Organ conversion coefficients

Cell concentration in the recycle stream, M L"3 Space coordinate, L Enzyme penetration depth, L Organism yield coefficient, i.e. mass of cells formed/mass of nutrients Axial distance from the inlet of the reactor to achieve a given conversion, L Dimensionless axial coordinate Dimensionless reactor length characteristic of operation under diffusion control Dimensionless reactor length characteristic of operation under kinetic control Dimensionless transversal coordinate Dimensionless axial coordinate. 

In general, organ doses carmot be measured directly they have to be calculated by radiation transport simulations, mostly using Monte Carlo techniques and computational models of the human body. The results of these calculations are so-called organ dose conversion coefficients, i.e., mean organ doses normalized to a measurable dose quantity, such as the CTDl (see below). 

As expected, the overall reaction rate increases with increasing catalyst volume rate. The effect can be explained in terms of the dependency of the mass transport coefficient ll on the Re munber (Eq. 12). Due to the increase of the volume hold-up of the aqueous phase, the residence time of the organic phase decreases, so that the observed conversion degrees do not change within the limits of the investigated regime. 

The partition coefficient (K ) was used for the conversion of TBT concentrations in sediment and SPM to TBT concentrations in water. This Kp for TBT was calculated by multiplying the organic carbon partition coefficient (K ) with the measured fraction organic carbon (f ). Consequently, the K value has a strong impact on the final results of the risk prognosis. Generally, in risk predictions the lowest K value is applied to calculate concentrations in water (EC, 2003). This results in a worst-case water concentration, in accordance with the precautionary principle. However, with literature values for the K of TBT ranging from 3.0 - 6.2 (Lepper, 2002), it is more appropriate to base an assessment on local measured values. In this study the... 

Furthermore, for most compounds of interest to us, the octanol molecules present as cosolutes in the aqueous phase will have only a minor effect on the other organic compounds activity coefficients. Also, the activity coefficients of a series of apolar, monopolar, and bipolar compounds in wet versus dry octanol shows that, in most cases, Yu values changes by less than a factor of 2 to 3 when water is present in wet octanol (Dallas and Carr, 1992 Sherman et al., 1996 Komp and McLachlan, 1997a). Hence, as a first approximation, for nonpolar solvents, for w-octanol, and possibly for other solvents exhibiting polar groups, we may use Eq. 6-11 as a first approximation to estimate air- dry organic solvent partition constants for organic compounds as illustrated in Fig. 6.2. Conversely, experimental KM data may be used to estimate K,aw or Kitvi, if one or the other of these two constants is known. 

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