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Title: DEVELOPEMNT OF A MULTI-HOP SMARTPHONE-TO-SMARTPHONE NETWORK
Creator: Guo, Daojing
Date: 2014, 2014-05
Description: As wireless communication is a main concentration of smartphone applications nowadays, people are trying to build wireless connection with...
Show moreAs wireless communication is a main concentration of smartphone applications nowadays, people are trying to build wireless connection with others to share data and communicate. Wi-Fi Direct is a new technology that has the ability to build wireless connection within a group of devices. Mobile Ad-hoc network is one important approaches in wireless Ad-hoc network. Several researches are focusing on creating a Mobile Ad-hoc network over Wi-Fi Direct with simulator. As supporting Wi-Fi Direct functions, Android platform provides a hardware environment. And until now, Android is the only platform supporting this latest technology, neither Blackberry and iOS. In this thesis, one Android application is made to explore the establishment of Mobile Ad-hoc network over Wi-Fi Direct. This thesis also discusses one potential fundamental of the framework about this network, including message exchange and routing protocols. Multiple Android smartphones (Nexus 5) are used to make some tests about establishing this network in a mobile devices.
M.S. Electrical Engineering, May 2014
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Title: ANALYZING THE LINGUISTIC CHARACTERISTICS OF MARIJUANA USE BY INCOME USING SOCIAL MEDIA
Creator: Zeinali, Sahand
Date: 2018, 2018-05
Description: Marijuana use and legality has been a widely-discussed topic in the recent years. Knowing that marijuana has different effects on health, mood...
Show moreMarijuana use and legality has been a widely-discussed topic in the recent years. Knowing that marijuana has different effects on health, mood and behavior after its use, it is important to understand what the underlying causes for marijuana use also are. As marijuana use is becoming more prevalent every day, it is crucial to know what the motives behind the users' tendencies are for smoking marijuana. To be able to identify the words/patterns associated with marijuana use prior to its use, we will need a real-time method to understand the problem on a deeper level with a better method than surveying users. In our study, we aim to understand the different linguistic characteristics of marijuana users based on their income. Social media's provision of data into understanding and tracking people's behavior can be very beneficial in understanding the contrast between the different social classes prior to marijuana use and understand what the underlying causes are for their marijuana use. In our experiment, we use social media to analyze the patterns and characteristics of marijuana use based on income class. By collecting data on Twitter, we then proceed to classify users based on their income. Using this method, we predict the income of each user by utilizing the user's Twitter activity and their linguistic characteristics based on the tweets associated with them. Through the experiment, we can identify patterns amongst the marijuana users in two different income classes and predict what class a user will be placed in based on their recent Twitter activity with a good accuracy.
M.S. in Computer Science, May 2018
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Title: OPTIMIZATION IN MULTI-RADIO MULTI-CHANNEL WIRELESS NETWORKS WITH DIRECTIONAL ANTENNAS
Creator: Zhou, Lei
Date: 2018, 2018-05
Description: In this thesis throughput optimal and delay minimization problems are discussed in multi-radio multi-channel (MRMC) wireless networks with...
Show moreIn this thesis throughput optimal and delay minimization problems are discussed in multi-radio multi-channel (MRMC) wireless networks with directional antennas (DR). As for throughput optimal problem, we adopt a multi dimensional conflict graph (MDCG) in MRMC-DR network under protocol interference model, using the concept of Link-Radio- Antenna-Channel tuple links, to facilitate mapping the original MRMC-DA network into a simple virtual single-radio single-channel (SRSC) network, on which the capacity optimization problem can be formulated as a linear program. To circumvent searching the exponentially many independent sets, we apply the delayed column generation (DCG) method to design our algorithm. On the other hand, with regard to delay minimization problem, we present a minimum length schedule (MLS) to minimize end-to-end delay while satisfying required demand. A tuple-based model is applied to help address this problem, and a more realistic model—physical interference model is adopted here to better present interference relationships between wireless links. DCG is also used here to avoid going through all independent sets, and different strategies have been raised to address situations with fixed transmission rate or variable transmission rate. Moreover, both routing and scheduling can be jointly achieved by searching for optimal solutions of our problem formulation.
Ph.D. in Computer Engineering, May 2018
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Title: New Housing Model "Flexible Housing Components:IMG_7336_EDIT_Crop"
Creator: Quinn, Aidan
Date: 2012-05-02, 2012-05
Description: This project is a focus on spatial flexibility. The idea is to generate housing components that focuses on flexibility in order to create...
Show moreThis project is a focus on spatial flexibility. The idea is to generate housing components that focuses on flexibility in order to create space that is defined by the user.
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Title: New Housing Model "Flexible Housing Components: IMG_7337_EDIT_Crop"
Creator: Quinn, Aidan
Date: 2012-05-02, 2012-05
Description: This project is a focus on spatial flexibility. The idea is to generate housing components that focuses on flexibility in order to create...
