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  • voids  (2)
  • Central American Seaway  (1)
  • 1
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    High Precision Femtosecond Laser Ablation ICP‐MS Measurement of Benthic Foraminiferal Mn‐Incorporation for Paleoenvironmental Reconstruction: A Case Study From the Plio‐Pleistocene Caribbean Sea (2022)
    Details
    Publication Date: 2023-01-21
    Description: Closure of the Central American Seaway (CAS) and hydrology of the Caribbean Sea triggered Northern Hemisphere Glaciation and played an important role in the Pliocene to modern‐day climate re‐establishing the deep and surface ocean currents. New data on Mn/Ca obtained with femtosecond laser ablation inductively coupled plasma mass spectrometry on well‐preserved tests of the epibenthic foraminifer Cibicidoides wuellerstorfi and infaunal C. mundulus contribute to the interpretation of paleoenvironmental conditions of the Caribbean Sea between 5.2 and 2.2 Ma (million years) across the closure of the CAS. Hydrothermal activity at the Lesser Antilles may be a primary source of Mn in the well‐oxygenated Plio‐Pleistocene Caribbean Sea. Incorporation of Mn in the benthic foraminifer shell carbonate is assumed to be affected by surface ocean nutrient cycling, and may hence be an indicator of paleoproductivity.
    Description: Plain Language Summary: The closure of the Panama Isthmus caused the expansion of ice sheets in the Northern Hemisphere and changed the water current dynamics and climate in the Caribbean Sea since the Pliocene (∼5.3 million years ago). New Mn/Ca data measured using femtosecond laser ablation inductively coupled plasma mass spectrometry on the deep‐sea benthic foraminifer species Cibicidoides wuellerstorfi and Cibicidoides mundulus help us understand past environmental conditions of the Caribbean Sea prevailed between 5.2 and 2.2 million years ago. While manganese might be sourced from the surrounding hydrothermal vents, its incorporation in the foraminifer shell carbonate might be related to nutrient cycling and may indicate past biological productivity in the ocean.
    Description: Key Points: Femtosecond‐laser ablation inductively coupled plasma mass spectrometry provides a new approach on distinguishing Mn of the ontogenetic shell calcite from Mn of the authigenic coatings. Ontogenetic Mn within the foraminifer shell calcite may result from the regional nutrient cycle. Mn in the deep eastern Caribbean Sea may mainly derive from hydrothermal sources along the Antilles Island Arc.
    Description: MPIC
    Description: https://doi.org/10.17632/bps7nw7922.1
    Keywords: ddc:560 ; manganese ; Cibicidoides wuellerstorfi ; Cibicidoides mundulus ; Central American Seaway ; trace elements ; hydrothermal ; paleoproductivity
    Language: English
    Type: doc-type:article
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  • 2
    Electronic Resource
    Electronic Resource
    Dielectric relaxation of ball-like labels in polyisoprene (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 17-24 
    Details
    ISSN: 1435-1536
    Keywords: Dielectric measurements ; label ; polyisoprene ; ball-like molecules ; glass process ; local process ; voids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ball-like molecules with strong dipoles (labels) were mixed with synthetic polyisoprene (IR305) in low concentrations (〈1%) and measured dielectrically in the frequency range 10−2–107 Hz and the temperature range −70–0°C (glass relaxation region). Calorimetric measurements showed that this type of label has a plasticizing effect on the polymeric matrix. The dielectric measurements showed that these ball-like molecules relax through cooperative rotations with the polymeric segments and at the same relaxation frequency. In addition, the label molecules showed a high-frequency local relaxation process. The relaxation strength ratio of the local process (X local) to the total relaxation strength of the label was found to be dependent on the volume as well as on the shape of the label. A comparison between the relaxation behaviors of the ball-and rod-like molecules, having the same volume, showed that the length of the label is also an important parameter for the determination of the local contribution as well as of the cooperative relaxation mechanism of the label. The label relaxation process is discussed in relation to the molecular packing of the host polymer.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00653306
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  • 3
    Electronic Resource
    Electronic Resource
    On the dielectric glass relaxation process of polymers: Ball-like labels in polystyrene (1994)
    Springer
    Colloid & polymer science 272 (1994), S. 25-35 
    Details
    ISSN: 1435-1536
    Keywords: Dielectric relaxation ; label ; polystyrene ; ball-like molecules ; glass process ; voids
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract Ball-like molecules with strong dipoles (labels) were mixed with technical polystyrene (PS168N) in low concentrations (〈0.5% wt) and measured dielectrically in the frequency range 10−2–107 Hz, and the temperature range 100°–135°C (glass relaxation region). The measurements showed that these ball-like molecules relax cooperatively with the polymeric segments with relaxation times lying at the high-frequency tail of the glass process. The activation energy of the main label process is found to be very similar to that of the glass process of the polystyrene segments and also has the same temperature dependence. This finding implies the existence of an additional mode of relaxation in the dielectric spectrum of the glass process of polystyrene (compared to polyisoprene). Considering the different behavior of the ball-like molecules in polystyrene and polyisoprene and the temperature dependence of the half-width of dielectric loss peak in different polymers, we suggest that the polymers could be classified into three classes according to the available dielectric relaxation modes in the glass process. In addition, the label molecules showed a high-frequency local relaxation process. The relaxation strength ratio of the local process (X local) to the total relaxation strength of the label was found to be dependent on the volume of the label. This phenomenon could supply a new method for the determination of the mean size of the holes (voids) representing the free volume of the host matrix.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00653307
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