Dissertations / Theses on the topic 'Self assembly'
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Fox, Michael Jacob. "Stochastic self-assembly." Thesis, Georgia Institute of Technology, 2010. http://hdl.handle.net/1853/34741.
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We present methods for distributed self-assembly that utilize simple rule-of-thumb control and communication schemes providing probabilistic performance guarantees. These methods represents a staunch departure from existing approaches that require more sophisticated control and communication, but provide deterministic guarantees. In particular, we show that even under severe communication restrictions, any assembly described by an acyclic weighted graph can be assembled with a rule set that is linear in the number of nodes contained in the desired assembly graph. We introduce the concept of stochastic
stability to the self-assembly problem and show that stochastic stability of desirable configurations can be exploited to provide probabilistic performance guarantees for the process. Relaxation of the communication restrictions allows simple approaches giving deterministic guarantees. We establish a clear relationship between availability of communication and convergence properties. We consider Self-assembly tasks for the cases of many and few
agents as well as large and small assembly goals. We analyze sensitivity of the presented process to communication errors as well as ill-intentioned agents. We discuss convergence rates of the presented process and directions for improving them.
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Spanton, Robert. "Stateful self-assembly." Thesis, University of Southampton, 2013. https://eprints.soton.ac.uk/355888/.
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Nature shows us many organised structures that form through interactions between their components with little external guidance. These self-assembling systems range from simple crystals to considerably more complex biological structures and organisms. Inspired by these systems, the development of programmable self assembling systems could lead to mass manufacturing processes that produce individually unique items. Current artificial self-assembling systems involve small numbers of centimetre-scale components, and have not resulted in structures anywhere near the complexity seen in natural systems. This thesis argues that to advance artificial self-assembling systems towards this complexity, the statistics of the interactions within self-assembling systems need to be empirically examined and understood. However, the pursuit of this involves the resolution of a variety of technical challenges. These are approached in this work through the development of a self-assembly toolkit that allows the collection of these statistics from a physical system with larger numbers of components than in previous works. A novel capacitive communication interface is developed for the components of this toolkit, which allows messaging between neighbouring components that are constrained to the surface of a plane. As self-assembling components reduce in size towards the microscale, the penalty for incorrect activation of a component’s binding mechanism is likely to increase. With this in mind, this capacitive communication interface is optimised to provide spatial alignment sensing, with the aim of allowing informed binding mechanism activation. The toolkit developed in this work uses components that are constrained to two degrees of freedom of motion. In pursuit of the development of programmable self-assembling components for 3D structures, a new design of alignment sensor for use in 3D is created. Simulation of this sensor, which is developed using an evolutionary algorithm, indicates that it is suited for detecting the alignment of components with three degrees of freedom. Approaches using computer vision are developed for the spatial tracking of the components of the toolkit, allowing the collection of empirical data regarding the interaction of components. The technical advances described within this work will allow the progression of data-driven self-assembly process design.
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Chen, Ho-Lin. "Robust self-assembly /." May be available electronically:, 2007. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Dillenback, Lisa M. Keating Christine Dolan. "Self-assembly and controlled assembly of nanoparticles." [University Park, Pa.] : Pennsylvania State University, 2008. http://etda.libraries.psu.edu/theses/approved/WorldWideIndex/ETD-2613/index.html.
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Williams, Richard James. "Enzyme assisted self-assembly." Thesis, University of Manchester, 2008. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.496231.
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Self-assembling peptide systems provide a pathway for the formation of complex molecular assemblies from relatively simple designed molecules. Stimuli which have been used to trigger the self-assembly (SA) process in aqueous conditions include temperature, pH, ionic strength, and solvent exchange. Additionally, enzymes may be used to selectively control the self-assembly process; enzymes are uniquely chemo-, regio-, and enantioselective, and work naturally under mild conditions without disrupting biological Interactions.
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Mayans, Tayadella Enric. "Self-assembly of phenylalanine derivatives." Doctoral thesis, Universitat Politècnica de Catalunya, 2017. http://hdl.handle.net/10803/461917.
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Since the pioneering work of Reches and Gazit in 2003, in which the formation of diphenylalanine (FF) nanotubes in aqueous solution was discovered, significant efforts have been made to develop a new generation of biomaterials based on the self-assembly of aromatic peptides. From recent investigations, the self-assembly of phenylalanine homopeptides can be understood by a combination of hydrogen bonding and repeated aromatic stacking interactions.
In this Thesis, new phenylalanine homo-oligopeptide derivatives have been synthetized in order to test their self-assembly capability and to examine the influence of the chemical structure and the external conditions. Although, the terminal head-to-tail NH3 +···–OOC interactions in the unprotected homopeptides are shown to stabilize the peptide assemblies, chemical modulation has been introduced through the incorporation of the N- and C- protections, such as aromatic blocking groups (Chapter 4 and 5.2), azide-alkyne coupling groups (Chapter 3.2) or trifluoroacetate anion (Chapter 3.1). In Chapter 4, three FFFF-based peptides have been synthetized to study the role of the head-to-tail NH3 +···–OOC interactions in the assembly of
FFFF-derivatives. Although these interactions are not possible upon the incorporation of the NFmoc and C-OBzl protections, defined hierarchical assemblies arising from p-p stacking interactions have been found.
In Chapter 6, new hybrid polypeptide/polylactide conjugates have been prepared through ring opening polymerizations to reveal the effect of the constitutive polylactide block. Whereas the crystallization from the melt gave rise to spherulites from lamellar arrangements, previously reported phenylalanine-oligopeptide hierarchical morphologies have been observed from diluted solutions.
We report that the homopeptide length also plays a significant role in the supramolecular organization of phenylalanine derivatives. First, in Chapter 5.2, theoretical calculations have indicated that the stability of Phe-homopeptides capped with two fluorenyl functionalities increases with the length of the Phe-segment, adopting an antiparallel b-sheet arrangement. While the existence of diverse polymorphs suggests that p-p stacking interactions involving fluorenyl groups result in different stable conformations, they are more versatile, in terms of molecular selfassociation, than hydrogen bonds. Besides, the capacity of FFF to assemble in very diverse supramolecular structures has been found to be greater than that exhibited by its homologues with an even number of Phe residues (Chapter 5.1). Additionally, spherulites from the prepared diblock copolymers with a distinctive lamellar disposition (i.e. flat-on or edge-on) and/or dendritic structures have been identified in function of the length of the PPhe block (Chapter 6).
Results have evidenced not only the remarkable control exerted by the characteristics of the environment (i.e. the solvents mixture, temperature, the ionic strength, and the peptide concentration) in the organization of the assemblies, but also by the substrate (Chapter 5.3).
Depending on the conditions, molecules can organize into bundled arrays of nanotubes, stacked braids, corkscrew-like, doughnut/volcano-like, spherulitic microstructures and/or triaxial ellipsoid-like nodules. Peptide···peptide interactions, peptide···surface interactions and the surface roughness have been detected as key factors for the shape, dimensions and stability of the hierarchical assemblies. The proposed mechanisms for the formation of supramolecular structures have reflected how the structural nucleation and hierarchical growing are controlled through the
balance between peptide···peptide and peptide···solvent interactions, which in turn are regulated by the peptide concentration and the polarity of the solvent mixture used to dissolve the peptide, respectively.
Tuning the structure of Phe-derivatives by changing the medium used in the mixture, as well as the surface, is a very attractive feature to expand the potential utility of peptide assemblies in different fields, for example as molecular carriers and delivery systems. The wide range of available surfaces offers a valuable tool for the development of bionanotechnological applications based on hierarchical peptide assemblies. Indeed, the ability of plasma treated polystyrene for stabilizing well-defined dendritic structures has been found to be particularly noticeableEn aquesta tesis, nous homooligopèptids derivats de fenilalanina ha estat sintetitzats per tal d'estudiar la seva capacitat d'autoorganització i examinar la influencia de l'estructura química i les condicions externes. Encara que les interaccions NH3+···-OOC cap-a-cua en els homopèptids desprotegits mostren estabilitzar les estructures peptídiques, s'han introduït funcionalitzacions químiques a través de la incorporació de proteccions a N- i C-, com per exemple, grups bloquejadors aromàtics, grups d'acoblament azida-alquí, l'anió trifluoroacetat o un bloc de polilàctide. Diferents capítols estan dedicats a mostrar que la llargada del bloc d'homopèptid també juga un paper rellevant en l'organització supramolecular dels derivats de fenilalanina. Els resultats publicats evidencien no només el control que exerceixen les característiques de l'ambient sinó també del substrat. Les interaccions pèptid··· pèptid, pèptid···superfície i la rugositat superficial han estat assenyalades com a factors clau que defineixen la forma, les dimensions i l'estabilitat de les estructures jerarquitzades.
