Analysis of a molten carbonate fuel cell: cogeneration to produce electricity and cold water

The fuel cell is an emerging cogeneration technology that has been applied successfully in Japan, the USA and some countries in the European Union. This system performs direct conversion of the chemical energy of the oxidation of hydrogen from fuel with atmospheric oxygen into direct current electricity and waste heat via an electrochemical process relying on the use of different electrolytes (phosphoric acid, molten carbonate and solid oxide, depending on operating temperature). This technology permits the recovery of waste heat, available from 200 degreesC up to 1000 degreesC depending on the electrolyte technology, which can be used in the production of steam, hot or cold water, or hot or cold air, depending on the associated recuperation equipment. In this paper, an energy, exergy and economic analysis of a fuel cell cogeneration system (FCCS) is presented. The FCCS is applied in a segment of the tertiary sector to show that it is a feasible alternative for rational decentralized energy production under Brazilian conditions. The technoeconomic analysis shows a global efficiency or fuel utilization efficiency of 86%. Analysis shows that the exergy losses in the fuel cell unit and the absorption refrigeration system are significant. Furthermore, the payback period estimated is about 3 and 5 years for investments in fuel cells of 1000 and 1500 US$/kW, respectively. (C) 2001 Elsevier B.V. Ltd. All rights reserved.

Fuel cell cogeneration system: a case of technoeconomic analysis

Fuel Cell is the emerging technology of cogeneration, and has been applied successfully in Japan, U.S.A. and some OECD countries. This system produces electric power by an electrolytic process, in which chemical substances (the most utilized substances are solid oxide, phosphoric acid and molten carbonate) absorb the components H-2 and O-2 of the combustion fuel. This technology allows the recovery of residual heat, available from 200 degrees C up to 1000 degrees C (depending on the electrochemical substance utilized), which can be used for the production of steam, hot or cold water, or hot or cold air, depending on the recuperation equipment used. This article presents some configurations of fuel cell cogeneration cycles and a study of the technical and economic feasibility for the installation of the cogeneration systems utilizing fuel cell, connected to an absorption refrigeration system for st building of the tertiary sector, subject to conditions in Brazil. (C) 1999 Elsevier B.V. Ltd. All rights reserved.

Determination of Population Size of Glass-like Carbon Sampling Used in Weibull Analysis

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

The Role of Lipopolysaccharide on the Electrochemical Behavior of Titanium

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Histomorphometric analysis of the repair process of autogenous bone grafts fixed at rat calvaria with cyanoacrylate

Objective: The purpose of this study was to perform histological and histometric analyses of the repair process of autogenous bone grafts fixed at rat calvaria with ethyl-cyanoacrylate adhesive. Material and Methods: Thirty-two rats were divided into two groups (n=16), Group I - Control and Group II - Adhesive. Osteotomies were made at the right parietal bone for graft obtainment using a 4-mm-diameter trephine drill. Then, the bone segments were fixed with the adhesive in the parietal region of the opposite side to the donor site. After 10 and 30 days, 8 animals of each group were euthanized and the calvarias were laboratorially processed for obtaining hematoxylin and eosin-stained slides for histological and histometric analyses. Results: An intense inflammatory reaction was observed at the 10-day period. At 30 days, this reaction was less intense, despite the presence of adhesive at the recipient-site/graft interface. Graft incorporation to the recipient site was observed only at the control group, which maintained the highest graft size at 10 and 30 days. Conclusions: Although the fragment was stable, the presence of adhesive in Group II did not allow graft incorporation to the recipient site, determining a localized, discrete and persistent inflammatory reaction.

Analysis of plant LTR-retrotransposons at the fine-scale family level reveals individual molecular patterns

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

A solid paraffin-based carbon paste electrode modified with 2-aminothiazole organofunctionalized silica for differential pulse adsorptive stripping analysis of nickel in ethanol fuel

A solid paraffin-based carbon paste electrode modified with 2-aminothiazole organofunctionalized silica (SiAt-SPCPE) was applied to Ni2+ determination in commercial ethanol fuel samples. The proposed method comprised four steps: (1) Ni2+ preconcentration at open circuit potential directly in the ethanol fuel sample, (2) transference of the electrode to an electrochemical cell containing DMG, (3) differential pulse voltammogram registering and (4) surface regeneration by polishing the electrode. The proposed method combines the high Ni2+ adsorption capacity presented by 2-aminothiazole organofunctionalized silica with the electrochemical properties of the Ni(DMG)2 complex, whose electrochemical reduction provides the analytical signal.All experimental parameters involved in the proposed method were optimized. Using a preconcentration time of 20 min, it was obtained a linear range from 7.5 x 10(-9) to 1.0 x 10(-6) mol L-1 with detection limit of 2.0 x 10(-9) mol L-1. Recovery values between 96.5 and 102.4% were obtained for commercial samples spiked with 1.0 mu mol L-1 Ni2+ and the developed electrode was totally stable in ethanolic solutions. The contents of Ni2+ found in the commercial samples using the proposed method were compared to those obtained by graphite furnace atomic absorption spectroscopy by using the F- and t-test. Neither the F- nor t-values exceeded the critical values at 95% confidence level, confirming that there are not statistical differences between the results obtained by both methods. These results indicate that the developed electrode can be successfully employed to reliable Ni2+ determination in commercial ethanol fuel samples without any sample pretreatment or dilution step. (c) 2006 Elsevier B.V. All rights reserved.

