Search results

Title: ISOLATION OF TRANSPOSON MEDIATED TRANSGLUTAMINASE MUTANTS OF DROSOPHILA MELANOGASTER
Creator: Yang, Hua
Date: 2016, 2016-05
Description: Transglutaminase, Tg, catalyzes the formation of isopeptide bonds crosslinking and stabilizing protein complexes. The best-known factor XIII...
Show moreTransglutaminase, Tg, catalyzes the formation of isopeptide bonds crosslinking and stabilizing protein complexes. The best-known factor XIII crosslinks fibrin in clots. Paradoxically, there is an unexpected and counterintuitive correlation between factor XIII levels and heart attack mortality. Since factor XIII strengthens fibrin and resists fibrinolysis, higher XIII activity would be expected to lead to more stable fibrin clots and so more fatal atherosclerotic plaques; but it actually results in reduced mortality. One hypothesis to explain this is that Tg activity may also stabilize cardiac muscle tissue. Studies have shown that Tg is expressed in human embryonic myoblasts. Therefore, we suggest that muscular attachments may be strengthened by Tg, and play a vital unrecognized role in the muscular attachment. Humans have 9 Tg genes, complicating studies. However Drosophila melanogaster, D.m., has only one Tg gene, and is an attractive model system. We isolated 39 mutant D.m. lines gene produced by transposon mobilization in locus in a "dirty" fashion expected to create random deletions within the Tg locus. We then characterized them by PCR and sequencing, as well as functional assays, in an attempt to develop a Tg null line to test this hypothesis. The aim is to identify a line with all of Tg removed, but with neighboring genes unperturbed. Once the approximate break points were identified by PCR, we did DNA sequencing to fully characterize the genomic breakpoint. According to the DNA sequencing results, one line is specific for Tg exon1, and eliminates one of the two known Tg transcripts. Another line eliminated almost the entire catalytic domain. We also did RT-qPCR for two lines that were sequenced to determine their genomic characteristics. Both of these lines are viable but with subtle developmental defects, showing that Tg deficiency is not lethal in D.m.
M.S. in Biology, May 2016
Show less

Title: MONITORING, MODELING, AND TREATMENT OF ODORS/ODORANTS AT WATER RECLAMATION PLANTS
Creator: Zhang, Yanming
Date: 2012-04-23, 2012-05
Description: A thorough study including odor monitoring, modeling and treatment as three important aspects of odor control in WRPs has been performed in...
Show moreA thorough study including odor monitoring, modeling and treatment as three important aspects of odor control in WRPs has been performed in this research. Measurement of H2S emissions from odor sources was proven to be an essential step in odor monitoring program. The H2S emission rates were measured from various sources throughout a WRP for 9 sampling events during winter and summer. During summer, both the average and the maximum emission rates of H2S from liquid treatment processes increased significantly compared to those measured during winter. However, for solids-handling processes, the emission rates remained constant because sludge characteristics did not vary throughout the year. The total sulfide concentrations present in liquid treatment processes were higher than those in preliminary and primary treatment units but at much lower levels in secondary treatment. Rates of H2S emission from the headworks were correlated to daily average wastewater temperature, TKN concentration, and flow rate. AERMOD was used as the modeling tool to evaluate the odor impact of Egan WRP on the surrounding communities. The emission rates could significantly affect the modeling results. Long-term H2S monitoring increases the possibility of developing the proper emission rate for the worst-case scenario. Excluding the modeling during the night would avoid overestimation of odor impact and excessive odor control. In the laboratory-scale study of O3 oxidation of H2S, O3 oxidation was proven to be a fast and effective method to remove H2S from the odorous air emitted from wastewater treatment processes. The increased initial ratio of O3/H2S enhances the removal rate of H2S. The consumption ratio of O3/H2S is a function of input reactant ratios. A multiple linear regression model (R2=0.84) has been developed to predict the H2S residual for given initial H2S and O3 concentrations and reaction time. The increased moisture content of the odorous air enhanced the H2S removal while DMS and DMDS inhibit H2S removal by competing for the limited O3 supply.
Ph.D. in Environmental Engineering, May 2012
Show less

Title: THERMODYNAMIC PROPERTIES AND PHASE EQUILIBRIA OF SELECTED HEUSLER COMPOUNDS
Creator: Yin, Ming
Date: 2015, 2015-12
Description: Heusler compounds are ternary intermetallics with many promising properties such as spin polarization and magnetic shape memory effect. A...
Show moreHeusler compounds are ternary intermetallics with many promising properties such as spin polarization and magnetic shape memory effect. A better understanding of their thermodynamic properties facilitates future design and development. Therefore, standard enthalpies of formation and heat capacities from room temperature to 1500 K of selected Heusler compounds X2YZ (X = Co, Fe, Ni, Pd, Rh, Ru; Y = Co, Cu, Fe, Hf, Mn, Ni, Ti, V, Zr; Z = Al, Ga, In, Si, Ge, Sn) and half-Heusler compounds XYSn (X = Au, Co, Fe, Ir, Ni, Pd, Pt, Rh; Y = Hf, Mn, Ti, Zr) were measured using high temperature direct reaction calorimetry. The measured standard enthalpies of formation were compared with those predicted from ab initio calculations and the extended semiempirical Miedema's model. Trends in standard enthalpy of formation with respect to the periodic classification of elements were discussed. The effect of a fourth element (Co, Cu, Fe, Pd; Ti, V; Al, Ga, In, Si, Ge) on the standard enthalpy of formation of Ni2MnSn was also investigated. Lattice parameters of the compounds with an L21 structure were determined using X-ray powder diffraction analysis. Differential scanning calorimetry was used to determine melting points and phase transformation temperatures. Phase relationships were investigated using scanning electron microscopy with an energy dispersive spectrometer. The isothermal section of the Fe-Sn-Ti ternary system at 873 K was established using equilibrated alloys. Three ternary compounds including the Heusler compound Fe2SnTi were observed. A new ternary compound Fe5Sn9Ti6 was reported and the crystal structure of FeSnTi2 was determined for the first time.
Ph.D. in Mechanical, Materials and Aerospace Engineering
Show less

