Spontaneous expulsion of various forms and types of matter from their solid substrates has always been an integral part of interfacial physics problems. A thorough understanding of such interactions between a solid surface and different soft materials not only expands our theoretical knowledge, but also has applications in self-cleaning, omniphobic surfaces and phase-change heat transfer. Although there is a renewed interest in the design of robust functional surfaces which can passively remove highly viscous liquids or dew, or retard ice accretion or frost formation, the physics of several dewetting and/or deicing mechanisms are yet to be fully understood. Even though we know how jumping-droplet condensation offers significantly better heat transfer performance than regular dropwise condensation and can liberate foreign particles, fundamental questions on the effect of surface orientation on jumping-droplet condensation or how it helps in large-scale fungal disease epidemic in plants are still unanswered. Thus, we first try to fill the knowledge gap in jumping-droplet condensation by characterizing their orientation-dependence and their role in a large-scale pathogenic rust disease dissemination among wheat. Unfortunately, understanding of such dewetting mechanisms does not necessarily translates to prevention or removal of ice and frost on subzero surfaces. Use of superhydrophobic structures or hygroscopic materials to retard the growth of frost was found to be limiting. Therefore the search for an efficient, inexpensive, and environmentally favorable anti-icing or de-icing mechanism is still underway. Here we give a framework for making a novel de-icing construct by analyzing a peculiar jumping frost phenomena where frost particles spontaneously jump off the surface when a polar liquid is brought above. Lastly, we demonstrate a simple and cost-effective technique to design a slippery liquid-infused surface from low-density hydrocarbon-based polymers, which is able to effectively remove a wide variety of soft materials. The main all-encompassing theme of this dissertation is to enhance our understanding of several dewetting phenomena, which might enable better design and/or mitigation strategies to control the expulsion of various forms of matter from a wide variety of surfaces. / Doctor of Philosophy / A few years back, a laundry detergent company in India came up with a famous ad campaign; it showed kids coming home from school with dirt all over their clothes to face the wrath of their parents. Rather than casually disparaging their mischievousness, the ad would make us think with their tagline: "Agar daag (Lit. stain, Fig. mess) lagne se kuch achha hota hain, toh daag achhe hain na? (Fig. If something good comes out of a mess, is it a mess?)". While this presents to us an excellent philosophical conundrum, in reality, we always find ways to get rid of foreign materials from surfaces of everyday use. Using water or dirt-repellent coatings on our shoes/clothes/car windshields or in worst case, spending hours trying to clean frost off our cars is something we are all familiar with. Finding innovative ways to remove unwanted materials from surfaces is not limited to humans, but also exhibited by various natural organisms. The excellent water repellency of lotus leaves, antifogging abilities of mosquito eyes or cicada wings, and slipperiness of pitcher plants are just few examples of natural self-cleaning surfaces designed to keep foreign materials or dew droplets off the surface. Sometimes we take a leaf or two out of these natural designs to help our cause. Surfaces with extreme water repellency are called superhydrophobic (hydro: water, phobos: fear). For a long time, gravity was considered to be the only passive droplet removal mechanism on these surfaces. About ten years ago, researchers found out that when two or more small dew droplets come together on these surfaces, they jump off the surface. Compared to the gravity removal, much smaller droplets can be removed via this method resulting in better anti-fogging qualities and heat transfer performance on the surface. As the jumping droplet event itself is independent of gravity, it was long assumed that the performance of these surfaces would not be dependent on their orientation. These jumped droplets can also take off with contaminating particles by partially or fully engulfing them. A recent study has brilliantly showed how rust spores are liberated from the superhydrophobic wheat leaves via jumping dew droplets. This fundamentally new mode of pathogen transport is yet to be fully understood at the same scale as we know wind or rain-induced fungal spore transport. In this work, we try to fill the knowledge gap by answering questions such as whether the surfaces with the abilities of gravity-independent jumping-induced droplet removal ironically fail to gravity and how far can spore(s) travel engulfed in a jumped droplet. But it is not just water droplets (or particles collected by water droplets) on a surface that we want to get rid off. The solid phase of water, i.e., ice or frost, when formed on regular surfaces, is actually harder to remove. The common ice-preventing surfaces are generally unable to stop complete frost formation and forces us to use salt or other moisture attracting chemicals to remove ice from a surface, knowing very well what is the economic and environmental cost of these chemicals. Here, we have introduced a novel de-icing mechanism by holding only a drop of water over a sheet of frost. The simplicity of our experimental setup may remind you the home physics experiments we all did in our childhood. We finish our discussion by designing a slippery surface from regular polymer films used in food packaging. Although the idea behind these slippery surfaces has been around since 2011, polyethylene films have never been used to make such surfaces before. Here, we show through extensive characterization that by choosing a suitable lubricating oil and a polyethylene-based film, we can finally get all of our ketchup to slide out of their packets, without struggle. If the future design of superhydrophobic condensers, de-icing constructs, or slippery surfaces benefit from the work reported here, may be I can finally say with certainty, "Daag Achhe Hain (Dirt is good.)."

