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Title: ENHANCEMENT OF BIODESULFURIZATION IN RHODOCOCCUS SPECIES (IGTS8) BY THE EXPRESSION OF VITREOSCILLA HEMOGLOBIN
Creator: Shivdas, Vrushali D.
Date: 2013, 2013-07
Description: The bacterium Rhodococcus sp. IGTS8 contains the dsz operon, which encodes a three enzyme pathway (the “4S pathway”) that is able to...
Show moreThe bacterium Rhodococcus sp. IGTS8 contains the dsz operon, which encodes a three enzyme pathway (the “4S pathway”) that is able to mineralize the sulfur contained in dibenzothiophene (DBT), an organic sulfur containing molecule found in petroleum. The gene vgb, which encodes Vitreoscilla hemoglobin (VHb), has shown wide usefulness in enhancing productivity and other useful properties when expressed in heterologous hosts. We engineered strain IGTS8 to express VHb and measured the effects on growth and desulfurization of DBT, using minimal medium containing DBT as the sole source of sulfur. VHb was clearly detected in the engineered strain using the standard COdifference spectral analysis, but its level (0.38-0.63 nmoles/gm wet weight of cells) was about 10-fold lower than commonly seen for expression of VHb in other heterologous bacterial hosts. The VHb-expressing strain was tested for growth at both low and high aeration in minimal medium containing DBT as sole sulfur source; growth was about 50% lower at low aeration compared with high aeration. Despite this, metabolism of DBT (as detected by accumulation of the end product of the 4S pathway, 2-Hydroxy biphenyl (2-HBP), in the growth medium) was about 30 % higher in the low aeration compared to the high aeration culture. A possible explanation for these results is direct enhancement of the first two (monooxygenase) steps in conversion of DBT to 2-HBP. It was thus concluded from the studies that the expression of vgb in Rhodococcus sp. IGTS8 enhances the process of biodesulfurization under conditions of low aeration
M.S. in Biology, July 2013
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Title: DEVELOPMENT OF COMPUTER-AIDED DIAGNOSIS METHODS IN MAMMOGRAPHY
Creator: Wang, Juan
Date: 2015, 2015-12
Description: Computer-aided diagnosis (CAD) is developed as a diagnostic aid to provide a “second opinion” in diagnosis of breast cancer in early stage....
Show moreComputer-aided diagnosis (CAD) is developed as a diagnostic aid to provide a “second opinion” in diagnosis of breast cancer in early stage. Clustered microcalcifications (MCs) can be an important early sign of breast cancer. The goal of this work is to develop automatic CAD methods in mammography for breast cancer. Its contribution consists of both development of machine learning algorithms and study of related issues in detection and diagnosis of breast cancer with clustered MCs. First, a bi-thresholding scheme is proposed for reduction of false-positives (FPs) associated with linear structures in MC detection. An unified classifier with dummy variable modeling is further developed to reduce the FPs caused by both linear structures and MC-like noise patterns. It is demonstrated that both of the proposed algorithms can reduce FPs in MC detection, and thus, improve the detection accuracy significantly. Second, a spatial density modeling approach is investigated to quantify the spatial distribution of the MCs in a cluster when the MC detection is inaccurate. A spatial density function (SDF) is defined such that the extracted features are more robust to the presence of FPs and false-negatives (FNs) in MC detection. The results show that the features extracted from the SDF can achieve better class separation while being robust to the variations in MC detection when compared with those extracted from a traditional region-based method. Third, a retrieval-boosted approach is studied to discriminate between the benign and malignant MC lesions. A retrieval strategy is proposed to boost the classification performance by taking into account the similarity both in image features and in pathology. An adaptive Adaboost classifier, which can be adapted to the retrieved cases at a low computational cost, is applied to demonstrate the benefit of the retrieval strategy. The results show that the retrieval-boosted approach can signifishow that the features extracted from the SDF can achieve better class separation while being robust to the variations in MC detection when compared with those extracted from a traditional region-based method. Third, a retrieval-boosted approach is studied to discriminate between the benign and malignant MC lesions. A retrieval strategy is proposed to boost the classification performance by taking into account the similarity both in image features and in pathology. An adaptive Adaboost classifier, which can be adapted to the retrieved cases at a low computational cost, is applied to demonstrate the benefit of the retrieval strategy. The results show that the retrieval-boosted approach can significantly outperform its baseline classifier and that inclusion of pathology information in the retrieval can further improve the classification accuracy. Fourth, the perceptual similarity of MC lesions by radiologists is studied. The issues investigated include the degree of variability in the similarity ratings, the impact of this variability on agreement between readers in retrieval of similar lesions, and the factors contributing to the readers’ similarity ratings. The results indicate that perceptually similar lesions could be of diagnostic value in diagnosis for clustered MCs. Fifth, the feasibility of modeling the perceptual similarity of MC lesions is investigated. A support vector regression (SVR) is applied to model the perceptual similarity of clustered MCs, and a feature saliency analysis derived from SVR is used to determine the most relevant image features among a large set of candidate features. The results demonstrate that the relevant features are consistent in radiologists’ similarity ratings among different MC lesions, indicating that the perceptual similarity of MC lesions by radiologists can be effectively modeled. Finally, whether retrieval of similar images can effectively assist radiologists in diagnosis of clustered MCs is investigated. A retrieval system for relevant images is designed by considering both perceptually similar image features and the likelihood of malignancy of the lesion under consideration. An observer study is conducted to evaluate the diagnostic value of the proposed retrieval system. The results indicate that the proposed retrieval system has the potential to improve the reader’s ability in diagnosis of breast cancer with clustered MCs.
