bluuebunny/crossref_metadata_2025 huggingface dataset:
Electrospinning fluorescent hybrid polyelectrolyte ultra-fine fibers
Authors:   , Atchison Jennifer S. , Schauer Caroline L.
Published: July 2021

Nanofibers, by virtue of their extremely large surface area to volume ratio, promise to be an excellent platform to explore interactions of small volumes of analytes with the nanofiber-nanoparticle composite. Electrospinning is a facile nanofabrication technique that produces fibrous assemblies of ultra-fine fibers, 20-1000 nm in diameter, from a charged droplet of spinning solution. Optimization of the fiber diameter of a specific material system is dependent on the solution and process variables. Specifically we have established the electrospinning parameters for poly (acrylic acid) (PAA), chitosan in formic acid, polyelectrolyte complexes, and composites of these with quantum dots. The composite fibers exhibited uniform fiber morphologies and the fluorescence peak of the quantum dot composites was unchanged. In fact, fluorescence micrographs of the composite fibers reveal luminescent fibers with evenly distributed fluorophores that manifest SNP intermittency correlated with small clusters and single SNPs suggesting excellent dispersion in the polyelectrolyte matrix. These fluorescent composite fibrous assembles of nanoparticle-polyelectrolyte fibers are useful multifunctional materials, utilized in filtration, sensing and tissue engineering applications, with the added benefits of improved mechanical, electrical or structural characteristics over the individual components. To explore the sensing applications of these nonwoven assemblies we exposed the mats to a range of pHs and changes in humidity. The mats exhibited recoverable fluorescence quenching when exposed to high humidity and demonstrated sensitivity to changes in pH. The major impacts of this work include: (1) Electrospinning PAA/quantum dot composites for the first time and establishing the optical properties of these fibers. (2) Evaluation of the optical properties of these fibers when exposed to a range of pH's and humidity. (3) Electrospinning, for the first time, Chitosan/PAA complexed fibers with quantum dots. (4) Demonstrating, for the first time, the ability to regulate energy transfer between donor quantum dots embedded in a nanofiber and surface bound acceptors.
Initiated chemical vapor deposition of polymer thin films and coatings for biological applications
Authors:   , Bose Ranjita K. , Lau Kenneth K. S.
Published: July 2021

Initiated chemical vapor deposition (iCVD) is a surface polymerization technique performed under vacuum without the use of solvents. It uses a chemical vapor deposition environment to first activate an initiator in the gas phase, coupled with monomer adsorption onto a cooled substrate followed by a surface reaction by attaching the activated radicals to multiple monomer units to yield long polymer chains. iCVD produces exceptionally clean polymers with stoichiometric compositions, tunable molecular weights, and with no residual monomer or solvents. The overall objective of this work is to utilize iCVD to explore novel iCVD chemistries and resulting iCVD polymers relevant to biological applications and has been accomplished by performing three specific aims. First, iCVD was used to synthesize thick free standing films of poly(2-hydroxyethyl methacrylate) (PHEMA) hydrogels and the resultant polymers were found to be free from entrained monomer, resulting in good cell adhesion and noncytotoxicity towards human dermal fibroblasts, and having low nonspecific protein adsorption, thus making them suitable for potential biomedical applications. Additionally, these linear iCVD PHEMA films were found to have ultra high molecular weight with a high degree of physical chain entanglement that imparted greater mechanical strength compared to the chemically crosslinked counterparts, thus eliminating the need for hydrophobic crosslinking groups and retaining greater hydrophilicity. Second, iCVD was used to synthesize poly(ethylene glycol) (PEG) polymers important in biomedical applications. Since PEG is water soluble, iCVD was employed to graft PEG onto surfaces. In addition, a microcontact printing procedure was used to generate PEG patterns with selective grafting. These immobilized PEG substrates were shown to resist non-specific protein adsorption. A fundamental study of iCVD PEG deposition kinetics shows that the rate of polymerization and the kinetic chain length agree with a cationic polymerization mechanism. Third, iCVD was used to conformally apply polymer coatings on non-planar 3D particles to modify surface characteristics. Different iCVD processing strategies were employed to impart barrier properties to slow the release of microparticles of a crop protection compound by coating them with poly(glycidyl methacrylate) (PGMA) and poly(cyclohexyl methacrylate) (PCHMA) to obtain controlled release. In sum, this work has demonstrated that iCVD is a viable and relevant engineering pathway for the design, synthesis, and processing of polymers for biological applications. Success ultimately depends on understanding the fundamental kinetic mechanisms in iCVD polymerization and deposition.
The use of poly(N-isopropylacrylamide)-g-poly(ethylene glycol) as an injectable scaffold for repair of the injured spinal cord
Authors:   , Grous Lauren Conova , Lowman Anthony M.
Published: July 2021

