Phase contact ratio

The phase contact ratio for each concentration is calculated in two steps. First, the relative counting efficiency for each sample in both groups is calculated using the following equation ... 

The values of phase contact ratio are then plotted against the water sample concentration to give a curve where problem areas are readily apparent. Obviously a phase contact ratio of 1.00 at all concentrations represents ideal performance, showing perfect phase contact and equal counting efficiency for soluble tritium-labeled compounds at all concentrations regardless of partition coefficient. 

The following figures (1,2) are computer-fitted plots of phase contact ratio for several of the better commercially... 

FIGURE 1. Variation in Phase Contact Ratio For Various Solgel Scintillators... 

The phase contact ratios obtained should be accurate to about 0.5% at 95% confidence limits. The technique described here cancels out most of the common minor sources of error in liquid scintillation counting, for example ... 

Pyruvic acid is the simplest homologue of the a-keto acid, whose established procedures for synthesis are the dehydrative decarboxylation of tartaric acid and the hydrolysis of acetyl cyanide. On the other hand, vapor-phase contact oxidation of alkyl lactates to corresponding alkyl pyruvates using V2C - and MoOa-baseds mixed oxide catalysts has also been known [1-4]. Recently we found that pyruvic acid is obtained directly from a vapor-phase oxidative-dehydrogenation of lactic acid over iron phosphate catalysts with a P/Fe atomic ratio of 1.2 at a temperature around 230°C [5]. 

FIG. 20-39 Normalized free-energy difference between distributed (II) and nondistributed (I) states of the solid particles versus three-phase contact angle (collection at the interface is not considered). A negative free-energy difference implies that the distributed state is preferred over the nondistributed state. Note especially the significant effect of n, the ratio of the liquid droplet to solid-particle radius. [From Jacques, Hovarongkura, and Henry, Am. Inst. Chem. Eng. J., 23(1), 160 (1979).]... 

The types of equipment used, which range from stirred tanks and mixer-settlers to centrifugal contactors and various types of columns, affect both capital and operating costs [9]. In the decision to build a plant, the choice of the most suitable contactor for the specific situation is most important. In some systems, because of the chemistry and mass transfer rates involved, several alternative designs of contacting equipment are available. In the selection of a contactor, one must consider the capacity and stage requirements solvent type and residence time phase flow ratio physical properties direction of mass transfer phase dispersion and coalescence holdup kinetics equilibrium presence of solids overall performance and maintenance as a function of contactor complexity. This may appear very complicated, but with some experience, the choice is relatively simple. 

For the separation of the individual components, the partition between the phases is important. On contact of the mobile phase with the stationary phase, a component i of one phase is transferred to the other (Fig. 1-2), and this leads to different concentrations of this component in the two phases. The ratio of the concentrations is given by the equilibrium constant Kp... 

To obtain electron-spin densities it is necessary to distinguish Fermi contact shifts from the pseudocontact shifts for each compound. This may be done sometimes by comparing two series of complexes differing only in central metal ion, if it can be shown that the modes of spin delocalisation are identical but one member is magnetically isotropic. Alternatively, the shifts for a given nucleus in the paramagnetic species are compared in solution and in the solid. Fermi contact shifts are the same in fixed and mobile phases the ratio of pseudocontact shifts in fixed and mobile environments is related to the g-value anisotropies. (While theoretically generally applicable the method is restricted because of the wide lines obtained with solids.) Discrimination between... 

The volume of the inner aqueous solutiou relative to that of the organic solvent in W /0/Wn emulsion was found to be a critical parameter that determines the encapsulation efficiency of medicaments. For example, increasing the volume fractiou of the internal aqueous phase was found to lower the encapsulation efficiency of ovalbumin in PLA. This could be due to the increased probability of contact between the internal drug solution and the continuous extraction phase. Also, at low aqueous to organic phase volume ratios (<0.1 mL/mL), the encapsulation efficiencies of BSA, and an antigen within PLGA microspheres were found to be about 90%, and 100%, respectively. 

In interval of Ls / da ratio from 2 to 3 in tubular turbulent apparatus emulsions with comparable specific phase contact surface F and polydispersity kp are formed. 

---