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  • 1
    Electronic Resource
    Electronic Resource
    Springer
    Marine biology 136 (2000), S. 979-986 
    ISSN: 1432-1793
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract Opsonins, a group of serum proteins present in vertebrates, are known to bind to the surface of many kinds of pathogens and tag them as targets for phagocytosis. Opsonin-like molecules have been suggested to exist in several invertebrates. In this paper, we report the discovery of a new opsonin-like molecule in the coelomic fluid of the sea cucumber Holothuria leucospilota. Opsonic activity in cell-free coelomic fluid was characterized by sodium dodecyl sulfate–polyacrylamide gel electrophoresis, two-dimensional electrophoresis and gel filtration. Phagocytic uptake of yeast cells and latex beads by amoebocytes was quantified by microscopic analysis. It was found that a 20 kdalton protein bound to and enhanced phagocytosis of heat-killed yeast cells. The results of Western blot analysis suggest that both amoebocytes and spherule cells produce this opsonin-like molecule.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1432-184X
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract The response of a glucose-fed anaerobic chemostat community to a long-term (〉200 days) periodic substrate perturbation was examined. Identical steady-state communities were established in a ``mother'' and a ``daughter'' reactor at pH 7, 35°C, inlet glucose concentration of 8 g l−1, and dilution rate of 0.1 day−1. After reaching steady state, the daughter reactor was subjected to a periodic organic loading pattern in which the influent glucose concentration was alternately varied from 16 g l−1 to 0 g l−1 (mineral media only) on a 2-day cycle (1 day at 16 g l−1 followed by 1 day without glucose feed). The average organic loading rate for the perturbation cycle was equal to the steady-state glucose loading rate of 0.8 g l−1 day−1. The dilution rate of the daughter reactor was constant at 0.1 day−1 throughout the perturbation period. A rapid accumulation in volatile fatty acids (VFAs) occurred immediately after initiating the perturbation. During the first 45 days, effluent acetate, propionate, and butyrate concentrations increased to ca. 2,500, 800, and 1,200 mg l−1, respectively; effluent chemical oxygen demand (COD) increased from 450 mg l−1 to 5,200 mg l−1. Total gas production decreased from about 600 ml day−1 to an average value of 290 ml day−1; CH4 content of the biogas decreased from 50% to about 30%; and the pH decreased from 7.0 to 6.4. This was followed by a 60-day metastable ``steady'' state during which time the effluent COD and VFA concentrations fluctuated about new median values. A dramatic change in the fermentation products of glucose was observed. At the end of the metastable period, VFA concentrations decreased rapidly. First, a rapid decrease in butyrate concentration occurred. Subsequently, acetate and propionate concentrations decreased to near the original preperturbation steady-state levels. Within ca. 30 days, a new steady state was established. These observations demonstrate that the anaerobic system was able to adapt to the periodic substrate perturbation through a long-term change in community structure. This conclusion was verified by comparison of DNA extracts from the steady-state control ``mother'' reactor with extracts from the perturbed ``daughter'' reactor, changes in substrate degradation rates, and microscopic examination.
    Type of Medium: Electronic Resource
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  • 3
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochimica et Biophysica Acta (BBA)/Biomembranes 1106 (1992), S. 227-232 
    ISSN: 0005-2736
    Keywords: Bilayer ; Gramicidin A ; Monte Carlo simulation ; NMR
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Medicine , Physics
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 0375-9474
    Keywords: Nuclear reactions
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Physics
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Biochemical and Biophysical Research Communications 165 (1989), S. 1-6 
    ISSN: 0006-291X
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Archives of Biochemistry and Biophysics 313 (1994), S. 229-234 
    ISSN: 0003-9861
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Biology , Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Amsterdam : Elsevier
    Journal of Luminescence 57 (1993), S. 147-151 
    ISSN: 0022-2313
    Source: Elsevier Journal Backfiles on ScienceDirect 1907 - 2002
    Topics: Chemistry and Pharmacology , Physics
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1432-1114
    Source: Springer Online Journal Archives 1860-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: Abstract We investigate the behaviour of a liquid jet stimulated by pressure disturbances using a photometric measurement of the jet shadow width. Two apparatuses involving lights of different nature are utilized and measurements are taken from the exit of the nozzle to drop breakoff for different operating conditions. Fourier analysis is applied to characterize the spatial evolution of the jet shape. In contrast to previous studies where only amplitudes of the Fourier modes are reported, phase shifts are also recovered for low and high initial perturbations. We show that the spatial reconstruction of the jet from the temporal Fourier analysis at different abscissae is in excellent agreement with the experimental profiles
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    International Journal for Numerical Methods in Fluids 23 (1996), S. 1043-1072 
    ISSN: 0271-2091
    Keywords: lee-waves ; seamount ; turbulence-energy ; mixing ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
    Notes: A three-dimensional, primitive equation, baroclinic numerical model incorporating a range of turbulence energy submodels is used to study the generation of internal lee waves over an isolated seamount. Attention is given to the turbulence mixing enhanced by the internal lee waves. The results show that regions of strong turbulence energy appear over the lee side of the seamount associated with the production of the lee waves. The computed vertical eddy viscosity and diffusivity using turbulence models can be as large as 1 m2s-1.A comparison of the magnitude and spatial distribution of the internal lee waves does not reveal any major differences in results computed using different turbulence energy models or mixing determined from a Richards on number formulation. However, the magnitude of the vertical mixing is sensitive to the form of turbulence energy submodel. Also, a study of the relevant importance of the various terms in the turbulence energy equation shows that the term representing the advection of turbulence needs to be retained in order to accurately reproduce the mixing produced by the internal lee waves. Calculations using a range of seamount profiles show that the magnitude of near-bed turbulence is sensitive to the shape of the seamount.The magnitude and spatial distribution of the lee waves and associated flow field are affected by the parametrization of horizontal diffusion, with significant differences between the use of Laplacian and biharmonic forms of horizontal diffusion. The application of biharmonic horizontal diffusion is recommended.
    Additional Material: 20 Ill.
    Type of Medium: Electronic Resource
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