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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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At least 37 records · Page 2
All sourcesNASA NTRSDOE OSTI
NASA NTRS1961

Carbon Dioxide Reduction Systems

The Methoxy system for regenerating oxygen from carbon dioxide was studied. Experiments indicate that the reaction between carbon dioxide and hydrogen can be carried out with ease in an efficient manner and with excellent heat conservation. A small reactor capable of handling the C02 expired by three men has been built and operated. The decomposition of methane by therma1,arc and catalytic processes was studied. Both the arc and catalytic processes gave encouraging results with over 90 percent of the methane being decomposed to carbon and hydrogen in some of the catalytic processes. Control of the carbon deposition in both the catalytic and arc processes is of great importance to prevent catalyst deactivation and short circuiting of electrical equipment. Sensitive analytical techniques have been developed for all of the components present in the reactor effluent streams.

METHOXY SYSTEM↗
NASA NTRS1971

Metabolic effects of artificial environments

The mechanisms by which inert gases influence metabolism were investigated from several viewpoints. Groups of rats were exposed at the thermal neutral temperature of the respective mixtures, to normoxic (P sub A 02 = 100 mm Hq) environments with argon, helium or nitrogen as the diluent at a total pressure of one atmosphere. The possible influence of diluent gases on oxygen transport to the cell was examined with hypoxic (P sub A O2 = 70 mm Hg) mixtures of the same diluent gases. Metabolic measurements included food, water, and oxygen consumption, CO2 production, hematocrit and the rate C-14O2 of expiration subsequent to intraperitoneal injection of acetate-1-C-14 or glucose UL-C-14. Argon-exposed animals showed a consistently decreased metabolic rate while, on the other hand, helium-exposed rats did not significantly alter metabolic rate relative to nitrogen. Certain indices, including acetate and glucose utilization, suggested that helium attenuated the imposed hypoxia at the cellular level while argon facilitated it as compared with nitrogen. These results suggest that metabolic influence of helium is largely thermal in nature while argon has a significant direct metabolic effect and that diluent gases may selectively influence oxygen availability to the interior of the cell.

Jordan, J. P.↗
NASA NTRS1972

Operation and testing of Mark 10 Mod 3 underwater breathing apparatus

Performance tests on a closed circuit, mixed gas underwater breathing apparatus are reported. The equipment is designed to provide a minimum diving duration of four hours at 1500 ft below sea surface; it senses oxygen partial pressure in the breathing gas mix and controls oxygen content of the breathing gas within narrow limits about a preset value. The breathing circuit subsystem provides respirable gas to the diver and removes carbon dioxide and moisture from the expired gas. Test results indicate undesirable variations in oxygen partial pressure with oxygen addition and insufficient carbon dioxide absorption.

Milwee, W. I., Jr.↗
NASA NTRS1972

Rare-gas effects on metabolism and inert gas narcosis

The detailed examination is reported of the theory that narcosis results from expansion of the cell membrane under high partial pressures. The research is partially based on the hypothesis that, like oxygen toxicity, the mechanism of metabolic effects of rare gases may be similar at both low and high pressures and are simply more observable at high pressures. Using adult female goats, the parameters measured include oxygen consumption, CO2 production, respiration rate, heart rate, rectal and skin temperatures and the analysis of electroencephalograms and evoked response. Additionally, the specific activity is measured of plasma glucose subsequent to injection of glucose-UL-C-14, intravenous infusion, specific activity of expired CO2, unesterified fatty acid levels and whole blood lactate-to-pyruvate ratios. Also studied were the effects of acetylsalicylic acid, vitamin E and cationic detergents (which alleviate narcosis) upon metabolic changes induced by high pressure narcosis.

Source record↗
NASA NTRS1972

Respiratory weight losses during exercise.

Evaporative water loss from the respiratory tract was determined over a wide range of exercise. The absolute humidity of the expired air was the same at all levels of exercise and equal to that measured at rest. The rate of respiratory water loss during exercise was found to be 0.019 of the oxygen uptake times (44 minus water vapor pressure). The rate of weight loss during exercise due to CO2-O2 exchange was calculated. For exercise at oxygen consumption rates exceeding 1.5 L/min in a dry environment with a water vapor pressure of 10 mm Hg, the total rate of weight loss via the respiratory tract is on the order of 2-5 g/min.

