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  • GEOPHYSICS  (7)
  • Nitrogen fixation  (3)
  • Apatite  (2)
  • 1
    Publication Date: 2011-08-19
    Description: Compact two-channel radiometers for solar occultation experiments have been constructed in order to measure stratospheric trace gases. The instruments can be used as filter- or correlation-type radiometers, depending on the trace gas under investigation. Within the LIMS correlative measurement program, balloon flights were performed with a payload of up to four of these two-channel radiometers. From the filter-type measurements, profiles of the trace gases H2O and HNO3 are inferred for the height region between the tropopause and the balloon float level. The data evaluation also includes a comprehensive analysis of the error sources and their effect on the accuracy of the trace gas profiles. The derived H2O and HNO3 profiles are assessed against the observations of other authors and are discussed in the light of the trace gas distributions calcualted from photochemical models.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 20; 3831-384
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  • 2
    Publication Date: 2011-08-18
    Keywords: GEOPHYSICS
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  • 3
    Publication Date: 2011-08-18
    Description: The Limb Infrared Monitor of the Stratosphere (LIMS) instrument on the Nimbus 7 spacecraft sensed limb emission profiles for 7 months, starting in October 1979. Vertical temperature profiles are inferred from measurements in two CO2 channels, and constituent profiles are obtained form the O3, HNO3, NO2, and water vapor channels. The line parameters used to calculate transmittances in the retrieval algorithm are presented. Their adequacy for LIMS and for other applications are assessed, and recommendations for future investigations are outlined.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 5141-514
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  • 4
    Publication Date: 2019-06-28
    Description: In the LIMS experiment using thermal IR limb scanning to sound the composition and structure of the upper atmosphere, one of the LIMS channels was spectrally centered at 6.9 micrometers to measure the vertical profile and global distribution of stratospheric water vapor. This channel's characteristics, the data from it, and the steps taken to validate results are described. The mean difference between the LIMS measurements and data from 13 balloon underflights is about 0.6 ppmv with LIMS mixing ratios biased high; this difference is of about the same order as estimated LIMS accuracy and less than the sum of the errors for LIMS and the balloon techniques. In-orbit precision is 0.2-0.3 ppmv and accuracy is estimated at 20-30 percent from 50 mbar to the stratopause. An unexplained diurnal variation exists in the vertical profile data which is largest at the 1-mbar level and virtually nonexistent at 10 mbar; day values are higher than night. More confidence is placed in zonal mean distributions averaged over several days than in single profiles. A zonal mean pressure-latitude cross section is described for January 5-9, 1979.
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 5115-512
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  • 5
    Publication Date: 2019-06-28
    Keywords: GEOPHYSICS
    Type: Journal of Geophysical Research (ISSN 0148-0227); 89; 5179-519
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  • 6
    Publication Date: 2019-06-28
    Description: The validation of results from the nitrogen dioxide channel and the quality of the data are examined in connection with the LIMS experiment which ran from late October 1978 to late May 1979. Factors studied include: channel characteristics, experiment errors due to instrument and spacecraft effects, predicted and measured precision, predicted accuracy, and comparisons with correlative measurements made in a series of balloon underflights. Features such as profile shape and slope of the mixing ratio altitude distribution are in good agreement. The LIMS data also fall within the range of previous mixing ratio measurements and are consistent with model estimates. The calculated on-orbit precision is about 0.3 ppbv and the estimated accuracy from simulations is about 2 ppbv over the 3-10-mbar range. Accuracy is less at higher and lower pressure levels. These results provide the first day-night set of nitrogen dioxide measurements from space.
    Keywords: GEOPHYSICS
    Type: ONERA, TP NO. 1984-166 , Journal of Geophysical Research (ISSN 0148-0227); 89; 5099-510
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  • 7
    Publication Date: 2019-08-27
    Description: Total odd nitrogen, NO(y), may be defined as the sum of all active nitrogen species that interchange photochemically with one another on a time scale of the order of weeks or less. As noted, NO + NO2 reactions dominate the processes controlling the ozone balance in the contemporary stratosphere. The observational data from non-satellite platforms are reviewed. The growth in available satellite data in the past four years is considered. Some of the most important scientific issues are discussed, taking into account new results from atmospheric models (mainly 2-D). The model results are compared with the observational data.
