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  • 1
    Electronic Resource
    Electronic Resource
    An exact renormalization-group approach for local phonon properties of single-atom and double-atom generalized Fibonacci systems (1993)
    Springer
    The European physical journal 91 (1993), S. 467-474 
    Details
    ISSN: 1434-6036
    Keywords: 63.50.+x ; 71.20.Ad ; 61.42+h
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract We present an exact renormalization-group approach to study the local phonon properties of the double-atom generalized Fibonacci systems in which the masses and spring constants are all associated with the aperiodic sequences constructed by the inflation rule: {A, B}→{A n Bm, A}.n(m+1) basic transformations and 2n(n+m−1)+1 basic decimations are introduced. By applying the combinations of derived transformations and decimations, we can determine exactly the renormalized local environment, up to infinite order, of any given site in the double-atom systems. Both the single-atom and double-atom phonon models are employed, and the local density of states in several sites of some generalized Fibonacci systems are numerically calculated.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01316825
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  • 2
    Electronic Resource
    Electronic Resource
    Study of the chromatographic behavior and inclusion constants of new fluorescence agents by use of cyclodextrin additives under conditions of steady- and dynamic-state equilibrium and with fluorescence detection (1999)
    Springer
    Chromatographia 49 (1999), S. 95-104 
    Details
    ISSN: 1612-1112
    Keywords: Column liquid chromatography ; Cyclodextrin additives ; Fluorescence agents
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary We report four new derivatization agents, acridone-N-acetic acid (ARC), carbazole-9-ylacetic acid (CRA), carbazole-9-ylpropionic acid (CRP), and 2-methyl-2-carbazole-9-ylacetic acid (MCRA), with strong fluorescence emission which has low dependence on solvent polarity. The emission maxima for ARC, CRA, CRP, and MCRA were 430 nm (λex 404 nm), 368 nm (λex 335 nm), 356 nm (λex 340 nm) and 360 nm (λex 330 nm), respectively. The effects of mobile-phase composition, pH, and temperature on the liquid chromatographic retention behavior of the four fluorescence agents were investigated. An experimental model was established for calculating the inclusion constants of cyclodextrin (CD) complexes in the dynamic state, using β-cyclodextrin (β-CD) and hydroxypropyl-β-cyclodextrin (HP-β-CD) as examples, and different mobilephase compositions. On the basis of the model, the inclusion constants of the solutes in pure water (K fw) were determined by extrapolation. The thermodynamic parameters (ΔH o and ΔS o) and dissociation constantsK am for the solutes in this chromatographic system were obtained by means of capacity factor (k) values using a corresponding model formulation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467195
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    Paper (German National Licenses)
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  • 3
    Electronic Resource
    Electronic Resource
    Analysis of organic pollutants in sewage by supercritical fluid extraction (1999)
    Springer
    Chromatographia 49 (1999), S. 399-405 
    Details
    ISSN: 1612-1112
    Keywords: Gas chromatography ; Solid phase adsorption ; Supercritical fluid extraction ; Sewage ; Organic pollutants
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Summary Analytical methods have been developed for the determination of organic pollutants of intermediate polarity in sewage. Water samples are first passed through a solid phase adsorption cartridge. The analytes are then extracted from the absorbent with supercritical CO2 into a small volume of trapping solvent. Finally, the extracts are analyzed directly by capillary gas chromatography and gas chromatography-mass spectrometer. The various parameters (pressure, temperature, type and concentration of modifiers, trapping solvent, flow rate and volume of supercritical fluid and equilibrium time) influencing the efficiency of extraction were studied. Extraction efficiencies for the test compounds are 〉70%, and relative standard deviations are 〈4.6% (n=3). The methods established were applied to the analysis of sewage at the Lanzhou Wastewater Treatment Plant, China. 66 organic pollutants were detected, of which 15 compounds appeared in the list of priority pollutants suggested by the US EPA.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02467613
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    Paper (German National Licenses)
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