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  • Chemical Engineering  (8)
  • Biochemistry and Biotechnology  (5)
  • Pitzer model  (3)
  • Fe-Versorgung  (2)
  • 1
    ISSN: 1572-8927
    Keywords: Ion product of water ; carbonic acid ; dissociation constants ; NaClO4 solution ; iomic strength ; activity coefficients ; Pitzer model ; mixing parameters ; solution thermodynamics
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The ion product of water and the dissociation constants of carbonic acid have been determined in 0.1, 1.0, 3.0, and 5.0M NaClO4 at 25°C. The ion product of water K w ' has been evaluated by emf measurements with a combined glass electrode in NaClO4 solutions containing 0.001–0.1M HCLO4 or NaOH. The product K H ' K l ' K 2 ' of the Henry constant for CO2 and the dissociation constants for H2CO3 have been determined by titration of carbonate solutions equilibrated with pCO2 =10−3.52 atm, and K 2 ' has been evaluated by potentiometric titration and by measuring the H+ concentration at fixed HCO 3 − and CO 3 2- concentrations. The ion interaction (Pitzer) equations are applied to describe the constants K w ' , K 2 ' and K H ' H 1 ' K 2 ' as a function of the NaClO4 concentration. The experimental data are used to evaluate the mixing parametersΘ i/ClO 4 andΨ i/ClO 4 -/Na+ fori = OH -,HCO 3 - andCO 3 2-
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1572-8927
    Keywords: Sodium pertechnetate ; magnesium pertechnetate ; potassium pertechnetate ; osmotic coefficients ; activity coefficients ; solubility ; seawater system ; Pitzer model ; binary parameters ; mixing parameters
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract Isopiestic vapor pressure experiments are performed at 25°C with aqueous Mg(TcO4)2 solutions and with ternary mixtures containing various combinations of NaTcO4, Mg(TcO4)2, NaCl, MgCl2, Na2SO4, and MgSO4. The osmotic coefficients of the binary solutions are used to evaluate the binary Pitzer parameters β(0), β(1), and CΦ for Mg(TcO4)2. We previously reported these parameters for NaTcO4. The binary parameters for KTcO4 and Ca(TcO4)2 are evaluated from solubilities of KTcO4 in KCl and CaCl2 solutions, respectively. The mixing parameters Θ TcO 4 − /Cl −, ΨM/TcO 4 − /Cl −, Θ TcO 4 − /SO 4 2− , ΨM/TcO 4 − /SO 4 2− , and ΨNa + /Mg 2+ /TcO4 2− are calculated from either osmotic coefficients or solubilities in the corresponding ternary mixtures. The evaluated set of Pitzer parameters predicts well the activity coefficients and solubilities of KTcO4 in multicomponent systems.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1572-8927
    Keywords: Trivalent actinides ; curium ; americium ; solution thermodynamics ; carbonate complexation ; ionic strength ; Pitzer model ; concentrated solutions
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract The carbonate complexation reactions of Cm(III) were studied by time-resolved laser fluorescence spectroscopy in 0–6 m NaCl at 25°C. The ionic strength dependence of the stepwise formation constants for the carbonato complexes Cm(CO3) n 3−2n with n = 1, 2, 3, and 4 is described by modeling the activity coefficients of the Cm(III) species with Pitzer's ion-interaction approach. Based on the present results and literature data for Cm(III) and Am (III), the mean carbonate complexation constants at I = 0 are calculated to be: log β 101 o =8.1 ±0.3, log β 102 o =13.0 ± 0.6, log β 103 o =15.2 ± 0.4, and log β 104 o =13.0 ± 0.5. Combining these equilibrium constants at infinite dilution and the evaluated set of Pitzer parameters, a model is obtained, that reliably predicts the thermodynamics of bivalent actinide An(III) carbonate complexation in dilute to concentrated NaCl solution.
    Type of Medium: Electronic Resource
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  • 4
    ISSN: 1436-6215
    Keywords: Fe-Versorgung ; Proteinversorgung ; Fe-Protein-Wechselwirkung ; Fe-Konzentration in verschiedenen Organen
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary In a 2×3factorial experiment with growing rats the diet varied for the iron content (5, 25, 625 ppm) and for the protein content (5, 25, 45 %). The diets were fed ad libitum for 35 days. At the end of the experiment the iron content of different organs was determined. Both experimental factors and their interactions influenced the iron concentration as well as fresh weight and dry matter dependent on organ. Especially the influence of deficient protein supply and of insufficient iron supply was very marked. Dependent on the iron supply there are different responses between storage and functional compounds of iron.
