scholarly journals Human physiology under high pressure: I. Effects of Nitrogen, Carbon dioxide, and Cold

1941 ◽  
Vol 41 (3) ◽  
pp. 225-249 ◽  
Author(s):  
E. M. Case ◽  
J. B. S. Haldane
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Partial Pressure ◽  
Atmospheric Pressure ◽  
Good Deal ◽  
Considerable Effect ◽  
Manual Dexterity ◽  
Human Beings ◽  
Partial Pressures ◽  
Rapid Decompression

We confirm the finding of Behnke,et al.(1935) that air at 8·6 atm. pressure has a somewhat intoxicating effect on human beings, and that this effect is due to nitrogen. The nitrogen effect reaches its maximum after about 3 min. There was no reduction of manual dexterity in the test used by us, but a considerable effect on performance of arithmetic, and on most practical activities. At 10 atm. these effects were somewhat enhanced, and manual dexterity was lowered in some cases. When helium or hydrogen was substituted for nitrogen there was no intoxication.3–4% of carbon dioxide at atmospheric pressure caused no deterioration in manual or arithmetical skill, and in the two subjects tested, 6% of carbon dioxide caused no deterioration.When air containing about 0·4% of carbon dioxide, and therefore with a partial pressure of about 4%, was breathed at 10 atm., there was a marked deterioration in manual dexterity, and a good deal of confusion. When breathing carbon dioxide at partial pressures of 6·6–9·7% at 10. atm., eight subjects lost consciousness in 1–5 min., but some could tolerate partial pressures of over 8% for 5 min. or more. With half an hour's exposure to a partial pressure of 6–7% of carbon dioxide, one subject lost consciousness after 7 min. at 10 atm. pressure, and another nearly did so.We consider that the percentage of carbon dioxide in air at 10 atm. pressure should be kept below 0·3%. Exposure to high partial pressures of carbon dioxide at 10 atm. does not increase the liability to ‘bends’ or other symptoms due to rapid decompression.Immersion in water below 40° F. did not enhance the effects of high-pressure air, or of carbon dioxide at atmospheric pressure, but somewhat enhanced those of high pressure and carbon dioxide together.In certain breathing apparatus the resistance became so great at 10 atm. as to be intolerable.Few subjects experienced serious trouble during compression, or during or after decompression. But one developed a unilateral pneumothorax.

Gas Exchange

2017 ◽  
Author(s):  
John W. Kreit
Keyword(s):  
Carbon Dioxide ◽  
Gas Exchange ◽  
Partial Pressure ◽  
Capillary Blood ◽  
Pressure Gradients ◽  
Arterial Blood ◽  
Pulmonary Capillary ◽  
Partial Pressures ◽  
Pulmonary Capillary Blood ◽  
And Diffusion

Gas Exchange explains how four processes—delivery of oxygen, excretion of carbon dioxide, matching of ventilation and perfusion, and diffusion—allow the respiratory system to maintain normal partial pressures of oxygen (PaO2) and carbon dioxide (PaCO2) in the arterial blood. Partial pressure is important because O2 and CO2 molecules diffuse between alveolar gas and pulmonary capillary blood and between systemic capillary blood and the tissues along their partial pressure gradients, and diffusion continues until the partial pressures are equal. Ventilation is an essential part of gas exchange because it delivers O2, eliminates CO2, and determines ventilation–perfusion ratios. This chapter also explains how and why abnormalities in each of these processes may reduce PaO2, increase PaCO2, or both.

The Ventilatory Response to Hypoxia Below the Carbon Dioxide Threshold

1997 ◽  
Vol 22 (1) ◽  
pp. 23-36 ◽  
Author(s):  
Theodore Rapanos ◽  
James Duffin
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Ventilatory Response ◽  
Pressure Threshold ◽  
Partial Pressures ◽  
Progressive Hypoxia ◽  
End Tidal ◽  
Peripheral Chemoreflex ◽  
Ventilatory Response To Hypoxia ◽  
Lower Carbon

