Studies of the Electrochemical Degradation of Acetaminophen Using a Real-Time Biomimetic Sensor

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

Degradação eletroquímica do cloranfenicol em reator de fluxo

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

Espectroscopia de impedância eletroquímica aplicada ao estudo das reações heterogêneas em ânodos dimensionalmente estáveis

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

Mixed ionic-electronic YSZ/Ni composite for SOFC anodes with high electrical conductivity

The preparation of the ZrO(2):8 mol % Y(2)O(3)/NiO (YSZ/NiO) composites by a modified liquid mixture technique is reported. Nanometric NiO particles dispersed over the yttria-stabilized zirconia (YSZ) were prepared, resulting in dense sintered specimens with no solid solution formation between the oxides. Such a feature allowed for the electrical characterization of the composites in a wide range of relative volume fraction, temperature, and oxygen partial pressure. The main results indicate that the composites have high electrical conductivity, and the transport properties in these mixed ionic-electronic (MIEC) composites are strongly dependent on the relative volume fraction of the phases, microstructure, and temperature. These parameters should hence be taken into consideration for the optimized design of MIEC composites for electrochemical applications. In this context, the composite was reduced under H(2) for the preparation of high-conductivity YSZ/Ni cermets for use as solid oxide fuel cell anode material with relatively low metal content. (c) 2005 the Electrochemical Society. [DOI:10.1149/1.2149312] All rights reserved.

Influence of the indium concentration on microstructural and electrical properties of proton conducting NiO-BaCe0.9-xIn xY0.1O3-δ cermet anodes for IT-SOFC application

Optimization of the major properties of anodes based on proton conductors, such as microstructure, conductivity and chemical stability, is yet to be achieved. In this study we investigated the influence of indium on the chemical stability, microstructural and electrical characteristics of proton conducting NiO-BaCe0.9-xInxY0.1O 3-δ (NiO-BCIYx) anodes. Four compositions of cermet anode substrates NiO-BCIYx were prepared using the method of evaporation and decomposition of solutions and suspensions (EDSS). Sintered anode substrates were reduced and their microstructural and electrical properties were examined before and after reduction as a function of the amount of indium. Anode substrates tested on chemical stability in the CO2 atmosphere showed high stability compared to anode substrates based on commonly used doped barium cerates. Microstructural properties of the anode pellets before and after testing in CO2 were investigated using X-ray diffraction analysis. Impedance spectroscopy measurements were used for evaluation of electrical properties of the anode pellets and the conductivity values of reduced anodes of more than 14 S cm-1 at 600 °C confirmed percolations through Ni particles. Under fuel cell operating conditions, the cell with a Ni-BCIY20 anode achieved the highest performance, demonstrating a peak power density 223 mW/cm2 at 700 °C confirming the functionality of Ni-BCIY anodes.© 2013 Elsevier B.V. All rights reserved.

Stability, characterization and functionality of proton conducting NiO-BaCe0.85-xNbxY0.15O3-delta cermet anodes for IT-SOFC application

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

Microwave-assisted hydrothermal synthesis of NiO-Ce1-XEuxO2-δ powders for fuel cell catalytic anodes

CeO2-based materials doped with rare earth (TR +3) can be used as alternative to traditional NiO-YSZ anodes in solid oxide fuel cells as they have higher ionic conductivity and lower ohmic losses compared to YSZ. Moreover, they allow fuel cell operation at lower temperatures (500-800°C). In the anode composition, the concentration of NiO acting as catalyst in YSZ provides high electrical conductivity and high electrochemical activity of reactions, promoting internal reform in the cell. In this work, NiO - Ce1-xEuxO2-δ compounds (x = 0.1, 0.2 and 0.3) have been synthesized by microwave-assisted hydrothermal method. The materials were characterized by TG, XRD, TPR and SEM-FEG techniques. The refinement of data obtained by X-ray diffraction showed the presence of ceria doped with europium crystallized in a cubic phase with fluorite structure, in addition to the presence of NiO. The microwave-assisted hydrothermal method showed significant reduction in the average particle size and good mass control of phase compositions compared to other chemical synthesis techniques.

Enhanced photoelectrocatalytic degradation of an acid dye with boron-doped TiO2 nanotube anodes

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

Self-assembling of phenothiazine compounds investigated by small-angle X-ray scattering and electron paramagnetic resonance spectroscopy

Small-angle X-ray scattering (SAXS) and electron paramagnetic resonance (EPR) have been carried out to investigate the structure of the self-aggregates of two phenothiazine drugs, chlorpromazine (CPZ) and trifluoperazine (TFP), in aqueous solution. In the SAXS studies, drug solutions of 20 and 60 mM, at pH 4.0 and 7.0, were investigated and the best data fittings were achieved assuming several different particle form factors with a homogeneous electron density distribution in respect to the water environment. Because of the limitation of scattering intensity in the q range above 0.15 angstrom(-1), precise determination of the aggregate shape was not possible and all of the tested models for ellipsoids, cylinders, or parallelepipeds fitted the experimental data equally well. The SAXS data allows inferring, however, that CPZ molecules might self-assemble in a basis set of an orthorhombic cell, remaining as nanocrystallites in solution. Such nanocrystals are composed of a small number of unit cells (up to 10, in c-direction), with CPZ aggregation numbers of 60-80. EPR spectra of 5- and 16-doxyl stearic acids bound to the aggregates were analyzed through simulation, and the dynamic and magnetic parameters were obtained. The phenothiazine concentration in EPR experiments was in the range of 5-60 mM. Critical aggregation concentration of TFP is lower than that for CPZ, consistent with a higher hydrophobicity of TFP. At acidic pH 4.0 a significant residual motion of the nitroxide relative to the aggregate is observed, and the EPR spectra and corresponding parameters are similar to those reported for aqueous surfactant micelles. However, at pH 6.5 a significant motional restriction is observed, and the nitroxide rotational correlation times correlate very well with those estimated for the whole aggregated particle from SAXS data. This implies that the aggregate is densely packed at this pH and that the nitroxide is tightly bound to it producing a strongly immobilized EPR spectrum. Besides that, at pH 6.5 the differences in motional restriction observed between 5- and 16-DSA are small, which is different from that observed for aqueous surfactant micelles.

