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  • Copernicus  (2)
  • Wiley-Blackwell  (2)
  • 1
    Electronic Resource
    Electronic Resource
    Reaktionsmechanismus und Strukturänderungen beim enzymatischen Abbau von Cellulose durch Trichoderma-reesei-CellulaseHerrn Professor Dr. habil. Burkart Philipp zum 60. Geburtstag gewidmet (1985)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 36 (1985), S. 76-80 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: A bleached spruce sulfite pulp is degraded by means of cellulase from T. reesei. During the reaction, degree of polymerization, crystallinity and void volume of the residue are studied. Only very minor changes are found. Furthermore, the molecular mass and hydrodynamic radius of the total enzyme, of its C1-fraction, and of the residual enzyme are determined. The enzyme molecule is considerably larger than the channels leading into the interior of cellulose. Therefore, a reaction mechanism of the “all or nothing” type is suggested.
    Notes: Ein gebleichter Fichtensulfitzellstoff wird mit Cellulase aus T. reesei abgebaut. Während der Reaktion werden Polymerisationsgrad, Kristallinität und Hohlraumvolumen des Rückstandes untersucht. Es werden nur sehr geringfügige Änderungen gefunden. Weiter werden am Gesamtenzym, einer daraus isolierten C1-Fraktion sowie dem Restenzym Molekülmasse und hydrodynamischer Radius bestimmt. Das Enzym-Molekül ist wesentlich größer als die Kanäle, die in das Innere der Cellulose führen. Es wird daher ein Reaktionsmechanismus vom „alles oder nichts“ -Typ vorgeschlagen.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1985.010360204
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  • 2
    Electronic Resource
    Electronic Resource
    Structural changes of LODP cellulose in the original and mercerized state during enzymatic hydrolysis (1992)
    Weinheim : Wiley-Blackwell
    Acta Polymerica 43 (1992), S. 270-274 
    Details
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Die während der enzymatischen Hydrolyse unterschiedlicher Cellulosepräparate auftretenden Strukturveränderungen wurden mittels Röntgen-Kleinwinkel- und -Weitwinkelstreuung, Bestimmung des Wasserrückhaltevermögens und DP-Messung untersucht. Dazu wurden LODP-Proben im ursprünglichen (Cellulose I) und im mercerisierten (Cellulose II) Zustand mit einem kommerziellen Cellulosepräparat von Trichoderma reesei abgebaut. Die Mercerisierung des Cellulose I-Pulvers führt zu einem bemerkenswerten Anstieg der Abbaubarkeit infolge einer mehr feindispersen Hohlraumstruktur und damit einer deutlich höheren spezifischen inneren Oberfläche der Cellulose II-Probe. Basierend auf der Änderung von Kristallinitätsgrad, lateraler und longitudinaler Kristallitgröße und des DP nach unterschiedlich langer Hydrolyse wurde auf einen übermolekularen Abbaumechanismus nach dem Prinzip “Alles oder Nichts” für die Ketten der Cellulose I geschlossen, während für Cellulose II in den kristallinen Bereichen ein allmählicher Abbau von den Kettenenden her angenommen wird.
    Notes: The structural changes during enzymatic hydrolysis of cellulose substrates were studied by SAXS, WAXS, water retention values, and degree of polymerization. LODP cellulose samples in original (cellulose I) and mercerized (cellulose II) form were hydrolyzed using a commercial cellulase preparation produced by the fungus Trichoderma reesei. The mercerization of the LODP-cellulose I powder results in a remarkable increase in degradability due to a more finely dispersed void structure with a distinct higher specific inner surface of the cellulose II. Based on the course of the degree of crystallinity, lateral and longitudinal crystallite sizes, and the DP at different stages of degradation a supermolecular mechanism of the “all or nothing” type was found for the chains in LOPD-cellulose I, whereas for cellulose II an endwise degradation of ordered regions has been concluded.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/actp.1992.010430506
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  • 3
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    Analysing spatio-temporal patterns of the global NO2-distribution retrieved from GOME satellite observations using a generalized additive model (2009)
    Copernicus
    Details
    Publication Date: 2009-04-09
    Description: With the increasing availability of observations from different space-borne sensors, the joint analysis of observational data from multiple sources becomes more and more attractive. For such an analysis – oftentimes with little prior knowledge about local and global interactions between the different observational variables available – an explorative data-driven analysis of the remote sensing data may be of particular relevance. In the present work we used generalized additive models (GAM) in this task, in an exemplary study of spatio-temporal patterns in the tropospheric NO2-distribution derived from GOME satellite observations (1996 to 2001) at global scale. We modelled different temporal trends in the time series of the observed NO2, but focused on identifying correlations between NO2 and local wind fields. Here, our nonparametric modelling approach had several advantages over standard parametric models: While the model-based analysis allowed to test predefined hypotheses (assuming, for example, sinusoidal seasonal trends) only, the GAM allowed to learn functional relations between different observational variables directly from the data. This was of particular interest in the present task, as little was known about relations between the observed NO2 distribution and transport processes by local wind fields, and the formulation of general functional relationships to be tested remained difficult. We found the observed temporal trends – weekly, seasonal and linear changes – to be in overall good agreement with previous studies and alternative ways of data analysis. However, NO2 observations showed to be affected by wind-dominated processes over several areas, world wide. Here we were able to estimate the extent of areas affected by specific NO2 emission sources, and to highlight likely atmospheric transport pathways. Overall, using a nonparametric model provided favourable means for a rapid inspection of this large spatio-temporal data set,with less bias than parametric approaches, and allowing to visualize dynamical processes of the NO2 distribution at a global scale.
    Electronic ISSN: 1680-7375
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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  • 4
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    Analysing spatio-temporal patterns of the global NO2-distribution retrieved from GOME satellite observations using a generalized additive model (2009)
    Copernicus
    Details
    Publication Date: 2009-09-08
    Description: With the increasing availability of observational data from different sources at a global level, joint analysis of these data is becoming especially attractive. For such an analysis – oftentimes with little prior knowledge about local and global interactions between the different observational variables at hand – an exploratory, data-driven analysis of the data may be of particular relevance. In the present work we used generalized additive models (GAM) in an exemplary study of spatio-temporal patterns in the tropospheric NO2-distribution derived from GOME satellite observations (1996 to 2001) at global scale. We focused on identifying correlations between NO2 and local wind fields, a quantity which is of particular interest in the analysis of spatio-temporal interactions. Formulating general functional, parametric relationships between the observed NO2 distribution and local wind fields, however, is difficult – if not impossible. So, rather than following a model-based analysis testing the data for predefined hypotheses (assuming, for example, sinusoidal seasonal trends), we used a GAM with non-parametric model terms to learn this functional relationship between NO2 and wind directly from the data. The NO2 observations showed to be affected by wind-dominated processes over large areas. We estimated the extent of areas affected by specific NO2 emission sources, and were able to highlight likely atmospheric transport "pathways". General temporal trends which were also part of our model – weekly, seasonal and linear changes – showed to be in good agreement with previous studies and alternative ways of analysing the time series. Overall, using a non-parametric model provided favorable means for a rapid inspection of this large spatio-temporal NO2 data set, with less bias than parametric approaches, and allowing to visualize dynamical processes of the NO2 distribution at a global scale.
    Print ISSN: 1680-7316
    Electronic ISSN: 1680-7324
    Topics: Geosciences
    Published by Copernicus on behalf of European Geosciences Union.
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