The ventilatory response to acute progressive hypoxia below the carbon dioxide threshold using rebreathing was investigated. Nine subjects rebreathed after 5 min of hyperventilation to lower carbon dioxide stores. The rebreathing bag initially contained enough carbon dioxide to equilibrate alveolar and arterial partial pressures of carbon dioxide to the lowered mixed venous partial pressure (≈ 30 mmHg), and enough oxygen to establish a chosen end-tidal partial pressure (50-70 mmHg), within one circulation time. During rebreathing, end-tidal partial pressure of carbon dioxide increased while end-tidal partial pressure of oxygen fell. Ventilation increased linearly with end-tidal carbon dioxide above a mean end-tidal partial pressure threshold of 39 ± 2.7 mmHg. Below this peripheral-chemoreflex threshold, ventilation did not increase, despite a progressive fall in end-tidal oxygen partial pressure to a mean of 37 ± 4.1 mmHg. In Conclusion, hypoxia does not stimulate ventilation when carbon dioxide is below its peripheral-chemoreflex threshold. Key words: peripheral chemoreflex, rebreathing technique, hyperventilation

Ovine ill-thrift in Nova Scotia. 4. The survival at low oxygen partial pressure of fungi isolated from the contents of the ovine rumen

1972 ◽  
Vol 18 (7) ◽  
pp. 1119-1128 ◽  
Author(s):  
D. Brewer ◽  
J. M. Duncan ◽  
S. Safe ◽  
A. Taylor
Keyword(s):  
Carbon Dioxide ◽  
Nova Scotia ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Low Oxygen ◽  
Mucor Rouxii ◽  
Permanent Pasture ◽  
Method Of Determination ◽  
Partial Pressures

Aspergillus fumigatus, Mucor rouxii, and Sporormia minima have been isolated from the rumen contents of sheep grazing permanent pasture at Nappan, Nova Scotia. To determine the ability of these fungi to survive and grow at the low oxygen partial pressure present in the rumen, a method of determination of oxygen, nitrogen, and carbon dioxide has been developed. The lowest partial pressures of oxygen [Formula: see text] and nitrogen that could be detected were 0.0005 cm Hg and the precision of the determination was ±0.001 cm Hg. Carbon dioxide was determined with slightly less precision than achieved for oxygen and nitrogen. Using this method, respiration was detected in cultures of all the fungi named at [Formula: see text] Hg and growth was observed at [Formula: see text] Hg in the case of M. rouxii. It is concluded that all these fungi are capable of survival in the ovine rumen.

scholarly journals On the effect of carbon dioxide on geotropic curvature of the roots of Pisum sativum L

1905 ◽  
Vol 76 (510) ◽  
pp. 351-358 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Pisum Sativum ◽  
Root Growth ◽  
Partial Pressure ◽  
Vicia Sativa ◽  
Main Root ◽  
Cent Carbon Dioxide ◽  
Aerial Parts ◽  
Pisum Sativum L ◽  
Partial Pressures

Many physiologists have shown that, in general, carbon dioxide exercises a narcotic or toxic influence on vegetable protoplasm, temporarily or permanently affecting its activity, according to the partial pressure under which the gas acts. De Saussure (1), as long ago as 1804, stated that, in an atmosphere containing 8 per cent. Carbon dioxide, the growth of peas was less than in air; Böhm (2), in 1873, found that roots of Phaseolus multiflorus , after 17 days’ exposure, exhibited successively less elongation in partial pressures of 2, 5, 10, and 14 per cent. Carbon dioxide respectively, the temperature ranging between 17° and 19° C.; in each percentage named the growth was progressively less than in normal air. Montemartini (3), in 1892, working with roots of Pisum , found 7 per cent. and upwards to depress growthactivity. Chapin (4), in 1902, found the growth of roots of Pisum sativum and Vicia sativa to be diminished by 5 per cent., and arrested by 25 to 30 per cent. and upwards. Growth of the stem in the same plants was diminished by 15 per cent., and completely inhibited by 22 to 25 per cent. Experiments conducted by one of us, in conjunction with Professor Farmer, have proved that seedling peas may be kept in an atmosphere containing 20 per cent. carbon dioxide for 14 days without losing the power of renewed growth when placed in air. It is interesting to note that, in many of these plants, the plumule was destroyed, although the main root continued to grow, growth being carried on by shoots arising in the axils of the cotyledons. Brown and Escombe (5) grew plants in increased partial pressures of carbon dioxide. The anatomy of these plants was investigated by Farmer and Chandler (6), who found the growth of the aërial parts to be diminished, while root-growth was apparently unaltered. Ewart (7) observed that carbon dioxide stops protoplasmic steaming, but he does not state the percentage employed in his experiments.