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Vikramaditya, Barmeshwar. "Micromanipulation using self assembly strategies /." Diss., ON-CAMPUS Access For University of Minnesota, Twin Cities Click on "Connect to Digital Dissertations", 2001. http://www.lib.umn.edu/articles/proquest.phtml.
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Gutzler, Rico. "Surface-Confined Molecular Self-Assembly." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-127201.
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Nellis, Michael. "Self assembly of complex structures." [Tampa, Fla.] : University of South Florida, 2007. http://purl.fcla.edu/usf/dc/et/SFE0002280.
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Yin, Jinsong. "Self-assembly of ordered nanostructures." Diss., Georgia Institute of Technology, 2000. http://hdl.handle.net/1853/19116.
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Li, Lin. "Automated self-assembly programming paradigm." Thesis, University of Nottingham, 2008. http://eprints.nottingham.ac.uk/10468/.
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Self-assembly is a ubiquitous process in nature in which a disordered set of components autonomously assemble into a complex and more ordered structure. Components interact with each other without the presence of central control or external intervention. Self-assembly is a rapidly growing research topic and has been studied in various domains including nano-science and technology, robotics, micro-electro-mechanical systems, etc. Software self-assembly, on the other hand, has been lacking in research efforts. In this research, I introduced Automated Self-Assembly Programming Paradigm (ASAP²), a software self-assembly system whereby a set of human made components are collected in a software repository and later integrated through self-assembly into a specific software architecture. The goal of this research is to push the understanding of software self-assembly and investigate if it can complement current automatic programming approaches such as Genetic Programming. The research begins by studying the behaviour of unguided software self-assembly, a process loosely inspired by ideal gases. The effect of the externally defined environmental parameters are then examined against the diversity of the assembled programs and the time needed for the system to reach its equilibrium. These analysis on software self-assembly then leads to a further investigation by using a particle swarm optimization based embodiment for ASAP². In addition, a family of network structures is studied to examine how various network properties affect the course and result of software self-assembly. The thesis ends by examining software self-assembly far from equilibrium, embedded in assorted network structures. The main contributions of this thesis are: (1) a literature review on various approaches to the design of self-assembly systems, as well as some popular automatic programming approaches such as Genetic Programming; (2) a software self-assembly model in which software components move and interact with each other and eventually autonomously assemble into programs. This self-assembly process is an entirely new approach to automatic programming; (3) a detailed investigation on how the process and results of software self-assembly can be affected. This is tackled by deploying a variety of embodiments as well as a range of externally defined environmental variables. To the best of my knowledge, this is the first study on software self-assembly.
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Chremos, Alexandros. "Self assembly in soft matter." Thesis, University of Edinburgh, 2009. http://hdl.handle.net/1842/4010.
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The term “soft matter” applies to a variety of physical systems, such as liquids, colloids, polymers, foams, gels, and granular materials. The most fascinating aspect of soft matter lies in the fact that they are not atomic or molecular in nature. They are instead macromolecular aggregates, whose spatial extent lies in the domain 1 nm to 1 ¹m. Some of the most important examples of soft matter are polymers, which exhibit intriguing and useful physical properties. In this work, the adsorption and self assembly of linear and star polymers on smooth surfaces are studied using coarse-grained, bead-springmolecular models and Langevin dynamics computer simulations. The aim is to gain insight on atomic-forcemicroscopy images of polymer films on mica surfaces, adsorbed from dilute solution following a good solvent-to-bad solvent quenching procedure. In the case of linear polymers, under certain experimental conditions, a bimodal cluster distribution is observed. It is demonstrated that this type of distribution can be reproduced in the simulations, and rationalized on the basis of the polymer structures prior to the quench. In addition to providing insight on experimental observations, the simulation results support a number of predicted scaling laws such as the decay of the monomer density as a function of distance from the surface, and the scaling of the filmheight with the strength of the polymer-surface interactions. Star polymers represent a special class of polymers, in which one end of each linear chain is tethered to a small central core to forma single particle. The discovery of these molecules led to the synthesis of a wide range of new materials. Their structures are effectively considered as intermediate between those of colloids and linear polymers. We explore the behaviour of the star polymers (which are like “soft colloids”) in the proximity of a surface, using Langevin dynamics simulations. A number of different measurements such as the height, radius of gyration, and asphericity of adsorbed stars with different number of arms, are shown to provide valuable insights on experimental findings. The simplest soft matter systems consist of spherical, rigid colloidal particles. Examples of such particles are chemically synthesized polystyrene or silica particles. We investigated the neighbour distribution in a two-dimensional polydisperse harddisk fluid, corresponding physically to a colloidal monolayer. The disk diameter distribution was defined by a power-law with the aim of realizing a scale-free nearneighbour network. Scale-free (power-law) behaviour is found in many important networks, for example, in transportation systems, biochemical reactions, scientific and movie-actor collaborations, and sexual contacts. We have provided the first example of a scale-free network in amodel condensed-matter system. Finally, we use genetic algorithms, a method for efficiently searching for minima on energy landscapes, to investigate the ordered equilibrium structures formed by binary mixtures of anisotropic dipolar particles confined on a plane, under the presence of an external magnetic field. The anisotropy of the interparticle forces is controlled by tilting the external magnetic field with respect to the plane. Initially, as the field is tilted the structures are only slightly perturbed, but once the anisotropy exceeds a critical value, completely new structures emerge.
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Jahn, S. "Polymer-driven colloidal self-assembly." Thesis, University of Cambridge, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.605018.
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In this thesis, we used an experimental approach to study the self-assembly of colloids driven by a bio- or synthetic polymer. We investigated three different systems: (1) Micrometer-sized polystyrene colloids were coated with very long phage-DNA and examined in the presence of protein-multilayers and weakly attractive poly-L-lysine poly (ethylene glycol) surfaces modified with and without short single-stranded DNA. We observed the formation of 2D crystals several micrometers above all surfaces as well as a difference in “flying height” of the crystals depending on the surface coating. Once formed, the crystals remained stable over weeks at various ionic strengths. A factor identified to play a major role in the formation of crystals is colloidal polydispersity. (2) We studied the behaviour of negatively charged, non-adsorbing, bare silica microspheres on “soft” substrates. Surface-grafted thick DNA brushes were compared to polyacrylamide hydrogels of varying rigidity. The evolution of 2D square-lattices in coexistence with hexagonally ordered structures surrounded by a dilute colloidal gas above soft surfaces was identified. This observation appears to be due to an attractive interaction based on the elastic deformation of the substrate caused by the colloids independent of the nature of the support substrate. For substrates with elastic moduli above a certain threshold, we observed no ordering. (3) We used superparamagnetic iron oxide nanoparticles grafted with thermo-responsive co-polymers of distinct molar fractions to demonstrate the reversible agglomeration in aqueous media and inside cellular microcompartments. The agglomeration led to a significant contrast enhancement in T2*-weighted MRI imaging. We developed and optimised a hypo-osmotic dilutional method to incorporate the particles into Red Blood Cells to evaluate their biocompatibility and suitability as long-circulating contrast agents and drug delivery devices.
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Sagar, Rajeeve. "Self-assembly via hydrogen bonding." Thesis, University of Warwick, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.247352.
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Schergna, Stefano. "Self assembly of interlocked architectures." Thesis, University of Warwick, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.252501.
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Razali, Azaima. "Self assembly in gel systems." Thesis, University of Bristol, 2018. http://hdl.handle.net/1983/77bc44c6-4aed-4548-90f6-4c2f6975e522.
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In this work we have studied the structural evolution of colloid polymer system reaching equilibrium ordered states. Throughout the work in this thesis, confocal microscopy was primarily used to capture the local structural changes. We employed the depletion mechanism from the addition of nonadsorbing polymer to colloidal dispersion in order to obtain short ranged attractive systems. The changes of local structures towards crystallisation in the colloid polymer systems are analysed using topological cluster classification (TCC), common neighbour analysis (CNA) and bond order parameter ψ6. Initial work studies the ageing of gels with different interaction strengths in experiment and simulation. Structural analysis of the gels shows significant similarity between experiment and simulation. In both, we find crystallisation in gels with intermediate interaction strength and formation of five-fold symmetry clusters in gels with higher interaction strengths. Then we examine the effects of confinement to the sedimentation of colloids and gels. We find that gelation enhances sedimentation of colloids whereas there is no sedimentation in a same system without polymer. The structural analysis of the simulation results show that the local structural changes is not related to sedimentation. By manipulating the polymer response to temperature, we change the interaction strength in the colloid polymer system in order to obtain better crystallisation. This work is based on the idea from simulation work [1], where tuning the interaction strengths during self assembly leads to better and larger ordered structures. However, contrary to the simulation results, we find that tuning the interaction strengths result to disruption to the crystallisation pathway thus more disordered structures is formed.
