archives@tulane.edu / Amniotic fluid (AF) and amniotic membrane (AM) have been identified as potential new sources of stem cells. While numerous studies have confirmed the presence of mesenchymal stem cells (MSCs) in AM cells, limited research exists regarding full-term AF cells. The goal of this research was to assess the ability to process full-term AF and AM and characterize cell populations isolated from these sources. Specifically, their MSC capability was explored by studying their stemness marker expression, adipogenic and osteogenic differentiation potential, and ability to proliferate and form colonies. AF and AM samples were obtained from consenting donors who underwent elected Cesarean sections. Flow cytometry analysis showed positive expression of MSC markers in AF and AM cells. AF and AM cells exhibited proliferative and colony-forming capabilities. AM cells differentiated into mature adipocytes, whereas AF cells showed morphological changes but not mature differentiation. These findings confirm the feasibility of collecting and processing AF and AM samples at the time of delivery for stem cells. Although there is variability among AF and AM samples in terms of proliferative and colony-forming capabilities, as well as AM cells differentiation potential. Further research and optimization of methods is needed to better characterize the cell types, including MSCs, present in AF and AM. / 1 / Ann Marie Barfield

The avian and mammalian tectorial membranes both contain two non-collagenous glycoproteins, a- and ß-tectorin. To determine whether variations in the primary sequence of the chick and mouse a-tectorins account for differences in subunit composition and matrix structure of the tectorial membranes in these two species, the cDNA for chick atectorin was cloned and sequenced. The derived amino acid sequence was found to have 73% identity with mouse a-tectorin, suggesting that the tectorins are highly conserved proteins. The central region of chick a-tectorin contains fewer potential N-glycosylation sites than that of mouse a-tectorin and is cleaved at two additional sites. The extra glycosylation sites in the mouse sequence may help occlude sites of proteolytic attack. In situ hybridisation and northern blot analysis indicate that the spatial and temporal patterns of chick a- and ß-tectorin mRNA expression in the inner ear are different, suggesting that the two tectorins may each form homomeric filaments. Early functional recovery in the chicken after sound damage has been attributed to the rapid regeneration of the tectorial membrane. In situ hybridisation indicates that both aand ß-tectorin mRNAs are upregulated in the sound damaged basilar papilla. The regenerated tectorial membrane contains both a and ß-tectorin proteins. In order to understand how the tectorin genes are regulated during development and regeneration, the upstream non-coding region of the ß-tectorin genes from mouse and chicken were compared in an attempt to identify potential regulatory elements. DNA sequence alignments of the chick and mouse ß-tectorin upstream sequence show low identity, suggesting that the chick and mouse ß-tectorin promoters have not remained functionally conserved throughout evolution.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2007. / Includes bibliographical references (leaves 74-82). Also available in electronic version.

Thesis (M. Phil.)--Hong Kong University of Science and Technology, 2004. / Includes bibliographical references (leaves 93-102). Also available in electronic version. Access restricted to campus users.

Thesis (Ph. D.)--McMaster University, 2003. / Adviser: D. W. Andrews. Includes bibliographical references. Also available via World Wide Web.

