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Heim, Andreas [Verfasser]. „The role of calcineurin during exit from meiosis II in Xenopus laevis and The mitotic interplay between the Gwl/Arpp19 module and PP1 in early Xenopus embryos / Andreas Heim“. Konstanz : Bibliothek der Universität Konstanz, 2018. http://d-nb.info/1164378678/34.
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Van, Phu T. „Improving 2D Gel Proteomics With The Structured Illumination Gel Imager“. Research Showcase @ CMU, 2014. http://repository.cmu.edu/dissertations/365.
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This thesis is composed of three separate projects: 1. Proteomics is the study of complex protein mixtures found in a cell, organ, or entire organism. The vast concentration range of these samples, estimated at approximately 150,000-fold for simple unicellular eukaryotes is beyond current detection methods. We present a technology called Structured Illumination (SI) Gel Imager that employs an LCD projector to selectively illuminate fluorescently labeled proteins separated into individual protein spots on 2-dimensional electrophoresis (2DE) gels. SI Gel Imager images have a dynamic range of approximately 1,000,000-fold, making it a valuable tool for proteomic detection. 2. 2DE gels possess the ability to separate proteins with extremely high resolution of molecular-weight and isoelectric-point. However, they suffer from variable sample loss incurred during protein reduction and alkylation steps required for subsequent sequencing by mass-spectrometry, up to about 30% of the starting sample. We present a protein equilibration method utilizing agarose stacking gels to reduce experiment variability and sample loss. 3. 2DE-based proteomics is a time-consuming process, requiring up to 3 days, and suffers from low reproducibility. To provide undergraduates to the experience of conducting proteomics research, we developed the Proteomics Platoon approach, where a group of undergraduate students work in two-person teams to perform proteomic experiments using a wide variety of biological samples. The close-knit nature of the Platoon further fosters collaboration, communication and mentorship while completing complex scientific projects. The Platoon approach serves as a model for involving undergraduates in complex research projects.
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Garcez, Matias Corbett. „Gil Scott-Heron“. reponame:Repositório Institucional da UFSC, 2015. https://repositorio.ufsc.br/xmlui/handle/123456789/162579.
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Tese (doutorado) - Universidade Federal de Santa Catarina, Centro de Comunicação e Expressão, Programa de Pós-Graduação em Inglês: Estudos LinguÃsticos e Literários, Florianópolis, 2015.Made available in DSpace on 2016-05-24T17:23:20Z (GMT). No. of bitstreams: 1 338255.pdf: 2696544 bytes, checksum: 2c33da0f766af9787dd4f6a27e4bf290 (MD5) Previous issue date: 2015
Abstract : This research discusses the poetry and music of Gil Scott-Heron as toolsof resistance. In the process of analyzing his work as historical counternarratives,a dialogue was established with some considerations fromAmiri Baraka and Kodwo Eshun. To discuss the ways in which hismusic and poetry fused into a black vernacular technique-technology,and how such fusion was extremely important in the writing of manychapters of the history of African-Americans, some ideas from RayvonFouché, Larry Neal, and Baraka were used. The music of Scott-Heron isinterpreted as PhonoFiction by adapting certain thoughts from Eshun.The correspondences between black speech and black music in the workof Scott-Heron were also analyzed using concepts created by StephenHenderson. Lastly, through an analysis of his work it was concluded thathe developed a poetics of the immediate, in that, his work instigatesimmediate action from African-Americans in their collective strugglefor equality and freedom.
Esta pesquisa analisa a música e poesia de Gil Scott-Heron como ferramentas de resistência. Para discutir sua obra enquanto uma contranarrativa histórica estabeleceu-se um diálogo com Amiri Baraka e Kodwo Eshun. Para analisar as maneiras que a música e poesia de Scott- Heron se fundiram em uma técnica-tecnologia vernácula negra, e como tal fundição foi extremamente importante na escrita de diversos capÃtulos da história Afro-Americana, seguiram-se ideias de Rayvon Fouché, Larry Neal e Amiri Baraka. A música de Scott-Heron também é analisada enquanto FonoFicção, adaptando-se pensamentos de Eshun. Também se discutiu as correspondências entre a fala negra e a música negra, na obra de Scott-Heron, seguindo ideias de Stephen Henderson. Por fim, através da análise da obra de Scott-Heron concluiu-se que ele desenvolveu uma poética do imediato, no sentido de que sua obra instiga uma ação imediata de afro-americanos para uma luta coletiva por igualdade e liberdade.
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Karsson, Oscar. „GNU GPL i komparation - Om GPL-licensen i Sverige och Kalifornien“. Thesis, Umeå universitet, Juridiska institutionen, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:umu:diva-159255.
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VIDAL, OLGA. „Cristallogenese d'un lysozyme en gel d'agarose et en gel de sicile“. Paris 6, 1997. http://www.theses.fr/1997PA066577.
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Ce travail concerne l'etude de la nucleation-croissance d'une macromolecule biologique : le lysozyme de blanc d'oeuf de poule. Nous avons analyse les processus de cristallogenese dans le gel d'agarose et le gel de silice. Nous avons montre, par diffusion de neutrons aux petits angles (principale methode d'investigation) que l'effet promoteur de nucleation du gel d'agarose ne pouvait pas s'expliquer par une sursaturation locale plus grande (hypothese de depart) mais par l'existence d'agregats de grandes tailles (>500a) plus nombreux en gel du fait de l'absence de processus destructifs comme la sedimentation et les mouvements de convection. L'effet inhibiteur de nucleation du gel de silice s'explique, non pas seulement par un effet de confinement de la solution (hypothese de depart), mais par l'adsorption des molecules de proteine a la surface du gel par interaction de nature liaison hydrogene et electrostatiques, diminuant ainsi la sursaturation. Il semble que l'hypothese d'une nucleation a partir des molecules restant en solution est plus probable que celle d'une nucleation a partir des molecules adsorbees. La caracterisation des cristaux par rx nous montre que les cristaux obtenus en gel de silice de meilleure qualite que ceux obtenus en gel d'agarose, ces derniers etant en moyenne de meilleure qualite que ceux obtenus en solution libre. Ceci suggere que l'adsorption sur le gel de silice s'accompagne d'un effet de selectivite tel que les molecules denaturees soient eliminees du milieu de nucleation. L'interferometrie holographique confirme que le gel d'agarose est neutre vis-a-vis de la proteine et que le transfert de matiere se fait bien par diffusion, alors que la proteine interagit de facon reversible avec le gel de silice.
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Kokkinakis, E. N. „Interaction between gel strength and yeast cells immobilized in calcium alginate gel“. Thesis, Swansea University, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637820.