Title: INVESTIGATION OF ANION EXCHANGE MEMBRANES FOR ELECTROCHEMICAL ENERGY CONVERSION AND STORAGE SYSTEMS
Creator: Wang, Lihui
Date: 2017, 2017-05
Description: The alkaline stability of poly (arylene ether) backbones in anion exchange membranes (AEMs) derivatized with quaternary benzyl N, N-...
Show moreThe alkaline stability of poly (arylene ether) backbones in anion exchange membranes (AEMs) derivatized with quaternary benzyl N, N- dimethylhexylammmonium (DMH+) and trimethylammonium (TMA+) cation groups were investigated in poly (2,6- dimethyl 1,4-phenylene) oxide (PPO) and Udel® polysulfone (PSF) polymers. Previous studies have demonstrated that quaternary ammonium and phosphonium groups trigger backbone degradation in commercially available poly (arylene ether)-based AEMs, despite the base polymers’ resilience to alkaline solutions. Herein, I demonstrate that the electron withdrawing or donating character in the poly (arylene ether) backbone ultimately dictates whether the prepared AEMs will become brittle in alkaline media due to cation-triggered backbone degradation (Arges, Parrondo, Johnson, Nadhan, & Ramani, 2012a; Christopher G. Arges, Lihui Wang, Javier Parrondo, & Vijay Ramani, 2013). Mitigation of cation-triggered backbone degradation was only achieved when electron withdrawing substituents (not including the cation), such as sulfone or bromine, were eliminated from the polymer backbone (or, alternately, when electron donating groups were present). Hence, PPO AEMs prepared through chloromethylation, rather than free radical bromination, were resistant to backbone hydrolysis in alkaline media because each cation-functionalized repeat unit had two electron-donating methyl groups rather than a single methyl group. This study presents some design rules for preparing mechanically stable poly (arylene ether) AEMs from low cost, commercially available polymers for alkaline electrochemical devices.
Ph.D. in Chemical Engineering, May 2017
Show less

Title: EFFECT OF REACTANT CONCENTRATIONS AND AGING EFFECT IN THE SYNTHESIS OF SILVER NANORODS
Creator: Wang, Guan
Date: 2016, 2016-05
Description: In the recent years, anisotropic metallic nanoparticles have drawn much attention because of their unique optical properties. Particularly,...
Show moreIn the recent years, anisotropic metallic nanoparticles have drawn much attention because of their unique optical properties. Particularly, gold and silver nanorods show great potential in extensive applications such as health care, food storage, drug delivery, biosensor, and cancer treatment. Among a variety of nanorods synthesis methods, the seed-mediated growth approach stands out due to its mild and convenient experimental conditions. However, there exist two defects of this method, the poor reproducibility and low yield of nanorods. In order to create nanoparticle systems of reproducible quality in high yields, a deeper understanding of the mechanism of nanorods formation as well as identifying the more important variables is necessary. In this study, the original seed-mediated growth method has been modified to promote the reproducibility and yield of nanorods. Effects of CTAB concentration and ages of growth solution have been investigated in the nanorods formation process. The results suggest that a high concentration of CTAB is not necessary for the growth process and the age of growth solution can affect the optical performance of nanorods. In a brief survey on the stability property of nanorods, it shows that the degradation rate decreases with increasing concentrations of CTAB.
M.S. in Chemical Engineering, May 2016
Show less

Title: EFFECT OF TEMPERATURE, MOISTURE CONTENT AND SOIL SURFACE AREA ON THE BIOLOGICAL DEGRADATION OF BIOSOLIDS ADDED TO SOIL
Creator: Wen, Dongqi
Date: 2016, 2016-05
Description: The objective is to develop and apply an organic matter degradation model (OMDM) that predicts changes in the biological degradation of...
Show moreThe objective is to develop and apply an organic matter degradation model (OMDM) that predicts changes in the biological degradation of organic matter added to soils as a function of soil temperature, moisture content and mineral surface area using data from field and laboratory measurements. A one year long laboratory study was conducted to determine biosolids microbial degradation rates (21 ˚C and 20% moisture content) for soils from eight different fields Biosolids microbial degradation rates were also determined for the eight soils under field condition (10 ˚C and 10% moisture content) by applying a degradation rate model (DRM). The total mineral surface areas for 27 soil samples were also determined. Regression analysis revealed that the degradation rate was positively associated with mineral soil surface area (R2=0.85) and that the biosolids application rate is not significantly associated with the biosolids degradation rate (p value =0.35>0.01). The OMDM determines a decomposition rate of 1.04 yr-1 at 30 ˚C, 20% moisture content, and 10 m2/g soil and provides correction factors for changes in soil temperature, moisture, and mineral surface area. The model predicted in changes of the biological degradation rate of biosolids added to soils with mineral surface areas that vary from 1 to 10 m2/g soil under laboratory and field conditions. A comparison of the measured and simulated degradation rates for eight different soils produced R2 = 0.87 for field data. The model was also able to predict the degradation rate of biosolids for 19 additional soils under field conditions (R2=0.89). The model was also applied to agricultural plant litter. The estimated degradation rates are 0.45 yr-1 corn stover, 0.35 yr-1 oats, 0.26 yr-1 wheat, and 0.13 yr-1 millet at 30 ˚C, 20% moisture content and 10 m2/g. This study demonstrates that the effects of environmental conditions and soil mineral surface area have a significant impact on degradation rates of organic matter and must be considered when assessing degradation rates for organic matter added to soil. Higher temperatures and moisture content and finer soils are related to larger degradation rates.
Ph.D. in Environmental Engineering, May 2016
Show less