Spinal cord injury (SCI) typically results in permanent functional loss. In order to repair the damaged tissue following SCI and to promote functional recovery, the non-permissive injury environment needs to be adjusted by modulating the immune reaction that follows the initial injury and leads to inflammation and expansion and also by replacing lost or damaged cells. This work investigates the feasibility of using an injectable hydrogel, based on poly(N-isopropylacryalmide) (PNIPAAm), lightly crosslinked with poly(ethylene glycol) (PEG), to serve as an injectable scaffold for local delivery of neurotrophins and cells into the injured spinal cord. This work tests the biocompatibility of the PNIPAAm-g-PEG scaffold by evaluating its ability to be injected as a viscous liquid, forming a space filling gel, and for its ability to support cell survival, without contributing to an injury-related inflammatory response. The scaffold was also evaluated for its ability to promote axonal growth through the action of released brain-derived neurotrophic factor (BDNF). Other studies include development of a device that uses sustained-release microspheres for delivery of growth factors and enzymes to the injured spinal cord. BDNF, which stimulates axon growth, was encapsulated in a polymer and combined with the PNIPAAm-g-EG scaffold. In addition, the enzyme chondroitinase (ChABC), which digests inhibitory proteoglycans that form the glial scar, has been shown to promote axonal growth past the lesion. ChABC was also encapsulated in sustainedrelease microparticles, in an attempt to stabilize the protein so it can effectively digest proteoglycans. By incorporating the most effective techniques, the final study in this work tested this delivery device in a comprehensive in vivo animal study. Animals were evaluated for the ability to recover from sensorimotor forelimb deficits associated with a cervical dorsolateral funiculotomy. Animals were analyzed in various behavioral tests prior to SCI and following SCI to assess the initial loss and potential gain of sensorimotor function over time. The ability of this multifunctional scaffold to mimic the host spinal tissue and to deliver cellular grafts and growth factors to the site of an injury, without a significant immune response, will provide a permissive niche for axonal regeneration, eventually leading to complete functional recovery.
Acceptance and commitment therapy as a novel treatment for eating disorders
Authors:   , Juarascio Adrienne Sarah , Forman Evan M.
Published: July 2021

Eating disorders are among the most challenging disorders to treat, with even state-of-the-art cognitive behavioral treatments achieving only modest success rates. One possible reason for the high rate of treatment failures for eating disorders is that existing treatments fail to attend sufficiently to critical aspects of the disorder such as experiential avoidance, poor experiential awareness, and lack of motivation. These variables are explicit targets of acceptance and commitment therapy (ACT) and as such this approach may represent an ideal intervention for eating disorders. However, ACT has not been well investigated in this population. The current study sought to examine the efficacy of an ACT treatment group for eating disorders by examining whether the addition of ACT groups to treatment as usual (TAU) at a residential treatment facility for eating disorders will improve treatment outcomes. Results indicated that individuals in the ACT condition trended towards lower levels of eating pathology at post-treatment and showed significant reductions in bulimic symptoms and lower rates of inpatient treatment by follow-up. Some preliminary evidence suggests that Anorexia Spectrum patients may have done better in the ACT condition compared to Bulimia Spectrum patients. Other moderation analyses suggested that session attendance and higher levels of ACT consistent variables at baseline predicted a better response to ACT treatment. Although most mediation analyses were not significant, a small proportion suggested that willingness to experience distress was more highly associated with treatment outcome for the ACT condition. Overall, results suggest that ACT could be a viable treatment option for individuals with eating pathology and more study of ACT as an individual treatment is warranted.
Development of a sensitive and selective laser diagnostic technique for measuring paramagnetic species
Authors:   , Lane Jamie Lee , Cernansky Nicholas Peter , Miller David Leslie
Published: July 2021

Design of advance combustion systems that are efficient and environmentally friendly increasingly incorporate numerical simulations of the reaction progress, simulations that require chemical kinetic models applicable over the entire range of reaction conditions. A deficiency of these models is in the low and intermediate temperature regime that is controlled by the hydroperoxy radical (HO2), alkyl peroxy radical (RO2), and hydroxyl radical (OH). Fundamental understanding of the underlying fuel oxidation chemistry in this regime is required to extend and improve these combustion models. A complication in making such measurements in combustion systems is the large number of strongly absorbing stable species, such as CO₂ and H₂O, that mask the absorption features of HO2 and RO2 radicals. Therefore, quantitative measurement of the small peroxy radicals requires the implementation of powerful diagnostics that are sensitive and selective enough for application in complex reacting environments. This study focuses on the development of a new laser diagnostic technique Cavity Enhanced Magneto-Optic Rotation (CEMOR) for the application of sensitive and selective measurements of paramagnetic species in combustion systems, particularly HO2 and RO2 radicals. CEMOR merges the selective ability of Magneto-Optic Rotation (MOR) spectroscopy with the sensitivity of Cavity Ringdown Spectroscopy (CRDS). CRDS in conjunction with Laser Induced Fluorescence (LIF) spectroscopy has been applied to calibrate the axial concentration profiles of OH radicals in an atmospheric pressure methane/air flame. This has allowed MOR and CEMOR to be evaluated in a combustion system. CEMOR has demonstrated an enhancement in MOR sensitivity, displaying a detection limit similar to CRDS. Assessment of the unique temporal signal behavior of CEMOR has demonstrated a power series relationship with radical concentration. The results demonstrate the potential in the diagnostics for measuring HO2 and RO2 in combustion systems. Additionally, a flash photolysis facility has been designed and developed for generating HO2 and RO2 radicals to allow diagnostic analysis using CRDS and CEMOR. Diagnostic measurements of HO2 and H₂O in the flash photolysis system have been presented.
Experimental and analytical seismic evaluation of concrete masonry-infilled steel frames retrofitted using GFRP laminates
Authors:   , El-Dakhakhni Wael Wagih , Elgaaly Mohamed , Hamid Ahmad A.
Published: July 2021