    Notes: Zusammenfassung In einem 2×3faktoriellen Versuch mit wachsenden Ratten variierte der Fe-Gehalt der Diät in drei Stufen (5, 25, 625 ppm) und der Proteingehalt ebenfalls in drei Stufen (5, 25, 45 %). Die Diäten wurden den Versuchstieren 35 Tage ad libitum verfüttert und nach Versuchsende der Fe-Gehalt in verschiedenen Organen bestimmt. Die beiden Versuchsfaktoren und deren Wechselwirkungen beeinflußten die Fe-Konzentration sowie Frischgewicht und Trockensubstanzgehalt je nach Organ. Besonders starken Einfluß übten sowohl eine mangelhafte Proteinzufuhr als auch eine nicht bedarfsgerechte Fe-Versorgung aus. In Abhängigkeit von der Fe-Versorgung zeigten sich zwischen Speicherverbindungen und funktionellen Verbindungen für Eisen unterschiedliche Reaktionen.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Springer
    European journal of nutrition 23 (1984), S. 20-30 
    ISSN: 1436-6215
    Keywords: Cu-Versorgung ; Fe-Versorgung ; Cu-Fe-Wechselwirkungen ; Cu-Fe-Gehalte in Organen und Geweben
    Source: Springer Online Journal Archives 1860-2000
    Topics: Agriculture, Forestry, Horticulture, Fishery, Domestic Science, Nutrition , Medicine
    Description / Table of Contents: Summary The Fe and Cu contents in the femur and in the skeleton muscle were investigated in a trial series with factorial Fe and Cu supplies of growing rats (0, 25, 250, and 625 μg of Fe supply; 0, 10, 100, and 250 μg Cu supply per g of the diet). In addition, the reaction of the carcass to the different trace element supply was compared to the changes of the Fe and Cu contents in organs and tissues. In the femur, the Fe contents clearly increase in all grades of the Cu supply with increasing Fe supply. But because of the reduced live weight of the trial animals without Fe supply, this is valid only from 25 μg Fe/g diet on. For all Fe levels, the influence of the Cu supply on the concentration and the content of Cu results in a plateau in the range of 10–100 μg Cu/g diet; it is not reached with Cu deficiency and exceeded with an excessive Cu supply (250 μg/g). A clear increase of the Fe concentration in the muscle occurs only at a supply of 250 μg Fe/g diet. A further increase at 625 μg Fe/g only occurs at a Cu supply of 250 μg/g. Generally, the Fe concentration is reduced in the Cu deficiency. The Cu concentration in the muscle increases in all cases with the Cu supply, and the extent of this increase is strongly influenced by the Fe supply. The Fe contents in the carcass primarily depend on the Fe dosage. For the total contents of copper there are hints of a homeostatical regulation in the range of 10–100 μg Cu/g, but it seems to be disturbed if the Fe supply (0 or 25 μg/g) is insufficient. The comparison of the Fe and Cu contents in organs and tissues to those in the carcass shows that the reactions to the different supply levels, which are clearly different in the tissues, can be reproduced but insufficiently by the trace element analysis in the carcass.
    Notes: Zusammenfassung Im Rahmen einer Versuchsreihe mit faktorieller Fe- und Cu-Versorgung wachsender Ratten (0, 25, 250 und 625 μg Fe-Zulage; 0, 10, 100 und 250 μg Cu-Zulage je g Diät) wurden die Fe- und Cu-Gehalte im Femur und Skelettmuskel untersucht. Zusätzlich wurde die Reaktion des Ganzkörpers auf die unterschiedliche Spurenelementzufuhr mit der Veränderung des Fe- und Cu-Gehaltes in Organen und Geweben verglichen. Im Femur steigen die Gehalte an Eisen bei allen Stufen der Cu-Versorgung deutlich mit der Fe-Zufuhr an. Bedingt durch die verringerte Lebendmasse der Versuchstiere ohne Fe-Zulage gilt dieser Zusammenhang erst ab 25 μg Fe/g Diät. Der Einfluß der Cu-Versorgung auf die Konzentration und den Gehalt an Kupfer ergibt für alle Fe-Stufen ein Plateau im Bereich von 10–100 μg Cu/g Diät, das bei Cu-Mangel in der Regel unter-, bei exzessiver Cu-Zufuhr (250 μg/g) überschritten wird. Im Muskel erfolgt ein deutlicher Anstieg der Fe-Konzentration erst bei einer Zufuhr von 250 μg Fe/g Diät. Durch 625 μg Fe/g tritt nur bei einer Cu-Zulage von 250 μg/g eine weitere Erhöhung auf. Im Cu-Mangel ist die Fe-Konzentration in der Regel erniedrigt. Die Cu-Konzentration im Muskel steigt in allen Fällen mit der Cu-Zufuhr an, wobei das Ausmaß dieses Anstiegs stark durch die Fe-Versorgung beeinflußt wird. Die Fe-Gehalte im Ganzkörper sind in erster Linie von der Fe-Dosierung abhängig. Für die Gesamtgehalte an Kupfer ergeben sich im Bereich von 10–100 μg Cu/g Hinweise auf eine homöostatische Regulation, die aber bei unzureichender Fe-Zufuhr (0 bzw. 25 μg/g) offensichtlich gestört ist. Der Vergleich der Fe- und Cu-Gehalte in Organen und Geweben mit denen im Gesamtkörper zeigt, daß die in einzelnen Geweben deutlich unterschiedlichen Reaktionen auf die einzelnen Versorgungsstufen durch die Spurenelementbestimmung im Ganzkörper nur sehr begrenzt wiedergegeben werden.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1252-1257 
    ISSN: 0032-3888
    Keywords: Chemistry ; Chemical Engineering
