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  • DSC  (2)
  • Ras-binding domain  (2)
  • UV/VIS spectroscopy  (2)
  • Springer  (6)
  • American Meteorological Society (AMS)
  • Berlin: Deutsches Institut für Wirtschaftsforschung (DIW)
Collection
Publisher
  • Springer  (6)
  • American Meteorological Society (AMS)
  • Berlin: Deutsches Institut für Wirtschaftsforschung (DIW)
Years
  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Biogeochemistry 47 (1999), S. 219-238 
    ISSN: 1573-515X
    Keywords: dissolved humic substances ; FTIR spectroscopy ; land use history ; peat ; synchronous fluorescence spectroscopy ; UV/VIS spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The elemental composition and spectroscopic properties of dissolved fulvic acids isolated from different sampling media (topsoil, ground and surface water) of a natural fen area (high portion of organic soils) were examined to reveal the effects of land use history. These effects need to be known if dissolved humic substances are to be a major factor in identifying the impact of present and future changes in land use. Dissolved fulvic acids (topsoil, groundwater) from highly degraded peatlands (due to a long-term agricultural use) exhibit lower C/N ratios, higher absorption in the UV spectra, and higher absorption at 1,620 cm−1 in the FTIR spectra compared with fulvic acids from relatively intact peatlands. These properties illustrate that long-term agricultural use with high inputs results in increased aromatic structures and a further humification of dissolved fulvic acids due to very strong peat decomposition compared with relatively intact peatlands. Synchronous fluorescence spectra also indicate the higher level of aromatic structures within fulvic acids isolated from sites with long-term agricultural use (high peat decomposition) compared with a land use history resulting in a lower peat decomposition. The different sources of fulvic acids in surface water (precipitation, runoff, interflow, groundwater) are the main reason for these effects not being detected in fulvic acids isolated from surface water. Short-term changes in land use characterized by a transition from crop farming to an unimproved grassland were found not to affect the spectroscopic properties of dissolved fulvic acids. A humification index deduced from the synchronous fluorescence spectra is proposed. We have strong evidence that dissolved humic substances indicate changes in the environmental conditions (both anthropogenic and natural) of wetlands with a high proportion of organic soils.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    Biogeochemistry 47 (1999), S. 219-238 
    ISSN: 1573-515X
    Keywords: dissolved humic substances ; FTIR spectroscopy ; land use history ; peat ; synchronous fluorescence spectroscopy ; UV/VIS spectroscopy
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Geosciences
    Notes: Abstract The elemental composition and spectroscopic properties of dissolved fulvic acids isolated from different sampling media (topsoil, ground and surface water) of a natural fen area (high portion of organic soils) were examined to reveal the effects of land use history. These effects need to be known if dissolved humic substances are to be a major factor in identifying the impact of present and future changes in land use. Dissolved fulvic acids (topsoil, groundwater) from highly degraded peatlands (due to a long-term agricultural use) exhibit lower C/N ratios, higher absorption in the UV spectra, and higher absorption at 1,620 cm−1 in the FTIR spectra compared with fulvic acids from relatively intact peatlands. These properties illustrate that long-term agricultural use with high inputs results in increased aromatic structures and a further humification of dissolved fulvic acids due to very strong peat decomposition compared with relatively intact peatlands. Synchronous fluorescence spectra also indicate the higher level of aromatic structures within fulvic acids isolated from sites with long-term agricultural use (high peat decomposition) compared with a land use history resulting in a lower peat decomposition. The different sources of fulvic acids in surface water (precipitation, runoff, interflow, groundwater) are the main reason for these effects not being detected in fulvic acids isolated from surface water. Short-term changes in land use characterized by a transition from crop farming to an unimproved grassland were found not to affect the spectroscopic properties of dissolved fulvic acids. A humification index deduced from the synchronous fluorescence spectra is proposed. We have strong evidence that dissolved humic substances indicate changes in the environmental conditions (both anthropogenic and natural) of wetlands with a high proportion of organic soils.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 38 (1992), S. 277-287 
    ISSN: 1572-8943
    Keywords: DSC ; limit of detection ; polymorphic transitions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Zusammenfassung Anhand von sehr kleinen Signalen von spontanen polymorphen übergängen bei CsCl, K2Cr2O7 und Na2SO4 wird ein Verfahren zur Bestimmung der Nachweisgrenze von DSC-Geräten beschrieben. Es wird gezeigt, wie derartige Signale gut aufgelöst in DSC-Diagrammen von Pulverproben erhalten werden können. Um sie vom Rauschen der Basislinie zu unterscheiden, sollten sie eine Höhe von mindestens dem Doppelten der Basislinienbreite aufweisen. Für das angewendete Gerät beträgt die entsprechende geringste Wärmemenge, d.h. die Nachweisgrenze 0.1 mJ.
    Notes: Abstract A procedure is described to determine the limit of detection of DSC instruments by using tiny signals from spontaneous polymorphic transitions of CsCl, K2Cr2O7 and Na2SO4. It is shown how such signals can be found well-resolved in DSC diagrams of powder samples. To distinguish them from the baseline noise they should exhibit a height at least twice that of the baseline width. For the instrument employed the corresponding smallest amount of heat, i.e., the limit of detection, was found to be 0.1 mJ.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Springer
    Journal of thermal analysis and calorimetry 52 (1998), S. 145-155 
    ISSN: 1572-8943
    Keywords: acrylates ; DMA ; DSC ; epoxides ; radiation curing ; structure-property relationship ; TG ; thermal analysis
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Thermo-oxidative and thermo-mechanical stabilities of radiation-cured acrylates and epoxides were examined by TG, DMA and DSC. The polymeric trifunctional acrylates PETIA, TMPTA and THEIC displayed the highest temperatures of onset of degradation. The high crosslinking density of the films resulted in an almost temperature-independent complex E-modulus, as measured by DMA. With increasing degree of ethoxylation or propoxylation of the monomers, decreases in thermal stability and strength were found. For difunctional polymeric acrylates and epoxides, the glass transition temperature was measured. The average degree of curing of UV-cured epoxy films can be determined from the temperature of the maximum in the loss modulus (E″max.
    Type of Medium: Electronic Resource
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  • 5
    ISSN: 1573-5001
    Keywords: Byr2 ; Ras-binding domain ; sequential assignment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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  • 6
    ISSN: 1573-5001
    Keywords: AF6 ; NMR assignment ; Ras-binding domain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Chemistry and Pharmacology
    Type of Medium: Electronic Resource
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