scholarly journals Partial pressures of CO2 in epikarstic zone deduced from hydrogeochemistry of permanent drips, the Moravian Karst, Czech Republic

2012 ◽  
Vol 41 (1) ◽  
Author(s):  
Jiří Faimon ◽  
Monika Ličbinská ◽  
Petr Zajíček ◽  
Ondra Sracek
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Karst Cave ◽  
Limestone Dissolution ◽  
Partial Pressures ◽  
Partial Pressure Of Co2 ◽  
Moravian Karst ◽  
One Year ◽  
Karst Soils ◽  
Karst Processes

Permanent drips from straw stalactites of selected caves of the Moravian Karst were studied during one-year period. A hypothetical partial pressure of CO2 that has participated in limestone dissolution, PCO2(H)=10-1.53±0.04, was calculated from the dripwater chemistry. The value significantly exceeds the partial pressures generally measured in relevant shallow karst soils, PCO2(soil)=10-2.72±0.02. This finding may have important implications for karst/cave conservation and paleoenvironmental reconstructions.Keywords: cave, carbon dioxide, dripwater, hydrogeochemistry,hypothetical partial pressure, karst processes, karstification model.

The Effects of Oxygen Vacancy Concentration on the Mechanical Properties of Zirconia and Ceria-Based Electrolytes for SOFCs

2009 ◽  
Author(s):  
Toshiyuki Hashida ◽  
Yohei Takeyama ◽  
Kazuhisa Sato
Keyword(s):  
Mechanical Properties ◽  
Elastic Modulus ◽  
Fracture Surface ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Fracture Strength ◽  
Atmospheric Pressure ◽  
Small Punch ◽  
Testing Method ◽  
Partial Pressures

In this paper, we discuss the effects of different oxygen partial pressures on the deformation property and fracture characteristics of representative constituent materials for solid oxide fuel cells (SOFCs). The elastic modulus and fracture strength of 8 mol% yittria stabilized zirconia (8YSZ) and 10 mol% gadolinia doped ceria (10GDC) treated under different oxygen partial pressures were evaluated using the small-punch testing method in this study. The specimens of 8YSZ and 10GDC prepared by a sintering process were treated at 800 °C under an oxygen partial pressure in the range of 0.21 to 10−22 atm for 1 hour. The treated specimens were then fast cooled down to a room temperature, and their mechanical properties were measured under an atmospheric pressure condition by using the small-punch testing method. The experimental results revealed that both the elastic modulus and fracture strength of the 10GDC decreased drastically when the oxygen partial pressure of the treatment was less than 10−15 atm, whereas no significant variation in both the mechanical properties was observed for the 8YSZ. The elastic modulus and fracture strength of 10GDC for the treatment under 10−22 atm was reduced down to 10–20% of those treated under the atmospheric pressure. SEM observations revealed that the fracture surface of the 10GDC specimens was changed from transgranular mode to intergranular mode when the oxygen partial pressure was reduced, whereas the fracture surface of the 8YSZ specimens was transgranular regardless of the different oxygen partial pressures.

RESPIRATION OF FISHES WITH SPECIAL EMPHASIS ON STANDARD OXYGEN CONSUMPTION: IV. INFLUENCE OF CARBON DIOXIDE AND OXYGEN

1964 ◽  
Vol 42 (5) ◽  
pp. 847-856 ◽  
Author(s):  
F. W. H. Beamish
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Consumption ◽  
Partial Pressure ◽  
Brook Trout ◽  
Salvelinus Fontinalis ◽  
Partial Pressure Of Oxygen ◽  
Partial Pressures ◽  
Rate Of Oxygen Consumption ◽  
Standard Rate ◽  
Different Levels

Oxygen consumption was determined in relation to spontaneous activity and standard metabolism estimated by extrapolating the values to zero activity, Standard oxygen consumption was determined in relation to different partial pressures of carbon dioxide and oxygen for brook trout. Salvelinus fontinalis (Mitchill), at 10 °C, and carp, Cyprinus carpio Linnaeus, at 25 °C. In general, at each partial pressure of oxygen applied, standard oxygen consumption did not change significantly over the range of partial pressures of carbon dioxide followed. The relation for brook trout operated on a level characteristic of the partial pressure of oxygen. Although the effect of different levels of oxygen was not established for carp at 25 °C, it is presumed that the relation operated also in that species in a similar way.Acclimation to the different levels of carbon dioxide and oxygen to be tested was examined and, ordinarily, found not to change significantly the standard rate of oxygen consumption.