Ph.D. in Electrical Engineering, December 2015
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Title: CHANGES OF BACTERIAL SPECIES AND HEME PROTEIN OCCURRENCE IN ACTIVATED SLUDGE COMMUNITIES CULTURED IN THE LABORATORY
Creator: Wang, Xiaomeng
Date: 2016, 2016-05
Description: An activated sludge sample that had originally been collected from an aeration tank of the Stickney wastewater treatment plant in Chicago, and...
Show moreAn activated sludge sample that had originally been collected from an aeration tank of the Stickney wastewater treatment plant in Chicago, and had previously been cultured at low dissolved oxygen (DO) for 48 weekly passages was used as starting material for continuation of the low DO acclimation. The culture was continued at low dissolved oxygen in synthetic wastewater for 25 additional weekly passages to study what would happen to the activated sludge if the low DO continued. In order to do that, some important data were measured during the culture, including the specific oxygen uptake rates (SOUR) which could reflect the ability of oxygen utilization, 16S rDNA information which could tell the community diversity of sludge, and the dominant species genome data which suggested what really happened to the sludge and some reasons. The results showed that SOUR decreased modestly during the course of low DO adaptation, which was contrary to the results of the previous study. There were significant changes in community structure with respect to bacterial species during the first fifteen additional passages. Species known to produce both flavohemoglobins (FHbs) and truncated hemoglobins (trHbs) were common at all passages tested, although the dominant species were totally different from passage to passage. Specifically, during the course of the experiment, the frequency of cells encoding an FHb decreased substantially, from 84% to 50%, while the percentage of cells encoding a trHb decreased slightly from 84% to 78%. The overall content in the culture of heme b (the heme type found in bacterial hemoglobins) decreased, however, during continuation of the low DO conditions. So it is indicated that the oxygen utilization ability of the activated sludge does not increase all the time.
M.S. in Biology, May 2016
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Title: OPTIMIZATION OF POWER TRENCH MOSFETS FOR HIGH EFFICIENCY SYNCHRONOUS BUCK CONVERTERS
Creator: Wang, Wendi
Date: 2016, 2016-05
Description: Synchronous buck converter might be one of the most widely used and fabricated circuitry in the world for its favorable trade-off on many...
Show moreSynchronous buck converter might be one of the most widely used and fabricated circuitry in the world for its favorable trade-off on many subjects. However, the ever higher operation frequency has lead to increasing power loss in power switches and imposed new challenge to MOSFET engineering. One promising alternative for the traditionally used trench MOSFET is the shield gate MOSFET. Shield gate MOSFET has superior conduction performance as well as fast switching transient response due to its Reduced Surface Electric Field (RESURF) effect. In recent years, characterization of power MOSFET has developed along with MOSFET technology itself. New Figure of Merits (FOMs) have come into people's sight as they serve as better standards to fully describe MOSFET's overall performance. Being the same case for many other device structures, this new characterizing system also puts advanced requirements to shield gate MOSFET. And one of the most crucial problems is the rather large output capacitance this structure is having. To improve the property of shield gate MOSFET and meet the requirements of new standards, several ways of structure refinement have been proposed in this work. Both shield gate MOSFET and conventional MOSFET rated at 40V have been designed and simulated in the second chapter. The outcome shows that shield gate MOSFET has superior performance in almost every respect except for its large output charge. Then new structure for COSS reduction has been introduced in the following section, with decrement of about 50% in QQS-1 being achieved. Finally, another issue that has been tackled with is the shoot through of synchronous buck converter. Equivalent circuit model for shoot through analysis is built in this section to study the effect of each parasitic element. And a p type pillar added structure has been verified as an effective way to suppress shoot through gate bounce.
M.S. in Electrical Engineering, May 2016
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Title: YIELD STRESS MEASUREMENTS USING NOVEL SQUEEZING FLOWS
Creator: Ward, Daniel
Date: 2015, 2015-12
Description: Techniques for measuring the yield stress of materials are numerous, but often plagued with diffculties and uncertainties in measurement. The...
