Internal and External Mixtures

More generally, an infinite number of intermediate cases are possible between the internal and external mixture models. To take into account variations in chemical composition from particle to particle, the particle size distribution function must be generalized, and for that purpose the size-composition probability den.sity fimetion has been introduced (Friedlander, 1970). Let r//V be the number of particles per unit volume of gas containing molar quuiititics... 

FIGURE 24.9 Mixing states of an aerosol—internal and external mixtures of (NILhSO, and soot. 

FIGURE 22.23 Mixing states of an aerosol-internal and external mixtures of (NH4)2S04 and soot. 

Clearly, such real-time, single-particle techniques have great promise in terms of elucidating the chemical nature of different species in tropospheric particles and determining whether they exist as internal or external mixtures. 

Eprinomectin is derived from the natural product abamectin by conversion of the 4 -hydroxy group to the 4 -cp -A-acetyl substituent. Like abamectin, eprinomectin is a mixture of two active constituents that contain more than 90% 4 -deoxy-4 -(ep/-acetylamino)avermectin B a and less than 10% 4 -deoxy-4 - epi-acetylaminojavermectin Bib. It is indicated for treatment of internal and external parasites in beef and dairy cattle at a dosage of 0.5 mg/kg bw and is applied along the midline of the animal s back (61). 

Chan and Lee [24] assumed that a reaction equilibrium existed in both the internal and external continuous phases. They also incorporated the overall mass transfer resistance in their model as weU as accounting for leakage of the internal phase into the external phase as did Borwankar et al. [25], Liu and Liu [26], and Boyadzhiev et al. [27]. The reversible model was later extended by Baird et al. [22] to predict the extraction rate for multicomponent systems. A comparison study of the advanced front model and the reversible reaction model for multicomponent systems undertaken by Wang and Bunge [28] found the latter to be signihcantly better for mixtures of organic acids. 

FIGURE 24.10 Total extinction, scattering, and absorption coefficients for internal versus external mixtures of soot and (NH4)2S04. 

Mixture of internal and external lubricants containing montan waxes 0.75 0.75... 

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