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The putative peroxisome proliferator-activated receptor (PPAR) α ligand, conjugated linoleic acid (CLA) induced cytoplasmic lipid droplet (LD) formation in H4IIE rat hepatoma cells. Currently, the mechanism(s) by which CLA isomers affects hepatic LD formation is unclear. We have investigated the role of PPARα and fatty acid (FA) activation in the regulation of hepatic LD formation induced by CLA isomers [cis-9,trans-11 (c9,t11), trans-10,cis-12 (t10,c12)] and linoleic acid (LA) in an in vitro model of lipid accumulation. Dose response of c9,t11 and t10,c12 CLA isomers as well as LA in quiescent H4IIE cells was assessed by Oil Red O staining and subsequent quantification after 24 hours. LD formation was induced by the CLA isomers similar to LA in a dose-dependent manner. However, treatment with the acyl CoA synthetase (ACS) inhibitor, triacsin C, resulted in significantly reduced LD formation. A similar reduction in lipid accumulation was observed with the PPARα activator, Wy14643. Furthermore, CLA isomers promoted H4IIE viability at 60 µM but decreased viability at a higher dose of 180 µM. To further understand the role of PPARα in hepatic steatosis, we studied the level and phosphorylation of PPARα in livers of male lean and fa/fa Zucker rats fed either a control diet or fa/fa Zucker rats fed a CLA isomer (0.4% wt/wt c9,t11 or 0.4% wt/wt t10,c12) diet for 8 weeks. Immunoblotting results showed that only the t10,c12 CLA isomer significantly reduced phospho-PPARα S21 compared to the lean control (ln Ctl) and it was associated with a significant increase in the phosphorylation of p38 mitogen activated protein kinase (MAPK).These changes were not observed with the c9,t11 CLA isomer. Taken together, we have shown that CLA isomers directly induce LD formation in quiescent H4IIEs by activation of the lipid storage pathway which was significantly reduced by triacsin C or Wy14643. Also, we demonstrate for the first time that only the t10,c12 CLA isomer significantly reduced PPARα phosphorylation while it increased p38 MAPK phosphorylation. These results indicate that the anti-steatotic effects of the t10,c12 CLA isomer is associated with changes in PPARα phosphorylation and thereby its activity in a MAPK-independent manner.

Evaporation is used in the dairy industry to reduce the production costs of powder production (including milk powder) as it is more energy efficient to remove water by evaporation than by drying. There are significant economic reasons why gaining a greater understanding of the complex interactions occurring between the liquid and vapour phases in evaporators is advantageous. The multiphase flows in industrial dairy falling film evaporators were studied. Several computational fluid dynamic (CFD) models were created using Ansys CFX 10. Two case studies were chosen. The first case involved modelling the dispersed droplets that require separation from the water vapour evaporated from the feed of the evaporator. The CFD results were able to show that fouling was not caused by a lack of separation. The predicted separation agreed with experimental measurements. The atomisation process was found to be critical in the prediction of the separation. The atomisation process is not well understood and introduced the greatest error to the model. A plug flow assumption is currently used as a basis for the design the separators. The CFD solutions found no validity to this assumption. The second case study aimed to model and solve the distribution of the feed into the heat transfer tubes at the top of the falling film evaporators. The goal of this study was to be able to accurately predict wetting of the tubes. The volume of fluid (VOF) method using the continuum surface force method (CSF) to account for surface tension was chosen to model the system. The poor curvature estimate of the CSF method was found to produce parasitic currents that limited the stability of the solutions. Small VOF timesteps prevented the solver from diverging and the parasitic currents would oscillate the interface around the correct location. The small timesteps required significantly more computational power than was available and the model for the distribution process could not be solved. The CSF VOF method showed considerable promise, particularly because it can predict free surface topography without user input. There are still questions about numerical creeping of films, but the method was able to correctly predict several different surface tension and contact angle dominated film flows expected to be needed to accurately model the distribution of the falling film evaporator. Validated solutions of jet, meniscus, sessile, "overfall" and 3-D weir models were obtained and these agreed with published results in literature. A 2-D weir solution showed qualitative agreement with the expected form of the film. A 2-D hydraulic jump model without surface tension was created and agreed with experimental work in the literature to within 22%. The 3-D hydraulic jump solution only showed partial agreement with published experimental, the solutions were not mesh independent and not well converged so few conclusions can be drawn. The solutions of a rivulet model showed qualitative similarities with experimental work. The predicted wetting rate did not agree with values in the published literature because the spatial domain modelled was believed to be too narrow. An extended model of rivulet flow agreed with the idealised rivulet profile in literature and the predicted wetting rate agreed with some of the published literature. Again the solutions were not mesh independent so few conclusions can be confirmed.

