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  • Chemical Engineering  (8)
  • Engineering  (5)
  • Fe-Versorgung  (2)
  • 1
    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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  • 2
    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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  • 3
    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.
    Type of Medium: Electronic Resource
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  • 4
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 29 (1983), S. 353-360 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Pressure drop for a gas-solids suspension flowing concurrently downward in a 13-mm inside-diameter tube was investigated using 329-micron spherical glass beads in air. The gas Reynolds number varied from 0 to 30,000 with solids-loading ratios of up to 20 at a gas Reynolds number of 10,000. The frictional pressure drop for downflow was found to be a weaker function of the solids-loading ratio than the upflow case using data reported in the literature. Empirical correlation of the two-phase friction factor, in terms of the gas Reynolds number and a dimensionless parameter, CDEPD/[(1 - Ep)dp], showed that at high solids loadings, particles tend to stabilize the suspension flow. The dimensionless parameter seems to be applicable to a universal pressure drop correlation for solids-fluid systems, but requires further investigation.
    Additional Material: 13 Ill.
    Type of Medium: Electronic Resource
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  • 5
    Electronic Resource
    Electronic Resource
    Hoboken, NJ : Wiley-Blackwell
    AIChE Journal 29 (1983), S. 306-312 
    ISSN: 0001-1541
    Keywords: Chemistry ; Chemical Engineering
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology , Process Engineering, Biotechnology, Nutrition Technology
    Notes: Heat transfer to a gas-solids suspension flowing cocurrently downward in a 13-mm inside diameter tube with uniform heat-flux boundary conditions was investigated using 329-μm spherical glass beads in air. The gas Reynolds number varied from 0 to 30,000 with solids-loading ratios of up to 20 at a gas Reynolds number of 10,000. The suspension Nusselt number, defined in terms of the wall-to-gas mixed-mean temperature difference, decreased with increasing solids-loading ratio at high Reynolds numbers, while it changed little from the value for gas alone at low Reynolds numbers. A possible explanation is given by considering the effects of particles on the fluid mechanical properties of the gas. Asymptotic Nusselt numbers in downflow are compared with results of other investigations for upflow.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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  • 6
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 29 (1989), S. 581-585 
    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: Poly(vinyl chloride), PVC, is shown to be miscible with an α-methyl styrene/acrylonitrile copolymer, αMSAN, containing 30 percent AN by weight using differential scanning calorimetry for blends prepared by several methods. Melt blending gave single Tg mixtures; whereas, solution techniques gave results that depended on the solvent choice and the manner in which it was removed. These blends do not phase separate on heating prior to significant PVC decomposition (∼250°C) in contrast to PVC/SAN blends which have much lower cloud points. Repulsion between α-methyl styrene and acrylonitrile units in the copolymer is the principal cause for miscibility of this system as shown by an analysis based on a binary interaction model using calorimetry data for low molecular weight liquid analog compounds.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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  • 7
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 33 (1993), S. 1452-1457 
    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: A high-temperature radical scavenger, 2,2-diphenyl-l-picryl hydrazyl (DPPH), has been used to study the reaction mechanisms of polyacrylonitrile (PAN) on thermal treatment. The effect of DPPH on the cyclization reaction of PAN in both air and nitrogen, investigated by differential scanning calorimetry (DSC), helped to verify the proposed reaction mechanisms, i.e., the free radical and the ionic ones. For PAN homopolymer, the peak temperature of the reaction exotherm shifted to higher temperatures and the heat of reaction was decreased with increasing DPPH concentration. For PAN copolymer with methylacrylate and itaconic acid, however, the effects of DPPH on DSC thermograms were insignificant. The effects of IPPH suggest that the reaction of the nitrile groups proceeds by free radicals for the homopolymer while by ions for the copolymer. The activation energies for the thermal reactions of PAN in both air and nitrogen were also estimated by the dynamic DSC method, and they proved to be highly dependent on reaction mechanism, environment of thermal treatment, and DPPH concentration.
    Additional Material: 7 Ill.
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  • 8
    Electronic Resource
    Electronic Resource
    Chichester : Wiley-Blackwell
    Communications in Numerical Methods in Engineering 13 (1997), S. 565-572 
    ISSN: 1069-8299
    Keywords: mixed harmonic element ; shells of revolution ; consistent stress parameters ; Engineering ; Numerical Methods and Modeling
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: A simple and efficient three-noded mixed harmonic axisymmetric element for shells of revolution under non-symmetric loading is developed. The present element considering shear strain is based on a modified mixed variational principle in which the independent unknowns are only the quantities prescribable at the shell edges. The non-symmetric variations of the displacements and stress resultants in the circumferential direction are decomposed in terms of Fourier series. The stress resultants are eliminated on the element level so that the standard stiffness equations are obtained. The importance of consistent stress parameters is addressed and the efficiency of the present consistent mixed element is shown. © 1997 John Wiley & Sons, Ltd.
    Additional Material: 5 Ill.
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  • 9
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 27 (1987), S. 1243-1251 
    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: A computer simulation model was developed to analyze the reaction injection molding (RIM) process of polyurethane and unsaturated polyester blends. The reaction kinetics and viscosity functions of each component were obtained through actual experiments, and a mathematical scheme for numerical calculation was set up in cylindrical coordinates to predict the temperature and conversion profiles within a disc-type mold. The temperature change calculated from the simulation was compared with the temperature rise measured in actual RIM experiments. The effects of the feed temperature, wall temperature, and catalyst levels on the maximum exothermic temperature and the demolding time were evaluated in a search for the optimum processing conditions.
    Additional Material: 14 Ill.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Stamford, Conn. [u.a.] : Wiley-Blackwell
    Polymer Engineering and Science 31 (1991), S. 981-987 
    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 effects of phase separation temperature and time on the tensile, dynamic mechanical, and tear properties of blends of polystyrene and poly(vinyl methyl ether) were investigated after phase separation above their respective cloud points with specified temperature-annealing time protocols. The results are analyzed in terms of the phase connectivity, interfacial adhesion, and changes in the glass transition temperature.
    Additional Material: 12 Ill.
    Type of Medium: Electronic Resource
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