Title: RE-IMAGING ANTIQUITIES IN LINCOLN PARK: DIGITIZED PUBLIC MUSEOLOGICAL INTERACTIONS IN A POST-COLONIAL WORLD
Creator: Whittaker, Daniel Joseph
Date: 2015, 2015-12
Description: The study of an architecture of autonomy consists of theoretical investigations into the realm of building types where a sole use or purpose...
Show moreThe study of an architecture of autonomy consists of theoretical investigations into the realm of building types where a sole use or purpose is manifest in a structure that could, site provided, be constructed. However, provisions that conventional architecture traditionally provide are not present in these explorations. Technological advancements such as indoor plumbing, electric lights, and vertical conveyance systems in the form of elevators and escalators are excluded. Platonic geometric form-making are instead thoroughly investigated, imagined, and manipulated for the purposes of creating new spatial experiences. The desired resultant is an architecture of singularity, an architecture of fantastical projection. Through a series of two theoretical ritual-based investigations, three-dimensional form manipulation and construction of proportioned scale models, the essence of elements that compose a spatial experience contributed to a collection of metaphorical tools by which the designer may use to build a third imagined reality: the re-imagination of the archetypal museum. A building whose purpose is not solely to house ancient objects in a near hermetically-sealed environment, free of temperature, humidity and ultra-violet light aberrations, but is a re-imagined. A structure meant to engage the presence of two seemingly divergent communities: the local patron/visitor and the extreme distant denizen. This paper also examines key contemporary global artists’ work and their contributions to the fragmentation / demolition of architectural assemblages for thepurposes of re-evaluating the familiar vernacular urban landscape while criticallypositioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.positioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.positioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.positioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.positioning the rôle of both the artifact and gallery in shaping contemporary audience’s museum experiences. The power of the internet and live-camera broadcasting of images utilizing both digital image recording and full-scale screen-projections enable the exploration of “transporter-type” virtual-reality experiences: the ability to inhabit an art work’s presumed original in situ location, while remaining in Chicago as a visitor within a vernacular multi-tenant masonry structure: vacated, evicted, and deconstructed for the purposes of displaying art amidst a new urbane ruin. The complexities of this layered experience is meant to simultaneously displace and interrupt a typical set of so-called a priori gallery expectations while providing the expectant simulacrum that video cameras and screens provide, whetting a contemporary patron’s appetite.
M.S. in Architecture, December 2015
Show less

Title: HOUSING CHINESE DREAMS
Creator: Wong, Jing Jie
Date: 2017, 2017-07
Description: The Chinese Dream is President Xi Jinping's integrative and transformative vision for China, with the goals to achieve "a great rejuvenation...
Show moreThe Chinese Dream is President Xi Jinping's integrative and transformative vision for China, with the goals to achieve "a great rejuvenation of the Chinese nation". However, the realities in China seem to be far from the conditions of a dream. The emerging Chinese middle class are eager to join the army of slaves to their impossible mortgages for their bedroom town homes, in fulfillment of what the modern Chinese psychodynamics have collectively decided to be a necessity in pursuance of a good life. So, where are the capacities of the Chinese Dream for the individuals in this modern times? The dream has to address the deteriorating sense of belonging and home of the millions of working middle class, before it can even consider itself a collective effort. The individuals should be encouraged to dream and strive, in order for this to happen, the fundamentals of a good living environment must be collectively accessible. Studies on the collective forms of housing in China's recent history had shed light onto the importance of urban elements such as the hutong network and socialist work unit in social control. However, a case study on China's gated housing models had also opened up discussions on what a complete razing of culture, history and forced resettlements had done in the name of providing quantities of housing within China's neoliberal shift. This thesis explores the elements of providing quality living environments for this group of people that have been called upward-mobile, tech-savvy and entrepreneurial. With the idea of owning a house becoming increasingly important to the Chinese middle class, architecture attempts to bridge gaps between the realities of the sub-par housing towers in gated peripheral areas and the dying traditions of collectivism. By looking at the success of the hutong and danwei dormitories as spaces for social order as well as spaces for commercial and social interaction, a translation of this is deemed to be emulated in modern housing. A super-hybrid of dwellings and designed "programmatic infection" is bound to happen by studying the development of "dream-like" housing prototypes in history.
M.S. in Architecture, July 2017
Show less