Thesis (MTech (Chemical Engineering))--Cape Peninsula University of Technology, 2006 / A protocol already exists for fabrication of a capillary membrane having an internal ultrafiltration skin supported by a finger-like pore structure in the external capillary wall (Jacobs and Leukes, 1996; Jacobs and Sanderson, 1997). These membranes have been produced at the Institute of Polymer Science, University of Stellenbosch, South Africa. Two major applications emerged from the development of these internally skinned membranes. One application was in the production of potable water by Ultra-filtration (UF) from sources containing coloured water. A second application was in the immobilization of a white rot fungus in a ."gradostat" membrane bioreactor. Here a nutrient gradient through the membrane wall and fungal mat can be established and manipulated in order to stimulate continuous production of secondary metabolites (extra-cellular enzymes). These enzymes are useful in the degradation of polycyclic aromatic compounds, notably PCB species in contaminated water and soils (Jacobs and Sanderson, 1997). Two objectives emerged from experiences with the above applications. The first objective was to improve membrane performance in UF applications. In this case a reduction was sought in trans-membrane pressure differential required to attain a desired flux without sacrificing rejection. The pressure required for a given desired flux across a membrane depends on the resistance of the membrane skin layer and of its supporting sub-layer which together comprises the capillary wall and defmes its overall structure. If any of these resistances could be reduced, the overall resistance to transport of water would be reduced. Then it would be possible to operate the membrane at lower trans-membrane pressure differences. On the other hand, operation with higher pressure would also increase flux but require a thicker capillary wall to resist this pressure. In the attempt to optimise these properties of the capillary membrane, capillary membranes produced in the study reported here were tested to find the relationship of flux performance with the structures that resulted from varying key parameters affecting structure and integrity. The objective in the case of immobilizing fungi in membrane bioreactor applications was to attain thicker walls thus providing better support for the fungal mass. The internally skinned capillary membrane has finger-like microvoids that start next to the UF skin layer and extend across the capillary membrane wall and open at the external membrane periphery, giving an ideal structure for retaining the fungal biomass. The idea of a membrane with this type of morphology to immobilize white rot fungi was to anchor the growing fungus within these microvoids which imitate the natural environment in which these organisms live, that is, in the fibrous structure of decaying wood. The requirement to inoculate the microvoids with fungal spores (reproductive cells), implies that they need to be accessible from the outside, requiring a membrane wall that is externally unskinned. In the formation ofthe capillary membrane the processes of formation of the porous UP skin and the finger-like microvoids are mainly governed by diffusion of solvent out of a polymer dope (gel phase) and of non-solvent into the dope phase. Such exchanges are of primary importance between the bore fluid (containing non-solvent) and dope (containing solvent) or between the external spinning bath (high in solvent content) and dope. Diffusion effects also occur between the nascent pore voids and the precipitating polymer matrix. There are also expected to be some convection effects due to shear between the bore fluid and the moving dope gel phase and due to shrinkage ofthe gel phase. The variables selected for experimentation m the study reported here were: the dope extrusion rate (DER); dope composition (viscosity effects); bore fluid flow rate (BFF); bore fluid composition and wall thickness and diameter effects (determined largely by spinneret dimensions). Each of these has an expected effect on membrane structure and its resulting performance. Most were varied over narrow ranges indicated in the literature and by experience to be effective and critical. In addition, the effects of altering the walI thickness were investigated by using two different spinneret sizes. The external spinning bath composition (solvent content) was reported in the literature to be a particularly important parameter in the formation of externally unskinned membranes. Maintaining a high content of solvent in the external spinning bath could prevent skin formation. Too high a solvent content could, however, prevent phase transition and lead to later precipitation ofa dense skin on contact with the non-solvent in the later (humidification and rinsing) steps in the fmishing of the capillary membrane product. The external bath composition was therefore varied so as to find the bath composition that would match the cloud point for the polymer dope employed. As expected, the thickness of the membranes increased with DER increase. However, it was found that there is a critical wall thickness where an external skin layer is formed as a result of increasing the DER. A certain volumetric ratio ofDER to BFF (1,5:1 for this study) was therefore maintained in order to produce externally unskinned membranes. This shows that although the final membrane structure is detennined by the casting dope formulation, the fabrication protocol plays an equally important role in controlling structural properties and perfonnance. There was no significant change with the membrane thickness as a result of changing BFF but the voids became longer and more in number as the BFF was increased. Too high solvent content (99% NMP in this study) resulted in an external skin layer being formed. According to Smolders et.al. (1992), when the solvent content in the external spinning bath is too high, the polymer at the surface of the newly fonned membrane slowly dissolves in the external spinning bath re-forming a dope-like solution. When the newly formed membrane passes through the humidifier, the dope-like solution solidifies to form an external skin. At the same instance, too low solvent (93% for this study) resulted in external skin being fonned. Externally unskinned membranes were formed at 94 and 96% NMP bath composition. The use of a small spinneret resulted in very thin walled externally unskinned membranes.

