<p>This dissertation draws on the virtue ethics tradition in moral theology and moral philosophy for inquiries regarding the acquired and infused virtues, virtue's increase and remission, and virtue's relation to sacramental practice. I rely on two medieval texts to ask and answer these questions: the <italic>Summa Theologiae</italic> by Thomas Aquinas and <italic>Piers Plowman</italic> by William Langland. My arguments are primarily inter- and intra-textual with some attention to the texts' history of interpretation and the socio-historical Catholic culture in which they were written. I conclude that the texts share pedagogical features that teach their readers in what the perfection of virtue consists and show readers how to increase in that perfection.</p><p>This thesis follows from the work of David Aers, Stanley Hauerwas, Alasdair MacIntyre, Josef Pieper, and Eberhard Schockenhoff.</p> / Dissertation

Beams are ubiquitous in our everyday life and can be found in a variety of length scales, from large supports of buildings to carbon nanotubes. Similarly, bubbles can also span a variety of scales, ranging from tiny bubbles in a glass filled with champagne to the giant soap bubbles formed by artists to attract crowds. Yet, the behavior of beams and bubbles can often occur so fast that the dynamics go unnoticed. This dissertation aims to understand the mechanics of beams and bubbles in four different examples. We combine table-top experiments with mathematical models to predict how each system will behave when exposed to different extreme conditions. We start by examining the retraction of a rubber band once it has been stretched and released. This process is similar to plucking a string, where the dynamics are governed by tensile and inertial forces, resulting in a trapezoidal shape during retraction. However when a rubber band is stretched and released, a region of high-curvature develops. Our experiments and mathematical model highlight that bending forces can be significant and give rise to a curved self-similar shape to the retracting rubber band. The next example involves the competition of surface tension and twisting on a flexible rod. Most studies in the field of elasto-capillarity have focused on how surface tension can bend an elastic structure, leaving the possibility of twisting unexplored. Here we utilize particles with discrete wettabilities -- or Janus particles -- at liquid interfaces that can be used to twist a flexible cylinder. The third system is focused around the spreading behavior of bubbles on submerged surfaces coated with a layer of oil. These liquid-infused surfaces have remarkable applications due to their ability to minimize contact line pinning. However, this property has mostly been exploited using liquid drops. We here study the early spreading behavior of a bubble once it has made contact with the liquid-infused surface. The final chapter is centered around the collapse of bubbles resting on the surface of an ultra viscous liquid. When a bubble on such a surface is ruptured, the bubble film collapses vertically downwards, leading scientists to believe that gravity is driving the collapse. Yet, interfacial forces are dominant in highly curved liquid surfaces and exceed gravitational forces. By turning the setup upside-down, we show that surface tension is indeed responsible for the collapse and the subsequent wrinkling instability that develops.

Non-wetting surfaces offer enhanced capabilities over bare metal substrates for condensation with or without phase change. This trait can be utilized to broaden strategies in combating water scarcity in water stressed areas. Slippery lubricant infused surfaces have the ability to shed water droplets with lower nucleation times, taking advantage of more of the limited amount of time available to collect dew and fog than traditional surfaces. However, existing studies focus on short durations with scant information available on the longer-term performance or durability of the materials in application environments. To address this knowledge gap, dew harvesting studies were conducted over a 96 hour period on a lubricant infused surface vis-à-vis regular surface of the same material. Three phases of performance are identified and discussed with regard to the water harvesting potential. The second part of the thesis addresses water condensation under conditions where freezing is a potential issue. Non-wetting surfaces have been shown to be a promising method of limiting the formation of ice from sessile droplets. This