Nanocellulose is an interesting natural material thatis gaining interest in the field of materials science, particularly nanocomposites. Depending on the disintegration route, nanocellulose can be isolated either in the form of long and flexible fibres (nanofibrillated cellulose, NFC), or stiff, rod-like crystals (cellulose nanocrystals, CNC). Nanocellulose can be utilized in nanocomposites either as a reinforcement element or as a network matrix due to its ability to form a strong network. In this thesis, nanocellulose based materials are prepared by evaporation of a liquid medium. The key step in this processing route is a good dispersion of the nanoparticles in the selected matrix. Therefore the importance of surface modification in order to ensure favourable nanocellulose dispersion is clarified in avariety of materials systems. In Paper I, poly(methyl methacrylate) (PMMA) based fibres prepared by electrospinning were reinforced with nanofibrillated cellulose. Native NFC appeared to show a good compatibility with PMMA matrix in the electrospinning solution and resulting fibres. Furthermore, a new method for mechanical testing of mats with random fibre orientation as well as aligned fibres was developed. In Paper II, commingled nanopaper structures with carbon nanotubes (CNTs) were prepared. Several surfactants were used to disperse hydrophobic CNTs in water. A nonylphenol phosphate ester (NPPE) was found to work well for both dispersing CNTs in water and providing compatibility with NFC through electrostatic repulsion between the phosphate ester groups of the surfactant and the carboxylate groups of NFC. In Paper III, a new water based route for functionalization of cellulose nanocrystals was developed. In this approach, inspired by organo-modified layered silicates, quaternary ammonium salts were adsorbed. It was demonstrated that different functionalities (alkyl, phenyl, glycidylor diallyl) can be introduced onto the cellulose and the dispersibility in organic solvents was studied. Subsequently, in Paper IV, nanocomposites with poly(vinyl acetate) (PVAc)were prepared. The effect of modification on the degree of dispersion of the CNC within the matrix was studied as well as the strong effects on the properties of the resulting nanocomposites. In Paper V, taking advantage of the entangled NFC network and the possibility to tailor the pore size and surface chemistry, lubricant-infused slippery films and coatings based on NFC were prepared for the first time. / <p>QC 20131016</p>

Superhydrophobic (SHS) and lubricant-infused surfaces (LIS) exhibit exceptional non-wetting characteristics that make them attractive for energy production applications including steam condensation and fouling mitigation. The dissertation work focuses on application of non-wetting surfaces to energy production using a systematic approach examining each component of surface fabrication in three functional areas. First, SHS and LIS are fabricated using robust, scalable methods and tested for durability in heated, wet conditions and under high-energy water jet impingement. Clear performance differences are shown based on surface texturing, functionalizing agent, and infused lubricant. Second, SHS and LIS are applied to tube exteriors and evaluated for their ability to produce sustained dropwise condensation in a typical power plant condenser environment. The surfaces are shown to produce heat transfer coefficients up to 7-10 times that of film-wise condensation, with condenser effectiveness of 0.92 or better compared to effectiveness of about 0.6 in conventional condensers. Third, LIS on the interior of tubes are assessed in accelerated mineral fouling conditions. LIS are shown to mitigate calcium sulfate and calcium carbonate fouling under laminar conditions. The results of the study bear profound benefits to reducing the levelized cost of condensers and water uptake in thermoelectric power plants, that currently consume about 50% of the total water use in the U.S. / Doctor of Philosophy / Creating durable, hybrid surfaces for improved steam condensation and fouling mitigation would provide substantial impact to power generation worldwide. Bioinspired, non-wetting surfaces, such as superhydrophobic (SHS) and lubricant-infused surfaces (LIS) exhibit exceptional non-wetting characteristics that make them attractive for energy applications. Each of these non-wetting technologies, however, faces durability and scalability challenges that make them unfeasible for widespread, practical adoption. As a result, decades of materials science research have stagnated in the research laboratories with limited demonstrations of dropwise condensation and fouling mitigation in static situations. The dissertation work focuses on application of SHS and LIS to energy production using a systematic approach examining each component of surface fabrication in three functional areas. First, SHS and LIS are fabricated using robust, scalable methods and tested for durability using ASTM standard static and dynamic evaluation methods. Clear performance differences are shown based on surface texturing, functionalizing agent, and infused lubricant. Second, dropwise steam condensation on the surfaces are shown to exhibit heat transfer performance an order of magnitude greater than film-wise condensation in a typical power plant condenser environment. The surfaces are shown to produce heat transfer coefficients up to 7-10 times that of film-wise condensation, with condenser effectiveness of 0.92 or better compared to effectiveness of about 0.6 in conventional condensers. This work presents for the first time, a non-dimensional correlation for a priori prediction of LIS heat transfer performance given known qualities of the LIS. Third, challenges of fouling mitigation in power plants have been studied for over a decade. This work demonstrates for the first time that LIS applied to the interior of tubes mitigate calcium sulfate and calcium carbonate fouling in both static and laminar flow conditions.