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Fejer, Szilard. "Self-assembly in complex systems." Thesis, University of Cambridge, 2009. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.611771.
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Leckie, Joy Susan. "Nanopropulsion by biocatalytic self-assembly." Thesis, University of Strathclyde, 2015. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=25502.
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In nature, a number of organisms and organelles are capable of self-propulsion at the micro- and nano-scale. Inspired by biological motors, this investigation aims to induce self-propulsion of an enzyme, by the biocatalytic self-assembly of aromatic peptide amphiphile molecules into supramolecular fibre structures. The individual motion of enzymes is measured directly using fluorescence microscopy, by the covalent attachment of alkaline phosphatase to fluorescing quantum dots. Enzyme-quantum dot conjugates represent nanoparticulate ‘vehicles’ transported by the enzyme 'motor'. Two aromatic peptide substrate ‘fuels’, initially assembled in a micellar form, are studied for their ability to propel enzyme-quantum dot conjugates, by biocatalytic dephosphorylation causing self-assembly into one-dimensional fibres. The effect of the ‘fuel’ on conjugate motion is compared with controls consisting of no fuel, a non-self-assembling substrate and a non-directional self-assembling substrate (i.e. one that assembles into spheres, but not fibres). Significant quantities of data were obtained for each substrate scenario and speed distribution plots revealed that enzyme-conjugates exhibit faster transport with the fibre forming system, compared to controls. Further to this, upon increasing the concentration of the fibre-forming fuel, the average speed of the conjugates increases, although directionality remains random. An initial investigation for directional control is carried out using 'fuel' reservoirs consisting of substrate saturated polyacrylamide gels. Substrates diffuse from the gel into surrounding motility medium creating a concentration gradient, which the enzyme-motors are proposed to travel along in a directional manner. The proposed propulsion model for self-assembly-driven motion of enzyme-conjugates is that short bursts of fibre growth provides linear propulsion which increases the diffusion rate of the enzyme-conjugate. Simultaneous visualisation of self-assembled fibres and enzyme-quantum dot conjugates is attempted, using extrinsic and intrinsic fluorescent methods, to investigate the mechanism proposed for fibre-propulsion. Finally, enzymes thermolysin and α-chymotrypsin are investigated as a step toward generalising the method for other enzymes and for their potential use in a multi-enzyme/multi-coloured quantum dot system for future applications in nano-separation of enzymes.
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Kwiecinski, James Andrew. "Self-assembly in mechanical systems." Thesis, University of Oxford, 2018. http://ora.ox.ac.uk/objects/uuid:a3b521ad-be4a-4152-aaa6-f9a002060c48.
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Inspired by biological membrane shaping in the cell through means of curvature-inducing proteins, we investigate the interplay between membrane curvature and the distribution and movement of shape-inducing objects which are free to move as a consequence of the underlying shape. We initially study the self-assembly of a filament, taken as a proxy for the cross-section of a biomembrane, which is primarily driven by the chemical kinetics of attaching proteins and find that, under certain mechanical stiffness regimes of the attaching proteins, pattern formation occurs. Regions of high and low protein concentration form before spatially uniform filament shapes are obtained by means of protein adhesion and movement governed by diffusion and local curvature-seeking. However, noting that the curvature-mediated protein movement on membranes has been biologically observed to be long-range, we next study the self-assembly of embedded inclusions on a membrane as a result of the underlying geometry. We first derive an interaction law for the shape-mediated interaction of inclusions which break symmetry and find that there is a finite equilibrium distance to which the inclusions will aggregate. We derive corresponding equations of motion which describe this curvature-mediated aggregation mechanism and, using this framework, we investigate some of the properties of these self-assembled configurations, including their energy, stability, and their collective elastic behavior. Lastly, we consider the interaction energies of embedded inclusions on a periodic domain and determine that this mechanism may explain computational results of how proteins form rings to promote tubulation on cylindrical membranes.
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Ющенко, Ольга Володимирівна, Ольга Владимировна Ющенко, Olha Volodymyrivna Yushchenko, Анна Юріївна Бадалян, Анна Юрьевна Бадалян, Anna Yuriivna Badalian, and S. O. Bratash. "A self-assembly of nanoparticles." Thesis, Sumy State University, 2014. http://essuir.sumdu.edu.ua/handle/123456789/39629.
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Nanotechnology achievements are often connected to material science because the design of a wide range of advanced nanostructured materials will reduce the size of the components of many devices. But nanoscience
today is more interested in the formation of nanoassemblies and further coupling of them into the nanostructured materials.
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Falk, Martin Jin-teng. "Self-assembly of biological heteropolymers." Thesis, Massachusetts Institute of Technology, 2020. https://hdl.handle.net/1721.1/128325.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Physics, February, 2020Cataloged from PDF version of thesis.
Includes bibliographical references (pages 115-122).
In this thesis, we are primarily concerned with understanding the complicated geometrical and topological structures that polymers can adopt. We first consider this in the context of chromatin, the polymer of DNA and associated proteins. Our experiments and coarse-grained modeling suggest that attractions between heterochromatic regions are central to the separation of the active and inactive genome in nuclei. We adopt a similar strategy of coarse-grained polymer modeling in order to devise a collagen-like scheme for twisting polymers together. We found that such scheme generically includes the presence of defects, which we speculate could be useful in designing hierarchical assemblies of twisted filaments. In order to extend strategies for twisting of filaments to arbitrary braid topologies, we constructed a simple numerical model for a device that manipulates float-attached wires with capillary interactions between the walls of the device and the float. We use this model to rationalize design rules for the device, and to predict the motion of the float in non-trivial geometries. Finally, we study the dynamics of a two-dimensional seven-particle cluster as it relaxes from an extended, polymer-like state. We find that this system rarely reaches its (non-degenerate) global free energy minimum.
by Martin Jin-teng Falk.
Ph. D.
Ph.D. Massachusetts Institute of Technology, Department of Physics
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Luhrs, Chris. "Producing reliable nanoscale self-assembly /." May be available electronically:, 2008. http://proquest.umi.com/login?COPT=REJTPTU1MTUmSU5UPTAmVkVSPTI=&clientId=12498.
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Li, Xuehe. "Self-assembly, Templation and biomimetics." ScholarWorks@UNO, 2002. http://louisdl.louislibraries.org/u?/NOD,25.
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Thesis (Ph. D.)--University of New Orleans, 2002.Title from electronic submission form. Vita. "A dissertation ... in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the Department of Chemistry"--Dissertation t.p. Includes bibliographical references.
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Spiteri, Ludovic. "Self-assembly of dipolar particles." Thesis, Université de Lorraine, 2018. http://www.theses.fr/2018LORR0261/document.
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Cette thèse couvre l'auto-assemblage de particules dipolaires (magnétiques/électriques). Ces systèmes sont abondants en physique de la matière condensée (molécules et nanoparticules magnétiques, particules colloïdales magnétiques, bactérie magnétotactique, etc.). Sur un plan fondamental, ils représentent un défi important en raison de l'anisotropie et de la longue portée de l'interaction de paire. Le principal objectif de ce travail de recherche est de prédire les microstructures de ces systèmes en tenant compte de façon adéquate de l'interaction complexe dipôle-dipôle ainsi que des effets stériques et ceux dus à un éventuel confinement. Comprendre et revisiter les interactions de filaments dipolaires tels que des aiguilles et des chaînes faites de billes dipolaires est une première étape importante de cette thèse. En effet, les chaînes sont les constituants élémentaires de nombreux systèmes dipolaires, notamment sous l'effet d'un champ magnétique extérieur appliqué. Ensuite, l'agrégation colonnaire des chaînes dipolaires est examinée, ce qui conduit aussi naturellement à l'étude des cristaux dipolaires massifs où une nouvelle phase est découverte. Le cas plus générique des chaînes hélicoïdales est discuté en considérant les situations limites que sont les chaînes linéaires droites et en zigzag. L'association des chaînes dipolaires, dans le cas bidimensionnel, forme des rubans, puis une monocouche avec un réseau hexagonal. La réponse non triviale d'un tel réseau à un champ magnétique perpendiculaire imposé est aussi étudiée. Il est démontré qu'un réseau rhombique peut être induit de cette façon. Finalement, la sédimentation de particules paramagnétiques dans une monocouche inclinée en présence d'un champ magnétique est explorée via une étude mêlant expériences, théorie et simulations. L'ordre induit par gravité s'avère être une voie prometteuse pour l'élaboration contrôlée de réseaux bidimensionnelsThis thesis covers the self-assembly of dipolar (magnetic/dielectric) particles. These systems are abundant in condensed matter physics (magnetic molecules and nanoparticles, magnetic colloidal particles, magnetotactic bacteria, etc). They also represent a fundamental challenge owing to the both long range and anisotropic nature of the pair interaction. The main objective of this research work is to predict the microstructures of these systems by properly handling the intricate dipole-dipole interaction combined with steric and possibly confinement effects. Understanding and revisiting the interaction of dipolar filaments such as needles or chains made up of dipolar beads is a first important achievement in this thesis. Indeed, the chains are the fundamental building blocks of many dipolar systems especially under applied external magnetic field. Then, the columnar aggregation of dipolar chains is investigated which naturally leads to the study of the bulk dipolar crystals. A new phase is discovered there. The more generic case of helical chains is discussed by considering limiting situations such as straight linear chains and zigzag chains. The association of dipolar chains in two-dimensions forms ribbons then a monolayer with triangular lattice symmetry. The interesting response of such a layer to an imposed perpendicular magnetic is addressed as well. It is demonstrated that rhombicity can be induced that way. Finally, sedimenting paramagnetic particles in a tilted monolayer in presence of a magnetic field are investigated by experiments, theory and simulations. The gravity-mediated ordering is found to be a promising route to elaborate tailored two-dimensional patterns
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Spiteri, Ludovic. "Self-assembly of dipolar particles." Electronic Thesis or Diss., Université de Lorraine, 2018. http://www.theses.fr/2018LORR0261.
