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  • 1980-1984  (8)
  • Inorganic Chemistry  (3)
  • Polymer and Materials Science  (3)
  • Water permeability  (2)
  • 1
    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
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  • 2
    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
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Acta Polymerica 34 (1983), S. 328-331 
    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: 2,2′-azo-bis-isobutyronitrile was completely thermally decomposed in allyl benzene. The reaction mixture obtained was separated by preparative gas and thin-layer chromatography. Using steam pressure measurements and the logarithmic dependence of gas chromatographic retention value of the molecular weight the molecular weight of the separated components was investigated. The structure was analysed by IR- and NMR-spectroscopy and 14C-labelled tracer substances. A mechanism of the reactions is discussed.
    Notes: 2,2′-Azo-bis-isobutyronitril wurde in Allylbenzen thermisch vollständig zersetzt. Das entstehende Reaktionsgemisch konnte mit Hilfe der präparativen Gas- und Dünnschichtchromatographie getrennt werden. Die Bestimmung der Molmassen der abgetrennten Komponenten erfolgte über Dampfdruckmessungen sowie über die logarithmische Abhängigkeit der gaschromatographischen Retentionswerte von den Molmassen. Die Konstitutions- und Konfigurationsaufklärung gelang mittels IR- und NMR-Spektroskopie sowie durch Anwendung von 14C-markierten Tracer-Substanzen. Ein möglicher Reaktionsablauf wird diskutiert.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0323-7648
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 3 Tab.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 473 (1981), S. 85-90 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Carbosilylated phospha-alkenesLithium-tris-trimethylsilylmethanide, (Me3Si)3C-Li, reacts with various organodichlorophosphines to give tris-(trimethylsilyl)-methyl-organochlorophosphines, the termal treatment of which under elimination of trimethylchlorosilane results in formation of the title compounds of the general formula B.NMR-data as well as the synthesis of compounds A and B will be discussed.
    Notes: Lithium-tris-trimethylsilylmethanid, (Me3Si)3C-Li, reagiert mit verschieden substituierten Organyldichlorphosphinen zur Tris-Trimethylsilylmethyl-organylchlorphosphinen A, deren thermische Beanspruchung unter Abspaltung von Trimethylchlorsilan zu den Titelverbindungen der allgemeinen Formel B führt.Die NMR-spektroskopischen Daten der Verbindungen des Typs A und B sowie deren Synthese wer-den diskntiert.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 488 (1982), S. 75-79 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: 2,4,6-Tris(tert.butyl)phenyl Substituted PhosphinesTris(tert.butyl)phenyl-lithium reacts with PCl3 to give 2,4,6-tris(tert.butyl)phenyldihalogenophosphine which is reduced by LiAlH4 yielding 2,4,6-tris(tert.butyl)phenylphosphine. The same reaction by using (CH3)3Si—CH2—PCl2 leads to 2,4,6-tris(tert.butyl)phenyl-trimethylsilylmethylhalogenophosphine. Thermal treatment of this compound results under elimination of HCl and (CH3)3SiCl in the formation of . The nmr data of the compounds synthesized are discussed.
    Notes: Tris(tert.butyl)phenyl-lithium reagiert mit PCl3 oder (CH3)3Si—CH2—PCl2 zum 2,4,6-Tris(tert.butyl)phenyl-dihalogenphosphin bzw. entsprechenden -trimethylsilylmethylhalogenphosphin. Während sich ersteres mit LiAlH4 in das 2,4,6-Tris(tert.butyl)phenylphosphin überführen läßt, liefert letzteres durch thermische Beanspruchung nach Abspalten von HCl bzw. (CH3)3SiCl die Phosphine mit zweifach koordiniertem Phosphor. Die 1H- sowie 31P-NMR-Daten der dargestellten Verbindungen werden diskutiert.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 495 (1982), S. 115-119 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkali Phosphorus Compounds and their Reactivity. 79. NMR Investigations of Alkali Organophosphides. IThe 31C and 31P NMR spectra display a further separation of ion-pairs of alkali-organophosphides in THF solution after addition of cryptandes . An exception presents LiP(Ph)2, T1—13C-NMR measurements suggest a tetrameric structure in THF.
    Notes: Anhand der 13C- und 31P-NMR-Daten läßt sich zeigen, daß sich die Ionenpaare der Alkali-organophosphide in THF durch Zugabe von Kryptanden entsprechend weiter trennen lassen. Eine Ausnahme bildet LiP(Ph)2, das aufgrund von T1—13C-NMR-Messungen eine tetramere Struktur in THF aufweist.
    Additional Material: 2 Tab.
    Type of Medium: Electronic Resource
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  • 8
    Electronic Resource
    Electronic Resource
    Basel : Wiley-Blackwell
    Die Makromolekulare Chemie, Rapid Communications 3 (1982), S. 745-751 
    ISSN: 0173-2803
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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