VictorJuiz/thesis huggingface dataset:
Studies of Heterogeneously Catalyzed Liquid-Phase Alcohol Oxidation on Platinum by Sum-frequency Generation Vibrational Spectroscopy and Reaction Rate Measurements

Sum-frequency generation (SFG) vibrational spectroscopy has been used to study the interfacial environment in heterogeneously catalyzed alcohol oxidation on platinum catalysts in the liquid phase. In this work, theoretical concepts relevant to studying the metal liquid interface with non-linear spectroscopy are discussed, and the design of a home-built flow reactor cell with in situ SFG capabilities is described. SFG data is correlated with reaction rate measurements in liquid-phase isopropanol and ethanol oxidation in order to deduce the effect of the surface environment on the catalyst activity and to elucidate the evolution of the surface throughout the course of the reaction. In conditions of aqueous oxidation of ethanol and isopropanol to acetaldehyde and acetone, respectively, SFG results show that water and alcohol competitively populate the first molecular layer. The reaction rate of isopropanol shows an enhancement in the concentration regime where both water and isopropanol are present in the interfacial region. Water is thus implicated in the reaction as a stabilizer of an intermediate or serving as a proton acceptor in a deprotonation step. Similar results are seen for ethanol oxidation, but the role of water appears to be different in ethanol oxidation. Non-resonant SFG is used as a probe for oxygen adsorption on the platinum surface, and it is seen that the surface is covered in oxygen during the oxidation reaction. A kinetic model is proposed where the build-up of oxygen on the catalyst surface is prevented by its reaction with surface hydrogen. A key part of the model is its inclusion of a mechanism for positive feedback through a proposed step involving hydrogen abstraction by an adsorbed oxygen species. A synthetic method for synthesizing nanoparticles of diameter less than 2 nm is reported using platinum ion reduction in the poly(amidoamine) dendrimer induced by ultra violet light irradiation. The new method is inspired by the need for a reduction method other than sodium borohydride, which we show is not effective in reducing platinum, because platinum ions are strongly stabilized by multidentate interaction with the dendrimer amide groups. The interfacial orientation of isopropanol on platinum nanoparticles under conditions of gas and liquid phase catalysis is investigated using SFG based orientational analysis. The SFG results show that the isopropanol adopts a much different configuration on platinum in the liquid phase compared to the gas phase. Finally, the adsorption of amino acids at the polystyrene/H2O and SiO2/H2O interfaces is shown to have significant effect on the orientation and/or concentration of water at both interfaces. The effect of these molecules on water spans the range from highly disordering to highly ordering and depends on the amino acid identity.

Advisor: Somorjai, Gabor A
NEM Relay Scaling for Ultra-low Power Digital Logic

CMOS has been the building block for modern digital logic for decades and the performance and energy efficiency of CMOS continues to improve as technology develops, mainly through scaling. However due to the 60 mV/dec limit on MOS transistors, continue to reduce the power supply voltage would result in an increase in off-stage leakage current that would eventually dominate and increase the energy per operation of a transistor. In order to overcome this barrier, mechanical switches are proposed. Mechanical relays has the benefit of no leakage current through the air gap in the off state, which potentially enables further scaling of power supply voltage that can surpass MOS transistors. Several groups have been able to demonstrate mechanical switches with no leakage and abrupt on-off switching characteristics, however both the sizes of switches (~104 μm2) and the operation voltages (> 10 V) are huge, causing the switching energy to be significantly larger than MOS transistors. Scaling efforts are needed to minimize the switching energy of a mechanical switch./nIn this thesis, prototype relay devices demonstrated by previous studies are discussed and the key factors that need to be addressed in order to minimize the switching energy are pointed out. The minimum switching energy is found to be limited by the contact adhesive force between contacts; studies on prototype devices with different contact areas shows that van der Waals force between contacts are the main source of adhesion in the prototype mechanical relays. Experiments show that by adding surface coating materials with low Hamaker constant can lower the contact adhesive force. In order to lower the structural stiffness, process development of poly-SiGe is optimized through multiple post-deposition processing techniques for reduced stress gradient of 100 nm thin films, a 10X reduction from the prototype devices. The combined learning from adhesive force work and thin film processing leads to the experiments of fabricating scaled devices of 500X smaller footprint. The results show that scaled relays can potentially operate at low voltages (~2V), but more process optimization needs to be done to demonstrate a fully operational device.