scholarly journals High Pressure Performance of Foil Journal Bearings in Various Gases

2008 ◽  
Author(s):  
Maxwell H. Briggs ◽  
Joseph M. Prahl ◽  
Robert Bruckner ◽  
Brian Dykas
Keyword(s):  
Carbon Dioxide ◽  
High Pressure ◽  
Atmospheric Pressure ◽  
Power Loss ◽  
Journal Bearing ◽  
Brayton Cycle ◽  
Foil Bearings ◽  
Foil Bearing ◽  
Peak Pressures

Foil bearings offer several advantages over traditional oil-lubricated bearings in closed Brayton Cycle (CBC) systems, such as those proposed for long-term space power generation. Proposed CBCs require foil bearings to use an inert gas lubricant at pressures as high as 3.0 MPa as the bearing lubricant. The High Pressure Rig (HPR) at the NASA Glenn Research Center is used to measure foil bearing power loss using potential CBC working fluids at and beyond proposed CBC peak pressures. In the current study foil journal bearing power loss is measured in helium, nitrogen, and carbon dioxide from atmospheric pressure to 4.83 MPa and at shaft speeds from 10 krpm to 42 krpm. Bearings operating in helium show no increase in power loss with increasing pressure for the conditions tested. Bearings operating in nitrogen show increases in power loss with increasing pressure at speeds above 19 krpm, while increases in bearing power loss during carbon dioxide testing were seen at 15 krpm. At speeds above these thresholds, power loss is shown to increase more rapidly in carbon dioxide than in nitrogen. Results suggest that bearing power loss performance is dependent on both gas density and shaft speed.

The mechanism of inhibition of photosynthesis by high partial pressures of oxygen in Chlorella

1966 ◽  
Vol 164 (996) ◽  
pp. 511-520 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Partial Pressure ◽  
Low Light ◽  
High Oxygen Partial Pressure ◽  
Carbon 14 ◽  
Light Intensities ◽  
Mechanism Of Inhibition ◽  
Partial Pressures ◽  
Rate Of Photosynthesis ◽  
Sugar Phosphates

The decrease in rate of photosynthesis of 14 CO 2 following a transition from 20 to 99.96% oxygen with 0.04% carbon dioxide was associated with a decrease in radioactivity of the sugar phosphates and an increase in that of glycollic acid. The effect of increasing the partial pressure of oxygen was greater at higher light intensities. At the highest light intensities used the inhibition became irreversible. When carbon-14 was incorporated into the sugar phosphates and the further metabolism of these compounds studied in carbon dioxide free conditions the main products in 20% oxygen were polyglucan and sucrose, but in the presence of high oxygen partial pressure they were glycollate and glycine. Radioactive glucose was fed in the presence of oxygen free of carbon dioxide. At low light intensities the main product was a polyglucan; at higher light intensitie sglycollic acid was formed and radioactive carbon dioxide was produced

Geometrical Construction of Auxiliary Axes in an Ellingham Diagram

2020 ◽  
Vol 856 ◽  
pp. 1-7
Author(s):  
Thamrongsin Siripongsakul ◽  
Panya Wiman ◽  
Phichai Saranyachot ◽  
Somrerk Chandra-Ambhorn
Keyword(s):  
Carbon Dioxide ◽  
Carbon Monoxide ◽  
Partial Pressure ◽  
Equilibrium Partial Pressure ◽  
Geometrical Construction ◽  
Geometrical Method ◽  
Partial Pressures ◽  
Ellingham Diagram ◽  
Set Up ◽  
Thermodynamic Derivation

To facilitate the assessment of the oxide stability in H2-H2O or CO-CO2 atmospheres, auxiliary axes are constructed in the Ellingham diagram. Based on A. Ghosh’s approach, the geometrical interpretation of the diagram is proposed for the reaction 2X + O2 = 2Y, where X and Y could be originated from H2 and H2O or CO and CO2. Two cases are considered when oxygen partial pressures are lower and higher than one bar. By a geometrical method, it is proved that with an appropriate set-up of values relating to the auxiliary axes, the axes representing the ratio between the equilibrium partial pressure of hydrogen and that of water vapour, as well as the ratio between the equilibrium partial pressure of carbon monoxide and that of carbon dioxide, can be constructed. The geometrical method on the construction of axes using thermodynamic derivation is explained in the paper.

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