Show moreThis project is a focus on spatial flexibility. The idea is to generate housing components that focuses on flexibility in order to create space that is defined by the user.
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Title: Identity and Self-Efficacy Among Mathematically Successful African American Single Mothers in Urban Community College Contexts
Creator: Devi, Shavila
Date: 2019
Description: This dissertation is a phenomenological, multi-case study of 13 mathematically successful African American single mothers from two urban...
Show moreThis dissertation is a phenomenological, multi-case study of 13 mathematically successful African American single mothers from two urban community colleges in Chicago. While a number of recent studies have focused on Black girls and women in K-12 and university contexts, the community college context remains understudied despite the presence of large numbers of Black women. Moreover, there has been a tendency in mainstream research contexts to normalize failure, and focus on problematic aspects of being a Black single mother or being a Black mathematics learner. Bringing together considerations of identity (racial, mathematics, single mother) and mathematics self-efficacy, this study will be the first to focus on mathematically successful African American single mothers in the community college context. The following research questions guided the research for this dissertation:1. How do African American single mothers, who return to study mathematics at the community college and are successful in their courses, narrate their identities and life experiences around race, gender, mathematics learning, and being a mother?2. How do these women score on the Mathematics Self-Efficacy Scale (MSES) and what sources of and influences on their self-efficacy are reported by these women via interviews? 3. What other factors (intrapersonal and beyond) do these women report as being particularly salient in their mathematics success?Multiple forms of data–semi-structured interviews, pre-and-post responses to a widely-used mathematics self-efficacy survey, and mathematics artifacts–were collected to address the research questions. A cross-case analysis of the data revealed four themes that emerged across the 13 participants. Within-case analyses of three participants reveals how the themes play out in-depth for these women. The four themes are (1) strong counter-narratives of being a single mother that resisted dominant and deficit-oriented discourses; (2) education as a key tool and resource to manage and mitigate risks associated with single motherhood; (3) multifaceted stories of resilience to achieve success in mathematics and life; and (4) positive, success-oriented mathematics identities and positive math self-efficacy. This study contributes to an emerging success-oriented literature on Black women and mathematics, and a growing research literature on identity in mathematics education. In surfacing how the participants narrate and negotiate race, gender, and class, this dissertation also contributes to an emerging literature on intersectionality in mathematics education. Results from this study can inform community college administrators and faculty in crafting practice and policy to support African American single mothers in mathematics.
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Title: Masculinities in Games for Gay Male Audiences
Creator: DeAnda, Michael Anthony
Date: 2019
Description: Games offer a unique site to understand how culture operates and works upon us. With the recent push for more representation of LGBTQ bodies...
Show moreGames offer a unique site to understand how culture operates and works upon us. With the recent push for more representation of LGBTQ bodies and experiences in AAA games, queerness provides a necessary framework to critique the politics of these representations. In this project, I question the extent to which games marketed to gay men challenge or reify problematic values of heteronormativity and hegemonic masculinity. I argue that discussing representation in games necessitates interrogation beyond visual and narrative elements to include mechanics, constraints, rules, and systems. Here, I emphasize understanding how these components of games allow players to play with bodies or limit interactions in games and what these affordances/constraints relay about gender identity and sexuality. In my second chapter, I investigate how a game played on RuPaul’s Drag Race with male underwear models codes male/female binaries into gay sexuality. In Chapter 3, I analyze Drag Bingo through participant observation and oral histories with drag queen hosts and discuss how these hosts develop a liminal space in which players can joyfully play with gender and sexuality. I “close play” Robert Yang’s Cobra Club in Chapter 4, locating the game within the history of surveilling homosexuality. A design discussion of Bulge Lab, an Alternate Reality Game I developed that focuses on body image, masculinity, and viruses, comprises my fifth chapter.
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Title: EFFECTIVENESS OF CLEANING STRATEGIES FOR REMOVING MILK CHOCOLATE FROM PILOT-SCALE PIPE/VALVE ASSEMBLY AND CHOCOLATE PROCESSING EQUIPMENT
Creator: Zhang, Liyun
Date: 2019
Description: Dark chocolate manufactured on shared processing lines with milk chocolate is a high-risk food for consumers with milk allergy. Inadequate...