study explores the effect of surface roughness on the freeze time of sessile water droplets. Superhydrophobic and hydrophobic, lubricant infused, copper surfaces were created via electrodeposition and chemical etching in conjunction with chemical treatments to achieve non-wetting surfaces of varying surface textures. Freezing characteristics on the surfaces are studied experimentally and, for the first time, computationally, wherein the surface is described using a fractal surface topography. The effect of surface engineering on the freezing dynamics and comparison between the experimental and the computational studies are elucidated. / Master of Science / The use of durable, water repelling surfaces that are also thermally conductive provide an opportunity to help alleviate strain from a growing world crisis, water scarcity. Lubricant infused surfaces shed water from their surface by providing a slippery layer for the droplets to slide on, as opposed to bare metal which water tends to cling to. This behavior makes lubricant infused surfaces attractive as a water harvesting method. However, these surfaces degrade over time and must be maintained to perform at their maximum capability, collecting water for 40 minutes more than a bare surface. This thesis focuses on the performance of these surfaces over a 96-hour operating period to characterize the effect lubricant drainage has on the water collection behavior. Freezing water droplets, commonly referred to as icing, poses concerns for safety and operational ability in industries like renewable energy generation, where icing limits efficiency. Non-wetting surfaces have a unique ability to inherently slow down the phase change of a water droplet to ice due to the lower contact area of droplets resting on the surface. This thesis examines superhydrophobic and lubricant infused surfaces of varying degrees of roughness to explore the effect that the contact angle and different surface structures have on the freezing rate of water on the surface. The experimental results are compared to numerical simulations, which is useful in designing systems that would implement this passive icing mitigation technique.

Slippery liquid-infused porous surfaces (SLIPS) – a new class of bio-inspired liquid-repellent surfaces – comprise arbitrarily porous architectures filled with oils that exhibit high interfacial tensions to probe liquids and present ultralow contact angle hysteresis (<〖10〗^°). However, before practical technologies based on SLIPS can be designed at large-scale, a number of fundamental questions remain to be answered. For instance, depending on the sign of the spreading coefficient of the Vapor(V)-lubricant oil(O)-liquid(L) system, defined as S_(OL(V))=γ_LV-γ_LO-γ_OV>0, the lubricating layer forms a layer at the liquid-vapor interface (here, γ_LV is a liquid-vapor interfacial tension, γ_LO – liquid-oil, and γ_OV – oil-vapor). This “cloaking” of liquid drops can deplete SLIPS’ lubricant over time and contaminate the probed liquid. So far, cloaking has been investigated by contact angle goniometry and confocal microscopy, which cannot resolve films of molecular thickness and factors that govern the equilibrium thickness of those films are not entirely clear. Here, we report on the development and application of a reflective-mode SFA platform to characterize the cloaking of water droplets placed on SLIPS. A multilayer matrix method is utilized to analyze the interferometry data. Using this complementary experimental and analytical approach, we determined the thickness of the cloaking layer for the FDTS(solid)-VF-40(lubricant)-water(probe liquid)-air system to be z3= 7±1 nm. Towards deeper insights into the intermolecular and surface forces responsible for cloaking, we demonstrate that repulsive van der Waals interactions are responsible for stabilizing the cloaking film at the water-air interface. Our experimental platform and the analytical framework should facilitate investigations of other SLIPS and probe liquid systems down to the molecular-scale resolution. These findings might aid the rational design of SLIPS, e.g., for drag reduction, anti-biofouling, and anti-corrosion. In addition to investigating SLIPS, We addressed the following questions with the help of atomic force microscopy (AFM): (i) how do zwitterionic osmolytes modulate electrostatic and hydrophobic interactions in nanoscale confinement, and (ii) is it possible to have two negatively charged surfaces attract each other? Our findings are presented as appendices in this thesis.

