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  • 1
    Electronic Resource
    Electronic Resource
    Atomic force microscopy and high-resolution scanning electron microscopy study of the banded surface morphology of hydroxypropyl cellulose thin films (1995)
    s.l. : American Chemical Society
    Macromolecules 28 (1995), S. 393-395 
    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/ma00105a058
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  • 2
    Electronic Resource
    Electronic Resource
    Mineralization of .alpha.-, .gamma.-, and .beta.-Isomers of Hexachlorocyclohexane by a Soil Bacterium under Aerobic Conditions (1995)
    s.l. : American Chemical Society
    Journal of agricultural and food chemistry 43 (1995), S. 833-837 
    Details
    ISSN: 1520-5118
    Source: ACS Legacy Archives
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Process Engineering, Biotechnology, Nutrition Technology
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1021/jf00051a052
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  • 3
    Electronic Resource
    Electronic Resource
    Nitrification of ammonium in different components of a flooded rice soil system (1996)
    Springer
    Biology and fertility of soils 23 (1996), S. 321-326 
    Details
    ISSN: 1432-0789
    Keywords: Nitrification ; Flooded rice soils ; Rhizosphere ; Rice variety ; Crop growth stage ; Organic amendment
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology , Geosciences , Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition
    Notes: Abstract Nitrification associated with the various components [subsurface soil from unplanted and planted (rhizosphere) fields, standing water and surface soil from planted and unplanted fields and leaf sheath suspensions] of submerged rice paddies was examined in incubation experiments with solutions inoculated with soil or water samples. Substantial nitrification occurred in all samples, standing water and surface soil samples in particular, during their 40-day incubation with NH 4 + −N. Almost all the NH 4 + −N, disappeared during incubation with standing water, was recovered as NO inf3 sup- −N. This, compared to 70–80% from all soil samples and only 29% from leaf sheath suspensions. Significant loss of nitrogen, especially from leaf sheath suspensions, is probably due to nitrification-denitrification as evidenced by its complete recovery in the presence of N-Serve. Nitrification potential of the soil and water samples varied with the crop growth stage and was more pronounced at tillering and panicle inititation stages than at other stages. Nitrification potential of samples from green-manure-amended plots was distinctly less than that of samples from control and urea-amended plots. Most probable number (MPN) estimates of ammonium-oxidizing bacteria were always higher in surface soil in both planted and unplanted plots at all stages of crop growth.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00335961
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  • 4
    Electronic Resource
    Electronic Resource
    Analysis of bifurcations in continuous fermentation using recombinant microorganisms with delayed responses (1995)
    Springer
    Bioprocess and biosystems engineering 12 (1995), S. 199-203 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract When the feed rate to a fermenter is varied periodically in order to favor the growth of plasmid-containing cells, a transition may occur from the starting stationary state to another state. The resulting state may be constant or oscillatory. A generalised model based on the adaption times of plasmid-free and plasmid-harboring cells has been used. Analytical conditions have been derived for bifurcation from one nonoscillatory state to another or to an oscillatory state (Hopf bifurcation). The frequency of oscillation is shown to have an upper bound, which can be controlled by manipulating certain process parameters. The production of tryptophan synthetase by the plasmid pPLc23trpAl in E. coli is used as an example to determine the nature of the Hopf bifurcations.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF01767467
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  • 5
    Electronic Resource
    Electronic Resource
    Incomplete mixing in large bioreactors — a study of its role in the fermentative production of streptokinase (1996)
    Springer
