infrared-to-visible upconverters in solar cells.

Persistent luminescence mechanisms: human imagination at work

The present status and future progress of the mechanisms of persistent luminescence are critically treated with the present knowledge. The advantages to be achieved by a further need as well as the pitfalls of the excessive use of imagination are shown. As usual, in the beginning of the present era of persistent luminescence since the mid 1990s, the imagination played a more important role than the sparse solid experimental data and the chemical common sense and knowledge was largely ignored. Since some five years, the mechanistic studies seem to have reached the maturity and - perhaps deceivingly - it seems that there are only details to be solved. However, the development of red emitting nanocrystalline materials poses a challenge also to the more fundamental studies and interpretation. The questions still luring in the darkness include the problems how the increased surface area affects the defect structure and how the "persistent energy transfer" really works. There is still some light to be thrown onto these matters starting with agreeing on the terminology: the term phosphorescence should be abandoned altogether. The long lifetime of persistent luminescence is due to trapping of excitation energy, not to the forbidden nature of the luminescent transition. However, the technically well-suited term "afterglow" should be retained for harmful, short persistent luminescence. (C) 2012 Optical Society of America

Novel europium and gadolinium complexes with methaneseleninate as ligand: Synthesis, characterization and spectroscopic study

The methaneseleninate and 1,10-phenanthroline were used as ligands in the synthesis of new lanthanide complexes. The photostability, emission quantum yield (q) and quantum efficiency (eta) of the D-5(0) emitting level of the Eu3+ ion were determined. An energy level diagram was used to establish the most relevant channels involved in the ligand-to-metal intramolecular energy transfer process. The nephelauxetic effect was investigated to assess the covalency of the ligand-metal chemical bond. The values of the experimental 4f-4f intensity parameters, suggest that this ion is in a chemical environment less polarisable than in the case of complexes with beta-diketonates as ligands. (C) 2011 Elsevier B.V. All rights reserved.

Photophysical properties of a fluorene-bipyridine copolymer and its complexes with europium

The synthesis and structural characterization of a europium complexed fluorene-bipyridine copolymer are described. A level of ion insertion of 80% in molar basis was achieved, and theoretical calculations showed that it required a twist of 179 degrees (49 kJ) between the pyridine units. Spectroscopy data showed that no electronic coupling between the main backbone and the complexation sites had occurred, but these hindered the interchain aggregation observed in the non complexed polymer. Preliminary electroluminescence studies showed that the EL and PL spectra are consistent, and that the ion had a trapping effect in the charge transport. (C) 2011 Elsevier B.V. All rights reserved.