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  • 1
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 25 (1997), S. 202-208 
    ISSN: 0142-2421
    Keywords: diffraction ; elliptical mirror ; energy distribution ; Fermi edge ; monochromator ; optical ray tracing ; rocking curve ; scanning x-ray probe ; simulation ; XPS ; Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The energy distribution of a scanning x-ray probe which is equipped with an elliptical mirror monochromator has been simulated with optical ray tracing, a numerically described energy distribution of Al Kα x-ray and a rocking curve. The rocking curve was estimated by dynamic diffraction theory with structure factors for quartz. The peak energy of the diffracted x-ray beam did not change with beam size, although the shapes of energy distribution were found to change slightly. Using the simulated x-ray energy distribution and the apparatus function, the energy width of the Fermi edge was simulated, which is to be compared with that obtained experimentally by monochromatic Al Kα x-ray excitation. The widths of the silver Fermi edge spectra were measured with different x-ray beam sizes. In addition, the relation between the x-ray beam position on the anode and the diffracted x-ray energy distribution was investigated. The peak energy of the diffracted x-ray beam was found to move with the x-ray beam position. It is shown that this kind of simulation can be effectively used for estimating the energy distribution and the intensity distribution of the diffracted x-ray beam. © 1997 by John Wiley & Sons, Ltd.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 2
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 14 (1989), S. 46-52 
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: Coatings are applied to particulate materials to enhance surface properties while retaining desired bulk properties. Characterization of such coatings presents a challenge. In this paper we present an example of a particle surface analysis and assess how factors such as roughness and coating thickness distributions affect quantitative conclusions. Silica coatings were deposited from aqueous solution on to α-alumina particles of 150 nm average size. Transmission electron microscopy, x-ray photoemission spectroscopy and secondary ion mass spectrometry/depth profiling were used to analyze coatings of thicknesses of tens of nanometers to submonolayer. The three techniques were in excellent agreement in the thickness ranges where they overlapped. XPS does not allow assessment of the uniformity or thickness distribution of the coatings. However, depth profiles are quantitatively consistent with a model of random attachment of the silica units to the particle surface during growth, with no preference for the uncoated alumina surface over the previously deposited silica.
    Additional Material: 8 Ill.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 25 (1980), S. 2975-2984 
    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 two-parameter equation is developed that allows for the estimation of the enthalpies of hydrogen formation between two compounds. The compound acting as a proton donor is assigned a donating parameter, and the compound acting as a proton acceptor is assigned an accepting parameter. The compounds described can be assigned both a donating and an accepting parameter. These parameters are derived either from the observed linear relationship between measured hydrogen bond enthalpies and the shift in the OH stretching frequency of alcohols or from the estimated contribution of hydrogen bonding to the cohesive energy density of liquids. The donating parameters correlate well with observed autoprotolysis constants for the several compounds, and the accepting parameters correlate well with observed equilibrium constants for the protonation reaction in which a compound (base) gains a proton. The ability to estimate enthalpies is important in predicting polymeric resin solubilities in solvents.
    Additional Material: 9 Tab.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 31 (1986), S. 965-977 
    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: Liquid crystal polymers (LCP) have been developed for the first time as a thermoplastic matrix for high-performance composites. A successful melt impregnation method has been developed that results in the production of continuous carbon fiber (CF)-reinforced LCP prepreg tape. Subsequent layup and molding of prepreg into laminates has yielded composites of good quality.Tensile and flexural properties of LCP-CF composites are comparable to those of epoxy-CF composites. LCP-CF composites have better impact resistance than the latter, although epoxy-CF composites possess superior compression and shear strength. LCP-CF composites have good property retention until 200°F (67% of room temperature value). Above 200°F, mechanical properties are found to decrease significantly. Experimental results indicate that the poor compression and shear strength may be due to the poor interfacial adhesion between the matrix and carbon fiber.
    Additional Material: 11 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 32 (1986), S. 5245-5245 
    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
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Die Makromolekulare Chemie 15 (1989), S. 31-37 
    ISSN: 0025-116X
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Some results are reported on the alkyllithium-initiated polymerization of butadiene in cyclopentane in presence of 2,′2-bis(4,4,6-trimethyl-1,3-dioxane). The effect of this lithium chelating agent on one-unit model active centres is also reported. Comparisons are made with another highly efficient polymer structure modifier, 1,2-dipiperidinoethane. Conclusions are reached on the reasons why both are particularly effective in inducing the formation of polydienes having extremely high vinyl content.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Physics Edition 23 (1985), S. 2203-2216 
    ISSN: 0098-1273
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Spectroscopic studies have been performed on aqueous dispersions of the surfactant 1,2-bis(10,12-tricosadiynoyl)-sn-glycero-3-phosphocholine before and after polymerization with ul-traviolet light. Monomers of this lipid can, under certain conditions, convert from the expected spherical liposomal form to a unique phase consisting of hollow tubules. To determine the molecular conformation of these structures we have used Raman and infrared spectroscopies to probe the structure of the hydrocarbon chains and head groups of the lipids, and used absorption spectroscopy and resonance enhanced Raman scattering of the colored polymer to monitor the length and structure of the diacetylenic polymer backbone. Unusual C—H stretch-ing Raman bands imply that the hydrocarbon chain packing in the monomeric bilayers is different from that observed in other phosphatidylcholines, and that a distrubance in alkyl chain packing occurs on polymerization. Depending on irradiation conditions and the dispersal state of the lipid the polymer chains may be of at least three different colors, from which distinct resonance Raman spectra are obtained. The effective bond conjugation lengths range from quite short in the yellow polymer produced in sonicated vesicles to extremely long in a blue component seen in polymerized tubules.
    Additional Material: 9 Ill.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 0022-3832
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: The presence of a p-bromoaniline initiator fragment in polyglycine formed from N-carboxyglycine anhydride has been confirmed by bromine and infrared analyses. Carius halogen analyses, sodium fusions, and Beilstein halogen tests prove the presence of bromine in the polymer. Both the per cent bromine and the per cent amino nitrogen data specify essentially the same molecular weight, 1500-1700, for the polymer. Per cent yield of polymer data provide a second-order catalytic constant for p-bromoaniline-initiated polyglycine in dioxane at 37°C. of 1.8 × 10-3 l. mole-1 sec.-1 for the first 51% of the reaction, and the calculated constant beyond that falls off rather rapidly.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 9
    ISSN: 0935-9648
    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
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    New York : Wiley-Blackwell
    Biopolymers 32 (1992), S. 1623-1629 
    ISSN: 0006-3525
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The potentials of mean force (pmfs) for rotation around the X1 aromatic side-chain dihedrals of the zwitterionic bis-penicillamine enkephalin pentapeptide have been determined in both aqueous and saline solution. These side chains are known to be associated with the pharmacophore and their conformational populations are thought to be critical for activity. It is found that the association between chloride ions and the peptide in saline solution simulations has profound effects on the relative energies of the g-, g+, and t conformations, and also the barriers between them. Using the pmfs we have also calculated the respective Boltzmann-weighted 3Jαβ vicinal coupling constants. The agreement between the calculated and experimentally determined coupling constants is poor for the pmf in pure water, but substantially improved for the pmf determined in saline solution. Reasons for these differences appear to be related to the experimental conditions. © 1992 John Wiley & Sons, Inc.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
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