The Swimbladder of Deep-Sea Fish: The Swimbladder Wall is a Lipid-Rich Barrier to Oxygen Diffusion

1980 ◽  
Vol 60 (2) ◽  
pp. 263-276 ◽  
Author(s):  
J. B. Wittenberg ◽  
D. E. Copeland ◽  
F R. L. Haedrich ◽  
J. S. Child
Keyword(s):  
Hydrostatic Pressure ◽  
Partial Pressure ◽  
Sea Water ◽  
Teleost Fishes ◽  
Partial Pressures ◽  
The Difference ◽  
Neutrally Buoyant ◽  
Tissue Fluids ◽  
Considerable Depth ◽  
Sea Fish

The swimbladder of teleost fishes is a gas-filled sac which serves primarily to make the fish neutrally buoyant in sea water, but occasionally assumes other functions. The gas contained in the swimbladder is largely oxygen, at a pressure very close to the external hydrostatic pressure. The difference in gas partial pressure between the gaseous contents of the swimbladder and the blood and tissue fluids is large in fishes living at any considerable depth, for the hydrostatic pressure increases about 1 atm with each 10 m depth, while the partial pressures of gases in sea water and body fluids are relatively independent of depth and together give a pressure of only about 1 atm. The difference in partial pressure of oxygen alone across the wall of the swimbladder of a fish living at 3000 m depth is close to 300 atm.

Photosynthetic Activity of Leaves of Pinus radiata and Nothofagus fusca After 1 Year of Growth at Elevated CO2

1996 ◽  
Vol 23 (5) ◽  
pp. 623 ◽  
Author(s):  
KP Hogan ◽  
D Whitehead ◽  
J Kallarackal ◽  
JG Buwalda ◽  
J Meekings ◽  
...  
Keyword(s):  
Partial Pressure ◽  
Pinus Radiata ◽  
Photosynthetic Activity ◽  
Photosynthetic Capacity ◽  
Radiata Pine ◽  
Rubisco Activity ◽  
Co2 Partial Pressure ◽  
Partial Pressures ◽  
The Difference ◽  
Triose Phosphate Utilisation

Radiata pine (Pinus radiata D.Don) and red beech (Nothofagus fusca (Hook. f.) Oerst.) were grown for over 1 year at elevated (ELEV, 64 Pa) and ambient (AMB, 38 Pa) CO2 partial pressure in open-top chambers. Springtime measurements of overwintering leaves showed that light- and CO2-saturated photosynthetic rates (Amax) of pine leaves were similar for the two treatments (AMB: 6.7 � 1.08 μmol m-2 s-1, mean � 1 s.e.; ELEV: 6.6 � 0.47) but, for beech leaves, Amax was greater for AMB plants (8.8 � 0.90 μmol m-2 s-1) than for ELEV plants (6.10 � 0.71). Summertime measurements of leaves grown that spring showed that for pine, Amax was similar in the two CO2 treatments (AMB 14.9 μmol m-2 s-1 � 0.80; ELEV: 13.5 � 1.9) while, for beech, Amax was higher in AMB plants (21.0 � 1.1) than in ELEV plants (17.2 � 1.9), although the difference was not statistically significant. These results indicate downregulation of photosynthetic capacity of beech but not pine. Vcmax did not differ between treatments within species, suggesting that there was no acclimation of rubisco activity. Triose phosphate utilisation limitation may have contributed to the downregulation of Amax in beech. For pine, photosynthesis at treatment CO2 partial pressures was greater in ELEV plants in both spring and summer. For beech measured at treatment CO2 partial pressures, photosynthesis was greater in ELEV plants in summer, but was similar between treatments in the springtime.

scholarly journals NEGATIVE PRESSURE GENERATED BY OCTOPUS SUCKERS: A STUDY OF THE TENSILE STRENGTH OF WATER IN NATURE

1991 ◽  
Vol 157 (1) ◽  
pp. 257-271 ◽  
Author(s):  
ANDREW M. SMITH
Keyword(s):  
Tensile Strength ◽  
Hydrostatic Pressure ◽  
Negative Pressure ◽  
Pressure Transducer ◽  
Sea Water ◽  
Pure Water ◽  
Cavitation Threshold ◽  
Negative Pressures ◽  
The Difference

The decrease in hydrostatic pressure generated by octopus suckers adhering to wettable and non-wettable surfaces was measured using a flush-mounted miniature pressure transducer. The cavitation thresholds, or lowest sustainable pressures, of sea water on the same surfaces were also measured and were compared with the pressures generated by octopuses. It is shown that suckers can generate hydrostatic pressures below OMPa on moderately wettable surfaces. This disprovesthe commonly repeated assumption that suckers cannot produce pressures below a vacuum and suggests that the importance of suction in attachment mechanisms may have been overlooked. On epoxy, the lowest recorded pressure was −0.168MPa (0.268MPa or 2.66atm below ambient), and the octopus generated negative pressure in 35% of the pulls that were considered maximal efforts. The suckers never generated negative pressures on non-wettable surfaces. These results are in agreement with the range of pressures that sea water can sustain on the same surfaces. It is suggested, therefore, that cavitation, the failure of water in tension, limits the attachment force of suckers. The difference between the cavitation threshold of water in nature and the cavitation threshold of pure water is discussed.