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The objective of the project is to improve the durability of calcium alginate gel, as an immobilizing matrix for yeast in aerobic culture, by increasing the alginate content of the gel in the range 4.5, 6.0, and 8.0 wt%, so that the immobilized yeast bioparticle can be used for at least 500 hours continuous culture, and to investigate the interaction between the gel matrix and the immobilized cells. The yeast, S.cerevisiae NCYC 1026, has been aseptically immobilized in thin calcium alginate gel discs (2.0 mm by 7.0 mm) of the required alginate content, and aerobically cultured at + 25°C and pH 4.5 in a chemically defined liquid culture medium. The immobilized yeast gel discs have been continuously cultured in an air lift bioreactor for at least 500 hours. The kinetic state of the immobilized cells and the immobilized biomass hold-up were measured independently, such that these data were available for the analysis of the continuous bioreactor, using mathematical models of the bioreaction system. The calcium alginate gel was found to reduce yeast growth and yield slightly, but to have a significant effect on glucose uptake by inducing active transport in the yeast. Otherwise the gel had no adverse action on the yeast, indeed the gel matrix tended to maintain yeast viability, when the immobilized cell gel discs were stored for up to 3 months with no glucose supply. During continuous culture the key operational parameters were found to be effective diffusivity of glucose in the gel matrix solid phase and immobilized cell biomass hold-up, possibly linked to the inconstant cell mass leakage rate from the gel. The 6.0 wt% alginate content gel was found to be the optimum gel for immobilized cell function and durability of the gel. Nevertheless the effective diffusivity even in this gel was only 1.0% of that in water, much lower than previously reported.
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Lee, Woojin. „Polymer gel based actuator : dynamic model of gel for real time control“. Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/10939.
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Queiroz, Neide. „Aplicações sinteticas de enzimas imobiliadas em organo-gel e gel de agar“. reponame:Repositório Institucional da UFSC, 1997. http://repositorio.ufsc.br/xmlui/handle/123456789/77029.
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As microemulsões água-em-óleo (água + óleo + surfactante) podem ser utilizadas para formar géis elásticos e termoreversíveis pela adição de gelatina. Este sistema é chamado de organo-gel ou MBG (do inglês, "microemulsion-based gels"). As mudanças que ocorrem no organo-gel, quanto a sua estabilidade, foram observadas fixando a concentração do surfactante AOT (di-2-etilhexil sulfosuccinato de sódio) em 0,15 mol/L e variando a quantidade de água, n-heptano e gelatina. A avaliação visual à temperatura ambiente de cada organo-gel possibilitou distinguir três regiões diferentes através do diagrama de fases, que foi obtido pelo gráfico da concentração de gelatina versus W0. As enzimas papaína e palatase M foram imobilizadas em organo-gel de n-heptano. Verificou-se que a papaína destrói o sistema e a palatase M não o altera. Usando palatase M imobilizada em organo-gel, uma série de ésteres alifáticos foi sintetizada sob condições suaves e com bons rendimentos. Parâmetros tais como tamanho da cadeia e ramificações próximas ao centro nucleofílico do álcool foram analisados e associados com a atividade catalítica desta enzima no sistema de MBG. O organo-gel com palatase M foi reutilizado, mostrando que depois de dez conversões a enzima mantém sua atividade catalítica e o sistema permanece inalterado. O gel de ágar também foi usado para imobilizar papaína e palatase M, sendo que o suporte permaneceu estável. Estas enzimas foram usadas em reações de esterificação e aminólise de éster. Com a palatase M imobili7nda em gel de ágar estudou-se o efeito do pH e da temperatura na síntese do laurato de n-pentila. O rendimento do éster não mostrou ser dependente do pH, mas dependente da temperatura.
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Yang, Quanzu. „Composite sol-gel ceramics“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1999. http://www.collectionscanada.ca/obj/s4/f2/dsk1/tape8/PQDD_0019/NQ46453.pdf.
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Odero, Christine A. (Christine Adhiambo). „Polymer gel spinning machine“. Thesis, Massachusetts Institute of Technology, 1994. http://hdl.handle.net/1721.1/34092.
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Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1994.Includes bibliographical references (leaves 117-118).
by Christine A. Odero.
M.S.
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Moreira, Marcos Flávio Pinto. „Secagem de gel ágar“. Universidade Federal de São Carlos, 2000. https://repositorio.ufscar.br/handle/ufscar/4006.
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Previous issue date: 2000-02-29Financiadora de Estudos e Projetos
Agar-agar is a hydrofilic colloid extracted from seaweed, mainly from algae Gelidium. It s used as culture medium in microbiology and as emulsificant, stabilizer and gelling in foods. Drying is an important operation in the extractive process to obtain Agar-agar, because it defines the form, color and final moisture content of product. In order to study the drying of agar gel, equilibrium and drying experiments are needed. The equilibrium of agar-water-air was investigated using the static gravimetric method and drying experiments were performed in a forced convection dryer. To determine equilibrium moisture content values, the static method was used with saturated saline solutions where operational conditions of temperature and relative humidity ranged from 25.0°C to 50.0°C and 11.0% to 84.0%, respectively. The determination of moisture content was based on Lees method. The drying experiments were performed with temperatures from 30.0°C to 50.0°C and superficial air velocities from 1.0 to 4.0 m/s. Based on the experimental procedure above, the equilibrium of agar-water-air could be reasonable described by the G.A.B. (Guggenheim-Anderson-de Boer) model. It was verified, using Lewis equation, that temperature and velocity of air influence the drying operation. Finally, at a constant drying rate, the drying of agar gel and water are very similar. The constant drying rate of agar gel has been represented by a relationship for evaporation of water. The decreasing drying rate of agar gel was represented by the characteristic curve. All results obtained in this work serve as contribution to the process to obtain the agar, which utilizes the drying.
O ágar é um colóide hidrofílico usado nos setores de microbiologia e alimentos, entre outros. Uma das operações mais importantes no processo de obtenção do ágar é a secagem. Com o objetivo de estudar a secagem do gel ágar faz-se necessária a realização das determinações das isotermas de equilíbrio e experimentos de secagem. O equilíbrio ágar-água-ar foi estudado via método gravimétrico estático com soluções salinas saturadas, nas temperaturas de 25 a 50°C e umidades relativas do ar de 11 a 84% e os experimentos de secagem foram realizados em um secador de convecção forçada nas temperaturas de 35 a 50°C e velocidades superficiais do ar de 1,0 a 4,0 m/s. A determinação da umidade baseou-se no método de Lees. O modelo G.A.B. (Guggenheim-Anderson-de Boer) representou bem o equilíbrio entre os modelos analisados. Constatou-se, através da equação de Lewis, que a temperatura e a velocidade do ar influenciam a cinética de secagem do gel. Constatou-se ainda que a secagem do gel no período de taxa constante de secagem é similar à da água. Este período de secagem foi representado por uma relação para evaporação da água e o período de taxa decrescente por uma curva característica generalizada. Todos os resultados obtidos sobre a transferência de massa na secagem do gel ágar servem de contribuição para a continuidade dos estudos sobre o processo de obtenção do ágar, servindo também de base para a busca de diferentes tipos de secadores convectivos e de condições ótimas de operação ligadas à relação custo de produção x produção .
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Marques, João Miguel Resende. „"GWB" simulation software development“. Master's thesis, Universidade de Aveiro, 2009. http://hdl.handle.net/10773/1768.