Title: Parking Demand Forecasting Using Asymmetric Discrete Choice Models with Applications
Creator: Zhang, Ji
Date: 2023
Description: Using discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The...
Show moreUsing discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The most used discrete choice models have fairly simple mathematical expressions, such as the probit and logit models. The application of simple models helps release the computational burdens brought by parameter estimation tasks in practice, but the cost is the unwanted properties of classic models such as the “symmetry property” that we argue is often undesirable in many fields. To some extent, the symmetry property of related models limits the shape of curves that makes the model fitting less flexible technically. This study addresses the following question: “Can discrete choice models with asymmetry property outperform classic models with symmetry property in forecasting travelers’ parking location choices?” The contributions of this study include: (1) providing a new perspective of using asymmetric discrete choice models to explain and forecast individual’s parking location choice; and (2) completing the travel demand forecasting process from choices of the destination zone centroid to the parking location, enabling parking choice forecasting. This provides a generalized framework to calibrate and validate asymmetric discrete choice models with the field observed parking facility-specific arrival profile data integrated into a large-scale, high-fidelity regional travel demand model. Further, an experimental study is conducted to compare the performance of the proposed asymmetric discrete choice models in the parking demand forecasting framework. The results suggest that asymmetric discrete choice models for individual’s parking choice modeling outperform the symmetric discrete choice models such as the logit models owing largely to their flexibility of parameter fitting and training using the available dataset.
Show less

Title: Estimation of Platinum Oxide Degradation in Proton Exchange Membrane Fuel Cells
Creator: Ahmed, Niyaz Afnan
Date: 2024
Description: The performance and durability of Proton Exchange Membrane Fuel Cells (PEMFCs) can be significantly hampered due to the degradation of the...
Show moreThe performance and durability of Proton Exchange Membrane Fuel Cells (PEMFCs) can be significantly hampered due to the degradation of the platinum catalyst. The production of platinum oxide is a major cause of the degradation of the fuel cell system, negatively affecting its performance and durability. In order to predict and prevent this degradation, this research examines a novel method to estimate degradation due to platinum oxide formation and predict the level of platinum oxide coverage over time. Mechanisms of platinum oxide formation are outlined and two methods are compared for platinum oxide estimation. Linear regression and two Artificial Neural Network (ANN) models, including a Recurrent Neural Network (RNN) and Feed-forward Back Propagation Neural Network (FFBPNN), are compared for estimation. The estimation model takes into account the influence of cell temperature and relative humidity.Evaluation of relative errors (RE) and root mean square error (RMSE) illustrates the superior performance of RNN in contrast to GT-Suite and FFBPNN. However, both RNN and GT-Suite showcase an average error rate below 5% while the FFBPNN had a higher error rate of approximately 7%. The RMSE of RNN shows mostly less compared to FFBPNN and GT-Suite, however, at 50% training data, GT-Suite shows lowest RMSE. These findings indicate that GT-Suite can be a valuable tool for estimating platinum oxide in fuel cells with a relatively low RE, but the RNN model may be more suitable for real-time estimation of platinum oxide degradation in PEM fuel cells, due to its accurate predictions and shorter computational time. This comprehensive approach provides crucial insights for optimizing fuel cell efficiency and implementing effective maintenance strategies.
Show less

Title: Parking Demand Forecasting Using Asymmetric Discrete Choice Models with Applications
Creator: Zhang, Ji
Date: 2023
Description: Using discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The...
Show moreUsing discrete choice models to forecast travelers parking location choice has been a branch of parking demand research for many years. The most used discrete choice models have fairly simple mathematical expressions, such as the probit and logit models. The application of simple models helps release the computational burdens brought by parameter estimation tasks in practice, but the cost is the unwanted properties of classic models such as the “symmetry property” that we argue is often undesirable in many fields. To some extent, the symmetry property of related models limits the shape of curves that makes the model fitting less flexible technically. This study addresses the following question: “Can discrete choice models with asymmetry property outperform classic models with symmetry property in forecasting travelers’ parking location choices?” The contributions of this study include: (1) providing a new perspective of using asymmetric discrete choice models to explain and forecast individual’s parking location choice; and (2) completing the travel demand forecasting process from choices of the destination zone centroid to the parking location, enabling parking choice forecasting. This provides a generalized framework to calibrate and validate asymmetric discrete choice models with the field observed parking facility-specific arrival profile data integrated into a large-scale, high-fidelity regional travel demand model. Further, an experimental study is conducted to compare the performance of the proposed asymmetric discrete choice models in the parking demand forecasting framework. The results suggest that asymmetric discrete choice models for individual’s parking choice modeling outperform the symmetric discrete choice models such as the logit models owing largely to their flexibility of parameter fitting and training using the available dataset.
Show less

