archives@tulane.edu / Ion specific effects are observed in a broad range of aqueous solutions. In particular, ion-specific effect in macromolecular systems are commonly known as the normal and reverse Hofmeister effects. This dissertation examines these Hofmeister effects in model examples and the protein ubiquitin, describing work to probe the thermodynamics of the non-covalent interactions behind these phenomena. Furthermore, how these ion specific effects can be utilized to control reactions in nano-spaces is also discussed. The direct interaction of anions with synthetic water-soluble molecules, including cyclodextrins and small-cavitands, has been proved to be useful models to study the thermodynamics of the interaction of anions with well-defined, non-polar pockets, and therefore to mimic the direct ionic interaction with more complicated macromolecules such as proteins. The effect of structure modification to the cyclodextrins and small-cavitands will be discussed. Ubiquitin is selected as the model protein to study the reverse Hofmeister effect and its mechanism. The effect on the changes in its biophysical properties, especially its aggregation and thermally induced unfolding, demonstrate that changes follow the reverse Hofmeister effect at low pH, and suggest that at higher pH normal, salting-in Hofmeister effects are manifest. The mechanism of these processes is explored with the HSQC NMR titrations to detect anion binding to specific points on the ubiquitin surface. Binding affinities were determined. The strong correlation of the binding affinity with the observation of the biophysical properties, including the aggregation and thermally induced unfolding, suggests that the reverse Hofmeister effect is directly driven by the anion specific interactions to preferred binding sites on the protein surface. The encapsulation and reactivity of an α,ω-amino halide guest within two supramolecular containers has been characterized. The NMR spectroscopy results suggest these long-chain guests adopt J-shaped conformation or motifs in the dimeric nano-capsule space. The kinetics of the macrocyclization reaction of this guest, was explored in the presence of different salts. Both anion and cation effects show the reaction rate is modulated by the ions in solution and follow the Hofmeister effect. / 1 / WEI YAO

The project described in this report were done as a Bachelor thesis in the course MSGC12, for a bachelor degree at the Innovation and design-engineering program at Karlstad University. The course is 22,5hp and goes for 20 weeks over the whole spring term. The project originated from an earlier project done with Swegon AB. The project goal is to find a design of a room thermostat, and demonstrate notably important features that can create an added value to Swegon or their costumers. This will later collaborate with another project that is going on simultaneously. These will unite and present a mutual product. The room thermostats existing today often has very plastic feel to them and is not very adaptable to the environments that they are placed in. They are also not very distinctive and they look pretty much the same regardless of maker. The method used in this project follows the steps set for the industrial product development process. A big part of this process is the iterative cycle were problem solving and life cycle perspective is important pillars. It is here that the modularity comes in. The project is based on a feasibility study with focus on finding innovative ways for the user to get data and make changes to their environment. To arrive at the final prototype, the project have gone through different analyses, discussions with the company, idea generation, patent check, workshop work, and concept screenings and partners in the project picked the concept which from their view were the best at Swegon. When these opinions were in, a 3d model were developed during the creation of said model, problems were encountered these were solved along the way. The model was then printed in a 3d printer. The prototype were then fitted with a light frame where the light could shine through and be projected onto the material. A complete prototype is made up of five parts, these are back plate, frame, plexiglass, light frame and material to project the symbols on. The product is not final but it points in a direction for the coming products.

No description available.

Les travaux concernent la mise au point et l'étude de microcapsules de composés naturels réticulés pour des applications en cosmétologie. / The study deals with the development of microcapsules from reticulated natural products, for cosmetological applications.

No description available.

Thesis advisor: Chia-Kuang Tsung / In order to enhance the selectivity of metal nanoparticle heterogeneous catalysts, a method for the encapsulation of metal nanoparticles by crystalline nanoporous materials was designed and implemented through a wet-chemical, capping-agent-mediated encapsulation strategy. Two thermally and chemically stable metal organic frameworks (MOFs) with different aperture sizes were chosen as the crystalline nanoporous layers for metal nanoparticle (NP) encapsulation. Successful encapsulation and good catalytic performance depended on understanding and engineering the interface between the metal catalyst core and the nanoporous shell. After the synthesis of the NPs-MOF composite, their catalytic activity and selectivity were studied. Two kinds of capping agents (polymer and surfactant) were used to demonstrate different mechanisms for NP encapsulation. The polymer (polyvinylpyrrolidone, PVP) induced interaction between the NP surface and MOF precursors while the surfactant (cetyltrimethylammonium bromide, CTAB) controlled the alignment between the metal nanoparticles and MOFs. Furthermore, the capping-agent-directed overgrowth could be a general method of not only loading various inorganic nanoparticles into MOF single crystals but also bridging two porous materials with totally different structures. MOF shells were further functionalized by postsynthetic linker exchange. By applying the process, a new concept was introduced for the formation of enlarged pore apertures by linker dissociation during MOF linker exchange, as demonstrated by the postsynthetic encapsulation of species much larger than the pore aperture of the MOF structure. Kinetic studies of linker exchange rely on the competition between associative and dissociative linker exchange mechanisms. It was found that guest encapsulation was enhanced under conditions that favored the dissociative pathway. Through kinetics studies, linker exchange rate was also found to vary in different solvents. The different exchange rates were then used to create hierarchical porosity in MOF structure, and a double-solvent-mediated overgrowth strategy was designed to form hollow and mesoporous MOF. The results help to provide new ideas for nanopores related heterogeneous catalysis. The discussion of active metal NP cores with a nanoporous shell, as a frontier core-shell material, may benefit further study in developing highly selective catalysts. / Thesis (PhD) — Boston College, 2016. / Submitted to: Boston College. Graduate School of Arts and Sciences. / Discipline: Chemistry.