The study conducted herein focuses on investigating the retrofitting effect of face shell mortar bedding (FSMB) hollow concrete masonry-infilled steel frames (CMISF) subjected to in-plane lateral loads using glass fiber reinforced plastic (GFRP) laminates that are epoxy-bonded to the exterior faces of the infill walls. The study involves three main phases, the first phase studies the in-plane behavior of unreinforced masonry (URM) wall subassemblages strengthened with different GFRP composite laminates. A total of fifty-seven URM assemblages were tested under different loading conditions. Parameters such as the type of fibers, the number of plies, and the fibers orientation were investigated. Results showed that the application of GFRP laminates on URM has a great influence on strength, post peak behavior, as well as failure modes. An increase of 90% for compressive strength was achieved using the GFRP laminates and the shear strength increased by fourteen folds. The second phase focuses on enhancing the in-plane seismic behavior of URM infill walls when subjected to displacement controlled cyclic loading. Six full-scale single-story single bay steel frames with different wall configurations were tested. The retrofitting technique using GFRP laminates aims at creating an engineered infill wall with a well defined failure mode and a stable post peak behavior as well as containing the hazardous URM damage and preventing catastrophic failure. Results showed that the GFRP prevented both shear and tension cracking by supplying the required tensile strength. The GFRP also increased the lateral load capacity and enhanced the post peak behavior by means of stabilizing the masonry face shell and preventing its out-of-plane spalling. The stabilizing allows the wall to carry more loads and prevents sudden drop in the load carrying capacity. The third phase of the study presents an analytical model proposed for the analysis of unretrofitted GFRP-retrofitted masonry infilled frames. In this method, each masonry wall was replaced with a nonlinear, compression-only, diagonal strut that estimates the stiffness and the lateral load capacity of CMISF failing in corner crushing (CC) mode. The diagonal strut force-deformation characteristics were based on the orthotropic behavior of the masonry wall.
Trends in symptom validity, memory and psychological test performance as functions of time and malingering rating
Authors:   , McClain Maryellen , Chute Douglas L.
Published: July 2021

Detection of malingered or exaggerated cognitive deficits has received considerable attention within the neuropsychological literature in the recent past. Methods to detect such phenomena have been developed, including specific tests of malingering as well as methods by which to analyze data from existing tests. Questions regarding the utility of these various methods continue to be debated within the field, and neuropsychologists have speculated that litigating patients are being made aware of specific malingering detection methods by attorneys as well as Internet websites devoted to such topics. It was hypothesized that scores on symptom validity measures would normalize over time, with fewer subjects classified as malingering based on their scores on these tests, ostensibly due to prior knowledge of their content and purpose. In addition, significant differences were expected to emerge on tests specific tests of memory using a recognition format as a function of clinical judgment of rating probability. Patients rated as malingerers were expected to exaggerate symptoms of emotional distress with significantly greater frequency than patients rated as not malingering, as evidenced by their responses to the Minnesota Multiphasic Personality Inventory - Second Edition (MMPI-II), the Beck Depression Inventory - Second Edition (BDI-II) and the Beck Anxiety Inventory (BAI), and were expected to make significantly more subjective complaints of memory dysfunction than those patients rated as non-malingerers. Archival data collected on 1290 subjects between 1999 and 2003 were examined in this study, and were extracted from the Tulane University Neuropsychology Laboratory database. Non-parametric statistical procedures were used, due to the non-normal distribution of the data, and included Kruskal-Wallis analysis of variance procedures and follow-up Mann-Whitney U tests for all pairwise comparisons. The results failed to support the expected trends toward normal scores for the symptom validity measures. However, scores on tests of recognition memory for verbal and visual materials, as well as on the BAI and the Hs and Hy scales of the MMPI-2 were significantly lower for those subjects rated as absolute malingerers compared to those rated as not malingering The rate of subjective complaints of memory dysfunction was similar for all subjects.
Control of aircraft operating under adverse conditions
Authors:   , Salman Mishah Uzziél , Chang Bor-Chin
Published: July 2021