Title: Estimation of kinetic parameters of the Coronavirus main protease by Bayesian regression and utility for drug design
Creator: La, Van Ngoc Thuy
Date: 2024
Description: The main protease (MPro) plays a crucial role in the Coronavirus life cycle and is a target for newly developed antivirals against SARS-CoV-2....
Show moreThe main protease (MPro) plays a crucial role in the Coronavirus life cycle and is a target for newly developed antivirals against SARS-CoV-2. MPro is conserved across various members of the coronavirus family. The enzyme of SARS-CoV-2 and other members of the coronavirus family share similar structures and functions, commonly existing as obligate dimers. However, MPro from MERS-CoV exhibits weaker dimerization and often exists as a monomer under biochemical assay conditions, which may not accurately reflect the conditions relevant to antiviral therapy in infected cells.Interestingly, because ligand binding increases dimerization, the addition of ligands has been reported to enhance MPro activity at low concentrations before reducing it at higher concentrations. This phenomenon, known as ligand-induced dimerization, was observed not only in biochemical assays of MERS-CoV MPro but also of SARS-CoV-2 mutated MPro with weakened dimerization. Unfortunately, there are currently no published biochemical models that quantitatively fit these non-monotonic concentration-response curves. This poses a significant challenge in estimating IC50 from these curves, which is an important metric for drug potency and commonly used in drug screening. As a result, predicting compound behavior in cellular models becomes challenging.To address this challenge, we developed an enzyme kinetic model that integrates dimerization and ligand binding. We utilized Bayesian regression for the model to fit datasets published in the aforementioned study of SARS-CoV-2 MPro. Subsequently, we adjusted the model to achieve a global fit for multiple datasets of MERS-CoV MPro and estimate IC50 values. Finally, we examined the correlation between estimated IC50 and cellular EC50, demonstrating that our model is capable of predicting cellular EC50 for the biphasic curves observed in MERS-CoV MPro.
Show less

Title: Selective Interface Reaction Studies during Atomic Layer Deposition Process Based on Surface Properties of Metal Oxide Substrate and Chemical Properties of Precursors
Creator: Luo, Chunxin
Date: 2024
Description: Site-selective atomic layer deposition (SS-ALD) on metal oxide nanoparticles will require subtle surface chemical control through site...
Show moreSite-selective atomic layer deposition (SS-ALD) on metal oxide nanoparticles will require subtle surface chemical control through site-specific surface functionalization (e.g. selective hydration) or highly discriminating reactivity. Two main factors, including the properties of substrate and proton-affinity of the precursors, which would affect the selectivity of ALD process will be discussed and the mechanism will be revealed in this thesis.The adsorption step on substrate surface of the metal precursors will affect the first half reaction of ALD process. Our hypothesis here is that surface hydroxyl group on different oriented metal oxide surface have different desorption temperature points. In this case, we can control the adsorption step by simply adjusting substrate temperature to targeting temperature point where it allows us to achieve selectively removal of the targeting hydroxyl groups while leaving the hydroxyl remain on desired site. Selectively dihydroxylation on In2O3 (111) and (211) single crystal surface is studied, and further SS-ALD is achieved on high-oriented In2O3 (111) thin-film by simply thermal treatment, which indicated that discriminant dihydroxylation can be a promising pathway to SS-ALD. Thermal dehydration of facet-specific anatase TiO2 truncated-octahedron, disks, and rods samples is investigated by Fourier-transform infrared spectroscopy (FTIR). Potential facet-specific reaction window was revealed. However, the various oxidation state on transition metal created more complicated surface atomic arrangement, which make the study of thermal dihydroxylation on nanoparticles even more complicated. Thus, we turn our focus back on the In2O3 material. Well-constructed and facet specific In2O3 nanoparticle cube, octahedron and trapezohedron with only one of (100), (111), and (211) surface exposed, respectively, were synthesized and investigated by DRIFT. Further ALD treated In2O3 nanoparticles were studied. Moreover, epitaxial growth of In2O3 on YSZ (100) and (111) substrates were obtained by thermal ALD method. Post-annealing treatments applied on these epitaxial growth In2O3 samples. The relationship between the grow orientation of single crystal surface and electrical performance are investigated and discussed. Finally, some preliminary studies of the relationship between the ligand-dependent precursor and ALD performance were conducted by using the in-situ FTIR method. Surface reaction mechanisms during the ALD process with porous AAOAl film as substrate were studied. Selectivity exhibited from DMAI precursor was investigated and discussed. ALD performance and related surface reaction of Ga precursor such as Ga2(NMe2)6, Ga(amd)(NMe2)2, and Ga(amd)3 were studied by in-situ FTIR as well. Overall, thermal evolution of surface hydroxyl group on faceted TiO2, In2O3 nanoparticles were probed by temperature variable FTIR. Selective proton-dependent chemical reaction can be achieved on different oriented metal oxide surface. Orientation dependent electrical properties was studied on high-oriented In2O3 (111) and In2O3 (100) surface. An alternative way of in-situ FTIR measurement to study the surface reaction during ALD process was designed and investigated. Despite the remaining work, the concept and methodology of site-selective atomic layer deposition (SS-ALD) and associated probing techniques have the potential to captivate researchers in the fields of surface chemistry, semiconductors, and electrical devices.
Show less