Antimicrobial peptides are key actors in organisms€™ immune systems. They play an important role in phagocytosis, breaking bacteria membranes. They destroy the microbes, keeping them from repairing themselves, and therefore do not promote antimicrobial resistance. LL37 is a peptide produced by the human body. It is a short amino acid chain that is particularly active on the skin and mucous membranes. It has antimicrobial and fungal activity as well as wound healing properties, which makes it a very interesting active substance in wound treatment. However, its fragile and sensitive structure is a challenge to its use. Nowadays, encapsulation in a biocompatible polymer system is a promising technique in drug delivery, and presents a solution to LL37 administration and delivery. LL37 is a hydrophilic active substance, it will be trapped in PLGA (poly (lactic-co-glycolic acid)) by double emulsion and the microspheres will be shaped and stabilized by solvent evaporation. The capsules will be characterized by Dynamic Light Scattering (DLS) and Scanning Electron Microscopy. Their main features, drug loading, encapsulation efficiency and release profile, are determined using the Bradford assay. Since the peptide is expensive and delicate, it is important to optimize its encapsulation. For that reason, we will adapt the process to have the best drug loading as possible using water in oil in oil emulsions. For an external use, the capsules would be used over a few days, so having a fast release is very relevant. The larger the specific surface area, the faster the diffusion. For that reason, we will also study the impact of porosity on the release profile. As a result, different types of capsules will be synthesized, with higher porosity and by two processes: aqueous double emulsion and oil double emulsion. Their characteristic features and impact on bacterial pathogens will be determined and compared in order to determine their optimal synthesis process and formulation in given conditions of use.

Encapsulation is a wide spread industrial technique. The use of biopolymers to form capsules has an obvious advantage for food, biomedical or personal care applications, as they can be made of food grade and biodegradable materials. Polyelectrolyte complexes (PEC) have been widely used to form capsules by the multilayer technique, usually coating a solid core with a layer by layer deposition technique involving various steps of deposition of polyelectrolyte of opposite charge. In this thesis we focused on capsules made with a one step technique where a liquid drop containing a concentrated solution of the polycation is dropped into a dilute solution of the polyanionic solution. Chitosan was the natural polycation used, due to its interesting properties such as biodegradability, biocompatibility or muco-adhesion, and because it is one of the rare cationic polysaccharides which is safe to be used in food applications. The simple one step technique used to form these capsules brings an advantage in terms of manufacturing. The drop deformation due to the impact of droplets at the surface of a liquid bath was studied and the conditions for these droplets to detach from the surface and disperse into the solution were examined. It was found that a balance between the kinetic energy and the absorbed viscous energy of the drop during impact is necessary for the formation of capsules by this technique. Initial work was performed on capsules made with chitosan and polyanionic biopolymers such as alginate or pectins. However, these biopolymers are usually provided with a polydispersed molecular weight distribution and impurities. Polyacrylic acid was thus chosen to study the effect of molecular weight, charge density, and pH on the microstructure, mechanical, swelling and release behaviour of these capsules. The microstructure of the capsules was observed by cryo-scanning electron microscopy, and the effect of molecular weight charge density of the polyelectrolytes on the shell thickness were shown and related to the mechanical and release properties of the capsules. It was shown that the molecular weight has an important role as it determines the thickness of the shell. The charge density of the polyelectrolytes, which can be controlled by the pH and ionic strength of the solution, dictates the density of the shell. The study of the release properties of these capsules showed that they could be completely impermeable to molecules with a molecular weight higher than 2000 g/mol, and surprisingly, the capsules could withstand a wide range of pH extending beyond the pH where electrostatic interactions occur, as they only dissolved at extreme pHs of 2 and 12. Chitosan was also used to make swellable hydrogels microparticles, by cross-linking with glutaraldehyde. The swelling behaviour in gastro-intestinal environment was studied in vitro and in vivo using Magnetic Resonance Imaging techniques.