Advisor: King Liu, Tsu-Jae
On Jubilee: The Performance of Black Leadership in the Afterlife of Slavery

Using film, television, archival materials, and new media art, this dissertation asks how politically enforced constraints on Black being--especially the origination of racial blackness in slavery and the ongoing availability of Black bodies to gratuitous and structural violence--work through subsequent Black performances of leadership. The philosophical breadth of the concept of "new media" and of the constituent elements of slavery as elaborated by Orlando Patterson invites close study of the ways that human beings can serve as new media. The impulse to create an all-new form of being known as the "Black" allowed a new human labor technology for western Europeans to mediate their libidinal desire and political demands. This dissertation engages the ways this technological paradigm extends into the present.

Advisor: Catanese, Brandi
Relations Among Neighborhood, Parenting, and Effortful Control in Chinese American Children

Although an extensive literature links children's self-regulation abilities with both distal (e.g., neighborhood) and proximal (e.g., parenting) contexts, scarce attention has been paid to identifying potential cultural factors (e.g., ethnic density) in this association. Methodologically, most research has utilized cross-sectional data, with few studies examining the cumulative impact of multiple contexts on children's development and adjustment. Furthermore, it is unknown how these contexts are linked with different self-regulation outcomes among Asian American children. To address these gaps in the literature, I studied 258 first- and second- generation Chinese American immigrant children, using a combination of structured interviews, questionnaire measures, and behavioral tasks completed by children, parents, and teachers. Across two waves of data collection, I investigated the mediated and interactive relations of neighborhood (disadvantage, ethnic density) and parenting style (authoritarian, authoritative) to children's effortful control outcomes. Contrary to expectations, parenting style did not mediate the relation between neighborhood disadvantage and children's effortful control. However, children of families residing in neighborhoods with a higher Asian concentration were more likely to rate their parents as using an authoritarian parenting style, which subsequently predicted lower levels of effortful control. I also found that authoritative parenting for these children had a weaker benefit on their effortful control compared to children residing in less ethnically dense neighborhoods, as rated by their teachers. Taken together, these findings suggest that use of an authoritarian parenting style is more culturally normative in ethnically dense Asian American neighborhoods and may serve as a risk factor for poorer effortful control in this population. Additionally, residing in ethnically dense neighborhoods may confer some risk to Chinese American immigrant children's development of effortful control, regardless of their parents' parenting style. As children reach middle childhood, their perception of their parents' parenting style appears to play a role in determining their self-regulation outcomes, and this extends to both home and school contexts (i.e., both child and teacher reports of effortful control).

Advisor: Zhou, Qing
A Systematic Analysis of Foam Drainage and Stability: Measurements, Mechanisms, and Implications for Anaerobic Digester Foaming