Title: Assessing the Impact of Understanding Nature of Scientific Knowledge and Understanding Nature of Scientific Inquiry on Learning about Evolution in High School Students
Creator: Jimenez Pavez, Juan Paulo
Date: 2022
Description: Nature of Scientific Knowledge (NOSK) and Nature of Scientific Inquiry (NOSI) are important components of scientific literacy and important...
Show moreNature of Scientific Knowledge (NOSK) and Nature of Scientific Inquiry (NOSI) are important components of scientific literacy and important educational objectives in science education. Recent literature theorizes that understanding both NOSK and NOSI increases students' understanding of science content knowledge. However, this assumption has yet to be tested empirically. Much research has been done on developing informed views of NOSK and NOSI for students in kindergarten through twelfth grade, but research on the effect of understanding NOSK and NOSI on facilitating science learning in high school appears limited.The main purpose of this study was to empirically test the assumption that understanding NOSK and NOSI improves science student content learning, in particular learning about evolution. This study also aimed to determine which NOSK and NOSI aspects are most useful in such an endeavor. Using a quasi-experimental, nonequivalent control group design, a sample of 453 9th grade high school students from 12 classes in a large Chilean city were randomly assigned to intervention and control groups via classroom clusters (Intervention groups = 6, Control groups = 6). Students in the intervention groups were given a special online explicit and reflective five-week NOSK/NOSI Unit, followed by an online five-week Evolution Content Unit, as a treatment. Those in the control groups received only the online five-week Evolution Content Unit. To measure understanding of NOSK, understanding of NOSI, and understanding about evolution, students answered three valid and reliable instruments: The Views of Nature of Science (VNOS D+), the Views about Scientific Inquiry (VASI), and a multiple-choice Evolution Content Test. The students' answers to the VNOS D+ and VASI questionnaires were scored as naive, mixed, or informed according to the level of understanding for each aspect, and the answers to the evolution content test were scored as correct or incorrect. The results of this study showed that the NOSK/NOSI Unit was effective in improving understanding of NOSK and NOSI aspects in the intervention groups. The results also showed that the Evolution Content Unit was effective in improving understanding about evolution in both groups. However, students in the intervention groups outperformed their peers in the control groups by scoring higher on the Evolution Content Test. Further analysis revealed that students with informed views of NOSK and NOSI achieved better scores on the Evolution Content Test than students with naive views, supporting the argument that understanding NOSK and NOSI facilitates learning about evolution. In addition, all aspects except for the difference between Theories and Laws (NOSK) had a significant positive impact on learning about evolution. Taken together, the findings of this dissertation support the assumption that understanding NOSK and NOSI improves learning about evolution. Furthermore, most NOSK and NOSI aspects seem to foster understanding about evolution. These are new insights, especially about the importance of understanding NOSI for learning about evolution. Some limitations for this study include the remote context in which the study took place and the potential bias in the qualitative analysis of the VNOS D+ and VASI questionnaires.
Show less

Title: ELECTROACTIVE COLLOIDAL MATERIALS DERIVED FROM POLYOXOMETALTES
Creator: Swenson, Lasalle
Date: 2018, 2018-05
Description: Polyoxometalates (POMs) are transition metal-oxide clusters formed by the early transition metals V, Mo, and W. As a subclass of metal oxides,...
Show morePolyoxometalates (POMs) are transition metal-oxide clusters formed by the early transition metals V, Mo, and W. As a subclass of metal oxides, POMs have a number of prototypical physical and chemical properties: solubility; thermal and solvent stability; Brønsted acidity; chemical and photochemical redox activity; photo- and electrochromism; and magnetic properties. POMs have been applied to a variety of technical areas, including catalysis, photocatalysis, biomedicine, and magnetism. As discreet molecular units having well-defined chemical properties, POMs are attractive building blocks for new materials whose properties could be rationalized in terms of their constituents at the molecular level. Towards that end, we have synthesized and characterized a series of new extended structure materials containing the organofunctionalized polyoxocationic species, [NaVIV 6O6{(OCH2CH2)2N(CH2CH2OH)}6]+ (NaV6 +). Three of the new materials are classified as POM ionic crystals and contain NaV6 + and Keggin polyoxoanions [(PW12O40)3-, (SiW12O40)4- or (SiMo12O40)4-] as molecular constituents: [NaVIV 6O6{(OCH2CH2)2N(CH2CH2OH)}6]3(PW12O40)·12H2O G1, [NaVIV 6O6{(OCH2CH2)2N(CH2CH2OH)}6]4(SiW12O40)·20H2O G2, and [NaVIV 6O6{(OCH2CH2)2N(CH2CH2OH)}6]3(HSiMo12O40)·13H2O G3. The final two materials (hereafter C1 and C2) are obtained as redistributable colloids derived from NaV6 + and the mixed-addenda Keggin structure polyoxoanion (PVW11O40)4- (VW11 4-). C1 contains the single polyoxocation constituent NaV6 +, while C2 contains both NaV6 + and VW11 4-. We have characterized the materials using PXRD, FTIR and UV-vis spectroscopy, TGA, SEM/EDX, elemental analysis, and cyclic voltammetry. G1, G2, and G3 are nanocrystalline and composite in nature, containing intact oxometallic cores of their respective polyoxoanion and polyoxocation building block units. Intercluster Coulombic interactions are the driving force of composite formation. These are the first materials derived from Coulombic interactions of polyoxoanions with covalently organo-functionalized polyoxocations. Cl and C2 are colloidal in nature and obtained in the form of micrometer-scale monoliths. They are the first POM-derived colloidal materials that are readily synthesized, isolated, and redistributed in practical quantities. The monoliths are insoluble in a variety of organic media including lower aliphatic alcohols. They readily form thin-films (δ < 100 um) by solvent casting. Owing to their extended nature, redistributable and isolable properties, the materials C1 and C2 may considered a new form of POM heterogenation. We use cyclic voltammetry (CV) to show that the constituents of the new materials are electrochemically addressable; a finding which opens the door to possible applications in sensing, energy storage and (electro-)chemical catalysis. With an eye towards technological applications, we demonstrate the systematic deposition of C2 onto indium tin oxide (ITO) using electrophoretic deposition, and show (CV) that we can access the electrochemical redox centers of its constituents following deposition. These materials demonstrate the activity of NaV6 + as a soft-chemical constituent partner to similar scale POM counter-anions, suggesting further synthetic investigations using this unique species. Owing to the redox properties of their constituents, the new materials present hybrid surfaces that may be considered intriguing prospective (multifunctional) heterogeneous oxidation catalysts. The electroactive nature of the materials also suggests prospective applications in energy storage and conversion, for example, as the active components of ion-insertion type capacitors and batteries. Electrocatalysis and sensing are also prospective application areas. The extended, as opposed to molecular, structure of the materials, suggests possible advantages when forming polymeric composites with conducting and nonconducting polymers, such as: an increased resistance to leeching, the emergence of favourable polymeric film mechanical properties, and the emergence of favorable electron and counterion tranport properties.
Ph.D. in Chemistry, May 2018
Show less