Recently, considerable attention has been focused on the generation of nano- and micrometer scale multicomponent polymer particles with specifically tailored mechanical, electrical and optical properties. As only a few polymer-polymer pairs are miscible, the set of multicomponent polymer systems achievable by conventional methods, such as melt blending, is severely limited in property ranges. Therefore, researchers have been evaluating synthesis methods that can arbitrarily blend immiscible solvent pairs, thus expanding the range of properties that are practical. The generation of blended microparticles by evaporating a co-solvent from aerosol droplets containing two dissolved immiscible polymers in solution seems likely to exhibit a high degree of phase uniformity. A second important advantage of this technique is the formation of nano- and microscale particulates with very low impurities, which are not attainable through conventional solution techniques. When the timescale of solvent evaporation is lower than that of polymer diffusion and self-organization, phase separation is inhibited within the atto- to femto-liter volume of the droplet, and homogeneous blends of immiscible polymers can be produced. We have studied multicomponent polymer particles generated from highly monodisperse micrordroplets that were produced using a Vibrating Orifice Aerosol Generator (VOAG). The particles are characterized for both external and internal morphology along with homogeneity of the blends. Ultra-thin slices of polymer particles were characterized by a Scanning Electron Microscope (SEM), and the degree of uniformity was examined using an Electron Dispersive X-ray Analysis (EDAX). To further establish the homogeneity of the polymer blend microparticles, differential scanning calorimeter was used to measure the glass transition temperature of the microparticles obtained. A single glass transition temperature was obtained for these microparticles and hence the homogeneity of the blend was concluded. These results have its significance in the field of particulate encapsulation. Also, better control of the phase morphologies can be obtained by simply changing the solvent/solvents in the dilute solutions. Evaporation and drying of a binary droplet containing a solute and a solvent is a complicated phenomenon. Most of the present models do not consider convection in the droplet phase as solvent is usually water which is not very volatile. In considering highly volatile solvents the evaporation is very rapid. The surface of the droplet recedes inwards very fast and there is an inherent convective flow that is established inside the solution droplet. In this dissertation work, a model is developed that incorporates convection inside the droplet. The results obtained are compared to the size obtained from experimental results. The same model when used with an aqueous solution droplet predicted concentration profiles that are comparable to results obtained when convection was not taken into account. These results have significance for more rigorous modeling of binary and multicomponent droplet drying.

Dust capture for small coal particles (<2.5µm) can be improved if one takes advantage of electrostatic charges that resides on the surface of coal dust particles and on the surface of water spray droplets used to capture coal dust. Traditional dust capture methods that use water sprays are ineffective in capturing small dust particles since the motion of small dust particles is governed by electrostatic forces. If additives such as ionic surfactants could be added to water that would enhance the surface charge on water spray droplets, dust capture with water sprays could be improved. The results presented show that n-sodium octyl sulfate causes the greatest charge enhancement versus the longer chained n-sodium dodecyl sulfate and n-sodium octadecyl sulfate. This can be explained by considering the factors that lead to droplet charge enhancement. Those factors are the mass of surfactant ions at the droplet surface, and the diffusion rate of the surfactant ions from the bulk droplet to the surface of the droplet. Sodium octyl sulfate will have a faster diffusion rate to the droplet surface because of its relatively short length, and will also maximize the mass balance of surfactant ions at the drop surface.

Drop-on-demand (DOD) inkjet print-head has a major share of the market due to simplicity and feasibility of miniature system. The efficiency of droplet generation from DOD print-head is a result of several factors, include viscosity, surface tension, nozzle size, density, driving waveform (wave shape, frequency, and amplitude), etc. Key roles in the formation and behavior of liquid jets and drops combine three dimensionless groups: Reynolds number, Weber number and Ohnesorge number. These dimensionless groups provide some bounds to the “printability” of the liquid. Adequate understanding of these parameters is essential to improve the quality of droplets and provide guidelines for the process optimization. This thesis research describes the application of computational fluid dynamics (CFD) to simulate the creation and evolution process of droplet generation and transport of a highly viscous Newtonian fluid. The flow field is governed by unsteady Navier-Stokes equations. Volume of Fluid (VOF) model is used to solve this multi-phase (liquid-gas) problem.

