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  • 1
    Electronic Resource
    Electronic Resource
    Isolation and Characterisation of (5R, 6S,5′R,8′R)- and (5R,6S,5′R,8′S)-Luteochrome from Brazilian Sweet Potatoes (Ipomoea batatas LAM.) (1986)
    New York, NY : Wiley-Blackwell
    Helvetica Chimica Acta 69 (1986), S. 1554-1558 
    Details
    ISSN: 0018-019X
    Keywords: Chemistry ; Organic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Luteochrome isolated from the tubers of a white-fleshed variety of sweet potato (Ipomoea batatas LAM.) has been shown by HPLC, 1H-NMR and CD spectra to consist of a mixture of (5R,6S,5′R,8′R)- and (5R,6S,5′R,8′S)- 5,6:5′,8′-diepoxy-5,6,5′,8′-tetrahydro-β,β-carotene (1 and 2, resp.). Therefore, its precursor is (5R,6S,5′R,6′S)-5,6:5′,6′-diepoxy-5,6,5′,6′-tetrahydro-β,β-carotene (4). This is the first identification of luteochrome as a naturally occurring carotenoid and, at the same time, gives the first clue to the as yet unknown chirality of the widespread β,β-carotene diepoxide. These facts demonstrate that the enzymic epoxidation of the β-end group occurs from the α-side, irrespective of the presence of OH groups on the ring.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/hlca.19860690705
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  • 2
    Electronic Resource
    Electronic Resource
    Short fiber-reinforced thermoplastic elastomers from blends of natural rubber and polyethylene (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 5123-5146 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Thermoplastic elastomer blends of natural rubber (NR) with high density polyethylene (HDPE) and with low density polyethylene (LDPE) were reinforced with short silk fiber. Processing characteristics such as torque and temperature developed during mixing and the effect of processing parameters such as nip gap and number of passes in the mill necessary to secure maximum orientation of the fibers in the blends were studied. A small nip gap and a single pass in the mill were found to give best results. Of the different mixing sequences studied, the sequence where short fibers followed by rubber were added to the molten thermoplastic was found to give a uniform dispersion of fibers. Fiber breakage and the change in aspect ratio of the fibers after mixing were also examined. It was observed that, as a direct consequence of the mixing sequence, each fiber was coated with a layer of thermoplastic. Although the properties improved on the addition of the dry bonding system of silica-resorcinol-hexamethylenetetramine, the comparatively long curing time required for full development of adhesion between the fibers and the matrix proved to be a major disadvantage associated with the incorporation of the bonding system. The tensile and tear properties were substantially enhanced, but the ultimate elongation decreased sharply with increasing loading of short fibers in the blends. The effect of fiber orientation and the development of anisotropy in the properties was also noted. Scanning electron microscopy (SEM) studies of the benzene-extracted surfaces of the NR/HDPE (high density polyethylene) blends substantiated the theory of fibers behaving like “mechanical anchors” between the rubber and thermoplastic phase. The effect of fiber loading on the tear and tensile properties of the blends of NR/LDPE with varying blend ratios was studied. Most pronounced improvement in the properties on the addition of short fibers was observed in the high rubber blends. As the plastic content in the blends increased, the short fibers were found to have a lesser influence on the properties. SEM photomicrographs of the tensile and tear fracture surfaces indicated the fiber orientations and the effect of orientation, fiber loading, and blend ratios on the nature of fracture.
