Search results

Title: TRACING TEXTUAL MEDIATING ARTIFACTS AS AGENTS OF CHANGE AND VANGUARDS OF CORPORATE NORMS
Creator: Pappas, George
Date: 2017, 2017-05
Description: Technical communicators often employ user-centered design approaches to design textual artifacts that mediate workplace activity. The artifact...
Show moreTechnical communicators often employ user-centered design approaches to design textual artifacts that mediate workplace activity. The artifact’s designer is positioned as an expert who knows what is best for the artifact’s user (worker). I argue that those methods discount the role of the worker. I apply activity theory as the conceptual framework and genre tracing as the research method to analyze a corpus of documents that mediated the training evaluation activity at ABC Pharmaceutical (a pseudonym for the company’s name) to explain the evolution of those artifacts and theorize the reasons for their historical development. My findings show that their evolution – whether in the form of new genre selections, modifications, splicing, or even abandonment of genres – was influenced by worker efforts that challenged the official expert solutions. The implications of these findings to the fields of technical communication and business research are that even though design experts and business leaders may want to control the organizational strategies, work processes, and mediating artifacts/tools that accomplish those actions, workers will challenge official positions. There are dialectical forces at work that reflect official centripetal efforts that seek organizational stability from formal, normal, and regular structures versus centrifugal efforts that are disruptive and ad hoc in nature. The genre battles Idiscuss in this dissertation reflect a process that should be accepted as healthy and normal by both leadership and design experts, rather than feared or overly regulated.
Ph.D. in Technical Communication, May 2017
Show less

Title: IMPACT OF RELATIONSHIP FUNCTIONING AND PATIENT MOTIVATION ON ADHERENCE AND WEIGHT LOSS AFTER BARIATRIC SURGERY
Creator: Noth, Kathryn
Date: 2013, 2013-07
Description: Background: Bariatric surgery is the most successful intervention to treat severely obese individuals, yet there is significant variability in...
Show moreBackground: Bariatric surgery is the most successful intervention to treat severely obese individuals, yet there is significant variability in surgical outcome (Hsu et al., 1998, Sarwer, Wadden, & Fabricatore, 2005). Success primarily depends on patients’ ability to make and maintain recommended changes to their lifestyle after surgery. Patients’ ability to make and maintain changes to behavior is impacted by elements of the socioenvironmental context. Prior research on a number of different medical populations suggests that an individual’s partner or spouse may facilitate or hinder behavior change (Sher et al, 2011). Study Aim: The current study examined the role of relationship functioning on patients’ motivation for and adherence to health behavior changes and weight loss (%EWL) after bariatric surgery. Based on self-determination theory, it was hypothesized that better relationship functioning, higher levels of autonomous motivation to make lifestyle changes, and less emotional eating (EE) would be associated with better adherence and %EWL after bariatric surgery. Procedure: Participants were 111 women who had undergone a bariatric procedure at least 2 years prior to study participation and who were also in a monogamous relationship for at least six months. Participants completed a series of online questionnaires that assessed relationship functioning, motivation, EE, adherence to recommended changes after surgery, and %EWL. Results: Results indicated that better relationship functioning and higher levels of autonomous motivation were directly associated with better adherence to recommended changes postsurgery. Better adherence to recommended eating behaviors was related to higher %EWL, and both relationship functioning and autonomous motivation were indirectly x associated with %EWL through their impact on eating behavior adherence. Emotional eating was negatively associated with both %EWL and eating behavior adherence. Conclusions: These findings indicate that both individual (motivation, EE) and couples factors (relationship functioning) directly impact patient outcome after bariatric surgery. Clinical application, limitations, and future directions are discussed.
PH.D in Psychology, July 2013
Show less

Title: NOVEL MATERIAL SYNTHESIS THROUGH SOL-GEL AND HYDROTHERMAL METHODS FOR FUNCTIONAL APPLICATIONS
Creator: Wang, Chuanlong
Date: 2014, 2014-05
Description: Novel material synthesis was investigated in this thesis to show two major promising ceramic material Fe-Si-O composites and Na3MnCO3PO4...
Show moreNovel material synthesis was investigated in this thesis to show two major promising ceramic material Fe-Si-O composites and Na3MnCO3PO4 composite. Major processing factors in forming Fe2SiO4=SiO2 and Fe2O3=SiO2 powders via sol-gel synthesis followed by solid-state reactions are investigated. The results clearly indicate that the chemical compositions of the precursors, the ratio of the precursors, the nature of the catalyst used, and the gas atmosphere during solid-state reactions can all a ect the outcome of the reaction product(s). The formation of Fe2SiO4=SiO2 is enhanced by using the precursor iron(III) acetylacetonate as the Fe source with the precursor ratio of iron(III) acetylacetonate to tetraethylorthosilicatebeing 1:1 and the addition of formic acid. Otherwise, crystalline Fe and Fe3C are formed in place of Fe2SiO4. By altering the gas atmosphere during solid-state reactions from argon to oxygen, the reaction products change from Fe2SiO4=SiO2 to Fe2O3=SiO2. All of the observed phenomena can be rationalized via the degree of mixing of the Fe-O and Si-O domains at the molecular level in the gel network during sol-gel reactions and the presence of a reducing or oxidizing atmosphere during the solid-state reaction. Hydrothermal method was applied in synthesizing Na3MnCO3PO4 composite which was studied as a high energy density material for Na ion battery (NIBs). In order to improve electronic conductivity for NIBs battery, ball milling with graphite was introduced for the as-synthesized material. This thesis will investigate the roles played by the ionic conductivities and crystal structure changes introduced by high energy ball milling. Such a study has never been conducted before, and thus can o er guidelines to unlock a gateway to truly low cost Na3MnCO3PO4 cathode NIBs with superior performance.
M.S. in Materials Engineering, May 2014
Show less

