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  • 1995-1999  (3)
  • equilibrium constant  (2)
  • Hematocrit  (1)
  • Solanum brevidens
  • 1
    Electronic Resource
    Electronic Resource
    Magnetite solubility and phase stability in alkaline media at elevated temperatures (1995)
    Springer
    Journal of solution chemistry 24 (1995), S. 837-877 
    Details
    ISSN: 1572-8927
    Keywords: Magnetite ; iron oxide ; ferrous and ferric ion hydrolysis ; phosphatocomplexing ; equilibrium constant ; pressurized water ; hydrothermal solutions ; corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A platinum-lined flowing autocláve facility was used to investigate the solubility behavior of magnetite (Fe3O4) in alkaline sodium phosphate and ammonium hydroxide solutions between 21 and 288°C. Measured iron solubilities were interpreted via a Fe(II)/Fe(III) ion hydroxo-, phosphato-, and ammino-complexing model and thermodynamic functions for these equilibria were obtained from a least-squares analysis of the data. A total of 14 iron ion species were fitted. Complexing equilibria are reported for 8 new species: Fe(OH)(HPO4)−, Fe(OH)2(HPO4)2−, Fe(OH)3(HPO4)2−, Fe(OH)(NH3)+, Fe(OH)2(PO4)3−, Fe(OH)4(HPO4)3−, Fe(OH)2(H2PO4)−, and Fe(OH)3(H2PO4)3−. At elevated temperatures, hydrolysis and phosphato complexing tended to stabilize Fe(III) relative to Fe(II), as evidenced by free energy changes fitted to the oxidation reactions. $$\begin{gathered} Fe(OH)_3^ - + H_2 O_ \leftarrow ^ \to Fe(OH)_4^ - + (1/2)H_2 (g) \hfill \\ Fe(OH)_2^{} (HPO_4 )^{2 - } + H_2 O_ \leftarrow ^ \to Fe(OH)_3 (HPO_4 )^{2 - } + (1/2)H_2 (g) \hfill \\ \end{gathered}$$ For temperatures below 83°C and for a dissolved hydrogen concentration of 234 μmol-kg−1, the activity of ferrous iron in aqueous solution is controlled by a hydrous Fe(II) oxide solid phase rather than magnetite.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00973442
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  • 2
    Electronic Resource
    Electronic Resource
    Solubility and Phase Behavior of Cr(III) Oxides in Alkaline Media at Elevated Temperatures (1998)
    Springer
    Journal of solution chemistry 27 (1998), S. 33-66 
    Details
    ISSN: 1572-8927
    Keywords: Chromium(III) oxide ; eskolaite ; chromium(III) oxide hydroxide ; chromium(III) hydroxide dehydration ; ferrous chromite ; aqueous solutions ; chromium(III) ion hydrolysis ; phosphatocomplexing ; equilibrium constant ; pressurized water ; hydrothermal solutions ; corrosion
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology
    Notes: Abstract A platinum-lined, flowing autoclave facility is used to investigate the solubility behavior of Cr2O3 and FeCr2O4 in alkaline sodium phosphate, sodium hydroxide, and ammonium hydroxide solutions between 21 and 288°C. Baseline Cr(III) ion solubilities were found to be on the order of 0.1 nmolal, which were enhanced by the formation of anionic hydroxo and phosphato complexes. At temperatures below 51°C, the activity of Cr(III) ions in aqueous solution is controlled by a Cr(OH)3·3H2O solid phase rather than Cr2O3; above 51°C the saturating solid phase is γ-CrOOH. Measured chromium solubilities were interpreted via a Cr(III) ion hydrolysis/complexing model and thermodynamic functions for the hydrolysis/complexing reaction equilibria were obtained from least-squares analyses of the data. The existence of four new Cr(III) ion complexes is reported: Cr(OH)3(H2PO4)−, Cr(OH)3(HPO4)2−, Cr(OH)3(PO4)3−, and Cr(OH)4(HPO4)-(H2PO4)4−. The last species is the dominant Cr(III) ion complex in concentrated, alkaline phosphate solutions at elevated temperatures.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1023/A:1022688528380
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  • 3
    Electronic Resource
    Electronic Resource
    An Analysis of Hypoxia in Sheep Brain using a Mathematical Model (1998)
    Springer
    Annals of biomedical engineering 26 (1998), S. 48-59 
    Details
    ISSN: 1573-9686
    Keywords: Oxygen transport ; Microcirculation ; Cerebral circulation ; Hypoxia ; Carbon monoxide ; Mathematical model ; Computer simulation ; Anemia ; Hematocrit ; Brain
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine , Technology
    Notes: Abstract Cerebral blood flow (CBF) increases as arterial oxygen content falls with hypoxic (low PO2), anemic (low hemoglobin) and carbon monoxide (CO) (high carboxyhemoglobin) hypoxia. Despite a higher arterial PO2, CO hypoxia provokes a greater increase in CBF than hypoxic hypoxia. We analyzed published data using a compartmental mathematical model to test the hypothesis that differences in PO2 in tissue, or a closely related vascular compartment, account for the greater response to CO hypoxia. Calculations showed that tissue, but not arteriolar, PO2 was lower in CO hypoxia because of the increased oxyhemoglobin affinity with CO hypoxia. Analysis of studies in which oxyhemoglobin affinity was changed independently of CO supports the conclusion that changes in tissue PO2 (or closely related capillary or venular PO2) are predictive of alterations in CBF. We then sought to determine the role of tissue PO2 in anemic hypoxia, with no change in arterial and little, if any, change in venous PO2. Calculations predict a small fall in tissue PO2 as hematocrit decreases from 55% to 20%. However, calculations show that changes in blood viscosity can account for the increase in CBF in anemic hypoxia over this range of hematocrits. © 1998 Biomedical Engineering Society. PAC98: 8710+e, 8722-q, 8745Ft
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1114/1.50
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