The formation of a substantial foam layer has severe impacts on the overall digestion process that is responsible for the major portion of waste stabilization. An understanding of dynamics of foam produced by three primary causes - dispersed gas bubbles, surface-active materials, and hydrophobic compounds - provides insight into the prevention of the foam layer and into the control of the foam stability. To better understand the mechanisms in three-phase foam dynamics, we developed a systematic methodology to characterize foam drainage behavior using electrical conductance measurements./nWith no sludge conditions, all tested sodium dodecyl sulfate (SDS) foams exhibit a node-dominated drainage regime with high mobility at bubble surfaces. Drainage regime under similar foaming conditions was consistent with existing drainage studies using other measurement techniques in the literature./nThe drainage of sodium dodecylbenzenesulfonate (SDBS) surfactant solution, a commercial form of linear alkylbenzene sulfonate (LAS) that is most frequently found in anaerobic sludge, was studied in detail by several approaches. Two complementary methods of macroscopic drainage investigations (forced and free drainage) were conducted to gain confidence in its validity. The experimental data can be fitted using a power law with an exponent of 1/3 for forced drainage and of 1.0 for free drainage. These data indicate the following drainage behavior: mobile bubble surfaces, causing plug-like flow within Plateau borders, thus dissipation mainly occurs inside the nodes./nWith the drainage studies for a variety of aqueous surfactant solutions, experimental and theoretical studies to include wastewater sludge are important for understanding the stability of three-phase foams, and therefore foaming in anaerobic digesters. The drainage behavior of sludge-containing foams was characterized by our developed method. The presence of anaerobic sludge at total solid (TS) concentrations of approximately 2.5-2.8% induced a transition from the node-dominated regime to a Plateau-border (PB)-dominated regime. This apparent transition was verified in both forced and free drainage experiments. These drainage studies supported a more detailed estimation of foam stability in relation to its structure./nIn summary, our developed method using the electrical conductance measurements was applied to understand the key aspects of foam stability required for prediction and control of foaming in anaerobic digesters. A systematic methodology for assessing foam dynamics was proposed and discussed in two- and three-phase foams.

Advisor: Hermanowicz, Slawomir W
Exploiting Spatial Channel Occupancy Information in WLANs

Current 802.11 networks do not typically achieve the maximum potential throughput despite link adaptation and cross-layer optimization techniques designed to alleviate many causes of packet loss. A primary contributing factor is the difficulty in distinguishing between various causes of packet loss, including collisions caused by high network use, co-channel interference from neighboring networks, and errors due to poor channel conditions./nIn current 802.11 networks, there are two adaptations occurring simultaneously but independently each using packet loss as an indication of a different problem. The first is contention window adaptation, which implicitly assumes all losses are due to collision, and the second is rate adaptation, which implicitly assumes all losses are due to channel errors. Thus, in all high-loss scenarios, at least one of these two adaptations behaves incorrectly, unnecessarily increasing the impact of packet loss./nIn this thesis, we propose a novel method for estimating various collision type probabilities locally at a given node of an 802.11 network. The key to our approach is a signal we call the busy-idle (BI) signal, which is a binary-valued record of the channel occupancy over time as observed locally by a given node. We show that if the access point(AP) periodically broadcasts its BI signal to associated nodes at an overhead of less than 2%, the nodes can use this information in conjunction with locally observable quantities to obtain partial spatial information about the network traffic. With this spatial information, nodes can estimate their probabilities of various types of loss and make adaptations to improve throughput and/or network utility./nWe provide a systematic assessment and definition of the different types of collision, and show how to approximate each of them using local information and the AP's BI signal./nWe verify our methods using NS-2 simulations, as well as using the Ath5k open source wireless card driver in an experimental testbed. We show that our proposed methodology accurately estimates overall collision probability to within 5%. This experimental verification demonstrates the feasibility of our collision probability estimation approach and the resulting throughput gains in practice./nIn addition, we describe a suite of methods which exploit these loss probability estimates and the BI signal to improve network throughput and utility. We show via NS-2 simulations that we can achieve gains of up to 400% via modulation rate adaptation, 350% via contention window adaptation, 25% via packet length adaptation, and 50% via carrier sense threshold adaptation.

