Ambient Pressure Effects on Atmospheric Oxygen Levels in Patrol Submarines

1977 ◽  
Vol 63 (2) ◽  
pp. 101-104
Author(s):  
E. J. Jolly
Keyword(s):  
Atmospheric Oxygen ◽  
Ambient Pressure ◽  
Pressure Effects ◽  
Oxygen Generation ◽  
Oxygen Levels

AbstractThis article describes a submarine trial which demonstrates the importance of considering ambient pressure in a diesel-electric submarine when determining submerged time allowed before commencing oxygen generation.

Plants at Sub-Atmospheric Oxygen-Levels

Nature ◽  
1963 ◽  
Vol 198 (4887) ◽  
pp. 1288-1290 ◽  
Author(s):  
S. M. SIEGEL ◽  
L. A. ROSEN ◽  
C. GIUMARRO
Keyword(s):  
Atmospheric Oxygen ◽  
Oxygen Levels

A case for low atmospheric oxygen levels during Earth's middle history

2018 ◽  
Vol 2 (2) ◽  
pp. 149-159 ◽  
Author(s):  
Noah J. Planavsky ◽  
Devon B. Cole ◽  
Terry T. Isson ◽  
Christopher T. Reinhard ◽  
Peter W. Crockford ◽  
...  
Keyword(s):  
Chemical Composition ◽  
Conceptual Framework ◽  
Environmental Conditions ◽  
Atmospheric Oxygen ◽  
Critical Factor ◽  
Planetary Surface ◽  
Surface Oxygen ◽  
Oxygen Levels ◽  
Early Diversification ◽  
Atmospheric Level

The oxygenation of the atmosphere — one of the most fundamental transformations in Earth's history — dramatically altered the chemical composition of the oceans and provides a compelling example of how life can reshape planetary surface environments. Furthermore, it is commonly proposed that surface oxygen levels played a key role in controlling the timing and tempo of the origin and early diversification of animals. Although oxygen levels were likely more dynamic than previously imagined, we make a case here that emerging records provide evidence for low atmospheric oxygen levels for the majority of Earth's history. Specifically, we review records and present a conceptual framework that suggest that background oxygen levels were below 1% of the present atmospheric level during the billon years leading up to the diversification of early animals. Evidence for low background oxygen levels through much of the Proterozoic bolsters the case that environmental conditions were a critical factor in controlling the structure of ecosystems through Earth's history.

scholarly journals Metabolic Activity of Human Embryos after Thawing Differs in Atmosphere with Different Oxygen Concentrations

2020 ◽  
Vol 9 (8) ◽  
pp. 2609
Author(s):  
Michal Ješeta ◽  
Andrea Celá ◽  
Jana Žáková ◽  
Aleš Mádr ◽  
Igor Crha ◽  
...  
Keyword(s):  
Amino Acids ◽  
Amino Acid ◽  
Oxygen Concentration ◽  
Atmospheric Oxygen ◽  
Blastocyst Stage ◽  
Human Embryos ◽  
Total Amino Acid ◽  
Oxygen Levels ◽  
Amino Acid Turnover ◽  
Cultivation Environment

The vitrification of human embryos is more and more frequently being utilized as a method of assisted reproduction. For this technique, gentle treatment of the embryos after thawing is crucial. In this study, the balance of amino acids released to/consumed from the cultivation media surrounding the warmed embryos was observed in the context of a cultivation environment, which was with the atmospheric oxygen concentration ≈20% or with a regulated oxygen level—hysiological (5%). It is the first time that total amino acid turnover in human embryos after their freezing at post compaction stages has been evaluated. During this study, progressive embryos (developed to blastocyst stage) and stagnant embryos (without developmental progression) were analyzed. It was observed that the embryos cultivated in conditions of physiological oxygen levels (5% oxygen) showed a significantly lower consumption of amino acids from the cultivation media. Progressively developing embryos also had significantly lower total amino acid turnovers (consumption and production of amino acids) when cultured in conditions with physiological oxygen levels. Based on these results it seems that a cultivation environment with a reduced oxygen concentration decreases the risk of degenerative changes in the embryos after thawing. Therefore, the cultivation of thawed embryos in an environment with physiological oxygen levels may preclude embryonal stagnation, and can support the further development of human embryos after their thawing.