    Additional Material: 31 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320530
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  • 3
    Electronic Resource
    Electronic Resource
    Aromatic polyisophthalamides with oxybenzoyl pendent groups (1986)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part A: Polymer Chemistry 24 (1986), S. 483-493 
    Details
    ISSN: 0887-624X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A series of polyisophthalamides containing pendent oxybenzoyl groups were prepared from 5-oxybenzoyl-isophthaloyl chloride and aromatic diamines. The analogous unsubstituted polyisophthalamides were also prepared in order to compare the two series and to determine the effect of oxybenzoyl pendent groups on the properties of aromatic polyamides. The modified polymers exhibited better solubility than, and approximately the same glass transition temperatures (in the range 260-290°C) as, the parent unsubstituted polymers. The mechanical strength of polymer films was affected only to a small extent by the presence of side groups, but the thermal resistance was negatively affected, with the result that polyisophthalamides with oxybenzoyl pendent groups began to decompose at about 360°C (TGA), 60-100°C lower than the unsubstituted polyisophthalamides. By means of an appropriate thermal treatment, crosslinking of the modified polymers was achieved and their thermal resistance significantly enhanced.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pola.1986.080240307
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  • 4
    Electronic Resource
    Electronic Resource
    Deactivation with silazanes in chromatography, mechanism of the reaction and practical consequences in capillary GC and RP-HPLC: A29Si CP-MAS NMR study (1986)
    Weinheim : Wiley-Blackwell
    Journal of High Resolution Chromatography 9 (1986), S. 741-746 
    Details
    ISSN: 0935-6304
    Keywords: Capillary GC ; RP-HPLC ; CP-MAS NMR ; Deactivation methods ; Hexamethyldisilazane ; Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The reaction of Cab-O-Sil, a highly dispersed vitreous quartz, with hexamethyldisilazane (HMDS) was studied in the temperature range 380-500°C, using 29Si solid state NMR and other techniques. Such studies are of importance in view of deactivation procedures of fused silica at high temperatures in capillary GC.The commonly accepted reaction equation: \documentclass{article}\pagestyle{empty}\begin{document}$$ \left({{\rm Me}_{\rm 3} {\rm Si}} \right)_2 {\rm NH } + {\rm 2}\equiv {\rm SiOH} \to {\rm 2} \equiv {\rm SiOSiMe}_{\rm 2} + {\rm NH}_{\rm 3} $$\end{document} predominates only below ca. 400°C. Above ca. 400°C the intermediate cleavage product Me3SiNH2 reacts with surface silanol groups to form ≡SioSiMe2NH2 + CH4. At higher temperatures these groups may ultimately form (≡SiO)3SiNH2 groups (analogously to the formation of bi-and tridentate linkages starting from ≡SiOSiMe3 groups), but (≡SiO)3SiNH2 groups are also directly formed at lower temperatures, simultaneously with the ≡SiOSiMe3 groups, probably by reaction with siloxane bridges: \documentclass{article}\pagestyle{empty}\begin{document}$$ {\rm Me}_3 {\rm SiNH}_2 + \equiv {\rm SiOSi} \equiv\; \to \;\equiv SiNH_2 + \equiv SiOSiMe_3 $$\end{document}.The reactions of the trimethylsilylamine part of HMDS with Cab-O-Sil were confirmed by an independent series of silylations using N,N-dimethyltrimethylsilylamine instead of HDMS. The presence of amino groups as ≡SiNH2 was confirmed by FT-IR. This may be one of the reasons why very high temperature silylation with disilazanes does not provide a satisfactory deactivation of fused silica GC columns: the active ≡SiOH groups are “replaced” by active ≡SiNH2 groups. However, such a material may be of interest in LC. Silylation with silazanes at ca. 350°C in humid atmosphere and/or after extensive hydroxylation (leaching) of the surface should yield sufficiently deactivated surfaces with a rather well defined surface structure.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/jhrc.1240091206
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  • 5
    Electronic Resource
    Electronic Resource
    Tensile failure of γ-ray irradiated blends of high-density polyethylene and natural rubber (1986)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 4169-4183 
    Details
    ISSN: 0021-8995
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: The effect of 60Co γ-radiation on the tensile properties of thermoplastic elastomer blends of natural rubber (NR) and high-density polyethylene (HDPE) has been investigated. The samples were irradiated to absorbed doses ranging from 0.1 to 100 Mrad in air at room temperature (25°C) at a dose rate of 0.21 Mrad/hr. The effect of blend ratio and addition of carbon black (N 330) dicumyl peroxide (DCP) on the radiation resistance of the blends has also been studied. High energy radiation at a high dose rate was found to cause extensive crosslinking in the bulk, which in effect, caused a minima in the ultimate tensile strength in the range of 10-25 Mrad and a continuous decline in the elongation at break in all the blends. Chain scission, on the other hand, was restricted to the surface under the above-mentioned experimental conditions. This contention was substantiated by the results of irradiation of the samples in a nitrogen environment. Scanning electron microscopy (SEM) studies on the tensile fracture surface morphology of the blends have also been undertaken in order to gain insight to the mechanism of failure.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1986.070320330
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  • 6
    Electronic Resource
    Electronic Resource
    Crosslinkable copolyisophthalamides (1986)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 139 (1986), S. 113-122 
    Details
    ISSN: 0003-3146
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Copolyamide mit Nadimidseitengruppen wurden durch Polykondensation von 5-(5-Norbornen-2,3-dicarboximido)-isophthaloylchlorid (NCIC) und Isophthaloylchlorid mit Bis(4-aminophenyl)-methan hergestellt, wobei die verwendeten Verhältnisse der beiden Dicarbonsäurechloride 0/100, 10/90, 15/85, 20/80, 25/75, 50/50 und 100/0 betrugen. Durch 1H-NMR Untersuchung wurde festgestellt, daß die Zusammensetzung der entstehenden Copolyamide mit der der ursprünglichen Monomermischungen übereinstimmte.Die Eigenschaften der Copolyamide, wie Löslichkeit, Glasübergangstemperatur und thermische Beständigkeit, wurden gemessen und bezüglich der Zusammensetzungen interpretiert. Die Vernetzung der Copolymeren wurde mittels DSC studiert und ein Vergleich ihrer Eigenschaften vor und nach der thermischen Vernetzung durchgeführt.Der Einfluß der Vernetzung auf die mechanischen Eigenschaften der Copolyamidfolien wurde ebenfalls gemessen.
