Generalized multicompartment

This assumption is essentially the same for all PK models described in this chapter. See Section 10.7.1.3 for the details regarding this assumption. Unlike the standard one- and two-compartment models, where the equations are written for elimination only from the central compartment (compartment 1), elimination can occur from any one or any combination of model compartments for the generalized multicompartment equations. 

Each of the exponential decay terms in the generalized multicompartment models represent a distinct phase or change in shape of the plasma concentration versus time curve. The extra (n+l) exponential term for first-order absorption always has the absorption rate constant (ka) in the exponent, and always represents an absorption phase. The exponential term with the smallest rate constant (A ) always represents the elimination phase, and this rate constant always represents the elimination rate constant and always equals the terminal line slope m= — A J. All other exponential terms represent distinct distribution phases caused by the different rates of distribution to different tissue compartments. 

Generalized Multicompartment Model until Instantaneous or First-Order Absorption... 

Generalized multicompartment models provide a means of representing highly complex PK situations with relatively simple plasma concentration equations. 

What are some advantages and disadvantages associated with the use of generalized multicompartment models ... 

The research published in this book uses the presently most comprehensive multicompartment model, the first which comprises a coupled atmosphere-ocean general circulation model (GCM). GCMs are the state-of-the-art tools used in climate research. The study is on the marine and total environmental distribution and fate of two chemicals, an obsolete pesticide (DDT) and an emerging contaminant (perflu-orinated compound) and contains the first description of a whole historic cycle of an anthropogenic substance, i.e. from the introduction into the environment until its fading beyond phase-out. 

Heat Treatment Heat treatment can be divided into two types, treatment of fluidizable solids and treatment of large, usually metallic objects in a fluid bed. The former is generally accomplished in multicompartment units to conserve heat (Fig. 17-28). The heat treatment of large metallic objects is accomplishecTin long, narrow heated beds. The objects are conveyed through the beds by an overhead conveyor system. Fluid beds are used because of the high heat-transfer rate and uniform temperature. See Reindl, Fluid Bed Technology, American Society for Metals, Cincinnati, Sept. 23, 1981 Fennell, Ind. Heat., 48, 9, 36 (September 1981). 

Figure 8. Multicompartment monolayer trough for manipulation of films on the surface. Schematic provided by Dr. S. J. V enty of General Electric Co. and reprinted from Journal of the American Chemical Society 1979, 101, 1. Copyright 1979, American Chemical Society.

Heat Treatment Heat treatment can be divided into two types, treatment of fluidizable solids and treatment of large, usually metallic objects in a fluid bed. The former is generally accomplished in multicompartment units to conserve heat (Fig. 17-27). The heat treatment of large metallic objects is accomplished in long, narrow heated beds. 

Hi) Salt from sea water Another principal application of electrodialysis is the production of common salt from sea water. In the manufacture of salt from this source, generally sea water is first filtered and then warmed with waste heat. Next, this water is slowly passed through the depletion compartments of the multicompartment electrodialysis equipment. Concentration of solids reaches about 20% by weight in the brine collecting in the enrichment compartments. Further processing of this concentrated brine by evaporation yields the salt in solid crystalline state. 

It is not unusual for PK research articles to report model parameters for three-, four-, or five-compartment models for some drugs. If the multicompartment model parameters are known for a drug, then the plasma concentration at any time can be predicted by the equations in Table 10.2. Determining the time at which the plasma concentration reaches a particular value is generally a very laborious trial-and-error calculation, since the concentration equation contains multiple exponential decay terms. An exception occurs for plasma concentration Cf) values at long enough times to be located on the terminal line. For this special case, the time at which a particular plasma concentration is reached is given by... 

Estimation of multicompartment model parameters from measured plasma samples is typically performed utilizing specialized PK software. The general methods are very similar to that used for the previous models. 

More subtle chemistry is required when the selective placement of receptees involves competing receptees of the same kind. Metal atoms, O2 molecules and substrate molecules are generally rather different and require quite different receptors, a situation favoring selective binding. We will now consider the situation where, in a heterometallic complex with a multicompartment ligand, it is important to have the different metal ions occupy specific sites. Ambitions for certain magnetic coupling patterns in polynuclear metal complexes illustrate this situation. ... 

Janus particles have equal phase-separated domains which can be located either in the core or in the corona (if present), whereas multicomparOnent particles can be generally defined as a colloidal structures which are composed of multiple phase-separated domains in the core. Particles with patches on the surface are called patchy particles and have potential applications in electronics and targeted drug delivery. Furthermore, Janus or multicompartment particles with patches on the surface can be called patchy-Janus particles or patchy-multicompartment particles, respectively. 

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