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Changes in the mechanics of the lens capsule of the eye arising from alterations of its native configuration can lead to undesirable clinical results. One example is the surgical introduction of a hole into the lens capsule and subsequent removal of the cloudy lens during cataract surgery. The adverse effect is secondary cataract on the posterior lens capsule, brought about by a sudden proliferation of lens epithelial cells in the region. Understanding the biomechanics of the anterior lens capsule is necessary in order to model its behavior under various physiological conditions and predict its response to alterations and perturbations such as those during cataract surgery. Such knowledge will help in the improvement of techniques during cataract surgery, and in the design of artificial intraocular lens. In this study we present, for the first time, results that demonstrate that the anterior lens capsule exhibits non-homogeneity and regionally varying anisotropy. We also compute stresses in the lens capsule due to normal loading conditions and procedures such as a capsulorhexis.

The structure of a polymeric material has a great influence in many fundamental scientific areas as well as in more applied science, since it affects the diffusion, permeability, mechanical strength, elasticity, and colloidal properties of the materials. The results in this thesis demonstrate that it is possible to fabricate solid and hollow cellulose spheres with a cellulose shell and encapsulated gas, liquid or solid particles and with a sphere size ranging from a few hundreds of nanometres to several millimetres, all with a tailored design and purpose. The sizes of the different spheres have been controlled by three different preparation methods: large cellulose macrospheres by a solution solidification procedure, hollow micrometre-sized cellulose spheres by a liquid flow-focusing technique in microchannels, and nanometre-sized cellulose spheres by a membrane emulsification technique.  The spheres were then modified in different ways in order to functionalize them into more advanced materials. This thesis demonstrates how to control the cellulose sphere dimensions and the wall-to-void volume ratio, the elasticity and the functionality of the spheres as such, where they were prepared to be pH-responsive, surface specific and X-ray active. These modifications are interesting in several different types of final materials such as packaging materials, drug release devices or advanced in vivo diagnostic applications. In the more fundamental science approach, surface-smooth solid cellulose spheres were prepared for characterization of the macroscopic work of adhesion when a cellulose surface is separated from another material. Using these ultra-smooth macroscopic cellulose probes, it is possible to measure the compatibility and the surface interactions between cellulose and other materials which provide an important tool for incorporating cellulose into different composite materials. / <p>QC 20140829</p>

Thesis--University of Stellenbosch. / Bibliography: p. 136-146.

Master of Science / Biochemistry and Molecular Biophysics Interdepartmental Program / John M. Tomich / Nanocapsules have become more popular as potential therapeutic agents in recent years. Though liposomes are the most popular and well-studied, nanocapsules made of peptides have their distinct advantages as the research behind them intensifies. Branched Amphiphilic Peptide Capsules (BAPCs) are a type of self-assembling nanocapsules that are made up of two similar branched, amphiphilic, chemically synthesized peptides. These peptides self-assemble into bilayer delimited capsules capable of encapsulating solutes and even small proteins in aqueous solution. Previous studies have shown that these nanocapsules are taken up by cells in culture without negative effects and can be given to an organism, distributed throughout the organism without cytotoxic effects, suggesting a possible future as a therapeutic nanoparticle. For use as a therapeutic system, the understanding of how these BAPCs behave in the presence of sodium and chloride, two very common biological ions, must be understood and characterized. Previously published work showed that the BAPC bilayer is semipermeable and excludes sodium and chloride ions. Current research has expanded on this. Besides being semipermeable, this bilayer is also a dynamic membrane that has the ability to expand and contract due to osmotic pressure from ions in solution. Eosin Y, an autoquenching dye, has been used for many of the studies to monitor the behavior and the amount of water within the BAPCs. Having insight into how the BAPCs change under physiological conditions is necessary if these nanoparticles are to be used in a clinical setting and may open doors to new uses.