Almost all aircraft in use today rely on some form of automatic control system to remain safely aloft. Though control under nominal conditions is a mature field, control methods are less developed for airborne vehicles operating beyond their nominal flight envelopes. Adversities like loss-of-control and upset conditions affect all variations of aircraft and are thus of great concern. Two flying vehicles operating under different adverse conditions are explored in this study: a spinning gun-launched projectile and a transport aircraft. It is shown that similar closed-loop output-tracking regulation and H2 control methods can be employed to safely control each respective system under dangerous circumstances. For the first vehicle, a control scheme is proposed that can compensate for the confiing angle of a gun launched projectile and allow front-mounted canards to efficiently change the projectile flight path without reaching an aerodynamic stall condition. The problem is formulated as a tracking control problem where the reference signal is a sinusoidal input of non-zero bias. The sinusoidal component directly compensates for the body precession, while the non-zero bias imparts a trajectory-altering control action. This approach enables the canard actuator angles to be efficiently regulated with respect to the vehicle's heading direction to minimize drag and prevent aerodynamic stall. For the second vehicle, a civil transport jet actuator jam failure scenario is explored utilizing the NASA AirSTAR Generic Transport Model (GTM). A control algorithm is developed to mitigate the actuator jam using a reconfigurable output-tracking regulator. The regulator is developed using a servomechanism formulation where the failed control surface is modeled as an exogenous input to the degraded plant. The approach exploits a set of linear controllers selectively enabled using switching control and outer-loop compensators to optimally track a desired reference input with the remaining available control surfaces and control authority. This approach addresses the loss-of-control authority over the failed control surface in addition to the persistent disturbance input that arises from the jammed control surface.
Exploration of the fundamentals and quantitative applications of matrix assisted laser desorption ionization time-of-flight mass spectrometry (MALDI TOFMS) in polymer analysis
Authors:   , Szyszka Renata , Owens Kevin Glenn
Published: July 2021

Electrospray deposition (ESD) is used to prepare synthetic polymer samples for analysis by MALDI-TOFMS. Detailed surface characterization of these samples using atomic force and optical microscopy was undertaken to improve the precision of the sample preparation process, which is particularly important when ESD is utilized for deposition of the matrix for mass spectral imaging experiments. It is demonstrated that the degree of matrix solution saturation is a critical parameter affecting the size of the solid droplets on the surface and the surface coverage. MALDI mass spectrometry is developed as a method to measure both the surface coverage and thickness of the ESD samples. The method enables determination of the minimum spray time required to obtain one monolayer of ESD droplets, and it can be used to characterize the sample spot profile with regards to sample coverage as well as the sample thickness. The effect of time in vacuum on the matrix stability, solid droplet size and surface coverage is also demonstrated. Significant evaporation of the sample during vacuum exposure is shown to decrease surface coverage and affect the MALDI analyte signal. The importance of both the matrix-to-analyte and salt-to-analyte ratios on the cationization of synthetic polymer samples in MALDI is studied using a series of poly(ethylene glycol) (PEG) and poly-(ethylene glycol) monomethyl ether samples of various molecular weights. This work suggests a competition between the matrix, higher matrix clusters and the analyte for the cationization reagent in the MALDI experiment. Visually unusual "donut-like" sample spots are recorded for samples electrosprayed using CHCA matrix containing high salt concentrations. Confocal laser scanning microscopy reveals that spherical nano-particles are located in the outer ring while more cylindrical particles are found in the center of the spot. The polymer analyte signal shows an enhancement in the central portion of the spots, while salt-adducts of the matrix show enhanced signal in the outer ring. A combined MALDI standard additions/internal standard method is developed and used to measure the amount of residual PEG in a series of ethoxylated surfactant samples with various hydrophobic-hydrophilic balance values. Good quantitative results are obtained as verified by standard HPLC methodology.
Capital jury sentencing recommendations
Authors:   , Wolbransky Melinda F. , Goldstein Naomi E. Sevin
Published: July 2021

Over the past 10 years, the United States Supreme Court has created two categorical exceptions to the death penalty: the young and individuals with mental retardation. Researchers and scholars have suggested that defendants diagnosed with severe mental illnesses will be the next categorical exclusion, a decision that could affect up to 10% of death row inmates. It is, therefore, critical to evaluate jury decision making in capital cases as it relates to mental illness - a factor that will be taken into consideration if the Court decides to hear this issue. The present study examined archival court data from 368 North Carolina capital cases. We evaluated how mitigating circumstances related to male defendants' (N=326) mental illness related to juries' capital sentencing decisions. Results suggest that the relationship between mental illness-related mitigating factors and jury decision making may differ depending on the specific mitigating factor presented to the jury. Both statutorily defined mental illness-related mitigating factors-("capacity to appreciate wrongfulness or conform conduct" and "mental or emotional disturbance") - were significantly related to sentencing decisions. However, neither the (1) presentation of, nor (2) jury agreement with non-statutory mental illness-related mitigating factors were significant predictors of sentencing decision. The broad legal implications for defense attorneys, mental health experts, judges, and policy makers are discussed.
The study of water transport in polylactide and polylactide derivatives
Authors:   , Du An , Cairncross Richard Allan
Published: July 2021