A tese tem por objeto as noções de virtude adquirida e de virtude infusa na obra de Tomás de Aquino, e pretende defender uma leitura integracionista da ética de Tomás, segundo a qual a os conceitos de virtude, lei e graça formam um conjunto harmônico e têm, entre si, relações de dependência recíproca. As virtudes adquiridas por atos humanos tornam-se inteligíveis à luz do conceito de sindérese e dos primeiros princípios da lei natural. As virtudes infusas são explicadas como efeitos da graça e da lei divina. O conceito de habilidade (habitus) é analisado como o gênero das virtudes e ajuda a resolver objeções contra os dois tipos de virtudes. Prova-se que a causação das virtudes adquiridas e das virtudes infusas segue uma estrutura espelhada, que tem Deus como causa eficiente remota, por meio dos princípios exteriores da lei e da graça. A origem exterior, porém, não compromete a natureza da virtude como perfeição interior, em ambos os casos, graças ao conceito de habilidade. A leitura integracionista é concluída com a subordinação das virtudes adquiridas ordenadas a uma felicidade imperfeita às virtudes infusas, que têm a felicidade perfeita como objeto e fim. / The thesis analyses the notions of acquired and infused virtue in the work of Thomas Aquinas in order to present an integracionist reading of his ethics, by which concepts like virtue, law and grace are treated as parts of a harmonic set, having reciprocal relations among each other. The idea of virtues acquired by human acts becomes intelligible in the light of the concept of synderesis and the first principles of natural law. Infused virtues are understood as effects from grace and divine law. The concept of hability (habitus) is analysed as the gender of all virtue and helps to resolve objections raised against both kinds of virtue. It proves that the causation of virtues, acquired and infused, follows a simetrical sctructure in which God works as the remote efficient cause, by means of the external principles of law and grace. However, the external provenance of these principles does not jeopardise the virtue’s character as an interior perfection, in both cases of acquired and infused virtue, thanks to the concept of hability. The integracionist reading ends with the subordination of the acquired virtues that aims to an imperfect happiness to the infused virtues that have perfect happiness as their proper object and goal.

No description available.

Children’s experiences are the cornerstone of all that matters in elementary schools. It is therefore the purpose of this study to shed further light into what those experiences might be, particularly as they are present in arts-infused education. Over a period of almost two school years I followed a group of primary grade students in and out of their classrooms at Central Arts Elementary School in an urban mid-Western Canadian school district. Through conversation, recordings, artwork, scripts, and visual images, as teacher-researcher-artist, I collected a series of moments that I believe best describes the nature of these students’ experiences in arts-infused education. Concepts of identity, place, imagination, and self were explored. I considered the lived curriculum of the classroom, and also the ways in which the children’s experiences with the arts resonated alongside my own artistic endeavours. The study is a multi-method inquiry informed by arts-based, narrative, and ethnographical research practices. There are elements of ethnodrama, in the ways in which some events are portrayed through scripted descriptions in a concluding chapter of the work. Children’s art, and the art of classroom life are revealed through both image and text. Puppets, masks, and a variety of other artistic media are brought forward for the purposes of consideration and discussion. In all, the work is unique in its attention to the words of children, and extended researcher engagement. Implications of the study include the importance of listening to children when they speak, continuing to offer the arts as pathways to greater awareness in schools, and considering children’s relationships as powerful mentoring experiences for one another.

