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  • 1
    Electronic Resource
    Electronic Resource
    NMR studies of plasticizer motions in a polymer matrix (1992)
    s.l. : American Chemical Society
    Macromolecules 25 (1992), S. 3365-3368 
    Details
    ISSN: 1520-5835
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/ma00039a008
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  • 2
    Electronic Resource
    Electronic Resource
    Trophic ecology of Rimicaris exoculata : a combined lipid abundance/stable isotope approach (1999)
    Springer
    Marine biology 133 (1999), S. 495-499 
    Details
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The alvinocaridid shrimp Rimicaris exoculata is an abundant component of the biota of Mid-Atlantic Ridge hydrothermal vents. To determine the nutritional strategy of this organism, we analysed the molecular abundance and carbon isotopic composition of its phospholipid fatty acids. High abundances of n-7 fatty acids (〉40% total fatty acids) were observed in R. exoculata muscle tissues, in bacterial epibionts scraped from its gill bailers, and from the bacterially infested metal sulphides that the shrimp ingest. The phospholipid fatty acid abundance data indicates that the bacteria in the sulphides are closely related to the bacterial epibiota inhabiting the shrimp gill bailers, carapace and other body parts. Compound specific δ13C analyses of the phospholipid fatty acids gave average values of −12‰ for the epibiont bacteria and −21‰ for the sulphide bacteria. This difference may be largely due to the expression of different forms of RuBisCO (Forms I and II) which fractionate against 13C to different extents. Carbon limitation within the shrimp epibiont population may be an additional factor. The δ13C values (mean = −13‰) of the saturated and monounsaturated fatty acids isolated from the muscle tissues of R. exoculata were very close to those of the epibionts, indicating that the predominant source of dietary carbon for the shrimp is their epibionts, with a lesser contribution from free-living bacteria. The δ13C values (−26‰) of shrimp cholesterol were much more negative than those of the fatty acids, and this cholesterol is likely to have derived from the oceanic photic zone.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/s002270050489
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  • 3
    Electronic Resource
    Electronic Resource
    Studies of polymer morphology with 13C inversion recovery cross polarization NMR (1989)
    Springer
    Polymer bulletin 21 (1989), S. 229-234 
    Details
    ISSN: 1436-2449
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics , Physics
    Notes: Summary Inversion recovery cross polarization (IRCP) NMR was used to study the solid state morphologies of plasticized and neat poly(vinyl butyral-co-vinyl alcohol) (PVB), of polyether polyurethane elastomers (PU), and of low density polyethylene (LDPE). IRCP decay data for these polymers were best fit to a biexponential two-component model modulated by T1ϱH relaxation. These results clearly display the two-phase nature of these polymers, as well as the potential applicability of the IRCP technique.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00266178
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  • 4
    Electronic Resource
    Electronic Resource
    The functional significance of the microbial biomass in organic and conventionally managed soils (1995)
    Springer
    Plant and soil 170 (1995), S. 87-97 
    Details
    ISSN: 1573-5036
    Keywords: biomass ; FAME ; fatty acid methyl esters ; microbial community structure ; microbial ecology ; organic and conventional management ; phospholipid fatty acids ; PLFA ; soil processes
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract In order to achieve sustainability in managed ecosystems we must understand management impacts on soil processes and clarify the regulatory role of the microbial community on these processes. Crop rotation and organic management practices are thought to have positive impacts on the microbial biomass; however, the specific impacts of crop rotation organic management on soil microbial ecology are largely unknown. The effect of organic management on soil microbial ecology was investigated using soils collected from the Rodale Institute Research Center's long-term Farming Systems Trial (FST) experiment. The FST, begun in 1981, included a manured and a cover cropped organic rotation and a conventionally managed grain based rotation. Soil respiration rates and13C-isotope fate in a companion study suggest that the biomass characteristics of the FST treatment soils were different in November 1991. However, direct measurement of the microbial community at this time using Phospholipid Fatty Acid Analysis (PLFA) did not identify statistically significant treatment based differences in soil biomass characteristics. Variability among the PLFA profiles of treatment replicates was as great as variability between farming systems. Treatment based trends were observed among selected PLFAs, particularly those present in large amounts, that were consistent with indirect biomass and biomass-dependent measures. Overall, PLFA profiles, soil respiration rates and13C-cycling suggested that the organic cover cropped soil had the Largest and most heterogeneous microbial population while the biomass of the organic-manure amended soil was the least heterogeneous, and the most metabolically active.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF02183057
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  • 5
    Electronic Resource
    Electronic Resource