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Mestrado em Engenharia e Gestão IndustrialNas últimas décadas, a evolução da indústria alcançou uma extrema importância na nossa vida pessoal e também no comportamento empresarial. O conjunto de ferramentas existentes nos computadores representam um papel fundamental na comunicação, nas estratégias, nas decisões, nos sistemas de análise de processos das nossas empresas, entre outras. Os software são normalmente concebidos para permitir aos os seres humanos realizar tarefas para as quais o cérebro humano não é capaz, tais como: manipulação de grandes quantidades de informação, realização de cálculos complexos, e controlar simultâneamente muitos processos. Este projecto final foi desenvolvido exactamente sobre a disciplina de software. O presente documento mostra como uma empresa multinacional desenvolve internamente um novo software modular. Algumas técnicas serão investigadas e aplicadas a um problema real existente na empresa Robert Bosch-Bélgica, pertencente ao sector automóvel e principal responsável mundial pela produção de limpa pará-vidros. Aqui se encontrará uma sugestão para uma metodologia do ciclo de vida de um software e será explicado passo a passo todos os aspectos deste processo, desde a criação até ao desenvolvimento desta nova ferramenta de cálculo de apoio à decisão para o design. Esta metodologia foi aplicada à empresa permitindo assim a criação de um manual para o software de simulação chamado “GWB”. Mais precisamente, este projecto descreve a fase de testes, definido como a validação. Esta fase inclui um planeamento e execução de testes do software. Estes resultados foram analisados e comparados com as medições reais. Com base em conhecimentos anteriores, foi conseguido melhorar a precisão do software quer em parâmetros de produção quer em parâmetros de comportamento real dos limpa pará-brisas. Com a criação do manual e do melhoramento do software foram alcançados os dois objectivos principais envolvidos neste estágio. Este trabalho contribuiu significativamente para o desenvolvimento do software de simulação da Robert Bosch, no entanto, é sugerido um conjunto de acções futuras. Estas têm como objectivo ajudar no desenvolvimento do “GWB” para uma implementação adequada no processo de produção de limpa pará-brisas. ABSTRACT: In the last decades the evolution of software industry has reached an extreme importance in our personal daily life and also in the companies behavior. The existing sets of tools represent a vital role in our company’s communications, strategies, decisions supports, systems and process analysis, among others. Software is typically designed to enable humans to perform tasks which the human brain is not well capable, such as: handling large amounts of information, performing complex calculations, and controlling many simultaneous processes. This final project was developed based under the subject software. The present document shows how a multinational enterprise develops internally a new modulate software. Some techniques will be investigated and applied to a real life problem existing in the successful Robert Bosch-Belgium company at the automobile industry world responsible for the production of wiper blades. Here you will find a suggestion of a software life cycle methodology and an explanation step by step of all the aspects of this process from the creation to the development of a new calculation tool for design decision support. This methodology was applied to the company thus enabling to create a handbook for the simulation software called “GWB”. More precisely this project describes the testing phase, defined as validation. This phase contains the planning and execution of software tests. These results were analyzed and compared with real measurements. Based on previous knowledge, was able to improve the accuracy of the software either in production parameters or on parameters of actual behavior. With the creation of the manual and the software improvement two main objectives involved in this internship were accomplished. This work contributed significantly to the development of the Robert Bosch simulation software. However, it is suggested several future actions. To assist in the development of the “GWB” tool for a proper implementation in the wiper blade production process.
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Westerberg, Julia. „Gal Pals in Print“. Thesis, Konstfack, Textil, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:konstfack:diva-5955.
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Råsmark, Per Johan. „On the Structure and Dynamics of Polyelectrolyte Gel Systems and Gel-surfactant Complexes“. Doctoral thesis, Uppsala universitet, Fysikalisk-kemiska institutionen, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-4652.
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This thesis describes the results of experimental work on polyelectrolyte gels and their interaction with oppositely charged surfactants, and presents two new algorithms applicable to the simulation of colloid and polymer systems. The model systems investigated were crosslinked poly(acrylate) (PA) and poly(styrene sulphonate) (PSS), and the surfactant was dodecyl trimethylammonium bromide (DoTAB). Pure gel materials were studied using dynamic light scattering. It was shown that the diffusion coefficient (D) increases with increasing degree of swelling and the concentration dependence is larger than predicted by scaling arguments. For gels at swelling equilibrium D increases with increasing degree of crosslinking. In subsequent studies on gel particles in DoTAB solution, Raman spectra were recorded at different positions in the gel. For both types of gels two distinct regions could be observed. For PA the surfactant is localised in the outer phase without any surfactant in the core, while for PSS the surfactant was distributed such that it had the same concentration relative to the polymer throughout the gel. In a second experiment, the kinetics for the deswelling of microscopic PSS particles in DoTAB solution was studied. It was found that the final volume varied linearly with the DoTAB concentration, and the rate of volume decrease could be fitted to a single exponential indicating stagnant layer diffusion to be the rate limiting process for the deswelling of the PSS particles. In the second part, I first describe an algorithm showing an efficient way to detect percolation in simulations, with periodic boundary conditions, using recursion. Spherical boundary conditions is an alternative to periodic boundary conditions for systems with long-range interactions. In the last part, the possibility to use the surface of a hypersphere in four dimensions for simulations of polymer systems is investigated, and algorithms for Monte Carlo and Brownian dynamics simulations are described.
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Gao, Xiaonan. „Sol-Gel Assembly of Metal Nanostructures into Metallic Gel Frameworks and Their Applications“. VCU Scholars Compass, 2016. http://scholarscompass.vcu.edu/etd/4319.
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The advent of nanoscience and nanotechnology has sparked many research forefronts in the creation of materials with control over size, shape, composition, and surface properties.1,2 However, for most of the applications, nanoscale materials need to be assembled into functional nanostructures that exhibit useful and controllable physical properties. Therefore, numerous efforts on the assembly of nanoparticles (NPs) using organic ligands, polymers and polyelectrolytes have been reported.3,4 However, the interactions between NPs are mediated by intervening ligands, which are detrimental to charge transport and limit the thermal stability. Hence, developing a new method to produce solid state nanostructures with direct NP linkage has become a significant challenge. To avoid the bridging ligands and improve the conductivity of NP based solid state structures, a novel strategy has been developed in which colloidal NPs undergo condensation to wet “jello-like” hydrogel with direct interfacial linkage. Then hydrogels can be dried supercritically to produce aerogels.5 Resultant nanostructures exhibit low densities, large open interconnected pores, and high internal surface areas and are containing entirely of colloidal metal NPs.6 Since noble metal NPs have been widely used in applications such as catalysts, sensors, and novel electrochemical device components, we herein expanded the sol-gel method to noble metal NPs to produce a new class of metal aerogels.