Show moreTechniques for measuring the yield stress of materials are numerous, but often plagued with diffculties and uncertainties in measurement. The primary methods include shear rheometry and, more recently, squeezing ow. Shear rheometry requires care on the part of the experimentalist to generate uniform flow fields and avoid shear banding or wall slip which may interfere with measurements. Squeezing fow tests are often performed with poorly controlled boundary conditions creating complicated flow fields. Further, the effects of the experimental modifications made to produce these boundary conditions in measurements are often not investigated and simply ignored. The main objective of this study was to develop a novel measuring technique to study the yield stress behavior of a model material, Carbopol. First attempts were made towards a novel lubricant injection squeezing (LIS) ow technique based on the continuous lubricated squeezing ow (CLSF) setup, as well as a novel lubricant film squeezing (LFS) technique which will allow measurement of the yield stress without the complicated treatment of either the sample or experimental setup required by currently favored methods. The novel techniques were developed and validated by direct comparison with shear measurements, the current gold standard for determining yield stress. Common squeezing techniques for characterizing yield stress fluids were also compared and found to be inadequate and inconsistent when compared to the shear measurements. The results from this study showed that the LIS and LFS methods are able to qualitatively determine a yield stress, but further investigation is required before they can be achieve their full potential as viable methods for determine yield stress.
M.S. in Chemical Engineering, December 2015
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Title: EUTECTIC γ(NI)/γ′(NI3AL)-δ(NI3NB) POLYCRYSTALLINE NICKEL-BASE SUPERALLOYS: CHEMISTRY, PROCESSING, MICROSTRUCTURE AND PROPERTIES
Creator: Xie, Mengtao
Date: 2012-12-03, 2012-12
Description: Directionally solidified γ(Ni)/γ′(Ni3Al)-δ(Ni3Nb) eutectic alloys possess attrac- tive high temperature mechanical properties and were...
Show moreDirectionally solidified γ(Ni)/γ′(Ni3Al)-δ(Ni3Nb) eutectic alloys possess attrac- tive high temperature mechanical properties and were considered as candidate tur- bine blade materials. Currently, the properties of polycrystalline γ/γ′-δ alloys are of interest as they inherit many advantageous attributes from the directionally solidi- fied γ/γ′-δ alloys, including high volume fraction of reinforcing phases, exceptional thermal stability and resistance to segregation-induced defect formation. If these at- tributes are properly harnessed, these γ/γ′-δ eutectic alloys might provide a unique solution to the problems experienced by traditional γ/γ′ polycrystalline Ni-base su- peralloys. This thesis is therefore dedicated towards the development of a funda- mental understanding of this novel class of eutectic alloys from several important perspectives. To enrich our understanding of this alloy system, this thesis will first be focused on quantifying the specific effect of individual alloying element on this γ/γ′-δ eutectic system. A set of quaternary Ni-Cr-Al-Nb alloy compositions with increasing levels of Chromium(Cr) was designed to investigate the detailed influence of this element on the primary phase formation, solidus and liquidus temperatures and γ-δ eutectic morphology. The alloying effect of Tantalum(Ta), which shares many similarities to Niobium(Nb), was studied by designing a matrix of multi-component γ/γ′-δ alloy compositions with nominally the same overall (Ta+Nb) content but varying Ta/Nb ratios. Here, different solidification segregation and solid state partitioning behaviors of Ta and Nb in this γ/γ′-δ eutectic system will be discussed, as well as the influ- ence of Ta/Nb ratio on solidification characteristics and equilibrium/non-equilibrium phase volume fractions. Thermodynamic calculations using the Computherm Pandat database (PanNi7) were compared to experimental results in these investigations. The second part of this thesis will aim to provide a more general understand- xvii ing of the effect of various alloying elements, including Cr, Co, Al, Ti, Mo, W, Ta and Nb, on this γ/γ′-δ system. A large number of experimental γ/γ′-δ alloys covering a broad range of compositions was selected for the analysis in this study. Important alloy attributes, such as primary phase formation, overall δ volume fraction, phase transformation temperatures and ternary eutectic initiation, were quantitatively char- acterized as a function of individual alloying element concentrations or combined con- tent of more elements. Linear regression analysis was performed to reveal the relative effectiveness of these elements on this eutectic system. Meanwhile, an extensive com- parison between the experimental observations and Pandat predictions was provided to critically evaluate the strength and weakness of existing thermodynamic database model in predicting trends in this eutectic alloy system with substantially higher Nb content compared to traditional γ/γ′ superalloys. The last part of this thesis emphasizes the development of cast and wrought manufacturing processes for cast γ/γ′-δ eutectic alloys as a cost effective alternative to the powder metallurgy route. Hot rolling of workpieces encapsulated within a steel can was performed on a simple model cast γ/γ′-δ alloy (897) to stimulate the ingot to billet. The influence of different deformation levels on breaking down the dendritic structure and promoting fine and homogenized microstructure was investi- gated. The mechanical soundness associated with different microstructures generated by different hot rolling processes was compared via compression and creep testing. Microstructural parameters that contribute to better mechanical properties will be discussed.