Title: LENGTH DEPENDENT ACTIVATION IN MANDUCA SEXTA SKINNED FLIGHT MUSCLE
Creator: Wu, Yihong
Date: 2018, 2018-05
Description: The synchronous dorsolongitudinal muscle (DLM1) of the hawk moth, Manduca sexta has a number of characteristics similar to vertebrate cardiac...
Show moreThe synchronous dorsolongitudinal muscle (DLM1) of the hawk moth, Manduca sexta has a number of characteristics similar to vertebrate cardiac muscle. These muscles constitute a large proportion of the body weight and produce most of the force to depress the wings during flight. Crossbridges, consisting of myosin heads, form between the thin and thick filaments of the muscle fiber, and it is myosin head movement that causes muscle shortening and generates force. But the cycle cannot start without calcium bound to the troponin-tropomyosin complex, which expose the myosin binding sites on actin. It has been shown that cardiac muscle, as well as other muscles, exhibit myofilament length dependent activation where larger forces would be generated for a given calcium concentration at longer the sarcomere length (SL). The main goal in this thesis is to study the relationship of force-pCa of the DLM1 fibers as a function of sarcomere length. To establish these relationships, a series of calcium concentration solutions were prepared (pCa 4-8). The force was recorded as a function of the pCa at three different SL values. One aim of the thesis is to optimize the procedure for activation of the muscle fibers. Two different experimental protocols were used and their results were compared. The force-pCa relationships were plotted and fit to the Hill equation to analyze the cooperativity. The SL giving the highest force was 3.2 μm and the force-pCa relationship showed a sigmoidal shape with pCa50 of 6.01and the Hill coefficient was 19.6. Two protocols that were tried did not yield significantly different results, but no clear trends indicating myofilament length dependent activation were seen in these experiments in Manduca sexta flight muscle. However, protocol 2 showed a clearer demonstration of the cooperativity of the force-pCa relationships. The protocols used have better calcium binding to troponin-C (TnC) and larger Fmax than previous work in Irving lab. Future studies would be adding more data points with protocol 2 and analyzing if the trend changes.
M.S. in Molecular Biochemistry and Biophysics, May 2018
Show less

Title: SYNTHESIS AND REACTIVITY OF ORGANOMETALLIC VAPOR PRECURSORS IN DEPOSITING THIN FILM MATERIALS
Creator: Zhang, He
Date: 2018, 2018-05
Description: Developing novel vapor precursors for vapor depositions such as atomic layer deposition (ALD) is critical for enabling new thin film materials...
Show moreDeveloping novel vapor precursors for vapor depositions such as atomic layer deposition (ALD) is critical for enabling new thin film materials and advanced processes. 2D materials such as transition metal dichalcogenides (TMDs) are promising materials for TFETs and diffusion barriers due to their narrow, direct band gap, and atomic thickness. In the potential electronic applications of TMDs materials, low-temperature, non-corrosive process is desired and even required to avoid thermal budget to the devices and sensitive components. Besides novel organometallic precursors, understanding the surface reaction mechanism is also necessary to achieve well-controlled material growth and obtain crystalline materials at lower temperature. In this dissertation, two novel synthetic methods to obtain crystalline TMDs materials such as tungsten disulfide (WS2) were developed, utilized metal hydride compound to synthesize at room temperature and heteroleptic compound to illustrate reaction mechanism. Reaction mechanism on the surface to produce metals chalcogenides including oxidation state changes and ligand behaviors during the nucleation using organometallic precursor on surfaces were investigated and observed with synchrotron X-ray absorption spectroscopy (XAS). Conventional tellurium sources have very limited reactivity towards tungsten. To overcome the low reactivities between W and Te sources, redox potential of organometallic Te and W precursors was utilized and achieved low-temperature synthesis of tungsten ditelluride (WTe2). Novel heteroleptic precursors design was also extended to Zr and Hf precursors. Heteroleptic Zr and Hf precursors were synthesized with high volatility and thermals stability. The heteroleptic precursors also showed high reactivity toward proton sources and selectivity between ligands. Metal chalcogenides deposition would be preferred with oxygen-free precursors. Organometallic precursors are typically more reactive than simple metal carbonyls or metal halides, and those organometallic precursors with a clear proton-transfer mechanism can allow ligands to be removed easily and obtain materials with high purity. Currently, tungsten precursors to synthesis TMDs material are commonly limited in metal carbonyls and metal chlorides, and the sulfurizations were performed at high temperature. By using more reactive organometallic precursors, the reaction between tungsten and chalcogenide sources can be initiated at lower temperature, highly reactive metal hydride and redox potential of metal complex were also utilized to boost reactivity. Well-designed ligands structures were employed to chemically enhance the crystallinity through the selectivity between ligands. Heteroleptic precursors are typically expected to have a better self-limiting control in synthesis, due to the different type of ligands could selectively react in each step. These enhanced precursor chemistries and understanding mechanism lead to better control of the synthesis of materials.
Ph.D. in Chemistry, May 2018
Show less

