Factors Influencing Submergence and the Heart Rate in the Frog

1964 ◽  
Vol 41 (2) ◽  
pp. 417-431
Author(s):  
D. R. JONES
Keyword(s):  
Carbon Dioxide ◽  
Heart Rate ◽  
Oxygen Concentration ◽  
Carbon Dioxide Concentration ◽  
Carbon Dioxide Content ◽  
Factors Influencing ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration ◽  
Main Factors ◽  
Critical Carbon Dioxide

1. The ability of the frog to remain submerged declines as the oxygen concentration in the water falls or the carbon dioxide content rises. The critical oxygen concentration appears to be about 5 mg./l. and the critical carbon dioxide concentration 100 mg./l. at temperatures around 10° C. 2. Submergence results in a decrease in heart rate which develops over a period of 15-30 min. but which disappears immediately the animal surfaces and breathes. The bradycardia is accentuated by oxygen lack or carbon dioxide excess. 3. During submergence the heart is influenced by two main factors, the shortage of oxygen and the cessation of breathing movements, both of which contribute to the decrease in rate. The former can still affect rate after vagotomy. The connexion between breathing and heart rate is dependent on the nervous system, though the detailed pathway is not worked out.

675. The carbon dioxide content of New Zealand Cheddar cheese

1957 ◽  
Vol 24 (2) ◽  
pp. 235-241 ◽  
Author(s):  
P. S. Robertson
Keyword(s):  
Carbon Dioxide ◽  
New Zealand ◽  
Carbon Dioxide Concentration ◽  
Cheddar Cheese ◽  
Carbon Dioxide Content ◽  
Single Strain ◽  
Open Texture ◽  
Factors Influencing ◽  
High Concentrations ◽  
Lower Temperature

Some of the factors influencing the concentration of carbon dioxide found in New Zealand Cheddar cheese have been investigated.1. Cheeses made with the use of commercial starters (containing betacocci) are characterized by a rapid increase in their carbon dioxide content during the 2 weeks following manufacture.2. Cheeses made with the use of single strain starters do not change in carbon dioxide content in the first 2 weeks following manufacture, but may ultimately contain as much carbon dioxide as commercial starter cheeses.3. High concentrations of carbon dioxide within a cheese result in an open texture, especially when the carbon dioxide is formed shortly after manufacture.4. The loss of carbon dioxide to the atmosphere is demonstrated by the existence of a carbon dioxide concentration gradient within the cheese.5. Storage of cheese at a lower temperature than is usual results in retarded carbon dioxide formation.

Role of Critical Oxygen Concentration in the β-Li3PS4–xOx Solid Electrolyte

2022 ◽  
Author(s):  
Swastika Banerjee ◽  
Manas Likhit Holekevi Chandrappa ◽  
Shyue Ping Ong
Keyword(s):  
Solid Electrolyte ◽  
Oxygen Concentration ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration

Critical Concentrations of Atmospheric Contaminants in a-Si:H and μc-Si:H Solar Cells

2010 ◽  
Vol 1245 ◽  
Author(s):  
Tsvetelina Merdzhanova ◽  
Jan Woerdenweber ◽  
Thilo Kilper ◽  
Helmut Stiebig ◽  
Wolfhard Beyer ◽  
...  
Keyword(s):  
Solar Cells ◽  
Oxygen Concentration ◽  
Short Circuit ◽  
Red Light ◽  
Chamber Wall ◽  
Light Illumination ◽  
Critical Concentrations ◽  
Process Gas ◽  
Critical Oxygen ◽  
Critical Oxygen Concentration

AbstractWe report on a direct comparison of the effect of the atmospheric contaminants on a-Si:H and μc-Si:H p-i-n solar cells deposited by plasma-enhanced chemical vapor deposition (PECVD) at 13.56 MHz. Nitrogen and oxygen were inserted by two types of controllable contamination sources: (i) directly into the plasma through a leak at the deposition chamber wall or (ii) into the process gas supply line. Similar critical concentrations in the range of 4-6×1018 cm-3 for nitrogen and 1.2-5×1019 cm-3 for oxygen were observed for both a-Si:H and μc-Si:H cells for the chamber wall leak. Above these critical concentrations the solar cell efficiency decreases for a-Si:H solar cells due to losses in the fill factor under red light illumination (FFred). For μc-Si:H cells the losses in FFred and in short-circuit current density deteriorate the device performance. Only for a-Si:H the critical oxygen concentration is found to depend on the contamination source. Conductivity measurements suggest that at the critical oxygen concentration the Fermi level is located about 0.05 eV above midgap for both a-Si:H and μc-Si:H.

