Thesis (Ph. D.)--University of Virginia, 2006. / Includes bibliographical references (leaves 109-130). Also available online through Digital Dissertations.

Thesis (Ph. D.) -- Lincoln University, 2009. / Also available via the World Wide Web.

The novel grain refiners developed in this research could be broadly classified into borides and carbides. The motive behind choosing MgB2, AlB2 and their master alloys Mg-MgB2 and Mg-AlB2 as the grain refiners was driven by the crystallographic matching of the hexagonal borides with the magnesium crystal structure. Apart from this lightweight borides, denser borides such as CrB and WB have also shown excellent grain refinement in AZ91, AM50 and AZ31 alloys. It is suggested that the grain refinement effect in the magnesium alloys could be improved through a combined addition of bismuth along with the boride. The carbon based grain refiners were also explored as they are well-established for the grain refinement of aluminium containing magnesium alloys. The new carbon based grain refiners identified through this research are B4C, Mg-B4C, Mg-3Ti-1C. Magnesium matrix was chosen for the development of each of these master alloys to eliminate any impurity contamination during the grain refiner addition to the magnesium melt. The pressureless melt infiltration techniques was involved in the development of Mg-MgB2, Mg-AlB2 and Mg-B4C while, the ‘halide salt route’ was adopted for producing Mg-3Ti-1C master alloys. The application of ultrasonic cavitation for the development of a new Al-1.5B-2C master alloy was shown to be effective for a homogenous distribution of the intermetallic phases in the form of Al3BC. The potential heterogeneous nucleating sites proposed in the commercial aluminium containing magnesium alloys are MgB2 for Mg-MgB2 master alloy; Mg1-xAlxB2 (0.10 < x < 0.18) for AlB2 grain refiner; MgB2C2 for B4C grain refiner; CrB and WB for their individual powder additions respectively; Ti2AlC for Mg-3Ti-1C master alloy; Al3BC and Al4C3 for the Al-1.5B-2C master alloy.

