Rapid compressions in a captive bubble apparatus are isothermal

Research output: Contribution to journalArticle

Abstract

Captive bubbles are commonly used to determine how interfacial films of pulmonary surfactant respond to changes in surface area, achieved by varying hydrostatic pressure. Although assumed to be isothermal, the gas phase temperature (Tg) would increase by >100°C during compression from 1 to 3 atm if the process were adiabatic. To determine the actual change in temperature, we monitored pressure (P) and volume (V) during compressions lasting g. P·V fell during and after the rapid compressions, consistent with reductions in n, the moles of gas phase molecules, because of increasing solubility in the subphase at higher P. As expected for a process with first-order kinetics, during 1 h after the rapid compression P·V decreased along a simple exponential curve. The temporal variation of n moles of gas was determined from P·V > 10 min after the compression when the two phases should be isothermal. Back extrapolation of n then allowed calculation of Tg from P·V immediately after the compression. Our results indicate that for bubbles with or without interfacial films compressed to >3 atm, within 1 s, the change in Tg is

Original languageEnglish (US)
Pages (from-to)1896-1900
Number of pages5
JournalJournal of Applied Physiology
Volume95
Issue number5
StatePublished - Nov 2003

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Gases
Pulmonary Surfactants
Hydrostatic Pressure
Temperature
Solubility
Pressure

Keywords

  • Adiabatic
  • Lung
  • Pulmonary surfactant
  • Surfactometer

ASJC Scopus subject areas

  • Physiology
  • Endocrinology
  • Orthopedics and Sports Medicine
  • Physical Therapy, Sports Therapy and Rehabilitation

Cite this

Rapid compressions in a captive bubble apparatus are isothermal. / Yan, Wenfei; Hall, Stephen (Steve).

In: Journal of Applied Physiology, Vol. 95, No. 5, 11.2003, p. 1896-1900.

Research output: Contribution to journalArticle

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