Show moreDark chocolate manufactured on shared processing lines with milk chocolate is a high-risk food for consumers with milk allergy. Inadequate cleaning of shared chocolate manufacturing equipment can result in milk contamination of subsequent products, and product recalls. Limited information is available on the effectiveness of different cleaning procedures for preventing the transfer of milk to dark chocolate processed on shared equipment. Pilot-scale experiments investigated the effectiveness of three dry cleaning methods: 1) no cleaning, 2) pig purging, and 3) a cocoa butter flush (40°C, 1 hour) for removing milk chocolate residue from a heated (40ºC) standard (1.5” OD) sanitary stainless steel pipe (30.5 cm length) and attached butterfly or ball valve. After cleaning, milk-free dark chocolate (~27 kg, 40°C) was pumped through the pipe/valve combination. Dark chocolate push-through samples were collected and analyzed for milk concentrations with a Neogen Veratox total milk ELISA kit. Experiments with no cleaning resulted in initial milk concentrations up to 6,070 (9.6% CV) ppm milk and up to 14,900 (0.3% CV) ppm milk for the pipe/butterfly valve and the pipe/ball valve, respectively. Cocoa butter recirculation through the pipe/butterfly valve decreased initial milk concentrations to 680 (10.3% CV) – 2720 (2.6% CV) ppm milk. Use of a pig purging dramatically reduced milk levels to 45 (4.3% CV) – 180 (15.7% CV) for the pipe/butterfly valve and below limit of quantification of ELISA (LOQ, 2.5 ppm milk) for the pipe/ball valve. After most cleaning treatments, > 14 kg of dark chocolate push-through was required to obtain milk levels < LOQ.A second set of pilot-scale experiments determined the efficacy of cleaning procedures for removing milk chocolate from selected chocolate processing equipment. Three cleaning methods explored removal of milk chocolate from a ball mill and conche: 1) no cleaning, 2) a cocoa butter flush (40°C, 5 min), and 3) wet cleaning (detergent-rinse-air dry). After cleaning, three batches of milk-free dark chocolate (40°C) were processed in the ball mill (~0.35 kg) and conche (2.5 kg), and each batch was collected and analyzed for milk. Milk chocolate (1.5 kg) was processed on a 3-roll refiner, followed by push-through with dark chocolate (~8 kg), with 0.3 kg samples collected at 5-min intervals. Milk was not detected (Show less

Title: SYNERGISTIC EFFECT OF FATTY ACIDS AND NISIN IN INHIBITING PERSISTER AND BIOFILM OF LISTERIA MONOCYTOGENES
Creator: Zhou, Jiacheng
Date: 2019
Description: A foodborne pathogen Listeria monocytogenes causes a life-threatening listeriosis in humans after eating contaminated food. The FDA-approved...
Show moreA foodborne pathogen Listeria monocytogenes causes a life-threatening listeriosis in humans after eating contaminated food. The FDA-approved antimicrobial peptide nisin has been used to prevent contamination of food product from Gram-positive pathogens including L. monocytogenes. However, the formation of biofilms and persisters (i.e., metabolically dormant bacterial population) has resulted in the failure of nisin treatment. Fatty acids, which have been known to exhibit antimicrobial activities, are widely used for therapeutics, food preservation, and agriculture. Previously, we found that two fatty acid compounds lauric acids and N-tridecanoic acids are effective in inhibiting biofilms and persister formation of Gram-negative pathogens. In this study, we investigate whether the fatty acid treatment in combination with nisin promotes inactivation of L. monocytogenes, especially biofilms and persisters. The fatty acid-only treatment reduced the level of biofilms and persisters, while nisin-only treatment resulted in the development of resistant population of L. monocytogenes ATCC19115 strain. However, the co-treatment of the fatty acid and nisin synergistically enhanced the killing of L. monocytogenes by significantly decreasing the number of survived cells and inhibiting biofilms. These results are particularly important in improving food safety in that the food-grade fatty acids can be applied to repress the occurrence of resistant mechanisms of foodborne pathogens by inhibiting biofilm and persister cell formation.
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Title: Language, Negative Affect, and Aggression in Children with Autism Spectrum Disorder
Creator: Dreher, Taylor
Date: 2019
Description: The goal of the present study was to use ecological momentary assessment to examine factors that predict aggression in children with Autism...
Show moreThe goal of the present study was to use ecological momentary assessment to examine factors that predict aggression in children with Autism Spectrum Disorder (ASD). In particular, this study sought to investigate the situation-level and person-level factors that predict the severity of children’s aggressive episodes. At the situation-level, we predicted that children would show more severe aggression after experiencing a negative affective state. At the person-level, we hypothesized that children with better grammatical and pragmatic language abilities would demonstrate less severe aggressive behavior. In addition, we predicted that language abilities would moderate the association between negative affect and aggression. We were unable to test these hypotheses due to a floor effect in the outcome variable. Thus, we conducted a series of analyses to examine how variables of interest were associated with the presence of aggressive behavior. We found an association between negative affect and aggression, such that children who experienced higher levels of negative affect were more likely to engage in aggressive behavior. However, there was not a significant relationship between language abilities and the presence of aggression. In addition, there was no evidence for a moderation effect. Future studies should examine other variables that may moderate or mediate the association between negative affect and aggression in children with ASD.
