Second gas effect

This occurs as a result of the concentration effect and so it is always useful to describe the concentration effect first, even if being questioned directly on the second gas effect. If there is another gas present in the alveolus, then it too will be concentrated by the relatively rapid uptake of N20 into the blood. 

The alveolar tension of other anesthetic gases also rises more rapidly (second gas effect) when an anesthetic such as N2O is present in high concentration. These gases are also subject to the increased inflow (pulling in of fresh gases) as N2O is taken up into the blood. 

The uptake of any other inhalation agent, given at the same time as nitrous oxide, is accelerated by the rate of uptake of nitrous oxide. This is termed the second gas effect (44). Direct pharmacodynamic interactions do not... 

Epstein RM, Rackow H, Salanitre E, Wolf GL. Influence of the concentration effect on the uptake of anesthetic mixtures the second gas effect. Anesthesiology 1964 25 364-71. 

Nitrous oxide is very insoluble in blood and other tissues (Table 13-1). This results in rapid equilibration between delivered and alveolar anesthetic concentrations and provides for rapid induction of anesthesia and rapid emergence following discontinuation of administration. The rapid uptake of N2O from alveolar gas serves to concentrate coadministered halogenated anesthetics this effect (the second gas effect ) speeds induction of anesthesia. On discontinuation of administration, nitrous oxide gas can diffuse from blood to the alveoli, diluting Oj in the lung. This can produce an effect called diffusional hypoxia. To avoid hypoxia, 100% Oj rather than air should be administered when N O is discontinued. 

Note that there is no net change in the number of moles of gas in this equilibrium. Therefore, by Le Chatelier s principle, this reaction will be independent of external pressure (ignoring second-order effects due to gas imperfections). Under these conditions the N of the expl will... 

Carbon dioxide is absorbed in alkaline water from a mixture consisting of 30% CO2 and 70% Nj and the mass transfer rate is 0.1 kmobs. The concentration of CO2 in the gas in contact with the water is effectively zero. The gas is then mixed with an equal molar quantity of a second gas stream of molar composition 20% CO2, 50%, N2 and 30% H2. What will be the new mass transfer rate, if the surface area, temperature and... 

The cancellation of gas phase spectral features using the "half plate design Is far superior to methods Involving a second gas cell placed In the reference beam. This Is because the gas density and Its rotational state population will differ In the two cells for different sample (and therefore gas) temperatures. For high sensitivity measurements, these effects can be difficult to handle using two cells. 

The Hatta criterion compares the rates of the mass transfer (diffusion) process and that of the chemical reaction. In gas-liquid reactions, a further complication arises because the chemical reaction can lead to an increase of the rate of mass transfer. Intuition provides an explanation for this. Some of the reaction will proceed within the liquid boundary layer, and consequently some hydrogen will be consumed already within the boundary layer. As a result, the molar transfer rate JH with reaction will be higher than that without reaction. One can now feel the impact of the rate of reaction not only on the transfer rate but also, as a second-order effect, on the enhancement of the transfer rate. In the case of a slow reaction (see case 2 in Fig. 45.2), the enhancement is negligible. For a faster reaction, however, a large part of the conversion occurs in the boundary layer, and this results in an overall increase of mass transfer (cases 3 and 4 in Fig. 45.2). 

The transition region might arise from effects such as those illustrated in Figure 11, while Figure 12 illustrates possible effects of exposing the surface depicted in Figure 10 to a second gas. 

The second important effect is that irradiation absorption generates active states of the photoadsorption centers with trapped electrons and holes. By definition (Serpone and Emeline, 2002) the photoadsorption center is a surface site which reaches an active state after photoexcitation and then it is able to form photoadsorbed species by chemical interaction with substrate (molecules, or atoms, or ions) at solid/fluid interface. In turn, the active state of a surface photoadsorption center is an electronically excited surface center, i.e. surface defect with trapped photogenerated charge carrier that interacts with atoms, molecules or ions at the solid/gas or solidfiquid interfaces with formation of chemisorbed species. ... 

These experiments open the possibility that some of the scatter in the comparison of natural gas exchange measurements with wind speed may be due to the effect of surfactants. If a way to remotely characterize wave slopes is devised, then it may give insight into second-order effects on the transfer velocity caused by surfactants. Another implication is that pollution of the seas by petroleum may have an inhibitory effect on the global gas exchange rate. 

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