Membrane distillation (MD) is an emerging thermal separation technology which proved its efficiency in desalination of highly saline waters, including seawater, brines and impaired process waters. In a long-term prospective, MD can reinforce sustainability of the clean water production and mitigate the water-energy stress caused by lacking suitable freshwater recourses. However, just like in any other membrane separation process, MD membrane is susceptible to biofouling which presents a significant challenge by substantially reducing its performance and deteriorating permeate quality. This study evaluated different cleaning methods aimed at controlling biofilm development on a surface of hydrophobic MD membrane in a direct contact MD (DCMD) process fed by the Red Sea water. This was achieved by applying physical (hydraulic) cleaning and chemical cleanings with a range of chemicals utilized in membrane separation processes including citric acid (mineral acid), ethylenediaminetetraacetic acid (EDTA, metal-chelating agent) and sodium hypochlorite (NaOCl, oxidant). Flux recovery and changes in biofilm morphology, including its thickness and structure as well as microbial and extracellular polymeric substances (EPS) contents before and after cleanings have been analyzed to elucidate cleaning mechanisms and suggest effective strategies of biofilm removal. The results showed that 0.3% EDTA exhibited the best cleaning performance resulting in the highest permeate flux recovery (93%), followed by 0.3% NaOCl (89%), 3% citric acid (76%), and hydraulic (66%) cleanings. Application of EDTA and NaOCl has also resulted in the lowest number of bacterial cells and substantial reduction of the peak intensities caused by protein-like compounds and tyrosine-containing proteins present on the membrane surface after its treamtent. The observed trends are in a good correlation with the optical coherence tomography (OCT) observations which revealed substation changes in biofilm morphology leading to a significant reduction of biofilm thickness which followed the order of hydraulic cleaning < citric acid cleaning < NaOCl cleaning < EDTA cleaning. This study suggests that selection of an appropriate cleaning type and formulation is critical for achieving sustainable MD plant operations, both technically and economically.

Membrane biofouling is a common occurrence in water treatment plants that utilize reverse osmosis (RO). As bacteria and biofilm material build up on the membrane surface, it becomes more difficult for clean water to permeate through the membrane, and more pressure is required to produce the same amount of water. When pressures become critically high, membranes must be cleaned. This process is expensive in terms of chemical cost, labor, and downtime. Even after membranes have been cleaned, they can re-foul quickly if the cleaning did not effectively remove the biofilm. The water treatment plant in Dunedin, FL, which uses RO for treating groundwater, has experienced membrane biofouling since it began operation in 1992. Without the means to systematically evaluate a multitude of cleaning strategies on the bench scale, cleaning optimization must be conducted on the production skid level, which restricts the evaluation of alternative protocols. This problem is typical for many RO plants. The objectives of this project are: (1) using a multi-level and systematic approach, develop cleaning strategies for biofouled membranes that will lead to improved cleaning and decreased operational costs; (2) develop other cleaning strategies that will add to the scientific knowledge base; (3) quantify the effects of improved protocols; and (4) determine the policy implications of developed protocols in terms of cost suitability to Dunedin and elsewhere in Florida. This project consists of three phases, with phases progressively more similar to the water production environment. In the first phase, a series of bench tests were performed in the laboratory. Fouled membrane swatches were soaked and agitated in different cleaning solutions for different lengths of time, at different temperatures and pH. Protein and carbohydrate assays were then performed on both the cleaning solution and the membrane swatch to determine which conditions yield most complete removal of protein and carbohydrate from the membrane surface. Results indicate that carbohydrate removal does not appear to depend strongly on pH or temperature. Protein removal increases with increasing pH and is slightly greater at higher temperatures. The second phase of testing employed a 4"x6" stainless steel flat-sheet module in which cleanings were performed under different conditions to document corresponding changes in water flux and salt rejection. Operational parameters were based on pertinent literature and optimization results from Phase 1. Results indicate that water flux increases in response to cleaning at increasing pHs and increasing temperatures with best performances occuring after 30 minutes of cleaning. Salt rejection appears to decrease with pH. The most effective cleaning protocols, determined through trials in Phases 1 and 2, were put to the test again in Phase 3 where cleanings were performed on a specially constructed single-element cleaning system (for 8.5" x 40" elements), designed to clean a membrane element in isolation. This phase also served as final verification of new cleaning protocols before implementation on the production scale. Results from this phase were inconclusive due to mechanical problems. A multi-level, systematic cleaning evaluation leads to better understanding of the dependence of biofilm material removal and membrane performance on critical factors such as temperature, pH, time of cleaning, and chemical dose, which results in improved cleaning protocols and ultimately cost savings to RO water utilities such as Dunedin.

