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  • Polymer and Materials Science  (29)
  • 1985-1989  (17)
  • 1975-1979  (12)
  • 1
    Electronic Resource
    Electronic Resource
    Some special aspects of thermal ageing of isotactic polypropylene (measuring method: Isothermal long-term DTA)Vortrag anläßlich des 18. Donauländergesprächs über “Natürliche und künstliche Alterung von Kunststoffen” in Villach (Österreich) vom 24.-26. Juni 1987. (1988)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 158 (1988), S. 321-334 
    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: An Folien (Dicke 100 pm) aus isotaktischem Polypropylen mit verschiedenen Antioxidansgehalten (0,0% bis 0,1%) wird die thermooxidative Alterunq mit der isothermen Langzeit-Differential-Thermo-Analyse (ILDTA) bis zu Temperaturen weit unter dem Kristallitschmelzbereich verfolqt und die Messwerte mit Ergebnissen aus dem Zeitstand-Zugversuch korreliert. Dabei zeigt sich, daß aus Messunqen mit der ILDTA bereits vor Einsetzen der autokatalytischen Zersetzunq sreaktion Ruckschlüsse auf die thermische Vorqeschichte der Proben und Aussagen auf das rnit einem Abfall der mechanischen Eigenschaften verbundene Ende der thermo-oxidativen Stabilität des Polymeren getroffen werden können.Weiters bietet die ILDTA die Moglichkeit, durch den direkten Zusamenhang zwischen Oxidationszeit und Antioxidansögehalt die örtliche Stabilisatorverteilung in Platten und in Folien zu bestimmen und damit Diffusionsvorqange zu verfolgen.
    Notes: Thermo-oxidative ageing processes were investigated in films (100 μm thick) made from isotactic polypropylene with different antioxidant concentrations between 0% and 0.1% using isothermal long-term differential thermal analysis (ILDTA). The end of the oven life of polypropylene coincided with the loss of mechanical properties which was confirmed by tensile tests at temperatures far below the crystallite melting range. Already prior to the beginning of autocatalytic decomposition, ILDTA experiments permits conclusions to be drawn on the thermal history of the specimens and statements made regarding the end of thermo-oxidative stability of the polymer, which is accompanied by a deterioration in the mechanical properties.In consequence of the correlation between oxidation time and antioxidant concentration the local antioxidant concentration in sheets or films can be measured by ILDTA. Thus, investigating the diffusion of an antioxidant in polypropylene using ILDTA is possible.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1988.051580119
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  • 2
    Electronic Resource
    Electronic Resource
    The interaction of Ca2+-binding proteins with the carbocyanine dye stains-allThis study was supported by NIH Grant AM 30322-04. (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 1579-1595 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The interaction of the carbocyanine dye Stains-all with the Ca2+-binding proteins calmodulin, troponin C, and parvalbumin has been monitored by means of absorption spectra and CD. In the absence of Ca2+, complexes with Stains-all of all three proteins exhibit at high dye: protein mole ratios an intense J absorption band at 600-650 nm, which is associated with a characteristic CD spectrum. In the cases of calmodulin and troponin C, the J-band is progressively lost as the dye: protein ratio decreases and is replaced by bands of the γ and β types at 450-550 nm, which likewise give rise to characteristic CD spectra. For parvalbumin, only the J-band is observed; its intensity is undiminished at the lowest dye: protein ratios examined. In the presence of excess Ca2+ the J-band is lost for all three proteins. For calmodulin and troponin C it is replaced by σ- and β-bands; in the case of parvalbumin the bound dye is released. A tentative model has been proposed to account for these observations.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360250814
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  • 3
    Electronic Resource
    Electronic Resource
    The use of nanosecond fluorometry in detecting conformational transitions of an allosteric enzyme (1975)
    New York : Wiley-Blackwell
    Biopolymers 14 (1975), S. 1933-1949 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Analysis of the time decay of fluorescence of 1-anilino-naphthalene-8-sulfonate bound to phosphorylase b reveals the presence of two components with different decay times. In glycylglycine buffer, pH 7.0, the addition of the activators AMP or IMP, or the conversion to phosphorylase a results in a preferential decrease in the amplitude of the component of longer decay time, arising probably from a preferential dissociation of 1-anilino-naphthalene-8-sulfonate from the corresponding site as a consequence of a change in molecular state.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1975.360140912
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  • 4
    Electronic Resource
    Electronic Resource
    Die vielfältigen additionsprodukte von phenylen-, naphthylen-, biphenylylen- und methylendiphenylendimethacrylaten mit radikalen aus 2,2'-azoisobutyronitrilHerrn Prof. Dr. W. Kern mit allen guten Wünschen zum 70. Geburtstag gewidmet (1976)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 177 (1976), S. 1665-1672 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: Reactions of phenylene, naphthylene, biphenylylene, and methylenediphenylene dimethacrylate (1-4) with 2,2'-azoisobutyronitrile (AIBN) were carried out without solvent, with butyllithium or sodium dihydronaphthylide in solution, and with AIBN in a great excess of refluxing benzene. Besides insoluble (crosslinked) polymers soluble polymers were obtained, among them cyclopolymers of type 9 are present as it was shown by hydrolysis, and subsequent reaction with diazomethane yielding poly(methyl methacrylate). Reactions in high dilution gave products 5 of suppressed polymerisation, of intramolecular head to tail and tail to tail addition of methacrylic acid ester groups of type 6 or 7, respectively, cyclodimers 8, and polymers 10. It was shown that the yield of the different products is influenced by the concentration of the ester, by the mole ratio of ester and AIBN, and by the distance of the phenolic oxygens in the molecule.
