The extensive burial of biologically-produced carbon led to a buildup of surplus oxygen in the atmosphere ; estimates place the peak oxygen content as high as 35 %, compared to 21 % today.

The breathing reflex is triggered by CO < sub > 2 </ sub > concentration in the blood, not by the oxygen concentration, therefore even a small buildup of CO < sub > 2 </ sub > in the inhaled gas quickly becomes intolerable ; if a person tries to rebreathe their exhaled breathing gas, they will quickly feel an acute sense of suffocation, therefore rebreathers must absorb the CO < sub > 2 </ sub >, and add the small amount of oxygen used to maintain the required concentration of oxygen.

If the intensity of the exercise exceeds the rate with which the cardiovascular system can supply muscles with oxygen, it results in buildup of lactate and quickly makes it impossible to continue the exercise.

The excess uroporphyrinogen that lead to these lesions is primarily produced in the liver, but exposure to excess sunlight is thought to lead to the production of reactive oxygen species, disrupting the activity of uroporphyrinogen decarboxylase and contributing to the buildup of uroporphyrinogen.

Failure of an unheated sensor is usually caused by the buildup of soot on the ceramic element, which lengthens its response time and may cause total loss of ability to sense oxygen.

Oxygenic photosynthesis first evolved in this era and was accountable for the oxygen catastrophe which was to happen later in the Paleoproterozoic from a poisonous buildup of oxygen in the atmosphere, produced by these oxygen producing photoautotrophs, which evolved earlier in the Neoarchean.

A wall-stabilized high-current arc source was constructed and used to study transition probabilities of atomic hydrogen and oxygen.

Following observation of the fact that the reaction rates of supposedly identical reaction mixtures prepared on the same filling manifold and exposed under identical conditions often differed by several hundred per cent, a systematic series of experiments was undertaken to see whether the difficulty could be ascribed to the method of preparing the chlorine, to the effects of oxygen or moisture or to the effect of surface to volume ratio in the reaction tubes.

Their study showed that it was possible to transfer 3 to 4 lb of oxygen / hr. / hp.

The increase in oxygen uptake rates from 1.2 to 2.6 mg/l/hr which followed an increase in rotor speed was believed to be related to resuspension of solids which had settled at the lower rotor speeds.

One of the important aspects of this study was to determine the oxygen transfer relationships of the mechanical aerator.

The dissolved oxygen in the aeration unit was consistently high until January 29, 1961.

It was approximately one month before the belt problem was noticed and corrected, but at no time was there a deficiency of dissolved oxygen.

The maximum rate of oxygen transfer at 1.0 mg/l dissolved oxygen was calculated as 220 lb/day at a maximum rate of 9.3 Aj.

Part of the time saved was spent on a preliminary estimate for a long-distance plan to free bound oxygen in the sands of Mars to make the planet more friendly to future human generations.

Argon ( αργος, Greek meaning " inactive ", in reference to its chemical inactivity ) was suspected to be present in air by Henry Cavendish in 1785 but was not isolated until 1894 by Lord Rayleigh and Sir William Ramsay in Scotland in an experiment in which they removed all of the oxygen, carbon dioxide, water and nitrogen from a sample of clean air.

Working with Pierre-Simon Laplace, Lavoisier conducted experiments that showed that respiration was essentially a slow combustion of organic material using inhaled oxygen.

He determined that the components of water were oxygen and hydrogen, and that air was a mixture of gases, primarily nitrogen and oxygen.

He established the consistent use of the chemical balance, used oxygen to overthrow the phlogiston theory, and developed a new system of chemical nomenclature which held that oxygen was an essential constituent of all acids ( which later turned out to be erroneous ).

After the acceptance of Avogadro's hypothesis in 1860 it was understood that elements could exist as polyatomic molecules, and the two allotropes of oxygen were recognized as O < sub > 2 </ sub > and O < sub > 3 </ sub >.

Since Lavoisier's knowledge of strong acids was mainly restricted to oxoacids, such as ( nitric acid ) and ( sulphuric acid ), which tend to contain central atoms in high oxidation states surrounded by oxygen, and since he was not aware of the true composition of the hydrohalic acids ( HF, HCl, HBr, and HI ), he defined acids in terms of their containing oxygen, which in fact he named from Greek words meaning " acid-former " ( from the Greek οξυς ( oxys ) meaning " acid " or " sharp " and γεινομαι ( geinomai ) meaning " engender ").

The Lavoisier definition was held as absolute truth for over 30 years, until the 1810 article and subsequent lectures by Sir Humphry Davy in which he proved the lack of oxygen in H < sub > 2 </ sub > S, H < sub > 2 </ sub > Te, and the hydrohalic acids.

This oxygen level probably increased wildfire activity, as well as resulted in insect and amphibian gigantism -- creatures whose size is constrained by respiratory systems that are limited in their ability to diffuse oxygen.

His study of plants led him to conclude that plants had tubules similar to those he saw in insects like the silk worm ( using his microscope, he probably saw the stomata, through which plants exchange carbon dioxide with oxygen ).

The noble gases, except helium and probably neon, as well as nitrogen, oxygen and hydrogen cause a decrement in mental function, but their effect on psychomotor function ( processes affecting the coordination of sensory or cognitive processes and motor activity ) varies widely.

Newspapers and television news often describe open circuit scuba wrongly as " oxygen " equipment, probably by false analogy to airplane pilots ' oxygen cylinders.

Water probably exists in abundance in other galaxies, too, because its components, hydrogen and oxygen, are among the most abundant elements in the universe.