Highly Sensitive Neurotransmitters Analysis at Platinum-Ultramicroelectrodes Arrays

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

Geographic variation in cranial shape in the Pumpkin Toadlet (Brachycephalus ephippium): A geometric analysis

The description of patterns of variation in any character system within well-defined species is fundamental for understanding lineage diversification and the identification of geographic units that represent opportunities for sustained evolutionary divergence. In this paper, we analyze intraspecific variation in cranial shape in the Pumpkin Toadlet, Brachycephalus ephippium-a miniaturized species composed of isolated populations on the slopes of the mountain ranges of southeastern Brazil. Shape variables were derived using geometric-statistical methods that describe shape change as localized deformations in a spatial framework defined by anatomical landmarks in the cranium of B. ephippium. By statistically weighting differences between landmarks that are not close together (changes at larger geometric scale), cranial variation among geographic samples of B. ephippium appears continuous with no obvious gaps. This pattern of variation is caused by a confounding effect between within-sample allometry and among-sample shape differences. In contrast, by statistically weighting differences between landmarks that are at close spacing (changes at smaller geometric scale), differences in shape within- and among-sample variation are not confounded, and a marked geographic differentiation among population samples of B. ephippium emerges. The observed pattern of geographic differentiation in cranial shape apparently cannot be explained as isolation-by-distance. This study provides the first evidence that the detection of morphological variation or lack thereof, that is, morphological conservatism, may be conditional on the scale of measurement of variation in shape within the methodological formalism of geometric morphometrics.

An immunocytochemical and in situ hybridization analysis of annexin 1 expression in rat mast cells: Modulation by inflammation and dexamethasone

The presence and localization of the anti-inflammatory protein annexin 1 (also known as lipocortin 1) in perivenular rat mast cells was investigated here. Using the rat mesenteric microvascular bed and a combination of morphologic techniques ranging from immunofluorescence to electron microscopy analyses, we detected the presence of annexin 1 in discrete intracellular sites, both in the nucleus and in the cytoplasm. In resting mast cells, most of the protein pool (approximately 80% of the cytosolic portion) was localized to cytoplasmic granules. In agreement with other cell types, treatment of rats with dexamethasone (0.2 mg/kg, ip) increased annexin 1 expression in mast cells, inducing a remarkable appearance of dusters of protein immunoreactivity. This effect was most likely the result of de novo protein synthesis as determined by an increase in mRNA seen by in situ hybridization. Triggering an ongoing experimental inflammatory response (0.3 mg of carrageenin, ip) increased annexin 1 mRNA and protein levels. In conclusion, we report for the first time the localization of annexin 1 in connective tissue mast cells, and its susceptibility not only to glucocorticoid hormone treatment, but also to an experimental acute inflammatory response.

Localized matrix metalloproteinase (MMP)-2 and MMP-9 activity in the rat ventral prostate during the first week of postnatal development

The initial events in prostatic morphogenesis involve cell proliferation, epithelial canalization and outgrowth toward the stroma. We have hypothesized that stromal rearrangement takes place at the sites of epithelial growth and branching and that this rearrangement involves the action of gelatinases matrix metalloproteinase (MMP)-2 and MMP-9. Thus, the purpose of the present study was to characterize structural aspects of epithelial growth during the first week of postnatal development of the rat ventral prostate and to investigate the expression, localization and activity of MMP-2 and MMP-9 during this period by histological, ultrastructural and immunocytochemical analysis, in addition to gel zymography, in situ zymography and Western blotting. An increasing complexity of prostatic architeture was observed within the first postnatal week. Concurrently, the stroma became more organized and some cells differentiated into smooth muscle cells. Reticulin fibers appeared in a basket-like arrangement around both growing tips and epithelial sprouts, associated with a fainter staining for laminin. MMP-2 and MMP-9 activities were detected. MMP-2/MMP-9 expression decreased during the first week. Developing epithelial cords showed strong and difuse gelatinolytic activity. This activity coincided with the distribution of MMP-2 as determined by immunocytochemistry. on the other hand, MMP-9 was rather concentrated at the epithelial tips. These results suggest that gelatinolytic activity (with contribution of both MMP-2 and MMP-9) in the epithelium and at the epithelium-stroma interface are at least in part responsible for the tissue remodeling that allows epithelial growth and its projection into the surrounding stroma.

Electroluminescence and electric current response spectroscopy applied to the characterization of polymer light-emitting electrochemical cells

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

Thermal and electrochemical study of solid-state reaction of mercury with Pt-20% Rh alloy

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Symmetry breaking in a localized interacting binary Bose-Einstein condensate in a bichromatic optical lattice

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

Utilization of electrochemical impedance spectroscopy for monitoring bornite (CU5FeS4) oxidation by Acidithiobacillus ferrooxidans

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