PH.D in Materials Science and Engineering, December 2012
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Title: DIRECTED EVOLUTION TO IMPROVE BIODESULFURIZATION OF PETROLEUM
Creator: Khayyat, Naghmeh Hassanzadeh
Date: 2013, 2013-12
Description: Dibenzothiophene (DBT) is an organosulfur compound found in petroleum that is refractory to the current hydrodesulfurization (HDS) method in...
Show moreDibenzothiophene (DBT) is an organosulfur compound found in petroleum that is refractory to the current hydrodesulfurization (HDS) method in refineries and raises the need for alternative methods such as biodesulfurization. Rhodococcus erythropolis strain IGTS8 naturally contains a dszABC operon, which encodes enzymes that can desulfurize DBT through the 4S pathway. Desulfurization-negative Rhodococcus opacus was transformed with plasmids pRESXdszABC and pRESXdszAS1BC, conferring the ability to desulfurize DBT. pRESXdszAS1BC had been modified from pRESXdszABC by placing a synthetic “sulpeptide gene” (S1) within the operon between dszA and dszB; S1 encodes a short polypeptide with high methionine and cysteine content, which puts additional sulfur demands on the 4S pathway when DBT is the only source of sulfur. Here we performed directed evolution on the two transformed R. opacus strains for 50 passages in a minimal (CDM) medium with DBT as the sole sulfur source in an attempt to drive evolution of greater DBT desulfurization activity. Desulfurization specific activity experiments were performed every 4 to 10 passages to compare the specific activities of these strains through the production of 2-HBP as measured by the Gibbs assay. Desulfurization positive strain Rhodococcus erythropolis IGTS8 was used as the control culture. R. opacus/pRESXdszABC demonstrated a maximum increase of 28-fold in desulfurization specific activity after 40 passages to a level as high as that of the control culture R. erythropolis IGTS8. Thereafter (passages 41-50), there was a 7% decrease from the maximum of desulfurization activity level (passage 40). R. opacus/pRESXdszAS1BC, however, showed only a maximum increase of 4-fold in specific activity after 37 passages. Moreover, there was a 61% decrease from the ix maximum of desulfurization activity level (passage 37) thereafter (passage 38-50). These could be due to the unexpected mutations and/or epigenetic changes in the pRESXdszAS1BC plasmid or host genomic sequences. Further DNA sequence analysis will be helpful in identification of these possible mutations.
M.S. in Biology, December 2013
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Title: BIODESULFURIZATION IMPROVEMENT OF A SYMBIOTIC PAENIBACILLUS CULTURE UTILIZING VITREOSCILLA HEMOGLOBIN
Creator: Liu, Benjamin Kwan
Date: 2015, 2015-05
Description: Biodesulfurization (BDS) of petroleum has been investigated as an alternative method to conventional chemical desulfurization for many years....
Show moreBiodesulfurization (BDS) of petroleum has been investigated as an alternative method to conventional chemical desulfurization for many years. Despite its potential to be an environmentally benign method, it has not been developed sufficiently to be useful in real world applications. This is due to its low efficiency and the necessity for it to work at temperatures high enough to lower the viscosity of petroleum so that mixing can be achieved. This study places the spotlight on two strains of Paenibacillus isolated in our laboratory that, together, possess biodesulfurization ability at moderately high temperatures and attempts to enhance biodesulfurization by expression of Vitreoscilla hemoglobin (VHb) in the Paenibacillus strains. The effects of expression of the VHb gene (vgb) on growth and desulfurizing activity was examined in a symbiotic system between the Paenibacillus strains 32O-Y and 32O-W. Of the two, 32O-Y is the one with the ability to metabolize dibenzothiophene (DBT), a common compound in petroleum that contains organic sulfur, while 32O-W enhances this ability, forming a symbiotic relationship between the two. The transformant of 32O-Y bearing vgb cloned into the shuttle vector pNW33N had been previously constructed in our laboratory. Presence of pNW33N-vgb was verified in one strain of 32O-Y through isolation of DNA, PCR, and gel electrophoresis. Mixtures of 32O-Y/32O-W or 32O-Y[pNW33N-vgb]/32O-W were cultured in minimal medium (CDM) with DBT as the sole sulfur source and subjected to multiple trials of growth and assay of DBT metabolism at varying temperatures. At 45 ˚C there was a substantial increase in both growth and DBT metabolizing coincident with VHb expression, whereas at lower (37 ˚C) and higher (50 ˚C) temperatures, VHb expression had little to no effect on either parameter. For both growth and DBT metabolism tested at 37 ˚C, 45 ˚C and 50 ˚C the highest absolute levels were seen at 37 ˚C, and the lowest at 45 ˚C.
