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  • methane  (2)
  • Cell & Developmental Biology  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Adsorption 6 (2000), S. 179-188 
    ISSN: 1572-8757
    Keywords: pressure swing adsorption ; methane ; hydrogen ; process design
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The performance of a pressure swing adsorption (PSA) process for production of high purity hydrogen from a binary methane-hydrogen mixture is simulated using a detailed, adiabatic PSA model. An activated carbon is used for selective adsorption of methane over hydrogen. The effects of various independent process variables (feed gas pressure and composition, purge gas pressure and quantity, configuration of process steps) on the key dependent process variables (hydrogen recovery at high purity, hydrogen production capacity) are evaluated. It is demonstrated that many different combinations of PSA process steps, their operating conditions, and the feed gas conditions can be chosen to produce an identical product gas with different hydrogen recovery and productivity.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8757
    Keywords: kinetics ; isotope-exchange ; nitrogen ; adsorption ; methane ; zeolite ; equilibria
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Physics , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The Isotope Exchange Technique (IET) was used to simultaneously measure pure and binary gas adsorption equilibria and kinetics (self-diffusivities) of CH4 and N2 on pelletized 4A zeolite. The experiment was carried out isothermally without disturbing the adsorbed phase. CH4 was selectively adsorbed over N2 by the zeolite because of its higher polarizability. The multi-site Langmuir model described the pure gas and binary adsorption equilibria fairly well at three different temperatures. The selectivity of adsorption of CH4 over N2 increased with increasing pressure at constant gas phase composition and temperature. This curious behavior was caused by the differences in the sizes of the adsorbates. The diffusion of CH4 and N2 into the zeolite was an activated process and the Fickian diffusion model described the uptake of both pure gases and their mixtures. The self-diffusivity of N2 was an order of magnitude larger than that for CH4. The pure gas self-diffusivities for both components were constants over a large range of surface coverages (0 〈 θ 〈 0.5). The self-diffusivities of CH4 and N2 from their binary mixtures were not affected by the presence of each other, compared to their pure gas self-diffusivities at identical surface coverages.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Cellular Physiology 134 (1988), S. 467-472 
    ISSN: 0021-9541
    Keywords: Life and Medical Sciences ; Cell & Developmental Biology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Medicine
    Notes: Variants (G2, G5) resistant to the cancer chemotherapeutic drug methylglyoxal bis (guanylhydrazone) (MGBG) were isolated from adenovirus type 2 transformed rat brain cells (F4; Sircar et al., 1987). Although at least one of these variants continued to express the adenovirus Ela and Elb transforming proteins, they both exhibited a detransformed phenotype as witnessed by flat morphology, loss of anchorage independent growth, and tumor forming capacity. Reverse transformation suggested the possibility of changes in growth factor receptors and the production of transforming growth factors. To test this possibility, we investigated the status of epidermal growth factor receptors (EGF-r) and transforming growth factor alpha (TGF-α) production in F4, G2 and G5 cells. The level of 125I-labeled EGF binding to intact drug resistant cells increased by 2- to 3-fold compared to the transformed parental cell. Scatchard analysis suggests that increased binding was the result of increased receptor levels rather than altered affinity of receptor for ligand. The production of growth factors which compete with 125I-labeled EGF binding declined in the detransformed G2 and G5 cells to a level intermediate between transformed (F4) and normal cells (FR3T3). EGF-receptor increase and the complementary decrease in growth factor production in the drug resistant variants may be associated with detransformation.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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