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  • Polymer and Materials Science  (34)
  • Animals  (28)
  • MAN/SYSTEM TECHNOLOGY AND LIFE SUPPORT  (24)
  • Adsorption
  • 1
    Electronic Resource
    Electronic Resource
    A laser-T-jump study of the adsorption of dipolar molecules to planar lipid membranes (1988)
    Springer
    European biophysics journal 15 (1988), S. 299-310 
    Details
    ISSN: 1432-1017
    Keywords: Adsorption ; lipid membranes ; laser-T-jump ; Langmuir isotherm ; 2,4-D
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The adsorption of the herbicide 2,4-dichlorophenoxyacetic acid (2,4-D) as well as of other dipolar molecules to the interface of artificial lipid membranes gives rise to a change of the dipole potential between the membrane interior and water. As a consequence of the adsorption of the neutral species, the conductance of planar membranes, observed in the presence of the macrocyclic ion carriers nonactin or valinomycin, may change by many orders of magnitude. Using this effect in combination with a laser-T-jump technique, the kinetics of the adsorption process were measured and were interpreted on the basis of a Langmuir-isotherm. A partition coefficient (at small concentrations) of β HA =4.7·10−4 cm, a rate constant of desorption k HA≧100 s-1 and a maximum surface density N D=7.7·1013/cm2 were found. The concentration at half saturation is K HA=2.7·10-4 M. Using these values the membrane conductance induced by the ion carrier nonactin and the shape of the current-voltage relationship as a function of the ligand concentration in water was analyzed. A maxiumum dipole potential of V D max =-239 m V and a contribution of b=3.1·10-15V cm2 per single adsorbed 2,4-D molecule was found. 74% of the dipole potential acts on the inner membrane barrier separating the two interfacial adsorption planes of nonactin. The remainder (26%) favours interfacial complex formation between nonactin and K+ from the aqueous phase. The data hold for membranes formed from dioleoyllecithin in n-decane.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00256481
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  • 2
    Electronic Resource
    Electronic Resource
    A laser-T-jump study of the adsorption of dipolar molecules to planar lipid membranes (1988)
    Springer
    European biophysics journal 15 (1988), S. 321-328 
    Details
    ISSN: 1432-1017
    Keywords: Adsorption ; lipid membranes ; laser-T-jump ; Langmuir isotherm ; phloretin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract Phloretin and structurally related neutral molecules adsorb to the interface of lipid membranes and modify the electric dipole potential of the membrane/water interface. The adsorption process has been studied using a laser-T-jump relaxation technique in combination with an analysis of nonactin mediated potassium transport (see part I, Awiszus and Stark 1988). Deviations from the Langmuir isotherm were observed for most of the substance. The discrepancies were most pronounced at large surface densities, whereas good agreement was found at low concentrations in many cases. The partition coefficient in the limit of low concentrations was compared with that of octanol/water bulk phases. No correlation was found. The individual values of the two partition coefficients differed by more than three orders of magnitude. The contribution, b, of a single adsorbed molecule to the dipole potential could not be predicted from the dipole moment, μ L , of the molecule measured in the bulk phase. Different values of b were found at identical values of μ L . The study shows the limitations of the use of bulk phase data to predict molecular properties in lipid membranes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00254719
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  • 3
    Electronic Resource
    Electronic Resource
    Hydroxyl-modified epoxy resins: Some technical and analytical aspectsDedicated to Professor Dr. H. Batzer in honour of his 60th birthday (1980)
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 181 (1980), S. 1-17 
    Details
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The modification of epoxy resins by reactions involving their hydroxyl groups is described. For example, reactions with enol ethers, acrylonitrile, ethyl acetoacetate and certain other carboxylic esters, or triethyl orthoformate, gave products which had reduced reactivities towards various hardeners, and which therefore gave lower peak temperatures on cure and/or longer usable lives. Suitable modification of epoxy resins with various other reagents(certain acid anhydrides, epichlorohydrin, or N-hydroxymethylacrylamide) introduces additional useful functional groups. The uses of a diisocyanate and of α-naphthyl isocyanate to modify epoxy resins or their mixtures prior to GPC analysis are also mentioned.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/macp.1980.021810101
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  • 4
    Electronic Resource
    Electronic Resource
