Fractional absorption

Enzymes are obtained from plants, animals and micro-organisms by extraction with a suitable solvent, preferably after the cell structure has been destroyed by drying or grinding. They can be purified by precipitation and resolution and by fractional absorption and elution. Many enzymes have been obtained crystalline. 

The left-hand side of Eq. (14-55) represents the efficiency of absorption of arw one component of the feed-gas mixture. If the solvent oil is denuded of solute so that Xo = 0, the left-hand side is equal to the fractional absorption of the component from the rich feed gas. When the number of theoretical plates N and the hquid and gas rates L i and G, f have been fixed, the uractional absorption of each component may be computed directly and the operating lines need not be placed by trial and error as in the graphic approach described earlier. 

This equation can be employed for estimating the fractional absorption of the more volatile components whenever the value of A for the component is smaller than the value of A for the key component by a factor of 3 or more. 

Figure 8-83. Allowable mass velocity for fractionation, absorption, and stripping columns.

Fig. 2.8 (a) Fractional absorption of a Mossbauer absorption line as function of the effective absorber thickness t. (b) The depth of the spectrum is determined by fs. The width for thin absorbers, t 1, is twice the natural line width F of the separate emission and absorption lines (see (2.30)). AE is the shift of the absorption line relative to the emission line due to chemical influence... 

The relative absorption depth of the Mossbauer line is determined by the product of the recoU-free fraction/s of the Mossbauer source and the fractional absorption z t) of the sample, abs = fs-e f), where c(t) is a zeroth-order Bessel function ((2.32) and Fig. 2.8). Since c(t) increases Unearly for small values of t, the thin absorber approximation, c(t) t/2, holds up to t 1. On the other hand, values as small as t = 0.2 may cause already appreciable thickness broadening of the Mossbauer lines, according to (2.31), Fexp + 0.135t). In practice, therefore the sample... 

A relative simple solution can be obtained for absorbers with low signal N, if the background contribution N can be neglected. With equation (2.32) for the fractional absorption in thin absorbers, i.e., s(t) t/2, the signal amplitude can be written as ... 

Absorption Coefficient—Fractional absorption of the energy of an unscattered beam of x- or gamma-radiation per unit thickness (linear absorption coefficient), per unit mass (mass absorption coefficient), or per atom (atomic absorption coefficient) of absorber, due to transfer of energy to the absorber. The total absorption coefficient is the sum of individual energy absorption processes (see Compton Effect, Photoelectric Effect, and Pair Production). 

Only a subset of the parameter values in the O Flaherfy model require inputs from the user to simulate blood and tissue lead concentrations. Lead-related parameters for which values can be entered into the model include fractional absorption from the gastrointestinal tract partition coefficients for lead in nonbone tissues and in the surface region of bone maximum capacity and half-saturation concentration for capacity-limited binding in the erythrocyte elimination clearance fractional clearance of lead from plasma into forming bone and the restricted permeability coefficients for lead diffusion within bone, from plasma into bone, and from bone into plasma (O Flaherty 1991a). 

Inhaled tetraethyl and tetramethyl lead vapors behave as gases in the respiratory tract and, as a result, their pattern and extent of deposition and absorption differ from that of inhaled inorganic lead particles (EPA 1994a Overton et al. 1987 Overton and Miller 1988). These differences result in a higher fractional absorption of inhaled tetraethyl and tetramethyl lead (Heard et al. 1979). 

The degradation and formation of nonabsorbable drug complexes in the intestinal lumen is the third factor, in addition to dissolution and permeability, which could affect fraction absorption. Limitations of bioavailability due to these factors seem to be less frequent compared with the two other main factors. Regulatory guidelines for BCS-based biowaivers still ask for in vitro studies of luminal degradation in relevant test media, whereas specific binding studies are not required [17]. 

Animals Age at administration Chemical form Fractional absorption Reference... 

Fractional absorption values were taken directly or estimated from data presented in the cited references. 

Absorption of intramuscularly injected lanthanides (Durbin et al., 1956a) is greatly accelerated if they are administered as citrate complexes. However, the fractional absorption rate is still a function of the amount injected. One day after injection of < 1 jug of the lanthanide citrates, 0.95 had been absorbed 0.75 was absorbed in the first day if the amount of stable lanthanide administered was 1 to 5 jug. After 256 days, only 0.05 of the injected 152,154Eu plus 5 jug Eu remained unab-... 

Calcium Adequate intake (Table 3-1) in divided doses Absorption-predominantly active transport with some passive diffusion, fractional absorption 10-60%, fecal elimination for the unabsorbed and renal elimination for the absorbed calcium... 

Janghorbani et al. (58) fed isonitrogenous diets to 10 subjects for 12 days. Both an intrinsic label (chicken) and extrinsic labels were used. Zinc absorptions from an all-chicken diet and from a 50% chicken-50% soy isolate diet were equivalent. Solomons et al. (59) fed 5 or 10 subjects diets in which milk, soy isolate, and beef (or mixtures of these) were protein sources for the milk and/or soy diets, absorptions were similar "fractional" absorptions from beef bologna may have been higher than from soy bologna (Table IV). 

The information in Figure 14 was produced in the following way. The slope (or the Kurbatov coefficients shown in Table V) and position of the fractional absorption gdges in Figure 3 were used as the criteria of model fit. Kcd an< CdOH were used as the fitting parameters and all other parameters were held constant. Consequently, the intrinsic constants shown in Figure 14a represent best fit parameters and, given that all other surface and solution association constants are invariant, constitute a unique solution set for each adsorption density. 

Matsuda K, Yuasa H, Watanabe J (1998) Fractional absorption of L-carnitine after oral administration in rats Evaluation of absorption site and dose dependency. Biol Pharm Bull 21 752-755... 

In another study, the difference in fractional absorption between Ca from CCM and CaCOa was tesfed in 12 healthy adolescents (6 males and 6 females) aged 10-17 years using a 2-period crossover design (Miller et al., 1988). The average ( SEM) dietary Ca intake based on a food frequency quesfionnaire was 600.4 65.7 mg/day. The order of Ca supplementation for groups was randomized and for each treatment two tablets were ingested with a standardized breakfast. Each tablet contained... 

Hicks, P. D., and Abrams, S. A. (2006). Formula-fed full term infants have lower fractional absorption but greater total calcium absorption than human milk-fed infants. FASEB ]. 20, A991. 

Ackerman, S. A., and S. K. Cox, Aircraft Observations of Shortwave Fractional Absorptance of Non-Homogeneous Clouds, J. Appl. MeteoroL, 20, 1510-1515(1981). 

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