published_or_final_version / Medical Sciences / Master / Master of Medical Sciences

published_or_final_version / abstract / toc / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / abstract / toc / Paediatrics and Adolescent Medicine / Master / Master of Philosophy

In spite of abundant water resources, world is suffering from the scarcity of usable water. Seawater Reverse Osmosis (SWRO) desalination technology using polymeric membranes has been recognized as a key solution to water scarcity problem. However, economic sustainability of this advanced technology is adversely impacted by the membrane fouling problem. Fouling of RO membranes is a highly studied phenomenon. However, literature is found to be lacking a detailed study on kinetic and dynamic aspects of SWRO membrane fouling. The factors that impact the fouling dynamics, i.e., pretreatment and water quality were also not adequately studied at full–scale of operation. Our experimental protocol was designed to systematically explore these fouling aspects with the objective to improve the understanding of SWRO membrane fouling mechanisms. An approach with multiple analytical techniques was developed for fouling characterization. In addition to the fouling layer characterization, feed water quality was also analysed to assess its fouling potential. Study of SWRO membrane fouling dynamics and kinetics revealed variations in relative abundance of chemical and microbial constituents of the fouling layer, over operating time. Aromatic substances, most likely humic–like substances, were observed at relatively high abundance in the initial fouling layer, followed by progressive increase in relative abundances of proteins and polysaccharides. Microbial population grown on all membranes was dominated by specific groups/species belonging to different classes of Proteobacteria phylum; however, similar to abiotic foulant, their relative abundance also changed with the biofilm age and with the position of membrane element in RO vessel. Our results demonstrated that source water quality can significantly impact the RO membrane fouling scenarios. Moreover, the major role of chlorination in the SWRO membrane fouling was highlighted. It was found that intermittent mode of chlorination is better than continuous mode of chlorination of seawater, as anti–biofouling strategy. It was also confirmed that significant biofilm development was inevitable even with the use of chlorine to disinfect SWRO membranes. Our findings on the dynamic patterns of SWRO membrane fouling should help in further elaborating research projects focusing on the development of better strategies to minimize this troublesome phenomenon.

No description available.

In cell biology and chemistry, total internal reflection microscopy (TIRFM) has proven to be a useful technique that allows the probing of cellular processes with high-signal-to-noise ratio imaging. However, samples on solid substrates limit the accessibility to probe processes on extracellular membrane surface closest to the microscope objective. Colloidal crystals provide a porous alternative to the traditional solid substrates. Thin crystals exhibit optical properties similar to that of a fused silica coverslip allowing for TIRFM in the same manner as with a typical coverslip as demonstrated by the observance of Chinese hamster ovary cells with fluorescently labeled receptors on both types of substrates. Accessibility of the cell membrane closest to the substrate and the ability to probe fluorophore orientation information was observed by the binding of TIPP-cy5 to the human delta opioid receptor.

Fluidic lenses have been developed for ophthalmic applications. The lenses use a pressure differential to deform a membrane, which separates two fluids with different indexes of refraction. The change in membrane shape creates changes in the optical wavefront. By utilizing different boundary conditions on the membrane, the progression of the membrane shape can be controlled. Specifically, a circular restraint is used to produce optical power, whereas a rectangular restraint is used to produce a combination of power and astigmatism. These lenses are analyzed for dominant properties and wavefront quality. By combining 2 rectangular restraint lenses at 45° and a circular restraint lens, both orthogonal second order Zernike astigmatisms as well as second order power can be independently controlled. This combination can also be described as independent control of ophthalmic cylinder, cylinder axis, and power, which is required to create a basic phoropter. A fluidic phoropter is demonstrated and analyzed in this manuscript.

The title of this thesis requires some explanation. The term "microcapsules" is a coinage of my own. The Concise Oxford Dictionary gives several definitions of "capsule" (from Latin capsa, a case). Two of these definitions are relevant to my usage: a capsule is a "membranous envelope (Physiol.)" or a "gelatine envelope enclosing pill (Med.)". A "semipermeable aqueous microcapsule" is therefore an envelope of semipermeable membrane enclosing a very small aqueous compartment. At this point it may be useful to discuss also the terms "membrane" and "semipermeable". [...]

The aim of this study was to test the application of an in situ–formed synthetic polyethylene glycol (PEG) as a biodegradable membrane with a variety of graft materials and hyperbaric oxygen (HBO) for enhanced bone regeneration. Critical-sized rabbit calvarial defects were created in bilateral parietal bones. Group 1 served as a control with unfilled defects, Group 2 had defects filled with morcelized autogenous bone, and Group 3 had defects filled with biphasic calcium phosphate. One defect was protected PEG membrane and half the animals were subjected to HBOT treatment. The unsupported membrane didn’t produce the desired bone regeneration in the unfilled and bone grafted groups. HBO didn't ameliorate the bone grafted or ceramic filled defects over the 6-week time period. Caution is recommended with the membrane over unsupported defects. Future assessments with HBO should be completed at the 12-week time point.

No description available.