    Bioprocess and biosystems engineering 14 (1996), S. 91-96 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The production of streptokinase in a batch fermentation has been analysed for the role of incomplete macromixing of the broth. The analysis is based on a kinetic model exhibiting inhibition by the substrate and a primary metabolite (lactic acid), and a mixing model comprising two continuous flow reactors (CFRs) with closed-loop recycle. The inoculum is introduced into one region (one CFR) and the mixing process determines its distribution, growth and reactivity. By varying the dilution rates of the CFRs, any degree of macromixing can be simulated. For dilution rates larger than 1.0 h−1 almost complete macromixing is achieved, for which an analogy has been drawn with micromixing. Increasing the volume of the inoculated region relative to the noninoculated region improves the maximum attainable activity of streptokinase and shortens the time for this. In such a situation an imperfectly mixed bioreactor is superior to a perfectly mixed one, implying that good productivity requires a large inoculated region and incomplete macromixing. These inferences are supported by earlier studies of fluid mixing and relaxation times in bioreactors.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00387962
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  • 6
    Electronic Resource
    Electronic Resource
    Start-up sensitivity to the initial state of a batch bioreactor for a recombinant Escherichia coli in a complex medium (1996)
    Springer
    Bioprocess and biosystems engineering 15 (1996), S. 215-219 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract The sensitivities with respect to the initial state of five key variables describing the performance of a batch bioreactor have been computed from an experimentally validated kinetic model. The system has a recombinant Escherichia coli strain containing the plasmid pBR Eco gap, which codes for glyceraldehyde-3-phosphate dehydrogenase (GAPDH) in a complex medium. Since previous studies have shown the start-up sensitivities to be particularly important, the initial 10% of the duration of fermentation was chosen as the time span. The sensitivities of the cell mass, GAPDH and acetate increased with time while those of glucose and yeast extract remained practically constant. Acetate has a crucial role as it functions as both a product and a reactant. With no acetate in the inoculum, the sensitivities of acetate increased an order of magnitude faster than other sensitivities. However, upon addition of acetate through the inoculum, its sensitivities decreased the fastest and stabilised beyond a starting concentration of about 1 g/l whereas other sensitivities stabilised after 5 to 6 g/l of initial acetate. A three-dimensional envelope in the space of acetate concentration-time-relative sensitivity shows a locus of concentrations for minimum time-dependent acetate sensitivity; this may be maintained through fed-batch operation.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00369485
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  • 7
    Electronic Resource
    Electronic Resource
    A heuristic approach to fed-batch optimisation of streptokinase fermentation (1995)
    Springer
    Bioprocess and biosystems engineering 13 (1995), S. 109-112 
    Details
    ISSN: 1432-0797
    Source: Springer Online Journal Archives 1860-2000
    Topics: Process Engineering, Biotechnology, Nutrition Technology
    Notes: Abstract Previous studies have shown that the rate of formation of streptokinase, a secondary metabolite, in batch fermentation is proportional to the specific growth rate of the biomass, which in turn is inhibited by its substrate and the primary product (lactic acid). These kinetics suggest the suitability of fed-batch operation to increase the yield of streptokinase. A near-optimal feed policy has been calculated by the chemotaxis algorithm, and it shows a substrate feed rate decreasing nonlinearly and vanishing after 11 hours. This is followed by batch fermentation for a further 8 hours, at the end of which 12% more streptokinase is generated than by purely batch fermentation. Further improvements in productivity are possible.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00420437
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  • 8
    Electronic Resource
    Electronic Resource
    Apparatus for vortex dynamics studies in high Tc samples using close cycle refrigerator and rf oscillators (1999)
    [S.l.] : American Institute of Physics (AIP)
    Review of Scientific Instruments 70 (1999), S. 1494-1500 
    Details
    ISSN: 1089-7623
    Source: AIP Digital Archive
    Topics: Physics , Electrical Engineering, Measurement and Control Technology