In the dissertation, the synthesis of hollow Ag hollow NPs, Au/Ag alloy NPs, and Au/Pt/Ag alloy hollow NPs with tunable sizes and physical properties, and their oxidative-assembly into high-surface-area, mesoporous, self-supported gel framework has been achieved. The gelation kinetics have been controlled by tuning the oxidant/thiolate molar ratio that governs the rate of NP condensation, which in turn determines the morphology, optical transparency, surface area, and porosity of the gel frameworks. These low-density mesoporous nano-architectures displaying optical transparency or opacity, enormously surface area, and interconnected meso-to-macro pore structure are promising candidates for catalytic, electrocatalytic, and SERS-based sensing applications. The SERS activity of Au/Ag alloy aerogels has been studied and significant signal enhancement was achieved. The performance of the Au/Pt/Ag aerogel towards methanol oxidation reaction has been studied via cyclic voltammetry and significant electro-catalytic activity was observed.
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Rigolin, Pascoal Henrique da Costa. „Avaliação global dos modos energéticos de transporte do gás natural inclusive como energia secundária“. Universidade de São Paulo, 2007. http://www.teses.usp.br/teses/disponiveis/86/86131/tde-05092007-161143/.
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O objetivo do trabalho é fazer a avaliação global de alguns dos modos energéticos de transporte do gás natural (gasodutos, GNL e GNC), inclusive como energia secundária (eletricidade e GTL). Para a escolha do melhor modo de transporte, além dos custos de cada projeto, serão considerados outros três fatores, que são: impactos ambientais, impactos sociais e riscos políticos. Para isto foi escolhida uma ferramenta de análise conhecida como Avaliação de Custos Completos (ACC), sendo que esta considera os quatro fatores citados anteriormente como de mesma importância na avaliação para um planejamento que vise a sustentabilidade. Para melhor visualização e entendimento do trabalho, foi feito um estudo de caso para o transporte de energia (gás natural e/ou eletricidade) para atender mercados consumidores na região de fronteira entre o Brasil e a Bolívia. Fundamentalmente o estudo do transporte foi feito em solo boliviano, correspondente entre os campos produtores de gás, localizados em Margarita, até a região de fronteira próxima a Corumbá no Mato Grosso do Sul (MS), e também próxima a uma região com grandes jazidas de minério de ferro conhecida como El Mutún. Metodologicamente dentro das quatro dimensões consideradas, foram usados alguns subcritérios mais relevantes para esta análise. Para todos os sub-critérios foram atribuídas notas específicas, de acordo com a região e com o tipo de transporte de energia, e após isto os dados foram passados para um software de tomada de decisão chamado Decision Lens, obtendo assim um rank das melhores opções transporte para a região. Como resultado, o mais coerente para atender a região, são gasodutos de transporte para as demandas elétricas e de gás natural (consumo do MS mais Mutún) e trens carregados com derivados líquidos do gás natural (GTL) para atender a demanda de diesel do MS.The objective of this work is to make a global evaluation of some energy ways of transport of natural gas (gas-pipelines, LNG and CNG), as well as secondary energy (electricity and GTL). For the selection of a better way of transport, beyond the costs of each project, others three factors were considered: environmental impacts, social impacts and political risks. To perform this, a tool of analysis known as Evaluation of Complete Costs (ACC in portuguese) was chosen. This tool considers the four factors above mentioned as having the same importance in the evaluation process for planning that aims towards sustainability. For better visualization and understanding of the work, a case study for energy transport was made (natural gas and/or electricity) to supply the consumer markets in the region bordering Brazil and Bolivia. Basically the study of the transport was made in Bolivian territory; at the producing gas fields located in Margarita as far as the region bordering Corumbá in the Mato Grosso do Sul area, and also next to a region with great known iron ore deposits known as El Mutún. Methodologically, within the four dimensions above, some more relevant sub-criteria for the analysis were used. For all the sub-criteria considered specific ranks were taken, in accordance with the region and type of transported energy, and after this the data was fed to a software called Decision Lens, thus getting a rank of the best options to carry gas to the region. The results, most coherent way to supply gas to the region, happens to be gas-pipelines of transport for the electric and natural gas demands (consumption in MS plus Mutún) and trains with liquid derivatives of natural gas (GTL) to supply care of the demand of diesel of MS.
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Jarahnejad, Mariam. „New Low GWP Synthetic Refrigerants“. Thesis, KTH, Tillämpad termodynamik och kylteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-96118.
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Zheng, Lei. „Cobaltferrite-bariumtitanate sol-gel biferroics“. College Park, Md. : University of Maryland, 2006. http://hdl.handle.net/1903/3648.
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Thesis (M.S.) -- University of Maryland, College Park, 2006.Thesis research directed by: Dept. of Material Science and Engineering. Title from t.p. of PDF. Includes bibliographical references. Published by UMI Dissertation Services, Ann Arbor, Mich. Also available in paper.
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Carrillo, Agirre Amaia. „Time Tracking System with GWT“. Thesis, Linnaeus University, School of Computer Science, Physics and Mathematics, 2010. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-7105.
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Applied Research in System Analysis (ARiSA) AB, is a company whose main objective is to market the VizzAnalyzer™ software quality tool and related services, experiences, and research results.
In the beginning, recording the time spent on different activities and projects for project control, cost calculation, and customer billing manually and individually was sufficient and effective. With the number of projects and people involved at a time increasing the existing mechanisms were not sufficient anymore and needed to be replaced to support an efficient recording of time and report generation.
To solve this situation, a prototype of a web-based time tracking system was implemented. The task for this thesis was to build on the existing prototype implementation, to improve and complete it. In detail, to extend the functionalities of the web application adding user, project and activity management, and report creation.
The solution supports an efficient time tracking for employees and it makes the report generation easier.
This thesis describes the requirements for the project and the resulting implementation.
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Lee, William K. „Solid-gel interactions in geopolymers“. Connect to thesis, 2002. http://repository.unimelb.edu.au/10187/1071.
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This is partly because the requirements for such an ultimate material change with people’s perception about its properties as well as its environmental impact. Thus, the once-believed ultimate Portland cement binder is now becoming unacceptable for a number of reasons including poor durability as well as severe environmental impact during production. Thus, an improved mineral binder is required by modern society to serve the same purposes as the existing Portland cement binder, as well as to reduce the current environmental impact caused by Portland cement production.Geopolymerisation is such a ‘green’ technology capable of turning both natural ‘virginal’ aluminosilicates and industrial aluminosilicate wastes, such as fly ash and blast furnace slag, into mechanically strong and chemically durable construction materials. However, the source materials for geopolymer synthesis are less reactive than Portland cement clinkers and the chemical compositions of these source materials can vary significantly. Consequently, product quality control is a major engineering challenge for the commercialisation of geopolymers.
This thesis is therefore devoted to the mechanistic understanding of the interfacial chemical interactions between a number of natural and industrial aluminosilicates and the various activating solutions, which govern the reactivity of the aluminosilicate source materials. The effects of activating solution alkalinity, soluble silicate dosage and anionic contamination on the reactivity of the aluminosilicate source materials to produce geopolymeric binders, as well as their bonding properties to natural siliceous aggregates for concrete making, are examined. In particular, a new set of novel ‘realistic’ reaction models has been developed for such purposes. These reaction models have been further utilised to develop a novel analytical procedure, which is capable of studying geopolymerisation on ‘real’ geopolymers in situ and in real time. This novel procedure is invaluable for the total understanding of geopolymerisation, which is in turn vital for effective geopolymer mix designs.