Title: INVERSE MINIEMULSION POLYMERIZATION OF PHOSPHATE-LOADED HYDROGEL NANOPARTICLES FOR SEPSIS PREVENTION
Creator: Vadlamudi, Srivishnu
Date: 2014, 2014-05
Description: Drug delivery is an exciting field of interdisciplinary research that has captured the interests of the Pharmaceutical and Biotechnology...
Show moreDrug delivery is an exciting field of interdisciplinary research that has captured the interests of the Pharmaceutical and Biotechnology industry. With the continual advances in discovery and synthesis of effective drugs, it is imperative to create safe and efficient drug-delivery systems. Biocompatible polymer nanoparticles are beginning to provide innovative solutions and form the frontier of advanced drug-delivery technology and Nanomedicine. Phosphate ions have been identified to be instrumental in healing wounds and preventing post-surgery gut-derived sepsis. We have developed a process of inverse miniemulsion polymerization to produce highly crosslinked, Biocompatible PEG diacrylate nanoparticles in the size range of 156-217 nm encapsulated with comprising phosphate ions. An aqueous solution containing high amounts of crosslinker (PEG diacrylate 575), NVP, phosphate salt and a water-soluble thermal initiator was emulsified in cyclohexane (oil-phase) by the application of high shear (ultrasound) to generate an inverse miniemulsion. The aqueous nano-droplets were stabilized against coalescence by the use for two non-ionic surfactants. The presence of phosphate salt within these stable nano-droplets prevented destabilization of the miniemulsion against Ostwald ripening. The encapsulation of phosphate within the nanoparticles is made certain by selecting a phosphate concentration dictated by the PEGDA-Phosphate temperature-dependent thermodynamics. Reported experimental measurements include monomer conversion, particle size measurement and aqueous swelling characteristics. Nanoparticle tracking Analysis (NTA) methodology developed by Nanosight Inc. was used for particle size measurements. A factorial design of experimentation coupled with the application of a xiii kinetic model indicate a low range (10-3 – 10-4) of the initiator efficiency in the reaction kinetics. The comparison of experimental conversion data with model predictions, points towards a well documented notion of a drastic reduction in initiator efficiency that once a critical degree of crosslinking is achieved within the nanoparticles during the reaction. The inverse swelling ratios (proportional to crosslink density) of the nanoparticles tend to substantiate the above kinetic behavior. The preliminary medical testing of the synthesized nanoparticles showed promising results indicating the efficacy of this strategy in drug delivery and regenerative tissue engineering.
M.S. in Chemical Engineering, May 2014
Show less

Title: SYSTEM-ON-CHIP FOR RESEARCH IN ULTRASOUNIC SIGNAL PROCESSING AND IMAGING APPLICATIONS
Creator: Gilliland, Spenser
Date: 2012-05-04, 2012-05
Description: The Ultrasonic Signal Processing System-On-Chip (USPS) provides real-time signal analysis and image processing for the full range of...
Show moreThe Ultrasonic Signal Processing System-On-Chip (USPS) provides real-time signal analysis and image processing for the full range of ultrasound from 20 KHz to 20 MHz. The project aims to make it simple to effectively develop and implement algorithms in embedded software and reconfigurable hardware. This provides the user with an opportunity to explore the full design space including software only, hardware only, and hardware/software co-design. The USPS system provides high speed access to a 12-bit 250 MSPS Maxim MAX1215N ADC controlled by a Xilinx XC5VLX110T FPGA. Access to the ultrasound data and custom coprocessor cores is available through a gigabit Ethernet connection managed by an embedded Linux based operating system running on a Microblaze processor instantiated in the FPGA fabric.
M.S. in Computer Engineering, May 2012
Show less