M.S. in Biology, May 2015
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Title: INVESTIGATION OF THE EFFICACY OF REACTIVE OXYGEN SPECIES GENERATED BY BOVINE AORTIC ENDOTHELIAL CELLS FOR INITIATING FREE-RADICAL POLYMERIZATION
Creator: Lu, Chenlin
Date: 2013, 2013-12
Description: Reactive oxygen species are reported to be generated by bovine aortic endothelial cells during ischemia followed by reperfusion. This...
Show moreReactive oxygen species are reported to be generated by bovine aortic endothelial cells during ischemia followed by reperfusion. This biological response, believed to be the cause of post-ischemic reperfusion injury, inspired us to investigate the possibility of coupling it with the initiation of free-radical polymerization to produce polymer hydrogels for cell encapsulation. In this work, the generation of reactive oxygen species during ischemia and reperfusion was examined by fluorescence detection and the feasibility of initiating free-radical polymerization by generated reactive oxygen species was investigated in two sets of experiments. The generation of reactive oxygen species by bovine aortic endothelial cells when subjected to anoxia followed by reoxygenation was investigated in both attached and suspended cells. Both intracellular and extracellular generations of ROS appeared to occur in the experiments of attached cells. Cell viability experiments demonstrated that the generation of ROS was sufficient to cause cell damage and death. The feasibility of initiating free-radical polymerization by reactive oxygen species generated by bovine aortic endothelial cells subjected to anoxia followed by reoxygenation was investigated in two sets of experiments. One set involved the linear polymerization of NVP which allowed us to quantify the extent of polymerization and characterization of the weight conversion of PVP polymer. The other set involved the formation of PEGDA hydrogels which were characterized by imaging and staining methods. To our knowledge this is the first evidence of cell induced polymerization initiated by reactive oxygen species and gelation which can be used for a variety of biomedical applications.
M.S. in Chemical and Biological Engineering, December 2013
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Title: GENOME ANNOTATION AND PHYLOGENETIC ANALYSIS OF 27 SALMONELLA STRAINS BASED ON BIOINFORMATIC ANALYSIS OF RESPECTIVE GENOMES AND THREE GENES
Creator: Li, Xinyue
Date: 2013-04-15, 2013-05
Description: Salmonella is the most common food-borne bacterial infectious pathogen worldwide. Different serovars of Salmonella are capable of infecting...
Show moreSalmonella is the most common food-borne bacterial infectious pathogen worldwide. Different serovars of Salmonella are capable of infecting different kinds of hosts, such as humans, mice, pigs, chickens, and can also lead to different syndromes, such as enterica fever, enterocolitis and diarrhea, bacteremia and chronic asymptomatic carriage. Although Salmonella strains are quite diverse, strains within the same serovar usually infect the same host and cause similar symptoms. Thus, it is important, especially in food-borne disease outbreaks, to know which type of Salmonella is present. The current method of typing Salmonella is based on the Kaufmann-White scheme and MLEE, which are laborious and expensive. Although the reliability of this method has not been previously verified, the evolutionary relationship reflected by phylogenetic trees can be a possible alternative to the way of typing the Salmonella strains; this method would be less labor intensive and more economical. MLST is considered as a “gold standard” of typing for many species includes Salmonella. And genome sequence, which certainly reflects the evolutionary relationship of strains, is the most ideal data to construct a more reliable phylogenetic tree; however, genome sequencing is also a laborious and expensive process. Thus, conserved and ubiquitous gene data, which can be accessed with little effort, are generally used to minimize cost. Using16s rRNA is the most widely used method. In this study, 27 Salmonella genome sequences are annotated with RAST, and phylogenetic trees are constructed using three software, (phylip3.69, MEGA5.1, and CVTree). And MLST is also used to construct phylogenetic tree in this study, and the result is used to be compared with genome phylogenetic tree to find a more reliable reference tree. Although Neighbor-Joining method is the only algorithms x available in CVTree, phylip3.69 and MEGA5.1 are capable to use three separate algorithms(Maximum Parsimony, Maximum Likelihood, and Neighbor-Joining, respectively). Finally, these trees are compared in an effort to find a good alternative to replace the reference phylogenetic tree. In this study, it was determined that the groEL gene would be the best replacement.
M.S. Biological and Chemical Sciences, May 2013
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Title: INCORPORATING REACTIVE POWER MARKET INTO THE DAY-AHEAD ELECTRICITY MARKET
Creator: Al Ghamdi, Mohammed
Date: 2012-05-29, 2012-07
Description: The research work presented in this thesis proposes the incorporation of the reactive power market into the day-ahead electricity market in...
