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  • Engineering  (5)
  • Pitzer model  (3)
  • thermal diffusivity  (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
    Springer
    International journal of thermophysics 17 (1996), S. 695-703 
    ISSN: 1572-9567
    Keywords: AC calorimetry ; CVD diamond film ; Debye phonon model ; grain boundary ; thermal conductivity ; thermal diffusivity ; U-process
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Diamond films 60 and 170 µm in thickness were grown by PACVD (plasma-assisted chemical vapor deposition) under similar conditions. The thermal diffusivity of these freestanding films was measured between 100 and 300 K using AC calorimetry. Radiation heat loss from the surface was estimated by analyzing both the amplitude and the phase shift of a lock-in amplifier signal. Thermal conductivity was calculated using the specific heat data of natural diamond. At room temperature, the thermal conductivity of the 60 and 170 υm films is 9 and 16 W-cm−1. K−1 respectively, which is 40–70% that of natural diamond, The temperature dependence of thermal conductivity of the CVD diamond films is similar to that of natural diamond, Phonon scattering processes are considered using the Debye model, The microsize of the grain boundary has a significant effect on the mean free path of phonons at low temperatures. The grain in CVD diamond film is grown as a columnar structure, Thus, the thicker film has the larger mean grain size and the higher thermal conductivity. Scanning electron microscopy (SEM) and Raman spectroscopy were used to study the microstructure of the CVD diamond films. In this experiment, we evaluated the quality of CVD diamond film of the whole sample by measuring the thermal conductivity.
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  • 7
    Electronic Resource
    Electronic Resource
    Springer
    International journal of thermophysics 19 (1998), S. 281-290 
    ISSN: 1572-9567
    Keywords: GaAs ; impurities ; phonons ; photothermal displacement technique ; semiconductors ; Si ; thermal conductivity ; thermal diffusivity
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract Thermal conductivity and thermal diffusivity of Si and GaAs wafers were measured using the photothermal displacement technique, and the temperature dependence of these two quantities was investigated. Thermal diffusivity was obtained from the phase difference between the heating source and the signal, and thermal conductivity was determined from the maximum value of the signal amplitude in the temperature range 80 to 300 K. It was verified that an increase in doping concentration gives rise to a decrease in thermal conductivity at low temperatures. The experimental results obtained on samples with different types and doping concentrations are consistent with those expected from theoretical considerations.
    Type of Medium: Electronic Resource
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  • 8
    ISSN: 1572-9567
    Keywords: antireflection coating ; parameter estimation ; photoacoustic effect ; thermal diffusivity ; through-plane
    Source: Springer Online Journal Archives 1860-2000
    Topics: Physics
    Notes: Abstract In this study, we designed and developed two-layer antireflection (AR) optical coating samples on glass substrates, using different evaporation conditions of coating rates and substrate temperatures for two dielectric materials, MgF2 and ZnS, with different refractive indices. The through-plane thermal diffusivity of these systems was measured using the photoacoustic effect. The optical thicknesses of MgF2 and ZnS layers were fixed at 5λ/4 (λ=514.5 nm) and λ, respectively, and the thermal diffusivities of the samples were obtained from the measured amplitude of the photoacoustic signals by changing the chopping frequency of the Ar+ laser beam. The results demonstrated that the thermal diffusivity of the sample fabricated under the conditions of 10μÅ·s−1 and 150°C had the maximum value and that the results were directly related to the microstructure of the film system.
    Type of Medium: Electronic Resource
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  • 9
    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.
    Type of Medium: Electronic Resource
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  • 10
    Electronic Resource
    Electronic Resource
    Chichester [u.a.] : Wiley-Blackwell
    International Journal for Numerical Methods in Engineering 39 (1996), S. 1903-1914 
    ISSN: 0029-5981
    Keywords: axisymmetric shell ; mixed finite element ; Engineering ; Engineering General
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Mathematics , Technology
    Notes: An efficient, perhaps simplest, three-noded mixed finite element is proposed for axisymmetric shell analysis. The key feature in the present formulation is to start with a better variational principle in which the independent unknowns are only the quantities that can be prescribed at the shell edges. If the consistency for field approximations is satisfied, no other numerical consideration is necessary in the present element. Several examples confirm the satisfactory numerical behaviour of the present mixed element.
    Additional Material: 7 Ill.
    Type of Medium: Electronic Resource
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