<p>Kingella kingae is a bacterial pathogen that is increasingly recognized as an etiology of septic arthritis, osteomyelitis, bacteremia, and endocarditis in young children. The pathogenesis of K. kingae disease starts with bacterial adherence to the respiratory epithelium of the posterior pharynx. Previous work has identified type IV pili and a trimeric autotransporter protein called Knh (Kingella NhhA homolog) as critical factors for adherence to human epithelial cells. Additional studies established that the presence of a polysaccharide capsule interferes with Knh-mediated adherence. Given the inhibitory role of capsule during adherence we sought to uncover the genes involved in capsule expression to understand how capsule is elaborated on the cell surface. Additionally, this work aimed to further characterize capsule diversity among K. kingae clinical isolates and to investigate the relationship between capsule type and site of isolation. </p><p>We first set out to identify the carbohydrates present in the K. kingae capsule present in the prototype strain 269-492. Glycosyl composition and NMR analysis of surface extractable polysaccharides demonstrated two distinct polysaccharides, one consisting of GalNAc and Kdo with the structure →3)-β-GalpNAc-(1→5)-β-Kdop-(2→ and the other containing galactose alone with the structure →5)-β-Galf-(1→. </p><p>To discern the two polysaccharides we disrupted the ctrA gene required for surface localization of the K. kingae polysaccharide capsule and observed a loss of GalNAc and Kdo but no effect on the presence of Gal in bacterial surface extracts. In contrast, deletion of the pamABCDE locus involved in production of a reported galactan exopolysaccharide eliminated Gal but had no effect on the presence of GalNAc and Kdo in surface extracts. These results established that K. kingae strain KK01 produces a polysaccharide capsule with the structure →3)-β-GalpNAc-(1→5)-β-Kdop-(2→ and a separate exopolysaccharide with the structure →5)-β-Galf-(1→. </p><p>Having established that K. kingae produces a capsule comprised of GalNAc and Kdo, we next set out to identify the genetic determinants of capsule through a transposon mutagenesis screen. In addition to the previously identified ctrABCD operon, lipA, lipB, and a putative glycosyltransferase termed csaA (capsule synthesis region A gene A) were found to be essential for the production of surface-localized capsule. The ctr operon, lipA, lipB, and csaA were found to be present at unlinked locations throughout the genome, which is atypical for gram-negative organisms that elaborate a capsule dependent on an ABC-type transporter for surface localization. Through examining capsule localization in the ctrA, lipA, lipB, and csaA mutant strains, we determined that the ctrABCD, lipA/lipB, and csaA gene products respectively function in capsule export, assembly, and synthesis, respectively. The GalNAc transferase and Kdo transferase domains found in CsaA further support its role in catalyzing the synthesis of the GalNAc-Kdo capsule in the K. kingae prototype strain.</p><p>To investigate the capsule diversity that exists in K. kingae we screened a panel of strains isolated from patients with invasive disease or healthy carriers for the csaA capsule synthesis locus. We discovered that Kingella kingae expresses one of 4 capsule synthesis loci (csa, csb, csc, or csd) associated with a capsule consisting of Kdo and GalNAc (type a), Kdo and GlcNAc (type b), Kdo and ribose (type c), and GlcNAc and galactose (type d), respectively. Cloning of the csa, csb, csc, or csd locus into the empty flanking gene region in a non-encapsulated mutant (creation of an isogenic capsule swap) was sufficient to produce either the type a, type b, or type c capsule, respectively, further supporting the role of these loci in expression of a specific polysaccharide linkage. Capsule type a and capsule type b accounted for 96% of invasive strains. Conversely, capsule type c and capsule type d were found disproportionately among carrier isolates, suggesting that capsule type is important in promoting invasion and dissemination. </p><p>In conclusion, we discovered that Kingella kingae expresses a polysaccharide capsule and an exopolysaccharide on its surface that require distinct genetic loci for surface localization. Further investigation into genetic determinants of encapsulation revealed the loci ctrABCD, lipA/lipB, and a putative glycosyltransferase are required for capsule expression, with the gene products having roles in capsule export, assembly, and synthesis, respectively. The putative glycosyltransferase CsaA was determined to be a bifunctional enzyme with both GalNAc-transferase and Kdo-transferase activity. Furthermore, we discovered a total of 4 capsule types expressed in clinical isolates of K. kingae, each with a distinct capsule synthesis locus. The variation in the proportion of capsule types found between invasive strains and carriage strains suggest that capsule type is important in promoting invasion and dissemination. Taken together, this work expands our knowledge of the capsule types expressed among K. kingae carrier and invasive isolates and provides insights into the common genetic determinants of capsule expression. These contributions may lead to selecting clinically relevant capsule types to develop into a capsule based vaccine to prevent K. kingae colonization.</p> / Dissertation

Twist Capsules are rotating electrical connections that are used when low noise electrical signals are required between a stationary connector and a mechanically oscillating one. Twist capsules are used throughout industry especially in areas that require exceptionally clean signals such as the space satellite industry and military applications. Due to the high cost of replacing parts on satellites launched into space and life-sustaining aspects of military applications, accurate modeling of these devices is essential to predict their behavior. Clock spring twist capsules use a flex tape, copper traces between two layers of Kapton, which rolls onto itself tightening against the shaft at one extreme and rolling out against the frame at the other extreme. This cyclic tightening and loosing can cause stresses on these flex tapes consequently, resulting in their failure due to fatigue. Therefore, it is imperative that some method be used to estimate the stresses in the flex tape in order that the optimal design parameters may be calculated. The natural progression from estimating the stresses is to predict the life of the twist capsule. Current techniques involve iteratively building physical models and heritage (what has worked in the past will work in the future) to build twist capsules. This methodology has been sufficient, but a large factor of safety is used during design to cover the lack of assurance in the method. This thesis proposes a new design method using clock spring equations to estimate the torque in twist capsules and the stresses induced into the flex tapes. This new design method accurately predicts operating range, torque, and stress in the normal operating range of the twist capsule sufficient enough for design purposes in a fraction of the amount of time it would normally take to design a twist capsule. / Master of Science