Mitchell, J. W.↗
NASA NTRS1972

Life support system definition for a low cost shuttle launched space station.

Discussion of the tradeoffs and EC/LS definition for a low cost shuttle launched space station to be launched in the late 1970s for use as a long-term manned scientific laboratory. The space station consists of 14-ft-diam modules, clustered together to support a six-man crew at the initial space station (ISS) level and a 12-man crew at the growth space station (GSS) level. Key design guidelines specify low initial cost and low total program cost and require two separate pressurized habitable compartments with independent lift support capability. The methodology used to select the EC/LS design consisted of systematically reducing quantitative parameters to a common denominator of cost. This approach eliminates many of the inconsistencies that can occur in such decision making. The EC/LS system selected is a partially closed system which recovers urine, condensate, and wash water and concentrates crew expired CO2 for use in a low thrust resistojet propulsion system.

Nelson, W. G.↗
NASA NTRS1973

Computer system for monitoring radiorepirometry data

System monitors expired breath patterns simultaneously from four small animals after they have been injected with carbon-14 substrates. It has revealed significant quantitative differences in oxidation patterns of glucose following such mild treatments of rats as a change in diet or environment.

Feller, D. D.↗
NASA NTRS1973

Further development and testing of the metabolic gas analyzer

Continued development of a metabolic monitor utilizing a mass spectrometer and digital computer to perform measurements and data reduction, is reported. The device prints-out breath-by-breath values for 02 consumption, C02 production, minute volume and tidal volume. The flow is measured by introduction of a tracer gas to the expired gas stream. Design modifications to reduce pressure drop in the flow splitter to one inch of water at 600 liters/min flow and to extend the range of linear flow measurement to 1000 liters/min are discussed.

Source record↗
NASA NTRS1973

Respiratory analysis system and method

A system is described for monitoring the respiratory process in which the gas flow rate and the frequency of respiration and expiration cycles can be determined on a real time basis. A face mask is provided with one-way inlet and outlet valves where the gas flow is through independent flowmeters and through a mass spectrometer. The opening and closing of a valve operates an electrical switch, and the combination of the two switches produces a low frequency electrical signal of the respiratory inhalation and exhalation cycles. During the time a switch is operated, the corresponsing flowmeter produces electric pulses representative of the flow rate; the electrical pulses being at a higher frequency than that of the breathing cycle and combined with the low frequency signal. The high frequency pulses are supplied to conventional analyzer computer which also receives temperature and pressure inputs and computes mass flow rate and totalized mass flow of gas. From the mass spectrometer, components of the gas are separately computed as to flow rate. The electrical switches cause operation of up-down inputs of a reversible counter. The respective up and down cycles can be individually monitored and combined for various respiratory measurements.

Liu, F. F.↗
NASA NTRS1973

Metabolic activity, experiment M171

The Skylab metabolic activity experiment determines if man's metabolic effectiveness in doing mechanical work is progressively altered by a simulated Skylab environment, including environmental factors such as slightly increased pCO2. This test identified several hardware/procedural anomalies. The most important of these were: (1) the metabolic analyzer measured carbon dioxide production and expired water too high; (2) the ergometer load module failed under continuous high workload conditions; (3) a higher than desirable number of erroneous blood pressure measurements were recorded; (4) vital capacity measurements were unreliable; and (5) anticipated crew personal exercise needs to be more structured.

Michel, E. L.↗
NASA NTRS1974

Effects of N2O narcosis on the contraction and repayment of an oxygen debt

The oxygen deficit, oxygen debt, and the difference between them were measured in five male and three female subjects during and after exercise while breathing either air or a normoxic mixture containing 33% N2O and nitrogen. With the exception of a higher respiratory quotient at rest in N2O, there were no statistically significant differences for oxygen consumption, carbon dioxide production, expired gas volume, heart rate or blood lactate while breathing N2O during rest, exercise, or recovery. An appreciably, but not statistically, greater mean oxygen deficit was found in N2O along with a significantly greater mean oxygen debt; deficit-debt difference was unaffected by N2O. It was speculated that N2O narcosis did not affect the ability to utilize oxygen but that the response to the greater oxygen need of exercise may have been slowed with perhaps a concomitant greater depletion of stored high energy compounds.