Show moreThe research work presented in this thesis proposes the incorporation of the reactive power market into the day-ahead electricity market in order to compensate generation companies (GENCOs) and independent power producers (IPPs) for providing any additional reactive power support, which varies on an hourly basis based on the load demand, transmission network configuration, and any contingencies that might occur. This proposal would minimize the total payment burden on the independent system operator (ISO), which is related to the reactive power dispatch. The proposed model achieves the main objective of an ISO in a competitive electricity market, which is to provide the required reactive power support from generators at minimum cost while ensuring the secure operation of the power system. In this research, the reactive power price is the bidding-based price that is submitted by the GENCOs and IPPs to the ISOs during the day-ahead market. The proposal takes into the account both the technical and economic aspects associated with the active power and reactive power dispatch in the context of the new operating paradigms in competitive electricity markets. In this research, the Security Constrained Unit Commitment (SCUC) based on AC power flow modeling is considered as the drive engine for clearing the day-ahead electricity market based on the amount of information provided by the market participants. This proposed framework would provide appropriate reactive power support from service providers at minimum cost, while ensuring the secure and reliable operation of the electrical power system. In the research, the PQ capability curves of the generating units are modeled to ensure the practically of the SCUC solutions that are obtained. This proposal would be an essential step toward a fair electricity market while increasing the security of the power system and reducing transmission congestions. Also, it would pave the road for various renewable energy resources since the penetration of renewable energy resources would impact the commitment of the generating units. This would impact the available reactive power reserve margin and security of the network. In addition, incorporating the reactive power market into the day-ahead market would provide a clear signal for optimal private investment in the reactive power capacity. The framework that has been developed is general in nature and can be used for any electricity market structure.
Ph.D. in Electrical Engineering, July 2012
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Title: USE OF AQUEOUS DISPERSIONS OF SDS MICELLES TO REMOVE BACTERIAL CONTAMINATION FROM FRESH PRODUCE AND FOOD CONTACT SURFACES
Creator: Han, Yibin
Date: 2013-04-30, 2013-05
Description: The current trend of increased consumption of fresh produce has coincided with an increase in foodborne illness resulting from fresh produce...
Show moreThe current trend of increased consumption of fresh produce has coincided with an increase in foodborne illness resulting from fresh produce consumption, which in turn has increased the amount of research directed at understanding the interactions between microbial pathogens and fresh produce. This dissertation examines the removal and inactivation of Escherichia coli O157:H7 and E. coli K12 from Romaine lettuce leaves and a model hydrophobic surface (polyvinyl chloride, PVC) using a nanofluid (a fluid containing nanometer-sized particles - in this case, sodium dodecyl sulfate, SDS) and its combinations with organic acids. A novel mechanism previously proposed by Wasan and Nikolov (D. T. Wasan & Nikolov, 2003) was used as the basis to explore the removal of bacteria from these surfaces by the aqueous dispersion of SDS micelles, and to explain how SDS plus levulinic acid at pH<3 improves inactivation of these bacteria. Examination of the bactericidal effect of levulinic acid, SDS, and their combination on E. coli O157:H7 attached to Romaine lettuce leaves revealed that using levulinic acid or SDS alone cannot effectively wash the bacterial cells from the surface or cause inactivation. However, combining them increased the effectiveness of the solution. The most effective combination of SDS plus acid for bacteria removal and inactivation among those we tested was found to be 0.06 mol/L SDS + 0.25 mol/L levulinic acid. This combination, which has a pH of 2.9, inactivated more than 5.2-log E. coli O157:H7 on a leaf surface, and similar results were achieved for E. coli K12 on a leaf surface, and for both E. coli O157:H7 and E. coli K12 on the surface of PVC. Surface and interface measurements, including x surface tension and contact angle, of washing solutions indicated that solutions containing SDS had a lower work of adhesion than those without the surfactant, which shows that a significant role of SDS in the inactivation mechanism is a weakening of the forces of attraction between the bacteria and the surface being cleaned. Our experiments also confirm that SDS likely plays a secondary role which depends on the solution pH. When the presence of an organic acid lowers the pH of the washing solution to below 2.6, the surface charge of E. coli O157:H7 changes from negative to positive (the pH is lower than the bacteria’s isoelectric point). In this case, we hypothesize that negatively-charged SDS molecules attach to the cells’ surfaces and inactivate the bacteria. This work provides additional insight into the complex nature of bacterial detachment from solid surfaces. Our work with aqueous dispersions of SDS micelles indicates how and why bacterial inactivation is increased through a combination treatment of SDS and an organic acid.
M.S. in Food Safety and Technology, May 2013
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Title: HOW HOSTILE CRITICISM RELATES TO HEALTH FUNCTIONING AND MARITAL ADJUSTMENT IN PATIENTS WITH CARDIOVASCULAR DISEASE AND THEIR PARTNERS
Creator: Hicks Iii, R. Elliott
Date: 2012-04-30, 2012-05
Description: Destructive communication and hostile interactions between spouses has been found to elicit large increases in systolic blood pressure, heart...
Show moreDestructive communication and hostile interactions between spouses has been found to elicit large increases in systolic blood pressure, heart rate, and cardiac output in patients (Nealey-Moore et al., 2007; Smith et al., 2009). This negatively impacts the cardiovascular health of the receiving partner. The present study was designed to assess the relationship between hostile criticism and patient report of marital satisfaction, physical health, and depressive symptomatology in a sample of couples participating in a cardiac risk reduction intervention. The current study uses archival data obtained during the Partners for Life cardiac risk reduction intervention for couples (Sher et al., 2002). Additionally, further observationally coded data was collected from video taped conversations recorded for the purposes of the Partners for Life study. Pearson correlation analyses indicate moderate negative relationships between Criticism and Marital Adjustment. Implications of these and other results are discussed.