Title: CHARACTERIZATION OF CELL SURFACE PROPERTIES, CHLORINE RESISTANCE AND SURVIVAL OF ESCHERICHIA COLI O157:H7 STRAINS
Creator: Depa, Keshava Reddy
Date: 2011-11-28, 2011-12
Description: Escherichia coli O157:H7 outbreaks linked to tainted fresh produce have increased during recent years. The aim of this study is to...
Show moreEscherichia coli O157:H7 outbreaks linked to tainted fresh produce have increased during recent years. The aim of this study is to characterize the cell surface properties, chlorine resistance and attachment to leafy greens of several E. coli O157:H7 strains belonging to different phylogenetic clades, in order to reveal if there is any correlation between their survival and bacterial cell surface properties. Six strains chosen among the nine E. coli O157:H7 clades included the fresh produce outbreak associated strains Sakai (1996 sprout outbreak in Japan) and TW14359 (2006 spinach outbreak in the US). The growth kinetics of these strains was compared in BHI broth containing 0.81 ppm free chlorine. Cell surface hydrophobicity, auto-aggregation and curli production were determined by in vitro assays and compared to the generic E. coli strain BW25113. The results showed that these E. coli O157:H7 strains exhibited different chlorine resistances regardless of their phylogenetic distance. They were approximately 20% more hydrophilic (p=0.0072) and showed 77% less auto-aggregated cells (p=0.049) after overnight incubation in broth than the generic E. coli strain. However, no distinguishable hydrophobic or aggregation properties were observed among the six E. coli O157:H7 strains despite their different resistances toward chlorine treatment. Curli production measured by a Congo-Red binding assay in suspension varied among the strains and exhibited no correlation with chlorine resistance. In preliminary studies of chlorine exposure (0.81 ppm) of cells being attached to spinach leaf surface, the spinach outbreak strain TW14359 showed less inactivation (2.6-fold) than the sprout outbreak strain Sakai (15-fold). The information generated from this study will help to develop more effective interventions used in the produce industry.
M.S. in Food Safety and Technology, December 2011
Show less

Title: SECURITY POLICY MANAGEMENT, THREAT ALLEVIATION AND TRUSTED PLATFORMS FOR EMBEDDED COMPUTING SYSTEMS
Creator: Anand, Vijay
Date: 2011-08, 2011-07
Description: Security guarantees are a measure of trust that can be placed on computing services in the safeguarding of digital assets. These security...
Show moreSecurity guarantees are a measure of trust that can be placed on computing services in the safeguarding of digital assets. These security goals and guarantees coupled with known and modeled threats to the digital assets shape the security policies for computing services. The creation, management and implementation of security policies in computing services is a challenge in defining the role of policy, the management principle for decision making when posed with threats and overall control over digital assets in a well-defined manner. In this Ph.D. thesis we establish a causal relationship of security policies with threats, provide an industry standard management framework (Six Sigma) for decision making, changes to the constructs of the trusted platform module to create a control framework and, finally show how the security framework can be used in a commercial service. The process of updating and refactoring security policy changes becomes a time consuming and tedious task, especially when threats evolve and computing service constructs change when security policy implementations are implicitly implemented. With the basis of correlation of policies over threats an explicit security policy implementation is proposed such that its adaptability, testability and risk quantification can be achieved when threats evolve. In this study we explore policy threat correlation on a Trusted Platform Module (TPM), a hardware system entrusted with security operations and guarantees. An effective TPM needs to adapt to evolving threats arising from firmware bugs or decay in the complexity of ciphering algorithms. Therefore, an adaptive TPM architecture is proposed to counter evolving threats by integrating an FPGA (Field Programmable Gate xi Arrays) block to alter and patch firmware and change ciphering systems. We present how security guarantees in an IT(Information Technology) infrastructure can be met using a TPM and thereby should be an integral part of computing services along with other security constructs like firewalls, intrusion detection systems, anti-virus, etc.. Adaptive security policy requires a management process wherein the risk management, and cost effectiveness principles can be identified. This is essential to make decisions on the trust criteria of digital assets in an industrial management framework. The security policy creation and management process presented in this thesis is based on Six Sigma model and presents a method to adapt security goals and risk management in an industrial framework. As an effective implementation of the security policy the case of application commerce workflow for developers is presented. Secure application distribution and execution guarantees lie in the transfer of trust between various processes in a computing service, also known as Chain of Trust in an embedded system. This study presents application development workflows facilitating secure commerce of digital assets thereby improving consumer trust.
Ph.D. in Computer Engineering, July 2011
Show less

Title: SHORT AND ULTRASHORT-PULSED LASER-MATERIAL INTERACTIONS: MODELING AND COMPARISONS WITH EXPERIMENTS
Creator: Tao, Sha
Date: 2013, 2013-07
Description: Lasers have wide applications in numerous areas. Laser-based applications and technologies often involve certain types of laser-material...
Show moreLasers have wide applications in numerous areas. Laser-based applications and technologies often involve certain types of laser-material interactions, many of which have not been sufficiently understood. In this thesis, through the development of the corresponding physics-based models and the comparisons of modeling results with relevant experiments (when available), the laser-material interaction mechanisms during the following processes will be studied: i) laser ablation of semiconductors; ii) laser-material interactions inside microholes; and iii) laser-induced plasma evolution (more detailed conditions of the studied processes are given in the thesis). This research work is expected to improve the understanding of laser-material interaction mechanisms in the above investigated processes, which may provide information that is useful for the improvement of many related existing laser-based applications or technologies and for the development of novel ones.
PH.D in Mechanical and Aerospace Engineering, July 2013
Show less

