Capillary oxygen concentration

The predicted partial pressure in the capillary can be computed by inverting Equation (8.14) to convert from total oxygen to partial pressure. The oxygen profile in the tissue as a function of r and z is given by combining Equation (8.19), which gives the capillary oxygen concentration as a function of z, with Equation (8.11),... 

Since the consumption of oxygen by the fetus is not considered in this study, a maternal blood velocity change to a zero velocity would result in a fetal end capillary oxygen concentration that is equal to the... 

Examination of the curves of Figure 21 shows that as the magnitude of the period of oscillation of the velocity function decreases (from 45 sec to 15 sec), the minimum fetal blood end capillary oxygen concentration increases from 26.3 mm Hg for a period of 45 sec to 27.8 mm Hg for a period of 15 sec. Additionally, the maximum fetal oxygen concentration decreases from 30 mm Hg (the normal value) for the 45-sec period to 28.6 mm Hg for the period of 15 sec. Thus, longer periods of contrac-... 

Unsteady-State Analysis Including Axial Dispersion. As in the previous unsteady-state analysis, the effects of placental barrier tissue oxygen consumption are neglected in this study. For the unsteady-state analysis of the model in which axial dispersion was included, one study was conducted. This study involved placing a step change on the maternal blood velocity to a new maternal blood velocity of 0.125 times the normal in an attempt to determine the effects of axial dispersion on the system at low maternal blood velocities. The discussion of this study is divided into the following two parts first, the effect of axial dispersion on the response of the fetal blood end capillary oxygen concentration, and second, the effect on the transient axial profiles. 

Figure 3.29 (a) Oxygen concentration profile at the inlet and outlet of the compartments of the high-throughput micro reactor. The inlets of the sampling tubes have to penetrate into the compartments to minimize flow cross-over, (b) Area averaged oxygen concentration at one capillary outlet. Total flow velocity 50 (1), 75 (2) and 100 cm3 min-1 (3) [55] (by courtesy of ACS). 

In the fetal capillary it is not so easy to predict what the effects of axial dispersion will be. The direction of axial diffusion in the fetal channel is opposite to the direction of flow, namely from the exit of the channel toward the entrance. This should have the effect of reducing the oxygen concentration of fetal blood at the fetal capillary exit. Axial diffusion, if any, in the maternal channel, however, should increase the concentration of oxygen leaving the maternal channel. This would result in an increased radial oxygen concentration gradient between maternal and fetal blood at the exit of the system which would act to increase... 

Oxygen concentration is continuous at the capillary-tissue interface, and transport across the interface can be described by Fick s first law. 

Equations 5 and 12 are two coupled nonlinear differential equations that completely describe the oxygen concentration in the three-dimensional model, provided that the influence of the capillary membrane as a diffusion barrier can be neglected. 

Polymerization of the hemoglobin molecules is highly dependent on the concentration of HbS and is promoted by the conformation of the deoxygenated molecules. At 100% oxygen saturation, even high concentrations of HbS will not polymerize. A red blood cell spends the longest amount of time at the lower oxygen concentrations of the venous capillary bed, where polymerization is most likely initiated. 

There is a rich literature associated with studies of the breakdown or formation of specific chemical compounds and classes of chemical componnds during burning processes. A study of the thermal decomposition of pentachlorobenzene, hexachlo-robenzene, and octachlorostyrene in air contained many such citations. In this study, nearly pure 10- to 20-mg samples of the cited chemicals were decomposed in a vertical combustion furnace and the decomposition product trapped on cooled X AD-4 resin followed by charcoal tubes. The adsorbed components were desorbed with toluene and analyzed using capillary GC and GC/MS. The decomposition products formed depended upon the applied temperature, the oxygen concentration, and the residence time in the hot zone of the combustion chamber. 

Loss of molecular oxygen in closed capillaries containing liposomes has been used as a diagnostic indicator of lipid peroxidation (13-17). The oximetry method was developed for measuring the oxygen concentrations during lipid peroxidation (12,17). 

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