scholarly journals No evidence for high atmospheric oxygen levels 1,400 million years ago

2016 ◽  
Vol 113 (19) ◽  
pp. E2550-E2551 ◽  
Author(s):  
Noah J. Planavsky ◽  
Devon B. Cole ◽  
Christopher T. Reinhard ◽  
Charles Diamond ◽  
Gordon D. Love ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Oxygen Levels

scholarly journals The oxic degradation of sedimentary organic matter 1400 Ma constrains atmospheric oxygen levels

2017 ◽  
Vol 14 (8) ◽  
pp. 2133-2149 ◽  
Author(s):  
Shuichang Zhang ◽  
Xiaomei Wang ◽  
Huajian Wang ◽  
Emma U. Hammarlund ◽  
Jin Su ◽  
...  
Keyword(s):  
Atmospheric Oxygen ◽  
Carbon Mineralization ◽  
Black Shales ◽  
Depositional Environments ◽  
Iron Speciation ◽  
North China Block ◽  
High Hydrogen ◽  
Oxygen Levels ◽  
The North ◽  
Xiamaling Formation

Abstract. We studied sediments from the ca. 1400 million-year-old Xiamaling Formation from the North China block. The upper unit of this formation (unit 1) deposited mostly below storm wave base and contains alternating black and green-gray shales with very distinct geochemical characteristics. The black shales are enriched in redox-sensitive trace metals, have high concentrations of total organic carbon (TOC), high hydrogen index (HI) and iron speciation indicating deposition under anoxic conditions. In contrast, the green-gray shales show no trace metal enrichments, have low TOC, low HI and iron speciation consistent with an oxygenated depositional setting. Altogether, unit 1 displays alternations between oxic and anoxic depositional environments, driving differences in carbon preservation consistent with observations from the modern ocean. We combined our TOC and HI results to calculate the differences in carbon mineralization and carbon preservation by comparing the oxygenated and anoxic depositional environments. Through comparisons of these results with modern sedimentary environments, and by use of a simple diagenetic model, we conclude that the enhanced carbon mineralization under oxygenated conditions in unit 1 of the Xiamaling Formation required a minimum of 4 to 8 % of present-day atmospheric levels (PAL) of oxygen. These oxygen levels are higher than estimates based on chromium isotopes and reinforce the idea that the environment contained enough oxygen for animals long before their evolution.

Reduction of acetylene by stationary cultures of free-living Rhizobium sp. under atmospheric oxygen levels

1976 ◽  
Vol 22 (7) ◽  
pp. 949-952 ◽  
Author(s):  
William R. Evans ◽  
Donald L. Keister
Keyword(s):  
Atmospheric Oxygen ◽  
Maximal Activity ◽  
Free Living ◽  
Oxygen Levels ◽  
Specific Activities ◽  
Rhizobium Sp ◽  
Oxygen Concentrations

The reduction of acetylene to ethylene by stationary (non-shaking) cultures of free-living rhizobia under atmospheric oxygen levels has been demonstrated. Under these conditions the development of the activity is inhibited by 10 mM NH4Cl and about 20% of oxygen is required for maximal activity. When the stationary cultures were shaken, oxygen concentrations of 1% and higher were found to be inhibitory. Specific activities of 20 and 40 nmol of acetylene reduced h−1 mg−1 protein were observed.

Case Study of Ambient Pressure Effects on Pore Shape in Solid

2017 ◽  
Vol 31 (4) ◽  
pp. 796-804 ◽  
Author(s):  
Shih-Yen Hsiao ◽  
Peng-Sheng Wei
Keyword(s):  
Ambient Pressure ◽  
Pressure Effects ◽  
Pore Shape
Sign in / Sign up

Export Citation Format

Share Document