    Notes: Die Reaktionen von Phenylen-, Naphthylen-, Biphenylylen- und Methylendiphenylendimethacrylaten (1-4) wurden teils mit 2,2'-Azoisobutyronitril (AIBN) in Substanz oder anionisch in Lösung mit Butyllithium oder Natriumdihydronaphthylid (Naphthalinnatrium), teils mit großem Überschuß an AIBN stark verdünnt in siedendem Benzol durchgeführt. Neben unlöslichen (vernetzten) Polymeren wurden lösliche erhalten, darunter Cyclopolymere vom Typ 9, wie die Ergebnisse der Hydrolyse und anschließende Umsetzung mit Diazomethan zu Poly(methacrylsäure-methylester)n zeigten. Die Verdünnungsreaktion ergab die Produkte 5 der unterdrückten Polymerisation, der innermolekularen Addition mit Kopf/Schwanz- und Schwanz/Schwanz-Verknüpfung der Methacrylsäureestergruppen vom Typ 6 bzw. 7, Cyclodimere 8 und ebenfalls Polymere 10. Es wurde gefunden, daß der Anteil der verschiedenen Produkte von der Esterkonzentration, vom Ester/AIBN-Molverhältnis und vom Abstand der Phenolsauerstoffe in der Molekel beeinflußt wird.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1976.021770604
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  • 5
    Electronic Resource
    Electronic Resource
    Die intramolekulare, radikalische kopf-schwanzbzw. Kopf-Kopf-addition von Phenylen-, Naphthylen- und Biphenylenbis(methacrylat)enHerrn Prof. Dr. H. Mark mit allen guten Wünschen zum 80sten Geburtstag gewidmet (1975)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 1 (1975), S. 133-149 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Description / Table of Contents: 1,2-, 1,3-, and 1,4-Phenylenebis(methacrylate) (1a), (1b), and (1c), 2,3- and 1,6-naphthylenebis(methacrylate) (2a) and (2b) was as well as 2,2′-biphenylenebis(methacrylate) (3) were synthesized, using a known prescription. When these phenolic bisesters, in a highly diluted boiling benzene solution, were exposed to a large excess of 2-cyano-2-propylradicals R· (from AIBN), crystallizable compounds were formed besides a few oily viscous products. They originated from the intramolecular reaction of the two methacrylate groups and the addition of two radicals R· for each molecule. The reaction of 1c yielded only one compound which, from elemental analyses, rel. mot. mass determination, spectroscopic data, and the results of the study of the hydrolysis products, was identified to be the head to head addition product of the ester groups. Besides hydroquinone, the main hydrolysis product is a molecularly uniform tetra(methacry1ic acid) 5a with a head to head connexion between the middle units of the tetramer. The reaction of 2a as well as of 3 yielded two isomeric addition products each, the hydrolysis of which gave, in addition to the same tetra(methacry1ic acid) (5a), another isomeric tetra(methacry1ic acid) 10a with an head to tail connexion between the middle units. The mechanisms of the formation of these tetra(methacry1ic acids) 5a and 10a are discussed.
    Notes: 1,2-, 1,3- und 1,4-Phenylenbis(methacrylat) (1a), (1b) und (1c), 2,3- und 1,6-Naphthylenbis(methacrylat) (2a) und (2b) sowie 2,2′-Biphenylenbis(methacrylat) (3) wurden nach einer bekannten Vorschrift dargestellt. Setzt man stark verdünnte Lösungen dieser phenolischen Bisester in siedendem Benzol einem großen Überschuß an 2-Cyano-2-propylradikalen R. (aus AIBN) aus, so entstehen neben wenigen ölig-viskosen Produkten hauptsächlich kristallisierbare Verbindungen. Sie entstanden aus der intramolekularen Addition der zwei Methacrylatgruppen und Anlagerung von zwei Radikalen R · je Molekel. 1c gab nur eine derartige Verbindung, die nach den Elementaranlysen, der rel. mol. Masse, spektroskopischen Daten und Ergebnissen der Untersuchung der Hydrolyseprodukte aus einer Kopf/Kopf-Addition der Estergruppen hervorgegangen war. Neben Hydrochinon ist das Verseifungsprodukt eine molekulareincheitliche Tetra(methacrylsäure) 5a, in der sich die Kopf/Kopf-Verknüpfung in den mittleren Bausteinen des Tetrameren findet. Die Bisester 2a und 3 ergaben jeweils zwei isomere Additionsprodukte und bei der Hydrolyse neben der gleichen (5a) eine andere, dazu isomere Tetra (methacrylsäure) 10a, deren mittlere Bausteine Kopf/Schwanz-verbunden waren. Für die Entstehung dieser Tetra(methacrylsüren) 5a und 10a werden Mechanismen diskutiert.