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Fatah, Kamaran Tahir. „Studies on fibrin gel structure /“. Stockholm, 1998. http://diss.kib.ki.se/search/diss.se.cfm?19980608fata.
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Kappes, Daniel. „Nebenbestimmungen im Fusionskontrollrecht des GWB /“. Berlin : TENEA Verl. für Medien, 2002. http://www.gbv.de/dms/ilmenau/toc/364681349.PDF.
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Hawkins, K. M. „Rheometry for gel point detection“. Thesis, Swansea University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.637247.
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Various types of rheometry for gelling systems, in particular for detection of a Gel Point, have been investigated. Such rheometry will require rapid measurements and invoke small strains in order to Theologically characterise strain-sensitive materials, such as gelling systems. The Gel Point is of wide scientific and engineering interest. Prior to the Gel Point the material may be readily processed whilst in a Post gel state the material hinders flow processes but provides a measure of long term mechanical stability. It is often vital that all flow processes are carried out prior the Gel Point. The Gel Point represents the case where the connectivity spans the entire sample. In terms of the Winter-Chambon gel Equation, which represents a rheological 'equation of state' of the critical gel, and is characterised by a power-law dependence of the stress relaxation modulus. This power law yields a stress relaxation exponent, a, which has been shown to be related to a fractal dimension, df The fractal dimension is extremely important in terms of the structural characteristics of the critical gel. The Gel Point, as represented by the Winter-Chambon Gel Equation infers a frequency independent loss tangent. This characteristic frequency independent loss tangent provides us with a convenient method of detecting the Gel Point, which may be exploited by various rheometrical means. This thesis examines various rheometrical techniques, including low frequency dynamic testing and high frequency shear wave propagation, and their applicability to detect the Gel Point. In particular, much of the work herein has focussed on determining the linear viscoelastic ranges of transient systems by utilising a Fourier analysis procedure, whereby the response of an imposed strain is sampled. A criterion has been developed which unambiguously determines the onset of a nonlinear rheological response. Linear viscoelastic measurements using various rheometers have been conducted on a gelling system, to determine its Gel Point and associated gel properties. The process industry demands a highly robust and sensitive rheometer suitable for online detection of the Gel Point. A new type of sensor which utilises the Giant Magneto Impedance effect is extremely robust and sensitive. This sensor is the Amorphous Wire Transducer and initial tests have been conducted with a view to employing such sensors on high frequency rheometers, such as the Pulse Resonance Rheometer and Virtual Gap Rheometer.
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Gardener, Martin. „Studies in sol-gel chemistry“. Thesis, Nottingham Trent University, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.341276.
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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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Mitwalli, Ahmed Hamdi. „Polymer gel actuators and sensors“. Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9969.
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Thesis (Sc. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1998.Includes bibliographical references (p. [351]-361).
by Ahmed Hamdi Mitwalli.
Sc.D.
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Alcazar, Jorba Daniel. „A conjugated polymer plastic gel“. Thesis, Massachusetts Institute of Technology, 2008. http://hdl.handle.net/1721.1/45359.
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Includes bibliographical references (p. 107-119).Thesis (M. Eng.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, 2008.
We present a gel route to process highly oriented conjugated polymer films and fibers. The incorporation of hexafluoroisopropanol, a strong and stable dipolar group, to the polythiophene backbone enhances the solubility and especially, the hydrogen bond forming capabilities of the polymer. This functionalization enables the polymer to build up an isotropic self-supporting network structure based on a combination of polymer-polymer chain interactions and interchain hydrogenbondings. These thermally reversible physical crosslinks incorporate plasticity in the conjugated polymer gel. The gel network can be melted and then transformed via mechanical deformation to form an anisotropic gel with the chains highly aligned along the tensile direction. The oriented gel morphology comprises a distribution of crystalline clusters in an overall swollen network. In these ordered regions, conjugated backbones are [pi]-stacked with respect to each other neighbors. The mechanically induced structural rearrangement from an isotropic to an anisotropic conjugated polymer gel occurs when transitioning from the molten state to the gel state. This study highlights the versatility of incorporating plasticity in the design of conjugated polymer materials via a gel processing technology and its potential for applications.
by Daniel Alcazar Jorba.
M.Eng.
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Heusghem, Nathalie. „"Sternbergia lutea" L. Ker-Gawl“. Paris 5, 1995. http://www.theses.fr/1995PA05P181.
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Penel, Vincent. „L'électrophorèse en gel de polyacrylamide“. Paris 5, 1988. http://www.theses.fr/1988PA05P254.
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Shetty, Pramod. „Study on Supramolecular Gel Lubricants“. Thesis, Luleå tekniska universitet, Institutionen för teknikvetenskap och matematik, 2019. http://urn.kb.se/resolve?urn=urn:nbn:se:ltu:diva-76007.
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Most of the rolling element bearings are lubricated with Grease lubricant. Generally, the grease is expected to serve for life. The major causes of the bearing failure are due to the failure of the lubrication. The grease will experience creeping, oil permeation, oil separation etc. The separated oil will be lost permanently from the bearing. The widely used grease for general application is the lithium grease. The thickener of the grease consists covalent bond. When the grease is sheared, the breakage of the covalent bond will be permanent, resulting in the permanent loss of the rheological properties. The gels have unique properties such as thermal reversibility, viscoelasticity and thixotropy. They become mobile under shear stress and solidify again when the shear stress is removed. This property can be harnessed to avoid the base oil creeping, oil permeation, leakage in gears and bearings. Due to the presence of the polar group in the gels, they form a good tribo film and prevent the wear. Under the shear stress, weak supramolecular interactions will be distorted, and this leads to the release of the oil and they re-form the structure after a certain period of rest. When the gel is in the solid-state, it will avoid creeping and evaporation. Many classes of gels are either derived from natural sources or from environmentally friendly materials. Thus, the lubricant formed out of gel would effectively solve both environmental as well as lubrication problems. In this work, supramolecular gel lubricants were prepared out of fully green, cellulose derivatives and starch hydrolysates. The non-ionic hydroxyethyl cellulose (HEC) and anionic sodium carboxymethyl cellulose (NaCMC) were chosen to understand the effect of ionic and non-ionic gelators on the rheological and the tribological parameters. Traditionally fat was used as a lubricant, now, in food industry various fat replacers are being used. To study whether the fat replacers can act as a thickener, Dextrin and maltodextrins were chosen. Dextrin and maltodextrin with the different DE values were selected to understand the influence of molecular weight on gelation and tribological performance. Inspired by the recent developments and advantages of aqueous lubrication, mixer of water and poly(ethylene glycol) 200 (PEG 200) is chosen as the base fluid. It was found that a very small amount of gelator can increase the viscosity of the PEG/water to several orders. The thermal stability of the gels was studied using thermogravimetric analysis (TGA) and found that gels can increase the thermal stability of the base fluid. FTIR results showed the formation of a non-covalent bond between the PEG molecules and water. It is shown that anionic gelator will result in producing low friction and wear in comparison to non-ionic gelator. The possible tribo-film formation due to the negative charge in the NaCMC molecules is attributed to these results. The very low friction and low wear was exhibited by the dextrin and maltodextrin gels. It is proposed that this could be due to the microspherical particles of gels which can act as nano bearings. It was found that choosing the optimum concentration of the gelator is important to reduce friction and wear. The higher gelator concentration will form the hard gel, which cannot flow and replenish the sliding contact, resulting in the starved lubrication. This will cause high wear and friction. These gel lubricants can be used in food, pharmaceutical and biomedical industries.