Material discovery and development has been playing a significant role in shaping human civilizations, by studying and improving materials for appealing observations to aid in our survival as well as to satisfy our curiosity. From the common earthly materials that give us strong building structures and hunting weapons to the Silicon Age that contributes to the creation of modern electronics and computers, the development of novel and enhanced materials continues to grow. Recently, a new field has emerged that is rapidly expanding the engineering circle; these are called nanomaterials. By shrinking bulk materials into structures with nanoscale dimensions, there is a deviation from classical physics, and quantum effects begin to dominate the properties of these materials. The nanometer range brings a high surface area-volume ratio which enhances the reactivity of the material, and thus size-dependent properties are materialized. Such behaviors can be applicable in several areas such as biomedical, catalysis, optics, processing, sensing and more. Nanomaterials can be further functionalized to grant new and enhanced functions, features and capabilities needed for a specific application. This dissertation aids to explore the functionalization of 1D and 2D nanomaterials for various applications. The proposed 1D and 2D nanostructures for testing will be polymer hydrogel nanofibers and silica nanoparticulate thin films, respectively. Nanofibers are unique by acting like swollen nanoreactors to enable functionalization via aqueous absorption and reaction. Silica nanoparticulate films have high nano-porosity, which can wet the thin coating intrinsically with aqueous and organic solvents or with non-organic solvents upon additional surface chemistry modification. In this dissertation, the functionalization of 1D and 2D nanostructures with chemical compounds and metal colloids will be tested, and the performance of the nanomaterials and nanocomposites for various applications will be evaluated.

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Surface science is a multidisciplinary subject which affects us on a daily basis. Surfaces are of particular interest because the chemical bonding and atomic structure is different at the surface compared to the bulk properties of a material. This interface is of great significance because it is where charge exchange, or new chemical bonds occur. One essential aspect of surface science is surface wettability, which can be harnessed to produce self-cleaning surfaces. This very lucrative notion, where surfaces with low adhesion to liquids, can result in quick and autonomous shedding, has inspired a multitude of device fabrication and implementation. Over the past decade, several self-cleaning surfaces have been fabricated from superhydrophobic surfaces, which depends on a stable interface between solid, liquid and gas. These surfaces, however, are restricted in their applications and fail to operate upon mechanical damage or nonhomogeneous fabrication processes. Recent advances in wettability science have produced omniphobic lubricant-infused surfaces (OLIS). These surfaces are created by tethering a liquid to a surface, providing a stable liquid interface, which results in excellent aqueous and organic liquid repellency, and high robustness toward physical damage. This thesis will encompass an overview of the classical models for surface wettability, new models for liquid mobility, the criteria required to obtain OLIS, as well as some of the biomedical engineering applications fabricated from this technology. Herein, a novel manufacturing process was developed to produce smooth channeled polymeric microfluidic devices from rough 3D printed molds. Additionally, we integrated OLIS technology with electroconductive sensors to create high surface area electroactive material with self-cleaning properties, ideal to combat non-specific adhesion of biomolecules. Furthermore, our fabrication methods are inexpensive and have the potential to be easily integrated into manufacturing processes to create highly functional microfluidic devices, optimal for lab-on-chip diagnostic platforms. / Thesis / Master of Applied Science (MASc) / Recent advances in wettability science have produced omniphobic lubricant-infused surfaces (OLIS) inspired by the Nepenthes pitcher plant. These surfaces are created by tethering a liquid to a surface, providing a stable liquid interface, which results in excellent aqueous and organic liquid repellency, as well high robustness toward physical damage and high pressure dispensing scenarios. The motivation for this thesis is to expand on the applications for OLIS devices. Herein, a novel manufacturing process was developed to produce smooth channeled polymeric microfluidic devices from rough 3D printed molds. Additionally, we integrated OLIS technology with electroconductive sensors to create high surface area electroactive material with self-cleaning properties, ideal to combat non-specific adhesion of biomolecules.

