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  • 1
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 1145 (1993), S. 58-62 
    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
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  • 2
    Electronic Resource
    Electronic Resource
    Springer
    European biophysics journal 23 (1995), S. 433-438 
    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
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  • 3
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 27 (1989), S. 1611-1627 
    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
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  • 4
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 32 (1994), S. 2271-2282 
    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
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  • 5
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 213-232 
    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
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  • 6
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 30 (1992), S. 489-495 
    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
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  • 7
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 28 (1990), S. 1121-1135 
    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
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  • 8
    Electronic Resource
    Electronic Resource
    Bognor Regis [u.a.] : Wiley-Blackwell
    Journal of Polymer Science Part B: Polymer Physics 29 (1991), S. 67-73 
    ISSN: 0887-6266
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Ethylene-vinyl alcohol copolymers from 0 to 57 mol % of vinyl alcohol were investigated for potential contact lens surface modification. Films of the ethylene-vinyl alcohol copolymers made by solution casting, showed that the copolymers with a high percentage of vinyl alcohol groups possessed excellent surface properties such as good wettability, low protein (albumin) and lipid adsorption, and no conformational change of the adsorbed protein. Utilizing the Langmuir-Blodgett dipping technique, an ultrathin layer of ethylene-vinyl alcohol copolymer was deposited on a silicone rubber substrate. This initial results confirm that wettability was improved and the amount of protein adsorbed was reduced significantly after only one deposition trip.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 44 (1992), S. 1331-1341 
    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: Silica is a common component in silicone elastomer formulation. Silica is known to have surface hydroxyl groups and the reactions and interactions of these surface groups with various materials have been studied extensively in the past. It is believed that the iron octoate used to combat oxidative embrittlement in silicone elastomer formulations may also react with the surface of silica, specifically fumed silica. Dynamic mechanical spectroscopy (DMS), Fourier Transform Infrared Spectroscopy (FT-IR), Electron Scanning for Chemical Analysis (ESCA), and Gel Permeation Chromatogrphy (GPC) were used to study the influence of untreated fumed silica and silica treated with dimethylsiloxane species on the iron octoate reaction. The rate of reaction was studied as a function of loading of silica. From analyzing rates of backbone scission and salt consumption, it is found that the iron octoate reacts preferentially with the surface of untreated fumed silica. Conversely, iron octoate appears to have no preferential reaction with the surface of the treated fumed silica.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 58 (1995), S. 1751-1760 
    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 potential catalysts on the curing reaction of a new type of phenolic resins obtained from benzoxazine precursors is studied. These novel resins solve the shortcomings of traditional phenolics because they cure by a ring-opening mechanism that avoids the release of volatiles. Isothermal and nonisothermal differential scanning calorimetry (DSC) data is used to determine the influence of the catalysts on the curing kinetics. Fourier transform infrared (FTIR) spectroscopy is also applied. The benzoxazine chosen for this study is a purified benzoxazine monomer based on bisphenol-A, formaldehyde, and aniline. The as-synthesized benzoxazine precursor is also studied to determine the influence of the dimers and higher oligomers in the curing mechanism. The presence of these structures seems to catalyze the curing reactions. The activation energy and overall reaction order of the as-synthesized precursor are determined. Among the catalysts tested, adipic acid shows the most promising results. For all the cases studied the curing reaction is autocatalyzed up to a diffusion-controlled stage. © 1995 John Wiley & Sons, Inc.
    Additional Material: 18 Ill.
    Type of Medium: Electronic Resource
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