Reversible sink

Adsorption of vapors on test chamber walls has been previously described by means of models including two or three rate constants for adsorption/desorption processes in the ease of dynamic experiments (Dunn et al., 1988 Colombo et al., 1993) and with three adsorption/desorption constants in the case of static experiments (Colombo et al., 1993). Two rate constants describe a reversible sink whereas three rate constants describe a reversible and an irreversible (i.e. leak type) sink. However, these models did not adequately describe the sorption process(es), especially in the case of long-term tests, as resulted from two observations (Colombo et al., 1993) (a) the model with three sorption rate constants (reversible + irreversible sink) provided a better description of the experimental data than the one-sink model and (b) desorption experiments following adsorption gave strong indications that the irreversible sink was in fact slowly rever-... 

As alternative expression to be used for the terms R, A, D and X, (Guo, 1996) provides a detailed description of different source and sink sub-models in the User s Guide of his Z-30 lAQ simulator. This very useful compilation of existing widely used source and sink sub-models includes 25 source and 6 sink sub-models. The 25 source sub-models include 3 for constant source, 7 for a first-order (exponential) decay source, 3 for a higher order decaying source, 1 for an instant source, 1 for a time-varying source, 2 for ambient air as an indoor source and 8 mass transfer sub-models. The 6 sink sub-models include one irreversible and five reversible sub-models. Among the five reversible sink sub-mod-els two are equilibrium models and the remaining three compute simultaneously both adsorption and desorption rates. 

The heat reclaim packaged unit system comprises water-cooled room units with reverse cycle valves in the refrigeration circuits. The water circuit is maintained at 21-26°C, and may be used as a heat source or sink, depending on whether the individual unit is heating or cooling. (See Figure 28.11.)... 

The mixing can be performed isothermally and reversibly by sinking the apparatus in a constant temperature bath, and opposing the expansive forces of the gases by forces differing only infinitesimally from them, and applied to the piston rods. 

It is seen that in the steady state the total mass is distributed between the two reservoirs in proportion to the sink coefficients (in reverse proportion to the turnover times), independent of the initial distribution. 

Efforts to apply Equations (6) and (7) to distributions of Th isotopes in the oceans showed that the situation was more complex. For example. Bacon and Anderson (1982) measured vertical distributions of Th in the deep sea and found that both the particulate and dissolved fractions increased linearly with depth. While the former observation is predictable from Equation (7) if sinking particles continue to scavenge Th during their descent, the latter is inconsistent with Equation (6). Bacon and Anderson (1982) suggested that the data could best be explained by a reversible scavenging equilibrium maintained between dissolved and particulate Th. Thus Equation (6) must be modified to ... 

In Section 7.7.5.4, we discuss the effects of additives in the acceptor wells that create a sink condition, by strongly binding lipophilic molecules that permeate across the membrane. As a result of the binding in the acceptor compartment, the transported molecule has a reduced active (unbound) concentration in the acceptor compartment, cA(t), denoted by the lowercase letter c. The permeability equations in the preceding section, which describe the nonsink process, are inappropriate for this condition. In the present case, we assume that the reverse transport is effectively nil that is, CA(t) in Eq. (7.1) may be taken as cA(t) 0. As a result, the permeability equation is greatly simplified ... 

The main disadvantage of the perfect sink model is that it can only be applied for irreversible deposition of particles the reversible adsorption of colloidal particles is outside the scope of this approach. Dahneke [95] has studied the resuspension of particles that are attached to surfaces. The escape of particles is a consequence of their random thermal (Brownian) motion. To this avail he used the one-dimensional Fokker-Planck equation... 

The main species in solution has been identified to be the hydrido-alkynyl complex [IrH(C2Ph)(cod)(//2-iPrPCH2CH2OMe)]+BF4 (23). This is, however, only a sink that results from direct reaction of 22 with the 1-alkyne, draining the active catalyst from the system. The catalysis proceeds via the dihydrido-diene intermediate [IrH2(cod)(//2- PrPCH2CH2OMe)]+ BF4 (24), which reacts reversibly with the alkyne to yield the hydrido-iridium-styryl complex 25, followed by a rate-determining reaction of this hydrido-vinyl species with hydrogen to re-... 

The reversible work available from the condenser using the working fluid temperature Th (average value) and the heat sink temperature T2 is... 

The fuel cells and heat sinks occupy more than 80% of the straight line distance between the lower- and the upper-reversal points. Then the gravity forces are particularly effective for the transport of the fuel or the oxidizing agent. 

Fig. 6.4 Reversible interconversion of amino acid and keto acid. Conjugation of the imine bond in the aldimine with the electron sink of the pyridine ring plus protonation of the pyridine nitrogen as well as the metal ion - all this results in weakening of the C-H bond of the amino acid residue. Thus, also catalyzed is a-proton exchange, racemization of a chiral center at the a-carbon atom and decarboxylation of the appropriate amino acid. ...

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