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  • 1
    Electronic Resource
    Electronic Resource
    Effect of sub-skinning concentrations of saponin on intracellular Ca^2^+ and plasma membrane fluidity in cultured cardiac cells
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 1145 (1993), S. 58-62 
    Details
    ISSN: 0005-2736
    Keywords: Calcium ion, intracellular ; FRAP ; Intracellular calcium ion ; Membrane fluidity ; Saponin
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0005-2736(93)90381-9
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  • 2
    Electronic Resource
    Electronic Resource
    Age-dependent changes in the phosphorylation of nuclear proteins of submandibular glands in isoproterenol-treated rats
    Amsterdam : Elsevier
    Mechanisms of Ageing and Development 70 (1993), S. 127-137 
    Details
    ISSN: 0047-6374
    Keywords: Aging ; Histone proteins ; Isoproterenol ; Non-histone proteins ; Phosphorylation ; Submandibular gland
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0047-6374(93)90064-X
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  • 3
    Electronic Resource
    Electronic Resource
    Rapid accumulation of fluorescent material with aging in an oxygen-sensitive mutant mev-1 of Caenorhabditis elegans
    Amsterdam : Elsevier
    Mechanisms of Ageing and Development 74 (1994), S. 161-170 
    Details
    ISSN: 0047-6374
    Keywords: Aging ; Caenorhabditis elegans ; Fluorescent material ; Oxygen-sensitive mutant
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Medicine
    Type of Medium: Electronic Resource
    URL: http://linkinghub.elsevier.com/retrieve/pii/0047-6374(94)90087-6
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  • 4
    Electronic Resource
    Electronic Resource
    Density-associated changes in platelet-activating factor acetylhydrolase activity and membrane fluidity of human erythrocytes (1994)
    Springer
    Annals of hematology 69 (1994), S. 139-145 
    Details
    ISSN: 1432-0584
    Keywords: Aging ; Erythrocytes ; Platelet-activating factor ; Acyltransferases ; Membrane fluidity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Summary Platelet-activating factor acetylhydrolase is known to degrade oxidatively fragmented phospholipids which are similar in structure to platelet-activating factor. We examined changes of acetylhydrolase activity during in vivo aging of human erythrocytes and tried to assess its role in maintaining the membrane properties of erythrocytes. Higher-density erythrocytes are enriched with older cells. Erythrocytes obtained from seven healthy colleagues were separated into four density fractions by centrifugation in discontinuous Percoll density gradients. Both membrane and cytosolic acetylhydrolase decreased with increasing erythrocyte density. Membrane and cytosolic acetylhydrolase activities in the lightest fraction were 2.0±1.0 (SD) nkat/g protein and 362±58 pkat/g protein, respectivley, and these values were significantly higher than those in the densest fraction: 1.3±0.7 nkat/g protein and 286±70 pkat/g protein, respectively. Membrane acyltransferase activity also decreased with red cell density and the average values in the lightest and densest fractions were 51.2±23.6 and 27.0±20.2 μkat/g protein, respectively. Generation of thiobarbituric acid-reactive substances induced byt-butyl hydroperoxide treatment decreased with increasing cell density, and the inhibition of acetylhydrolase with diisopropylfluorophosphate resulted in enhanced peroxide-induced lipid oxidation, particularly in lower-density fractions. There was no significant change in basal levels of thiobarbituric acid-reactive substances in red cell membrane. Membrane fluidity was evaluated by fluorescence recovery after photobleaching and it decreased as erythrocyte density increased. We conclude that the activity of the deacylation/reacylation cycle maintained by acetylhydrolase and acyltransferase is gradually reduced during in vivo aging of erythrocytes. This may be connected with decreases of polyunsaturated fatty acids and membrane fluidity in old eryhtrocytes.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01695695
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  • 5
    Electronic Resource
    Electronic Resource
    Lateral mobility of phospholipid molecules in thin liquid films (1995)
    Springer
    European biophysics journal 23 (1995), S. 433-438 
    Details
    ISSN: 1432-1017
    Keywords: Lecithin ; Foam films ; Lateral diffusion ; FRAP ; PEG
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Physics
    Notes: Abstract The Fluorescence Recovery After Photobleaching (FRAP) method was applied to measure the lateral mobility of the fluorescent lipid analog, dioctadecylindocarbocyanine perchlorate (Dil-C18), in microscopic thin liquid films (Foam Films (FFs)). The foam film structures were comprised of two phosphatidylcholine monolayers adsorbed at air/water interfaces which sandwiched a thin liquid core. Lateral diffusion of the DiI molecules in the plane of the monolayers was determined as a function of the thickness of the thin liquid core of the film between the FF monolayers. The results obtained indicated that the diffusion coefficient was strongly dependent both on the distance between the FF monolayers in the range 4 nm to 85 nm (corresponding to the FF thickness) and on the film type. The applicability of the FRAP method for studying the molecular mobility in phospholipid FFs was demonstrated. Considerable differences in the surface diffusion coefficient of Dil were observed, ranging between 2 × 10−8 cm2/s and 22 × 10−8 cm2/s in so called yellow, gray, common black and Newton black FFs. The effect of the presence of polyethylene glycol (PEG-400) in the liquid core of lecithin FFs on surface diffusion was also studied. The surface diffusion results from the FF studies were compared with data from black lipid membranes (BLMs). These structures are related in thickness terms but the molecular orientation in FFs is the reverse of that in BLMs.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00196830
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  • 6
    Electronic Resource
    Electronic Resource