    Factors influencing izod impact properties of thermoplastics measured with the autographic impact test (1964)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 8 (1964), S. 119-140 
    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 standardization of notched Izod impact test data to normalized values of foot pounds per inch of notch is based on the assumption of a 1:1 increase in breaking strength with increasing notch width. This assumed relation is not supported by experimental tests on commercial thermoplastics. As notch width was increased from 1/8 to 1/4 to 3/8 to 1/2 in., nine of ten thermoplastics tested showed a decrease in normalized impact strength. Each material appears to show a characteristic loss in breaking strengths as the notch width increases. A technique developed for calibration of pendulum impact testers has been used to examine the variation of impact breaking strength in relation to the total kinetic energy of the hammer. Experimental tests show practically no change in impact strengths up to values that take 2/3 of the available hammer energy. Experimental work on the comparison of the impulse transferred by the hammer during breaking with impulse curves photographed by the Autographic Impact test show very good agreement for catastrophic breaks and fair agreement for plastic type breaks. The reduction in recorded impulse is attributed to the degrading of the sample during the plastic portion of the breaking cycle. The peak force of thermoplastics as measured by the Autographic Impact test increases as the temperature decreases from 100°C. or above to 0°C. Over the same temperature range flexural tests on small cantilever samples of these thermoplastics show the same thermal dependence for the flexural yield or permanent distortion stress. Plots of the impact peak forces and flexural yield stress at corresponding temperatures give a linear correlation. Each thermoplastic material exhibits a unique relation for this correlation between impact yielding and flexural yielding. This correlation between the impact and flexural tests over the range of temperatures is the first known experimental indication of a direct relation between impact properties and standard physical tests.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1964.070080109
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  • 5
    Electronic Resource
    Electronic Resource
    Swelling characteristics of gel fractions of formaldehyde-modified cotton cellulosesPresented in part at the Spring Meeting of The Fiber Society at Williamsburg, Va., May 1966. (1966)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 10 (1966), S. 1777-1786 
    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: A method for assessing extent of swelling of the gel fraction of formaldehyde-modified cottons, employing cupriethylenediamine hydroxide as the swelling agent, is described. Substantial differences in apparent specific volumes of swollen gel fractions are observed for cottons crosslinked by different processes to the same level of agent. The apparent crosslink density measured by the swelling of gel fraction increases with formaldehyde content of the cotton; at 0.20% formaldehyde the order of increasing crosslink density in the various processes of reaction is as follows: nonaqueous system (forms D and D′) 〈 aqueous system (forms W and W′) 〈swelling system (form F) 〈 vapor system (form V) 〈 bake-cure system (form C).
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1966.070101115
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  • 6
    Electronic Resource
    Electronic Resource
    Direct observation of cell wall glucans in whole cells of Saccharomyces cerevisiae by magic-angle spinning 13C-nmr (1994)
    New York : Wiley-Blackwell
    Biopolymers 34 (1994), S. 1627-1635 
    Details
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: Intact cells of Saccharomyces cerevisiae were examined as an aqueous paste by 13C-nmr spectroscopy with direct polarization and magic-angle spinning. The spectra obtained were highly resolved, showing numerous resonances in the 60-105 ppm range that were assigned to carbons of a liquid-like domain of the cell wall glucan. Assignments were confirmed by running the spectrum of S. cerevisiae in which the cell wall glucans were labeled with [13C] by feeding the cell [13C ] galactose. The spectra indicate that the glucan in the cell wall of intact S. cerevisiae assumes a helical conformation and suggest that strain 17A fed with galactose preferentially incorporates the resulting glucose into β(1 → 3)-linkages. © 1994 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/bip.360341207
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  • 7
    Electronic Resource
    Electronic Resource
    Analysis of resorcinol-phenol-formaldehyde resins by NMR spectroscopy (1972)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 26 (1972), S. 171-176 
    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: Es wird eine NMR-Methode zur Bestimmung der ungefähren Verhältnisse zwischen aus Phenolkernen, Resorcinkernen und Formaldehyd gebildeten Gruppenin Kondensationsprodukten aus Phenol, Resorcin und Formaldehyd beschrieben.