    Notes: The design, fabrication, and performance of an apparatus for measurements of rf penetration depth in superconducting samples are described. The instrument makes use of a close-cycle helium refrigerator and is capable of measuring vortex dynamics in superconducting sample of volume as small as 1×10−3 cm3 with a signal-to-noise ratio of 1400. The system has been tested for a tunnel diode oscillator and an IC 74LS04 oscillator in the 3–5 MHz frequency range. Both magnetic field magnitude and angular variations to the resolution of 1 G and 0.05°, respectively, are possible with the apparatus. The system performance is evaluated by measuring the dynamical behavior of vortices in platelet samples of Bi2Sr2CaCu2O8 and (Bi-Pb)2Sr2Ca2Cu3O10 superconductors. © 1999 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.1149612
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  • 9
    Electronic Resource
    Electronic Resource
    Reassessment of the assignment of the InM2+3+VM2+ defect in CdTe and ternary II-VI compounds (1995)
    [S.l.] : American Institute of Physics (AIP)
    Journal of Applied Physics 78 (1995), S. 1776-1781 
    Details
    ISSN: 1089-7550
    Source: AIP Digital Archive
    Topics: Physics
    Notes: Previous perturbed angular correlation (PAC) spectroscopy measurements on the donor indium in CdTe and its alloys have revealed several defect complexes. One defect characterized by two sets of quadrupole interaction parameters, νQ=83 MHz, η=0.08 and νQ=92 MHz, η=0.08, was observed in Hg0.8Cd0.2Te (x=0.2 MCT) and attributed to the substitutional indium–metal vacancy complex InM2+3+VM2+. A defect characterized by νQ=61±1 MHz and asymmetry parameter η between 0 and 0.19 was seen in CdTe and widely attributed to the same complex. Both of these assignments were based mainly on an observed relationship between complex formation and the loss of metal ions. In this article we present PAC measurements on 111In-doped x=0.45 MCT (Hg0.55Cd0.45Te). These measurements reveal defects having quadrupole interactions very similar to those seen previously in CdTe and in x=0.2 MCT. Two unique defect fractions f1 and f2, characterized by νQ1=60±3 MHz, η1≈0–0.2, and νQ2=87±4 MHz, η2≈0–0.15, were seen in x=0.45 MCT, in some cases simultaneously. The observation of both of these interactions in the same material—if they correspond to the defects seen in CdTe and x=0.21 MCT—precludes the possibility that they both correspond to precisely the same defect. We also observed a change in the relative fractions of these two defects with time at room temperature; the fraction f2 vanished over a period of a day, while f1 and f0 (the fraction of indium atoms in sites having cubic or higher symmetry) increased. While we cannot rule out the possibility of a slow electronic transition, at present we favor a model in which one of the interactions (probably the one near 60 MHz) corresponds to a complex in which indium is paired to a fast-diffusing monovalent metal ion like Ag+, Cu+, or Li+. © 1995 American Institute of Physics.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1063/1.360207
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  • 10
    Electronic Resource
    Electronic Resource
    INTERFERON-INDUCER POLYRIBOINOSINIC- POLYRIBOCYTIDYLIC ACID: A POTENT ANTI-GASTRIC ULCER AGENT AND INHIBITOR OF THE GASTRIC PROTON PUMP IN RATS (1998)
    Oxford, UK : Blackwell Publishing Ltd
    Clinical and experimental pharmacology and physiology 25 (1998), S. 0 
    Details
    ISSN: 1440-1681
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: 1. Polyriboinosinic-polyribocytidylic acid (Poly I:Poly C), an interferon inducer was studied for its effect on gastric ulceration in rats. Polyriboinosinic-polyribocytidylic acid (1,2 and 4 mg/kg, i.m.) showed a dose-dependent inhibition of gastric ulcers induced by aspirin, cold restraint stress and pylorus ligation (Shay's model). Protective dose (PD50)±SEM values of Poly I:Poly C on these models of ulcers were 1.9±0.2, 2.3±0.4 and 2.8±0.4 (mg/kg, i.m.) respectively.2. Polyriboinosinic-polyribocytidylic acid (10-60 μg) produced dose-dependent inhibition of gastric proton pump (H+/K+-ATPase) activity in the gastric parietal microsomal fraction. The concentration of Poly I:Poly C causing a 50% inhibition (IC50)±SEM was found to be 17.6±1.2 μg.3. Polyriboinosinic-polyribocytidylic acid caused a significant decrease in free and total acid and pepsin and an increase in mucin content in Shay (pylorus-ligated) rat.4. Polyriboinosinic-polyribocytidylic acid did not exert a significant influence on isolated tissue preparations for anticholinergic (acetylcholine-induced contraction of guinea-pig ileum) and H2-anti-histaminic (histamine-induced contraction of rat uterus and guinea-pig auricle) activities.5. Thus, the present study indicates that Poly I:Poly C may possess anti-gastric ulcer activity as a result of inhibition of the gastric proton pump.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1111/j.1440-1681.1998.tb02252.x
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