Interpretation of inert gas retention and excretion in the presence of stratified inhomogeneity

A computer model was developed to study the relationship between ventilation-to-perfusion (V/Q) mismatch and the development of inert gas arterial-to-alveolar partial pressure differences (a-A differences). Increasing inhomogeneity of V/Q ratio is revealed directly as an increase in the a-A difference of each gas. The quantitative relationships between the Q vs. V/Q distribution and the fractional a-A difference solubility plot (a-A difference plot) were studied and described. These studies demonstrated that for log normally distributed V/Q ratios, the area under the a-A difference plot is linearly related to the log variance of the V/Q distribution and can be estimated directly from the values obtained from six gases. The maximum a-A difference occurs for a gas whose solubility is numerically equal to the mean V/Q. The effects of departure from log normality and multimodality are discussed. We conclude from these studies that quantitative information regarding the degree of inhomogeneity of V/Q for log normal distribution is available from direct calculations of inert gas retention and excretion data. Qualitative information is also available indicating the departure from log normality and the region toward which the distribution is skewed.

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Can a/ distributions in the lung be recovered from inert gas retention data?

Respiration Physiology ◽

10.1016/0034-5687(75)90096-1 ◽

1975 ◽

Vol 25 (2) ◽

pp. 191-198 ◽

Cited By ~ 21

Author(s):

Albert J. Olszowka

Keyword(s):

Inert Gas ◽

Retention Data ◽

Inert Gas Retention

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Fission Gas Bubbles in Fractured UO2

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100101177 ◽

1968 ◽

Vol 26 ◽

pp. 286-287

Author(s):

O. M. Katz

Keyword(s):

Electron Microscopy ◽

Thermal Gradient ◽

Gas Bubbles ◽

Inert Gas ◽

Thermal Gradients ◽

Fission Gas ◽

Beam Heating ◽

Limited Application ◽

Bubble Characteristics ◽

Electron Beam Heating

The swelling of irradiated UO2 has been attributed to the migration and agglomeration of fission gas bubbles in a thermal gradient. High temperatures and thermal gradients obtained by electron beam heating simulate reactor behavior and lead to the postulation of swelling mechanisms. Although electron microscopy studies have been reported on UO2, two experimental procedures have limited application of the results: irradiation was achieved either with a stream of inert gas ions without fission or at depletions less than 2 x 1020 fissions/cm3 (∼3/4 at % burnup). This study was not limited either of these conditions and reports on the bubble characteristics observed by transmission and fractographic electron microscopy in high density (96% theoretical) UO2 irradiated between 3.5 and 31.3 x 1020 fissions/cm3 at temperatures below l600°F. Preliminary results from replicas of the as-polished and etched surfaces of these samples were published.

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