Advisor: Zakhor, Avideh
The Nationalization of "Manchuria": Jin Yufu, Manchukuo, and the Dongbei Tongshi

This dissertation focuses on the historian Jin Yufu (1887-1962) to examine the broader transcultural practice of writing ethno-racial histories in twentieth century Northeast Asia. An archaeologist, collector, compiler and historian of Northeast Asian history, a civil official under the Zhang Xueliang regime in Manchuria, and the assistant director of the Fengtian Library under the Manchukuo government (1932-36), Jin was closely tied to an entire network of prominent individuals in political and intellectual circles including eminent Japanese archaeologists and historians of the region. Considering his personal experiences and seminal role in shaping the narrative of Chinese national history, Jin is a key figure in understanding the development of ethnoracial historiography in twentieth century Northeast Asia. I argue that national histories in Northeast Asia developed out of transcultural processes of socio-intellectual interaction. I develop this thesis in two ways. First, I analyze the role of railways in reshaping the regional economy, enabling new forms of mobility and interaction, that simultaneously encouraged the growth of archaeological research and Jin Yufu's participation in a major Japanese excavation of the ancient ruins of the Bohai state capital in present-day Heilongjiang province. Secondly, I place Jin Yufu's classic history of Northeast China, the Dongbei Tongshi (General History of the Northeast), in context with Inaba Iwakichi's seminal 1915 work, Developmental History of Manchuria, and consider how multiple efforts to translate that work into Chinese throughout the 1930s, influenced by Jin's participation and encouragement, culminated in his classic work on Northeast China by 1941.

Advisor: Yeh, Wen-hsin
A Phase-Variable Surface Layer from the Human Gut Commensal Bacteroides

While some microbial encounters can be pathogenic, most interactions between humans and microorganisms do not result in disease. Our gastrointestinal tract harbors approximately 100 trillion organisms, spanning about 1000 species that live in harmony with us. While we provide them with food and shelter, this complex intestinal bacterial community supplies essential nutrients, metabolizes indigestible compounds, protects us from pathogenic organisms and helps develop our immune system, thereby establishing a symbiotic relationship. Bacteroides are one of the most abundant bacterial genera living in the human gut and has long been a model system for studying the molecular mechanisms of commensal-host interactions. In the course of searching for surface structures that have immunomodulatory properties on the host, we serendipitously discovered a previously unknown surface protein BT1927 from Bacteroides that is capable of completely covering the surface of the bacteria by creating a tessellated surface layer. Interestingly, the formation of the entire proteinaceous capsule is controlled by inversion of a single promoter, making it phase-variable. Although only ~ 0.1% of the population produce this capsule in laboratory culture, analyzing the fecal metagenome sequence data from the Human Microbiome Project revealed that ~ 8% of the population produce a homologous capsule in humans, suggesting its significance in vivo. From a series of functional studies, we found that the BT1927-expressing subpopulation is profoundly resistant to complement-mediated killing, due in part to the BT1927-mediated blockade of C3b deposition. Our results show that the Bacteroides capsule is capable of a far greater degree of structural variation than previously known, perhaps to cope with the varying environmental conditions in the human intestine.

Advisor: Riley, Lee W
Fischbach, Michael A
Synthesis and Development of Viral Capsid Templated Light Harvesting Systems