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Cette thèse couvre l'auto-assemblage de particules dipolaires (magnétiques/électriques). Ces systèmes sont abondants en physique de la matière condensée (molécules et nanoparticules magnétiques, particules colloïdales magnétiques, bactérie magnétotactique, etc.). Sur un plan fondamental, ils représentent un défi important en raison de l'anisotropie et de la longue portée de l'interaction de paire. Le principal objectif de ce travail de recherche est de prédire les microstructures de ces systèmes en tenant compte de façon adéquate de l'interaction complexe dipôle-dipôle ainsi que des effets stériques et ceux dus à un éventuel confinement. Comprendre et revisiter les interactions de filaments dipolaires tels que des aiguilles et des chaînes faites de billes dipolaires est une première étape importante de cette thèse. En effet, les chaînes sont les constituants élémentaires de nombreux systèmes dipolaires, notamment sous l'effet d'un champ magnétique extérieur appliqué. Ensuite, l'agrégation colonnaire des chaînes dipolaires est examinée, ce qui conduit aussi naturellement à l'étude des cristaux dipolaires massifs où une nouvelle phase est découverte. Le cas plus générique des chaînes hélicoïdales est discuté en considérant les situations limites que sont les chaînes linéaires droites et en zigzag. L'association des chaînes dipolaires, dans le cas bidimensionnel, forme des rubans, puis une monocouche avec un réseau hexagonal. La réponse non triviale d'un tel réseau à un champ magnétique perpendiculaire imposé est aussi étudiée. Il est démontré qu'un réseau rhombique peut être induit de cette façon. Finalement, la sédimentation de particules paramagnétiques dans une monocouche inclinée en présence d'un champ magnétique est explorée via une étude mêlant expériences, théorie et simulations. L'ordre induit par gravité s'avère être une voie prometteuse pour l'élaboration contrôlée de réseaux bidimensionnelsThis thesis covers the self-assembly of dipolar (magnetic/dielectric) particles. These systems are abundant in condensed matter physics (magnetic molecules and nanoparticles, magnetic colloidal particles, magnetotactic bacteria, etc). They also represent a fundamental challenge owing to the both long range and anisotropic nature of the pair interaction. The main objective of this research work is to predict the microstructures of these systems by properly handling the intricate dipole-dipole interaction combined with steric and possibly confinement effects. Understanding and revisiting the interaction of dipolar filaments such as needles or chains made up of dipolar beads is a first important achievement in this thesis. Indeed, the chains are the fundamental building blocks of many dipolar systems especially under applied external magnetic field. Then, the columnar aggregation of dipolar chains is investigated which naturally leads to the study of the bulk dipolar crystals. A new phase is discovered there. The more generic case of helical chains is discussed by considering limiting situations such as straight linear chains and zigzag chains. The association of dipolar chains in two-dimensions forms ribbons then a monolayer with triangular lattice symmetry. The interesting response of such a layer to an imposed perpendicular magnetic is addressed as well. It is demonstrated that rhombicity can be induced that way. Finally, sedimenting paramagnetic particles in a tilted monolayer in presence of a magnetic field are investigated by experiments, theory and simulations. The gravity-mediated ordering is found to be a promising route to elaborate tailored two-dimensional patterns
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Karpenko, Daria. "Self-assembly of Self-similar Structures by Active Tiles." Scholar Commons, 2012. http://scholarcommons.usf.edu/etd/4095.
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The natural capacity of DNA for molecular self-assembly has already been exploited to create DNA based tiles which can self-assemble into nano-scale arrays and carry out nano-scale computation. Thus far, however, all such self-assembly has been passive, in the sense that the binding capacities of a tile are never altered throughout the assembly. The idea of active tiles, tiles that can send signals to each other and activate latent binding sites, has been proposed but never incorporated into a formal model. Here, I present an extension of the existent abstract tile assembly model by defining an active tile assembly and give a detailed example of an aperiodic set of active tiles which hierarchically produces a self-similar L-shape tiling. This yields a technique utilizing active tiles for the assembly of aperiodic self-similar shapes.
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Guldin, Stefan. "Inorganic nanoarchitectures by organic self assembly." Thesis, University of Cambridge, 2014. https://www.repository.cam.ac.uk/handle/1810/245290.
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Montgomery, Caroline Beryl. "The self-assembly of diphenylalanine fibres." Thesis, University of Warwick, 2015. http://wrap.warwick.ac.uk/77370/.
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The diphenylalanine (FF) dipeptide is the core recognition motif of the Alzheimer’s amyloid beta (Aß) polypeptide, as well as being important in other amyloidogenic proteins. The Aß polypeptide self assembles to form fibrils and these fibrils are found in the brains of patients with Alzheimer’s disease. FF itself is also known to self-assemble to form fibres and there has been much interest in the FF motif since Reches and Gazit made this observation. The structures it forms are biocompatible and have a high aspect ratio. Under different conditions of humidity and concentration it can form various morphologies such as nanovesicles and ribbons. Despite the great interest in this area, the self-assembly mechanism of these fibres is not known. The motivation throughout this work has been to understand the assembly of the elongated FF fibres in order to be able to control it for the variety of applications that have been suggested. Several experimental and theoretical techniques were used to this end. Molecular and metadynamics simulations were employed to investigate the early stages of the fibres assembly. Optical spectrocopy was used to investigate their assembly kinetics and mechanism in situ. New linear dichroism (LD) methods were developed in order to study the FF fibres which grow into large rigid structures. A new electronic LD sequencer was created which made it possible to automate kinetics measurements over long periods of time, and a new capillary was designed and built which could be cleaned more thoroughly than the previous models. These experiments showed that FF fibres assemble by nucleation driven assembly, with secondary nucleation taking place. They also showed that 40 °C is an important temperature in the onset of fibre formation. Electron and optical microscopy were used to quantify the heterogeneity of the fibres and to observe their growth in real time. It was found that the fibres were more heterogenous than had previously been reported. The results of these experiments elucidated new information about the characteristics and the self-assembly of FF fibres, as well as developed techniques in order to probe them, and similar biological fibres, further.
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Vigier-Carriere, Cécile. "Surface assisted self-assembly of peptides." Thesis, Strasbourg, 2016. http://www.theses.fr/2016STRAE013/document.
