Enrichment ratio values

Fig. 6.5. Peak spreading strongly affects enrichment ratio at fixed probability of retention. The coefficient of variance CV is equal to the ratio of the standard deviation to the mean, and is a measure of peak breadth. For example, in both curves shown in Fig. 6.3 the CV is 1.0. The enrichment ratio was calculated for a situation in which mutant fluorescence intensity was double wild-type fluorescence intensity, the mutant was initially present at 1 in 106 cells, and the probability of retention was fixed at 95 %. The logarithmic fluorescence intensity was assumed to follow a Gaussian distribution. Fixing the probability of retention defines the cutoff fluorescence value for screening at a given CV. Enrichment ratio drops precipitously with increasing CV, as the mutant and wild-type fluorescence distributions begin to overlap. At a CV of 0.2, the enrichment factor is 600. However, at a CV of 0.4, the enrichment factor has dropped to 3 Clearly, every effort should be expended to minimize peak spreading and subsequent overlap of the mutant and wild-type fluorescence distributions.

Figure 18 Plots of maximuni enrichment coefficient values versus flow ratios.

It is practically impossible to obtain reliable comparative values for the HETP s of packed columns and for the plate efficiencies (or average enrichment ratios) of ])late colunms from data published in the literature, since these data refer to various test mixtures and were obtained under different conditions. Only in rare cases are all the necessary data, mentioned in section 4.10, given. Some agreement on a standardized... 

The residence time for retinol in the test subject was predicted by the compartmental model to be 474 days. The residence time of 474 days is in excellent agreement with the 460 day MST that can be calculated from the data of Song et al. (1995) using the enrichment ratio method (Cobelli and Saccomani, 1992). Also, an MST of 105 to 337 days can be calculated from the half-life values (75 to 241 days) of body vitamin A reported by Sauber-lich et al. (1974) who depleted human subjects with vitamin A-deficient diets. At the same time the empirical description predicted the MST for retinol to be 26 days. While the reason for such a large discrepancy in MST (474 versus 26 days) between the compartmental model and the empirical description prediction is unclear, it is not likely to be accounted for by slight errors in estimating the final slope of the plasma retinol-d4 decay curve. Because the compartmental model embodies several features of retinol metabolism de novo production and release of retinol can occur in unobservable compartments, etc.) in addition to plasma retinol concentrations, its predicted MST is more likely to better reflect the dynamics of retinol metabolism. 

Effectiveness, separation effect (enrichment ratio, NTS, HETP-value)... 

Figure 8. Enrichment ratios (3+9)(3+9+7) predicted by simulation model at two levels of PP-ribose-P, Compare with observed values in Fig. 2, and note that the simulation model omits %-l values from the denominator, X = 0.015625.

Figure 1.53 presents the example of soya protein enrichment with sulfur-containing amino acids through adulteration with the partial hydrolysate of wool keratin. The PER (protein efficiency ratio) values of such plastein products are significantly improved, as is seen in Table 1.42. 

Since perfect separation requires //j = 0 for bothj = 1,2 simultaneously, improved separation in a given problem implies decreasing values of t/j. If it is desired that the separation index value should increase as separation improves, one can define an enrichment ratio tjj by utilizing the definition of rjj (Boyde, 1971) ... 

Other Nuclei. Although most nmr experiments continue to involve H, or both, many other nuclei may also be utilized Several factors, including the value of I for the nucleus, the magnitude of the quadmpolar moment, the natural abundance and magnetogyric ratio of the isotope, or the possibihty of preparing enriched samples, need to be considered. The product of the isotopic parameters can be compared to the corresponding value for providing a measure of relative sensitivity or receptivity. Table 1 summarizes these factors for a number of isotopes. More complete information may... 

For the case under consideration, where the value of a — 1 is quite small, it follows that everywhere in the cascade, except possibly at the extreme ends, the stage upflow is many times greater than the product withdrawal rate. Thus L/ L — P) can be set equal to unity. Furthermore when the value of a — 1 is small, the stage enrichment can be approximated by the differential ratio dx/dn without appreciable error. The gradient equation for the... 

Time-Dependent Cascade Behavior. The period of time during which a cascade must be operated from start-up until the desired product material can be withdrawn is called the equiUbrium time of the cascade. The equiUbrium time of cascades utilizing processes having small values of a — 1 is a very important quantity. Often a cascade may prove to be quite impractical because of an excessively long equiUbrium time. An estimate of the equihbrium time of a cascade can be obtained from the ratio of the enriched inventory of desired component at steady state, JT, to the average net upward transport of desired component over the entire transient period from start-up to steady state, T . In equation form this definition can be written as... 

The efficiency of a distillation apparatus used for purification of liquids depends on the difference in boiling points of the pure material and its impurities. For example, if two components of an ideal mixture have vapour pressures in the ratio 2 1, it would be necessary to have a still with an efficiency of at least seven plates (giving an enrichment of 2 = 128) if the concentration of the higher-boiling component in the distillate was to be reduced to less than 1% of its initial value. For a vapour pressure ratio of 5 1, three plates would achieve as much separation. 

An alternative way to view the oxygen enrichment of the vapor relative to the condensed phase Is to calculate the oxygen-to-plutonium ratio of the gas, R(gas), with Eq. (2). The value of R(gas) exceeds that of the condensed phase with which It Is In equilibrium by a large amount. Like the U/0 system, this oxygen enrichment of the vapor relative to the condensed phase Is Increasing with temperature. One Implication of these results Is that the condensed-phase and vapor-phase compositions will depend upon the extent of vaporization of a sample with overall composition given by 0/Pu = 2 - x. 

---