Bio-based polymers have numerous potential advantages over traditional polymers. Polylactide (PLA) is a biodegradable and environmentally friendly polyester that is made from renewable sources. However, the moisture barrier properties in PLA are still poorly understood. That is one of the major problems preventing PLA from being competitive with petroleum-based polymers in food packaging applications. The objective of this research is to study water transport properties in PLA with the final goal to improve its moisture barrier properties. This dissertation reported water sorption and permeation in commercial and modified polylactide (PLA) with detailed mechanisms and characterization studies. Modified PLA or PLA's derivatives were prepared by varying aliphatic content with different end groups, copolymerization, and polymer blending with composite particles. Water sorption in PLA was studied via the quartz crystal microbalance/heat conduction calorimetry (QCM/HCC) technique. Theoretical models were applied to compare with experimental results. Water barrier properties in PLA are improved by varying aliphatic content with different hydrophobic end groups and fabricating nanocomposites but not by graft copolymerization with rubbery backbone materials. This dissertation significantly contributes to a complete understanding of different factors that can affect moisture transport properties in PLA, which provides a guideline in designing a material with optimal barrier properties by applying a certain combination of factors.
The oxidation of JP-8 and its surrogates in the low and intermediate temperature regime
Authors:   , Lenhert David Burton , Cernansky Nicholas Peter , Miller David Leslie
Published: July 2021

Although not typically considered a fuel for diesel engines, the U.S. Department of Defense (DoD) directive 4140.25 mandated the aviation fuel JP-8 to be the 'universal'fuel for all military applications. This logistical simplification was extensively field tested and JP-8 has been successfully used in the U.S. Army's compression ignition (CI) engines. However, wide variations in cetane index, aromatic content, naphthene content, and fuel additives were observed (JP-8's specifications are intentionally broad to keep cost at a minimum) and the impact of these variations on CI engine operations are notwell understood. During this research, the impact of these variations on the critical autoignition behavior were addressed by the oxidation of several samples of JP-8 and Jet- A in a Pressurized Flow Reactor (PFR) Facility at elevated pressures over a range of temperatures (600 - 800 K). This provided insight into which fuel properties and theirassociated variations had the most significant impact on CI engine operation. Furthermore, due to the complexity and variability of full-boiling range fuels, such as JP-8, researchers typically develop simplified blends, called surrogates, to study the combustion processes, and ultimately develop combustion models based on their results. To further investigate the oxidation of JP-8, a 4-component surrogate was utilized which roughly matched the 'average' JP-8 reactivity measured in the first phase of this research. The surrogate was a mixture of 43% n-dodecane, 27% iso-cetane, 15% methylcyclohexane, and 15% [alpha]-methyl-naphthalene. Neat, binary mixtures of the components, and the full surrogate were oxidized in the PFR and stable intermediate and product species were identified and quantified using permanent gas analyzers, and gas chromatography with mass spectrometry (GC/MS). These detailed studies provided kinetic and mechanistic information in the low and intermediate temperature ranges (600 - 1000 K) and at elevated pressures. The experimental results provided profiles which will be used in future studies to develop detailed and reduced kinetic models for the ignition and oxidation of these fuels.
Endothelial cell mechanotransduction in diabetes
Authors:   , Kemeny Steven Frank , Clyne Alisa Morss
Published: July 2021

Diabetes is a worldwide epidemic, and people with diabetes suffer from morbidity and mortality related to cardiovascular disease. Vascular endothelial cells are mechanosensitive to fluid shear stress, and hyperglycemia, a hallmark of diabetes, affects endothelial cell function. Clinical evidence suggests interaction between mechanics and high glucose, since diabetic patients have accelerated atherosclerosis. The central objective of this thesis is to examine how native and glycated collagen substrates and hyper- and hypoglycemic conditions alter endothelial cell fluid shear stress response and adhesion strength. Endothelial cells were cultured on either native or glycated collagen coated substrates, and in three glucose conditions: low (1 mM), normal (5.5 mM) and high glucose (33 mM). Endothelial shear stress response was studied using a parallel plate flow system, and a spinning disc apparatus was used to quantify endothelial cell adhesion strength. Glycated collagen substrates, low glucose medium, and high glucose medium prevented endothelial cell alignment and reduced nitric oxide production with shear stress exposure and also increased endothelial cell adhesion strength. While these three diabetic conditions shared impaired signaling pathways, including decreased focal adhesion kinase and endothelial nitric oxide synthase phosphorylation, the underlying mechanisms for altered cell response were different. Endothelial cells used V 3 integrins to attach to glycated collagen instead of 2 1 integrins to attach to native collagen, which affected mechanotransduction pathways and adhesion strength. In high glucose, endothelial cells produced increased reactive oxygen species and protein kinase C, which inhibited focal adhesion kinase phosphorylation. Endothelial cells in low glucose released vascular endothelial growth factor, which disrupted the mechanosensory complex and activated integrins. These results show that endothelial cell response to a physiologically relevant mechanical environment is dysfunctional under hyperglycemia conditions. Clinically, endothelial cell phenotypic changes in altered glucose play a critical role in the early, accelerated atherosclerosis seen in diabetic patients. This research confirms the importance of strict glucose control to reduce diabetic vascular complications.
Minimalist models for the pre-unfolding oscillations and photo-switching properties of single GFP-like molecules
Authors:   , Lin Hanbing , Yuan Jian-Min
Published: July 2021