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Depuis quelques années, la modification de surface est une méthode efficace qui permet de contrôler les interactions entre un matériau et son environnement. Ce domaine de recherche ouvre la voie au développement de nouvelles surfaces « intelligentes » aux propriétés fonctionnelles. Dans ce manuscrit, nous présentons la conception d’un revêtement capable de contrôler l’auto-assemblage de peptides exclusivement à la surface d’un matériau. L'auto-assemblage est initié par un stimulus enzymatique localisé à la surface qui permet la transformation de peptides précurseurs en peptides gélateurs, ayant la propriété de s’auto-assembler pour former des structures fibrillaires enchevêtrées pour former un hydrogel. Les surfaces enzymatiques ont été obtenues par adsorption d’enzyme spécifique en utilisant la méthode « couche par couche ». Dans une première approche, la croissance du réseau de fibres est initiée par accumulation d’oligopeptides (KL)nOEt confinés sur un film enzymatique d’α-chymotrypsine. Ce processus d’hydrogélation peut être contrôlé dans le temps (en ajustant le temps de latence) en changeant la concentration en peptides KLOEt et la densité de surface en enzyme. Dans une deuxième approche, le film multicouche bioactif contenant l’alcaline phosphatase a été fonctionnalisé par une couche d’ensemencement composée d’acide poly(acrylique) modifié par une séquence peptidique Fmoc-FFC aux propriétés gélatrices. La modification de la densité de peptides gélatrices en surface a permis de contrôler le processus d’auto-assemblage du peptide gélateur Fmoc-FFY depuis la surface. Lorsque le film bioactif est mis en contact avec le peptide précurseur, i.e. Fmoc-FFY(PO42-) substrat de l’alcaline phosphatase, le peptide gélateur se forme et s’auto-assemble sous forme de nanofibres à partir de la surface. Grâce à ces deux études nous avons démontré qu'un film précurseur enzymatique ou une couche bioactive d'ensemencement sont des matériaux permettant d’initier et de contrôler l’auto-assemblage de peptides en surface afin de former un hydrogelSince the middle of the last century, the functionalization of surfaces has emerged as a convenient method to control interactions between a material and its surrounding environment. This recent research field paves the way to the design of surfaces bearing original “smart” functionalities. Herein, we present the design and control of peptide self-assembly taking place exclusively at or near a surface in response to an enzymatic stimulus. The localized enzyme-assisted self-assembly (LEASA) of peptides led to the growth of micrometric hydrogels from the surface. The enzymatic surface was obtained by adsorption of specific enzymes using the layer-by-layer method. In a first strategy, we developed the growth of fibrillary networks resulting from the accumulation of oligopeptides (KL)nOEt produced from a confined enzymatic layer of α-chymotrypsine at the interface. This process of gelation was tuned in time (lag time) by controlling the peptide KLOEt concentration and the enzymatic surface density. In a second strategy, alkaline phosphatase was embedded into a multilayer film to obtain a bioactive surface on which a seed-layer, i.e a poly(acrylic acid) covalently modified with a hydrogelator peptide, was adsorbed. This layer allows to control the self-assembly of the fiber network by changing the peptide density anchored on the seed layer. When this bioactive and seeding film is brought into contact with the peptide substrate, i.e. Fmoc-FFY(PO42-), of alkaline phosphatase, an efficient self-assembly of Fmoc-FFY is obtained leading to nanofibers growing from the surface. We demonstrated that an enzymatic precursor film or a more sophisticated bioactive seeding layer can self-instruct the self-assembly of small peptides sequences and influence buildup of a micrometric hydrogel from the surface
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Hall, Jeffrey Ronald. "The self-assembly of metallosupramolecular architectures." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1996. http://www.collectionscanada.ca/obj/s4/f2/dsk2/ftp04/MQ30907.pdf.
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Solomon, Matthew Daniel. "Laterally driven self-assembly of microstructures." Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.272242.
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Cheng, S. "Improved nanofiltration membranes by self-assembly." Thesis, Swansea University, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636243.
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Charged ultrafiltration (UF)/nanofiltration (NF) membrane plays a very important role in membrane separation. Thus, the aim of the present study was to improve charged UF and NF membranes for increased application within the process, pharmaceutical and food industries. The main objectives of this work were to investigate the preparation, modification, characterisation and application of a group of charged UF/NF membranes. Substrate membranes were prepared with polyehterimide (PEI) and sulfonated poly(ether ether ketone) (SPEEK). The self-assembly deposition of polyelectrolytes on the membrane surface was also studied. No previous studies have so comprehensively assessed the fabrication and performance of self-assembly modified PEI/SPEEK membranes. The effects of small molecular additives were studied on membrane morphology and performance. Characterisation by scanning electron macroscopy (SEM) and atomic force macroscopy (AFM) showed that the addition of tetrahydrofuran (THF) and 1,4-dioxane induced a denser skinned top layer, which dramatically decreased the permeability. SPEEK was used to improve the hydrophilic properties of PEI membrane and permeability, as well as to provide surface charges. The membrane properties were very reproducible when the proportions of SPEEK were 3% and 6% in the total polymer content. Positively and negatively charged NF membranes were fabricated by self-assembly. Positive NF membrane was obtained by depositing polycation, polyethylenimine, on the surface of PEI/SPEEK blend membranes. The effects of Ph and ionic strength of the polyelectrolyte solution on the membrane performance were investigated and it was concluded that the high amount of adsorption of weak polyelectrolyte on the membrane surface with opposite charges was achieved close to the isoelectric point (IEP). Again, negatively charged NF membrane was fabricated by depositing poly (acrylic acid) (PAA) on the surface of positively charged membranes. Zeta potential measurements showed that the deposition of polyelectrolytes changed chemistry of the membrane surfaces. The pore sizes calculated from rejection data using and from AFM demonstrated that the adsorption of polyelectrolytes on membrane surfaces led to the decrease of pore size. The present study has shown the advantage of using phase imaging to characterise membrane morphology; the identification and sizing of pores was easier than when using standard topography. No other studies have used this technique to study pore sizes. Methylene blue (MB) and sodium cefuroxime were used to explore the industry application of obtained membranes.
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Carew, Daniel B. "Self-assembly of soft nanostructured materials." Thesis, University of Bristol, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.664972.
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This thesis describes the design and characterisation of self-assembled systems that employ Coulombic interactions as the primary means for driving assembly. Hierarchical self-assembly is sought in three different areas: mesoporous materials, two-dimensional polymers, and peptide fibres. Chapter 1 presents a general introduction to the rationale for using self-assembly to achieve nanotechnology, the basic principles of self-assembly, and an introduction to charge-based assembly, mesoporous materials, two dimensional polymers, and peptide fibres. Chapter 2 describes a new method to synthesise mesoporous membranes, which may contain silica, using ionic self-assembly. These materials result from combining polyelectrolytes with surfactants and inorganic precursors at liquid-liquid interfaces to give a columnar structure perpendicular to their surface. Chapter 3 describes the theoretical design requirements for a tecton that assembles to form a two-dimensional self-assembled polymer. Based on these rules a peptide-based building block is designed, synthesised, and characterised along with the resulting two-dimensional sheets. Chapter 4 continues the topic of 20 polymers with two next-generation systems for studying the assembly of two-dimensional peptide sheets. Chapter 5 describes research towards achieving hierarchical assembly with Self-Assembled Peptide Fibres using layer-by-layer self-assembly and electrophoretic deposition
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Young, Michael Christopher. "Self-Assembly of Functionalized Supramolecular Structures." Thesis, University of California, Riverside, 2014. http://pqdtopen.proquest.com/#viewpdf?dispub=3644049.
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Enzymes are capable of exquisite selectivity in catalysis chemical reactions because of a well-evolved mechanism that binds substrates in internal active sites based on size and shape complementarity. The cavities of these enzymes are decorated with organic or inorganic groups which can promote reactivity once the substrate is non-covalently bound. Synthetic molecular hosts to date have been able to bind to substrates in a similar, biomimetic fashion, but functionalized molecular hosts are still virtually unknown.
One convenient way to prepare molecular hosts is by the self-assembly of organic coordinating ligands with suitable metal salts. The reversible dative bonds holding these cage structures together allow incorrect products to break apart and reform, favoring creation of the most thermodynamically stable product. This leads to discrete, solution phase cages that can function as cavity-containing hosts. Some of these hosts have shown efficacy as catalysts for pericyclic reactions due to favorable transition states of the bound substrates. These cages, however, fail to orient reactive functional groups into their interiors. Truly biomimetic cages will require modifying traditional self-assembled targets to incorporate these reactive functionalities.
This work explores the self-assembly of metal-organic cages displaying covalent modifications on their interior. Incorporation of unreactive and poorly reactive groups was found to have a significant impact on the outcome of the self-assembly process. Cages with endohedral alcoholic functionality were found to have different binding properties than unfunctionalized analogs. Cages with introverted alcohol groups were also exploited for their ability to self-catalyze reactions on the interior of the hosts. The metal vertices themselves could also be used as functional groups, and showed the ability to sense neutral analytes in hybrid dative/hydrogen bonded self-assemblies.
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Syafitri, Niken. "Self-organising assembly using swarm robots." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/418969/.
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When a swarm of small robots is required to operate in an unstructured and unknown environment, adaptability is required, particularly in the case of traversing a void (typically a crevasse or gap between two stable platforms). Adaptability is required when robots face a void of an unknown size so that they can safely cross. By applying adapt- ability, the robustness of the swarm can be maintained either by crossing a void or safely retreating after failing to cross. However, the relatively simple characteristics of swarm robots limit their performance in a complex task when they work individually, but it can be accomplished when they work collaboratively. Solving the problem arised, a strategy of self-organising assembly has been proposed supported by simulation and practical experiments. Algorithms with simple rules have been developed that allows the robot swarm to reach the target area from an initial zone separated by the void, where the size and location of the void are unknown. The configuration for the dynamic structure have been proposed built by the robot swarm to bridging two separated zones. To measure the performance of the swarm, metrics have been identified within the simulation environment. A number of 3D printed platforms have been designed and evaluated to investigate the emerging physical problems including the required docking system, platform shape, approaches to actuation and communication system. Several contributions have been achieved, in particular the approach that proposes a dynamic structure with simple rules that is constructed by a robotic swarm to cross the void, where the size and location of the void are unknown. This is in accordance with the concept of self-organise and self-assembly. The solution developed is scalable, with any number of robots can be added into the swarm. Any robot can also be the leader who initiates the construction or detects the target. When the size of the swarm does not satisfy with the size of the void, the swarm will retreat to the initial zone to prevent the robots lost. To support the rigid dynamic structure, a number of docking mechanisms are proposed.
