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  • Electronic Resource  (6)
  • Polymer and Materials Science  (5)
  • Arctic Amerasian shelf Sediment carbon and nitrogen isotopes  (1)
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  • Electronic Resource  (6)
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  • 1
    Electronic Resource
    Electronic Resource
    Organic carbon isotope ratios (δ13C) of Arctic Amerasian Continental shelf sediments (2000)
    Springer
    International journal of earth sciences 89 (2000), S. 522-532 
    Details
    ISSN: 1437-3262
    Keywords: Arctic Amerasian shelf Sediment carbon and nitrogen isotopes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Geosciences
    Notes: Abstract. Organic matter origins are inferred from carbon isotope ratios (δ13C) in recent continental shelf sediments and major rivers from 465 locations from the north Bering-Chukchi-East Siberian-Beaufort Sea, Arctic Amerasia. Generally, there is a cross-shelf increase in δ13C, which is due to progressive increased contribution seaward of marine-derived organic carbon to surface sediments. This conclusion is supported by the correlations between sediment δ13C, OC/N, and δ15N. The sources of total organic carbon (TOC) to the Amerasian margin sediments are primarily from marine water-column phytoplankton and terrigenous C3 plants constituted of tundra taiga and angiosperms. In contrast to more temperate regions, the source of TOC from terrigenous C4 and CAM plants to the study area is probably insignificant because these plants do not exist in the northern high latitudes. The input of carbon to the northern Alaskan shelf sediments from nearshore kelp community (Laminaria solidungula) is generally insignificant as indicated by the absence of high sediment δ13C values (–16.5 to –13.6‰) which are typical of the macrophytes. Our study suggests that the isotopic composition of sediment TOC has potential application in reconstructing temporal changes in delivery and accumulation of organic matter resulting from glacial–interglacial changes in sea level and environments. Furthermore, recycling and advection of the extensive deposits of terrestrially derived organic matter from land, or the wide Amerasian margin, could be a mechanism for elevating total CO2 and pCO2 in the Arctic Basin halocline.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s005310000121
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  • 2
    Electronic Resource
    Electronic Resource
    Thermally stable high molecular weight polyoxymethylenes (1959)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 1 (1959), S. 158-163 
    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: In this, the first of a series of five papers, the historical development of formaldehyde polymers, beginning with the work of Butlerov and continuing through the investigations of Staudinger and his collaborators, is reviewed. Recent studies in these laboratories have led to thermally stable high polymers of formaldehyde. Initiators and the role of impurities in the polymerization are described. An explanation is offered to account for differences in thermal stabilities between old and new polymers. Esterification, by which further increases in thermal stability are achieved, is described. It is proposed that the generic term “acetal resin” be used to described high polymers that are composed of repeating oxymethylene units.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1959.070010205
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  • 3
    Electronic Resource
    Electronic Resource
    Permeation of gases through modified polymer films. V. Permeation and diffusion of helium, nitrogen, methane, ethane, and propane through γ-ray crosslinked polyethyleneCorrected proofs received April 27, 1981 (1981)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 26 (1981), S. 2239-2263 
    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 permeation and diffusion of helium, nitrogen, methane, ethane, and propane through γ-irradiated polyethylene films were investigated. These studies were carried out with two objectives in mind: (1) to determine the effect of crosslinking by γ irradiation on permeability and diffusivity using the gas molecules as molecular probes; and (2) to study the plasticizing effects of the low hydrocarbons on the polyethylene film. The γ-ray-induced crosslinking efficiency of polyethylene was investigated in the following irradiation atmospheres: vacuum, acetylene, and nitrogen-acetylene mixtures. Results showed that irradiation in acetylene decreased the crosslinking efficiency while an acetylene-nitrogen atmosphere increased the efficiency compared to irradiation in vacuum. Both the permeation constants and the diffusion coefficients were found to decrease with increasing irradiation dose while the activation energies increased. The permeation constants of the organic gases through polyethylene increased with molecular diameter while the diffusion coefficients decreased. This increase in permeability was attributed to an increase in the solubility due to solubilization of the membrane by the penetrant. For example, the molecular diameter of propane is 4.397 Å compared with 2.807 Å for methane; however, propane permeated the polyethylene film at a rate twice that of methane. Nitrogen and methane have approximately the same molecular diameters - 2.7085 and 2.807 Å, respectively - but owing to the plasticizing effect of methane, it permeated the film at a rate three times greater than that of nitrogen. It is interesting to note that the stronger the plasticizing ability of the penetrant, the greater the effect of the irradiation dose. The permeability of propane decreased by 40.7%, while the permeability of helium decreased by 6.4% after an irradiation dose of 50 Mrad.