    Notes: A method is reported, based on NMR spectroscopy, for approximate determination of the component ratios of resins formed by condensation of resorcinol, phenol and formaldehyde.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1972.050260113
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  • 8
    Electronic Resource
    Electronic Resource
    Organo-metal carbonyl compounds of iron, molybdenum, and manganese as photosensitisers of the anhydride cure of epoxy resins (1976)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 50 (1976), S. 9-14 
    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: Verbindungen der Strukturformeln [π-C5H5M(CO)nX] (M = Fe, n = 2; M = Mo, n = 3; X = CH3, CH2C6H5, CH2Si(CH3)3, CH2OCH3, Sn(C6H5)3, SnCl3, HgCl, I), [Mn(CO)5CH3], und [(π-CH3C5H4)Mn(CO)3] wurden als Katalysatoren für die Härtung von Epoxidharzen unter verschiedenen Bedingungen geprüft. Es wurde gefunden, daß die Verbindungen [π-C5H5Fe(CO)2R] (R = CH3, CH2C6H5) und [π-C5H5Mo(CO)3CH3] wirksame lichtempfindliche Beschleuniger für die Anhydridhärtung von Expoxidharzen sind. Der Aktivierungsmechanismus wird diskutiert.
    Notes: Compounds of the types [π-C5H5M(CO)nX] (M = Fe, n = 2; M = Mo, n = 3; X = CH3, CH2C6H5, CH2Si(CH3)3, CH2OCH3, Sn(C6H5)3, SnCl3, HgCl, I), [Mn(CO)5CH3], and [(π-CH3C5H4)Mn(CO)3] have been examined as catalysts for the cure of epoxy resins under various conditions. It was found that the compounds [π-C5H5Fe(CO)2R] (R = CH3, CH2C6H5) and [π-C5H5Mo(CO)3CH3] are active photosensitizing agents for the anhydride cure of certain epoxy resins. The mechanism of the process is discussed.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1976.050500102
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  • 9
    Electronic Resource
    Electronic Resource
    Paramagnetic shifts induced by europium and praseodymium chelates in the NMR spectrum of bisphenol a diglycidyl ether (1972)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 27 (1972), S. 159-164 
    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: Es wurde eine Voruntersuchung des Einflusses unternommen, den die Verschiebereagenzien Tris-(dipivaloylmethano)-europium uncl Tris-(dipivaloylmethano)-pra-seodym auf das NMR-Spektrum des Diglyzidyläthers des Bisphenol A ausüben. Es ergab sich, daß die Signale der am Epoxidring anliegenden Protonen durch den Zusatz dieser Chelate weit mehr als die Signale der exozyklischen -OCH2-Gruppen verschoben werden. Die Verschiebung kann man durch den Zusatz eines Alkohols rückgängig machen, der vorzugsweise mit dem Verschiebemittel reagiert.
    Notes: A preliminary study has been made of the effects of the shift reagents Eu (DPM)3 and Pr(DPM)3 on the NMR spectrum of Bisphenol A diglycidyl ether (I). Protons attached to the epoxy ring were observed to shift appreciably more than protons of the exocyclic —OCH2— group, on addition of these chelates. The shifts could be reversed by addition of an alcohol, which interacted preferentially with the shift reagent.
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1972.050270111
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  • 10
    Electronic Resource
    Electronic Resource
    Paramagnetic shifts induced by europium and praseodymium complexes in the NMR spectra of some substituted phenols (1972)
    Weinheim : Wiley-Blackwell
    Angewandte Makromolekulare Chemie 27 (1972), S. 151-157 
    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: Es wurden die Verschiebungen untersucht, die durch Tris-(dipivaloylmethano)-europium und Tris-(dipivaloylmethano)-praseodym im NMR- Spektrum versehiedener Derivate substituierter Phenole hervorgerufen werden. Der Zweck dieser Arbeiten war, die Möglichkeiten zu erfassen, die diese Verschiebereagenzien als Hilfsmittel in der NMR-Analyse von Phenolharzen bieten, und Information über Verschiebungen bei Molekülen zu gewinnen, die mehr als eine Koordinationsposition besitzen.
    Notes: An investigation into the shifts induced in the NMR spectra of some derivatives of substituted phenols by tris(dipivalomethanato)europium and tris(dipivalomethanato)praseodymium is reported. The phenol derivatives were studied to ascertain the possible utility of the shift reagents as an aid in the analysis of phenolformaldehyde resins by NMR spectroscopy, and to gain information on induced shifts with molecules having more than one possible co-ordination site.
    Additional Material: 1 Tab.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/apmc.1972.050270110
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