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  • 1980-1984  (3)
  • 1975-1979
  • 1970-1974
  • 1920-1924
  • Water permeability  (2)
  • 13CO2-Gehalt der Atemluft  (1)
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Material
Years
  • 1980-1984  (3)
  • 1975-1979
  • 1970-1974
  • 1920-1924
Year
Keywords
  • 1
    Electronic Resource
    Electronic Resource
    Einfluß des natürlichen Isotopengehaltes von Nährstoffen auf den Untergrund bei13C-Atemtests (1983)
    Springer
    European journal of nutrition 22 (1983), S. 107-115 
    Details
    ISSN: 1436-6215
    Keywords: 13C-Atemtest ; natürlicher Isotopengehalt von Nahrungsmitteln ; 13CO2-Gehalt der Atemluft ; parenterale Ernährung
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The long-term variation of the mean δ13C-value of breath-CO2 of Europeans (base value −26‰) was ±1‰ over a period of several months. However, the ingestion of products from corn, a C4-plant, caused remarkably higher shifts. In a fasted state and during rest a stability of the base value of ±0.3‰ could be attained for several hours. Longer fasting periods imply a shift of the CO2-δ-value due to the metabolism of body products. — By a change of the main energy source to corn products the δ13C-base line could be shifted to −18‰ within one day. After this shift even the metabolism of products from C3-plants could be investigated. The degradation curve and the integral degradation of fats were largely dependent on the method of application, and the base value largely interfered with the results. The period of maximum disintegration for a naturally and uniformly labelled fat was different from that of an artificially labelled trilinoleate. The results shall be used for the adjustment and the correction of the base line in13C-breath tests, especially with patients under parenteral nutrition.
    Notes: Zusammenfassung Der mittlere δ13C-Wert im CO2 der Atemluft von Europäern (Basiswert −26‰) zeigt eine Langzeitschwankung über mehrere Monate von ±1,0‰; der Verzehr von Produkten aus C4-Pflanzen (z. B. Mais) hat allerdings erheblich höhere Änderungen zur Folge. Im Nüchternzustand und in Ruhe wird während 6 h eine Stabilität des Basiswertes von ±0,3‰ erreicht; nach längeren Nüchternphasen kann aber der Abbau körpereigener Substanzen zu Verschiebungen führen. Durch Umstellung der Energieversorgung auf Maisprodukte ist es möglich, den Basiswert innerhalb eines Tages auf −18‰ zu heben; dann läßt sich auch der Abbau von Substanzen aus C3-Pflanzen verfolgen. Der Verlauf und die Rate des Abbaues von markierten Fetten sind stark von der Art der Applikation abhängig, und die Messung des Gesamtumsatzes wird durch den Untergrund stark beeinträchtigt. Der Zeitpunkt des maximalen Abbaues von uniform markiertem Fett (Sojaöl) unterschied sich von dem eines in der Carboxylgruppe markierten Trilinoleats. Die Resultate sind Grundlage zur Einstellung bzw. Korrektur von Basiswerten bei13C-Atemtests, besonders bei Patienten mit parenteraler Ernährung.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02026207
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    Paper (German National Licenses)
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  • 2
    Electronic Resource
    Electronic Resource
    Fine structure of plant cuticles in relation to water permeability: The fine structure of the cuticle of Clivia miniata reg. leaves (1981)
    Springer
    Planta 152 (1981), S. 259-267 
    Details
    ISSN: 1432-2048
    Keywords: Clivia ; Cuticle development and fine structure ; Water permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure of the upper cuticular membrane (CM) of Clivia miniata leaves was investigated using electron microscopy. The CM is made up of a thin (130 nm) lamellated cuticle proper (CP) and a thick (up to 7 μm over periclinal walls) cuticular layer (CL) of marbled appearance. Evidence is presented to show that the electron lucent lamellae of the CP do not simply represent layers of soluble cuticular lipids (SCL). Instead, the lamellation is probably due to layers of cutin differing in polarity. It is argued that the SCL in the Cp are the main barrier to water. Thickening of the CM during leaf development takes place by interposition of cutin between the CM and the cellin wall. The cutin of young, expanding leaves has a high affinity for KMnO4 and is therefore relatively polar. As leaves mature, the external CL underneath the CP becomes non-polar, as only little contrast can be obtained with permanganate as the post fixative.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00385154
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  • 3
    Electronic Resource
    Electronic Resource
    Water permeability of periderm membranes isolated enzymatically from potato tubers (Solanum tuberosum L.) (1983)
    Springer
    Planta 158 (1983), S. 294-301 
    Details
    ISSN: 1432-2048
    Keywords: Periderm membranes ; Solanum, periderm ; Suberin ; Tuber ; Water permeability
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The fine structure and water permeability of potato tuber periderm have been studied. Periderm membranes (PM) were isolated enzymatically using pectinase and cellulase. They were composed of, about six layers of phellem cells arranged in radial rows. The walls of phellem cells consist of cellulosic primary and tertiary walls and suberized secondary walls which are lamellated. Middle lamellae and primary walls contain lignin. Since the PM did not disintegrate during enzymatic isolation it appears that lignin also extends into the secondary suberized walls. The water permeability of PM was low, ranging from 1–3·10-10 m s-1. This low water permeability developed only during storage of tubers in air. Periderm membranes from freshly harvested tubers had a relatively high permeability. The low permeability of PM from stored tubers is attributed to soluble lipids associated with suberin since: (1) extraction of soluble lipids from PM increased permeability by more than 100-fold, (2) a phase transition of soluble lipids was observed between 46 and 51° C, and (3) only the permeability of PM decreased during storage while the permeability of extracted PM remained unchanged. Evidence is presented that two pathways for water movement exist in parallel. Pathway 1 is represented by middle lamellae and primary walls extending in radial direction across the membranes. This pathway has a relatively high specific permeability. Pathway 2 is represented by a polylaminated structure made up of tangential walls of phellem cells which are orientated normal to the direction of water flow. This pathway has a low specific permeability because of the properties of secondary walls incrusted with soluble lipids. It is calculated that about 10% of the water flows across pathway 1 and 90% across pathway 2 which has a volume fraction of 0.995.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00397330
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    Paper (German National Licenses)
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