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Pinto, Vieira Vânia Margarida. "Orthogonal self-assembly of bioactive hydrogels." Thesis, University of York, 2017. http://etheses.whiterose.ac.uk/19305/.
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Hydrogels are of great interest due to their ability to encapsulate and deliver bioactive molecules, mimic the extracellular matrix (ECM) and act as an artificial 3D scaffold. Here we report multi-component hydrogels based on low-molecular-weight gelators (LMWGs) and polymer gelators (PGs) incorporating heparin that can bind to self-assembled molecules, and their potential for controlled release and to mimic the ECM. These multi- component systems were characterised and the orthogonality of each individual component investigated. Firstly, three cationic surfactants were synthesised and their ability to self-assemble and bind to polyanionic heparin was investigated. The systems consisted of an amine-based head group connected via an amide linkage to different saturated fatty acids. Self- assembled C14-DAPMA and C16-DAPMA formed highly organised polycrystalline assemblies with heparin, proving that the micelles remain intact during the hierarchical assembly process. C16-DAPMA proved to be the most charge-efficient heparin binder, also with the lowest critical aggregation concentration, with high stability when free and solution and when electrostatically interacting with heparin. Two dibenzylidene-D-sorbitol (DBS) derivatives capable of forming hydrogels are then introduced: a pH-activated LMWG (DBS-COOH) and a thermally-activated LWMG (DBS- CONHNH2). The incorporation and release of heparin from the LMWGs hydrogels in the presence and absence of C16-DAPMA, and from hybrid hydrogels consisting of one of the LMWGs and a PG - agarose is reported. The rate of heparin release can be controlled through network density and composition, and control of the release surface area to volume ratio, while the presence of C16-DAPMA inhibits heparin release. Characterisation of this multi-component complexes (LMWG + Heparin + C16-DAPMA) showed the orthogonal self-assembly of each individual component within one single system. Cytocompatilibity of the multi-component hydrogels is reported. Heparin was then incorporated and released from three different hydrogels based on triamide cyclohexane derivatives. From these, a positively charged LMWG able to directly interact with heparin, resulted in the triggered release of heparin by hydrogel disruption through enzymatic cleavage.
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Do, Hyung Wan. "Computation by block copolymer self-assembly." Thesis, Massachusetts Institute of Technology, 2018. http://hdl.handle.net/1721.1/117840.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2018.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.
Cataloged from student-submitted PDF version of thesis.
Includes bibliographical references.
Unconventional computation is a paradigm of computation that uses novel information tokens from natural systems to perform information processing. Using the complexity of physical systems, unconventional computing systems can efficiently solve problems that are difficult to solve classically. In this thesis, we use block copolymer self-assembly, a well-studied phenomenon in polymer science, to develop a new approach to computing by applying directed self-assembly to implement Ising-model-based computing systems in materials. In the first part of the thesis, we investigate directed self-assembly of block copolymer thin films within templates of different polygonal shapes. We define a two-state system based on the two degenerate alignment orientations of the ladder-shaped block copolymer structures formed inside square confinements, and study properties of the two-state system. In the second part of the thesis, we demonstrate an Ising lattice setup for directed self-assembly of block copolymers defined on two-dimensional arrays of posts. We develop an Ising-model-based simulation method that can perform block copolymer pattern prediction and template design. Finally, we design simple Boolean logic gates as a proof-of-concept demonstration of computation.
by Hyung Wan Do.
Ph. D.
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Aimon, Nicolas M. "Templated self-assembly of multiferroic nanocomposites." Thesis, Massachusetts Institute of Technology, 2014. http://hdl.handle.net/1721.1/89948.
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Thesis: Ph. D., Massachusetts Institute of Technology, Department of Materials Science and Engineering, 2014.Cataloged from PDF version of thesis.
Includes bibliographical references (pages 133-150).
To respond to the growing demand for smart and connected devices, such as smartphones, tablet PCs arid other mobile hardware, while meeting the needs for increased power efficiency, miniaturization and reduced manufacturing costs, new material solutions need to be considered. These should address the shortcomings of incumbent semiconductor-based technologies which provide a limited number of functionalities, suffer from high power consumption and heat dissipation, and whose conventional planar processing is increasingly complex and resource-intensive. Potential replacement materials include complex oxides, which exhibit interesting physical phenomena such as superconductivity, colossal magnetoresistance and multiferroicity. New functionalities are especially found at interfaces between two oxides, including emergent electronic states like two-dimensional electron gases, enhanced ionic transport and magnetoelectric coupling, among many other. In this this thesis, we focus on self-assembled oxide nanocomposites, which elegantly organize into vertical nanostructures via spontaneous phase-separation, naturally forming numerous such heterointerfaces. These provide a rich playground for studying interfacial effects, which could be used in future devices, and the self-assembly promises cheap arid high throughput manufacturing providing it can be integrated into useful architectures. BiFeO₃-CoFe₂O₄ self-assembled nanocomposites, in particular, have been studied for the magnetoelectric coupling that takes place between the ferrimagnetic spinel phase, which forms discrete vertical pillars, arid the ferroelectric perovskite phase, which forms a matrix that surrounds the spinel pillars. Here, after an in-depth study of the mechanisms responsible for the formation of this self-assembled nanostructure, we develop a templating method enabling the precise control over the morphology of the film, resulting in useful structures for potential devices like magnetoelectric memories and logic devices. To study the structural, magnetic and electrical properties of our samples, a set of experimental and theoretical methods is developed, adapted to the unique requirements of these thin film nanostructures with iicron-scale ordering. Using finite element analysis and micromagnetic modeling, the effect of the strain-mediated magnetoelectic coupling on the magnetic switching of the CoFe₂O₄ nanopillars is predicted. Scanning Probe Microscopy is also used to characterize the local ferroelectric and magnetic behavior, and observe, for the first time in these templated composites, electrically-induced magnetic switching of the pillar magnetization. The tools and methods developed in this thesis could pave the way towards a wider use of templated self-assembly to leverage the promising properties of oxide heterointerfaces and enable their use in future devices with low manufacturing costs.
by Nicolas M. Airmon.
Ph. D.
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Fujii, Jennifer T. (Jennifer Tomiko) 1972. "Multicellular self-assembly on patterned surfaces." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/8826.
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Thesis (Ph.D.)--Massachusetts Institute of Technology, Dept. of Chemical Engineering, 2000.Includes bibliographical references.
Controlling the spatial distribution of cells in two and three dimensions may be important in the design of advanced tissue engineering scaffolds and other biomedical applications. In this thesis, the concept of biophysical sorting was applied as a method to control the spatial distribution of cells. This approach relies on a self-assembly process that is dependent, in part, on the intrinsic adhesivity of cells. A model system was developed using a simple patterning technique to prepare surfaces with alternating regions that supported variable cell response. First, the influence of certain biophysical parameters that may govern multicellular assembly of a single cell type on patterned surfaces was quantitatively investigated. For surfaces patterned with small features that allow cells to sample surrounding regions through membrane protrusions, it was found that a dynamic equilibrium distribution of cells correlated with differen~es in cell-substratum adhesion strength. The approach to that distribution, however, could be kinetically limited by the inability of the individual cells to sample adjacent areas of the patterned surface. This kinetic limitation was studied on surfaces with increasingly large feature sizes, and found that a simple diffusion model of migration may not completely describe the present system. Other effects such as contact inhibited motility and an induction time for migration may also influence multicellular assembly. The potential of multicellular assembly to simultaneously control the distribution of two cell types was also investigated. First, the multicellular assembly of each cell type was studied in isolation. Co-culture experiments indicated that, in addition to the factors that govern the assembly of a single cell type, sorting of two cell types depended on cell density. Images of high cell density co-cultures suggest that incomplete biophysical separation was achieved.
by Jennifer T. Fujii.
Ph.D.
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Au, Hin Meng 1977. "Solder self-assembly for MEMS fabrication." Thesis, Massachusetts Institute of Technology, 2004. http://hdl.handle.net/1721.1/30304.
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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Mechanical Engineering, 2004.Includes bibliographical references (leaves 99-100).