Green fluorescent proteins (GFP) and GFP-like proteins have become one of the most important tools for imaging of biological processes in live cells. They exhibit photo-switching properties, which include photo-activation/deactivation and color switching. Single GFP-mut2 molecule immobilized in silica gels exhibits interesting oscillatory behaviors, right before it unfolds in the presence of denaturants. These oscillations are attributed to the switching between a neutral and an anionic chemical state of the chromophore. The associated off-time distribution of green fluorescence also changes from an exponential curve of the native state to a near-Gaussian distribution caused by the unfolding process. To understand the nature of this oscillatory behavior as well as other photo-switching properties of GFP-like molecules, we have carried out a theoretical study of these proteins using stochastic dynamics. Two stochastic methods are employed: one is analytical and the other is numerical, solving a set of rate equations based on the Gillespie algorithm. Aiming at constructing a minimalist model for the oscillatory behaviors we have examined a three-state, a four-state, as well as a six-state model for such processes. Within physically reasonable ranges of the transition rates, a three-state model cannot explain observed effects of GFP-mut2 and a four-state model is sufficient in generating off-time distributions peaking near the observed values. However, for the same set of rates, the intensities of the fluorescent emissions do not agree with the observed values. The six-state model does give results in reasonable agreement with the experiment data for GFP-mut2. A sensitivity analysis is also carried out to determine the effects of transition rates on the fluorescent intensities. The methods can also be applied to other photo-switching GFP-like fluorescent proteins, which we demonstrate with the example of Dronpa.
Canonical behavior patterns
Authors:   , Mankowski Walter C. , Salvucci Dario D. , Shokoufandeh Ali
Published: July 2021

A common problem in many areas of behavioral research is the analysis of the large volume of protocol data recorded during the execution of tasks. This dissertation describes a new automated method of protocol analysis to find canonical behaviors: a small subset of behavior protocols that are most representative of the full data set. The method I have developed takes advantage of recent algorithmic developments in pattern recognition. By adapting these methods to the analysis of behavior protocols, I provide a new tool for analysts working with large datasets that are infeasible to study using current methods. The method I propose can also be used as an important complement to existing sequential protocol analysis techniques, by allowing researchers to build their models based on a few highly representative samples. The contributions of this dissertation include the adaptation of the method to the analysis of behavior protocols; the development of similarity measures appropriate to behavior protocols; an extension of the method to work in oriented topologies; and a demonstration of the method's utility in real-world problem domains, particularly web browsing and driving.
Essays in corporate governance
Authors:   , Pedersen David J. , Walkling Ralph A.
Published: July 2021

Corporate governance deals with the ways in which suppliers of capital to firms improve their chances of getting a return on their investment (Shleifer and Vishny (1997)). In this dissertation, I analyze three aspects of governance that impact the incentives, policies, and decisions of the firm. In the first essay, Blockholder Attention, I recast the study of blockholder monitoring from a question of whether firms will listen to one that additionally asks are investors willing to talk. Given resource constraints, investors cannot talk to all of the firms they own and allocate their attention to those positions in which they have the most capital invested. Once I isolate blocks that receive the requisite attention, I find robust evidence of effective monitoring: firms with one of these High Attention Blocks experience significant improvements in compensation policies, turnover decisions, and acquisitions. Firms with blocks of relatively less importance do not enjoy any of these gains. In the second essay, CEO Skill in Corporate Acquisitions, I, along with my co-authors, Jeff Jaffe and Torben Voetmann, examine the incidence of differential skill in acquisition decisions. While we find significant evidence of persistent bidder returns when a firm retains the same CEO for consecutive acquisitions, it appears negative skill, or the repeated act of conducting value-destroying acquisitions, is the dominant trait. In the third essay, The Price Effects of Event-Risk Protection: The Results from a Natural Experiment, my co-authors, Karl Okamoto and Natalie Pedersen, and I use court rulings related to the $48.5B LBO of Bell Canada to isolate the pricing effects of change-in-control covenants. Consistent with the existing literature, we find significant evidence that these covenants are priced and this judicial intervention upset the existing bargain between bondholders and issuers.
Formulation, fabrication, and drug loading of PEGylated ultrasound contrast agents
Authors:   , Andorko James Imre , Wheatley Margaret A.
Published: July 2021