Le Cydia pommonella granulovirus (CPGV) est un insecticide naturel des ravageurs des pommes sensible à l’environnement extérieur (UV et dioxygène). Pour le protéger, nous avons encapsulé le CpGV dans des émulsions doubles de type eau dans huile dans eau (E/H/E). Cependant, l’utilisation des émulsions doubles requiert la maitrise de leur stabilité thermodynamique et la compréhension des mécanismes mis en jeu au cours de leur déstabilisation. C’est dans ce contexte que différents paramètres de formulation : procédé d’émulsification, type de stabilisant hydrophile, concentration en stabilisant lipophyle et en gouttelette d’eau, utilisation d’un agent anti-UV ont été testés pour étudier leur influence sur la libération du virus. Chaque formulation a fait l’objet de test d’efficacité sur les vergers et detransposition à l’échelle pilote afin de déterminer la formulation la plus efficace et pouvant être produit industriellement. / Cydia pommonella granulovirus (CpGV) is a natural insecticide pest of apples wich is sensitive to the external environment (UV and oxygen). To protect it, we have encapsulatedthe CpGV in double emulsions of water-in-oil-in-water (W / O / W). However, it’s necessary to understand the mechanisms involved in their destabilizationin order to master their thermodynamic stability. In that context, several various formulation parameters: emulsification processes, hydrophilic stabilizer type, lipophilic stabilizer concentration and water droplet, using a UV stabilizer were tested to study their influence on virus release. Each stable formulation undergoes efficiency tests in fields and pilot scale to determine the most effective formulation which could be industrially produced.

Les semiconducteurs organiques (SO) ont attiré une grande attention ces dernières années en raison de leur facilité de fabrication, de leurs modifications des propriétés optiques et électriques et de leur rentabilité. Ils forment la classe de matériaux les plus adaptés à l'électronique flexible et à la bioélectronique, en particulier en association avec des matériaux inorganiques / hybrides solubles en solution. Cependant, la mobilité des charges dans ces matériaux est fortement affectés par leur désordre structurel et énergétique introduit par les défauts qui "piègent" les transporteurs de charge. Selon l'emplacement physique des pièges et leur distribution en énergie, ils pourraient affecter de manière significative le transport de charge dans un dispositif. Le présent travail s'efforce de sonder l'interface et les états défectueux en masse dans des diodes à base de polymère. Au lieu de cela, une partie de l'étude implique de caractériser le système avec et sans encapsulation, en utilisant des techniques pour enregistrer le comportement de courant-tension à l'état stationnaire (IV), les transitoires d'extraction de charge par la tension augmentant linéairement (CELIV) et les courants transitoires d'injection en obscurité (DiTC), ainsi que la photoluminescence (PL) et l'électroluminescence (EL) des systèmes. Les mêmes caractéristiques ont été effectuées pour observer l'effet de pénétration de la lumière ultraviolet (UV) sur les systèmes. Tous les tests ont été effectués sur trois polymères différents, à savoir P3HT, MDMO:PPV et PCDTBT. La comparaison des dispositifs encapsulés et non encapsulés donne un aperçu des différences caractéristiques des mesurables lors de l'exposition à l'air et humidité. Les tests de pénétration lumineuse indiquent la modification de la fonction de travail de la cathode après une désorption d'oxygène assistée par UV sur l'interface polymère/cathode. Un effort simultané s'est traduit par une étude in situ de la dynamique de transport des charges dans les semi-conducteurs organiques sur une large gamme de temps à une échelle microscopique. / Organic semiconductors (OSs) have garnered a great attention in the recent years due to their ease of processibility, optical and electrical property-tunability, and to their cost-effectiveness. They form the class of materials most suitable for flexible electronics and bioelectronics, especially in association with solutionprocessable inorganic/hybrid materials. However, the charge mobility in these materials is strongly affected by their structural and energetic disorder introduced by the defects that ‘trap’ the charge carriers. Depending upon the physical location of the traps and their distribution in energy, they could significantly affect the charge transport in a device. The present work strives to probe the interface and bulk defect states in polymer-based diodes. In lieu of that, a part of the study involved characterizing the device with and without encapsulation, using techniques to record steady-state current-voltage (IV)behaviour, transients of charge extraction by linearly increasing voltage (CELIV) and dark-injection transient currents (DiTC), as well as photoluminescence (PL) and electroluminescence (EL) off the devices. The same characteristics have been carried out to observe the effect of ultra-violet (UV) lightsoak on the devices. All the tests were performed on three different polymers, namely P3HT, MDMO:PPV and PCDTBT. The comparison of the encapsulated versus unencapsulated devices gives an insight into characteristic differences in the measurables upon exposure to air and moisture. The light-soak tests indicate the modification of the cathode work function after a UV-assisted oxygen desorption off the polymer/cathode interface. A simultaneous effort went into an in-situ investigation of charge transport dynamics in organic semiconductors over wide time range at a microscopic scale.