Klebsiella spp. are coliform bacteria that cause mastitis in dairy cattle and account for high mortality rates in infected cows leading to a significant financial loss. Recent outbreaks indicate that within farms a single strain can be responsible for clinical signs in multiple animals. Identification of the virulence of factors enabling Klebsiella spp. survival in the mammary glands of multiple animals may provide insight into host adaptation. In this study, Klebsiella spp. strains were evaluated for their ability to evade neutrophil killing, the primary immune defense in the bovine mammary gland. Our research focused on capsule and biofilm production by Klebsiella spp. when strains were grown in Luria Broth or skim milk to examine the effects on evasion of neutrophil killing. Biofilm production was not significantly related to the ability to resist neutrophil killing nor was capsule (P = 0.29). Farm (P < 0.001), media type (P < 0.005), and strain type by cow (P < 0.001) were found to play significant roles in neutrophil evasion. This suggests farm of origin, media type used, and cow all may play a role in evasion of neutrophils by Klebsiella spp. Further evaluation of virulence factor expression in different media types and the role of individual cow immune responses may provide insight into ability of Klebsiella spp. to cause outbreaks of mastitis in multiple animals. / Master of Science

archives@tulane.edu / Enzymes are most powerful catalysts in Nature. Despite decades of research, there are still many open questions surrounding the mechanisms by which enzymes catalyze reactions. Supramolecular chemists have made lots of effort to designing a variety of host molecules to mimic enzymes over the last decade. They aim to understand the power of noncovalent forces and how local environment can be involved in enzymes’ catalytic functions. In our studies, two synthetic water-soluble deep cavity cavitands with different electrostatic potential (EP) that can provide well-defined nano-spaces and can be encapsulated with guests through hydrophobic effect were utilized to investigative the inner guests’ pKa shifts and reactions. First, pKa shifts of thiol guests in deep cavity cavitands have been examined. Here we utilize supramolecular capsules assembled via the hydrophobic effect to encapsulate guests and control their acidity. We found that the greatest impact on the acidity of the bound guests is the position of the acid group in the yotoliter space. Moreover, the nature of the electrostatic potential field (EPF) generated by charged solubilizing groups also plays an important role in acidity, as does the counter ion complexing to the outer surface of the capsule. In summary, these results suggest an electrostatic potential field (EPF) engendered by remote solubilizing groups can affect reactions inside of confined spaces. Second, macrocyclization reactions were investigated in two different electrostatic potential (EP) nano capsules. Here, we quantify these effects through acidity and cyclization rate by the size of the encapsulated guests, which confirmed primary role of Coulombic forces with a simple mathematical model approximating the capsules as Born spheres within a continuum dielectric. These results reveal the reaction rate accelerations possible under Coulombic control and highlight important design criteria for nanoreactors. / 1 / Xiaoyang Cai

In the second part, after performing in-vitro experiments to measure the resistant force of the small intestine, we propose a magnetic actuation method. The magnetic marker for localization acts as a seed to be actuated by multiple coils placed outside of the human body. The basic idea is that the magnetic seed is subject to a force and a torque in a magnetic field. An efficient computation scheme is designed and implemented to calculate the coil currents for real-time actuation. Simulations are performed on a six-coil actuation system to evaluate the method. As an alternative method, an internal actuator, which consists of a magnetic spring and can propel itself forward under an alternating current, is introduced to increase the mobility of the capsule and decrease the demand for a strong external field. The external magnetic field is also simulated to orient the internal actuator. / The development of wireless capsule endoscope realizes the examination of the whole gastrointestinal tract. The technology reduces patients' pain and benefits the doctors as well. However, it loses some functions that conventional endoscope owns because of the passive locomotion mode. To improve the situation, an active capsule endoscope is preferred by the community. / We put emphasis on two important problems in design of an active capsule endoscope: localization and actuation. The first part of our work focuses on the study of localization of the capsule taking advantage of the magnetic field. A small permanent magnet is enclosed in the capsule as a marker, and a tracking method is proposed based on the modelling of the marker as an ideal dipole. The five localization parameters are computed by minimizing the differences between the theoretical field values and sensing signals using Levenberg-Marquardt algorithm. One-axis Hall sensors and three-axis magnetoresistive sensors are employed respectively to implement the localization method. The system performance is evaluated by a series of tracking experiments. / Wang Xiaona. / "September 2006." / Adviser: Max Meng. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1771. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 155-171). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.