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Title: Inefficiencies in resource allocation games
Creator: Tota, Praneeth
Date: 2019
Description: This thesis addresses a problem that has been debated by the academic community, the government and the industry at large which is : How...
Show moreThis thesis addresses a problem that has been debated by the academic community, the government and the industry at large which is : How unfair is a tiered Internet compared to a open Internet ? On one hand we have an open Internet in which all the data is treated equally and the Internet service providers have no say when it comes to a pricing differentiation and on the other hand we have a tiered Internet in which the ISPs can charge different amounts based on certain constraints like the type of data or the content provider. The architecture of the internet imposes certain constraints which need mechanisms to efficiently allocate the resources among all the competing participants who only concern themselves with their best interests without considering the social benefit as a whole. We consider one such mechanism known as proportional sharing in which resource or the bandwidth is divided among the participants based on their bids. An efficient allocation is one which maximizes the aggregate utility of the users. We consider inelastic demand with the participants as price anticipating and ensure market clearing.We examine a tiered Internet in which the ISPs can partition the bandwidth based on certain constraints and charge a premium for better service. The participants involved are from all economic classes, so they have different amounts of wealth at their disposal. We quantify the relative loss incurred by the participants in lower economic classes as compared to the higher economic classes. We also calculate the loss of efficiency caused by competition among the participants as compared to the optimum social allocation.
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Title: IMPACT OF THERMAL AND HIGH PRESSURE PROCESSING ON THE ANTIGENICITY AND DETECTABILITY OF EGG AND MILK ALLERGENS
Creator: Yang, Shuopeng
Date: 2013, 2013-12
Description: Cow’s milk allergy and egg allergy are the two most prevalent food allergies in the United States. Enzyme-linked immunosorbent assay (ELISA),...
Show moreCow’s milk allergy and egg allergy are the two most prevalent food allergies in the United States. Enzyme-linked immunosorbent assay (ELISA), based on antigen-antibody reactions, is the most popular method used by the food industry to detect allergen residues. Thermal treatments are the traditional food processing methods, while high pressure processing (HPP) has increasingly been applied as an alternative food processing technology. This research examined how thermal and high pressure processing may affect the antigenicity and detectability of milk and egg allergens. The first part of this study examined the performance of four ELISA test kits (Veratox for Total Milk Allergen, Biokits BLG Assay Kit, ELISA Systems Casein and BLG Residue Assays) for quantitation of milk residues in packaged foods that have been subjected to different degrees of processing. Whether standard reference materials (SRM) can be used to compare the relative performance of these test kits was also examined. Commercial food products including ice creams, cookies, fried fish sticks, and canned soups were chosen to represent foods that have been pasteurized, baked, fried, and autoclaved, respectively. Calcium caseinate, NIST non-fat dry milk (NFDM) SRM #1549 and USDA certified whey protein were used as reference standards. Veratox and ELISA Systems Casein kits, both of which use NFDM as the calibrator, showed similar readings for ice cream. However, the Casein kit tended to register a lower level of milk residues in other thermal processed products, especially for canned soup where the test kit showed a 50-fold lower level of milk residue than that reported by the Veratox kit. Using whey protein as a reference standard, the two BLG test kits showed a similar level of whey protein equivalent in ice cream, but for fish stick, cookie, and canned soup samples, the x ELISA Systems BLG kit registered values about 4-, 39-, and 17-fold lower than the values obtained by the Biokits BLG test kit, suggesting that the ELISA Systems kit has a greatly reduced sensitivity for foods that have received heat treatments. When using NIST NFDM as the reference standard, the Veratox and Biokits registered the same level of NFDM equivalent in ice cream, but the Biokits gave a higher level for the fish, cookies, and soup samples, indicating that this kit has a better sensitivity for heat processed food. Overall, different test kits registered different levels of milk even for the same commercial sample. The use of common reference materials provides a means for comparison, but the quantitation of milk residues is still complicated by the different heat sensitivity of each test kit. The second part of this study evaluated the impact of thermal processing on the solubility and antigenicity of egg allergens. Solutions (5 mg/ml sample in PBS) of Henningsen dehydrated whole egg, ovalbumin (OVA), and ovomucoid (OVO) were subjected to three different thermal processing conditions (heated in water at 60℃, 100℃, and autoclaved) for 10 minutes. The solubility of the unheated and heat-treated samples was determined by the BCA total protein assay. Changes in the antigenicity (IC50 value) of egg proteins after thermal treatments were determined by inhibition ELISA. Differences in the antigenicity determined as affected by the use of different target protein, coating antigen, and primary antibody were determined. At 60℃, the solubility and antigenicity of heat treated samples showed similar results as those of untreated sample. For sample treated under other conditions, different heat treatments affect the solubility of egg protein samples differently. Different heat processes, different antigen-antibody combinations, and different extraction methods could affect the IC50 values xi differently, which means the antigenicity changed differently due to different influence factors (e.g. IC50 values of OVO always increased after boiling or autoclaving treatment no matter which coating antigen and primary antibody chose, however OVA and whole egg powder showed uncertain changes). The last part of this study evaluated the impact of high pressure processing on the solubility, antigenicity, and the detectability of egg allergens. Solutions of dehydrated whole egg, OVA, OVO, and Egg Beater (ConAgra Foods) were subjected to high pressure treatments for 3 min under 4 conditions (400MPa 20℃, 400MPa 60℃, 600MPa 20℃, and 600MPa 60℃). The amount of protein in the high pressure treated samples was determined by BCA assay and the Veratox egg allergen test kits. Changes in protein antigenicity were determined by inhibition ELISA assay. The results showed that high pressure treatments under all 4 conditions did not affect the solubility and antigenicity of the egg proteins in the treated samples. HPP did not affect the detectability of these proteins by Veratox test either.