Title: THE CHOLESTEROL LOWERING EFFECTS OF STRAWBERRY: A RANDOMIZED CONTROLLED TRIAL ESTABLISHING STRAWBERRYS' ROLE IN CARDIOVASCULAR HEALTH
Creator: Huang, Leailin
Date: 2018, 2018-05
Description: Cardiovascular diseases (CVD) represent the principal cause of morbidity and mortality worldwide. Recent studies suggest fruit and vegetable...
Show moreCardiovascular diseases (CVD) represent the principal cause of morbidity and mortality worldwide. Recent studies suggest fruit and vegetable consumption, especially berries, such as strawberry, is associated with lower risk of developing CVD. However, clinical trials demonstrating the specific risk factors affected by strawberry intake are not conclusive at present. Therefore, the objectives of this study were to assess strawberry intake on lipid and lipoprotein profile, endothelial function and blood pressure in individuals with moderate hypercholesterolemia. Thirty-four subjects (n=34) contributed to this analysis. This study was a randomized, double-blinded, placebo-controlled, cross-over, 12 week intervention design. Subjects were randomized to 1 of 2 study sequences in a 1:1 ratio. Sequence 1 was strawberry beverage, followed by 4 week wash out and crossover to placebo beverage. Sequence 2 was placebo beverage, followed by 4 week wash out and crossover to strawberry beverage. Subjects incorporated the strawberry or placebo beverage into their diet regularly (twice per day). Beverages were made from freeze-dried strawberries or a sensory and energy matched placebo powder. Strawberry containing beverages contained the equivalent of ~1.75 servings of fresh strawberries/beverage. Blood collection, anthropometrics, blood pressure and flow-mediated vasodilation (FMD) of the brachial artery were measured at baseline (week 0) and week 4, week 8 and week 12. Study findings showed that strawberry supplementation had overall treatment effects on increasing %FMD and decreasing systolic blood pressure compared to placebo (p=0.0096 and p=0.048, respectively). The 4 weeks strawberry supplementation did not significantly change anthropometric measures, lipid profile, glucose, insulin, and hs-CRP compared to placebo (p>0.05, all). Thus, strawberries may improve endothelial function and blood pressure, independent of other metabolic alterations, and may be considered an important fruit to include in a heart healthy diet in overweight or obese subjects with moderate hypercholesterolemia.
M.S. in Food Safety and Technology, May 2018
Show less

Title: CAREGIVERS OF TRANSITION-AGE YOUTH WITH INTELLECTUAL AND DEVELOPMENTAL DISABILITIES: THE ROLE OF SELF-COMPASSION BETWEEN STIGMA AND PSYCHOLOGICAL ADJUSTMENT
Creator: Ivins-lukse, Melissa Nicole
Date: 2018, 2018-05
Description: Family caregivers of youth with intellectual and developmental disabilities (IDDs) often serve as life long caregivers for their family...
Show moreFamily caregivers of youth with intellectual and developmental disabilities (IDDs) often serve as life long caregivers for their family members. Little is known about the experiences of these caregivers during their youths’ transitional phase between adolescence and adulthood, particularly with regard to their experiences of selfcompassion, courtesy stigma, and wellbeing. As courtesy stigma (stigma experienced as a result of a person’s connection to a stigmatized individual) is associated with a variety of negative outcomes for caregivers, it is essential to identify protective factors to buffer caregivers from these effects. The present study surveyed 130 family caregivers of transition age youth with IDDs and tested positive aspects (“self-kindness”) and negative aspects (“self-coldness”) of self-compassion as potential mediators between courtesy stigma and caregiver psychosocial outcomes. Self-coldness partially mediated the relationship between courtesy stigma and caregiver life satisfaction (effect = -.13, CI = -.28 to -.03), while self-kindness did not. Both self-kindness (effect = .10, CI = .02 to .21) and self-coldness (effect = .17, CI = .07 to .30) partially mediated the relationship between courtesy stigma and caregiver depressive symptoms. Overall self-compassion (positive and negative aspects combined) was tested as a moderator of the relationships between courtesy stigma and caregiver psychosocial outcomes; no significant interactions were observed. Findings suggest self-compassion offers some protective effects from courtesy stigma for caregivers. Future research should seek to explore potential differences in these relationships according to caregiver gender or care recipient diagnostic group.
M.S. in Psychology, May 2018
Show less

Title: ADAPTIVE QUADRATURE WITH A GENERAL ERROR CRITERION
Creator: Lu, Jiazhen
Date: 2018, 2018-05
Description: Numerical algorithms are required when the solutions to mathematical problems cannot be expressed analytically. Adaptive algorithms expend the...
Show moreNumerical algorithms are required when the solutions to mathematical problems cannot be expressed analytically. Adaptive algorithms expend the right amount of computational e↵ort to meet the error tolerance–easy problems require less e↵ort and hard problems require more e↵ort. Here we introduce a new globally adaptive trapezoidal rule algorithm satisfies a general error criterion, which includes both absolute and relative error tolerances. Then we derive the computational cost of the new algorithm and the complexity of this problem.
M.S. in Applied Mathematics, May 2018
Show less

repository.iit

Search the repository

Pages

Pages