    A preliminary correlation between macroscopic and microscopic polymer properties: Dynamic storage modulus vs. CPMAS NMR cross polarization rates (1990)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 40 (1990), S. 1717-1725 
    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 correlation has been established between the dynamic storage modulus (E') and the mean cross polarization time constants 〈TCH〉 for a set of five morphologically diverse polymers, including one at two temperatures and one at two plasticizer concentrations. The correlation is only possible when the TCH values for all of the motional environments within the polymers are considered. An inversion recovery cross polarization (IRCP) NMR technique is used to obtain motional and morphological information from the main chain carbons of each polymer. After comparing simplified correlation functions for the two parameters, an experimental relationship between them is established that suggests that TCH and E' are both modulated by a similar distribution of molecular motions.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1990.070400926
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  • 6
    Electronic Resource
    Electronic Resource
    Studies of thermal transition behavior in plasticized poly(vinyl butyral-co-vinyl alcohol) with solid-state NMR and thermal analysis techniques (1992)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 46 (1992), S. 295-301 
    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: Samples of plasticized poly(vinyl butyral-co-vinyl alcohol) (PVB) are found to exhibit multiple thermal transitions as observed by dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC). Arrhenius plots using DSC and DMA data suggest that two of the transitions are glass-type ones. Variable temperature solid-state 13C-NMR experiments show a temperature-dependent line-broadening pattern for all PVB backbone carbons with maximum broadening at 55°C or at about 50°C above the second-order-type transitions α1 and α2 as measured by DSC. Using Arrhenius plots, the NMR transition is found to best correlate with α1, which is consistent with glass transition behavior. The solid-state NMR spectra also show that vinyl alcohol tacticity remains unresolved up to a temperature of about 95°C, beyond which line narrowing begins to occur. High-temperature thermal transitions are also observed by DSC and DMA, which suggest that the onset of motion involving vinyl alcohol sequences may be responsible for these transitions.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1992.070460210
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  • 7
    Electronic Resource
    Electronic Resource
    NMR and sedimentation studies of a polymeric steric stabilizer for alumina (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 47 (1993), S. 1999-2003 
    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 sedimentation behavior of alumina powder has been studied in the presence of poly-vinylpyrrolidone (PVP) and poly(vinylpyrrolidone-co-vinyl acetate) (PVP/VA) in both thermodynamically “good” and “poor” solvents for the PVP homopolymer. PVP/VA provides higher sediment densities than does its PVP homopolymer counterpart. Solutionstate 13C-T1 spin-lattice relaxation measurements were made on analogous mixtures both with and without alumina powder. The NMR results suggest that the PVP/VA copolymer is anchored to the alumina powder surface by means of VA moieties, whereas the PVP moieties extend into the continuous phase of the slurry medium. Thus, the higher settling densities that are observed in the presence of PVP/VA can be attributed to a steric stabilization mechanism. © 1993 John Wiley & Sons, Inc.
    Additional Material: 1 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070471110
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  • 8
    Electronic Resource
    Electronic Resource
    A relationship between NMR cross-polarization rates and dynamic storage modulae of polymers (1993)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 48 (1993), S. 677-681 
    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 relationship between dynamic storage modulus (E′) and the mean cross-polarization time constants 〈TCH〉 for 16 polymer data sets has been established by using a standard linear solid model. This model is used in an attempt to equate the process of cross-polarization with mechanical rigidity by virtue of the implicit dependence of each phenomenon on molecular motion. The apparent validity of the relationship between these parameters indicates that cross-polarization in polymers can be a function of molecular motion in addition to microscopic spin dynamics. The limitations as well as practical applications of this relationship are discussed. © 1993 John Wiley & Sons, Inc.
    Additional Material: 2 Ill.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1002/app.1993.070480410
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  • 9
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    NMR studies of plasticizer motions in a polymer matrix (1992)
    American Chemical Society
    Details
    Publication Date: 1992-06-01
    Print ISSN: 0024-9297
    Electronic ISSN: 1520-5835
    Topics: Chemistry and Pharmacology , Physics
    Published by American Chemical Society
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  • 10
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    Microbial biomass and activities associated with subsurface environments contaminated with chlorinated hydrocarbons (1988)
    Taylor & Francis
    Details
    Publication Date: 1988-01-01
    Print ISSN: 0149-0451
    Electronic ISSN: 1521-0529
    Topics: Biology , Geosciences
    Published by Taylor & Francis
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