Orientador: Americo Bortolazzo Correr / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-26T22:34:56Z (GMT). No. of bitstreams: 1 Araujo_TatianyGabrielleFreire_D.pdf: 2672056 bytes, checksum: dabae7d2ba0ca53d49bf01816863660a (MD5) Previous issue date: 2015 / Resumo: O objetivo neste estudo foi avaliar o efeito da adição dos solventes dimetil sulfóxico (DMSO) e tetrahidrofurano (THF) em propriedades físico-químicas de infiltrantes experimentais. Foram preparadas duas blendas resinosas, uma composta por 75%p de TEGDMA (T) e 25%p UDMA (U) e outra por 75%p de T e 25%p de BISEMA (B). Em um grupo de cada mistura não foi adicionado solvente. Os demais grupos foram formulados pela adição dos solventes DMSO ou o THF nas concentrações de 0,5% e 5%. No total foram obtidos 10 infiltrantes experimentais. Icon® foi utilizado como controle. Este estudo foi separado em 2 capítulos. No capitulo 1 o objetivo foi avaliar a influência dos solventes DMSO e THF no ângulo de contato, dureza Knoop em lesões artificiais de cárie infiltradas e a capacidade de penetração dos infiltrantes experimentais em microscópio confocal de varredura a laser. Os dados do ângulo de contato foram submetidos à analise de variância um fator e teste de Tukey, e os de dureza Knoop avaliados por analise de variância dois fatores e teste de Tukey (?=0,05). Os resultados mostraram que o Icon apresentou o menor ângulo de contato. Dentre os infiltrantes experimentais, o menor ângulo de contato foi apresentado pela mistura T + U + 5% DMSO, significativamente menor que as misturas T + U, T + U + 0,5% DMSO, T + U + 5% THF, T + B + 0,5% DMSO e T + B + 0,5% THF. Os resultados de microscopia confocal de varredura a laser mostraram que os infiltrantes apresentaram boa penetração nas lesões artificiais de cárie exceto os grupos T + B, T + B + 0,5% DMSO e T + B + 0,5% THF. As lesões infiltradas por Icon apresentaram dureza significativamente maior que dos outros materiais, exceto T + U + 0,5% DMSO (252,4) e T + U + 5% THF (239,1). Concluiu-se que o Icon apresentou os melhores resultados dentre os materiais avaliados, com menor ângulo de contato, maior dureza e boa penetração. Dentre os materiais experimentais, a incorporação de 5% de DMSO na mistura de U reduziu o ângulo de contato e apresentou dureza semelhante à infiltrada por Icon. No capitulo 2 foi verificada a influência dos solventes DMSO e THF nos infiltrantes experimentais no grau de conversão (GC) (n = 3), resistência coesiva à tração (RT) (n = 10), resistência de união a microtração (RU) (n = 10), resistência a flexão (RF) (n = 10) e módulo de elasticidade (ME) (n = 10). Os dados foram submetidos à ANOVA um fator e teste de Tukey (? = 0,05). Foi verificado que o GC dos infiltrantes com U foi significativamente maior que dos demais infiltrantes. Os infiltrantes experimentais sem solvente apresentaram RF significativamente maior que Icon e que os infiltrantes com solvente. Os infiltrantes com 5% de DMSO apresentaram RU significativamente menor que os demais; Icon apresentou RU significativamente maior que os demais infiltrantes. A RT de Icon foi significativamente maior que dos infiltrantes experimentais. Conclui-se que os solventes DMSO e THF não melhoraram a resistência de união e prejudicaram as propriedades mecânicas dos infiltrantes experimentais. Dentre os solventes, o THF na concentração de 0,5% apresentou menos efeitos deletérios nas propriedades mecânicas dos infiltrantes experimentais. Como conclusão geral, pode ser verificado que o infiltrante Icon apresentou os melhores resultados. Dentre os infiltrantes experimentais, o melhor desempenho foi obtido com a mistura T e U. A adição 0,5% do solvente DMSO na mistura T e U não reduziu o ângulo de contato e reduziu as propriedades mecânicas dos infiltrantes, mas produziu resistência de união e dureza da lesão infiltrada semelhante ao infiltrante Icon / Abstract: The aim of this study was to evaluate the effect of alternative solvents addition dimethyl sulfoxide (DMSO) and tetrahydrofuran (THF) in the chemical-physical properties of experimental infiltrants. Were prepared 2 blends: (1) 75wt% TEGDMA (T) + 25 wt% UDMA (U), (2) 75wt% T + 25wt% BISEMA (B). From each blend were added the solvents DMSO or THF in concentrations of 0.5wt% and 5wt%, totaling 10 experimental groups. Icon® was used as control. This study was divided in 2 chapters. In chapter 1 the aim was to evaluate the influence of alternative solvents (DMSO and THF) in the contact angle, Knoop hardness of artificial caries lesions infiltrated, and the capability of penetration of the experimental infiltrants. Data were analyzed by ANOVA one-way (contact angle) and two-way (Knoop hardness) and Tukey's test (?=0.05). The results showed that Icon presented the lowest contact angle. Analyzing the experimental infiltrants, T + U + 5% DMSO showed the lowest contact angle. The confocal microscopy analysis showed that the infiltrants presented satisfactory penetration into the caries-like lesions except the groups T + B, T + B + 0.5% DMSO and T + B + 0.5% THF. Lesions infiltrated with Icon exhibited hardness values significantly higher than all the experimental groups, except to T + U + 0,5% DMSO (252.4) e T + U + 5% THF (239.1). It is possible to conclude that Icon showed the best results for the tested properties. In chapter 2 was analyzed the influence of the addition of DMSO and THF solvents in experimental infiltrants in relation to degree of conversion (n=3), ultimate tensile strength (n=10), microtensile bond strength (n=10), flexural strength (n=10) and elastic modulus (n=10). Data were submitted to one-way ANOVA and Tukey's test (?=0.05). Infiltrants containing U obtained the highest degree of conversion values. The solvents-free experimental infiltrants showed the highest values of flexural strength. In relation to microtensile bond strength results, the groups with 5% DMSO presented the lowest results and Icon the highest ones. Icon group obtained the highest results of UTS. It is possible to conclude that the addition of solvents DMSO and THF did not improve the bond strength and affected negatively mechanical properties of the experimental infiltrants. THF solvent 0,5% showed less deleterious effects in mechanical properties of experimental infiltrants. Overall, Icon xi obtained the best results. Among the experimental infiltrants, the best performance was obtained by the association of T and U. The addition of 0.5% of DMSO in the blend T + U did not reduce the contact angle and affected negatively the mechanical properties, except to microtensile bond strength and hardness of the caries lesions infiltrated / Doutorado / Materiais Dentarios / Doutora em Materiais Dentários