Schatte, C. L.↗
NASA NTRS1974

Toxicity of the pyrolysis products of spacecraft materials

A number of spacecraft construction materials are evaluated for the toxic effects of their thermodegradation products on rats. Pyrolysis toxicity testing of pyrolysate fumes establish carbon monoxide, carbon dioxide and hydrogen cyanide as the most common intoxicating agents. Generally, COHb levels of animals expiring in the test chamber suggest higher concentrations of CO are produced with larger samples of most materials.

Lawrence, W. H.↗
NASA NTRS1975

Total body nitrogen analysis

Studies of two potential in vivo neutron activation methods for determining total and partial body nitrogen in animals and humans are described. A method using the CO-11 in the expired air as a measure of nitrogen content was found to be adequate for small animals such as rats, but inadequate for human measurements due to a slow excretion rate. Studies on the method of measuring the induced N-13 in the body show that with further development, this method should be adequate for measuring muscle mass changes occurring in animals or humans during space flight.

Palmer, H. E.↗
NASA NTRS1978

Continuous distributions of specific ventilation recovered from inert gas washout

A new technique is described for recovering continuous distributions of ventilation as a function of tidal ventilation/volume ratio from the nitrogen washout. The analysis yields a continuous distribution of ventilation as a function of tidal ventilation/volume ratio represented as fractional ventilations of 50 compartments plus dead space. The procedure was verified by recovering known distributions from data to which noise had been added. Using an apparatus to control the subject's tidal volume and FRC, mixed expired N2 data gave the following results: (a) the distributions of young, normal subjects were narrow and unimodal; (b) those of subjects over age 40 were broader with more poorly ventilated units; (c) patients with pulmonary disease of all descriptions showed enlarged dead space; (d) patients with cystic fibrosis showed multimodal distributions with the bulk of the ventilation going to overventilated units; and (e) patients with obstructive lung disease fell into several classes, three of which are illustrated.

Lewis, S. M.↗
NASA NTRS1978

Emptying patterns of the lung studied by multiple-breath N2 washout

Changes in the nitrogen concentration seen during the single-breath nitrogen washout reflect changes in relative flow (ventilation) from units with differing ventilation/volume ratios. The multiple-breath washout provides sufficient data on ventilation for units with varying ventilation/volume ratios to be plotted as a function of the volume expired. Flow from the dead space may also be determined. In young normals the emptying patterns are narrow and unimodal throughout the alveolar plateau with little or no flow from the dead space at the end of the breath. Older normals show more flow from the dead space, particularly toward the end of the breath, and some show a high ventilation/volume ratio mode early in the breath. Patients with obstructive lung disease have a high flow from the dead space which is present throughout the breath. A well ventilated mode at the end of the breath is seen in some obstructed subjects. Patients with cystic fibrosis showed a poorly ventilated mode appearing at the end of the breath as well as a very high dead space.

Lewis, S. M.↗
NASA NTRS1979

Computer program for calculation of oxygen uptake

A description and operational precedures are presented for a computer program, written in Super Basic, that calculates oxygen uptake, carbon dioxide production, and related ventilation parameters. Program features include: (1) the option of entering slope and intercept values of calibration curves for the O2 and CO2 and analyzers; (2) calculation of expired water vapor pressure; and (3) the option of entering inspured O2 and CO2 concentrations. The program is easily adaptable for programmable laboratory calculators.

Castle, B. L.↗
NASA NTRS1978

Monitoring the state of the human airways by analysis of respiratory sound

A mechanism whereby sound is generated by the motion of vortices in the human lung is described. This mechanism is believed to be responsible for most of the sound which is generated both on inspiration and expiration in normal lungs. Mathematical expressions for the frequencies of sound generated, which depend only upon the axial flow velocity and diameters of the bronchi, are derived. This theory allows the location within the bronchial tree from which particular sounds emanate to be determined. Redistribution of pulmonary blood volume following transition from earth gravity to the weightless state probably alters the caliber of certain airways and doubtless alters sound transmission properties of the lung. We believe that these changes can be monitored effectively and non-invasively by spectral analysis of pulmonary sound.

Hardin, J. C.↗