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Borislav, Simendić. „Niskotemperaturno procesiranje sol-gel mulita“. Phd thesis, Univerzitet u Novom Sadu, Tehnološki fakultet Novi Sad, 2003. https://www.cris.uns.ac.rs/record.jsf?recordId=71471&source=NDLTD&language=en.
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Apstrakt je obrađen tehnologijama za optičko prepoznavanje teksta (OCR).Mehanizam nastanka mulita zavisi od načina doziranja polaznih oblika reaktanata kao što su alumina i silika. Dobijanje mulita sol-gel postupkom je u velikoj meri poboljšano u odnosu na klasično procesiranje zbog mogućnosti homogenog mešanja AI2O3 i SiO2 komponenti i kontrole dodataka. Sol-gel metod omogućuje pripremu vrlo homogenih i reaktivnih gelova koji mogu da sinteruju na nižim temperaturama pri čemu se može postići vrlo fina mikrostruktura. U ovom radu koji se odnosio na procesiranje mulita sol-gel postupkom, hipoteza je bila da se na samom početku procesiranja aluminijumovi joni iz alkoholnog rastvora Al-soli uključuju u polimernu gel strukturu koju formira silika. Svrha ovog rada, je proučavanje uticaja procesnih promenjivih, dodatka fluornog jona i “seedinga” na temperaturu nastanka sol-gel mulita pri čemu se očekuje što je moguće niža tempertura nastanka mulita (niža od 9800C). Polimerni sol je dobijen u prvom slučaju mešanjem TEOS-a i aluminijum nitrata nanohidrata koji je prethodno rastvoren u etil alkoholu. U drugom slučaju, u polimerni sol je dodavan fluorni jon u koncentraciji 2 do 5 % mas. u odnosu na očekivani prinos mulita i u trećem slučaju je dodavana različita količina mulitnih klica (2-4 % mas.). Eksperimantalno je potvrđeno da procesne promenljive; pH, temperatura geliranja i R odnos imaju, veliki uticaj na brzinu geliranja i na nastanak mulita. U slučaju dodavanja fluornog jona, potvrdena je hipoteza da fluorni jona na različite načine utiče na mehanizam nastanka mulita, pri čemu u prvom slučaju prisustvo fluornog jona obezbeduje mesta u oblastima razdvajanja granica faza nakon geliranja koja utiču na proces nukleacije. Ova mesta slično procesu kristalizacije stakla, omogućuju lakšu nukleaciju mulita prilikom njegove transformacije iz gela. Mesta na granici razdvanja faza postaju mesta na kojima se uspostavlja proces heterogene nukleacije što je jedan od mogućih načina za snižavanje temperature nastanka mulita. Pored ovoga, dodavanje fluornog jona je doprinelo promeni mulitnih gel struktura, pri čemu je promena brzine hidrolize silike imala za posledicu promenu sadržaja vezane vode u toku geliranja što se takođe značajno odražavalo na temperaturu nastanka mulita. Eksperimentalni rezultati termički obradenih gelova su pokazali, da dodavanje lluornog jona u polimerni mulitni sol stvara uslove za snižavanje temperature obrazovanja mulita sve do 8900C. U ovom radu je takođe pokazano da mulitne čestice, kao nukleanti pri “seeding" procesiranju, doprinose nastanku mulitnog gela koji nakon termičke obrade na 10000C pokazuje veoma finu mikrostrukturu.Abstract was processed by technology for Optical character recognition (OCR).The mechanism of mullite formation depends upon the method of combining the alumina and silica containing reactants. Mullite can be obtained through the sol-gel process and can be greatly improved by the control of some reaction conditions particulaiiy by homogeneous mixing of Al2O3 and SiO2, and controlling of the additions. Sol-gel method allow preparation of very homogenous and reactive gels which can be sintering at low temperature and consequently submicronic microstructure can be reached. In this study of the mullite formation by sol-gel method, the hypothesis was that aluminium ions from alcoholic solulion of its salts incorporate to polymeric silica gel structure. The aim of this work was the investigation of the effect processing variables, fluorine addition and “seeding”on the temperature of sol-gel mullite formation and to obtain as lower temperature of mullite formation as possible (smaller than 980°C). Polymeric sols, were prepared by the mixing of TEOS and aluminum nitrate nanohydrate dissolved in absolute ethyl alcohol and by adding fluorine ions in the second case from 2 wt.% to 5 wt.% and by different content of mullite seeded (2- 4 wt. %). Experimentally is determined that the processing variables as pH, gelling temperature and R ratio have high influence on the gelling rate and mullite formation. The hypothesis in the case of fluorine addition was that addition of fluorine ions could have different effects on the mechanism of mullite formation; the first it makes the sites at boundary of phase separation regions after gelling which influence at the process of the nucleation. These sites will act as a place for easy mullite nucleation, similar to process of the glass crystallization. The boundaries of the phase separation are the sites for heterogeneous nucleation which is one of the condition for lowering the temperature of mullite formation. Besides, fluorine addition could change the mullite gel structure (by changing the rate of hydrolyses of silica and it could change the content of bonded water during gelling), which should be very important for the temperature of mullite formation, too. The experimental results of heat treated gels showed that the addition of fluorine ion does decrease the temperature of mullite formation (in respect to classical sol-gel mullite processing) up to 8900C. As a nucleant in this study the mullite powder by “seeding” process contribute to muillite gel formation that after heat treatment up to 10000C showed very fine microstructure.
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Lima, Samantha Pinheiro Buás de. „Estudo da Produção e Aplicação em Pastas Cimentícias de Sílica Gel Proveniente das Cinzas da Casca do Arroz“. Universidade Federal do Amazonas, 2009. http://tede.ufam.edu.br/handle/tede/3483.
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The experimental program of this research was developed in order to evaluate the silica gel performance in cement based pastes. Thus, parameters of silica gel from rice husk ash were studied extraction. The incorporation of silica gel was made by the partial replacement of 0%, 2,5% e 5% of the cement mass in 0,45 water-cementitious material (w/cm) paste, and 0%, 5%, 7% in 0,5 w/cm paste. The silica gel behavior was evaluated based on X- ray diffraction, thermal analysis and compressive strength after 3, 7 and 28 days of curing. The results showed that is possible the production of pastes with excellent mechanical performance from the silica gel application as pozzolan. In particular, the compressive strength of the silica gel paste was about 46% higher than the reference paste. Moreover, there was a decrease of the more than 50% of calcium hydroxide content in the silica gel paste, indicating the pozzolanic activity of the silica gel produced in this work.