Title: MODELING, ANALYSIS AND CONTROL OF COMPLEX ADAPTIVE SYSTEMS
Creator: Ozturk, Mustafa Cagdas
Date: 2015, 2015-07
Description: A comprehensive approach to the incorporation of adaptive behavior into complex systems is provided through attentive combination of a wide...
Show moreA comprehensive approach to the incorporation of adaptive behavior into complex systems is provided through attentive combination of a wide variety of methods from di↵erent fields. Two examples of complex systems were subjected to this approach, which involves modeling, analysis and control of the processes. The first system of interest is an autocatalytic reactor with multiple resources and multiple species. A continuous stirred-tank reactor model was developed, and subsequently analyzed using bifurcation analyses. The multiplicity character of the system was investigated, and emergent features, such as stable coexistence of autocatalysts, were discovered. Next, an agent-based control system was implemented on the process model using finite-state machines with simple rules as local control elements. The control system is capable of transitioning the process between the numerous steady states evidenced by the bifurcation analysis, as well as exploring the state space for a feasible steady state, given arbitrary set points for the autocatalysts. Eventually, Equation-Free coarse graining methods were applied to this model to investigate the local stability of the agent-controlled system. It was shown that this approach indeed was able predict the correct stability behavior for a given steady state, using only input-output information from short simulations with the closed-loop system. The second system considered was the activated sludge process, which was modeled based on data from an existing wastewater treatment plant. This realistic and complex model was then subjected to in-depth bifurcation analyses using various model parameters. The bifurcation analyses revealed many interesting phenomena about the process, including steady state multiplicity and conditional stability. In addition, potential risks of operation under certain conditions, such as the loss of biomass, were outlined. Furthermore, the aeration requirement of the process was investigated and the possibility for 55% savings in aeration with the same e✏uent quality was illustrated. Finally, in order to enhance the potential of savings in aeration, an agentbased control system was implemented on the activated sludge process. This control system optimized the local airflow rates in real time, and provided a decrease of up to 65% in the aeration rate. In addition, the process was shown to endure severe storm events and aeration failures thanks to the adaptive features of the agent-based control system.
Ph.D. in Chemical Engineering, July 2015
Show less

Title: ANISOTROPIC MICROSRHEOLOGY OF SELF-ASSEMBLING COLLAGEN NETWORKS
Creator: Dutov, Pavel
Date: 2015, 2015-05
Description: Collagen is the main component of human connective tissue and extracellular matrix. Here we report multiple novel methods for utilizing...
Show moreCollagen is the main component of human connective tissue and extracellular matrix. Here we report multiple novel methods for utilizing optical tweezers to measure mechanical properties of different hierarchical levels of collagenous materials. First, we introduce a method for optical trap calibration that is suitable for viscoelastic material. The method is designed for use on experimental setups with two optical tweezers and is based on pulling a trapped particle with one trap while holding it with the other. The method combines advantages of commonly known PSD-fitting and fast-sweeping methods, allowing calibration of a completely fixed trap in a fluid of unknown viscosity/viscoelasticity without additional expensive equipment. Then we report an approach to measure the longitudinal component of the elastic moduli of biological fibers under conditions close to those found in vivo and apply it to type I collagen from rat tail tendon. This approach combines optical tweezers, atomic force microscopy, and exploits Euler-Bernoulli elasticity theory for data analysis. The approach also avoids the traditional drying-soaking cycle, since samples are freshly extracted. Importantly, strains are kept below 0.5%, which appear consistent with the linear elastic regime. We find, surprisingly, that the longitudinal elastic modulus of type I collagen cannot be represented by a single quantity but rather is a distribution that is broader than the uncertainty of our experimental technique. Lastly, we report a new method for characterizing anisotropic viscoelastic response of collagenous matrices. Anisotropic collagenous extracellular matrices are used in biomedicine to enhance the wound healing process by directing fibroblast proliferation. We utilize an optical trap to monitor the thermal fluctuations of microspheres embedded into collagenous network to extract a viscoelastic response function of the network along the principal axes of anisotropy.
Ph.D. in Chemical Engineering, May 2015
Show less

