No description available.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1992. / Vita. Abstract. Includes bibliographical references (leaves 115-125). Also available via the Internet.

No description available.

This thesis relates to the mathematical modelling of biofilm in two primary areas: biofilm growth, and the effect of microbial immobilisation in biofilm on environmen- tal contaminant transport in the Earth's subsurface. For biofilm growth we construct a model based on polymer solution theory. Parameter estimates motivate a very different model from two published biofilm models also based on polymer solution theory. Analysis of ID solutions provides an expression for growth rate suitable for comparison with experiment. Stability analysis of spatial perturbations to a growing planar front reveals an interfacial instability mechanism similar to that found in a published theoretical study not based on a specific material model. We derive a stability criterion as a critical external nutrient boundary layer thickness, and for the travelling wave solution we identify the finite perturbation wavenumber selected by the instability. For environmental contaminant transport, we identify dissolution of organic phase contaminants and sorption of hydrocarbons onto solid grains as primary lim- itations on bioavailability. We build a pore scale model including both organic phase dissolution and micro- bial uptake and use it to parameterise pore scale Sherwood and Damkohler numbers with respect to pore Peclet number. We illustrate their relation to effective macro- scopic parameters for varying organic phase size relative to pore size. A simple intraparticle diffusion sorption model is extended by considering an external biofilm layer on the particles. A larger scale model considers contaminant transport in a ID flow through a bed of such particles. A physically reasonable pa- rameter regime is suggested, providing analytical solutions for breakthrough curves.

Bioavailability enhancement of poorly water soluble active pharmaceutical ingredients (API) is key for improving existing therapies and allowing for formulation of certain new chemical entities. The rate limiting step for absorption of these APIs is dependent on the dissolution rate and the APIs apparent solubility. Particle engineering processes such as evaporative precipitation into aqueous solution (EPAS) and spray freezing into liquid (SFL) were developed to enhance API dissolution and bioavailbality through the production of amorphous and nanoparticulate API. The morphology, primary API domain size and miscibility of particles produced by EPAS and SFL were investigated by several complementary and novel techniques. It was found that the SFL composition displayed amorphous character, a primary danazol particle size of 30 nm and was consistent with a solid solution. The EPAS composition was mostly amorphous with slight crystallinity, a primary danazol particle size of 500 nm and was consistent with a solid dispersion. The ability of the nanoparticulate and amorphous particles to supersaturate dispersions and how this impacts oral bioavailability was tested through in vitro and in vivo models. Through the use of a testing method for supersaturation, it was found that EPAS and SFL compositions achieve higher apparent solubilities when compared to the physical mixture and commercial Danocrine® capsules. This improvement in solubility allowed for more danazol to be available for absorption in vivo. Pulmonary delivery of SFL nanoparticulate itraconazole was evaluated for pharmacokinetic parameters and steady state trough levels compared to oral delivery of an SFL oral composition and the commercial product. Inhalation of ITZ compositions is an effective method of antifungal therapy for the treatment and prophylaxis of invasive fungal infections. High and sustained lung tissue concentrations are achieved via inhalation of an amorphous ITZ pulmonary composition while maintaining serum levels which are above the minimum lethal concentration for A. fumigatus. Histology, macrophage uptake and IL-12 induction was evaluated for aerosolized amorphous ITZ nanoparticles. Pulmonary administration of amorphous ITZ nanoparticles or excipient placebo does not cause inflammation or changes in alveolar and airway histology. Uptake of ITZ by alveolar and airway macrophages occurs following inhalation of an amorphous ITZ composition. / text

No description available.

This thesis focuses on the interactions between milk proteins (caseins) and tea catechins and the consequences of the interactions on the renneting properties and digestion of casein micelles as well as on the biological functionality of the mixture, as measured using intestinal cell models. The binding of epigallocatechin-gallate (EGCG) to casein micelles was quantified using HPLC and fluorescence quenching, and it was shown that a substantial amount of EGCG can be incorporated in the casein micelles. At concentrations < 2.5 mg/ml milk, most of the EGCG added to milk was associated with the caseins. The formation of EGCG-casein micelles complexes not only delayed the gelling point of milk, but they also affected the structure formation of the gels. EGCG is known to have antiproliferative activity on colon cancer cells. Although nanoencapsulation of EGCG in casein micelles may have some advantages, such as protecting this bioactive compound from degradation, it may also affect the bioavailability of EGCG. To test this hypothesis, the effect of nanoencapsulation of EGCG in casein micelles on the biological functionality of EGCG was tested by evaluating the cytotoxity and proliferation behaviour of HT-29 colon cancer cells. It was demonstrated that nanoencapsulation did not affect the bioefficacy of EGCG. Similar experiments were also carried out on rat colonic cells, a normal line and its cancerous tranformed line. For this study, nanoencapulated EGCG was subjected to in vitro digbefore absorption. The results showed that EGCG-casein binding did not affect the digestion of the milk proteins. In this case, the bioefficacy of EGCG was not diminished as well. In addition, studies on normal cell lines demonstrated the specific effect of EGCG on cancer cells, favoring normal cell survival whether EGCG was isolated or complexed with milk. These experiments bring further evidence that milk can be employed as an appropriate platform for the delivery of bioactive compounds.

No description available.

Two groups of soils were studied, the first being made up of twelve heavily fertilised representative soils from the European Community and the second containing fertilised and unfertilised soils for comparison. The first group demonstrate how the amount of plant available P was generally most closely related to soil P content, rather than soil chemical characteristics. However, the total adsorption capacity tends to decrease in the order moderately acid > calcareous > weakly acid. A very steep increase in solution P concentration above 60 percent saturation was observed and it was calculated that 15 to 30 years of cropping without further fertiliser P additions is required to bring some soils below this level. The second group of soils shows how long term P fertiliser additions cause accumulation of all forms of inorganic P. The comparison of a continuously fertilised soil to one which has had no P additions for three years, suggests that once soils of this type have been fertilised in excess of plant requirements, they can be cropped for several years without decreasing yield due to P deficiency. The aggregate separation indicates how selective erosion of small aggregates leads to increased loss of P in most cases. Mixing of aggregates demonstrated how some have a stronger ability to influence concentration than others and this was linked to their phosphate buffer capacity. Reducing conditions increased P release and this was linked to a combination of soil type, P content and cation release. Fertilisation has increased the available P and the ability to influence solution P most in the fraction at the greatest risk from erosion.

Thesis (M.S.)--Ohio State University, 2008. / Title from first page of PDF file. Includes bibliographical references (p. 72-86).