M.S. in Clinical Psychology, May 2012
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Title: VITREOSCILLA HEMOGLOBIN: STRUCTURE-FUNCTION AND GENETIC ENGINEERING STUDIES
Creator: Li, Xiaodong
Date: 2014, 2014-05
Description: Paenibacillus strains 32O-W and 32O-Y were attempted to be transformed by electroporation with constructed plasmid pNW33N-vgb, modified to...
Show morePaenibacillus strains 32O-W and 32O-Y were attempted to be transformed by electroporation with constructed plasmid pNW33N-vgb, modified to contain the vgb gene which can be expressed as Vitreoscilla hemoglobin. Only attempts with 32O-Y were successful. Transformed 32O-Y/pNW33N-vgb was grown in CDM medium with dibenzothiophene (DBT) as the sole source of sulfur at different temperatures. Dramatic variability was observed in culture at different temperatures, so only the data at 45 °C was analyzed. The growth assay showed that the 32O-Y/pNW33N-vgb strain grew slower than untransformed 32O-Y, although Gibbs assay showed improvements in utilizing ability of DBT of 32O-Y/pNW33N-vgb compared to untransformed 32O-Y. This finding indicated that genetic engineering of introducing vgb into 32O-Y may cause deterioration in cell growth rate but improvement in desulfurization activities. Plasmid pUC-vgb-M2 was transformed into E. coli DH5α. The transformed DH5α/M2-vgb was cultured along with DH5α/pUC8:16, bearing plasmid pUC8:16 that was previously constructed in our lab and can be expressed to produce wild type VHb, and untransformed DH5α. CO-difference spectra were performed with the lysed cultures for the detection of VHb expression. As a result, DH5α/M2-vgb was confirmed to lack the ability to express functional VHb.
M.S. in Biology, May 2014
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Title: SUSTAINABLE NEW CITY MENTOUGOU, CHINA
Creator: Yin, Lu
Date: 2013-04-30, 2013-05
Description: This thesis will demonstrate one of the first urban models for the future of China’s growth. The Urban Operating System and GPS make the smart...
Show moreThis thesis will demonstrate one of the first urban models for the future of China’s growth. The Urban Operating System and GPS make the smart city smarter by linking up networks of billions of distributed sensors, systems, and intelligence across urban environments via city-scale operating systems. Personal Rapid Transit system runs everywhere and it is accessed and ordered by smart phone. Green belt is the medium that links all the natural area and parks in the city which become the core element in the city because it plays the most important role. Two types of transportation system including the Meglev for 10 minute access to Beijing and the PRT system for all internal urban mobility. The population of the new city is 80000. 80% of the people live here and work here, 20% of the people live here but work in Beijing. 30% of the people will use PRT system everyday. All the city blocks are mixed-use blocks. There are several types of residential buildings including mid-rise, high-rise and Beijing traditional courtyard house. This sustainable new city provides quality of lift to all the people live in the city.
M.S. in Architecture, May 2013
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Title: MANAGING STOCHASTIC WIND POWER GENERATION BY INCORPORATING DEMAND RESPONSE IN DAY-AHEAD SCHEDULING
Creator: Al Hassan, Hassan
Date: 2015, 2015-05
Description: This thesis proposes a stochastic algorithm for managing the variability of wind energy by incorporating hourly demand response in the day...
Show moreThis thesis proposes a stochastic algorithm for managing the variability of wind energy by incorporating hourly demand response in the day-ahead scheduling in power systems. Monte Carlo simulation with Latin hypercube sampling technique is applied to represent the uncertainties of wind energy via different wind scenarios. Demand response has several physical and operating constraints to be considered into the stochastic security-constrained unit commitment (SCUC) for economic, reliability, and security purposes. Benders decomposition method is applied to decompose the large-scale complex stochastic SCUC problem into several tractable problems. Different case studies are analyzed in this thesis to demonstrate the benefits of applying DR to the proposed day-ahead scheduling model with variable wind energy.
M.S. in Electrical Engineering, May 2015
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Title: BIO-COMPOSITE NANOMATERIALS; CHARACTERIZATION, MANIPULATION AND APPLICATION
Creator: Kim, Taeyoung
Date: 2013, 2013-05
Description: Biomaterials are any matter or material which interacts with biological system which were present on natural or synthetic nonviable materials....