The self-assembling protein shells of viruses have provided convenient scaffolds for the construction of many new materials with well-defined nanoscale architectures. Of these numerous examples, one such application is the use of viral capsids to template synthetic light harvesting structures. Through the combination of modern molecular and chemical biology techniques, the symmetry and self-assembling nature of the viral proteins can be exploited to form regular arrays of chromophores on the protein surface in a site-specific manner. Tobacco Mosaic Virus coat protein (TMVcp) was used to template organic chromophores, forming light harvesting structures reminiscent of biological systems. While many of the processes in photosynthesis are well understood, there is still much mystery surrounding the physical basis for the efficiency seen in natural systems. We set about constructing protein-templated biomimetic light harvesting systems with tunable parameters such as protein attachment chemistry, inter-chromophore distances, and inter-chromophore geometries. Through genetic manipulation of the TMVcp, protein mutants were produced with various sites of reactivity on the monomeric protein surface, manifesting as regularly spaced arrays within the assembled capsid. The spatial and geometric relationships of the reactive sites were investigated, along with the resulting protein assembly state. Next, chromophores were introduced at various locations and investigated structurally and spectroscopically. The spectral signatures observed with a range of chromophores, geometries, and pigment-protein attachments were compiled for numerous TMVcp-templated systems, and the effects of protein-templating discussed. The overall goal of this work is to gain insight into the origin of the spectral and energetic effects behind the efficiencies observed in natural systems through the use of highly tunable synthetic biomimetic systems. For a truly biomimetic system to be produced, however, there must be a charge-separation event involved in the light harvesting process. We then turned our efforts to the synthesis of water-soluble phthalocyanines capable of protein attachment. Phthalocyanines are a near infrared absorbing class of chromophores, important for their sensitization properties, and of particular interest to us for their use as singlet oxygen generation materials in photodynamic cancer therapy. The synthesis of both symmetric and asymmetric phthalocyanines was accomplished, followed by characterization. Finally, an asymmetric phthalocyanine was integrated into the interior of the bacteriophage MS2 viral capsid, and its ability to generate singlet oxygen was investigated.

Advisor: Francis, Matthew B
The Roles of Sox2 in Stem and Progenitor Cells of the Mammalian Olfactory Epithelium

Olfactory neurogenesis is essential in certain mammals, as they are dependent on the detection of odors to guide social behaviors, localize food, find mating partners, and avoid predators. The mammalian olfactory epithelium (OE) supports adult neurogenesis. Under homeostatic conditions, multipotent stem/progenitor cells, the globose basal cells (GBCs), contribute to neurogenesis to replace the constant turnover of sensory neurons in the neuroepithelium. The constant turnover of neurons at homeostasis means that a stem/progenitor cell population must be present to sustain neurogenesis throughout the life of the organism. Stem/progenitor cells must self-renew so that they are not exhausted during neurogenesis. Additionally, the adult OE has tremendous capacity for tissue regeneration following injury, making it an ideal model for the study of stem/progenitor cell regulation and neurogenesis. Following injury, the OE activates the quiescent, multipotent horizontal basal cells (HBCs), causing them to proliferate and differentiate into all of the cellular constituents of the OE. The Sox2 transcription factor is expressed in both HBCs and GBCs, and is a characteristic of stem cells in many tissues, including neurogenic niches of the of the central nervous system (CNS), namely the SVZ and SGZ. Sox2 has been identified as a key component in self-renewal and multipotency of NSCs (Ferri et al., 2004; Ellis et al., 2004; Pevny and Nicolis, 2010). Sox2 loss of function in NSCs of the CNS results in impairments in proliferation, loss of NSCs and neuronal progenitors, followed by a complete loss of neurogenesis, in both the embryonic and adult mouse brains (Ferri et al., 2004; Miyagi et al., 2008; Favaro et al., 2009). In the adult OE, Sox2 is expressed in HBCs, GBCs, and Sus cells. However, the functions of Sox2 in self-renewal and differentiation of HBCs and GBCs have remained largely unknown. To resolve the differences that underlie Sox2 function in HBC and GBC self-renewal, proliferation, and differentiation, targeted Sox2 ablation in transgenic mouse models were employed. Combined with lineage-tracing, fate mapping, pulse-labeling, and immunohistochemistry, the following was determined: (1) Sox2 is dispensable for HBC maintenance and their faithful self-renewal following injury. (2) HBCs require Sox2 to generate proliferative, self-renewing GBCs and neurons. (3) Sox2 is indispensable for steady-state maintenance of long-term, self renewing GBCs and neurogenesis. These findings not only underscore the necessity for Sox2 in maintaining an active progenitor pool that contributes to long-term neurogenesis, but highlight the functional differences Sox2 exerts on the HBCs and GBCs.

Advisor: Ngai, John