Value of ultrasonographic contrast in duplex scanning of leg arteries - Comparison with conventional duplex scanning and arteriography

Aim. Duplex scanning has been used in the evaluation of the aorta and proximal arteries of the lower extremities, but has limitations in evaluating the arteries of the leg. The utilization of ultrasonographic contrast (USC) may be helpful in improving the quality of the image in these arteries. The objective of the present study was to verify whether the USC increases the diagnostic accuracy of patency of the leg arteries and if it diminishes the time needed to perform duplex scanning.Methods. Twenty patients with critical ischemia (20 lower extremities) were examined by standard duplex scanning, duplex scanning with contrast and digital subtraction arteriography (DSA). The 3 arteries of the leg were divided into 3 segments, for a total of 9 segments per limb. Each segment was evaluated for patency in order to compare the 3 diagnostic methods. Comparison was made between standard duplex scanning and duplex scanning with contrast in terms of quality of the color-coded Doppler signal and of the spectral curve, and also of the time to perform the exams.Results. Duplex scanning with contrast was similar to arteriography in relation to patency diagnosis (p>0.3) and even superior in some of the segments. Standard duplex scanning was inferior to arteriography and to duplex scanning with contrast (p<0.001). There were improvements of 70% in intensity of the color-coded Doppler signal and 76% in the spectral curve after the utilization of contrast. The time necessary to perform the examinations was 23.7 minutes for standard duplex scanning and 16.9 minutes for duplex scanning with contrast (p<0.001).Conclusion. The use of ultrasonographic contrast increased the accuracy of the diagnosis of patency of leg arteries and diminished the time necessary for the execution of duplex scanning.

GABA(A) receptor activation in the lateral parabrachial nucleus induces water and hypertonic NaCl intake

Inhibitory serotonergic and cholecystokinergic mechanisms in the lateral parabrachial nucleus and central GABAergic mechanisms are involved in the regulation of water and NaCl intake. In the present study we investigated if the GABA(A) receptors in the lateral parabrachial nucleus are involved in the control of water, NaCl and food intake in rats. Male Holtzman rats with stainless steel cannulas implanted bilaterally into the lateral parabrachial nucleus were used. Bilateral injections of muscimol (0.2 nmol/0.2 mu l) into the lateral parabrachial nucleus strongly increased 0.3 M NaCl (20.3 +/- 7.2 vs. saline: 2.6 +/- 0.9 ml/180 min) without changing water intake induced by the treatment with the diuretic furosemide combined with low dose of the angiotensin converting enzyme inhibitor captopril s.c. In euhydrated and satiated rats, bilateral lateral parabrachial nucleus injections of muscimol (0.2 and 0.5 nmol/0.2 0) induced 0.3 M NaCl intake (12.1 +/- 6.5 and 32.5 +/- 7.3 ml/180 min, respectively, vs. saline: 0.4 +/- 0.2 ml/180 min) and water intake (5.2 +/- 2.0 and 7.6 +/- 2.8 ml/ 180 min, respectively, vs. saline: 0.8 +/- 0.4 ml/180 min), but no food intake (2 +/- 0.4 g/240 min vs. saline: 1 +/- 0.3 g/240 min). Bilateral lateral parabrachial nucleus injections of the GABAA antagonist bicuculline (1.6 nmol/0.2 mu l) abolished the effects of muscimol (0.5 nmol/0.2 mu l) on 0.3 M NaCl and water intake. Muscimol (0.5 nmol/0.2 mu l) into the lateral parabrachial nucleus also induced a slight ingestion of water (4.2 +/- 1.6 ml/240 min vs. saline: 1.1 +/- 0.3 ml/240 min) when only water was available, a long lasting (for at least 2 h) increase on mean arterial pressure (14 +/- 4 mm Hg, vs. saline: -1 +/- 1 mm Hg) and only a tendency to increase urinary volume and Na+ and K+ renal excretion. Therefore the activation of GABAA receptors in the lateral parabrachial nucleus induces strong NaCl intake, a small ingestion of water and pressor responses, without changes on food intake. (c) 2005 Published by Elsevier Ltd on behalf of IBRO.

Cardiovascular responses to hydrogen peroxide into the nucleus tractus solitarius

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

Materiais cerâmicos de inserção aplicados a baterias de íons lítio

Esta revisão visa ser uma introdução à aplicação de materiais cerâmicos em dispositivos de armazenamento de energia, em especial baterias secundárias de íons lítio, dispositivos nos quais os materiais cerâmicos, especialmente óxidos, são muito importantes em todas as partes do dispositivo. A revisão está focada nos materiais cerâmicos para catodos e anodos, partes chaves destes dispositivos. Ela tem por principal finalidade ser uma fonte de informação para aqueles que desejem trabalhar com o desenvolvimento de materiais cerâmicos para tais tipos de dispositivos. Aspectos relacionados à nanotecnologia e materiais óxidos nanoestruturados para esta área são discutidos ao final do artigo.