Water and other volatiles probably comprise much of the internal structures of Uranus and Neptune and the water in the deeper layers may be in the form of ionic water in which the molecules break down into a soup of hydrogen and oxygen ions, and deeper down as superionic water in which the oxygen crystallises but the hydrogen ions float around freely within the oxygen lattice.

In general, " amu " probably does not refer to the old oxygen standard amu, unless the material is older than the 1960's.

The next atmosphere, probably consisting largely of nitrogen ( partly in the form of ammonia ), carbon dioxide, water vapor and other gases, but no free oxygen, was produced by outgassing from volcanism, supplemented by gases produced during the late heavy bombardment of Earth by huge asteroids.

If Theia had been a separate proto-planet, it probably would have had a different oxygen isotopic signature than Earth, as would the ejected mixed material.

Though oxygen was undoubtedly released by photosynthesis well back in Archean times, it could not build up to any significant degree until chemical sinks — unoxidized sulfur and iron — had been filled ; until roughly 2. 3 billion years ago, oxygen was probably only 1 % to 2 % of its current level.

Since the whale has limited remaining oxygen supplies at the end of a long dive, it probably has limited abilities to display any normal sound avoidance behavior.

The substitution of oxygen for carbon dioxide in the atmosphere, which occurred in the Proterozoic, caused probably by cyanobacteria in the form of stromatolites, caused changes leading to the evolution of aerobic organisms.

The carbonate carbon and oxygen isotope ratios imply deposition of the carbonates from a gradually evaporating subsurface water body, probably a shallow aquifer meters or tens of meters below the surface.

Heat sources include gravitational energy released by the compression of the core, gravitational energy released by the rejection of light elements ( probably sulfur, oxygen, or silicon ) at the inner core boundary as it grows, latent heat of crystallization at the inner core boundary, and radioactivity of potassium, uranium and thorium.

It is probably related to the extant Anabaena and indicates the presence of significant free oxygen.

Many now agree that both mechanisms are probably present and complementary, or working alongside a mechanism that can detect changes in oxygen and / or carbon dioxide blood saturation.

It is also highly desirable to ensure that the intake gases do not vary significantly in oxygen content over time for safety reasons, as the compressor will probably only be safe for a limited oxygen fraction.

There are probably also physically imposed limits to the size of some organisms ; for instance, insects must be small enough for oxygen to diffuse to all parts of their bodies, flying birds must be light enough to fly, and the length of giraffes ' necks may be limited by the amount of pressure it is possible for their hearts to generate.

Interestingly, although alcohols and amines can be Brønsted-Lowry acids as mentioned above, they can also function as Lewis bases due to the lone pairs of electrons on their oxygen and nitrogen atoms.

Berkelium does not react rapidly with oxygen at room temperature, possibly due to the formation of a protective oxide layer surface.

A downside, however, would be an increase in aerobic bacteria growth due to the introduction of biomass, leading to more competition for oxygen resources in the deep sea, similar to the oxygen minimum zone.

* pale, bluish, cold and clammy skin due to insufficient oxygen

The region has weakened ultraviolet radiation, particularly the UVB ( erythrogenic rays ), and an atmosphere characterized by a high oxygen content due to the high barometric pressure.

For example, in the alveoli of mammalian lungs, due to differences in partial pressures across the alveolar-capillary membrane, oxygen diffuses into the blood and carbon dioxide diffuses out.

Breathing nitrox is not thought to reduce the effects of narcosis, as oxygen seems to have equally narcotic properties under pressure as nitrogen ; thus one should not expect a reduction in narcotic effects due only to the use of nitrox.

Burial of food can preserve it due to a variety of factors: lack of light, lack of oxygen, cool temperatures, pH level, or desiccants in the soil.

It is possible to experience hypoxia and have a low oxygen content ( e. g., due to anemia ) but maintain high oxygen partial pressure ( pO < sub > 2 </ sub >).

*** Normal anatomical shunt occur due to Thebesian veins which empty into the left ventricle and the bronchial circulation which supplies the bronchi with oxygen.

*** Low partial pressure of oxygen in the lungs when switching from inhaled anesthesia to atmospheric air, due to the Fink effect, or diffusion hypoxia.

* Histotoxic hypoxia in which quantity of oxygen reaching the cells is normal, but the cells are unable to use the oxygen effectively, due to disabled oxidative phosphorylation enzymes.

A reduction in the total binding capacity of hemoglobin to oxygen ( i. e. shifting the curve down, not just to the right ) due to reduced pH is called the root effect.

Ionization is due to soft X-ray ( 1-10 nm ) and far ultraviolet ( UV ) solar radiation ionization of molecular oxygen ( O < sub > 2 </ sub >).

are commonly hazardous simply due to the lack of oxygen in the air, a condition in mines known as blackdamp.

# Archean: a period defined by the first crustal formations ( the Isua greenstone belt ) until the deposition of banded iron formations due to increasing atmospheric oxygen content.

They have higher acidities due to the aromatic ring's tight coupling with the oxygen and a relatively loose bond between the oxygen and hydrogen.

Any unglazed areas turn black due to the carbon given off from the reduction of oxygen.

A star with a core mass too great to form a white dwarf but insufficient to achieve sustained conversion of neon to oxygen and magnesium, will undergo core collapse ( due to electron capture ) before achieving fusion of the heavier elements.

Swimming is primarily an aerobic exercise due to the long exercise time, requiring a constant oxygen supply to the muscles, except for short sprints where the muscles work anaerobically.

Fainting due to a drop in blood pressure and a decrease of the oxygen supply to the brain is a temporary loss of consciousness.