This thesis examines and demonstrates self-assembly of MEMS components on the 25 micron scale onto substrates using the capillary force of solder. This is an order of magnitude smaller than current solder self-assembly in the literature. This thesis also examines self-assembly of high aspect ratio (2:1) microfabricated structures, which poses a greater challenge in terms of alignment and orientation compared to self-assembly of flat structures. The goal of the assembly is to construct a DEP-based cell trap, which consists of sets of high aspect ratio conducting posts on a Pyrex substrate, along with electrical connections to the posts. The posts and substrates are fabricated separately and then combined together through a self-assembly process. The posts are made of silicon and are 25 Im in diameter and 50 plm tall with a thin gold cap on one end to serve as a wetting site. The substrates are Pyrex wafers which are patterned with arrays of binding sites and electrical connections, and selectively coated with a low melting point bismuth solder alloy on the binding sites. Self-assembly of the posts onto the substrate is then driven by the free surface energy minimization of solder when the gold-capped ends of the silicon posts come into contact with the solder bumps. In this project, self-assembly has been successfully demonstrated with a yield of about 50%.
(cont.) However, it also becomes increasingly difficult to control component placement and orientation at these small size scales, because deviations in components and sites from their ideal geometries become relatively pronounced as feature size is reduced. It is observed that post concentration, agitation, and solder wetting of the substrate and posts binding sites are critical for successful assembly. Solder de-wetting, and the peeling of gold caps due to prolonged HF exposure, also limits the yield and the orientation of the assembled posts.
by Hin Meng Au.
S.M.
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Bayne, Christopher D. "New directions in dimeric self-assembly." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/38398.
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Jacobs, Tia. "Self-assembly of new porous materials." Thesis, Stellenbosch : University of Stellenbosch, 2009. http://hdl.handle.net/10019.1/3970.
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Thesis (PhD (Chemistry and Polymer Science))--University of Stellenbosch, 2009.ENGLISH ABSTRACT: The primary objective of the work was to prepare and investigate new porous materials using the principles of crystal engineering. Both organic and metal-organic systems were studied and the work can best be divided into two separate sections: 1. The crystal engineering of Dianin’s Compound, a well-known organic host. 2. The design and synthesis of a series of related porous coordination compounds consisting of discrete, dinuclear metallocycles. The first section discusses the synthetic modification of Dianin’s compound in order to engineer a new clathrate host with an altered aperture size. Although this study ultimately failed to isolate the host material in its porous guest-free form, the work led to the discovery of a chiral host framework that aligns guest molecules in a polar fashion, and consequently displays non-linear optical properties. These findings are unprecedented in the long history of crystal engineering of Dianin’s compound and its analogues. This section also describes desorption studies of the new inclusion compound, as well as the known thiol analogue of Dianin’s compound. Systematic characterisation of these desorbed phases has raised interesting fundamental questions about desolvation processes in general. The second section constitutes the major portion of the work. A series of related isostructural coordination metallocycles were synthesised and their structure-property relationships were investigated using a variety of complementary techniques. These metallocyclic compounds all crystallise as solvates in their as-synthesised forms, and different results are obtained upon desolvation of the materials. In each case, desolvation occurs as a single-crystal to single-crystal transformation and three new “seemingly nonporous” porous materials were obtained. A single-crystal diffraction study under various pressures of acetylene and carbon dioxide was conducted for one of the porous metallocycles. This enabled the systematic study of the host deformation with increasing equilibrium pressure (i.e. with increasing guest occupancy). The observed differences in the sorption behaviour for acetylene and carbon dioxide are discussed and rationalised. Gravimetric gas sorption isotherms were also recorded for the three different porous materials and the diffusion of bulkier molecules through the host was also investigated structurally. Finally, a possible gas transport mechanism is postulated for this type of porous material (i.e. seemingly nonporous), and this is supported by thermodynamic and kinetic studies, as well as molecular mechanics and statistical mechanics simulations.
AFRIKAANSE OPSOMMING: Die primêre doel van die werk was om nuwe poreuse materiale te berei en deur die toepassing van beginsels van kristalmanipulasie (E. crystal engineering) te ondersoek. Beide organiese- en metaal-organiese sisteme is bestudeer en die werk kan in twee kategorieë verdeel word: 1. Die kristalmanipulasie van Dianin se verbinding, ’n bekende organiese gasheer. 2. Die ontwerp en sintese van ’n reeks verwante poreuse koördinasieverbindings wat uit diskrete, binukleêre metallosiklieseverbindings bestaan. Die eerste deel handel oor die sintetiese verandering van Dianin se verbinding om ’n nuwe klatraatgasheer met ’n veranderde spleetgrootte te vorm. Alhoewel hierdie studie nie daarin geslaag het om die gasheer in sy poreuse “gas(E. guest)-vrye” vorm te isoleer nie, het die werk ’n nuwe chirale gasheerraamwerk aan die lig gebring. Die chirale gasheerraamwerk rig gas(E. guest)molekules in eendimensionele kolomme op ’n polêre wyse en gevolglik vertoon die materiaal nie-linieêre optiese eienskappe. Hierdie resultaat is ongekend in die lang geskiedenis van kristalmanipulasie van Dianin se verbindings en sy analoë. Hierdie afdeling beskryf ook die desorpsiestudies van die nuwe gasheer, en die tiol-afgeleide van Dianin se verbinding. Die sistematiese karakterisering van hierdie fases na desorpsie het fundamentale vrae na vore gebring oor desorpsieprosesse oor die algmeen. Die tweede afdeling maak die grootste gedeelte van die werk uit. ’n Reeks verwante isostrukturele ringvormige koördinasieverbindings is gesintetiseer en hul struktuureienskap verhoudings is deur ’n verskeidenheid komplementêre tegnieke ondersoek. Hierdie metallosiklieseverbindings kristalliseer almal in gesolveerde toestand vanaf sintese en verskillende resultate word verkry wanneer die verbinding desorpsie ondergaan. In alle gevalle vind gas(E. guest)desorpsie as enkel-kristal na enkel-kristal omsettings plaas en drie nuwe ‘oënskynlik nie-poreuse’ poreuse materiale is bekom. ’n Enkelkristal diffraksiestudie onder verskeie gasdrukke is met asetileen en koolstofdioksied uitgevoer vir een van die poreuse metallosiklieseverbindings. Dit het die geleentheid geskep om die mate waartoe die gasheer as gevolg van verhoogde ewewigsdruk vervorm (en dus toename in gasheerbesetting), sistematies te bestudeer. Die waargenome verskille in sorpsie-optrede vir asetileen en koolstofdioksied word bespreek en verklaar. Gravimetriese gassorpsie isoterme is ook vir die drie poreuse materiale verkry en die diffusie van groter molekules deur die gasheer is struktureel ondersoek. Laastens word ’n moontlike gasoordragmeganisme vir hierdie tipe poreuse (i.e. oënskynlik nie-poreuse) materiale gepostuleer. Hierdie bespreking word deur termodinamiese en kinetiese studies aangevul, sowel as molekulêre-meganika en statisties-meganiese studies.
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Van, Schalkwyk Welmarie. "Self-assembly of amphiphilic discotic materials." Thesis, Stellenbosch : Stellenbosch University, 2013. http://hdl.handle.net/10019.1/79799.
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Thesis (MSc)--Stellenbosch University, 2013.ENGLISH ABSTRACT: The creation of nanometer-scale (nanoscale) materials has fascinated and inspired the scientific community for more than a quarter of a century because of the wide range of applications of these materials, e.g. applications in drug delivery, medicine, tissue engineering, memory storage, display and audio devices, semiconductors, etc. π-Conjugated dendrimers have a proposed flat packing arrangement. An alternating phenyl isoxazole dendrimer system was developed to investigate this phenomenon. The synthesis of this dendritic system was attempted by divergent and convergent approaches. Preparation of the second generation failed because some functional groups inhibited the monomers to react to the first generation. Other examples of nano materials that have attracted a vast amount of interest are the so-called discotic amphiphiles. Discotic amphiphilic molecules have the potential to self-assemble into helical architectures. Discotic systems bearing chiral polar side chains (one and three respectively) were developed. Their self-assembly was investigated in variable concentration and variable solvent composition experiments. These systems did show signs of aggregation in UV-vis and CD spectroscopy experiments. Thread-like helical structures were observed with transmission electron microscopy.