Färskvatten är en naturresurs som alltmer hotas av antropogen påverkan och klimatförändringar. Idag försörjer kommunala dricksvattenverk majoriteten av Sveriges befolkning med dricksvatten producerat från yt- och grundvattentäkter. Pågående klimatförändringar medför utmaningar i att säkerställa en god dricksvattenförsörjning och innovativa lösningar undersöks ständigt. Regnvatteninsamling är en metod som använts långt tillbaka i tiden för att framställa dricksvatten. Dock har metoden under mänsklighetens modernare tid ansetts förlegad. I och med rådande problematik gällande vattenförsörjning i världen har regnvatteninsamling återvänt på många platser som icke-drickbar och drickbar vattenförsörjningskälla. Den här rapporten redovisar en studie av möjligheten att implementera regnvatteninsamling i två studieområden, studieområde A och B, på Muskö i Stockholmsskärgård. Syftet var att undersöka hur regnvatteninsamling på olika sätt kan bidra till att tillgodose vattenbehovet för framtida planerad bostadsbebyggelse på ön. I studieområde A undersöktes huruvida saltvatteninträngning till grundvattenmagasin förekom samt möjligheten till infiltration av insamlat regnvatten till grundvattenmagasin i syfte att förhindra saltvatteninträngning. I studieområde B undersöktes hur stora mängder vatten regnvatteninsamling från takytor teoretiskt skulle kunna bidra med till beräknat vattenbehov. Framtida klimat togs i åtanke och kvantiteten regn som i framtiden kommer falla i området bestämdes från två RCP, representative concentration pathways, klimatscenarion RCP4.5 och RCP8.5. RCP4.5 utgår från att koldioxidutsläppen kulminerar år 2040 medan RCP8.5 utgår från fortsatt höga koldioxidutsläpp. Beräkningar med antagande RCP4.5 påvisade att 117 000 m3 regnvatten per år teoretiskt kan insamlas från avrinningsområdet i studieområde A och ledas till grundvattenmagasinet för infiltration. Med antagande RCP8.5 anses maximalt 169 000 m3 regnvatten kunna insamlas till infiltration. Dock kunde konstateras att det med undersökta pumpflöden inte förekom saltvatteninträngning till akviferen och infiltration anses därför inte nödvändig i undersökt studieområde. Från takytor beräknades med RCP4.5 insamlat regnvatten kunna bidra med 8 % till vattenförbrukningen per hushåll, med RCP 8.3 beräknas regnvatten kunna bidra med 9 % av bedömd vattenförbrukning.

The infiltration of nanoparticle electrocatalysts into solid oxide fuel cell (SOFC) electrodes has been proven to produce a high density of electrochemically active sites, and reduce charge transfer polarization losses in SOFC electrodes. This is crucial for intermediate temperature operation, as these losses increase greatly at lower temperatures. Nickel-yttria stabilized zirconia (Ni-YSZ) cermets are low-cost, and exhibit excellent stability, but their main disadvantage stems from nickel coarsening and performance loss over their operational lifetimes. Infiltration of electrocatalyst nanoparticles has been shown to mitigate nickel coarsening and the consequent anode degradation. In this work, the effects of these infiltrants have been observed in a standard Ni-YSZ electrode. In addition to nickel, mixed ionic and electronic conducting (MIEC) phases have been infiltrated into Ni-YSZ scaffolds and their performance characterized using electrochemical impedance spectroscopy (EIS). Cross-sectional microscopy of fractured cells has been used to compare electrode microstructure and particle statistics. A model has been proposed to explain the origin of anode performance enhancement from nanoscale electrocatalysts.

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The following document serves as a design guidebook to assist landscape architects, designers, planners, engineers, and architects in the practice of developing land while preserving water quality. This guidebook outlines methods for maximizing permeable surfaces by providing examples of ways to minimize impervious surfaces. / Master of Landscape Architecture

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