Title: Development of Granular Jamming Soft Robots from Boundary Constrained to Interconnected Systems
Creator: Tanaka, Koki
Date: 2023
Description: This dissertation provides a detailed study on the conceptualization, creation, and optimization of a unique, interconnected soft robot system...
Show moreThis dissertation provides a detailed study on the conceptualization, creation, and optimization of a unique, interconnected soft robot system. It introduces a flexible assembly of locomotive robotic modules interconnected by an envelope, capable of granular jamming. In doing so, it highlights the practical capabilities of these interconnected modules to adapt and function cohesively as a single robot system.As a precursor to the primary investigation, the study initially presents the development and experimental validation of a boundary constrained mobile soft robot. This design leverages granular jamming for locomotion and object grasping, thereby laying a robust foundation for the subsequent exploration of complex soft robotic systems.The cornerstone of this study is the development of an interconnected soft robot system, where locomotive robotic modules, primarily composed of an elastic material, are bound together by a flexible envelope designed for granular jamming. The robotic modules, fundamentally constructed from an elastic material, incorporate origami-inspired artificial muscle actuators. These actuators, with their semi-soft characteristics, complement the inherent flexibility of the modules and play a significant role in facilitating module propulsion. Although the design incorporates a traditional rigid power source, as opposed to a fully soft robot system, the integration of a pneumatic power method into the system successfully reduces the mechanical intricacy and unwieldiness typically associated with rigid mechanisms.This research further probes into the diverse applications of this interconnected soft robot system. Its ability to shape-shift and maintain these forms during locomotion exemplifies a robust control strategy for the system that may undergo substantial deformation, proving instrumental in dynamic environments. The study demonstrates a methodology for object manipulation and obstacle avoidance that does not rely heavily on precise control and sensing. Instead, it utilizes the inherent compliance of the soft robot system. In a notable departure from previous studies, the system also exhibits a unique capability for ascending and traversing inclined surfaces.Additionally, the study dives into the optimization of the interconnected robot system via a physics-based simulation and genetic algorithm. This approach results in an assortment of optimized configurations that excel in object grasping tasks of various shapes, thereby laying a robust groundwork for the progression of soft robotics in the future.In conclusion, this investigation reveals groundbreaking insights into the field of soft robotics through the successful design and optimization of an interconnected soft robot system. Its standout performances in deformation, manipulation, and navigation tasks set it apart. This work serves to significantly enhance the adaptability and functionality of future robotic systems, pushing the edge of what is possible across a diverse range of sectors. By portraying a significant step towards a future where robots can dynamically adapt to their environments and efficiently accomplish complex tasks, this dissertation exemplifies a transformative stride in the field.
Show less

Title: Efficacy and Mechanisms of Power Ultrasound-Based Hurdle Technology for Reduction of Pathogens in Fresh Produce
Creator: Zhou, Xinyi
Date: 2023
Description: Minimally processed produce is frequently contaminated with foodborne bacterial pathogens. Power ultrasound is a non-thermal and cost...
Show moreMinimally processed produce is frequently contaminated with foodborne bacterial pathogens. Power ultrasound is a non-thermal and cost-effective technology that can be combined with other chemical sanitization methods. This study investigated the reduction of Listeria monocytogenes and Salmonella Newport on grape tomato, romaine lettuce, and spinach washed with water, chlorine, or peroxyacetic acid alone or in combination with 25 or 40 kHz power ultrasound for 1, 2, or 5 min. Produce items were inoculated with selected pathogens at approximately 10 log CFU/g, air dried for 2 h, and then treated. Combined treatment of ultrasound and sanitizers resulted in 1.44-3.99 log CFU/g reduction of L. monocytogenes and 1.35-3.62 log CFU/g reduction of S. Newport on washed produce items, with significantly higher reductions observed on grape tomato. Synergistic effects were achieved with the combined treatment of power ultrasound coupled with the chemical sanitizers when compared to the single treatments. An additional 0.48-1.40 log CFU/g reduction of S. Newport was obtained with the combined treatment on grape tomato. In general, no significant differences (p<0.05) were observed in pathogen reductions between the selected ultrasound frequencies, sanitizers, or treatment lengths. Results from this study suggest that incorporation of power ultrasound to current treatment can enhance bacterial pathogen reduction on fresh produce surface, but cannot completely eliminate bacterial pathogens. Transcriptomic study revealed significant (|Log2 fold change|<1 and false discovery rate < 0.05) transcriptional changes in L. monocytogenes LS810 in response to the 2 min power ultrasound treatment. The up-regulation of genes encoding TPI, LLO, and PTS indicates increased energy requirements, enhanced virulence, and demand for sugar sources in bacteria. On the other hand, the down-regulation of genes involved in cyclic dimeric GMP hydrolysis and transcriptional regulation suggests a modulation of intracellular signaling, cellular processes, and metabolisms to enhance survival and recovery. The GO and KEGG analysis demonstrated defense mechanisms against ultrasound stress more comprehensively. L. monocytogenes adjusts its metabolism, repairs cell membranes, and conserves energy for survival. These findings enhance our understanding of its adaptation to environmental stress. Results of this study can be used as a start point for optimizing the efficacy of ultrasound-based hurdle treatments for fresh produce disinfection.
Show less

Title: Three Essays on the Internet Economy
Creator: Sun, Yidan
Date: 2024
Description: In an era of digital platforms, the integrity and visibility of consumer reviews, the dynamics of digital advertising markets, and the role of...
Show moreIn an era of digital platforms, the integrity and visibility of consumer reviews, the dynamics of digital advertising markets, and the role of software development kits (SDKs) emerge as pivotal elements shaping user experiences and platform economics. My research spans three distinct but interconnected domains: the impact of safety reviews on Airbnb, the effects of privacy protections on digital advertising markets, and the significance of SDK releases in the evolution of Apple's iOS app market. We find that critical reviews concerning the safety of an Airbnb listing's vicinity influence guest bookings negatively and, therefore, could boost platform revenues if such reviews were obscured, highlighting a misalignment between consumer interests and platform revenue objectives. This effect is more pronounced in low-income and minority neighborhoods, suggesting a nuanced impact on different community segments. In the digital advertising sector, we identify that data frictions disproportionately harm small publishers, especially when associated with smaller ad intermediaries, underscoring the vulnerability of niche players to market and regulatory changes. Lastly, our analysis of the iOS app market reveals the instrumental role of SDK releases in fostering the app ecosystem's growth, independent of the expanding iPhone user base. Together, these findings underscore the complex interplay between consumer feedback, technological advancements, and market dynamics in digital environments, urging a balanced approach that safeguards consumer interests while fostering innovation and equitable market practices.
Show less