    Keywords: GEOPHYSICS
    Type: Atmospheric Ozone 1985. Assessment of our Understanding of the Processes Controlling its Present Distribution and Change, Volume 2; 110 p
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  • 8
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 3 (1969), S. 348-357 
    ISSN: 1432-0827
    Keywords: Inhibitors ; Nucleation ; Apatite ; Collagen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Des ions de Mg, Sr et F sont inhibitoires pour la formation de l'apatite quand on les ajoute à un tampon de calcification, séparément ou en combinaisons. La précipitation de l'apatite causée par des cristaux d'apatite est moins sensible à l'action inhibitrice que la nucléation spontanée et que la précipitation catalysée par la collagène d'os de mouton. La précipitation spontanée ou catalysée sont approximativement aussi sensibles. L'inhibition par des combinaisons de Mg avec des ions de Sr ou de F est additive. Ces résultats montrent que ces inhibiteurs ont acucune action spécifique sur la catalysation par la collagène de l'os de mouton qui soit différente de celle sur la nucléation de l'apatite en soi.
    Abstract: Zusammenfassung Mg, Sr und F Ionen hemmten die Fällung von Apatit wenn sie zu einem Calciumphosphatpuffer einzeln oder zusammen hinzugefügt wurden. Die Fällung von Apatit durch Apatitkeime war weniger empfindlich hinsichtlich der Hemmung als die spontane Nucleation und als die Fällung von Apatit, welche von Schafsknochenkollagen katalysiert werden kann. Die spontane und katalysierte Fällung sind ungefähr gleich empfindlich. Die Hemmung von Mg in Kombination mit Sr oder F Ionen war additiv. Diese Resultate weisen darauf hin, daß keine spezifischen Effekte bei der Katalyse von Knochenkollagen vorliegen, welche von den Effekten bei der Nucleation von Apatit an sich verschieden sind.
    Notes: Abstract Mg, Sr and F ions acted as inhibitors of apatite formation when added to a calcification buffer separately or in combinations. The precipitation of apatite under the influence of apatite seeds was less susceptible to inhibition than were spontaneous nucleation and apatite formation catalyzed by sheep bone collagen, while the latter two were about equally susceptible. Combinations of Mg with Sr or F ions showed additive effects. These results suggest that no specific effects of these inhibitors occurred on the catalytic action of the bone collagen different from their effects on the nucleation of apatite as such.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0014-5793
    Keywords: (Bradyrhizobium japonicum) ; Gene regulation ; Nitrogen fixation ; Protein, NifA ; Site-directed mutagenesis
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Springer
    Calcified tissue international 2 (1968), S. 343-352 
    ISSN: 1432-0827
    Keywords: Nucleation ; Mineralization ; Bone ; Collagen ; Apatite
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Medicine , Physics
    Description / Table of Contents: Résumé Nous avons utilisé de la collagène d'os de mounton et de tendons de queues de rats et des cristaux d'apatite pour étudier dans un système modèle la catalysation de la nucléation et la déposition de minéral dans un tampon métastabile. La collagène d'os de mouton se trouvait être un bon catalysateur, tandis que des expériences antérieures ont démontré que la collagène de tendons de queues de rats était un catalysateur très faible. Le phase rapide de la déposition de l'apatite dans la collagène se termine aussitôt que le contenu du minéral a attaint au plus 50 à 60 pour cent, bien que la supersaturation du tampon est encore bien èlevée. Les résultats montrent que dans un tel système modèle la quantité du depôt minéral est réglée par des facteurs semblables à ceux qui opèrent pendant la calcification biologique.
    Abstract: Zusammenfassung Kollagen aus Schafsknochen und Rattenschwanzsehnen und Apatitkeime wurden verwendet in einem Modell-System zur Untersuchung der katalytischen Nukleation und der Fällung von Mineral in einem metastabilen Calciumphosphatpuffer. Kollagen aus Schafsknochen war ein guter Katalysator für die Nukleation, während in früheren Versuchen sich herausstellte, daß Rattenschwanzkollagen ein ganz schlechter Katalysator ist. Die schnelle Phase der Apatitfällung im Kollagen war beendet, wenn der Mineralgehalt bis zu 50–60% angestiegen war, obwohl der Puffer noch stark übersättigt war. Die Resultate weisen daraufhin, daß die Menge des gefällten Minerals in einem solchen Modell-System von ähnlichen Faktoren reguliert wird wie die biologische Verkalkung.
    Notes: Abstract Sheep bone collagen, rat tail tendon collagen and apatite seeds were used in a model system to study nucleation catalysis and mineral deposition in a metastable calcification buffer. Sheep bone collagen was shown to be a good nucleation catalyst, while earlier experiments have shown that rat tail tendon collagen was a very poor catalyst. The rapid phase of apatite deposition in the collagen was terminated as soon as a mineral content of not more than 50–60 per cent was reached, although the buffer was still highly supersaturated. The results suggest that the amount of mineral deposited in such a model system is regulated by factors similar to those operating in biological calcification.
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