Point-of-care testing brings diagnosis and treatment monitoring to the site of the patient. It heavily relies on biosensors, which leverage the interactions between a target biomarker and a bioreceptor, to deliver fast and accurate results. However, non-specific binding of molecules and microorganisms on the biointerface can interfere with biomarker-bioreceptor interactions and diminish a biosensor’s sensitivity, specificity, and stability. In turn, this can lead to false diagnoses and ineffective treatments. Omniphobic-lubricant infused (OLI) coatings exhibit slippery, self-cleaning characteristics that repel untargeted molecules and microorganisms to augment the biosensor’s performance. In this work, we investigate the proficiency of OLI coatings in two specific applications: dissolved oxygen sensing and DNA biosensing. First, in water quality monitoring, an OLI coating is applied to the selectively permeable membranes of a dissolved oxygen sensor. Over a three-week incubation period in an environment with accelerated bacterial growth, the coated membranes exhibit a 160% higher reproducibility (10% deviation in sensitivity) and lower biofilm formation (96° static contact angle) in comparison to unmodified membranes (26%, 32°). The second application is in DNA biosensing, where a novel OLI coating uses carbon dioxide plasma activation to embed oligonucleotide probes. It demonstrates an optimized balance of slippery repellency (76° static contact angle, 10° sliding angle) and biosensing functionality, 19% longer clotting times than conventional blocking conditions, and equal sensitivity to PLL-PEG when capturing target DNA in whole blood. Going forward, our research will continue to expand the use of OLI coatings in biosensing applications, particularly exploiting its antibiofouling and anticoagulative capabilities. / Thesis / Master of Applied Science (MASc) / Biosensors are an integral tool in delivering quick and accurate point-of-care diagnosis and treatment monitoring. However, their performance can be impeded by the non-specific binding of undesirable molecules and microorganisms on the sensing surface. Omniphobic lubricant-infused (OLI) coatings have been shown to suppress biofouling and blood clotting on surfaces through exceptional repellency. This thesis focuses on the implementation of OLI coatings in biosensing applications. It investigates the antibiofouling capacity of an OLI coating on a membrane for dissolved oxygen detection. Then, it discusses a novel coating with integrated DNA biosensing functionality for working directly with blood samples. The enclosed work demonstrates that the OLI coating empowers biosensors to deliver more effective point-of-care testing.

Development of repellent surfaces which can supress bacteria adhesion, blood contamination and thrombosis, and non-specific adhesion on diagnostic devices has been a topic of intense research as these characteristics are in high demand. This thesis focused on design and development of omniphobic surfaces based on hierarchical structures and their application for preventing pathogenic contamination and biosensing. First, a flexible hierarchical heat-shrinkable wrap featuring micro and nanostructures, was developed with straightforward scalable methods which can be applied to existing surfaces. These surfaces reduced biofilm formation of World Health Organization-designated priority pathogens as well as minimized risk of spreading contamination from intermediate surfaces. This is due to the broad liquid repellency and the presence of reduced anchor points for bacterial adhesion on the hierarchical surfaces. Next, the developed surfaces were applied to minimize blood contamination and clot formation as well as facile integration of hydrophilic patterns. This led to droplet compartmentalization and was utilized for detection of Interleukin 6 in a rapid dip-based assay. Furthermore, in a review article the need for anti-viral or virus repellent surfaces and future perspectives were discussed as the global COVID-19 pandemic surged and attracted interest toward innovative technologies for suppressing the spread of pathogens. To address the pressing issue of non-specific adhesion in diagnostics devices, an omniphobic liquid infused electrochemical biosensor was developed. This was achieved by electroplating gold nanostructures on fluorosilanized gold electrodes. These electrodes demonstrated rapid and specific detection of Escherichia coli within an hour in complex biological liquids (blood, urine, etc.) without dilutions or amplification steps from clinical patient samples which are major bottle necks when rapid detection systems are sought for at the point of care. / Thesis / Doctor of Philosophy (PhD) / Repellent surfaces have a variety of applications in healthcare, for coating medical devices (e.g. indwelling implants, stethoscopes, and other external devices.), coating hospital surfaces for blood and pathogen repellency, and for developing anti-fouling diagnostic devices. Furthermore, they can be applied in the food sector for limiting contaminations, and in public areas on high-touch surfaces to eliminate the spread of infection. Therefore, there is a need for repellent surface which can be easily applied to surfaces with various form factors while having an easy fabrication method. Featuring hierarchical structures on a heat-shrinkable material, a repellent wrap was designed to be integrated on existing surfaces and repel pathogens and suppress the spread of infection as an intermediate surface. Similar concept was used for designing blood repellent surfaces which were patterned with hydrophilic regions for a rapid dip-based biosensing platform. Finally, surface textures on conductive materials with liquid infused repellent coatings were investigated for electrochemical biosensing in complex biological liquids.

