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  • 1
    Electronic Resource
    Electronic Resource
    Evaluation of microcrystalline cellulose. I. Changes in ultrastructural characteristics during preliminary acid hydrolysis (1996)
    New York, NY [u.a.] : Wiley-Blackwell
    Journal of Applied Polymer Science 59 (1996), S. 483-488 
    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: Several microcrystalline celluloses prepared from viscose staple, bagasse, ramie, and cotton were evaluated by viscosimetry, X-ray diffraction and scanning and transmission electron microscopies. The changes in crystallinity, size of crystallites, grain-size distribution, morphological features, and degree of polymerization were found to be dependent on and greatly limited by the polymorphic conformations of cellulose. These changes were more conspicuous in cellulose II than in cellulose I. The coexistence of a two-phase system still remains in all the specimens of microcrystalline cellulose powders. Combining the findings with respect to the extent of the changes in the size of crystallites, it appears inevitable that recrystallization in some of the defective crystallites and degradation in the disordered areas of cellulose occurs simultaneously in the preliminary hydrolysis process during the production of microcrystalline cellulose. © 1996 John Wiley & Sons, Inc.
    Additional Material: 3 Ill.
    Type of Medium: Electronic Resource
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  • 2
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    Seawater carbonate chemistry and viruses,bacteria Abundance and phytoplankton community structure (2021)
    PANGAEA
    Details
    Publication Date: 2024-05-22
    Description: Eutrophic coastal regions are highly productive and greatly influenced by human activities. Primary production supporting the coastal ecosystems is supposed to be affected by progressive ocean acidification driven by increasing CO2 emissions. In order to investigate the effects of high pCO2 (HC) on eutrophic plankton community structure and ecological functions, we employed 9 mesocosms and carried out an experiment under ambient (410 ppmv) and future high (1000 ppmv) atmospheric pCO2 conditions, using in situ plankton community in Wuyuan Bay, East China Sea. Our results showed that HC along with natural seawater temperature rise significantly boosted biomass of diatoms with decreased abundance of dinoflagellates in the late stage of the experiment, demonstrating that HC repressed the succession from diatoms to dinoflagellates, a phenomenon observed during algal blooms in the East China Sea. HC did not significantly influence the primary production or biogenic silica contents of the phytoplankton assemblages. However, the HC treatments increased the abundance of viruses and heterotrophic bacteria, reflecting a refueling of nutrients for phytoplankton growth from virus-mediated cell lysis and bacterial degradation of organic matters. Conclusively, our results suggest that increasing CO2 concentrations can modulate plankton structure including the succession of phytoplankton community and the abundance of viruses and bacteria in eutrophic coastal waters, which may lead to altered biogeochemical cycles of carbon and nutrients.
    Keywords: Ammonium; Aragonite saturation state; Bacteria; Bicarbonate ion; Biogenic silica; Calcite saturation state; Calculated using seacarb after Nisumaa et al. (2010); Carbon, inorganic, dissolved; Carbonate ion; Carbonate system computation flag; Carbon dioxide; Cell density; Chlorophyll a; Coast and continental shelf; Community composition and diversity; Day of experiment; Entire community; EXP; Experiment; Field experiment; Fugacity of carbon dioxide (water) at sea surface temperature (wet air); Mesocosm or benthocosm; Night period respiration, carbon; Nitrate; Nitrite; North Pacific; OA-ICC; Ocean Acidification International Coordination Centre; Partial pressure of carbon dioxide (water) at sea surface temperature (wet air); Pelagos; pH; Phosphate; Primary production, carbon assimilation; Primary production/Photosynthesis; Replicates; Respiration; Salinity; Silicate; Temperate; Temperature, water; Treatment; Type; Viral abundance; Wuyuan_Bay_OA
    Type: Dataset
    Format: text/tab-separated-values, 6225 data points
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  • 3
    Electronic Resource
    Electronic Resource
    Superconducting properties and crystal structures of single-crystal niobium nitride thin films deposited at ambient substrate temperature (1996)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 79 (1996), S. 7837-7842 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Single-crystal niobium nitride (NbN) thin films were fabricated at ambient substrate temperature so that photoresist lift-off techniques could be used in fabricating Josephson tunnel junctions. In this article, we describe the superconducting properties and crystal structure of the NbN films. Even though the substrates were not heated, the NbN films had excellent superconducting properties: a high Tc of 16 K, low normal-state resistivity (ρ20=62 μΩ cm), and residual resistivity ratios RRR=ρ300/ρ20 above one. The film structures, which were investigated by x-ray diffraction, electron diffraction patterns and transmission electron micrographs, show a single-phase orientation without columnar and granular structures. We have found that the superconducting properties depend on the lattice parameter, and the best films had a lattice parameter of 0.446 nm. NbN/AlN/Nb tunnel junctions were fabricated to measure the superconducting energy gap of the NbN films. We estimated the energy gap ΔNbN to be 2.6 meV and the magnetic penetration depth λNbN to be 176 nm. © 1996 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.362392
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  • 4
    Electronic Resource
    Electronic Resource
    Chain Dimensions in Amorphous Polymer Melts (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 570-576 
    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/ma00106a022
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  • 5
    Electronic Resource
    Electronic Resource
    Aggregation (micellization) of associating polymers (1990)
    s.l. : American Chemical Society
    Langmuir 6 (1990), S. 928-934 
    Details
    ISSN: 1520-5827
    Source: ACS Legacy Archives
    Topics: Chemistry and Pharmacology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/la00095a007
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  • 6
    Electronic Resource