Trace gases and aerosols, or suspended liquid and solid material in the atmosphere, have significant climatological and societal impacts; consequently, accurate representation of their contribution to atmospheric composition is vital to predicting climate change and informing policy actions. Sensitivity analysis allows scientists and environmental decision makers alike to ascertain the role a specific component of the very complex system that is the atmosphere of the Earth. Anthropogenic and natural emissions of gases and aerosol are transported by winds and interact with sunlight, allowing significant transformation before these species reach the end of their atmospheric life on land or in water. The adjoint-based sensitivity method assesses the relative importance of each emissions source to selected results of interest, including aerosol and cloud droplet concentration. In this work, the adjoint of a comprehensive inorganic aerosol thermodynamic equilibrium model was produced to improve the representativeness of regional and global chemical transport modeling. Furthermore, a global chemical transport model adjoint equipped with the adjoint of a cloud droplet activation parameterization was used to explore the footprint of emissions contributing to current and potential future cloud droplet concentrations, which impact the radiative balance of the earth. In future work, these sensitivity relationships can be exploited in optimization frameworks for assimilation of observations of the system, such as satellite-based or in situ measurements of aerosol or precursor trace gas concentrations.

The goal of this thesis is to study the ground or metastable state structure of nematic liquid crystal systems confined inside handled shapes such as a torus or double torus. We begin our work by introducing a new method to generate a toroidal droplet from a Newtonian liquid inside another, immiscible, Newtonian liquid. In this situation, a toroidal droplet is unstable and follows one of two routes in transforming into a spherical droplet: (i) its tube breaks in a way reminiscent to the breakup of a cylindrical jet, or (ii) its tube grows until it finally coalesces onto itself. However, to be able to probe the nematic structure, we need to address the issue of instabilities. This is done by replacing the outer liquid with a yield stress material, which ultimately leads to the stabilization of the toroidal droplet. Through the experimental investigation, we are able to establish the stabilization conditions. Finally, we generate and stabilize toroidal droplets with a nematic liquid crystal as the inner liquid and a yield stress material as the outer medium. Here we observe that in the ground state, the nematic liquid crystal exhibits an intriguing twisted structure irrespective of the aspect ratio of the torus. While there are no defects observed in a toroidal droplet case, two defects with -1 topological charge each emerge each time we increase the number of handles.

Hepatic lipase (HL) plays a pivotal role in the catabolism of apolipoprotein (apo)B-containing lipoproteins and high density lipoprotein (HDL) particles through its reported catalytic and non-catalytic extracellular functions. The current study tested the hypothesis that HL expression might impair formation and secretion of hepatic derived very low density lipoproteins (VLDL) and apoA-I (nascent HDL). Stable or transient expression of human HL (hHL) in McA-RH7777 cells resulted in decreased incorporation of [3H]glycerol into cell-associated and secreted (VLDL-associated) 3H-triacylglcyerol (TAG) relative to control cells. Stable expression of catalytically-inactive hHL (hHLSG) also resulted in decreased secretion of VLDL-associated 3H-TAG whereas cell-associated 3H-TAG levels were unchanged. Expression of hHL or hHLSG increased cell-associated 35S-apoB100 with relatively no change in secreted 35S-apoB100. Importantly, hHL or hHLSG expression resulted in reduced 3H-TAG associated with the microsomal lumen lipid droplets (LLD), and increased relative expression of ApoB and genes involved in lipogenesis and fatty acyl oxidation. Transient expression of hHL in HL-null primary hepatocytes, mediated by adenoviral gene transfer, resulted in decreased steady-state levels of cell-associated and secreted apoA-I and reduced rates of synthesis and secretion of 35S-apoA-I. HL-null hepatocytes exhibited increased levels of secreted 35S-apoA-I relative to wildtype hepatocytes while cell-associated 35S-apoA-I levels were normal. Transient expression of a hHL chimera (hHLmt), in which the C-terminus of hHL was replaced with mouse HL sequences, exerted an inhibitory effect on apoA-I production similar to that of hHL even though hHLmt was secreted less effectively than hHL with impaired exit from the endoplasmic reticulum (ER) as compared with hHL. In contrast, stable expression of hHL in McA-RH7777 cells resulted in a dose-dependent increase in cell-associated and secreted 35S-apoA-I levels. These studies demonstrate that hHL has an intracellular (but non-catalytic) role in reducing the content of the LLD and ultimately the buoyancy of secreted VLDL particles, and that the N-terminal sequences of ER-residing hHL directly or indirectly modulates the production and secretion of apoA-I (nascent HDL) from hepatocytes.