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  • 1995-1999  (7)
  • 1998  (4)
  • 1997  (3)
  • 1
    Electronic Resource
    Electronic Resource
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 68 (1997), S. 3540-3543 
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: This work describes the characteristics of a bench station designed for both the control of the operational parameters of a unitary, low temperature fuel cell and the data acquisition for performance evaluation. The controlled parameters are the current through the cell, the pressure and the flow of the reactants, and the temperature of the cell and of the gaseous reactants. The system measures the potential drop across the cell and the potential of each electrode with respect to a reference, as a function of the current, which is varied on a predetermined interval. The program plots the results and fits the experimental curve to a theoretical expression, which allows the determination of the cell resistance and the Tafel kinetic parameters of the cell reactions. The test station provides a rapid route to the work with single/half cells in the evaluation of materials and fuel cell performance. The computer controlled procedures, data acquisition, and analyses proposed here substitute with advantages time consuming manual procedures. © 1997 American Institute of Physics.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Oxford, UK : Blackwell Publishing Ltd
    Journal of fish biology 53 (1998), S. 0 
    ISSN: 1095-8649
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Biology
    Notes: The reef fish community of the Mexican Caribbean and the factors governing its structure are poorly known. Using canonical correspondence analysis (CCA), the relationship between fish community species composition and abundance, and environmental variables was investigated at three Mexican Caribbean reefs. These reefs are separated by c. 70 km: Boca Paila, located in the northern Sian Ka'an Biosphere Reserve; Tampalam, in the southern portion of said reserve; and Majahual, an unprotected area near the Mexico/Belize border. One hundred and thirty-four fish species belonging to 41 families were identified by underwater visual census. Their quantitative data, and 15 environmental variables collected during 60 sample transects, were analysed. The sample stations were distributed among the three reefs, and covered five dominant habitat types: reef lagoon, back reef, reef crest, reef front and reef slope. The variables estimated were: temperature, depth, current direction, current intensity, vertical relief, visibility, topographical complexity and substratum coverage (percent of sand, seagrass, algae, rock and rubbles, gorgonians, massive coral, branching coral and encrusting coral). Ordination diagrams with points based on fish species, sample sites, and environmental variables, showed a pattern mainly determined by degree of reef site complexity. Habitat scale environmental factors defined element distribution in three main areas: (a) reef fish species associated with lagoon and back reef sites of low topographical complexity; (b) species associated with intermediate complexity reef crest sites; and (c) species associated with high complexity reef front and reef slope sites. Nearly 52% of the variation in fish species data was explained by environmental variables in the direct and simultaneous ordination analysis. Topographical complexity was the most important variable, but depth, encrusting coral coverage, and vertical relief also had significant effect on fish species. Use of multivariate statistical methods proved valuable in deciphering the reef fish community structure patterns in the southern Mexican Caribbean. The current study provides a base for future reef fish research and regional tourism and fisheries management.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Oxford [u.a.] : International Union of Crystallography (IUCr)
    Acta crystallographica 53 (1997), S. 311-313 
    ISSN: 1600-5759
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Chemistry and Pharmacology , Geosciences , Physics
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of applied electrochemistry 27 (1997), S. 19-24 
    ISSN: 1572-8838
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Electrical Engineering, Measurement and Control Technology
    Notes: Abstract In this work results on the preparation, characterization and single cell testing of matrices for phosphoric acid fuel cells are reported. The matrices were produced using mixtures of powders of silicon carbide with zirconium silicate or niobium carbide, by deposition of an aqueous emulsion of the powders on top of the catalyst layer of the gas diffusion electrodes, or by making a self-supported film of the materials. The physical characterization of the powders and of the matrices included the distribution of particle size and shape of the powders and the thickness, electrical resistance, and pore size distribution in the matrices. The matrices were evaluated under operation, using standard supported platinum on carbon gas diffusion electrodes in a H2O2 single fuel cell setup operating with phosphoric acid at 180. The results of the cell potential; current density characteristics were analysed to separate the contribution of the structural properties of the matrices on the total polarization losses of the single cells. It was found that a single cell operating with a self-supported matrix composed of 50wt% NbC+SiC has a much better performance than that observed with SiC alone.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1432-2277
    Keywords: Key words Liver transplantation ; Tacrolimus ; Rejection ; Toxicity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Eighty-four adult patients were recruited from four centres in Spain to evaluate the efficacy and safety of low-dose (0.1 mg/kg per day) oral tacrolimus plus corticosteroid immunosuppression in liver transplantation. The median daily dose of tacrolimus was increased during the first 3 weeks of therapy from an initial dose of 0.1 mg/kg per day to a maximum of 0.145 mg/kg per day and was subsequently decreased gradually to a minimum of 0.076 mg/kg per day at 1 year. At 7 days posttransplantation, 87.7 % of patients had trough whole blood levels of tacrolimus within the therapeutic range (5–20 ng/ml), and the median levels remained fairly constant during the rest of the year (10.1–11.8 ng/ml). None of the patients required intravenous administration of tacrolimus. At 1 year, Kaplan-Meier estimates showed that 73.8 % of the patients were receiving tacrolimus monotherapy without the need for corticosteroids. One-year patient and graft survival were 75.9 % and 72.3 %, respectively. The incidence of acute rejection was 51.2 %; 9.5 % of cases resolved spontaneously without antirejection therapy and 10.7 % were corticosteroid resistant. Only 1 patient (1.2 %) developed chronic rejection. The most important adverse events were hypertension (45.2 %), tremor (44.0 %), diabetes mellitus (33.3 %), diarrhoea (31 %) and nephrotoxicity (29.8 %). Severe neurotoxicity-like convulsions (4.8 %), dysarthria (9.5 %), delirium (1.2 %), coma (1.2 %) and the need for haemodialysis (3 patients) were uncommon. In conclusion, low-dose oral tacrolimus immunosuppression is associated with low toxicity without compromising efficacy.
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-8698
    Keywords: Polynomial differential equations ; limit cycles ; monodromy group ; conformal maps ; fixed points
    Source: Springer Online Journal Archives 1860-2000
    Topics: Electrical Engineering, Measurement and Control Technology
    Notes: Abstract Differential equations on the complex plane with a rational right-hand side are considered. In a generic case such equation has a countable set of homologically independent limit cycles. It is proved that the exceptional set – the set of equations such that they do not have this property – has the real codimension at least two in the space of equations with right-hand side of degree no greater than a fixed number n.
    Type of Medium: Electronic Resource
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  • 7
    ISSN: 1573-2568
    Keywords: HEPATOCELLULAR CARCINOMA ; SURGERY ; RECURRENCE
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Type of Medium: Electronic Resource
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