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  • Wiley  (48)
  • American Physical Society  (32)
  • Wiley-Blackwell  (27)
  • International Union of Crystallography (IUCr)
  • 1995-1999  (108)
  • 1975-1979
  • 1998  (108)
  • 1
    ISSN: 0006-3592
    Keywords: solar irradiance ; tubular photobioreactor ; microalgal culture ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A macromodel is developed for estimating the year-long biomass productivity of outdoor cultures of microalga in tubular photobioreactors. The model evaluates the solar irradiance on the culture surface as a function of day of the year and the geographic location. In a second step, the geometry of the system is taken into account in estimating the average irradiance to which the cells are exposed. Finally, the growth rate is estimated as a function of irradiance, taking into account photoinhibition and photolimitation. The model interconnects solar irradiance (an environmental variable), tube diameter (a design variable), and dilution rate (an operating variable). Continuous cultures in two different tubular photobioreactors were analyzed using the macromodel. The biomass productivity ranged from 0.50 to 2.04 g L-1 d-1, and from 1.08 to 2.76 g L-1 d-1, for the larger and the smaller tube diameter photobioreactors, respectively. The quantum yield ranged from 1.1 to 2.2 g E-1; the higher the incident solar radiation, the lower the quantum yield. Simultaneous photolimitation and photoinhibition of outdoor cultures was observed. The model reproduced the experimental results with less than 20% error. If photoinhibition was neglected, and a growth model that considered only photolimitation was used to fit the data, the error increased to 45%, thus reflecting the inadequacy of previous outdoor growth models that disregard photoinhibition. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 58: 605-616, 1998.
    Additional Material: 9 Ill.
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  • 2
    Publication Date: 1998-05-08
    Print ISSN: 0014-5793
    Electronic ISSN: 1873-3468
    Topics: Biology , Chemistry and Pharmacology
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  • 3
    Publication Date: 1998-08-01
    Print ISSN: 0001-1541
    Electronic ISSN: 1547-5905
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Published by Wiley on behalf of American Institute of Chemical Engineers.
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  • 4
    ISSN: 1600-5775
    Source: Crystallography Journals Online : IUCR Backfile Archive 1948-2001
    Topics: Geosciences , Physics
    Notes: The ESRF magnetic scattering beamline has been optimized for easy tunability of the polarization and energy in the 3–40 keV range. The linear horizontal polarization from the undulator reaches 99.9%, with a flux of ∼1012 photons s−1 at the sample. The diffractometer can operate in horizontal and vertical geometries, with an energy or polarization analyser. The capabilities of this beamline in terms of flux, energy tunability and polarization, permitted polarization analysis of resonant magnetic scattering from antiferromagnetic UPd2Si2 at both the L2- and M4-edges of uranium, to separate the contributions of the 5f and 6d electrons to the magnetism.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Journal of Physical Organic Chemistry 11 (1998), S. 321-333 
    ISSN: 0894-3230
    Keywords: metal-catalyzed carbenoid reactions ; iodonium ylides ; sulfonium ylides ; Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Physics
    Notes: Transition metal-catalyzed decomposition of phenyliodonium and diphenylsulfonium ylides was investigated with regard to application in asymmetric carbenoid reactions. Phenyliodonium ylides react in the presence of Rh(II) catalysts with the same selectivity in inter- and intramolecular cyclopropanations as the corresponding diazo compounds, and intramolecular CH insertions proceed with identical enantioselectivities. With diphenylsulfonium ethoxycarbonylmethylide the Cu(I)-catalyzed cyclopropanation of olefins affords trans/cis ratios and asymmetric inductions identical with those of diazo compounds, but with Rh(II) catalysts some small, although significant, selectivity variations occur, which are ascribed to coordination of diphenyl sulfide to one of the coordination sites of the catalyst. © 1998 John Wiley & Sons, Ltd.
    Additional Material: 2 Ill.