O programa experimental realizado no presente projeto foi desenvolvido de forma a avaliar o desempenho da sílica gel em matriz de cimento Portland. Para tal, foram estudados os parâmetros de extração da sílica gel da cinza da casca de arroz. O gel de sílica foi aplicado em pastas como substituto parcial do cimento Portland nos teores de 0%, 2,5% e 5% em massa, para uma relação água-aglomerante de 0,45, e de 0%, 5%, 7% em massa, para uma relação água-aglomerante de 0,50. O comportamento da sílica gel foi avaliado através de ensaios de difração de raios-x, análise térmica e resistência à compressão nas idades de 3, 7 e 28 dias. Os resultados indicaram que é possível a produção de pastas de excelente desempenho mecânico a partir da aplicação de sílica gel como pozolana. Em particular, a sílica gel promoveu um aumento da resistência à compressão de até 46% aos 28 dias e consumiu mais de 50% do hidróxido de cálcio, fato que se atribui a elevada atividade pozolânica da sílica gel.
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Pohl, Annika. „Sol−Gel Synthesis of CMR Manganites“. Doctoral thesis, Uppsala University, Department of Materials Chemistry, 2004. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-3970.
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The development of more advanced materials forms the basis of technological progress. One group of fascinating compounds with many potential applications in spintronic devices are the mixed-valence perovskite manganites. These have attracted considerable interest during the last decade through their very large magnetoresistance near the Curie Temperature. Although the properties of a material determinie any application, the development of reliable and flexible synthesis methods is crucial, as is the understanding of these methods. Knowledge of how different materials are formed is also of general importance in tailoring new materials. The aim of this project has therefore been not only to develop a new synthesis route, but also to understand the mechanisms involved.
This thesis describes the synthesis and characterization of a novel manganese alkoxide and its use in sol–gel processing of magnetoresistive perovskite manganites. In searching for a soluble manganese alkoxide for sol–gel processing, we found that the methoxy-ethoxide, [Mn19O12(moe)14(moeH)10]·moeH, has a high solubility in appropriate organic solvents. Being 1.65 nm across, it is one of the largest alkoxides reported; it is also of interest because of its (for oxo-alkoxides) rare planar structure. After mixing with La, Nd, Ca, Sr, and Ba methoxy-ethoxides, [Mn19O12(moe)14(moeH)10]·moeH was used in the first purely alkoxide based sol–gel processing of perovskites manganites. The phase evolution on heating xerogel powders to 1000°C was studied, and thin films were prepared by spin-coating.
It was found that the easily oxidised Mn-alkoxide facilitates the formation of high oxygen-excess modifications of the perovskites. The reactive precursor system yields fully hydrolysed gels almost without organic residues, but the gel absorbs CO2 from the air, leading to carbonate formation. The carbonate decomposition is the limiting step in oxide formation. Transport measurements of La0.67Ca0.33MnO3 films on LaAlO3 substrate show that all-alkoxide sol–gel derived films can compete with PLD films in terms of quality of epitaxy and transport. The somewhat different behaviour of the sol–gel derived films compared to PLD films is attributed to differences in morphology and oxygen stoichiometry.
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Gil, Mariana [Verfasser]. „Reward expectations in honeybees / Mariana Gil“. Berlin : Freie Universität Berlin, 2009. http://d-nb.info/1023582619/34.
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Chisham, Jason E. (Jason Edward). „Sol-gel materials for integrated optics“. Thesis, McGill University, 1996. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=23992.
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The sol-gel process is a low temperature solution route to amorphous and crystalline materials. Organic modification of the precursors allows the formation of organic-inorganic composite materials. We use the sol-gel process to produce an organically-modified ceramic for integrated optical applications. Photosensitive organic components allow the fabrication of passive integrated optical devices by photolithography. We demonstrate the fabrication and characterization of channel waveguides, waveguide devices and gratings in this material. Active devices based on the emission of erbium at 1.55 $ mu$m are under much investigation because of their potential use in telecommunications. Luminescence quenching is a major problem as an Er$ sp{3+}$ ion in its excited state transfers its energy to a nearby vibrational mode of its environment and decays non-radiatively to the ground state. Encapsulation of the ion into a coordination sphere to shield the ion from its surroundings may lead to reduced quenching. We synthesize several erbium tetrakis $ beta$-diketone complexes and dope them into different solvent environments and sol-gel hosts to probe guest-host interactions in the excited state.
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Sommerfeld, Andreia. „Untersuchungen zur Graphitkeimbildung in GJL-Schmelzen“. Clausthal-Zellerfeld Universitätsbibliothek Clausthal, 2010. http://d-nb.info/1000649415/34.
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Bent, Viktor van der. „Gil Vicente-do texto à ópera“. Master's thesis, Instituições portuguesas -- UL-Universidade de Lisboa -- -Faculdade de Letras, 2002. http://dited.bn.pt:80/29947.
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Stani´c, Vesha. „Sol-gel processing of metal sulfides“. Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq21641.pdf.
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Bellatone, Maria. „Sol-gel derived antimicrobial bioactive glass“. Thesis, Imperial College London, 2001. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.394943.
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Andrei, Diana Cristina. „The deformation of microscopic gel particles“. Thesis, Imperial College London, 1996. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.244158.
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Pethybridge, Guy David. „Sol-gel processing of dielectric ceramics“. Thesis, University of Oxford, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.318872.
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Lloyd, Gareth Owen. „Anion-tuning of supramolecular gel properties“. Thesis, Durham University, 2010. http://etheses.dur.ac.uk/186/.
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Low molecular weight gelators (LMWGs) are a class of compounds that has garnered great interest from material, synthetic, supramolecular and biological chemists. Anion tuning of these supramolecular gels is a burgeoning field of study. Two classes of compounds, chiral bisureas and urea derivatised pyrazoles are studied. The synthesized chiral bisurea compounds act as gelators in a variety of solvents. Addition of anions in the form of tetrabutyl ammonium salts was found to afford break up of the gels. Studies reveal that the rheological characteristics of these materials can be tuned using the simple addition of sub-stoichiometric amounts of anion. Variation in the length of the alkyl chain of the spacer separating the chiral and bisurea moieties affects the gel formation of a series of related compounds. Compounds with even numbered spaced alkyl chains were found to gel, whereas the odd numbered spaced alkyl chain compounds did not. Crystal growth within the gel matrix influences the crystallization processes and the use of anion induced break down of the LMWGs allows for easy recovery of the grown crystals. Drug compounds, bound upon gelation of a solution containing the drugs, were found to be released in a controlled manner from the gel matrix. Urea functionalised pyrazoles were synthesized. Crystallographic determination of the hydrogen bonding of the compounds as well as the coordination chemistry of these compounds was obtained. Anion binding studies, in addition to the crystallographic results, reveal that the urea or thiourea groups form an intramolecular hydrogen bond with the pyrazole group resulting in an anti conformation. This prevents formation of gels except in one case. The gelation of 1-(3-methyl-1H-pyrazol-5-yl)-3-(3-nitrophenyl)urea in acidic water overcomes this problem by protonation of the pyrazole group resulting in a syn conformation of the urea group. Anion tuning of the gel properties is revealed where nitrate and chloride result in precipitation of gels and the rheological characteristics can be tuned by changing the anion’s identity.
