Summary The declining reserves and environmental concerns related to the use of fossil fuels have made the global think tanks to pursue for the technologies considered to be renewable as well as sustainable. Fuel cell technology is emerging and a green way to produce electricity, provided sufficient amount of hydrogen (fuel) is available that directly convert chemical energy to electrical energy. Despite of being an efficient and eco‐friendly source of energy, commercialization of fuel cells is still difficult to attain. Techno‐economic challenges like high manufacturing and assembly costs, water management, system size, nondurability, and instability of the system need to be addressed. In order to resolve these issues, considerable research has been carried out for the development of novel and inexpensive materials for the fuel cells. In this article, we have reviewed the development of electrodes and electrolyte materials for different types of fuel cells. A detailed description of applications, challenges, and improvement of electrodes/electrolytes materials of different types of fuel cells (polymer electrolyte membrane fuel cells, direct methanol fuel cells and solid oxide fuel cells) have been reported in this review article. A brief review of the development of materials for electrode of molten carbonate fuel cells has also been presented in the review.

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The authors examined the activity of N-acetyltransferase and that of microsomal P-450 isoenzymes in health and hepatic disease state by determining the acetylation phenotype and the total (CLAP) and metabolic clearances of antipyrine to form norantipyrine or N-demethylantipyrine (MCLnora), 3-hydroxymethylantipyrine (MCLhma), and 4-hydroxyantipyrine (MCLha) in 21 healthy subjects and in 33 patients with chronic liver diseases (CLD) and investigated the relationship between the activities of these two enzyme systems. The acetylation phenotype was determined according to the urinary caffeine metabolites test. The mean and (SEM) of CLAP, MCLhma, MCLha, and MCLnora in healthy subjects were 2.42 (0.264), 0.193 (0.031), 0.322 (0.045), and 0.288 (0.04) L/h, and those observed in patients with CLD were 0.98 (0.1), 0.076 (0.015), 0.131 (0.026), 0.103 (0.022) L/h, respectively. The prevalence of fast acetylation among the healthy subjects and patients with CLD was 38% and 39%, respectively. Although all metabolic clearances appear to be reduced in healthy slow acetylators, the reduction was only significant in MCLnora, indicating a direct association between the activity of N-acetyltransferase and that of P-450 IIIA3 responsible for the N-demethylation of antipyrine. Conversely, slow acetylators with CLD exhibited significantly higher CLAP and near-significantly larger metabolic clearances including MCLnora, which suggests that P-450 activity in fast acetylators is more sensitive to chronic liver diseases than in slow acetylators.

We describe a simplified and rapid liquid chromatographic determination of antipyrine clearance (CLAP) calculated from peak height ratios of drug/internal standard. Saliva or plasma was collected 24 hr after the oral administration of 1 g of antipyrine to the subject. A 25-microliter aliquot of the sample is deproteinized with acetonitrile containing 3-nitrophenol (internal standard) and injected into a radial compression module equipped with a 10-micron, 8 mm x 10-cm C18 cartridge, using a 0.025 M aqueous solution of sodium acetate and acetonitrile (88.5:11.5). The minimum measurable concentration was 0.2 microgram/ml. The obtained CLAP values in five healthy subjects and five patients with chronic liver disease coincided well (r greater than 0.9994) with those generated by the use of an established method. The antipyrine clearance in the healthy subjects ranged from 2.203 to 5.721 liters/hr, while in patients with chronic liver disease it was significantly (P less than 0.0027) less (range, 0.544 to 1.103 liter/hr). We also determined antipyrine clearance in two of these subjects given lower doses of this drug and found that the dose has no significant impact on this parameter.

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