The concept of controlled release has attracted increasing attention
over the last two decades, with the applications of this technology
proliferating in diverse fields in- cluding medicine, agriculture and
biotechnology. Research and developmental efforts related to controlled
release are multiplying in both industry and academia. The reason for
this phenomenal growth is obvious. The use of a variety of biologically
active agents, such as drugs, fertilizers and pesticides, has become an
integral part of modern society. Along with the use of these reagents
has evolved an awareness that their uncontrolled application almost
inevitably induces harmful effects on the health of humans and their
surrounding environments. To eliminate or minimize these harmful effects
necessitates the controlled release of these chemicals. Moreover, the
controlled release of substances, not usually considered toxic or
hazardous, e.g., some catalysts and nutrients, can enhance their
effectiveness. The number and variety of controlled release systems,
differing in their physical and chemical makeup, are increasing rapidly.
Proliferation almost always demands correlation, generalization and
unification; it requires both the development of underlying theories of
their behavior and the mechanistic interpretation of their performance.
This, in turn, requires a statistical and mathematical (quantitative)
treatment of the scientific information and technical data pertaining to
them. A quantitative treatment can also facilitate the formulation of
procedures for computer-aided design of these systems through a priori
prediction of their per- formance for a variety of design parameters.
