Thesis (Ph. D.)--University of Illinois at Urbana-Champaign, 2003. / Vita. Includes bibliographical references (leaves 113-120).

Thesis (Ph. D.)--Arizona State University, 1990. / Includes bibliographical references (leaves [137]-153).

Thesis (Ph. D.)--University of Texas at Austin, 1993. / Vita. Includes bibliographical references (leaves 145-155).

Thesis, PlanB (M.S.)--University of Wisconsin--Stout, 2006. / Includes bibliographical references.

University, Diss., 2004--Stuttgart.

Thesis (Ph.D.)--University of Nebraska-Lincoln, 2008. / Title from title screen (site viewed Feb. 17, 2009). PDF text: xii, 219 p. : ill. (some col.) ; 5 Mb. UMI publication number: AAT 3328256. Includes bibliographical references. Also available in microfilm and microfiche formats.

Self-assembly is an astonishing phenomenon at the base of organized structures’ formation from disordered systems. It occurs in nature from atomic and molecular lengths to galactic distances. Nowadays self-assembly of colloidal solutions can be used to fabricate photonic crystals and metamaterials. This paper analyses the self-assembly and its effect on the electric conductivity of a colloid made up of carbon nanotubes and magnetite microparticles controlled by electrostatic potentials and magnetic fields. Alignment of the carbon nanotubes and creation of sparks and short-circuits are observed when the electrostatic field is applied. The magnetic field induces time-dependent and memory effects in the sample’s structure and conductivity. At constant potential, the electric current through the sample is reported to increase four times during and after the application of the magnetic fields.

Made available in DSpace on 2014-06-11T19:35:40Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-12-20Bitstream added on 2014-06-13T19:05:49Z : No. of bitstreams: 1 sanches_al_dr_guara.pdf: 891253 bytes, checksum: e63f7ccd2ae9f6655be05af4f8afb22d (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / A acirrada competitividade entre as empresas de manufatura, presente no cenário atual, exige a busca por sistemas produtivos cada vez mais eficientes e que estejam inseridos num ambiente de constante aprimoramento. Visando à redução de estoques, e agilidade na produção, o conceito de produção enxuta se apresenta como um conjunto de importantes ferramentas operacionais. Desde que surgiram os conceitos associados à produção enxuta, vários estudos que tratam da utilização eficaz de Linhas de Montagem de Modelos Mistos - LMMM se concentram no sequenciamento de tais linhas. Neste trabalho, linhas de montagem múltiplas para modelos mistos, em ambiente de produção enxuta, são estruturas operacionais nas quais vários fornecedores internos abastecem várias linhas de montagem de modelos mistos simultaneamente, de modo que todas as linhas possam receber peças ou subconjuntos de todos os fornecedores. Para otimizar este sistema, a sequência de programação deve buscar o consumo constante de peças ou subconjuntos, minimizando, assim, o dimensionamento dos kanbans e estoques intermediários e, ainda, nivelar a carga de trabalho em cada posto, minimizando as paradas de linha. Baseado no clássico Problema de Monden, que determina o sequenciamento de uma única linha, este trabalho desenvolve um modelo computacional utilizando a Meta-heurística Simulated Annealing e a Simulação a Eventos Discretos para o sequenciamento do sistema de abastecimento cruzado com várias linhas. O modelo proposto busca o sequenciamento das linhas de montagem que mais aproxima o consumo real de um consumo ideal constante e atende a um padrão de eficiência predefinido para as linhas / The fierce competition between manufacturing companies, in this current scenario requires the search for production systems more efficient, and which are embedded in an environment of continuous improvement. Seeking to reduce inventories, and speed of production, the concept of lean production is presented as a range of important operational tools. Since the rise of concepts associated with lean production, several studies dealing with the effective use of assembly lines mixed models - LMMM focus on the sequencing of such lines. In this work, multiple assembly lines for mixed models, in an environment of lean production, are operating structures where several domestic suppliers supply many assembly lines mixed models simultaneously, so that all lines can get parts or subsets of all suppliers. To optimize this system, the programming sequence must seek constant consumption of parts or subassemblies, thus minimizing the scaling of kanbans, and intermediate stocks and also level the workload at each station to minimize line stoppages. Based on the classic problem Monden, which determines the sequencing of a single line, this paper develops a computational model using the Simulated Annealing metaheuristic and Discrete Event Simulation for the sequencing of the supply system with crossed several lines. The proposed model seeks the sequencing of assembly lines that most approximates the actual consumption of a consumption ideal constant and respects a predefined standard of efficiency for the lines

