Efeito da adição de nanopartículas de hexametafosfato de sódio em dentifrícios fluoretados sobre a desmineralização dentária: estudo in vitro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudos sobre a utilização de pentóxido de nióbio nanoestruturado na produção de biodiesel

In heterogeneous catalysis, numerous elements such as titanium and iron have been studied as nanoscale catalysts, but little is known about the use of niobium in nanocatalysis. The nanostructured particles have intrinsic and different physicochemical characteristics with great potential for use in industrial scale. Brazil having the largest known worldwide niobium reserve has the great challenge of creating pioneering technologies with the metal. Biodiesel is an alternative fuel and renewable substitute for regular diesel. Being biodegradable, non-toxic and have CO2 emissions lower than regular diesel, it contributes to the environment and to the independence from oil. The aim of this work was initially synthesize nanoscale particles of niobium pentoxide (Nanospheres, nanorods, nanofibers, nanocubes) from the sol-gel technique. The characterization of different nanoscale structures obtained was performed using different analytical techniques such as x-ray diffraction (XRD) and Scanning Electron Microscopy (SEM). The synthesized nanometer niobium oxide will be used as a heterogeneous catalyst in biodiesel synthesis from commercial soybean oil, checking in detail what the effect of morphology is presented (Nanospheres, nanorods, nanofibers, nanocubes) in the yield of biodiesel synthesis, comparing these results with those already described in literature for the amorphous niobium oxide and other oxide catalysts. The biodiesel obtained was characterized by gas chromatography system equipped with a FID detector

Dissolução redutiva de minério de ferro por Acidithiobacillus ferrooxidans para a recuperação de metais de interesse econômico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento de células solares de perovskita baseadas em filmes de óxidos nanoestruturados

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

Resposta dos tecidos periodontais aos cimentos de silicato tricálcico associado ao óxido de zircônio ou óxido de nióbio usados no selamento de perfurações de furca em molares de ratos

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

Estrutura e algumas propriedades ópticas de difenilfosfinatos de terras-raras

Coordination compounds of trivalent lanthanides cations with diphenylphosphinate are originated from direct reaction between a lanthanide salt and diphenylphosphinic acid. These complexes have peculiar and intriguing features, as (i) quickly obtainment through wet process precipitation, (ii) appreciable thermal stability, similar to inorganic phosphates, (iii) polymeric structure, and consequently, (iv) low solubility in both polar and non-polar solvents. Nowadays, coordination polymers are classified as coordination networks or, in case of porous materials, as metal-organic frameworks (MOFs). By this study, we aim to determine some optical properties of rare-earth diphenylphosphinate (RE = La3+, Eu3+, Gd3+, Lu3+) and conduct an updated classification of these compounds, bringing more details of its structure and the possible proposal of new materials with applications in lighting, detection of ionizing radiation and magnetism. The complexes of trivalent rare-earth cation with diphenylphosphinate were prepared by direct mixture of diphenylphosphinic acid with rare-earth metal chloride, both in ethanolic solution. The solution of diphenylphosphinic acid was kept in a beaker under constant stirring with pH measurements of the solution and gadolinium chloride solution was then dripped slowly with the aid of a burette until its complete addition; the following metal:ligand molar ratios were tested: 1:1, 1:2, 1:3, 2:1 e 3:1. The compounds were characterized by spectroscopic and structural techniques. By Fourier Transform Infrared Spectroscopy (FT-IR), it was possible to check the total ionization of diphenylphosphinic acid in synthesized complexes, confirmed by the absence of the band type A, B, C related to ѵ(O-H) of the acid (2663 cm-1, 2168 cm-1, 1684 cm-1), as well as the disappearance of ѵ(P-OH)=961 cm-1. Furthermore, the occurrence of bands shifts of ѵ(POO-) [symmetrical and asymmetrical] of...