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  • 1995-1999  (3)
  • 21.10.−K  (1)
  • Anhydrous ammonia  (1)
  • ETS-10  (1)
  • 1
    ISSN: 1572-879X
    Keywords: ETS-10 ; TS-1 ; Ti-β ; EXAFS ; XANES ; X-ray ; UV ; methanol ; 2-propanol
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract We report here the first structural characterization by Ti K-edge EXAFS and XANES of ETS-10 and aluminum-free Ti-β molecular sieves. A TS-1 sample was also studied for comparison. The near-edge spectrum of TS-1 revealed an intense pre-edge feature characteristic of Ti atoms in tetrahedral coordination. However, the pre-edge peak for ETS-10 was quite small and shifted in energy, which is consistent with the known octahedral structure surrounding Ti atoms in the material. Analysis of the EXAFS for ETS-10 revealed an average Ti-O interatomic distance of 2.00 +- 0.01 Å which is longer than the Ti-O distance (1.95Å) in anatase TiO2. For Ti-β, an intense pre-edge peak is present in the near-edge spectrum and the intensity, energy and width of this peak are the same as for TS-1. In addition, the average Ti-O interatomic distance in Ti-β and TS-1 was 1.80 +- 0.01 Å, which is significantly shorter than the distance measured in ETS-10. The EXAFS and XANES results indicate that the Ti sites in aluminum-free Ti-β are structurally identical to the tetrahedral sites in TS-1. This conclusion is supported by the similarity of the UV absorption thresholds for the two samples. X-ray absorption spectra were also recorded with methanol or 2-propanol adsorbed on the Ti-β and TS-1 molecular sieves. Alcohol adsorption decreased the intensity and broadened the Ti pre-edge peak for both samples, demonstrating a local chemical interaction with the Ti sites. Methanol adsorption lengthened the average Ti-O bond to 1.83 ± 0.01 Å. The similarity of the X-ray absorption spectra for aluminum-free Ti-β and TS-1 in the presence of alcohols suggests that the Ti sites in the two frameworks are chemically indistinguishable for vapor-phase adsorption of alcohols at low concentrations.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1434-601X
    Keywords: 21.10.−K ; 27.80.+W
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract The high-spin states in197Bi have been studied with the187Re(16O, 6n)197Bi reaction at16O energies between 85 and 105 MeV. In-beam measurements ofγ-ray excitation functions,γ-γ-t coincidences and γray angular distributions were carried out with 6 BGO(AC) HPGe detectors and one intrinsic Ge planar detector. 11 new transitions and 3 new isomers at 2089, 2357 and 1968+Δ keV with t1/2 =19.3±4.9, 53.4±20.5 and 18.0±3.1 ns., respectively, were observed, and a level scheme is established. Some differences between the present work and the previous results were found.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Springer
    Biology and fertility of soils 19 (1995), S. 10-14 
    ISSN: 1432-0789
    Keywords: Water quality ; Water-soluble C ; N fertilizer Atrazine ; Anhydrous ammonia ; Ridge tillage system
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract The transport of anhydrous NH3-solubilized soil organic matter from surface to subsurface soils may affect subsurface microbial activity. In the present study we determined the impact of anhydrous NH3-N fertilizer on organic C solubilization and the propensity of solubilized C to leach with percolating water. In fertilized treatments, anhydrous NH3 was subsurface-banded at 20g N m-2 in ridge or valley areas of a ridge tillage system. In contol treatments, 0g N m-2 was banded into the valley area of a ridge tillage system. Rainfall (17 cm) was applied with a drop-type artificial rainfall simulator 3, 10, and 24 days after the fertilizer application. The treatments were replicated twice. Grid lysimeters (15 by 15 cm) were placed 75 cm below the soil surface of a Brandt silty clay loam (fine-silty over sandy or sandy skeletal mixed Pachic Udic Haploboroll). Lysimeters were used to collect percolating water temporally and spatially. The application of N fertilizer increased dissolved organic C concentrations in percolating water when rainfall was applied 3 days after the fertilizer application. However, when the rainfall was applied 24 days after the fertilizer application the dissolved organic C concentrations in percolating water was not influenced by anhydrous NH3 application. The smaller dissolved organic C concentrations in percolating water with a longer incubation time were most likely the result of microbial assimilation or respiration of solubilized C.
    Type of Medium: Electronic Resource
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