M.S. in Food Safety and Technology, December 2013
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Title: COMPUTATIONAL MODELS OF TRANSPARENT WATER STORAGE ENVELOPES FOR ENERGY EFFICIENT COMMERCIAL BUILDINGS
Creator: Liu, Xiangfeng
Date: 2012-04-25, 2012-05
Description: Transparent Water Storage Envelopes (TWSEs) are climatic adaptive fenestration systems. The major part of the system is an array of modular...
Show moreTransparent Water Storage Envelopes (TWSEs) are climatic adaptive fenestration systems. The major part of the system is an array of modular transparent water containers which are integrated into frames of curtain walls, and serve as both façade and auxiliary water tanks for a commercial building. The concept originates from the idea of combing transparency with dynamic benefits of thermal mass in summer, as well as passive solar heating in winter. Optical and thermal characteristics of TWSEs, including their energy performance, have been studied systematically via numerical approaches. Two numerical procedures covered in the thesis: one is based on the simplified synchronized onedimensional nodal thermal model, and the other is based on the more complex and accurate synchronized CFD model. In each numerical procedure, a triple-step simulation methodology and the correlated computational models of TWSEs are employed. Based on the calculation and simulation results, it can be definitely concluded that TWSEs are energy efficient fenestration systems. They can outperform conventional glazing as long as being designed elaborately with the consideration of the unique physical characteristics, applied under suitable climatic conditions, and operated with appropriate energy efficiency measures. Furthermore, the innovative technical paradigm of TWSEs and the numerical approach developed for energy simulation of TWSEs demonstrate great potential to be implemented in engineering practice for energy efficient commercial buildings.
Ph.D. in Architecture, May 2012
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Title: UNDERSTANDING THE MEMBRANE ACTIVITY OF ACYL LYSINE OLIGOMERS
Creator: Lingaraju, Mahesh
Date: 2012-07-10, 2012-07
Description: In the past two decades, Antimicrobial peptides (AMPs) have attracted considerable interest because of their potential therapeutic use as...
Show moreIn the past two decades, Antimicrobial peptides (AMPs) have attracted considerable interest because of their potential therapeutic use as antibiotics, antivirals, and antitumoural drugs. However, there are a number of serious challenges on the way toward bringing AMPs onto the market which include their rapid in vivo degradation, high production costs, reduced activity in physiological conditions, etc. To overcome these problems and yet to capitalize on the immense potential of AMPs, extensive efforts to develop their non-natural mimics have been recently made. A better understanding of the structure-activity relationships of AMPs is essential to the creation of a successful peptidomimetic compound. It has been widely accepted that AMPs kill pathogens by disrupting the cell membrane or invading the cytoplasm and inhibiting core metabolic functions. Thus, the pathogenic membrane plays a crucial role either as an immediate target or as a barrier that must be traversed. Herein, we have investigated the role of charge and hydrophobicity in the interplay between membrane-active molecules (Oligomers of acyl lysine) and model bacterial or host cell membranes using constant-pressure insertion assays, synchrotron X-ray reflectivity (XR) and grazing incident-angle X-ray diffraction (GIXD). The outer surface of a membrane was approximated by a planar lipid monolayer at the air-liquid interface, whose composition was modified in accordance with the cell being modelled. The presented results have helped us to arrive at a general mechanism by which the OAKs seem to interact with lipids which is strongly dependent upon the charge density of the monolayer, charge and hydrophilicity of the molecule and presence of freely accessible hydrophobic regions. The results indicate the molecules fail to interact with the acyl chains when they poorly negotiate with the head group or when they lack accessible hydrophobic regions. Overall, presented results advance current understanding of the mechanism of action of flexible AMP mimics on bacterial membranes and will no doubt aid in the rational design and optimization of non-natural mimics of antimicrobial peptides that will be effective against multidrug resistant bacteria and cancer cells. Nevertheless, future work is required to further understand the critical factors leading to potent anti-infective activity of antimicrobials.