Effects of hydrostatic pressure and inert gases on platelet aggregation in vitro

1990 ◽  
Vol 69 (6) ◽  
pp. 2239-2247 ◽  
Author(s):  
D. M. Pickles ◽  
D. Ogston ◽  
A. G. Macdonald
Keyword(s):  
Platelet Aggregation ◽  
Hydrostatic Pressure ◽  
Maximum Degree ◽  
Platelet Rich Plasma ◽  
Control Level ◽  
Inert Gases ◽  
Partial Pressures ◽  
Compression Cycle ◽  
Anesthetic Potency

A novel cuvette was used to subject citrated platelet-rich plasma (PRP) to high hydrostatic pressure with negligible contamination by He (used for compression of the apparatus). Aggregation was induced at pressure by ADP and quantified turbidimetrically. The maximum degree of aggregation (MDA) was reduced from a control level of 82.2 to 53.6% by exposure to 101 ATA. Because decompression bubbles did not form, aggregation was also measured immediately after a compression cycle. After exposure to 101 ATA hydrostatic pressure, platelets responded normally to ADP at 1 ATA. In a matching apparatus, PRP was equilibrated with high partial pressures of inert gases. Normal physiological plasma Po2 and pH were maintained during equilibration. N2O (5 ATA) reduced the MDA from 86.5 (control) to 58.1%. N2 (51 ATA) reduced the MDA from 74.7 (control) to 51.6%, and 101 ATA Pn2 reduced the MDA from 78.0 (control) to 32.3%. He (100 ATA) reduced the MDA from 83.6 to 38.6%. It was concluded that platelet aggregation was relatively sensitive to hydrostatic pressure and less sensitive to inert gases than predicted from their anesthetic potency ratios.

Effect of CO2 on Anti-Corrosion Property of a Polyurea Coating Modified with Organosilicone

2014 ◽  
Vol 789 ◽  
pp. 466-470
Author(s):  
Qing Hao Shi ◽  
Bing Ying Wang ◽  
Bin Zhao
Keyword(s):  
High Temperature ◽  
Partial Pressure ◽  
Composite Coating ◽  
Corrosion Test ◽  
Electrochemical Impedance ◽  
Failure Process ◽  
Corrosion Property ◽  
Corrosion Mechanism ◽  
Partial Pressures ◽  
High Temperature High Pressure

The corrosion mechanism of organic silicon modified polyurea composite coating under different CO2 partial pressures was studied using high-temperature autoclave, combined with scanning electron microscopy (SEM), adhesion tests and electrochemical impedance spectroscopy (EIS) technology. The experimental results showed that: there was no corrosion product formed on the surface of coating sample after high-temperature high-pressure corrosion test, and with the increasing of CO2 partial pressure, the coating adhesion and impedance values decline increases. Moreover CO2 partial pressure increases accelerated the failure process of polyurea composite coating system.

Recrystallization of Oxygen Contaminated Al Films

1986 ◽  
Vol 71 ◽  
Author(s):  
G.J. Van Der Kolk ◽  
M.J. Verkerk
Keyword(s):  
Grain Size ◽  
Silicon Nitride ◽  
Substrate Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Relative Increase ◽  
Partial Pressures ◽  
Average Grain Size

AbstractAl was evaporated at oxygen partial pressures, PO2, varying between 10−7 and 10−4 Pa on substrates of silicon nitride. The substrate temperature was varied between 20 °C and 250°C. The films were annealed at temperatures up to 500°C.For Al films deposited at 20°C, it was found that the average grain size decreases with increasing oxygen partial pressure. After annealing recrystallization was observed. The relative increase of grain size was less for higher values of pO2. Annealing gave rise to a broad grain size distribution.For Al films deposited at 250°C, the presence of oxygen caused the growth of rough inhomogeneous films. This inhomogeneous structure remained during annealing.

Controlled partial melting during isobaric and isothermal processing of dipcoated Bi-2212/Ag tapes

1998 ◽  
Vol 13 (12) ◽  
pp. 3580-3586 ◽  
Author(s):  
A. L. Crossley ◽  
J. L. MacManus-Driscoll
Keyword(s):  
Phase Diagram ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Partial Melting ◽  
Coulometric Titration ◽  
Processing Route ◽  
Optimum Processing ◽  
Partial Pressures ◽  
Titration Technique

A detailed study has been made of the control and optimization of partial melting of dipcoated Bi2Sr2Ca1Cu2O8+δAg0.1 (Bi-2212) tapes using reduced oxygen partial pressures. A coulometric titration technique has been employed to vary the oxygen partial pressure in a region of the phase diagram corresponding to binary melting, and the amount of partial melting has been quantified. Using this information, tapes have been processed using both isothermal and isobaric techniques. An optimum processing route was determined which combined isothermal and isobaric processes. Highly aligned material at the point of optimum melting was obtained.

