O2 partial pressure

However, in the same temperature range and O2 partial pressure total oxidation of acrolein and propene largely predominates. This can be taken as a further support that on transition metal oxide catalysts the same oxygen species (lattice oxygen) are involved in both partial and total oxidation. 

Imaging of air flow by O2 partial pressure Aerodynamics research Temperature imaging Semiconductor manufacturing... 

It was found that 23% of Co " was oxidized to Co ". The conversion of a brucite-like material to an LDH structure was observed in response to an increase in O2 partial pressure. Anionic species, such as NO3, were intercalated between the brucite-type layers of LDHs and the extent of anion intercalation increased as a function of O2 partial pressure. 

Binding of O2 to one of the subunits of the T form leads to a local conformational change that weakens the association between the subunits. Increasing O2 partial pressure thus means that more and more molecules convert to the higher-af nity R form. This cooperative interaction between the subunits increases the O2 af nity of Hb with increasing O2 concentrations—i. e., the O2 saturation curve is sigmoidal (see p. 282). 

Red fibers provide for their ATP requirements mainly (but not exclusively) from fatty acids, which are broken down via 3-oxidation, the tricarboxylic acid cycle, and the respiratory chain (right part of the illustration). The red color in these fibers is due to the monomeric heme protein myoglobin, which they use as an O2 reserve. Myoglobin has a much higher af nity for O2 than hemoglobin and therefore only releases its O2 when there is a severe drop in O2 partial pressure (cf p.282). 

In the following, we summarize the main features of practical relevance. The position and amplitude of the activity hysteresis depends mainly on partial pressure of O2 and on the nature of the support material. The threshold temperatures of both decomposition and re-formation of PdO increase markedly with O2 partial pressure. Data on the effect of the support material are reported in Table 12.2. 

Cellular oxygen is bound by myoglobin molecules that store it until it is required for metabolic action, where upon they release it to other acceptors. Hemoglobin has a additional function, however, and that is to carry CO2 back to the lungs this is done by certain amino acid side chains, and the heme groups are not directly involved. Because the circumstances under which Hb and Mb are required to bind and release O2 are very different, the two substances have quite different binding constants as a function of O2 partial pressure (Fig.). 

Figure 3. Determination of internal area Coal C—IN NaOH 6.4 atm. O2 partial pressure, 98.3°C.

On the other hand, it is now well established that relative kinetic methods which rely on the photolysis of systems containing NO, for OH production lead to erroneously high rate constants for the reaction of OH with thiols (2) and organic sulfides (16.171 due to uncontrolled processes. In the present work the O2 partial pressure was varied between SO and 760 Torr and the NOx concentration was varied by a factor of 4. The trend in the measurements was towards higher values of the rate constants with increase in the O2 partial pressure. However, the observed increase never exceeded the total error limits of the experiments. Changing the NOx concentration had vety little effect upon the measured rate constant... 

Oxygen enters the blood in the lungs, where the partial pressure of O2 is relatively high (2.1 x 104Pa) under ideal conditions in the lungs with mixing of inhaled and nonexhaled gases, the O2 partial pressure is 1.3 x 104 Pa. It is then carried by red blood cells to the tissues where the O2 partial pressure is lowered to 4 x 103 Pa. The reactions that occur are represented as follows ... 

Figure 5.13 shows the dependence of O2 partial pressure on discharge power and the growth rate achieved for ZnO deposition at different substrate temperatures using reactive MF magnetron sputtering. The O2 partial pressure was measured with a A-probe and the discharge power was controlled at constant gas flow. The experimental conditions are summarized in Table 5.3. 

In Fig. 5.13a at high power (point A) a low O2 partial pressure ofp(C>2) = 10 mPa is achieved. The decrease in discharge power (transition from A to B) shows a continuous increase in reactive gas partial pressure. Beyond point B, a further continuous increase in reactive gas partial pressure can be achieved only by increasing the discharge power. An abrupt transition from the metallic to the oxide mode (point D) would be observed for a further decrease of discharge power. 

Similar relationships between the deposition rate, O2 partial pressure, and substrate temperature have been noted in the literature [92]. Systematic investigations of the influence of ion bombardment on Zn desorption are reported in [93]. 

An example of this problem is shown in Fig. 5.27, where the transitionmode closed-loop control of central oxygen partial pressure is performed by adjusting the discharge power. The graph shows that the central oxygen partial pressure is kept constant with high accuracy. Additional A-sensors have been used to monitor the top and the bottom O2 partial pressure. These pressures vary for the two consecutive runs by several millipascal. As a consequence, the films are neither homogeneous nor reproducible. 

The denominator here represents the distribution of the sites which are empty, oxidized and occupied by N2O. The dissociative adsorption of O2 (step 3 backward) gives rise to a square-root dependency on the O2 partial pressure. 

The selective oxidation of propene to acrolein on supported vanadia catalysts was recently investigated by combined Raman, IR, and UV-vis DR spectroscopies (Zhao and Wachs, 2006). The surface vanadia species became more reduced under these reaction conditions as compared to those of alkane ODH (vide supra) because of the greater reducing power of alkenes relative to alkanes. Consequently, the reaction rates were dependent on the O2 partial pressures, because the surface vanadia sites were... 

Evidence of non-equilibrium in H20-H2-condensed phase systems was also noted recently by Sasaki and Belton (72). They observed O2 partial pressures one to two orders of magnitude less than the equilibrium values at a temperature of 1423 K over liquid Cu. However, in the presence of a Pt wire catalyst, they were able to closely approach equilibrium at residence times not too different from those of the present mass spectrometric studies. 

Under the present experimental conditions remains almost constant through out the bed. (The change in O2 partial pressure is very small i.e 21% at the inlet and 20% at the exit of the regenerator). This reduces the rate equation further to... 

Using the values chosen by Nagle and Strickland-Constable, it is possible to explain the trends given in Fig. 21. One observes that at low temperatures kj 0 and xa 1, and for low O2 partial pressure. 

At high O2 partial pressures, x 1, the second term of Eq. (72) approaches zero, and the rate becomes zero-order with respect to po ... 

In contrast to the reducing environment of the anode, the cathode in the oxidizing environment must perform the reduction of O2 to over a wide range of O2 partial pressures. Therefore, the cathode should have a good electrical conductivity to transport the electron to the adsorbed oxygen. 

The etching of Cu metal in solutions of 500 1 DHF is linear with the concentration of dissolved Oj. Etch rates from 2 to 16 nm/min are controllable with O2 partial pressures of 0.05 to 0.65 atm ( 2.5 to 33 ppm O2). The linear behavior indicates that the reaction is limited either by the transport of O2 to the surface or the reaction of O2 and Cu at the surface to form CuO. This DHF 02 chemistry shows great promise for post Cu CMP cleans. 

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