Previous research has shown that when injected intravenously, drug-loaded polymeric ultrasound contrast agents (UCA) accumulate within the liver and spleen due to recognition by the complement proteins within the blood and uptake by the mononuclear phagocyte system (MPS). The MPS and complement systems are part of the body's natural immune system and should be avoided to allow for proper delivery of drug to the desired site. This study investigates two means of incorporating polyethylene glycol (PEG) into the shell of UCA to facilitate the avoidance mechanisms. PEG is a well-researched molecule used for immune system avoidance. The first route used a PEG-polylactic acid (PLA) copolymer to create the UCA via a water-oil-water emulsion technique. A second approach employed TPGS (d-[alpha] tocopheryl polyethylene glycol 1000 succinate or vitamin E) as a surfactant during the creation of the UCA from pure PLA. The resulting formulations of PEGylated UCA were compared to regular PLA UCA to determine the impact of the addition of PEG on the acoustic, inherent, and drug loading properties of the UCA. In this study, UCA were successfully created using the PEG-PLA copolymer in conjunction with PLA. The optimal PEG-PLA UCA were seen to have an average size less than 3[mu]m, maximal acoustic enhancement over 15dB, a half-life of approximately 10 minutes, and a negative surface charge which was similar to the control. These PEG-PLA UCA did show differences in the surface morphology and the drug loading properties. The PEG-PLA UCA had a collapsed polymer shell which caused a wrinkled surface and may have led to the very low encapsulation of drug (8% encapsulation efficiency). The TPGS UCA successfully produced through this design also had properties similar to the control. These UCA had a maximal acoustic enhancement over 15dB, a half-life around 10 minutes, a negative surface charge, and a smooth surface morphology. However, the size of the TPGS UCA was much more varied than the control, ranging from under 2[mu]m to almost 20[mu]m. The TPGS UCA, similarly to the PEG-PLA UCA, were unable to be successfully loaded with large amounts of drug, having on 2.6% encapsulation efficiency. Both the PEG-PLA UCA and the TPGS UCA showed a statistically significant decrease (P<0.05) in the amount of activated C3a protein compared to the control. This reduction of C3a activity would likely correlate to increased circulation time within the blood stream for these UCA due to avoiding detection of the immune system.
The inconvenient truth in boundary negotiations and public participation in the production of scientific and technological knowledge
Authors:   , Asprakis Antonis James , Slaton Amy Elisabeth , Porpora Douglas V.
Published: July 2021

Boundary negotiations involving the appropriate space for public involvement in the production of scientific and technological knowledge can serve as a contentious area in the Science, Technology, and Society/Sociology of Knowledge discourse. Using H. M. Collins and Robert Evans' expertise-favoring "Third Wave" model, this media discourse analysis examined whether the top-down conveyance of information on global warming provided by journalists and other "translational experts" is able to provide an appropriate space for the views of diverse stakeholders to be incorporated in democratic deliberations of technological as well as public policy actions to reduce global carbon emissions. The results of this analysis indicate that hidden power flows as well as adherence to specific socio-political worldviews in the editorials and op-ed opinion pieces of three leading U.S. newspapers may provide significant obstacles in the efforts of developing world advocates to carve out a space for themselves in the public deliberations of powerful Western nations such as the United States within the framework of a top-down relationship between the public and scientific/technological experts.
Implementation of a user-centered approach in the creation of a supplemental application to augment anatomy education
Authors:   , Connell Kristopher J. , Mauriello David A.
Published: July 2021

Anatomy is a key knowledge domain for medical and healthcare professionals; it is also a key part of the foundation of knowledge for students studying within the medical field. Due to limited resources, institutions are looking to modern technological solutions to augment the traditional classroom experience. However, the current resources available to educators fail to fully meet the needs of students, and a user-centered design is essential to maximize the effectiveness of the resource and facilitate a meaningful learning experience. The purpose of my thesis is to produce the proof of concept for an interactive application to supplement traditional anatomy education. This application leverages digital media technologies and theory and was informed by educational and cognitive theories with the goal of improving the learning experience of the user.
Performance enhancement in public speaking anxiety and associated changes in brain activity
Authors:   , Glassman Lisa Hayley , Forman Evan M. , Herbert James D. , Izzetoglu Meltem Alkan , Ruocco Anthony C.
Published: July 2021

Individuals with public speaking phobia experience fear and avoidance that can cause extreme distress, impaired speaking performance, and associated problems in psychosocial functioning. Most extant interventions for public speaking phobia tend to focus on the reduction of anxiety and avoidance, but neglect performance. Additionally, very little is known about the neurophysiological mechanisms responsible for social performance under conditions of high anxiety. The current study compared the efficacy of two cognitive behavioral treatments (standard Beckian Cognitive Behavioral Therapy (CT) versus an acceptance-based behavior therapy called Acceptance and Commitment Therapy (ACT)) in enhancing public speaking performance and coping with anxiety. Secondarily, brain activation was measured to explore the relationships between treatment type, anxiety, performance, and prefrontal brain oxygenation. Individuals (n=19) with high public speaking anxiety were randomized to a 90-minute ACT or CT intervention. Assessments took place at pre- and post-treatment and included self-rated and objective anxiety measures, a behavioral assessment, ACT and CT process measures, and functional near-infrared spectroscopy (fNIRS) readings. Results indicated that participants in the ACT condition experienced greater improvements in observer-rated performance in comparison to those in the CT condition. Individuals in the ACT condition exhibited greater reductions in oxygenated hemoglobin in the right dorsolateral prefrontal cortex following the intervention than those in the CT condition. Furthermore, blood volume decreased in the ACT condition and increased in the CT condition between pre- and post-treatment assessments. These results suggest that ACT may have a superior performance effect in this population, and that these two treatment modalities have different effects in the brain.
Novel organic-inorganic hybrid mesoporous materials and nanocomposites
Authors:   , Feng Qiuwei , Wei Yen
Published: July 2021