    Notes: Copolyisophthalamides with nadimide pendent groups have been prepared by polycondensation of 5(5-norbornene-2,3-dicarboximido)isophthaloyl chloride (NCIC) and isophthaloyl chloride with bis(4-aminophenyl)methane, the ratio between both diacid chlorides being 0/100, 10/90, 15/85, 20/80, 25/75, 50/50, and 100/0. By 1H-NMR it has been proved that the composition of the copolymers closely coincided with the ratio of monomer's feeds.Properties such as solubility, glass transition temperatures, and thermal resistance have been measured and related to the copolymer's composition. Crosslinking studies have been carried out by DSC, and a comparison of properties of copolymers before and after thermal crosslinking has been made. The effect of crosslinking on the mechanical strength of copolymer films has also been measured.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1986.051390111
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  • 7
    Electronic Resource
    Electronic Resource
    1H NMR study and conformational aspects of 20′-deoxy-20′-epivindesine (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 35-40 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The 1H NMR spectrum of 20′-deoxy-20′-epivindesine has been unravelled at 500 MHz. COSY and 2D NOESY experiments were used. The conformational features are assigned.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260240109
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  • 8
    Electronic Resource
    Electronic Resource
    A 13C NMR investigation of [5]metacyclophanes (1986)
    Chichester : Wiley-Blackwell
    Organic Magnetic Resonance 24 (1986), S. 308-311 
    Details
    ISSN: 0749-1581
    Keywords: Chemistry ; Analytical Chemistry and Spectroscopy
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Carbon-13 NMR data of [5]metacyclophane (1a), its 8,11-dihalosubstituted derivatives 1b-1d and of some model compounds are reported and discussed. A remarkable downfield shift is observed for the aromatic carbon between the bridging carbons; this is tentatively ascribed to long-range effects of the bridge and to the bending of the aromatic ring.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/mrc.1260240408
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  • 9
    Electronic Resource
    Electronic Resource
    Evidence for a folded structure of met-enkephalin in membrane mimetic systems: 1H-nmr studies in sodiumdodecylsulfate, lyso-phosphatidylcholine, and mixed lyso-phosphatidylcholine/sulfatide micelles (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 2315-2323 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: 1H-nmr spectra of Met-enkephalin dissolved in aqueous solution of sodiumdodecylsulfate (SDS) micelles are reported as a function of pH and temperature. The temperature behavior of the amide protons is compared with that observed for the same peptide dissolved in aqueous solution of lyso-phosphatidylcholine (LPC) and lyso-phosphatidylcholine-sulfatide (LPC-SH) micelles. The temperature coefficients are affected by the micelle polarity, which suggests that the peptide backbone is not remote from the micelle surface. pH titration performed in the presence of SDS micelles gives a number of intrinsic and extrinsic pKa values, indicative of a folded structure of the opioid molecule. This conformation is characterized by the existence of an intramolecular hydrogen bond involving the Met-5 amide proton and an interaction of the N-terminal residue with the aliphatic side chains of both Phe-4 and Met-5.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360251209
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  • 10
    Electronic Resource
    Electronic Resource
    Structural investigation of poly-L,D-proline, a synthetic ion channel across bilayer membranes: Crystal structure and molecular conformation of two tetra-D,L-proline derivatives (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 2227-2236 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The crystal structures and molecular conformations of two tetraproline derivatives with alternating configurations Boc(D-Pro,L-Pro)2OH and Boc(D-Pro,L-Pro)2OCH3 are investigated in connection with the ability of the homologous polymer to selectively increase (as an ion channel) the ion permeability across bilayer membranes. Both tetramers are characterized by the cis-trans alternating conformation of the peptide bonds, which formally transforms in a turn of the poly-D,L-proline channel after a cis-trans change of the central peptide residue.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360251202
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