M.S. in Molecular Biochemistry and Biophysics, July 2012
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Title: LIVE LOAD FACTORS FOR CONTINUOUS GIRDER BRIDGES
Creator: Wang, Qing
Date: 2016, 2016-07
Description: Live load factors of Strength I limit state for continuous girder highway bridges are calibrated based on reliability concept adopted by...
Show moreLive load factors of Strength I limit state for continuous girder highway bridges are calibrated based on reliability concept adopted by AASHTO LRFD and LRFR specifications. A uniform reliability is maintained for multi-girder highway bridges with various span lengths. WIM data, gathered by California, Michigan, New York, Oregon, and Illinois State Department of Transportation are analyzed. Live load effects produced by WIM data are calculated using influence lines. Expected maximum live load effects in given periods are modeled and extrapolated by Gumbel distribution. A relativecalibration formula is developed in order to derive live load correction factors for designing/evaluating continuous highway bridges at a reliability level that is in consistent with simply supported highway bridges. Computer programming is conducted for data sorting and traffic statistical analysis.
Ph.D. in Civil Engineering, July 2016
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Title: VALIDATION OF BAKING TO INACTIVATE SALMONELLA IN HIGH-PROTEIN AND HIGH-FAT MODEL FOODS
Creator: Wang, Wenqian
Date: 2017, 2017-07
Description: Baked food products, such as dry pet foods, undergo changes of temperature and water activity (aw) during forced hot air processes. As one of...
Show moreBaked food products, such as dry pet foods, undergo changes of temperature and water activity (aw) during forced hot air processes. As one of the most thermal resistant microorganisms in low-moisture/intermediate moisture foods, Salmonella’s thermal inactivation kinetics during these processes is not well understood and difficult to predict. The objective of this study was to evaluate thermal inactivation kinetics of Salmonella enterica serovar Agona 447967 in model high-protein (HP) and high-fat (HF) multiple-component foods baked in a laboratory-scale oven, as influenced by oven temperature and relative humidity (RH). Model high-protein and high-fat foods, formulated with wheat flour, soy protein and soy oil, were inoculated with Salmonella Agona to a level of ~9 log CFU/g, and mixed to form a homogenous dough. Dough samples (57 mm diameter x 6 mm thick) were baked (3 samples per dwell time, 6 dwell times per condition) in a lab-scale oven at 120°C (10% RH) and 85°C (20%, 35% RH, 50% RH), respectively. Temperature and aw were measured at the surface and geometric center of the product during baking. Processed samples were collected in sterile bags and immediately cooled in an ice-water bath. Salmonella was enumerated on trypticase soy agar supplemented with yeast extract and incubated at 37°C for 24 h. Similar reductions (p>0.05) of 5.12-, 5.11-, 4.55-, and 4.78-log CFU/g were achieved after 40 min at 120°C/10% RH, 90 min at 85°C/20% RH, 50 min at 85°C/35% RH, 8 min at 85°C/50% RH, respectively, in the high-protein model food. Similar results were achieved in the high-fat matrix. The aw at the geometric center of the product (initially at aw =0.98) did not change appreciably during baking, while the aw at the product surface, the location of least lethality, decreased significantly (p<0.05) during baking; the decreases were more pronounced at lower oven RH. The results indicate that thermal inactivation of Salmonella Agona was driven by temperature and relative humidity in the oven. Higher temperature and higher relative humidity level led to greater Salmonella inactivation.
M.S. in Food Process Engineering, July 2017
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Title: THERMAL STABILITY OF FOOD ALLERGENS AND NONALLERGENIC PROTEINS: A COMPARATIVE STUDY
Creator: Wu, Yan
Date: 2015, 2015-07
Description: Thermal stability has been proposed as a criterion to assess the allergenic potential of genetically modified foods, but there is a lack of...