Show moreBiomaterials are any matter or material which interacts with biological system which were present on natural or synthetic nonviable materials. An ideal biomaterial must physically and chemically compatible for biological applications to avoid toxicity and immune reaction. Collagen is a widely abundant, robust biopolymer that is found in the extracellular matrix (ECM) of many tissues. In terms of its structure and organization, collagen is a bio-nano material. The use of collagen in stem cell differentiation is particularly enticing since it is now evident that the extracellular matrix (ECM) proteins can regulate the cell’s fate and growth by their molecular and physical properties. In this thesis research, we have characterized the physical and structural properties of collagen and its composite materials. We found collagen interacts with NaCl and other nano-materials, such as carbon nanotube (CNT) and TiO2 nanotube, resulting in the modification of collagen structure and increase of its stiffness. In particular, CNT has changed collagen structure at both the molecular level and the higher organizational level. The effects of the matrices on cell growth and development were studied. It was found that collagen/CNT matrix specify and accelerate the stem cell differentiation toward neural cells. Since neurons form the foundation of biological circuit, manipulation of neurons in growth has the potential to form desired biological circuit. We also examined collagen in vaginal wall connective tissues, and found that alteration of collagen properties in clinical tissues is correlated to the onset of pelvic organ prolapse.
PH.D in Chemistry, May 2013
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Title: TENSIWALL
Creator: Chiu, Mark A.
Date: 2011-12-10, 2011-12
Description: A facade is the interface between building and environment, between indoor and outdoor; therefore it has a functional quality – protection of...
Show moreA facade is the interface between building and environment, between indoor and outdoor; therefore it has a functional quality – protection of the interior spaces, inhabitants, and services from the forces of the exterior surrounding environment. The facade is also the first component to be seen of any building; therefore it has a certain aesthetic quality that it needs to achieve. Currently, most facades are constructed of relatively heavy materials, requiring more structural material usage; and opaque materials, depriving the interior occupants of natural light. A textile facade, however, can provide a lightweight, lighttransmissive, and highly insulative exterior wall, while also offering versatility in the aesthetics. Although they are usually not considered to be a facade material, textiles can create a highly advanced alternative to the current facade solutions. Therefore, the thesis topic is to develop a future exterior wall system with advanced physical properties based on a textile facade.
M.S. in Architecture, December 2011
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Title: "NEW HORIZON" - SUSTAINABLE NEW CITY, DAHEJ, GUJARAT, INDIA
Creator: Suthar, Bhumika
Date: 2013, 2013-07
Description: The purpose of this thesis is to develop an ideal environment for developing new cities, that are not just green and clean but also self...
Show moreThe purpose of this thesis is to develop an ideal environment for developing new cities, that are not just green and clean but also self-sustainable. Current cities in world supports great infrastructure and accommodates approximately 6-7 Million people. According to UN, the population growth in next 15 years would be 10-15 million people will be living in the cities and that would increase loads on existing cities infrastructure. To avoid these inevitable circumstances we need new sustainable cities. In last two decades rapid urbanization and industrialization has caused indelible effects on our ecosystem. This thesis will provide in-depth insight on current urban problems and present a solution in form of new sustainable city. A holistic approach has been taken towards developing a new city at Dahej in Gujarat, India, which will be a prototype for new sustainable community development in future. It focuses on creating a perfect balance between environmental, social and economic sustainability. This new city will provide quality of life and environment. This thesis is a sincere approach to provide a strategic solution for post-carbon world and qualitative phenomena of the sustainable low-carbon future.
M.S. in Architecture, July 2013
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Title: Analysis of Maltese Cross Specimens to Determine Three-Dimensional Yield Surfaces
Creator: Chaudesaygues, Ludwig
Date: 2011-11-29, 2011-12
Description: Yield behavior of extremely porous solid foams under multiaxial states of stress is of significant importance because, unlike pressure...
Show moreYield behavior of extremely porous solid foams under multiaxial states of stress is of significant importance because, unlike pressure independent yield response of the majority of engineering materials, solid foams exhibit quadratic as well as linear dependence on hydrostatic stress component in their yield behavior. Therefore, there exists a critical need to analyze and use specimen geometries that allow biaxial and triaxial experiments through which yield surface can be probed under varying amounts of mean stress. This study investigates, through FE analysis, the feasibility of Maltese-Cross (MC) specimen geometry as a potential candidate for using in biaxial and triaxial experiments. Although solid foams have a pressure dependent yield behavior, the current study adopted a linear elastic-hardening J2 flow rule to keep the analysis reasonably simple and focus on the fundamental effect of specimen geometry on strain field and, more importantly, the extraction of yield point from multiaxial force-displacement data. One must recognize that in multiaxial experiments, particularly in triaxial loading, forces and displacements experienced by the nominal gage section cannot be directly measured for practical reasons. Instead, far field forces and displacements have to be used to calculate average measures of stress and strain within the gage section. This study shows through FE analyses that MC specimens can be used to determine the onset of macroscopic yielding under varying amount of mean stress component, provided that certain stress/strain paths, which cause premature deformation localization out of the gage section, are avoided.
M.S. in Mechanical and Aerospace Engineering, December 2011
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