Organic-inorganic hybrid mesoporous materials have been prepared successfully via the nonsurfactant templated sol-gel pathway using dibenzoyl-L-tartaric acid (DBTA) as the templating compound. Styrene and methyl methacrylate polymers have been incorporated into the mesoporous silica matrix on the molecular level. The synthetic conditions have been systematically studied and optimized. Titania based mesoporous materials have also been made using nonionic polyethylene glycol surfactant as the pore forming or structure-directing agent. In all of the above mesoporous materials, pore structures have been studied in detail by Transmission Electron Microscopy (TEM), X-ray diffraction and Brunauer-Emmett-Teller (BET) characterizations. The relationship between the template concentration and the pore parameters has been established. This nonsurfactant templated pathway possesses many advantages over the known surfactant approaches such as low cost, environment friendly and biocompatibility. To overcome the drawback of nonsurfactant mesoporous materials that lack a well ordered pore structure, a flow induced synthesis has been attempted to orientate the sol-gel solution in order to obtain aligned pore structures. The versatility of this nonsurfactant templated pathway can even be extended to the making of organic-inorganic hybrid nanocomposite materials. On the basis of this approach, polymer-silica nanocomposite materials have been prepared using a polymerizable template. It is shown that the organic monomer such as hydroxethylmethacrylate can act as a template in making nanoporous silica materials and then be further polymerized through a post synthesis technique. The properties and morphology of this new material have been studied by Differential Scanning Calorimetry (DSC), Scanning Electron Microscopy (SEM) and Infrared Absorption Spectroscopy (FTIR). Electroactive organic-inorganic hybrid materials have also been synthesized via the sol-gel process. A coupling agent was used to covalently bond the organic and inorganic species. The morphology and conductivity of the products have been investigated.
Fabrication and characterization of inverted organic photovoltaics
Authors:   , Perlenfein Tyler John , Baxter Jason B.
Published: July 2021

The field of organic photovoltaics has been growing rapidly for more than a decade. With the low materials and processing costs, high materials usage and scalability, and flexible applications, the plastic solar cell is on the cusp of economic feasibility. To make this type of cell more attractive, the module efficiency and lifetime must be improved by a significant margin. In this work, the essential materials of an organic solar cell are explored by physical experimentation. Through systematic parameter studies, the photoactive layer of the cell is optimized for thickness and annealing conditions while the hole and electron transport layers are optimized for ease of deposition and contribution to overall cell performance. More advanced techniques for characterization are discussed, including an introduction to electrochemical impedance spectroscopy and a demonstration of how the quantum efficiencies of a cell can be measured. All experiments and discussion are conducted with the ultimate goal of increasing the efficiency of the organic solar cell. The most efficient cells produced in this work fall in the 3.1 - 3.3 % range, with Jsc of 10 - 11 mA/cm2 and Voc of 540 mV. These air-stable cells used an inverted architecture consisting of an ITO/TiOx/P3HT:PCBM/MoO3/Ag stack.
Testing an alternative hypothesis for cognitive bias modification for public speaking anxiety
Authors:   , Rabin Stephanie Justine , Herbert James D.
Published: July 2021

Anxious and depressed individuals tend to show biases in cognitions and implicit attitudes when presented with affectively-laden stimuli relevant to their specific mood state. Cognitive Bias Modification (CBM) is a relatively new area of research based on the notion that these biases can be changed relatively quickly and easily, resulting in symptom reduction. CBM attempts to modify maladaptive behaviors and cognitions by training individuals to attend to more desirable stimuli rather than the stimuli that are consistent with the individuals' cognitive bias. In some cases, CBM appears to require as little as a single computer-based intervention. Several recent studies (e.g., Amir, Beard, Burns, & Bomyea, 2009; Amir, Beard, Taylor, et al., 2009; Amir, Weber, Beard, Bomyea, & Taylor, 2008; Li, Tan, Qian, & Liu, 2008; Schmidt, Richey, Buckner, & Timpano, 2009) have demonstrated that computer-based CBM treatments, compared with control groups, reduce social anxiety in both clinical and non-clinical samples. However, the design of these studies leaves open the possibility that simple attentional training, rather than bias modification per se, is responsible for the treatment effects. The current study attempted to replicate a one-session CBM study for public speaking (Amir et al., 2008) to verify this phenomenon, as well as test this alternative hypothesis by implementing a second control group that underwent simple attentional training. In general, results from all outcome measures failed to support both the replication and alternative hypothesis. This raises the question of whether CBM treatment effects are robust and reliable, and whether CBM is ready to be marketed to clinical populations as a viable treatment option.