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Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

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45 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1975

Fluctuations in O2 stores and gas exchange with passive changes in posture

The purpose of the present study is to determine the effects of changes in posture on oxygen transfer at the mouth and pulmonary capillary membrane and to observe concomitant subtle changes in ventilation under specified assumptions. Breath-by-breath calculations are carried out with a box-balloon spirometer and mass spectrometer. Measurements are made before, during, and after passive tilt to 60 deg and on return to recumbency after 10 min erect. It is found that from supine to upright oxygen stores in the lung increases rapidly and oxygen stores in the blood drops slowly, creating a net deficit in oxygen transfer at the mouth of 130 ml in 10 min. Changes in oxygen stores in the blood result from shifts in blood volume and flow more than from changes in cardiac output. Refilling of oxygen stores in the blood is found to cause transient hypoxia with substantial hyperpnea.

Loeppky, J. A.↗
NASA NTRS1977

Specialized physiological studies in support of manned space flight

Breath-by-breath measurements of pulmonary capillary O2 transfer and ventilation with a box-balloon spirometer and mass spectrometer were made on 3 subjects before, during and after 10 min of lower body negative pressure (LBNP) at -20, -40 and -60 Torr with arterial samples at -60 Torr. Deficits in blood O2 stores (O2B) were noted during LBNP with repayment of O2B during recovery being related to the intensity of LBNP stress. Concurrent calf volume, measured with a Hg strain gauge, decreased towards baseline well before the peak rise in pulmonary capillary O2 transfer after the release of LBNP which signified that O2B changes were related to blood volume shifts. The return of O2-depleted pooled blood to the central circulation during the first min. of recovery caused significant stress-related hyperpnea which peaked near 30 sec. and returned to near baseline after the first min. Three-compartment lung model analyses indicated an increase in the ventilated unperfused lung fraction from 0.09 to 0.17 with the effective compartment decreasing from 0.83 to 0.77. It appears that the 30% increase in ventilation equivalent was primarily the result of less effective lung perfusion during the LBNP.

Source record↗
NASA NTRS1974

Determination of cardiac size from chest roentgenograms following Skylab missions

Decreased cardiothoracic transverse diameter ratios following Mercury, Gemini and Apollo space flights have been reported previously. To evaluate further changes in cardiac size, standard posteroanterior chest films in systole and diastole were obtained before flight and within a few hours after recovery on each of the Skylab astronauts. Postflight chest X-rays were visually compared to the preflight roentgenograms for possible changes in pulmonary vasculature, lung parenchyma, bony or soft tissue structures. From these roentgenograms the following measurements were obtained: cardiac and thoracic transverse diameters, cardiothoracic transverse diameter ratio, cardiac area from the product of both diagonal diameters, cardiac silhouette area by planimetry, thoracic cage area and cardiothoracic area ratio. The postflight frontal cardiac silhouette sizes were significantly decreased when compared with the respective preflight values (P0.05 or 0.01). The observed changes are thought to be related to postflight decrease in the intracardiac chamber volume.

Nicogossian, A. E.↗
NASA NTRS2008

Electrostatic Characterization of Lunar Dust

To ensure the safety and success of future lunar exploration missions, it is important to measure the toxicity of the lunar dust and its electrostatic properties. The electrostatic properties of lunar dust govern its behavior, from how the dust is deposited in an astronaut s lungs to how it contaminates equipment surfaces. NASA has identified the threat caused by lunar dust as one of the top two problems that need to be solved before returning to the Moon. To understand the electrostatic nature of lunar dust, NASA must answer the following questions: (1) how much charge can accumulate on the dust? (2) how long will the charge remain? and (3) can the dust be removed? These questions can be answered by measuring the electrostatic properties of the dust: its volume resistivity, charge decay, charge-to-mass ratio or chargeability, and dielectric properties.

Source record↗
NASA NTRS2001

Geostationary Imaging FTS (GIFTS) Data Processing: Measurement Simulation and Compression

GIFTS (Geostationary Imaging Fourier Transform Spectrometer), a forerunner of next generation geostationary satellite weather observing systems, will be built to fly on the NASA EO-3 geostationary orbit mission in 2004 to demonstrate the use of large area detector arrays and readouts. Timely high spatial resolution images and quantitative soundings of clouds, water vapor, temperature, and pollutants of the atmosphere for weather prediction and air quality monitoring will be achieved. GIFTS is novel in terms of providing many scientific returns that traditionally can only be achieved by separate advanced imaging and sounding systems. GIFTS' ability to obtain half-hourly high vertical density wind over the full earth disk is revolutionary. However, these new technologies bring forth many challenges for data transmission, archiving, and geophysical data processing. In this paper, we will focus on the aspect of data volume and downlink issues by conducting a GIFTS data compression experiment. We will discuss the scenario of using principal component analysis as a foundation for atmospheric data retrieval and compression of uncalibrated and un-normalized interferograms. The effects of compression on the degradation of the signal and noise reduction in interferogram and spectral domains will be highlighted. A simulation system developed to model the GIFTS instrument measurements is described in detail.