Superhydrophobic and lubricant-infused porous surfaces are two classes of non-wetting surfaces that are inspired by the adaptation of natural surfaces such as lotus leaves, pond skater legs, butterfly wings, and Nepenthes pitcher plant. This dissertation focuses on fabrication and in depth study of bioinspired functional metallic surfaces for applications such as power plant condensers and marine applications. Toward that, first, facile and scalable methods are developed for the fabrication of superhydrophobic surfaces (SHS) and lubricant-infused surfaces (LIS). Second, the corrosion inhibition mechanism of SHS was systematically studied and modeled via electrochemical methods to elucidate the role of superhydrophobicity and other parameters on corrosion inhibition. The anti-corrosion properties of SHS and LIS were systematically studied over a range of temperatures (23°C–90°C) to simulate an actual condenser environment. Moreover, the environment of application often involves using harsh cleaning chemicals. The fabricated non-wetting surfaces were examined over a wide range of acidity and basicity (pH=1 to pH=14). Third, the durability of SHS and LIS is systematically assessed using a set of testing protocols including water impingement tests, scratch wear tests, and accelerated chemical corrosion tests. Considering that industrial environments of application are often turbulent, in addition to static long term corrosion tests, long term dynamic durability was studied in a simulated turbulent condition. Fourth, the performance of the fabricated nonwetting surfaces was systematically studied against calcium sulfate scaling in turbulent conditions and different temperatures. An analytical relationship based on the Hill-Langmuir model is proposed for the prediction of fouling on nonwetting and conventional surfaces alike in dynamic conditions. Overall 1048 individual samples were studied via over 3000 measurements in this dissertation to establish a comprehensive fundamental knowledge base on fabrication and anti fouling characteristics of metallic nonwetting surfaces, which profoundly helps to design appropriate surfaces and fabrication methods based on the use environment. / Doctor of Philosophy / Metallic surfaces such as copper, brass, and aluminum are everywhere in our daily lives. From tumblers, household pipes to the bank of tubes in power plants condensers. Fouling of these surfaces has significant performance and economic impact. Scaling is a type of crystallization fouling like the familiar limescale everyone is familiar to see around the surface of a house kettle. Corrosion is another type of fouling and is detrimental to metallic surfaces. For example, 50% of water consumption in the U.S. is being used in thermo-electric power plants where fouling of metallic surfaces will impede the flow of working fluid, therefore increasing power needed for pumping, decrease efficiency, and decrease ultimate lifetime. One study in 2019 shows corrosion costs 3% of the gross national products of China and it is already known to be similar for other major economies like the USA, which is a hefty cost. Nature has inspired a lot of solutions for mankind. In this work, inspired by natural surfaces such as lotus leaves, butterfly wings, and pond skater legs, a class of superhydrophobic surfaces (SHS) was fabricated. Moreover, a closer look at how the complex human body puts everything in order exposes one of its most striking and essential characteristics: how wet and lubricated its interfaces are. Our lungs, eyes, joints, intestine, bones; either hairy or porous, all are lined wet surfaces that work as fouling inhibitors and defect free surfaces. This also have been observed elsewhere such as on Nepenthes pitcher plant. Inspired by these, another class of non-wetting surfaces, lubricant-infused surfaces (LIS) was fabricated. This dissertation for the first time investigates a rational methodology in the fabrication of metallic SHS and LIS and their anti-scaling and anti-corrosion properties in different environments of application, including a range of temperature (23°Câ€"90°C), various solutions (pH=1 to pH=14), and long-term static and dynamic (turbulent condition) durability. It is believed that this work would profoundly help to identify appropriate nonwetting metallic surfaces based on the intended use environment.