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  • 6
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 351-357 
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: The activation of the (110) TiO2 rutile surface by deposition of alkali metal atoms has been the subject of some recent experimental studies. These results indicate a reduction of the surface when sodium atoms are deposited on it. In the present work, this process has been studied by means of ab initio embedded cluster calculations combined with molecular dynamics simulations. Several surface sites have been considered and our calculations show that reduction occurs selectively on fivefold coordinated titanium atoms. Geometry optimization of a representative Na-surface clusters leads to a structure in which the Na atom is symmetrically coordinated to three oxygen atoms (two protruded and one basal) in excellent agreement with models proposed from experimental data. A mechanism for the adsorption process in which a long-distance electron transfer from atomic Na toward a fivefold coordinated surface titanium atom followed by physisorption of the Na+ cation on the surface is proposed.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 351-357, 1998
    Additional Material: 4 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY : Wiley-Blackwell
    International Journal of Quantum Chemistry 70 (1998), S. 359-365 
    ISSN: 0020-7608
    Keywords: Chemistry ; Theoretical, Physical and Computational Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Notes: A theoretical analysis of γ-Al2O3 (110) surface hydroxylation based on ab initio Hartree-Fock embedded cluster calculations was carried out. Both tetrahedral and octahedral Al sites were considered. These sites were modeled by a series of clusters of increasing size: Al8O3, Al12O5, and Al16O8, embedded in an array of point charges. The adsorption of water was found to be dissociative or nondissociative depending on the cluster size, although the mechanism clearly converges toward dissociation for the more reliable models in agreement with the experiment. This dependence can be explained in light of the basicity modification of surface oxide ions induced by the environment as well as by surface relaxation. Comparison of chemisorption energies suggests that the preferred site for hydroxylation is a low coordination tetrahedral aluminum.   © 1998 John Wiley & Sons, Inc. Int J Quant Chem 70: 359-365, 1998
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 59 (1998), S. 144-155 
    ISSN: 0006-3592
    Keywords: lysozyme ; protein precipitation ; thiocyanate ; hydrogen exchange ; nuclear magnetic resonance ; protein unfolding ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: We have employed nuclear magnetic resonance (NMR) measurements of hydrogen exchange to identify residue-level conformational changes in hen egg white lysozyme (HEWL) as induced by salt precipitation. Deuterated HEWL was dissolved into a phosphate (H2O) buffer and precipitated at pH 2.1 upon addition of solid KSCN or (ND4)2SO4, allowing isotope labeling of unfolded regions. After 1 h, each precipitate was then dissolved at pH 3.8 to initiate refolding and preserve labeling and subsequently purified for NMR analysis. HEWL precipitated by 1.0 M KSCN exhibited increased hydrogen exchange at 14 residues out of 42 normally well-protected in the native state. Of the affected residues, 9 were situated in the β-sheet/loop domain. A similar, though less extensive, effect was observed at 0.2 M KSCN. Precipitation by 1.2 M (ND4)2SO4 resulted in none of the changes detected with KSCN. The popularity of ammonium sulfate as a precipitant is thus supported by this observed preservation of structural integrity. KSCN, in comparison, produced partial unfolding of specific regions in HEWL due most likely to known preferential interactions between -SCN and proteins. The severity of unfolding increased with KSCN concentration such that, at 1.0 M KSCN, almost the entire β-sheet/loop domain of HEWL was disrupted. Even so, a portion of the HEWL core encompassed by three α-helices remained intact, possibly facilitating precipitate dissolution. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 59: 144-155, 1998.
    Additional Material: 6 Ill.
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  • 9
    ISSN: 0006-3592
    Keywords: protein-protein affinity chromatography ; dextrans as spacer arms ; adsorption of immunoglobulins on protein A ; hydrolysis of casein by rennin ; immobilized protein A ; immobilized rennin ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: New dextran-agarose supports, suitable for covalent immobilization of enzymes and proteins acting on macromolecular substrates, were prepared. The thick internal fibers of agarose gels were covered by a low-density layer of long, flexible, hydrophilic, and inert dextran molecules. Rennin and protein A were immobilized on these novel supports and the resulting derivatives exhibited a very high capacity for biological recognition of soluble macromolecular substrates. Caseinolytic activity of this immobilized enzyme was 15-fold higher than activity of directly immobilized rennin, through short spacer arms, on agarose gels. Similarly, the new derivatives of immobilized protein A were able to adsorb up to 2 molecules of immunoglobulin per each molecule of immobilized protein A. When the immobilized proteins were secluded away from the support surface by using these new long and hydrophilic spacer arms, they exhibit minimal steric hindrances that could be promoted by the proximity of the support surface. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 60: 518-523, 1998.
    Additional Material: 3 Ill.
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  • 10
    ISSN: 0006-3592
    Keywords: hybridoma ; futile cycling ; hollow fiber bioreactor ; glutamine ; NMR ; C-13 ; Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: The effect of changes in extracellular glutamine level on metabolism of a murine hybridoma was examined with in vivo nuclear magnetic resonance (NMR) spectroscopy. Cells were cultured in a hollow-fiber bioreactor at high cell density to allow intracellular metabolite levels to be determined on a metabolically relevant time scale. Steady infusions of [1-13C] glucose were used to label glycolytic and tricarboxylic acid cycle intermediates, which permitted continuous monitoring with NMR spectroscopy during changes in environmental glutamine level. Samples of the extracellular medium were also analyzed to determine the effect of glutamine on other metabolites associated with primary and secondary metabolism. The changes in glutamine concentration had several effects on primary and secondary metabolism, depending on the rate the changes were made. For a brief reduction in feed glutamine concentration from 4 to 0 mM (which produced a rapid change from 0.67 to ∼0 mM in residual glutamine), large changes were observed in the rate of consumption of metabolites normally associated with energy production. Antibody synthesis was strongly stimulated and nitrogen metabolism was significantly altered. For a more prolonged reduction from 2.4 to 1.2 mM (which produced a slower reduction from 0.30 to 0.08 mM in residual glutamine), much smaller changes were observed even though the concentration of glutamine at the reduced feed level was very low. Energy metabolism did not appear to be limited by glutamine at 0.08 mM, which suggests that significant futile cycling may occur in energy producing pathways when excess glucose and glutamine are available. However, this concentration of extracellular glutamine appeared to affect some anabolic pathways, which require amino groups from glutamine. © 1998 John Wiley & Sons, Inc. Biotechnol Bioeng 57: 172-186, 1998.
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