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Michieletto, Davide, Davide Marenduzzo, Gareth P. Alexander, Enzo Orlandini und Matthew S. Turner. „Ring polymers diffusing in a gel“. Universitätsbibliothek Leipzig, 2015. http://nbn-resolving.de/urn:nbn:de:bsz:15-qucosa-182706.
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Mogili, Sravya. „Sol-Gel Synthesis of Aluminosilicate Glasses“. Thesis, Southern Illinois University at Edwardsville, 2015. http://pqdtopen.proquest.com/#viewpdf?dispub=1584733.
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The main goal of this research project is to synthesize aluminosilicate glass materials that are doped with praseodymium. To be useful for optical studies, these glass materials must be optically transparent, strong enough to be handled and polished, and free of cracks. An advantage of the sol-gel process is that we have control over the amount of doping. However, a disadvantage of the sol-gel process is that cracking often occurs during the drying step.
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Blyth, David John. „Optical biosensing using sol-gel technology“. Thesis, University of East Anglia, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.338063.
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Meegan, Jonathan E. „Sol gel synthesis of organised matter“. Thesis, University of Leeds, 2005. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.417746.
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Hadjem, Abdenour. „Traitement d'image du gel d'électrophorèse bidimensionnelle“. Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb37614129j.
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Adetola, Opeyemi. „Immobilization of Heteropolyacids in Silica Gel“. Digital Commons @ East Tennessee State University, 2016. https://dc.etsu.edu/etd/3050.
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Silica gels containing incorporated heteropolyacids (HPAs) were synthesized in acidic media by co-condensation of tetraethoxysilane (TEOS) with phosphotungstic or phosphomolybdic acids using sol-gel technique. Effect of the synthesis conditions on their structure and morphology was studied. Yields of modified materials were some lower as compared to non-modified silica gels. All materials were mesoporous but contained micropores in their structures. Presence of bands of Keggin’s structures in FT-IR spectra along with absence of XRD patterns of crystalline HPAs confirmed their fine incorporation into silica network. Particle sizes of modified materials were 800-1100 nm excepting for W-containing sample obtained with trimethylstearylammonium chloride. This unusual effect was attributed to stabilization of primary silica nanoparticles by interaction between surfactant and HPA. High ratio HPA/TEOS resulted in partial loss of porosity. Obtained results might be used for optimization of synthesis of effective catalysts and adsorbents containing HPAs in mesoporous structure.
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Karg, Matthias. „Fluorolytische Sol-Gel-Synthese von Magnesiumfluorid“. Doctoral thesis, Humboldt-Universität zu Berlin, Mathematisch-Naturwissenschaftliche Fakultät, 2015. http://dx.doi.org/10.18452/17292.
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Die vorliegende Arbeit befasst sich mit mechanistischen Untersuchungen der fluorolytischen Sol-Gel-Synthese von nano-Magnesiumfluorid, sowie verschiedenen Abwandlungen der bekannten Synthese zur gezielten Veränderung der Eigenschaften der erhaltenen Materialien. Es werden die drei im folgenden beschriebenen Themenbereiche behandelt: Der Verlauf der Fluorolyse von Magnesiummethoxid mit methanolischer HFLösung wird mit der 19F-NMR-Spektroskopie über sechs Monate untersucht. Es wird gezeigt, dass MgF2-Nanopartikel, Agglomerate von gestörten MgF2-Partikeln und nicht umgesetzte, adsorbierte HF-Spezies in den Solen nachweisbar sind. Erstmalig werden MAS-NMR-Experimente an Solen beschrieben. Zusätzlich wird die schrittweise Fluorolyse von MgCl2 mittels NMR-Spektroskopie und XRD untersucht. Es werden drei verschiedene Synthesewege vorgestellt, mit denen eine Veränderung von Partikel- oder Kristallitgrößen erreicht wird. Eine sequentielle Synthese ermöglicht die Vergrößerung der Agglomerate im Sol. Das Erhitzen eines Sols zum Sieden unter Rückflusskühlung führt zu einem geringfügigen Anwachsen der Kristallitgröße. Durch Solvothermal-Synthesen wird eine signifikante Vergrößerung der Kristallite erzielt. Der Einfluss verschiedener Reaktionsparameter wird untersucht. Der Einfluss von MgF2 auf die Kristallisation von amorphem TiO2 wird untersucht. Es wird gezeigt, dass die Sol-Gel-Synthese von TiO2 in Gegenwart eines MgF2-Sols (min. 5 mol%) zur Kristallisation von Rutil-TiO2 bei vergleichsweise niedrigen Temperaturen führt. Verschiedene alternative Synthesen werden vorgestellt, durch die bei vergleichbaren Bedingungen nur Anatas-TiO2 erhalten werden kann. Ein möglicher Mechanismus der Strukturinduktion wird vorgeschlagen.The present Ph.D. thesis deals with mechanistic investigations of the fluorolytic sol-gel synthesis of nano magnesium fluoride. Furthermore, variations of the well known synthesis are introduced. The aim of these variations is to tailor the properties of the synthesized materials. The thesis covers three main chapters briefly introduced below: The course of the fluorolysis of magnesium methoxide with methanolic HF-solution will be monitored for six months using 19F NMR spectroscopy. The existence of MgF2 nanoparticles and agglomerates of disturbed MgF2 particles will be proven. It is demonstrated that hydrogen fluoride does not react immediately after the addition of HF-solution. For the first time MAS-NMR experiments of sols will be conducted. Furthermore, stepwise fluorolysis of magnesium chloride will be followed by NMR spectroscopy and X-ray diffraction. In this case no intermediates will be detected. Three different synthetic approaches capable of tailoring the crystallite and particle sizes will be presented. Using a sequential synthesis leads to increased size of the agglomerates in the sols. It will be demonstrated that heating and refluxing of a sol increases the crystallite size slightly. Solvothermal synthesis will be the last method leading to significant increase in crystallite sizes. Several synthetic parameters will be varied to identify their influence on the received crystallites. The influence of nano MgF2 on the crystallisation of amorphous TiO2 is investigated. It will be shown, that the sol-gel synthesis of TiO2 in the presence of a MgF2 sol leads to the crystallisation of the rutile polymorph of TiO2. The temperature treatment for that is comparatively low and just 5 mol% MgF2 are necessary. Furthermore, a different alternative synthesis will be introduced, that gives the anatase polymorph at the same conditions. Eventually a possible mechanism for the structural induction is proposed.
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Wang, Changnan. „Gel phase transition and molecular recognition“. Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/43921.
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