The synthesis, characterization and amphiphilic self-assembly of polymer brush functionalized nanoparticles (PBNPs) using a block copolymer template is described herein. To study the effect of polymer brush composition on self-assembly, four samples were created using a mixture of PS-b-PAA (polystyrene-block-polyacrylic acid) and PMMA-b-PAA (poly(methyl methacrylate)-block-polyacrylic acid) diblock copolymers to create PBNPs with a CdS quantum dot (QD) core and different ratios of PS and PMMA in the coronal brush. Static light scattering showed that despite differences in brush composition, the PBNPs formed nanoparticles of similar aggregation number and chain density but showed evidence of asymmetric structure in a common solvent for both blocks at higher PS contents. After subsequent hydrolysis of the hydrophobic PMMA to hydrophilic poly(methacrylic acid) (PMAA), these amphiphilic particles were then self-assembled in THF/H2O solution in which it was determined that increasing the hydrophobic content of the brush composition, the initial nanoparticle concentration (c0) or the added salt content (RNaCl), would cause the assembly of low curvature assemblies. Compilation of this data allowed for the construction of phase diagrams for PBNP systems based on brush composition and c0 at different salt contents. Lastly, PS-b-PAA-b-PMMA triblock copolymers with variable PMMA chain length were assembled into PBNPs around a CdS QD core using a block copolymer template approach. Light scattering showed these particles also had similar aggregation number and chain density despite the difference in PMMA chain length. After hydrolysis of PMMA to PMAA these particles were then self-assembled in THF/H2O mixtures to determine the role of PMAA block length on the produced morphological structures. The resulting assemblies suggest that chain length played a minimal role in their self-assembly / Graduate / 2018-09-15

The self-assembly peptide hydrogels used as tissue culture scaffolds have drawn great attention in recent years. They have the advantages of natural polymer hydrogels including biocompatibility, biodegradability and the advantages of synthetic materials such as controlled structural properties and mechanical properties. Furthermore, the bioactive ligands which can promote bioactivities and control cell behaviours can be easily introduced to the peptide backbone through peptide synthesis. One particular self-assembly FEFEFKFK peptide was chosen in this project.FEFEFKFK peptide used in this project has been reported to self-assemble in solution, forming hydrogels with a 3D fibrous network structure above a critical gelation concentration. In this project, the self-assembly and gelation properties of FEFEFKFK peptide were further investigated, assessing the effect of pH and ionic strength on the self-assembly and gelation behaviour. The biomimetic nanofibrous hydrogels of FEFEFKFK were also assessed for their ability to support human dermal fibroblast cells. The protocols of gel preparation were developed for both 2 dimensional (2D) and 3 dimensional (3D) cell culture. A short peptide sequence homoarginine-glycine-aspartate (hRGD) has been introduced onto the amide end of the self-assembly peptide instead of bioactive ligand arginine-glycine-aspartate (RGD), creating hydrogels with a fibrous network with functionalised groups at the fibre surface. The functionalised peptide hydrogels enhanced cell adhesion on gel surface, with cell interaction assessed using various imaging and spectroscopic techniques. A preliminary 3D cell culture study also showed potential of these peptide gels to be used for encapsulated human dermal fibroblast cell studies.