2018 MU dissertations - Access restricted to MU
Permanent URI for this collection
Browse
Recent Submissions
Item Kinetics, mass transfer, and mass re-equilibrium for arsenate adsorption on iron oxide-based carbons(University of Missouri--Columbia, 2018) Wang, Zhengyang; Deng, Baolin[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] Removal of arsenic (As) from drinking water sources is much needed worldwide, and small water treatment systems, such as point-of-use (POU) treatment, could be an effective solution for residential applications. Adopting existing removal technologies that are successful in large-scale treatment to small-scale units, however, is rather ineffective due to the short hydraulic residence time in small water treatment systems. β¦ The Freundlich isotherm can fit experimental data well: a crossover point for the two fitted Freundlich isotherms was observed and nano-FeAC had higher adsorption plateau. Furthermore, we demonstrated that due to the MRE process, a pseudo-equilibrium of FeMC was altered to another steady state by an in situ extraction with nano-FeAC in both batch and column systems. The overall inter-medium mass transfer resulted in both improved adsorption densities obtained by batch tests and a large bed volume prior to the 10 [mu]g As/L breakthrough at a short empty bed contact time (0.85 min).Item Roles of clathrin-coated vesicle networks in plant immunity and development(University of Missouri--Columbia, 2018) LaMontagne, Erica Danielle; Heese, Antje[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] For a plant cell, the plasma membrane (PM) is not only the interface with its environment but also a signaling platform. Proteins localized to the PM serve important purposes including detecting bacterial pathogens in the apoplast, initiating defense signaling, and repressing defense signaling in the absence of pathogens to prevent unnecessary resource allocation. To effectively fulfill their roles, proteins with immune-related functions must be properly located at the PM and present in sufficient quantities. To coordinate delivery and removal of immune-related proteins to and from the PM, plant cells utilize an intricate internal vesicle trafficking system. Within a plant cell, a central organelle termed the trans-Golgi network/early endosome (TGN/EE) is a hub at which many of the vesicle trafficking routes contributing to modulating PM protein levels merge. It is established that clathrincoated vesicles (CCVs) form at both the PM and the TGN/EE. However, our knowledge of the roles TGN/EE-associated CCV components play in coordinating cellular logistics of immune-related proteins remains rudimentary. Here, we explore the roles of two CCV components for modulating PM abundance of protein cargoes with plant immune and developmental functions. In connection, we tested how loss of one or both CCV components impacted immune signaling and immunity against pathogenic bacteria. β¦ To complement discovery research in Arabidopsis, we aim to identify and characterize putative orthologs of FLS2 and EPS1 in the agronomically important species Zea mays (maize) in the long-term. Maize plants can perceive and respond to flg22 but the cognate receptor responsible for this recognition remains undefined. In addition, there is miniscule knowledge of vesicle trafficking components and their associated roles in maize. To provide insight to these large gaps in the field, we have identified ZmFLS2 and ZmEPS1 candidates through a bioinformatic approach. For each gene, we have isolated multiple putative null mutant alleles either from UniformMu stocks or through Ds mobilization and proceeded to introgress these mutant lines into the genetically uniform B73 reference genome. Genetic tools generated here will allow us to assess organismal, cellular, and molecular functions of ZmFLS2 and ZmEPS1 in future studies.Item Polyurethenae foams and engineering education(University of Missouri--Columbia, 2018) An, Siyu; Ghosh, Tushar K.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] Thermal conductivity [subscript] of a rigid polyurethane (PU) foam was successfully simulated, during which the impact of index of isocyanate, mixing speed, and the amount of physical blowing agent was characterized by a heat flow meter for [subscript], and a pycnometer for the foam density and closed cell content. Besides, heat capacities (πΆπ) of most common polyols and isocyanate in making PU foams were experimentally measured. Then a general formula was created for using in a Matlab code to boost efficiency of simulating the reaction temperature. This work laid the groundwork for modeling the viscosity, reaction rates, and concentrations of reactants, etc. Prior to this publication, it was assumed in our simulation code that πΆπ was a function of rising temperature by a slope of 0.1% per one degree for any polyols and isocyanate. In addition, a potential way to