    Polymerization of diethynyldiphenylmethane: DSC, FTIR, NMR, and dielectric characterization (1989)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 1611-1627 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: 4,4′-Diethynyldiphenylmethane thermally polymerizes by a free radical mechanism to a highly crosslinked structure of interest as a high temperature composite matrix resin. The polymerization reaction was characterized by differential scanning calorimetry, Fourier-transform infrared (FTIR) spectroscopy, 1H and 13C nuclear magnetic resonance (NMR) spectroscopy, and microdi-electrometry. The predominant reaction mechanism appears to be linear polymerization through the acetylene end groups, which follows first-order kinetics. However, during the early stages of reaction a second, more rapid polymerization mechanism is evident; it is postulated that this is the formation of a cyclic trimer, which is kinetically favored but sterically prohibited as the crosslinked network grows. Formation of a liquid crystalline trimer is hyppthesized; such intermediate formation is supported by intensity increases in the aromatic region of the NMR spectra, by FTIR difference spectroscopy comparisons with model compounds, and by enhancement of conductivity as observed by microdielectrometry.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1989.090270803
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  • 7
    Electronic Resource
    Electronic Resource
    Molecular level study of the crystallization of a thermoplastic polyimide by infrared spectroscopy (1994)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2271-2282 
    Details
    ISSN: 0887-6266
    Keywords: Polyimide, thermoplastic, semicrystalline ; Fourier transform infrared spectroscopy (FTIR) ; crystallization process ; intramolecular rotation ; intermolecular chain packing ; local molecular order ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The crystallization process of the thermoplastic polyimide derived from 3,3′,4,4′-benzophenonetetracarboxylic dianhydride (BTDA) and 2,2-dimethyl-1,3,-(4-aminophenoxy) propane (DMDA) is studied at the molecular level by utilizing infrared spectroscopy's sensitivity to local molecular environment. Assignments of the unique spectral features appearing upon crystallization are made with additional verification from crystalline model imide compounds. A direct comparison of an annealed polyimide film studied by both infrared spectroscopy and x-ray diffraction shows fairly close agreement in the amount of crystallinity obtained. The unique crystalline infrared spectral features provide insight into the molecular mechanism involved with the crystallization process. Spectral shifts occurring upon crystallization reflect intramolecular rotations toward increased coplanarity as well as intermolecular chain packing of certain molecular groups at specific sites of the chain backbone. The site specific information is then used to study the relative kinetic behavior of the intramolecular and intermolecular effects occurring during crystallization. © 1994 John Wiley & Sons, Inc.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1994.090321314
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  • 8
    Electronic Resource
    Electronic Resource
    Surface modification of contact-lens materials by silanization: An FTIR-ATR study (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 213-232 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The adsorption, desorption, and orientation characteristics of two long-chain chlorosilane compounds, octadecyltrichlorosilane and 1-undecylene-dimethylchlorosilane, onto poly(methyl methacrylate) (PMMA) and poly(2-hydroxyl-ethyl methacrylate) (PHEMA) are studied using Fourier-transform infrared attenuated total reflection (FTIR-ATR) spectroscopy. Quantitative monitoring of the amount of silane adsorbed is also attempted. It is believed that the surface modification reaction has been successfully confined to monolayer coverages and that sufficient detection sensitivity has been achieved to observe the reaction at these low levels on both PMMA and PHEMA. Also, ATR polarization studies indicate that on both substrates, a definite preference for orientation exists such that the long molecular axis is perpendicular to the substrate surface. The silanes are observed to be only physisorbed onto the PMMA surface under the anhydrous conditions applied during adsorption, whereas a chemical reaction is observed on the PHEMA surface.
    Additional Material: 16 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090280208
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  • 9
    Electronic Resource
    Electronic Resource
    FTIR separation of nylon-6 chain conformations: Clarification of the mesomorphous and γ-crystalline phases (1992)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 489-495 
    Details
    ISSN: 0887-6266
    Keywords: infrared spectra of Nylon-6 chain conformation ; Nylon-6 chain conformation, FT-IR separation of ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Specific infrared absorptions for each form of Nylon-6 have been indentified. Quenched films were prepared by melt casting and converted in turn to the α-crystalline and γ-crystalline structures. The films were examined using Fourier transform infrared spectroscopy (FTIR) with the attenuated total reflection configuration and by X-ray diffractometry. The FTIR spectrum of the pure mesomorphous component of the quenched film was calculated by subtracting away the contribution of α-crystalline peaks present due to incomplete quenching. A curve-fitting procedure was applied to the pure mesomorphous and gamma crystalline spectra. Several peaks in the mesomorphous spectrum are observed to develop a shoulder upon conversion to the γ-crystalline form. This is due to the extra gauche character imparted to the C—N bond between the methylene unit and the amide group. These and other band assignments were confirmed by analysis of model compounds.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1992.090300508
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  • 10
    Electronic Resource
    Electronic Resource
    Influence of the surface treatment of graphitized carbon fibers on the curing of an amine-catalyzed epoxy-anhydride system (1990)
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1121-1135 
    Details
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The surface of graphitized carbon fibers is oxidatively treated by nitric acid. Fourier transform infrared attenuated total reflection spectroscopy has been utilized to monitor the influence of the surface species on the curing of an epoxy system. A curve-fitting program is used to deconvolve the overlapped infrared bands. The integrated intensities of the ester, anhydride, epoxy, and carboxylic acid, plotted against the curing time, clearly show the dependence of the crosslinking process on the concentration of the surface species. The surface groups themselves act as a catalyst: there exists an optimal concentration below which an activation of the curing process occurs. Above that concentration, a retardation of the curing process has been detected.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/polb.1990.090280710
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