Huang, Hung-Lung↗
NASA NTRS1996

Cardiopulmonary Changes with Moderate Decompression in Rats

Sprague-Dawley rats were compressed to 616 kPa for 120 min then decompressed at 38 kPa/min to assess the cardiovascular and pulmonary responses to moderate decompression stress. In one series of experiments the rats were chronically instrumented with Doppler ultrasonic probes for simultaneous measurement of blood pressure, cardiac output, heart rate, left and right ventricular wall thickening fraction, and venous bubble detection. Data were collected at base-line, throughout the compression/decompression protocol, and for 120 min post decompression. In a second series of experiments the pulmonary responses to the decompression protocol were evaluated in non-instrumented rats. Analyses included blood gases, pleural and bronchoalveolar lavage (BAL) protein and hemoglobin concentration, pulmonary edema, BAL and lung tissue phospholipids, lung compliance, and cell counts. Venous bubbles were directly observed in 90% of the rats where immediate post-decompression autopsy was performed and in 37% using implanted Doppler monitors. Cardiac output, stroke volume, and right ventricular wall thickening fractions were significantly decreased post decompression, whereas systemic vascular resistance was increased suggesting a decrease in venous return. BAL Hb and total protein levels were increased 0 and 60 min post decompression, pleural and plasma levels were unchanged. BAL white blood cells and neutrophil percentages were increased 0 and 60 min post decompression and pulmonary edema was detected. Venous bubbles produced with moderate decompression profiles give detectable cardiovascular and pulmonary responses in the rat.

Robinson, R.↗
NASA NTRS1999

Validation of fluorescent-labeled microspheres for measurement of relative blood flow in severely injured lungs

The aim of the study was to validate a nonradioactive method for relative blood flow measurements in severely injured lungs that avoids labor-intensive tissue processing. The use of fluorescent-labeled microspheres was compared with the standard radiolabeled-microsphere method. In seven sheep, lung injury was established by using oleic acid. Five pairs of radio- and fluorescent-labeled microspheres were injected before and after established lung injury. Across all animals, 175 pieces were selected randomly. The radioactivity of each piece was determined by using a scintillation counter. The fluorescent dye was extracted from each piece with a solvent without digestion or filtering. The fluorescence was determined with an automated fluorescent spectrophotometer. Perfusion was calculated for each piece from both the radioactivity and fluorescence and volume normalized. Correlations between flow determined by the two methods were in the range from 0.987 +/- 0.007 (SD) to 0.991 +/- 0.002 (SD) after 9 days of soaking. Thus the fluorescent microsphere technique is a valuable tool for investigating regional perfusion in severely injured lungs and can replace radioactivity.

Non-NASA Center↗
NASA NTRS2003

Improved pulmonary function in working divers breathing nitrox at shallow depths

INTRODUCTION: There is limited data about the long-term pulmonary effects of nitrox use in divers at shallow depths. This study examined changes in pulmonary function in a cohort of working divers breathing a 46% oxygen enriched mixture while diving at depths less than 12 m. METHODS: A total of 43 working divers from the Neutral Buoyancy Laboratory (NBL), NASA-Johnson Space Center completed a questionnaire providing information on diving history prior to NBL employment, diving history outside the NBL since employment, and smoking history. Cumulative dive hours were obtained from the NBL dive-time database. Medical records were reviewed to obtain the diver's height, weight, and pulmonary function measurements from initial pre-dive, first year and third year annual medical examinations. RESULTS: The initial forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were greater than predicted, 104% and 102%, respectively. After 3 yr of diving at the NBL, both the FVC and FEV1 showed a significant (p < 0.01) increase of 6.3% and 5.5%, respectively. There were no significant changes in peak expiratory flow (PEF), forced mid-expiratory flow rate (FEF(25-75%)), and forced expiratory flow rates at 25%, 50%, and 75% of FVC expired (FEF25%, FEF50%, FEF75%). Cumulative NBL dive hours was the only contributing variable found to be significantly associated with both FVC and FEV1 at 1 and 3 yr. CONCLUSIONS: NBL divers initially belong to a select group with larger than predicted lung volumes. Regular diving with nitrox at shallow depths over a 3-yr period did not impair pulmonary function. Improvements in FVC and FEV1 were primarily due to a training effect.

Non-programmatic↗
NASA NTRS2002

Effect of 6 degrees head-down tilt on cardiopulmonary function: comparison with microgravity

BACKGROUND: Head-down tilt (HDT) of 6 degrees is a commonly used model of weightlessness, but there are few comparisons with actual microgravity. HYPOTHESIS: Our study was designed to prove that the changes in cardiopulmonary function seen in HDT would be similar to those seen in microgravity. METHODS: We compared measurements of cardiovascular and pulmonary function from three separate spaceflights of 14 to 17 d duration, with data collected during a 17-d period of HDT. RESULTS: HDT proved a good model of the cardiovascular response to microgravity, resulting in increases in cardiac output and stroke volume of a similar magnitude to those seen in microgravity, with a concomitant reduction in heart rate. By contrast, HDT was a poor model of the effects of microgravity on pulmonary ventilation and gas exchange. CONCLUSION: Pulmonary function in HDT approximated the changes seen in the 1-G supine posture, while in microgravity this was much closer to that seen in the 1-G upright position. The differences probably reflect the fact that changes in cardiovascular function result primarily from fluid shifts within the entire body, whereas changes in pulmonary ventilation are primarily a result of mechanical influences on the lung and chest and abdominal wall.

NASA Discipline Cardiopulmonary↗