Oxygen deficiency/depletion

OXYGEN DEFICIENCY Depletion of oxygen content in an atmosphere to below the normal 21%. Exposure to <18% must not be permitted. Concentrations 6% to 10% oxygen can lead to loss of consciousness. 

The next most important aspect is the issue of the oxygen depletion in the chamber. The atmosphere inside the closed compartment often becomes oxygen-deficient before the test ends. Thus, after the oxygen level gets below 14% burning often ceases. This means that, when testing thick samples (typically multi-layered materials or composites) one of the components may not get to burn at all. 

When metal parts make contact, or when metals contact a nonmetallic part such as a gasket, the crevice formed at the point of contact can become a corrosion site. Corrosive attack at this site is usually more severe than the surrounding area due to factors such as oxygen deficiency, acidic changes, or inhibitor depletion. Using... 

In temperate lakes phytoplanktonic blooms occur in response to the seasonal availability of nutrients, which is controlled by stratification of the water column (see Section 3.2.2b). The situation is, therefore, similar to seasonal thermocline development and decline in temperate oceans. During summer stratification nutrients in the epilimnion become depleted. During the spring and autumn overturns, nutrient-rich (and oxygen-deficient) waters of the hypolimnion mix with the epilimnion and fuel phytoplanktonic blooms, primarily in the spring. 

Electron microscopic observations of the Ortho-III phase have been reported far less than of the Ortho-II phase [7.8, 7.34, 7.35]. Clear evidence for the occurrence of this phase is given in the [001] diffraction of Fig. 7.4(d). Due to the short structural coherence length of this phase, the results could not be confirmed either by X-ray, or by neutron diffraction. The Ortho-III phase ideally appears at an oxygen deficiency 0 =, and compared to the Ortho-I phase, has one out of three CuiOi chains depleted of oxygen in an ordered succession. (See Fig. 7.2(c)). Lattice parameters are am 3ai, bm b and cm c. The tripling of the unit-cell is reflected in the diffraction pattern by the appearance of two superstructure spots at positions h+ kl and h + kl. Superstructure spots for the Ortho-III phase are always very broad, due to substantial disorder in the cell-tripling alternation, or to the limited size of the domains. 

SB-2 Oxygen-Deficient Atmospheres, Depletion of the oxygen content in air by combustion or displacement with inert gas is a potential hazard to personnel throughout industry. This bulletin deals with recommended practices for the protection of personnel working in a potentially oxygen-deficient atmosphere. Supplemental to CGA P-14. (2 pages)... 

This form of corrosion can result because of a deficiency of oxygen in the crevice, acidity changes in the crevice, buildup of ions in the crevice, or depletion of an inhibitor. 

Zinc protoporphyrin IX is a normal metabolite that is formed in trace amounts during haem biosynthesis. However, in iron deficiency or in impaired iron utilization, zinc becomes an alternative substrate for ferrochelatase and elevated levels of zinc protoporphyrin IX, which has a known low affinity for oxygen, are formed. This zinc-for-iron substitution is one of the first biochemical responses to iron depletion, and erythrocyte zinc protoporphyrin is therefore a very sensitive index of bone-marrow iron status (Labbe et ah, 1999). In addition, zinc protoporphyrin may regulate haem catabolism by acting as a competitive inhibitor of haem oxygenase, the key enzyme of the haem degradation pathway. However, it has been reported... 

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