Thesis (Ph.D.)--Georgia State University, 2008. / Title from file title page. Philo Hutcheson, committee chair ; Phill Gagne, Susan Talburt, Wayne Urban, committee members. Description based on contents viewed Sept. 28, 2009. Includes bibliographical references (p. 171-175).

Thesis (M.A.)--Ohio University, June, 2004. / Title from PDF t.p. Includes bibliographical references (p. 97-100)

Water is undoubtedly a key life element. Its importance is very clear from a religious perspective: “We made from water every living thing. Will they not then believe?” Surah Al-Anbiya verse 30 Also as highlighted in the United Nations resolution 64/292 which recognizes water as a basic necessity for human survival. As the world water demand grows, so does the need to use renewable water sources most available in the form of saline ocean water. Desalination of this water for potable use relies mainly on thermal and membrane-based technologies, mainly multi-stage flash (MSF), multi-effect distillation (MED), and seawater reverse osmosis (SWRO). However, these mature technologies are recognized for their high energy and chemicals use. To cope with these challenges, development of novel desalination processes is required to assure more sustainable water supply for the future. Membrane distillation (MD) has emerged as a process which combines advantages of both membrane and thermal technologies. It has a potential of being cost effective by utilizing renewable or waste heat energies as a driving force. Air gap membrane distillation (AGMD) is one of the four main MD configurations. AGMD’s main feature is the presence of an air gap which is enclosed between the membrane behind which flows the hot feed and condensation surface behind which flows a coolant. While improving the heat transfer across the membrane, the air gap negatively affects mass transfer resistance thereby reducing vapor flux and increasing process footprint. This dissertation investigates the effect of condensation plate surface modifications on AGMD process efficiency. The modifications are made by utilizing three different approaches including alterations of the surface shape and surface coating (to modify its contact angle) and by varying module inclination angle. A numerical simulation is carried out to determine the key factors which facilitate AGMD vapor flux increase. The second part of this thesis focuses on developing a promising novel approach utilizing Peltier’s process as a heat source to operate the MD process with less energy requirement. The morphological modifications of a plate surface positively affected vapor flux because of the air gap reduction. The highest vapor fluxes were observed when condensation plate had hydrophilic coatings. Based on the observed results, a thin film-wise condensation was suggested as a primary condensation mechanism. The formed film reduced the air gap thickness and this effect was more prominent at 45° when condensation plate was positioned over the membrane surface. A 2-dimensional mathematical model was developed and the model results agreed with the experimental data. Finally, the thermocouple-based MD concept was introduced and experimentally validated.

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Indiana University-Purdue University Indianapolis (IUPUI) / The cell membrane serves as a barrier between the interior and exterior of a living cell. Its main structural component is the lipid bilayer, which is composed of various kinds of lipids that segregate into domains. These lipid domains, distinguished in composition and physical properties from the bulk lipids that surround them, are believed to modulate the function of resident proteins by providing an appropriate lipid environment. Polyunsaturated fatty acids (PUFA) are a type of fatty acid that contain multiple C=C double bonds. They have a lot of health benefits, which may originate in part due to their incorporation into lipids in the plasma membrane. Hypotheses that PUFA-containing lipids laterally separate into domains and/or modulate the structure of existing domains have been raised to explain the fundamental role played by PUFA. In our research, we use molecular dynamics (MD) simulations to simulate model membranes composed of PUFA-containing phospholipids and to investigate their interaction with cholesterol and vitamin E that are influential membrane constituents. The presumptive function for vitamin E in membranes is to protect PUFA against oxidation. Although the chemistry of the process is well established, the role played by the molecular structure that we address with atomistic molecular dynamics (MD) simulations remains controversial. We compared the behavior of vitamin E in lipid bilayers composed of 1-stearoyl-2-docosahexaenoylphosphatidylcholine (SDPC, 18:0-22-6PC) and 1-stearoyl-2-oleoylphosphatidylcholine (SOPC, 18:0-18:1PC) via all-atom MD simulations at 37° C. SDPC represents a PUFA-containing lipid, and SOPC serves as monounsaturated control. From the calculation of van der Waals energy of interaction between vitamin E and fatty acid (FA) chains, we found higher probability that the PUFA chains surround the chromanol head group on vitamin E. This is further demonstrated by probability density maps of acyl chains around vitamin E molecules. Also, an ability to more easily penetrate deep into the PUFA containing bilayer of vitamin E is detected by faster flip-flop rate of vitamin E observed in the SDPC bilayers. These results showed that the high disorder of polyunsaturated docosahexaenoic acid (DHA) chains allows vitamin E to easily tunnel down into the bilayer and often brings the PUFA chains up to the surface of the bilayer, improving the likelihood that the reactive (hydroxyl) group on vitamin E would encounter a lipid peroxyl radical and terminate the oxidation process. Thus, the simulations indicate that the molecular structure of vitamin E supports its role as an antioxidant in a PUFA-containing membrane. A subsequent study on the partitioning of vitamin E into PUFA-containing lipids was done by analyzing the binding energy of vitamin E in the corresponding lipid bilayer. The binding energy is obtained from the potential of mean force (PMF) profile of vitamin E alone the membrane normal direction (z), which is calculated from umbrella sampling MD simulations. We found the binding in SDPC is smaller in SOPC, indicating that vitamin E does not prefer PUFA-containing phospholipids. The flip-flop rate was also estimated from the PMF profile, confirming that vitamin E flip-flops across the SDPC bilayer more easily than the SOPC bilayer. From the simulations it was noted that the membrane deforms as vitamin E is pulled out, which suggests interactions between the phospholipids contribute to the binding energy of the vitamin E. In a final study, a comparison was made between the effect on membrane organization of the three types of long chain omega-3 (n-3) PUFA found in fish oils: eicosapentaenoic acid (EPA, 20:5), DHA (22:6) and docosapentaenoic acid (DPA, 22:5). MD simulations were run on lipid bilayers composed of 1-stearoyl-2-eicosapentaenoylphosphatidylcholine (EPA-PC, 18:0-20:5PC), 1-stearoyl-2-docosapentaenoylphosphatidylcholine (DPA-PC, 18:0-22:5PC), SDPC (DHA-PC, 18:0-22:6PC) and, as a monounsaturated control, SOPC (OA-PC, 18:0-18:1PC) in the absence and presence of cholesterol. By analyzing the physical properties such as membrane order and thickness, we found all three n-3 PUFAs disorder the membrane. The disordering is greatest with EPA and least with DPA. Unique among the n-3 PUFA-containing membranes, there is region of high order in the upper portion of the DPA chain. The PUFA-containing lipids were found to less favorably interact with cholesterol compared to the OA-containing lipid, which is caused by their disorder. We speculate that differences between DPA, DHA and EPA might potentially modulate their effect on lipid domain formation.