Title: Nanopore sensing for environmental and biomarker analysis
Creator: Arora, Pearl
Date: 2024
Description: Nanopore stochastic sensing is a powerful analytical tool for detecting target molecules through a nanoscale pore. The analyte and electrolyte...
Show moreNanopore stochastic sensing is a powerful analytical tool for detecting target molecules through a nanoscale pore. The analyte and electrolyte ions are subjected to a voltage bias which drives them to translocate through the nanopore, resulting in disruptions in the ionic current. These disruptions are translated to blockage events which can serve as a signature of the analyte. Owing to its unique features of single-molecule and label-free sensing, nanopore technique has been exploited in a wide array of applications such as detection of metal ions, proteins, DNA, microRNA, toxic agents etc. In this dissertation, projects showcasing nanopore’s sensing capability of different biomarkers and in the detection of a wide range of target molecules based on non-covalent interactions are presented. Particularly in the first two projects, nanopore detection of ferric ions relevant to environmental regulation as well as a biomarker for human health and a miRNA-based biomarker for oral cancer and oral related diseases are summarized. Ferric ions, which are benign if present in balanced quantities but can be toxic otherwise, are detected by using an engineered multifunctional nanopore and a chelating organophosphonic acid ligand. The chelate complex formed after ferric ions bind to ligand gives significantly different event signatures than the free ligand in the solution enabling ferric ion detection. Even in the presence of interfering ions, the ferric ions could be recognized easily because of the conformational changes brought in the nanopore lumen by the interaction of the interfering metal ions with the His-tags of the nanopore which in turn resulted in variations in the characteristics of blocking events. In the second project, miR31, an oral cancer biomarker, is selectively detected with the help of an engineered nanopore, and a DNA based probe. Several probes with variations in length, composition and position of the overhangs or probes with no overhangs were compared and studied as the probes play a crucial role in capturing the target of interest with high specificity. Our strategically designed probe emerged as the most effective in capturing the target even in presence of large background from human saliva samples and enhanced the sensitivity of the system. In the first two projects, nanopores are utilized for selective and specific detection of certain target molecules. However, in order to analyze diverse range of analytes, numerous sensing systems have to be constructed which can be a time-consuming and challenging task. To circumvent this limitation, in the third project, diverse recognition sites based on various non-covalent interactions are incorporated into the α-hemolysin protein pore to achieve detection of not just a single analyte but broad category of molecules such as cations, anions, aromatic and hydrophobic compounds.
Show less

Title: Evaluating antimicrobial efficacy of GS-2 on reusable food packaging materials
Creator: Birje, Nupoor Prasad
Date: 2024
Description: Packaging plays an important role in maintaining the quality and safety of fresh produce throughout storage, transportation and end-use by...
Show morePackaging plays an important role in maintaining the quality and safety of fresh produce throughout storage, transportation and end-use by consumers. Single-use packaging poses several environmental impacts; therefore use of reusable packaging is being encouraged in the fresh produce supply chain. However, the utilization of harmful chemicals and inadequate sanitation standards limit the reuse of packaging materials. To overcome these limitations, this study focuses on testing a non-toxic, water-soluble antimicrobial; GS-2 coating to facilitate the reuse of food packaging and reduce the risk of microbial contamination. In this study, the antimicrobial activity of GS-2 was evaluated against foodborne pathogens; Escherichia coli, Listeria monocytogenes and Salmonella enterica on plastic and cardboard coupons at 1 h and 15 min treatment times and 0.3%, 1% and 3% concentration. These coupons were also stored at 4℃ and 90% R.H. and 18℃ and 45% R.H. inoculated on different days up to 42 d with E. coli or L. monocytogenes to study retention of activity of GS-2. Additionally, the efficacy of GS-2 to reduce transfer of bacteria from cardboard and plastic to tomato was investigated. The initial level of inoculum was 9 log CFU/surface for all experiments. Cardboard and plastic without GS-2 were used to compare the reduction of bacteria on the treated surfaces. The differences in the population of bacteria were evaluated using Student’s T-Test and ANOVA; p <0.05 was considered significant. With 3% GS-2 concentration on plastic, there was > 4.50 log CFU/surface reduction of all three bacteria in 1 h. There was a lower reduction of the population on cardboard as compared to plastic for all bacteria, the reduction obtained was 1.83, 2.65 and 3.42 log CFU/surface for E. coli, L. monocytogenes and S. enterica, respectively, in 1 h. There was no significant difference between 15 min and 1 h treatments for cardboard. Further, the highest reduction of bacteria was obtained with 3% GS-2 on plastic. For cardboard, no significant difference in population reduction was obtained for E. coli or S. enterica, with 1% or 3% GS-2. However, for L. monocytogenes there was a higher reduction with 3%. GS-2 remained active on the surface of plastic and cardboard for a period of six weeks. For cardboard, there was a lower reduction of bacteria and there was no trend in the population reduction from 0 to 42 d, with the populations remaining within a range of 4-5 log CFU/surface. There was a significant transfer of E. coli or L. monocytogenes from plastic surfaces without GS-2 to tomato at 5-6 log CFU/tomato. However, the transfer of bacteria from the GS-2-coated plastic to the tomato was below the limit of enumeration. For cardboard, the population was below the limit of enumeration, irrespective of the GS-2 coating. Based on the results, GS-2 is a promising antimicrobial that reduces the microbial load on packaging surfaces and prevents cross-contamination of fresh produce. The retention of GS-2 activity makes it suitable for reusable packaging applications.
Show less

