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  • 1
    Electronic Resource
    Electronic Resource
    Application of tomographic inversion in studying airglow in the mesopause region (1998)
    Springer
    Annales geophysicae 16 (1998), S. 1180-1189 
    Details
    ISSN: 0992-7689
    Keywords: Tomography ; Airglow ; Mesopause ; Gravity waves
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences , Physics
    Notes: Abstract It is pointed out that observations of periodic nightglow structures give excellent information on atmospheric gravity waves in the mesosphere and lower thermosphere. The periods, the horizontal wavelengths and the phase speeds of the waves can be determined from airglow images and, using several cameras, the approximate altitude of the luminous layer can also be determined by triangulation. In this paper the possibility of applying tomographic methods for reconstructing the airglow structures is investigated using numerical simulations. A ground-based chain of cameras is assumed, two-dimensional airglow models in the vertical plane above the chain are constructed, and simulated data are calculated by integrating the models along a great number of rays with different elevation angles for each camera. After addition of random noise, these data are then inverted to obtain reconstructions of the models. A tomographic analysis package originally designed for satellite radiotomography is used in the inversion. The package is based on a formulation of stochastic inversion which allows the input of a priori information to the solver in terms of regularization variances. The reconstruction is carried out in two stages. In the first inversion, constant regularization variances are used within a wide altitude range. The results are used in determining the approximate altitude range of the airglow structures. Then, in the second inversion, constant non-zero regularization variances are used inside this region and zero variances outside it. With this method reliable reconstructions of the models are obtained. The number of cameras as well as their separations are varied in order to find out the limitations of the method.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s00585-998-1180-9
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  • 2
    Electronic Resource
    Electronic Resource
    Pepsin immobilized on inorganic supports for the continuous coagulation of skim milk (1977)
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 19 (1977), S. 683-700 
    Details
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The milk-clotting enzyme pepsin was immobilized onto beads of alumina, titania, glass, stainless steel, iron oxide, and Teflon for treating skim milk in a fluidized-bed reactor. Two covalent attachment procedures using silanized supports and glutaraldehyde and two adsorption procedures were evaluated. The three best catalysts were titania and glass, using the covalent attachment procedure, and alumina, using the adsorption procedure at pH 1.2. The pepsin adsorbed on alumina catalyst has commercial potential compared to the previously used glass catalyst. Attempts to increase the stability of pepsin adsorbed on alumina by cross-linking with glutaraldehyde were unsuccessful owing to the low pH necessary for optimum pepsin adsorption. Desorption of pepsin from alumina during reactor operation was determined. Regeneration of spent catalysts was only partially successful.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bit.260190506
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  • 3
    Electronic Resource
    Electronic Resource
    The characterization of polystyrene oligomers by field-desorption mass spectrometry (1990)
    New York, NY : Wiley-Blackwell
    Rapid Communications in Mass Spectrometry 4 (1990), S. 355-359 
    Details
    ISSN: 0951-4198
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Field-desorption mass spectrometry has been used to characterize polystyrene oligomers of molecular weight up to 15 000 Da. The technique shows good agreement with molecular weight data calculated using vapour-phase osmometry and gel-permeation chromatography but in addition provides much more detailed information in terms of oligomer distribution and the nature of end groups present in the oligomers.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/rcm.1290040913
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