Show moreThermal stability has been proposed as a criterion to assess the allergenic potential of genetically modified foods, but there is a lack of information on the relative thermal stability of food allergens vs. nonallergenic proteins. This study compared the thermal stability of several paired food allergens and nonallergenic proteins by measuring the changes in their solubility, antigenicity and thermodynamic properties after thermal treatment using BCA total protein assay, inhibition ELISA assay, Differential Scanning Calorimetry and Far-UV Circular Dichroism Spectroscopy. The selected protein pairs included bovine α-lactalbumin (allergen) vs. human α-lactalbumin (nonallergen), peanut lectin (allergen) vs. concanavalin A (nonallergen), soybean trypsin inhibitor (allergen) vs. lima bean trypsin inhibitor (nonallergen). With respect to protein solubility, a greater thermal stability was observed for: (1) bovine α-lactalbumin (bovine ALA) when it was autoclaved in water compared with human α-lactalbumin (human ALA) (2) peanut lectin when it was boiled or autoclaved in water compared with concanavalin A (ConA) and (3) soybean trypsin inhibitor (STI) when it was boiled in water or PBS, or autoclaved in water compared with lima bean trypsin inhibitor (LTI). Regarding TM values determined by DSC: (1) bovine ALA was more thermally stable than human ALA under both dry-heat treatment and moist-heat treatment (2) ConA was more thermally stable than peanut lectin during moist-heat treatment, while a greater thermal stability was observed for peanut lectin when the protein was under dry-heat treatment (3) LTI was more thermally stable than STI during heating in water or under dry-heat treatment, while a greater thermal stability was observed for STI when the protein was heated in PBS. Based on CD analyses, (1) bovine ALA was more thermally stable than human ALA (2) peanut lectin was more thermally stable than ConA (3) STI and LTI showed similar thermal stability. With respect to antigenicity, a greater thermal stability was observed for: (1) human ALA when it was autoclaved in water compared with bovine ALA (2) ConA when it was boiled or autoclaved in water, or under dry-heat treatment at 176℃ compared with peanut lectin (3) STI when it was autoclaved in PBS compared with LTI. In summary, allergens tended to be more thermally stable than nonallergenic proteins with respect to solubility, but there was no consistent trend in the relative thermal stability of these protein pairs regarding the antigenicity or the TM values. No correlation between thermal stability of the proteins and their allergenic potential was observed.ConA (3) STI and LTI showed similar thermal stability. With respect to antigenicity, a greater thermal stability was observed for: (1) human ALA when it was autoclaved in water compared with bovine ALA (2) ConA when it was boiled or autoclaved in water, or under dry-heat treatment at 176℃ compared with peanut lectin (3) STI when it was autoclaved in PBS compared with LTI. In summary, allergens tended to be more thermally stable than nonallergenic proteins with respect to solubility, but there was no consistent trend in the relative thermal stability of these protein pairs regarding the antigenicity or the TM values. No correlation between thermal stability of the proteins and their allergenic potential was observed.
M.S. in Food Safety and Technology, July 2015
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Title: EFFECT OF STRAWBERRY ANTIOXIDANTS ON OXIDATIVE STRESS IN INSULIN RESISTANT INDIVIDUALS: A DOSE RESPONSE STUDY
Creator: Vijayakumar, Lakshmi Prabha
Date: 2014, 2014-05
Description: Oxidative and inflammatory stress is associated with chronic disease development and progression. Recent studies suggest that consumption of...
Show moreOxidative and inflammatory stress is associated with chronic disease development and progression. Recent studies suggest that consumption of fruits and vegetables rich in antioxidant compounds attenuate oxidative stress and inflammation. Strawberries are abundant in polyphenolic compounds with antioxidant properties, which have attracted research attention for their possible health benefits. The aim of the project was to determine whether the antioxidant properties of strawberries formulated in a beverage would dose-dependently restore oxidative stress induced by a high fat/ high carbohydrate meal in insulin resistant individuals. Plasma was collected from insulin resistant individuals (n=25) every 30-60 min over 6 h after ingestion after a 650 kcal high fat/ high carbohydrate meal accompanied with a beverage containing 0, 10, 20 or 40 g freeze-dried strawberry powder. The antioxidant capacity of test beverages containing 10, 20 and 40 g strawberry powder were 9.31± 0.66, 19.10 ± 0.60 and 33.57 ± 1.75 μmol Trolox equivalents/mL based on the Oxygen Radical Absorbance Capacity (ORAC) assay. The ORAC value for the placebo (0 g) was below the detectable limits. Biologically relevant oxidative stress was determined using the ORAC assay to estimate antioxidant capacity of the plasma and oxidation of low density lipoprotein (ox-LDL) using an ELISA assay to determine the oxidative damage. Assessment of ox-LDL over 6 hr revealed a significant effect of time (p<0.0001), however no significant difference between the treatment dosages was evident (p>0.05). A marginal treatment by time interaction suggested possible time specific differences between treatments. The evaluation of antioxidant capacity of the plasma was split into assessment of the hydrophilic and lipophilic fractions. Hydrophilic ORAC results showed ix no significant differences between test beverages over 6 hr (p>0.05), including effects of time or treatment by time interactions (p>0.05). The lipophilic ORAC also did not reveal significant differences between treatments (p>0.05). Overall, it appears that beverages with different “doses” of antioxidant capacity did not result in dose-dependent changes in oxidative stress in insulin resistant individuals. There was a trend for protection of ox-LDL by the 20 g strawberry beverage revealed by differences among treatments at 240 min compared to the placebo/0 g strawberry beverage. The findings suggest that antioxidant food properties do not translate directly to plasma antioxidant capacity as measured by ORAC and alternative mechanisms are likely responsible for biological antioxidant effects of strawberry.