    Additional Material: 22 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1981.070260713
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  • 4
    Electronic Resource
    Electronic Resource
    Studies of surface composition, structure and oxygen adsorption of Ni3Al(110) by Li+ and He+ ion scattering (1992)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 18 (1992), S. 729-739 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The surface composition, structure and initial stages of oxygen adsorption of Ni3Al(110) have been investigated by ISS. The surface composition of the Ni3Al(110) surface was determined by Li+ and He+ ion scattering using selected scattering geometries. These results consistently show a surface composition of 50% Ni-50% Al in the outermost layer with some small percentage of Ni enhancement (perhaps 1-2%), while the second layer is basically Ni. The surface structure has been probed by measuring the intensity of Li+ ion scattering as a function of incident angle along the [001], [112], [111], [332] and [110] azimuthal directions. The interpretation of experimental data is based on the calibrated shadow cone and chain model simulations. The results show that there is no displacement of first-layer Al relative to first-layer Ni, but there is a contraction in the first-to-second layer spacing of 0.11 ± 0.08 Å. The adsorption of oxygen at low exposure (∼8L) and pressures in the range 2 × 10-8-1 × 10-6 mbar at a temperature of 700°C shows the disappearance of the Ni ISS signal, and the results suggest the formation of a monolayer of an AlOx overlayer. Using a model similar to that previously studied for the formation of AlOx islands on the Ni3Al(001) surface, this oxide overlayer has been shown to be AlOx islands with no influence on remaining areas on the crystal. The mechanism for apparent interchange of the Al atoms to the surface to replace the Ni atoms is also discussed.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740181007
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  • 5
    Electronic Resource
    Electronic Resource
    Oxygen adsorption on Ni3Al(001) by low-energy ion beams (1991)
    Chichester [u.a.] : Wiley-Blackwell
    Surface and Interface Analysis 17 (1991), S. 903-910 
    Details
    ISSN: 0142-2421
    Keywords: Chemistry ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Physics
    Notes: The interaction of O with the Ni3Al(001) surface has been studied using low-energy He+ scattering. Oxygen adsorption at an exposure of 10 L and a temperature of 700°C results in the total disappearance of the Ni ISS signal, indicating the formation of a monolayer AlOx overlayer. This oxide AlOx overlayer has been examined by measuring the azimuthal angle dependence of the scattered ion yield at fixed scattering angle under different coverages of oxygen. The azimuthal variations of the Ni and Al ISS signals from the O-covered surface are compared with those of Ni and Al from the clean surface, and the results used to derive a value for the fractional coverage of oxygen on the surface. The analysis supports the model that the oxide initially grows in the form of islands, with no influence on remaining areas of the crystal. No evidence of the ordering of the oxide islands was observed. Further evidence of the growth of the AlOx surface. The results indicate that the remaining (uncovered) Ni3Al surface retains the crystal structure of a clean surface. The rate of growth of the AlOx islands on the Ni/3Al(001) surface was also found to be related to temperature.
    Additional Material: 10 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/sia.740171303
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  • 6
    Electronic Resource
    Electronic Resource
    Methylene malonamide. I. Synthesis and reactivity of the monomer (1982)
    New York : Wiley-Blackwell
    Journal of Polymer Science: Polymer Chemistry Edition 20 (1982), S. 35-42 
    Details
    ISSN: 0360-6376
    Keywords: Physics ; Polymer and Materials Science
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The first confirmed synthesis of methylene malonamide (MeMal) is reported. This monomer was prepared by the thermal elimination or fluoride-ion-initiated elimination of trimethylsilyl chloride from α-chloro-α(trimethylsilyl-2-methyl) malonamide. Spectral data for the monomer are given. MeMal has been shown to be unstable in a variety of protic organic solvents, including water and alcohols, thus giving the appropriate (α-methyl) substituted malonamides. MeMal is stable in most aprotic solvents.
    Additional Material: 5 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/pol.1982.170200104
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