Thesis (Ph. D.)--University of Maryland, College Park, 2006. / Includes bibliographical references (p. 188-199) and abstract.

This thesis reports on algorithmic design and software development completed for the Medipix All Resolution System (MARS) multi-energy CT scanner. Two areas of research are presented - the speed and usability improvements made to the post-reconstruction material decomposition software; and the development of two algorithms designed for the implementation of a novel voxel system into the MARS image reconstruction chain. The MARS MD software package is the primary material analysis tool used by members of the MARS group. The photon-processing ability of the MARS scanner is what makes material decomposition possible. MARS MD loads reconstructed images created after a scan and creates a new set of images, one for every individual material within the object. The software is capable of discriminating at least six different materials, plus air, within the object. A significant speed improvement to this program was attained by moving the code base from GNU Octave to MATLAB and applying well known optimisation routines, while the creation of a graphical user interface made the software more accessible and easy to use. The changes made to MARS MD represented a significant contribution to the productivity of the entire MARS group. A drawback of the MARS image reconstruction chain is the time required to generate images of a scanned object. Compared to commercially available CT systems, the MARS system takes several orders of magnitude longer to do essentially the same job. With up to eight energy bins worth of data to consider during reconstruction, compared to a single energy bin in most com- mercial scanners, it is not surprising that there is a shortfall. A major performance limitation of the reconstruction process lies in the calculation of the small distances travelled by every detected photon within individual portions of the reconstruction volume. This thesis investigates a novel volume geometry that was developed by Prof. Phil Butler and Dr. Peter Renaud, and is designed to partially mitigate this time constraint. By treating the volume as a cylinder instead of a traditional cubic structure, the number of individual path length calculations can be drastically reduced. Two sets of algorithms are prototyped, coded in MATLAB, C++ and CUDA, and finally compared in terms of speed and visual accuracy.

Philosophiae Doctor - PhD / Neisseria meningitidis (the meningococcus), the causative agent of meningococcal disease (MD) was identified in 1887 and despite effective antibiotics and partially effective vaccines, Neisseria meningitidis (N. meningitidis) is the leading cause worldwide of meningitis and rapidly fatal sepsis usually in otherwise healthy individuals. Over 500 000 meningococcal cases occur every year. These numbers have made bacterial meningitis a top ten infectious cause of death worldwide. MD primarily affects children under 5 years of age, although in epidemic outbreaks there is a shift in disease to older children, adolescents and adults. MD is also associated with marked morbidity including limb loss, hearing loss, cognitive dysfunction, visual impairment, educational difficulties, developmental delays, motor nerve deficits, seizure disorders and behavioural problems. Antimicrobial peptides (AMPs) are molecules that provide protection against environmental pathogens, acting against a large number of microorganisms, including bacteria, fungi, yeast and virus. AMPs production is a major component of innate immunity against infection. The chemical properties of AMPs allow them to insert into the anionic cell wall and phospholipid membranes of microorganisms or bind to the bacteria making it easily detectable for diagnostic purposes. AMPs can be exploited for the generation of novel antibiotics, as biomarkers in the diagnosis of inflammatory conditions, for the manipulation of the inflammatory process, wound healing, autoimmunity and in the combat of tumour cells. Due to the severity of meningitis, early detection and identification of the strain of N. meningitidis is vital. Rapid and accurate diagnosis is essential for optimal management of patients and a major problem for MD is its diagnostic difficulties and experts conclude that with an early intervention the patient’ prognosis will be much improved. It is becoming increasingly difficult to confirm the diagnosis of meningococcal infection by conventional methods. Although polymerase chain reaction (PCR) has the potential advantage of providing more rapid confirmation of the presence of the bacterium than culturing, it is still time consuming as well as costly. Introduction of AMPs to bind to N. meningitidis receptors could provide a less costly and time consuming solution to the current diagnostic problems. World Health Organization (WHO) meningococcal meningitis program activities encourage laboratory strengthening to ensure prompt and accurate diagnosis to rapidly confirm the presence of MD. This study aimed to identify a list of putative AMPs showing antibacterial activity to N. meningitidis to be used as ligands against receptors uniquely expressed by the bacterium and for the identified AMPs to be used in a Lateral Flow Device (LFD) for the rapid and accurate diagnosis of MD.

Thesis (M.A.)--West Virginia University, 2002. / Title from document title page. Document formatted into pages; contains iv, 132 p. : ill., maps. Vita. Includes abstract. Includes bibliographical references (p. 120-127).