A tese tem por objeto as noções de virtude adquirida e de virtude infusa na obra de Tomás de Aquino, e pretende defender uma leitura integracionista da ética de Tomás, segundo a qual a os conceitos de virtude, lei e graça formam um conjunto harmônico e têm, entre si, relações de dependência recíproca. As virtudes adquiridas por atos humanos tornam-se inteligíveis à luz do conceito de sindérese e dos primeiros princípios da lei natural. As virtudes infusas são explicadas como efeitos da graça e da lei divina. O conceito de habilidade (habitus) é analisado como o gênero das virtudes e ajuda a resolver objeções contra os dois tipos de virtudes. Prova-se que a causação das virtudes adquiridas e das virtudes infusas segue uma estrutura espelhada, que tem Deus como causa eficiente remota, por meio dos princípios exteriores da lei e da graça. A origem exterior, porém, não compromete a natureza da virtude como perfeição interior, em ambos os casos, graças ao conceito de habilidade. A leitura integracionista é concluída com a subordinação das virtudes adquiridas ordenadas a uma felicidade imperfeita às virtudes infusas, que têm a felicidade perfeita como objeto e fim. / The thesis analyses the notions of acquired and infused virtue in the work of Thomas Aquinas in order to present an integracionist reading of his ethics, by which concepts like virtue, law and grace are treated as parts of a harmonic set, having reciprocal relations among each other. The idea of virtues acquired by human acts becomes intelligible in the light of the concept of synderesis and the first principles of natural law. Infused virtues are understood as effects from grace and divine law. The concept of hability (habitus) is analysed as the gender of all virtue and helps to resolve objections raised against both kinds of virtue. It proves that the causation of virtues, acquired and infused, follows a simetrical sctructure in which God works as the remote efficient cause, by means of the external principles of law and grace. However, the external provenance of these principles does not jeopardise the virtue’s character as an interior perfection, in both cases of acquired and infused virtue, thanks to the concept of hability. The integracionist reading ends with the subordination of the acquired virtues that aims to an imperfect happiness to the infused virtues that have perfect happiness as their proper object and goal.

A tese tem por objeto as noções de virtude adquirida e de virtude infusa na obra de Tomás de Aquino, e pretende defender uma leitura integracionista da ética de Tomás, segundo a qual a os conceitos de virtude, lei e graça formam um conjunto harmônico e têm, entre si, relações de dependência recíproca. As virtudes adquiridas por atos humanos tornam-se inteligíveis à luz do conceito de sindérese e dos primeiros princípios da lei natural. As virtudes infusas são explicadas como efeitos da graça e da lei divina. O conceito de habilidade (habitus) é analisado como o gênero das virtudes e ajuda a resolver objeções contra os dois tipos de virtudes. Prova-se que a causação das virtudes adquiridas e das virtudes infusas segue uma estrutura espelhada, que tem Deus como causa eficiente remota, por meio dos princípios exteriores da lei e da graça. A origem exterior, porém, não compromete a natureza da virtude como perfeição interior, em ambos os casos, graças ao conceito de habilidade. A leitura integracionista é concluída com a subordinação das virtudes adquiridas ordenadas a uma felicidade imperfeita às virtudes infusas, que têm a felicidade perfeita como objeto e fim. / The thesis analyses the notions of acquired and infused virtue in the work of Thomas Aquinas in order to present an integracionist reading of his ethics, by which concepts like virtue, law and grace are treated as parts of a harmonic set, having reciprocal relations among each other. The idea of virtues acquired by human acts becomes intelligible in the light of the concept of synderesis and the first principles of natural law. Infused virtues are understood as effects from grace and divine law. The concept of hability (habitus) is analysed as the gender of all virtue and helps to resolve objections raised against both kinds of virtue. It proves that the causation of virtues, acquired and infused, follows a simetrical sctructure in which God works as the remote efficient cause, by means of the external principles of law and grace. However, the external provenance of these principles does not jeopardise the virtue’s character as an interior perfection, in both cases of acquired and infused virtue, thanks to the concept of hability. The integracionist reading ends with the subordination of the acquired virtues that aims to an imperfect happiness to the infused virtues that have perfect happiness as their proper object and goal.

No description available.

No description available.