The main objective of this research was to better understand, predict and control of the periodic precipitation process and to apply such programmed periodic precipitation to the design of a pulsatile delivery system. In the first part of this study, a generalized model taking into account both nucleation, particle growth, and ripening process was refined and solved under various new concentration boundary conditions not previously investigated. The results clearly delineate the key differences between boundary conditions of infinite versus finite supply of inner electrolyte. When the inner electrolyte boundary concentration was allowed to increase exponentially with time, equidistant periodic precipitation was predicted and subsequently confirmed experimentally. In addition, the effects of product solubility and reaction rate constant were also shown to be important in determining the band number and band spacing. In the second part of this study, the effects of gel crosslinking and gel charge density on the periodic precipitation were investigated. The results indicate that by increasing either the gel crosslinking or decreasing the gel charge density will reduce the diffusion rate of the reactants resulting in closely spaced bands. In addition, a new and improved rotating disk method for characterizing polyelectrolyte gels with ion-penetrable soft surfaces has been established by taking into account the effect of surface conductivity which is usually ignored for ion-impenetrable hard surfaces. In the third part of this work, periodic precipitation formed in multi-component systems has been shown to be governed by a heterogeneous nucleation mechanism. Using this approach, periodic precipitation of an insulin mimetic compound VO2+ in gelatin gel, which cannot form alone in a single reaction system, was induced by the periodic precipitation of Mg(OH)2 in a multi-component system. Pulsatile release of VO2+ from the resulting multi-layered structure of VO(OH)2 via a surface erosion mechanism was subsequently demonstrated.

The main objective of this research was to better understand, predict and control of the periodic precipitation process and to apply such programmed periodic precipitation to the design of a pulsatile delivery system. In the first part of this study, a generalized model taking into account both nucleation, particle growth, and ripening process was refined and solved under various new concentration boundary conditions not previously investigated. The results clearly delineate the key differences between boundary conditions of infinite versus finite supply of inner electrolyte. When the inner electrolyte boundary concentration was allowed to increase exponentially with time, equidistant periodic precipitation was predicted and subsequently confirmed experimentally. In addition, the effects of product solubility and reaction rate constant were also shown to be important in determining the band number and band spacing. In the second part of this study, the effects of gel crosslinking and gel charge density on the periodic precipitation were investigated. The results indicate that by increasing either the gel crosslinking or decreasing the gel charge density will reduce the diffusion rate of the reactants resulting in closely spaced bands. In addition, a new and improved rotating disk method for characterizing polyelectrolyte gels with ion-penetrable soft surfaces has been established by taking into account the effect of surface conductivity which is usually ignored for ion-impenetrable hard surfaces. In the third part of this work, periodic precipitation formed in multi-component systems has been shown to be governed by a heterogeneous nucleation mechanism. Using this approach, periodic precipitation of an insulin mimetic compound VO2+ in gelatin gel, which cannot form alone in a single reaction system, was induced by the periodic precipitation of Mg(OH)2 in a multi-component system. Pulsatile release of VO2+ from the resulting multi-layered structure of VO(OH)2 via a surface erosion mechanism was subsequently demonstrated.

No description available.

No description available.

Hyperkalemic periodic paralysis (HyperKPP) is an autosomal dominant human skeletal muscle channelopathy that causes periods of myotonic discharge and periodic paralysis due to defective Nav1.4 sodium channels. Patients are asymptomatic at birth, attacks become short and frequent during childhood, and more severe during adolescence. Since the Nav1.4 content in the cell membrane is relatively constant during childhood, it was hypothesized that some symptoms start with the defective Nav1.4 channels, while other symptoms start after some changes occur in gene expression affecting other membrane channel content and/or activity. To test the hypothesis, the contractile characteristics of EDL and soleus muscles from HyperKPP mice from the age of 0.5 to 12 months were tested in vitro. For both EDL and soleus, contractile defects, including low force generation, instability and large unstimulated force were observed by two weeks of age. With aging, the defects did not worsen, but muscles actually showed some improvement. Considering that Nav1.4 protein content reaches maximum at three weeks of age, the data suggests that HyperKPP symptoms are solely due to the defective Nav1.4 channels.

An introduction to periodic orbit techniques for deterministic dynamical systems is presented. The Farey map is considered as examples of intermittency in one-dimensional maps. The effect of intermittency on the Markov partition is considered. The Gauss map is shown to be related to the farey map by a simple transformation of trajectories. A method of calculating periodic orbits in the thermostated Lorentz gas is derived. This method relies on minimising the action from the Hamiltonian description of the Lorentz gas, as well as the construction of a generating partition of the phase space. This method is employed to examine a range of bifurcation processes in the Lorentz gas. A novel construction of the Sinai billiard is performed by using symmetry arguments to reduce two particles in a hard walled box to the square Sinai billiard. Infinite families of periodic orbits are found, even at the lowest order, due to the intermittency of the system. The contribution of these orbits is examined and found to be tractable at the lowest order. The number of orbits grows too quickly for consideration of any other terms in the periodic orbit expansion. A simple stochastic model for the diffusion in the Lorentz gas was constructed. The model produced a diffusion coefficient that was a remarkably good fit to more precise numerical calculations. This is a significant improvement to the Machta-Zwanzig approximation for the diffusion coefficient. We outline a general approach to constructing stochastic models of deterministic dynamical systems. This method should allow for calculations to be performed in more complicated systems.

Thesis--Copenhagen. / "Litteraturfortegnelse": p. [93]-94.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 81-91). Also available on the Internet.

Thesis (Ph. D.)--University of Missouri-Columbia, 1998. / Typescript. Vita. Includes bibliographical references (leaves 81-91). Also available on the Internet.

Thesis--Copenhagen. / "Litteraturfortegnelse": p. [93]-94.