Facilitation factor

The assessment of risk of the potential incidence or escalation of conflict is called integrated because of the broad scale of factors that are considered (political, economic, social, demographic and environmental. The integrated risk assessment manages the complexity in the relationship between the consequences of stress and inhibiting or facilitating factors in order to determine which factor has the most potential impact on the incidence or escalation of conflict. 

Alcohol abuse Alcohol abuse is the most common cause of cirrhosis. Nevertheless, no more than 40-60% of alcoholics contract the disease. Thus genetic factors must also be involved in the development of alcoholic cirrhosis. Alcohol itself can be a facilitative factor or cofactor. Moreover, so-called additives contained in various alcoholic beverages in widely different quantities may also be of greater importance than has hitherto been assmned. (100, 171, 186) (s. pp 528, 532) (s. fig. 28.13, 28.14)... 

Hyperpyrexia has been attributed to famotidine, but the patient had pre-existing cerebral trauma as a facilitating factor (SEDA-16, 422). 

Facilitation factors are commonly used as measures of the effectiveness of carrier-mediated transport. Here, the facilitation factor f is defined as... 

Figure 3. Facilitation factor as a function of salt concentration...

Facilitation factor of backward extraction at LM-receiving phase interface (l+Kbex[Se4])(l+Kbex[SH])... 

Reinhoudt and co-workers (51) targeted O2 and prepared water-soluble models of heme-protein active sites. These were self-assembling, heterodimeric capsules of cationic Co(II) porphyrin (27) and tetrasulfonato calix[4]arene (28) (Fig. 12). A millipore VMWP membrane, loaded with an aqueous solution of 27 (2 mA/), 28 (6mM), and 1-methyl imidazole (20 mM), showed a facilitated transport of O2. The facilitation factor of 1.15 and the O2/N2 selectivity of... 

In sum, the zealous over-compliance with international acidification norms by the Czech Republic was driven by strong domestic concern and policies that mandated strict emission standards and neutralized the opposition of industry through policy concessions and subsidies. International norms provided a commitment mechanism for domestic reformers and a model for regulations. Beyond these facilitating factors, the close correspondence between domestic preferences and international commitments was the single most important factor that explains the high compliance with European acid rain standards in the Czech Republic. The significant acidi-... 

The major output of interest is the solute flux through the liquid membrane. Often, this flux is described In a dimensionless fashion as a facilitation factor (F). F Is defined as the total solute flux with carrier present divided by the diffuslonal flux of solute alone. 

Smith and Quinn (35) and Hoofd and Kreuzer (46) Independently developed analytical solutions for the facilitation factor which holds over a range In properties and operating conditions. Smith and Quinn obtained their solution by assuming a large excess of carrier. This allowed them to linearize the resulting differential equations. Hoofd and Kreuzer separated their solution into two parts a reaction-limited portion which is valid near the interface and a diffusion-limited portion within the membrane. Both groups obtained the same result for the facilitation factor. Hoofd and Kreuzer ( T) then extended their approach to cylinders and spheres. Recently, Noble et al. (48) developed an analytical solution for F based on flux boundary conditions. This solution allows for external mass transfer resistance and reduces to the Smith and Quinn equation In the limit as the Sherwood number (Sh) becomes very large. 

Way et al. ( ) applied this analytical model to predict facilitation factors for 00 facilitated transport In Ion exchange membranes. As shown In Figure 8, there was good agreement between experimental and predicted facilitation factors. 

Way ( ) applied the competitive transport model of Nllya and Noble ( ) to the prediction of facilitation factors for competitive transport of COj and HjS In Ion exchange membranes containing organic amine carriers. The results of the numerical simulations are shown in Table 2. The agreement Is very good for CO, and qualitative for H,S. 

Figure 8. Comparison of predicted carbon dioxide facilitation factors to experimental data.

Table 2. Comparison of Experimental Facilitation Factors for Competitive Transport with Theory...

An alternative method for the preparation of facilitated transport membranes is the subject of the first paper in this section. Way and Noble (113) report a study of H,S facilitated transport in reactive ion exchange membranes. The use of a perfluorosulfonic acid lEM as a support for organic amine counterions avoids problems of solvent and carrier loss often encountered with ILMs. High carrier loadings of greater than 8 M in the lEMs were attained which helped to account for the high facilitation factors of 26.4 which are observed at low partial pressures. An analytical model predicted facilitation factors in excellent agreement with the experimental data. Separation factors for HjS over CH., of 792 to 1200 are reported. Implications of the mathematical model for industrial applications are also discussed. 

The parameters K, e and a can be used to calculate a facilitation factor, F, which is defined as ... 

By following electronic spectral changes of Fe(TIM) In BN upon reaction with CO as a function of time the rates and equilibrium constants for the complexatlon reaction were determined (18). The diffusion coefficients for the carrier cuid the CO-complex as well as the equilibrium constant were measured using cyclic voltammetry and rotating disk voltammetry. These physical constants were incorporated In the optimization model which predicted a facilitation factor F- 1.12. This data is summarized In Table I. 

Table I. Summary of Physical Properties and Facilitation Factors for Fe(II)(TIM) and Derivatives...

The parameters Sh, a, and 0 are the wall Sherwood number, the maximum facilitation factor and the dimensionless equilibrium constant. The equilibrium facilitation factor is given as... 

The effect of changing the value of the dimensionless maximum facilitation factor, o, and the dimensionless equilibrium constant, 8, is given in Figs. 3 and 4. The mixing cup concentration is strongly influenced by the value of a. The maximum facilitation factor can be increased by dissolving more carrier in the membrane... 

Figure 3. The effect of the maximum facilitation factor on the dimensionless mixing-cup concentration for Sh =1, 6 = 15.

As the fluid flows through the exchanger, the concentration of the solute changes along the membrane. As a consequence, the flux through the membrane, which is imposed by boundary condition number three, changes as the equilibrium facilitation factor changes. 

Figure 5. Dependency of the equilibrium facilitation factor on the dimensionless axial distance and a. The intercept at x = 0, is a/(l+B) for each curve. Sh, = 1, B = 15.

Figure 7. Equilibrium facilitation factor as a function of the wall Sherwood nunber and dimensionless axial distance.

Equilibrium facilitation factor Half-width of channel height... 

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