Environment in stone chamber of an unexcavated tumulus and preservation of buried relics: Part 1. Environmental monitoring for simulated tumulus

2020 ◽  
pp. 174425912091390
Author(s):  
Huarong Xie ◽  
Daisuke Ogura ◽  
Hiroyuki Yasui ◽  
Nobumitsu Takatori ◽  
Shuichi Hokoi ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Environmental Monitoring ◽  
Oxygen Concentration ◽  
Carbon Dioxide Concentration ◽  
Metal Corrosion ◽  
Small Temperature ◽  
Carbon Dioxide Concentrations ◽  
Hygrothermal Environments ◽  
Term Monitoring

Japan has many unexcavated tumuli, most of which were buried along with artifacts of precious cultural heritage. For such a tumulus, it is essential to understand how changes in its exterior environment affect its interior environment, and how those interior changes affect the deterioration of the relics buried in the stone chamber. In this study, an underground space was constructed in the forest of the Katsura Campus of Kyoto University to simulate the environment of an unexcavated tumulus, and long-term monitoring was implemented in the simulated stone chamber, including the temperature, humidity, water potential, wetness, and oxygen and carbon dioxide concentrations, along with metal corrosion tests. This article is focused on environmental monitoring, and the results demonstrate that the simulated tumulus has the general characteristics of the hygrothermal environments of an unexcavated tumulus that has small temperature fluctuation and near-saturation humidity. The ceiling of the simulated chamber condensed significantly from October to April, which is related to the variations of the ceiling and floor temperatures. Also, the wetness of the walls in the simulated chamber was affected by rainfall. The oxygen concentration in the simulated stone chamber varied in the range of 13%–19% in 2015, and the variation of carbon dioxide concentration in the simulated stone chamber was contrary to the oxygen concentration and varied in the range of 3%–9% in 2016. The oxygen concentration in the stone chamber was similar to that in the surrounding soil that decreased at times of rainfall, contrary to the fluctuations in the soil water content.

Effect of oxygen concentration on the rates of photosynthesis and photorespiration of some higher plants

1973 ◽  
Vol 51 (2) ◽  
pp. 457-464 ◽  
Author(s):  
A. L. D'Aoust ◽  
D. T. Canvin
Keyword(s):  
Carbon Dioxide ◽  
Oxygen Concentration ◽  
Oxygen Tension ◽  
Higher Plants ◽  
Carbon Dioxide Concentration ◽  
Gas Mixture ◽  
Low Carbon ◽  
Leaf Material ◽  
Leaf Chamber ◽  
Effect Of Oxygen

Carbon dioxide gas exchange of leaf material was studied in the light at different oxygen tensions for two CO2 concentrations, using an isotope technique. With bean, radish, and tobacco leaves in the leaf chamber, increasing the oxygen tension resulted in a significant alteration in the 14CO2/CO2 ratio of the gas mixture leaving the leaf chamber as compared to that offered to the leaf material. On estimating the rates of “true’ and apparent photosynthesis it was found that below 5% oxygen concentration the rates were not significantly different. However, increasing the oxygen concentration of the gas mixture resulted in a proportional decrease in the rates of true and of apparent photosynthesis. The increasing oxygen tension also resulted in proportional increases in the CO2 evolution (true photosynthesis minus apparent photosynthesis). The percentage inhibition of apparent photosynthesis was greater at low carbon dioxide concentration, while the inhibition of true photosynthesis was not as sensitive to the carbon dioxide level. The inhibition of apparent photosynthesis was not entirely attributable to the increased photorespiration but was roughly equally divided between an inhibition of true photosynthesis and a stimulation of CO2 evolution in the light.However, with corn leaf material, there was no effect of oxygen concentration on both the rates of true and apparent photosynthesis; also, no large CO2 evolution could be detected as emerging from leaf in the light at any of the oxygen concentrations tested.

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