help undergraduates to achieve analysis, evaluation, and creation levels of learning in polymer and chemical reaction engineering course was presented.Item Antenna designs and imaging algorithm for radar-based microwave breast cancer detection(University of Missouri--Columbia, 2018) Al-Zuhairi, Dheyaa Tareq; Islam, Naz; Gahl, John[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] In this work, the design of ultra-wideband antennas and an algorithm for artifact removal and image reconstruction beamforming for microwave breast cancer detection were presented. A tapered slot antenna and a quad-ridge horn antenna are designed, simulated and tested, and a system for multistatic radar-based microwave tumor detection for both artifact removal and image reconstruction was proposed. The system can be fabricated as a portable electronic chip. This work incorporates antenna features required for radar-based microwave breast cancer detection through the design of an ultra-wideband tapered slot antenna embedded in a dielectric material and testing the antenna in the time domain, frequency domain and in imaging reconstruction. The analysis shows impedance matching over ultra-wide frequencies while maintaining a high gain with low distortion. Two imaging approaches were also proposed. Results validate the proposed design and the imaging approaches. A dual polarized quad-ridge horn antenna was also proposed, in which each flared ridge was fitted with a semi-elliptical metallic part to increase bandwidth and polarization isolation. Vertical and horizontal oriented field probes were used to test isolation between the polarization components. Results show an almost 40 dB isolation between the linear polarization signals with high gain and port to port isolation over the entire bandwidth. Following the excitation signal, the quad-ridged horn antennas show unwanted signals that persist for a long time. This interference needs to be removed for successful detection of the cancerous growth. Analysis shows that the sources of oscillating were from the antenna cavity resonance and the inherent antenna LC resonator. Solutions to remove or minimize these signals without affecting the antenna parameters were implemented. Modification of the cavity successfully suppressed the cavity oscillation and altering the antenna waveguide reduced inductance and thus mitigated LC oscillation. The time and frequency domain signals demonstrated the effectiveness of the proposed solutions. Furthermore, the proposed techniques enhanced image quality through clutter reduction. The proposed radar-based microwave breast cancer detection system removed undesirable artifacts from multistatic signals reflected from the breast. A heterogeneous breast phantom, with two tumors, were simulated. After the multistatic scan, the collected responses were divided into groups of highly correlated signals. A window function was derived from the signals to remove parts which had no target information. The signals in each group were processed using Wiener filter, and the processed signals of all the groups are then merged into one artifact-free data matrix. The signals from different scans were combined in the beamforming step. An improved beamforming imaging algorithm was also proposed. Results demonstrated the merits of the proposed method in removing the artifact in multistatic radar situation. Finally, the images demonstrated the effectiveness of the proposed algorithm in minimizing clutter and in determining the actual size of a breast tumor with low computational complexity.Item DNA interstrand crosslinks arising from DNA strand breaks at true abasic sites in duplex DNA(University of Missouri--Columbia, 2018) Yang, Zhiyu; Gates, Kent S.[ACCESS RESTRICTED TO THE UNIVERSITY OF MISSOURI-COLUMBIA AT AUTHOR'S REQUEST.] Abasic sites (apurinic/apyrimidinic sites, Ap sites) are one of the most common forms of lesions found in genomic DNA. For the past decade, Gates group has endeavored to identify DNA interstrand crosslinks arising from Ap sites, that are sources of endogenous interstrand crosslinks which relate to aging, cancer and neurodegenerative diseases. This thesis describes my work in this area, starting from studying the DNA strand cleavage at abasic sites via [beta]-elimination reaction, that can generate a family of structurally diverse sugar remnants at the 3' terminus of the nicked strand under physiological conditions. Using an in vitro system, I have characterized a series of DNA interstrand crosslinks arising from these single strand breaks, which structures are dependent on changing DNA sequence contexts and varied assay conditions that are all bio-relevant. These structures are novel and haven't been reported to the best of our knowledge. In the meantime, this work has highlighted amine catalysis in Michael addition, and brought to attention the role of GSH in the formation of complex DNA lesions.