Facile synthesis and characterization of ZrO2 nanoparticles prepared by the AOP/hydrothermal route

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

Correlation between structural and electronic order-disorder effects and optical properties in ZnO nanocrystals

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

Silver Molybdate and Silver Tungstate Nanocomposites with Enhanced Photoluminescence

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Experimental and theoretical studies of photoluminescence in Zns obtained by microwave-assisted solvothermal method

A shift of the photoluminescence (PL) emission was observed in ZnS prepared by microwave assisted solvothermal method with the increase of the time in microwave. In this work we reported a study of the optical behavior linking with the structural disorder according to XRD and FEG-TEM results. The reduction of intrinsic defects in the lattice is responsible for the decrease of electronic levels in the band gap changing the PL profile. This effect was confirmed by electronic structure calculations.

SnO2 dense ceramic microwave sintered with low resistivity

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Influence of the preparation route on the structural, morphological and spectroscopic properties of SrTiO3 and SrTiO3:eu3+ powders

This research shows the influence of the synthesis route in the structural and morphological characteristics as well as in the luminescent properties of doped with europium and pure SrTiO3 (STO) powders prepared by microwave assisted hydrothermal synthesis, MWH, and by the polymeric precursor method, PPM. The XRD at room temperature of the STO powders nominally pure obtained by PPM at 700°C for 3 hours, as well as by the MWH at 190°C by 30 minutes present all the reflection peaks for the cubic perovskite structure (JCPDS-ICDD 35-734). The morphology varies according to the synthesis route. The particles of pure STO obtained by PPM presents morphology in the form of plates and the morphology of the particles synthesized by MWH is spherical with approximately 150 nm. The photoluminescent analysis shows for pure STO wide bands associated with the transition of charge transfer from the titanates group (TiO3)2- that are centered on 450 nm. In both preparation methods the emission bands obtained in the composites spectra were found to be asymmetric and low intense. However, in the case of the STO prepared by the PPM a bigger FWHM of the band can be observed. The excitation of the samples was done using a laser (Coherent Innova) with wavelength of 350 nm.

Ethyl biodiesel: Microwave irradiation aiding ethanolysis of waste cooking oil.

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

Microwave interferometric technique for characterizing few mode fibers

We propose and experimentally demonstrate a simple and accurate technique for measuring differential mode group delay (DMGD) in few mode fibers (FMF). A frequency-swept microwave signal is modulated on a filtered optical incoherent source. The microwave signals carried on different fiber modes experience different time delays and interfere with each other in the photodetector. Optical interference between propagating fiber modes is avoided by the use of an incoherent optical source. A mathematical model is established to analyze the interference pattern and extract the DMGD values. A 456-m two-mode fiber and a 981-m FMF, which supports four LP modes, are measured. The measurement covers the whole C-band and the results coincide well with those obtained by the time-of-flight method and the numerical simulations. A precision of ±0.002 ps/m is achieved.

Obtenção e caracterização de nanoestruturas puras e dopadas a base de 'TI''O'IND.2' para a aplicação em fotocatálise

Pós-graduação em Química - IQ

Otimização do processamento de partículas lead-free para aplicação em compósitos polímero/cerâmica com propriedades piezoelétrica e fotoluminescente

Pós-graduação em Química - IQ

Cell membrane integrity of candida albicans after different protocols of microwave irradiation

To evaluate the ability of low time microwaveexposureto inactivate and damage cell membrane integrity of C. albicans. Materials and Methods: Two 200ml C. albicans suspensions were obtained. Sterile dentures were placed in a beaker containing Experimental (ES) or Control suspensions (CS). ES was microwaved at 650 W for 1, 2, 3, 4 or 5 min. Suspensions were optically counted using Methylene blue dye as indicative of membrane-damaged cells; spread on Agar Sabouraud dextrose (ASD) for viability assay; or spectrophotometrically measured at 550nm. Cell-free solutions were submitted to content analyses of protein (Bradford and Pyrogallol red methods); Ca++ (Cresolphthalein Complexone method); DNA (spectrophotometer measurements at 260nm) and K+ (selective electrode technique). Data were analyzed by Student-t test and linear regression (α=0.05). In addition, flowcytometry analysis of Candida cells in suspensionwas performed using propidium iodide. Results: All ES cells demonstrated cell membrane damage at 3, 4 and 5 min,viable cells were nonexistent at 3, 4 and 5 min ES ASD plates and optical density of ES and CS was not significantly differentfor all exposition times. ES cells released highcontents of protein, K+ , Ca++ and DNA after 2 min exposition when compared to that of the CSs. Similar results were observed with flow cytometry analysiswith regard to the periodsof microwave exposure. Conclusions: Microwave irradiation inactivated C. albicansafter 3min and damaged cell membrane integrity after 2 min exposition.

Evaluation of microwave-assisted pretreatment of lignocellulosic biomass immersed in alkaline glycerol for fermentable sugars production

A pretreatment with microwave irradiation was applied to enhance enzyme hydrolysis of corn straw and rice husk immersed in water, aqueous glycerol or alkaline glycerol. Native and pretreated solids underwent enzyme hydrolysis using the extract obtained from the fermentation of Myceliophthora heterothallica, comparing its efficiency with that of the commercial cellulose cocktail Celluclast (R). The highest saccharification yields, for both corn straw and rice husk, were attained when biomass was pretreated in alkaline glycerol, method that has not been previously reported in literature. Moreover, FTIR, TG and SEM analysis revealed a more significant modification in the structure of corn straw subjected to this pretreatment.Highest global yields were attained with the crude enzyme extract, which might be the result of its content in a great variety of hydrolytic enzymes, as revealed zymogram analysis. Moreover, its hydrolysis efficiency can be improved by its supplementation with commercial beta-glucosidase.

The role of oxygen vacancies and their location in the magnetic properties of Ce1-xCuxO2-delta nanorods

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Photoluminescence of BaZrO3 explained by a order/disorded transformation

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Fingerprints of short-range and long-range structure in BaZr1-xHfxO3 solid solutions: an experimental and theoretical study

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