Title: Capital Design: The Role of Design in Institutional Capital Allocation
Creator: Ostapchuk, Jordan
Date: 2024
Description: There is a paradox within the $100 trillion institutional investment industry: the more choices an institutional investor has, the more...
Show moreThere is a paradox within the $100 trillion institutional investment industry: the more choices an institutional investor has, the more challenging it becomes to make investment decisions. This paradox is significant because capital is one of the most transformational elements of the 21st century, driven by financialization, universal ownership, and increasing systemic risks. The direction of capital flows significantly influences the approach to addressing climate change, aging populations, and the transition to sustainable energy, in addition to supporting the essential physical and social infrastructure supported by institutional capital. This research proposes and substantiates a novel hypothesis: design can significantly influence capital allocation in institutional investment contexts. Through an institutional case study, expert interviews, workshops with master’s level design students, and systems-informed reflective practice, this research identifies asset classes as an important and changeable lens through which institutions engage with the future. It explores how these asset classes shape choices in the capital allocation process and identifies eight design capabilities particularly suited for institutional investment contexts. In doing so, it introduces a framework termed Capital Design. This framework illustrates how design can influence institutional capital allocation by integrating these design capabilities with investment tools through informational lenses within a choice/knowledge map. As a result, Capital Design offers an innovative approach for investors and investees to reorient toward emergent asset categories that directly meet the most urgent societal needs.
Show less

Title: Evaluation of the Native Microbiota and Comparative Analysis of a Known Cronobacter Sakazakii and a Newly Isolated Bacillus Cereus Strain in Powdered Infant Formula
Creator: Patil, Sonali Prashant
Date: 2024
Description: There have been numerous reports of Powdered Infant Formula (PIF) recalls and outbreaks due to the absence of a kill step in the post...
Show moreThere have been numerous reports of Powdered Infant Formula (PIF) recalls and outbreaks due to the absence of a kill step in the post-pasteurization processing, improper handling pre and post processing and/or reconstitution, and lack of effective sanitization and cleaning of the food contact surfaces in the manufacturing facilities. The objectives of this present study were to 1) survey and identify background microflora in commercial PIF products through microbiological analysis, 16S rRNA, and whole genome sequencing (WGS); 2) compare the survival rate of a known Cronobacter sakazakii and a newly isolated Bacillus cereus DFPST-SP1 in PIF under a humidity level of 33 ± 3% over a period of 28 d; 3) examine the relative resistance of these two strains to thermal treatments at temperatures 40, 70, and 100 °C followed by storage at room temperature (RT) for 30 min; and 4) evaluate the bactericidal effect of 70% ethanol on the two artificially deposited bacterial strains on stainless steel (SS) and plastic coupons. Three biological trials were conducted for each study. To determine whether the increase, decrease, or difference in the bacterial populations and other parameters like water activity (aw) was statistically significant, a T-test was performed (p ≤ 0.05 was considered significant). Results of 16S rRNA sequencing revealed the presence of certain bacterial species in PIF, such as Lactococcus lactis, B. cereus, Listeria monocytogenes, Staphylococcus aureus, Salmonella enterica, etc. distributed across a relative abundance of >25%, <25%, and ≤3%. After the enrichment and isolation as per Bacteriological Analytical Manual (BAM), C. sakazakii or S. enterica were not detected, while colonies exhibiting a blue-green appearance resembling Listeria spp. and certain Bacillus spp. were subjected to WGS for species-level identification. The assembly_1 from formulation 1 was confirmed as B. cereus sequence type 2255 and was renamed as B. cereus DFPST-SP1 in the contribution of this thesis work. The storage study conducted on PIF inoculated with C. sakazakii and B. cereus DFPST-SP1 at 33% RH showed that there was 0.25-0.27 log CFU/g reduction towards the end of 28 d, but no significant difference was observed between the two strains. The thermal challenge study revealed that the newly isolated B. cereus strain and C. sakazakii used in this study were highly thermotolerant. Based on the sanitizer challenge study, 70% ethanol was significantly more effective in reducing populations of C. sakazakii as compared to B. cereus. Moreover, higher log reductions of C. sakazakii 587 populations on stainless steel coupons compared to plastic coupons were observed, indicating that bacteria adhere more tightly to plastic surfaces than stainless steel (SS). Overall, the findings of this study shed new light on bolstering the safety standards of PIF and highlight the need for improved cleaning and sanitization procedures within manufacturing facilities in order to ensure the safety of reconstituted PIF, thereby enhancing public health, particularly infants and neonates.
Show less