M.S. in Mechanical and Aerospace Engineering, May 2014
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Title: A COMPRHENSIVE MECHANISTIC STUDY OF PEPTIDOMIMETICS ON MODEL MEMBRANE SYSTEMS
Creator: Bianchi, Christopher P.
Date: 2014, 2014-12
Description: Peptidomimetics are a broad class of structural variant synthetic mimics of antimicrobial peptides (AMPs). AMPs are natural antibiotics found...
Show morePeptidomimetics are a broad class of structural variant synthetic mimics of antimicrobial peptides (AMPs). AMPs are natural antibiotics found in almost entirety throughout all living organisms. Although, AMPs were once thought of as promising therapeutics to combat infectious bacteria, key shortcomings such as low bioavailability, as well as high manufacturing costs have prevented them from reaching a clinical market. Peptidomimetics capitalize on the characteristics of AMPs thought to be responsible for their antibacterial activity, such as net cationic charge and amphiphilicity, while introducing key structural differences. The principal mode of antibacterial activity of AMPs is causing disruption to the bacteria cell membrane of both Gram-positive and Gram-negative bacteria types. The complexities of cell membranes with their various lipid molecule species and proteins makes it difficult to determine mechanistic details of AMPs. It is for this reason model membrane systems such as Langmuir monolayers and supported bilayers composed of the lipid species found in that of actual cell membrane are used. In the present work we have investigated the mechanism of action of different types of peptidomimetics such as N-substituted glycines (peptoids) and oligomers of acylated-lysines (OAKs) on model bacteria and cancer cell membrane systems using various experimental techniques, such as epifluorescence microscopy (EFM), atomic force microscopy (AFM), X-ray reflectivity, and grazing incidence X-ray diffraction (GIXD). From these studies structure function relationships can be obtained, which help aid in the design of new and more effective peptidomimetics. Through these investigations it was found that the substitution of hydrogen atoms for fluorine atoms in the phenyl side chains of cyclic peptoids increases antibacterial on both Gram-positive and Gram-negative model membrane systems, guanidino containing side chains compared to amino containing side chains in α-peptide-β-peptoid chimeras show greater activity on model membrane systems mimicking the cytoplasmic membrane of both Gram-positive and Gram negative bacteria. In addition, insights were gained on the anticancer mechanisms of the naturally occurring AMP magainin-2 and OAK C12K-7α8. The significance of the model membrane system being used cannot be overstated, when the overall arching goal is to bring these peptidomimetics to a clinical market. Thus, the biological relevance of the model membrane system is of great importance. It is this motivation that has lead our research group to develop a floating planar lipid bilayer that is bound to a lipid monolayer functionalized with polyethylene glycol, which to our knowledge has not been previously done. This system and the planar Langmuir monolayer that were used in this work are ideal systems for the use of high energy X-rays that are produced from synchrotron radiation facilities. From such measurements as X-ray reflectivity (XR) and grazing incidence X-ray diffraction (GIXD) molecular scale resolution of the peptidomimetic interactions with the model membrane systems can be achieved.
Ph.D. in Physics, December 2014
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Title: EVALUATING DYNAMIC JOB PERFORMANCE: A FIELD STUDY OF DYNAMIC PERFORMANCE CHARACTERISTICS AND PERFORMANCE RATINGS
Creator: Hall, Rachael
Date: 2012-12-17, 2012-12
Description: Previous research has established that job performance changes over time, yet the implications of this dynamism for performance evaluations...
Show morePrevious research has established that job performance changes over time, yet the implications of this dynamism for performance evaluations remain unclear. Studies that have examined the implications of different dynamic performance characteristics have mostly been laboratory based and have included a variety of performance measures, except for supervisor ratings of performance. Therefore, the present study integrates and builds on the literature on dynamic performance and performance ratings by examining its effects in an applied setting. Predictions were made about how the patterns in objective performance over a 12-month performance period would relate to annual performance appraisal ratings. Based on the monthly performance of 1,100 troopers working for a state law enforcement agency, main effects were found on supervisor ratings for the mean and trend in objective performance. However, the performance trend unexpectedly had a negative association with performance ratings. An interaction between the performance trend and variability also provided new information about how dynamic performance characteristics may interact to have an influence on ratings. Findings from the current study add to the existing research on dynamic performance characteristics and performance ratings, but more research is needed to understand the implications for different jobs and contexts.
M.S. in in Psychology, December 2012
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