    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: The mechanical properties of polyurethane-unsaturated polyester interpenetrating polymer networks (IPNs) that were prepared by reaction injection molding (RIM) process were measured with variations In composition, cross-link density, and relative reaction rate. From dynamic mechanical analysis (DMA), it was found that the two component polymers had a good compatibility over the whole composition range. The tensile strengths of the blends were greater than those of the pure components and had a maximum value at 50/50 composition. The modulus of elasticity and surface hardness decreased and the impact strength increased as the polyurethane content was increased, but the changes were not high at low polyurethane content, below 50%. For higher cross-link density, the compatibility was enhanced and the mechanical properties were improved. When the reaction rates of the components were different, some extent of phase separation was found in DMA and the properties were affected adversely.
    Additional Material: 7 Ill.
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  • 7
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 26 (1984), S. 12-16 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: For the purpose of improving ethanol productivity, the effect of air supplement on the performance of continuous ethanol fermentation system was studied. The effect of oxygen supplement on yeast concentration, cell yield, cell viability, extracellular ethanol concentration, ethanol yield, maintenance coefficient, specific rates of glucose assimilation, ethanol production, and ethanol productivity have been evaluated, using a high alcohol tolerant Saccharomyces cerevisiae STV89 strain and employing a continuous fermentor equipped with an accurate air metering system in the flow rate range 0-11 mL air/L/h. It was found that, when a small amount of oxygen up to about 80μ mol oxygen/L/h was supplied, the ethanol productivity was significantly enhanced as compared to the productivity of the culture without any air supplement. It was also found that the oxygen supplement improved cell viability considerably as well as the ethanol tolerance level of yeast. As the air supply rate was increased, from 0 to 11 mL air/L/h while maintaining a constant dilution rate at about 0.06 h-1, the cell concentration increased from 2.3 to 8.2 g/L and the ethanol productivity increased from 1.7 to 4.1 g ethanol/L/h, although the specific ethanol production rate decreased slightly from 0.75 to 0.5 g ethanol/g cell/h. The ethanol yield was slightly improved also with an increase in air supply rate, from about 0.37 to 0.45 ethanol/g glucose. The maintenance coefficient increased by only a small amount with the air supplement. This kind of air supplement technique may very well prove to be of practical importance to a development of a highly productive ethanol fermentation process system especially as a combined system with a high density cell culture technique.
    Additional Material: 9 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 31 (1988), S. 755-758 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 4 Ill.
    Type of Medium: Electronic Resource
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  • 9
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 28 (1986), S. 1838-1844 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: A carrier-supported mycelial growth of Penicillium chrysogenum was applied to penicillin fermentation system using celite as a support material. Hyphal growth through the pore matrices of the material showed strong anchorages and provided highly stable biofilm growth. With bioparticles developed in such a manner, both cell growth and penicillin production were observed to increase significantly compared to the conventional dispersed filamentous cultures. Maximum values of specific penicillin production rate were found to be constant regardless of the growth form. A three-phase fluidized-bed fermentor was designed and tested for penicillin production using the bioparticles. Two modes of operation, semicontinuous and repeated fed batch, of the fermentor were tried. It was noted that the overgrowth of free mycelia and the development of fluffy loose bioparticles caused poor mixing and made the fermentor operation quite difficult. Control of the bioparticle size and the extension of production phase were therefore considered important to maintain the reactor productivity at a desired level. From the results of repeated fed-batch operation it was found that the control of bioparticle size could be successfully achieved by phosphate-limiting culture condition. Penicillin production under this condition was also observed to be maintained at a high level (about 80% of the maximum) for at least 1 month.
    Additional Material: 7 Ill.
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  • 10
    Electronic Resource
    Electronic Resource
    New York, NY [u.a.] : Wiley-Blackwell
    Biotechnology and Bioengineering 34 (1989), S. 131-136 
    ISSN: 0006-3592
    Keywords: Chemistry ; Biochemistry and Biotechnology
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Biology , Process Engineering, Biotechnology, Nutrition Technology
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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