Macromolecular components, including protein and polysaccharides, are viewed as one type of major foulants in the complex feed membrane filtration systems such as membrane bioreactor (MBR). In this thesis, the mechanisms of macromolecular fouling including protein and polysaccharide in the complex feed solution are explored by using Bovine serum albumin (BSA) and alginate as model solution. During the filtration of BSA and washed yeast with 0.22 ????m PVDF membrane, it was found that the critical flux of mixture solution was controlled by washed yeast concentration while the existence of BSA significantly changed the cake reversibility of much larger particles. The fouling mechanisms of alginate, as a model polysaccharide solution, were investigated both in dead end and crossflow membrane filtration. In the dead end experiments, it was found that the cake model appears to fit the entire range of the ultrafiltration data while the consecutive standard pore blocking model and cake model are more applicable to microfiltration membranes. The alginate was featured with high specific cake resistance and low compressibility despite some variations between different membranes. The specific cake resistance ( c ) is similar to c of BSA and actual extracellular polymer substance (EPS) in MBR systems reported in the literature, and higher than that of many colloidal particles. In a system contained alginate-particles mixture, it was found that the existence of alginate dramatically increased the cake specific resistance and decreased the cake compressibility. The fouling mechanism of alginate was also studied using long term cross flow filtration under subcritical flux. A two-stage TMP profile similar to that typically observed in MBR was obtained, confirming the important role of EPS during membrane fouling in MBR. In addition to adsorption, trace deposition of alginate also contributed to the initial slow TMP increase during the subcritical filtration. TMP increase during the long-term filtration was found not only due to the increase of the amount of deposition, but also the increase of specific cake resistance. A combined standard pore blocking and cake filtration model, using a critical pore size for the transition time determination, was developed and fit the experimental results well.

Macromolecular components, including protein and polysaccharides, are viewed as one type of major foulants in the complex feed membrane filtration systems such as membrane bioreactor (MBR). In this thesis, the mechanisms of macromolecular fouling including protein and polysaccharide in the complex feed solution are explored by using Bovine serum albumin (BSA) and alginate as model solution. During the filtration of BSA and washed yeast with 0.22 ????m PVDF membrane, it was found that the critical flux of mixture solution was controlled by washed yeast concentration while the existence of BSA significantly changed the cake reversibility of much larger particles. The fouling mechanisms of alginate, as a model polysaccharide solution, were investigated both in dead end and crossflow membrane filtration. In the dead end experiments, it was found that the cake model appears to fit the entire range of the ultrafiltration data while the consecutive standard pore blocking model and cake model are more applicable to microfiltration membranes. The alginate was featured with high specific cake resistance and low compressibility despite some variations between different membranes. The specific cake resistance ( c ) is similar to c of BSA and actual extracellular polymer substance (EPS) in MBR systems reported in the literature, and higher than that of many colloidal particles. In a system contained alginate-particles mixture, it was found that the existence of alginate dramatically increased the cake specific resistance and decreased the cake compressibility. The fouling mechanism of alginate was also studied using long term cross flow filtration under subcritical flux. A two-stage TMP profile similar to that typically observed in MBR was obtained, confirming the important role of EPS during membrane fouling in MBR. In addition to adsorption, trace deposition of alginate also contributed to the initial slow TMP increase during the subcritical filtration. TMP increase during the long-term filtration was found not only due to the increase of the amount of deposition, but also the increase of specific cake resistance. A combined standard pore blocking and cake filtration model, using a critical pore size for the transition time determination, was developed and fit the experimental results well.