AFRIKAANSE OPSOMMING: Nanometer-skaal materiale inspireer en fassineer wetenskaplikes al vir meer as 25 jaar as gevolg van hulle wye verskeidenheid toepassings bv.: die vervoer van geneesmiddels, weefsel ontwerp, geheue stoorspasie, digitale skerms, klank toerusting, geleiers, ens. π-Gekonjugeerde dendrimere het 'n plat drie dimmensionele rangskikking. 'n Afwisselende feniel isoxazole dendrimer stelsel was ontwikkel om hierdie verskynsel te ondersoek. Die sintese van hierdie dendritiese stelsel is aangepak deur divergerende en konvergerende benaderings. Sintese van die tweede generasie het misluk omdat sommige funksionele groepe die monomere geïnhibeer het om te reageer met die eerste generasie. Ander interessante voorbeelde van nano materiale, is die sogenaamde skyfvormige amphiphiles. Skyfvormige amphiphiles het die potensiaal om spontaan te versamel in heliese strukture. Skyfvormige molekules met chirale polêre sykettings (een en drie onderskeidelik) is ontwikkel. Hulle potensiaal om spontaan te versamel is ondersoek met wisselende konsentrasie en wisselende oplosmiddel samestelling eksperimente. Hierdie stelsels het tekens van versameling gewys in UV-vis en CD-spektroskopiese eksperimente. Staaf-vormige heliese strukture is waargeneem met transmissie-elektronmikroskopie.
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Zhang, Chuchu. "Flow enabled self assembly of polymers." Thesis, Georgia Institute of Technology, 2016. http://hdl.handle.net/1853/54932.
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Self-assembly of nanoscale materials to form intriguing structures has garnered considerable attention due to their potential applications in optical, electronic, magnetic and information storage devices. Among all the efforts to pattern functional polymers and nano materials, flow-enabled self-assembly (FESA) stands out as a lithography-free evaporation-induced self-assembly technique to construct large-scale 0D, 1D and 2D periodic structures in a simple, robust and cost effective manner. In the first part of the thesis, flow-enabled self-assembly of polystyrene is chosen as the model system, and systematic experiments have been conducted to reveal intrinsic and external variables that lead to 3 possible FESA patterns (i.e., coffee ring induced spoke pattern, fingering instability induced strip pattern, and their intermediate network-like structures). In the second part of the thesis, applications of FESA in patterning electrochromic polymers and fabricating PS-PMMA strips as etching mask of Si microchannels are demonstrated. Both applications convincingly illustrate the advantages of cost effective, large yield and flexible control of flow-enabled self-assembly.
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Currie, Keith William John. "Peptide self-assembly in biomaterial design." Thesis, Queen's University Belfast, 2014. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.673801.
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The process of self-assembly of short synthetic peptides into highly complex organised hydrogel structures is currently of interest due to the fact that these can potentially form a commercially viable means of producing novel biomaterials with a diverse range of functions and applications in drug delivery and tissue engineering. This thesis aimed to design a range of bespoke short synthetic peptides and examine the effects of varying the chemistry of the N-terminus on the ability of certain dipeptide sequences to form competent hydrogelators. As the design of competent peptide hydrogelators from first principles remains a challenge in this field, an examination of the effects of N-terminus chemistry was warranted to further understand the role that the N-terminus plays in either aiding or hindering dipeptide self-assembly. Following the successful solid-phase synthesis ofa library of twenty-eight dipeptides, these compounds were tested for their ability to form hydrogels following gelation triggering using solvent based induction using DMSO and via a pH change based induction using G1ucono-delta-lactone (GdL). Eleven successful hydrogelators were identified in the DMSO induction tests and hydro gels formed using this method were assessed for secondary structure, micro-morphology and mechanical properties using FTIR, TEM and rheology respectively. The presence of aryl-oxyethyl carbonyl and ethyl carbonyl linkers in the N-terminus appeared to hinder gelation via DMSO triggering. Twenty successful hydrogelators were identified when GdL was used to cause a pH change induction. The presence of oxyethyllinker groups in the N-terminus also appeared to hinder the gelation of compounds when using pH induction. Following the analysis of the secondary structure and mechanical properties of hydro gels formed using DMSO or pH induction methods, the compounds were then tested for in vitro cytotoxicity towards the human cell lines HeLa and HaCaT. Several novel compounds were identified as candidates for further in vitro and in vivo studies.
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Wilber, Alex W. "Simulation studies of monodisperse self-assembly." Thesis, University of Oxford, 2009. http://ora.ox.ac.uk/objects/uuid:4bea99a3-5d17-4233-8065-879183ef0a32.
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The processes by which anisotropic colloidal and nanoscale particles may come together to form ordered monodisperse structures are not well understood. The canonical example of such a system is provided by the assembly of virus capsids, in which tens to thousands of particles of one or a few types assemble efficiently into ordered, highly symmetrical shells. Other examples include a wide variety of protein oligomers, and there is interest in producing analogous systems of synthetic particles. In this thesis I study the self-assembly of simple model particles, consisting of spheres decorated with attractive patches. I consider in detail the assembly of clusters of particles corresponding to the Platonic solids. For the majority of these structures assembly is found to be efficient over a wide range of parameter space. The optimal conditions represent a compromise between thermodynamic stability and kinetic accessibility. We consider two versions of the model, with and without constraints on the torsion angle of bound particles. In both cases the structures with triangular faces are found to assemble most easily. In the absence of torsional constraints dodecahedra will not assemble under any set of parameters as a result of the preferential formation of disordered aggregates. With torsional constraints included all of the Platonic solids assemble successfully and the behaviour of the model is considerably changed. In particular disordered aggregates become far less favourable. I explore possible methods of assembling larger structures, either via “hierarchical” assembly where small clusters are first assembled and then used as building blocks in another stage of assembly, or by a templating method in which an inner cluster acts as a template for a larger outer cluster. These approaches are studied using the “Virtual Move Monte Carlo” cluster move algorithm, the behaviour of which we examine in some detail.
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Lin, Tao. "Self-Assembly of Short Peptide Derivatives." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu161012283431265.
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Dalby, Thomas. "Computer simulation of micelle self-assembly." Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/19528/.
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Results are presented from a three dimensional lattice model of amphiphile-solvent and amphiphile-amphiphile-solvent systems studied using Monte Carlo simulations. This model builds upon previous models [1-11] allowing for a longer am-phiphilic head group and the inclusion of a second, different amphiphile. Detailed simulations are run using both a single amphiphile and double amphiphile model to study the self-assembly of micelles. Analysis of the results from these simulations shows that the models exhibit a critical micelle concentration together with cluster size distributions consistent with experiment and theory. Simulations of the single amphiphile model also give information on the free energy of micelle formation with the entropic and enthalpic contributions determined. It is found that the competition between the decreasing internal energy per monomer and entropy per monomer is the source of micellar behaviour. This result is then confirmed independently by calculating the partition function of an amphiphilic cluster using an extension to the Rosenbluth scheme [12-14]. Further results are also presented from simulations studying the effect of changing the head length, the hydrophilicity and the chain stiffness of the modelled am-phiphiles. Similar results for the internal energy and entropy are found concerning changes to the amphiphilic head group, however changes in amphiphilic chain stiffness highlight the importance of the structure of the micelle core.
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Antzoulatos, Nikolas. "Towards self-adaptable intelligent assembly systems." Thesis, University of Nottingham, 2017. http://eprints.nottingham.ac.uk/39583/.
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Currently, European small and medium-sized enterprises (SMEs) are experiencing increasing pressure to provide high quality goods with customised features while at the same time remain cost effective and competitive in the global market. In the future, manufacturing systems need to be able to cope with constantly changing market requirements. Consequently, there is a need to develop the research foundations for a new generation of manufacturing systems composed of intelligent autonomous entities which are able to reconfigure themselves and to adapt their performance as a result of product and environmental changes. The research described in this thesis addresses the issue by developing three distinctive elements of an adaptation framework for next-generation manufacturing systems. The first element is a capability-based data model for the representation of manufacturing resources to enable self-awareness. The model captures the resources’ life cycle and performance indicators to provide information about the resources’ condition. The second element is a multi-agent architecture for plug and produce and the reconfiguration of manufacturing systems. The resource data model is utilised by the agent society, which is able to instantiate a model to represent a physical resource in the virtual agent society. The shift to the virtual environment enables a communication infrastructure for heterogeneous resources and the application of the digital twin concept. The agent architecture applies negotiation techniques to establish a plan for system adaptation. The third element is a methodology for automated experience-based manufacturing system adaptation. The adaptation methodology is based on previous runtime experience instances to generate adaptation knowledge. The information generated is applied to the current context and part of the agent negotiation which is dynamically executed in case of a disturbance. Collectively, these three elements significantly increase the flexibility and reconfigurability of a manufacturing system reducing the time required for integration and maintenance of complex systems on demand, improving their effectiveness. The developed framework is implemented and evaluated experimentally on a physical, industrial standard demonstrator and using a virtual simulation model. The experimental results confirm a significant step towards new solutions for the deployment of self-adaptable intelligent manufacturing systems.
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Grant, A. "Self-assembly in side-chain polymers." Thesis, University of Cambridge, 1995. https://www.repository.cam.ac.uk/handle/1810/271980.
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