    Electronic Resource
    Fabrication and characterization of epitaxial NbN/MgO/NbN Josephson tunnel junctions (2001)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 90 (2001), S. 4796-4799 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: We fabricated epitaxial NbN/MgO/NbN Josephson tunnel junctions with good tunneling characteristics in the range of JC=0.2–70 kA/cm2. The counter and base NbN electrodes of the tunnel junctions had the same TC and 20 K resistivity at about 15.7 K and 60 μΩ-cm, respectively. X-ray analysis showed that all the layers that formed the tunnel junctions grew epitaxially. In the range of JC=0.2–15 kA/cm2, the tunnel junctions fabricated had large gap voltages (5.6–5.9 mV), narrow gap widths (less than 0.1 mV), high ICRN products (2.6–3.8 mV), and small subgap leakage current (Vm=40–96 mV). © 2001 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1409583
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  • 7
    Electronic Resource
    Electronic Resource
    Optical bistability in two-dimensional nonlinear optical superlattice with two incident waves (1995)
    Woodbury, NY : American Institute of Physics (AIP)
    Applied Physics Letters 67 (1995), S. 3538-3540 
    Details
    ISSN: 1077-3118
    Source: AIP Digital Archive
    Topics: Physics
    Notes: With two coherent waves incident to a two-dimensional (2D) nonlinear optical superlattice containing Kerr form dielectric nonlinearity, the optical bistability related to transition between a forbidden transmission state and an allowed transmission state can occur through the index-modulation mechanism. This kind of bistability is difficult to obtain in the case of only one incident wave. The power cost for the bistability might be very low. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.114913
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  • 8
    Electronic Resource
    Electronic Resource
    Polymers with excluded volume in various geometries: Renormalization group methods (1987)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 86 (1987), S. 4266-4279 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: Renormalization group (RG) methods are generalized to study a single polymer chain with excluded volume in various geometries with different boundary conditions (or polymer–surface interactions) on the limiting surfaces. Methods for the renormalization of these theories are presented and are used to derive the RG equations which dictate the generalized scaling behavior as a function of the several interaction and geometrical parameters. We illustrate the general theory by studying a polymer chain confined between two parallel plates with three different (Neumann, Dirichlet, and periodic) boundary conditions to one-loop order. We show that ε expansions are well behaved as long as the radius of gyration of the chain is smaller than the interplate separation L. The finite size corrections to the full space (bulk) limit are found to be proportional to L−1 for free boundaries, while they are exponentially small for periodic boundary conditions. The presence of several lengths and/or interactions produces interesting crossovers, which we illustrate for a Gaussian polymer chain attached to the exterior surface of a repulsive sphere where full crossover scaling functions are obtained for the partition function and moments of the end-vector distribution function. A new exponent associated with the radius of the sphere is predicted on the basis of scaling arguments which are supported by the RG equations. This work provides the necessary input ingredients for extension of the theory to treat semidilute concentrations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451887
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  • 9
    Electronic Resource
    Electronic Resource
    Nucleation in binary polymer blends: A self-consistent field study (2002)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 116 (2002), S. 2289-2300 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: We study the structure and thermodynamics of the critical nuclei in metastable binary polymer blends using the self-consistent field method. At the mean-field level, our results are valid throughout the entire metastable region and provide a smooth crossover from the classical capillary-theory predictions near the coexistence curve to the density functional predictions of Cahn and Hilliard (properly transcribed into expressions involving the parameters of the binary polymer blends) near the spinodal. An estimate of the free energy barrier provides a quantitative criterion (the Ginzburg criterion) for the validity of the (mean-field) self-consistent approach. The region where mean-field theory is valid and where there can be a measurable nucleation rate is shown to be poorly described by the existing limiting theories; our predictions are therefore most relevant in this region. We discuss our results in connection with recent experimental observations by Balsara and co-workers. © 2002 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1429956
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  • 10
    Electronic Resource
    Electronic Resource
    Interaction of a polymer chain with an asymmetric liquid–liquid interface (1986)
    College Park, Md. : American Institute of Physics (AIP)
    The Journal of Chemical Physics 85 (1986), S. 3068-3077 
    Details
    ISSN: 1089-7690
    Source: AIP Digital Archive
    Topics: Physics , Chemistry and Pharmacology
    Notes: A continuum model is presented for polymer chains near an asymmetric (A–B) liquid–liquid interface where each side of the interface can have different polymer–surface interactions. For example, one side can attract the macromolecule, while the other can repel it. The model contains different monomer free energies and different excluded volume interactions for the macromolecule in the two solvents. The model is solved exactly in the ideal limit where excluded volume vanishes in order to illustrate qualitatively the wide range of possible behavior. We evaluate the fixed end-vector distribution, some moments of this distribution, and discuss other distributions and several interesting limiting cases. This rich model is constructed based on physical considerations and on consistency requirements which are imposed on any zeroth-order model when it is used in conjunction with renormalization group methods to incorporate the excluded volume interactions.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.451014
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