    Additional Material: 5 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1975.020011975108
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  • 6
    Electronic Resource
    Electronic Resource
    Comparisons of the cure of phenol-formaldehyde novolac and resol systems by differential scanning calorimetry (1979)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 23 (1979), S. 1973-1985 
    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: Comparisons were made of differential scanning-calorimetric (DSC) thermograms of both liquid and powdered commercial phenol-formaldehyde resins. By a combination of the results from analyses under a variety of conditions, such as ambient pressure, high pressure, using freeze-dried samples, and also by direct observation of the resin-curing process in wood-veneer assemblies, the curing reactions of phenol-formaldehyde resins were found to differ for resol and novolac systems. At a heating rate of 10°C/min, the resol resin showed endothermic curing reactions at temperatures of about 150°C, while the novolac-type resin showed an exothermic peak maximum at about 160°C. Results are presented to show how DSC can be used to differentiate between a resol and novolac system.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1979.070230708
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  • 7
    Electronic Resource
    Electronic Resource
    Properties of the aminotyrosine derivatives of calmodulin (1985)
    New York : Wiley-Blackwell
    Biopolymers 24 (1985), S. 547-563 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Derivatives of calmodulin have been prepared in which tyrosine-99 and tyrosine-138 have been converted to their aminotyrosine derivatives. Significant changes in microenvironment occur in the presence of Ca2+. Both groups have a significant degree of mobility with respect to the protein matrix; this is Ca2+ dependent.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360240309
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  • 8
    Electronic Resource
    Electronic Resource
    The properties of calmodulin at physiological temperature (1986)
    New York : Wiley-Blackwell
    Biopolymers 25 (1986), S. 351-371 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Several of the physical properties of calmodulin are changed significantly upon increasing the temperature from 25 to 37°C. Among the observed changes are a minor increase in intrinsic viscosity, a decrease in molecular ellipticity in the peptide region, the development of a difference spectrum in the aromatic region, and an increase in the mobility of extrinsic fluorescent labels. Except for the latter case, the magnitudes of the changes are substantially reduced in the presence of Ca2+. The above observations are consistent with an expanded and less tightly organized structure of calmodulin at the higher temperature.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360250214
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  • 9
    Electronic Resource
    Electronic Resource
    Fluorescence dynamics studies of troponin C (1987)
    New York : Wiley-Blackwell
    Biopolymers 26 (1987), S. 1189-1204 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The time decay of fluorescence anisotropy for a dansylaziridine (DANZ) conjugate with Met-25, which lies within the N-terminal lobe of troponin C (TnC), shows at 10 and 25°C a longer correlation time characteristic of the entire molecule and a shorter correlation time arising from a more localized motion of the probe. In the absence of Ca2+, the amplitude of the shorter correlation time increases, suggesting an increased mobility of the probe. At 40°C, in both the absence and presence of Ca2+, a significant increase in probe mobility occurs. A 2,6-toluidinyl naphthalene sulfonate (2,6-TNS) complex with Ca2+-liganded TnC shows only the longer correlation time at 12 and 25°C. An N-(iodoacetylaminoethyl-5-naphthylamine-1-sulfonate) conjugate with Cys-98 shows both a long and a short correlation time; the amplitude of the shorter correlation time is greater than for the DANZ conjugate. At 9, 25, and 40°C in the presence of Ca2+, and at 9°C in its absence, the magnitude of the long correlation time is consistent with motion of the entire molecule; at higher temperatures in the absence of Ca2+ it is substantially smaller, suggesting the presence of internal rotation. For Ca2+-liganded TnC at temperatures of 25°C or lower, the results with all three labels are interpretable in terms of the crystallographic structure of TnC.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360260713
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  • 10
    Electronic Resource
    Electronic Resource
    Fluorescence anisotropy decay studies upon hemoglobin A and its subunits (1979)
    New York : Wiley-Blackwell
    Biopolymers 18 (1979), S. 1261-1276 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Fluorescent conjugates of hemoglobin A, its isolated β-chain, and the apo-derivative of the β-chain have been prepared in which the β-93 sulfhydryl was conjugated with 1,5-AEDANS. Radiationless enery transfer to the heme group results in a major decrease in fluorescence intensity and decay time. Measurements of the time decay of fluorescence anisotropy, employing single-photon counting, indicate that the apparent rotational correlation time is, in each case, substantially reduced from the value expected for a rigid molecule of the same molecular weight. This observation raises the possibility that internal degrees of rotational freedom exist.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.1979.360180516
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