Oxygen Poisoning in a Hyperbaric Environment

1970 ◽  
Vol 56 (1) ◽  
pp. 39-47
Author(s):  
J. Murray Young
Keyword(s):  
Partial Pressure ◽  
Sea Water ◽  
Signs And Symptoms ◽  
Pressure Chamber ◽  
Partial Pressure Of Oxygen ◽  
Oxygen Exposure ◽  
Rapid Decompression ◽  
Hyperbaric Environment ◽  
Biochemical Mechanisms ◽  
Oxygen Poisoning

AbstractThe biochemical mechanisms of oxygen poisoning are discussed together with the signs and symptoms produced clinically. Investigation of 35 subjects performing work (mean 02 consumption 1.4 l./min) for 40 minutes in a pressure chamber at simulated depths of 20 to 47 feet of sea water showed that this degree of exercise markedly reduced the oxygen exposure tolerance of the subjects. This investigation also showed that rapid decompression of subjects breathing oxygen can produce an exacerbation of existing symptoms and these results are discussed.It is stressed that any breathing mixture containing a partial pressure of oxygen in excess of 150 torr constitutes an environment which is hyperbaric with respect to oxygen and caution is advised in the administration of oxygen to any patient.

Effects of acetone in heparin on the multiple inert gas elimination technique

1985 ◽  
Vol 58 (4) ◽  
pp. 1143-1147 ◽  
Author(s):  
F. L. Powell ◽  
F. A. Lopez ◽  
P. D. Wagner
Keyword(s):  
Partial Pressure ◽  
Dead Space ◽  
Room Temperature ◽  
Inert Gas ◽  
Published Data ◽  
Physiological Mechanisms ◽  
Heparinized Saline ◽  
Partial Pressures ◽  
Ventilation Perfusion Ratio ◽  
Mixed Venous

We have detected acetone in several brands of heparin. If uncorrected, this leads to errors in measuring acetone in blood collected in heparinized syringes, as in the multiple inert gas elimination technique for measuring ventilation-perfusion ratio (VA/Q) distributions. Error for acetone retention [R = arterial partial pressure-to-mixed venous partial pressure (P-V) ratio] is usually small, because R is normally near 1.0, and the error is similar in arterial and mixed venous samples. However, acetone excretion [E = mixed expired partial pressure (P-E)-to-P-V ratio] will appear erroneously low, because P-E is accurately measured in dry syringes, but P-V is overestimated. A physical model of a homogeneous alveolar lung at room temperature and without dead space shows: the magnitude of acetone E error depends upon the ratio of blood sample to heparinized saline volumes and acetone partial pressures, without correction, acetone E can be less than that of less soluble gases like ether, a situation incompatible with conventional gas exchange theory, and acetone R and E can be correctly calculated using the principle of mass balance if the acetone partial pressure in heparinized saline is known. Published data from multiple inert gas elimination experiments with acetone-free heparin, in our labs and others, are within the limits of experimental error. Thus the hypothesis that acetone E is anomalously low because of physiological mechanisms involving dead space tissue capacitance for acetone remains to be tested.

Low P50 in deer mice native to high altitude

1985 ◽  
Vol 58 (1) ◽  
pp. 193-199 ◽  
Author(s):  
L. R. Snyder
Keyword(s):  
High Altitude ◽  
Significant Negative Correlation ◽  
Deer Mice ◽  
Hypoxic Stress ◽  
Hemoglobin Saturation ◽  
Partial Pressures ◽  
Theoretical Predictions ◽  
Low Altitude ◽  
The Difference

Whereas it is widely believed that animals native to high altitude show lower O2 partial pressures at 50% hemoglobin saturation (P50) than do related animals native to low altitude, that “fact” has not been well documented. Consequently, P50 at pH 7.4, PCO2(7.4), the CO2 Bohr effect, and the buffer slope (delta log PCO2/delta pH) were determined via the mixing technique in Peromyscus maniculatus native to a range of altitudes but acclimated to 340 or 3,800 m. PCO2(7.4) and buffer slope were substantially lower at high altitude. The change in P50(7.4) between acclimation altitudes was minimal (0.8% increase at 3,800 m), because of counterbalancing changes in PCO2, 2,3-diphospho-D-glycerate concentration, and perhaps other factors. At both acclimation altitudes there was a highly significant negative correlation between P50(7.4) and native altitude. Since pH in vivo probably increases slightly at high altitude, the data on P50 corrected to pH 7.4 are probably underestimates of the difference in in vivo P50 at low vs. high altitude. Hence these results corroborate theoretical predictions that low P50 is advantageous under severe hypoxic stress.

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