Title: Ultrasound Image Guided Robot Arm for Targeted Delivery of Therapeutic Drugs and MicroRNA for Cancer Therapy
Creator: Nagarajan Parimala, Abishek
Date: 2024
Description: Molecular imaging has revolutionized medical diagnostics by providing detailed insights into biological processes at the molecular level...
Show moreMolecular imaging has revolutionized medical diagnostics by providing detailed insights into biological processes at the molecular level within the living subject. Ultrasound Molecular Imaging (USMI) has emerged as a promising diagnostic imaging modality by utilizing targeted contrast agents to unveil crucial molecular information, including vascular biomarkers associated with cancer and other diseases. Despite its potential, the transition of Ultrasound Contrast Agents (UCA) from preclinical evaluation to FDA-approved clinical use faces challenges due to the short in vivo half-life of Micro-Bubbles (MBs), necessitating repeated administrations for comprehensive assessments. Moreover, conventional ultrasound imaging methods suffer from limited scanning areas and single-target focus, leading to low throughput in preclinical evaluations.This thesis addresses these challenges by proposing a robot-assisted whole-body scanning pipeline for preclinical evaluations in Ultrasound Molecular Imaging. By integrating a robotic arm into the imaging setup, this approach enhances scanning flexibility and precision, enabling scans across the entire body of a mouse. This extension of the imaging time window allows for comprehensive assessments without the need for repeated contrast agent administrations. Additionally, the ability to simultaneously scan multiple targets within the same session significantly increases the throughput of preclinical assessments, thereby improving the efficiency and reliability of Ultrasound Molecular Imaging in clinical translation.
Show less

Title: Effect of Stress Triaxiality and Lode Angle on Ductile Fracture
Creator: Nia, Mahan
Date: 2023
Description: Although many ductile damage accumulation studies have been done in recent years, there is still insufficient research towards the development...
Show moreAlthough many ductile damage accumulation studies have been done in recent years, there is still insufficient research towards the development of ductile fracture models, mainly due to the difficulty of performing experiments under different states of multiaxial stress. The goals of this Ph.D. research are to (i) produce much-needed experimental data, (ii) investigate the performance of existing models against these data, and (iii) develop a new predictive ductile fracture model validated by experiments. The new model seeks to predict the fracture strain as a function of the stress triaxiality and normalized Lode angle. One of the prominent works in this area was done by Bai and Wierzbicki in 2008 by testing 2024-T351 aluminum alloy. They proposed an asymmetric 3D empirical fracture model with six model parameters. Thus, the Bai method was investigated alongside a new model for predicting ductile fracture. For that purpose, 2139-T8 aluminum alloy was chosen for our experimental program to evaluate these models better, and the data extracted from Bai's work was also used as an additional data set. An extensive experimental program was considered to create different stress states in the material, including tensile tests (with round smooth and four round notched and plate specimens), torsion, compression (with four smooth and two notched specimens), and shear-compression experiments (two different sizes). The specimens were longitudinally machined from a block of 2139-T8 aluminum alloy. The combined effects of two variables, stress triaxiality and normalized Lode angle, define a 3D fracture envelope for fracture strain. A parallel FE simulation (fine-tuned by the experimental results) has been performed for each experiment to evaluate the evolution of stress triaxiality and Lode angle in the gauge section of the specimens with complicated geometries. Finally, these results were used in developing two predictive fracture models. The first model is based on the Bai-Wierzbicki form of fracture. The second one is a new model that has been presented in this research. This new model is a modification of the Johnson-Cook fracture model and considers the simultaneous effects of Lode angle and stress triaxiality in fracture. The original Johnson-Cook fracture model (1984) does not consider the Lode angle effect. In the end, errors in the proposed approach to modeling ductile fracture have been compared to errors from Bai's work, resulting in the conclusions and recommendations for future studies.
Show less

Title: Two Essays on Mergers and Acquisitions
Creator: Xu, Yang
Date: 2024
Description: This dissertation is composed of two self-contained chapters that both relate to mergers and acquisitions (M&A). In the first essay, we...
Show moreThis dissertation is composed of two self-contained chapters that both relate to mergers and acquisitions (M&A). In the first essay, we examine the Delaware (DE) reincorporation effect on firms’ post-IPO behaviors on mergers and acquisitions. We find that firms’ DE reincorporation decisions enhance the likelihood of engaging in M&A as targets. However, as a tradeoff, DE reincorporated firms get lower takeover valuations compared to stay-at-home-state firms, and the acquisition of reincorporated firms is less likely to be successful. Our second essay aims to explore the role of the options market in price discovery for M&A. We find that the predictive power of the changes in implied volatility of the target firm stock for the takeover outcome is statistically and economically significant. The risk arbitrage portfolios incorporating filters derived from the options on stocks of the target firms generate annualized risk-adjusted abnormal returns between 2.6% and 5%, depending on the portfolio weighting method, the threshold of filters for the implied volatility change, and the asset pricing models applied for abnormal returns. The results are robust to different empirical setups and are not explained by traditional factors.
Show less

repository.iit

Search the repository

Pages

Pages