bluuebunny/crossref_metadata_2025 huggingface dataset:
Thermoacoustic convection and transport in supercritical fluids under normal and micro-gravity conditions
Authors:   , Lei Zhiheng , Farouk Bakhtier
Published: July 2021

The generation, propagation and dissipation of thermally induced and mechanically driven acoustic waves in supercritical nitrogen and carbon dioxide were studied. Supercritical fluids are widely used in various industrial and laboratory processes as substitutes for organic solvents. These fluids also have high compressibilities, high thermal conductivities, low viscosities, and low thermal diffusivities. As the thermal diffusivity tends to zero near the critical point, acoustic waves are believed to be the primary reason for fast thermal equilibration in supercritical fluids. The compressible form of Navier-Stokes equations for Newtonian fluids was considered to model the supercritical fluids. A high-order explicit numerical scheme (FCT: flux-corrected transport, along with an accurate wall density boundary condition, was applied to accurately track the acoustic waves. The property variations (pressure, internal energy, viscosity, and thermal conductivity) of the supercritical fluids (carbon dioxide and nitrogen) as functions of temperature and density were obtained from the NIST Standard Reference Database 12 instead of simplified equations for real gases. Both one-and two-dimensional computational fluid dynamics models were developed for predicting the temporal evolution of pressure, density, temperature and flow field in supercritical fluids due to thermal and mechanical excitations. The flow fields and heat transport induced by thermally induced acoustic waves and buoyancy in supercritical fluids were investigated numerically under normal and reduced gravity conditions. The flow fields induced by mechanically driven acoustic waves in an enclosure driven by a vibrating wall were also numerically studied. The model developed was also used to investigate the interaction of thermally induced acoustic waves and mass transfer in supercritical fluids (naphthalene dissolution in supercritical carbon dioxide). The generation and propagation of thermally induced acoustic waves due to rapid heating of a solid wall in a confined supercritical fluid layer were also experimentally investigated. A high-pressure experimental facility was constructed to characterize the generation and decay of acoustic waves in supercritical nitrogen and supercritical carbon dioxide in an enclosure due to rapid heating of an end wall. The underlying physics of the 'piston effect' (fast thermal equilibration of supercritical fluids with high compressibilities) were studied and explained in detail. To the author's knowledge, this is the first attempt where detailed simulations of thermally induced and mechanically driven acoustic waves in supercritical fluids have been conducted with accurate equations of state and property functions. Better understanding of these problems will help the tailoring and optimizing the operating conditions for industrial and laboratory processes for supercritical fluids.
Preignition and autoignition behavior of the xylene isomers
Authors:   , Natelson Robert Harris , Cernansky Nicholas Peter , Miller David Leslie
Published: July 2021

The relative preignition and autoignition reactivity of the xylene isomers (o-, mand p-xylene, or 1,2-, 1,3-, and 1,4-dimethylbenzene) has been studied. The principal objectives were to determine the relative reactivity among the isomers and the key oxidation branching pathways. Preignition experiments were conducted in a pressurized flow reactor facility at 600-850 K temperatures, 8 atm pressure, and lean equivalence ratios. Online analysis of the data included carbon monoxide and carbon dioxide measurements using a nondispersive infrared analyzer and molecular oxygen measurements using an electrochemical oxygen cell. Offline analysis, for identification and quantification of intermediate species, was performed using gas chromatography with flame ionization detection and coupling to a mass spectrometer. Additional experiments were conducted in a single cylinder research engine. Neat o- and m-xylene were oxidized in the PFR under preignition conditions. They showed no reactivity, so mixtures of each isomer with n-dodecane were tested and compared, and intermediate species were identified. This data helped resolve a recent controversy regarding the relative reactivity of the xylene isomers. Additionally, a mixture of p-xylene / n-dodecane was studied. To study the autoignition of the xylenes, the isomers neat, in binary mixtures with n-decane, and in six-component JP-8 surrogates were tested in the single cylinder research engine. The experimental data were analyzed and compared to existing chemical kinetic models, and it was concluded that at lower temperatures (<850 K), the xylenes show similar reactivity, and at higher temperatures, o-xylene is the more reactive isomer. The data can be used for the improvement of xylene chemical kinetic models, and the conclusions from this study will aid in the selection of the appropriate xylene isomer for JP-8 surrogate fuels.
Separation of use or misuse
Authors:   , Dispensa Jaclyn Marisa , Brulle Robert Joseph
Published: July 2021

In Pennsylvania, sprawl, simply known as unplanned suburban development, is consuming land at a rate greater than the population increase. Sprawl continues for several reasons many of which are uninvestigated. The goals of this research are to evaluate the process of zoning variances and zoning boards from 1981 - 2001: the composition of the zoning board, the board's decision-making, and the result of their decision-making on the environment. Zoning boards wield power over special exceptions and zoning variances; unknowingly, variances may be requested before new development begins, thus these variance requests are required for development to continue or even to occur. The process is compared to Molotch's Growth Machine theory which states that localities are in economic competition with other localities, therefore entities and individuals that support those entities (real estate professionals, lawyers, judges and the like) will work towards the economic growth of their area as it benefits themselves in return. As a result of the Growth Machine process, regulations are hardly enforced, specifically when zoning becomes too burdensome on the real estate, zoning is changed and/or variances given. This research investigates this process in eight townships of Chester County, Pennsylvania: Birmingham, East Bradford, East Goshen, Easttown, East Whiteland, Pennsbury, Tredyffrin and Westtown. Research findings show that the Growth Machine is more prevalent in Birmingham, Easttown, Pennsbury, and Tredyffrin. Elements of the Growth Machine include high overall approval ratings of zoning variances, percentage of variances illegally approved, influence of townships' economics in approval ratings, and significant differences identified among approval ratings for commercial and residential environmental variances. The presence of real-estate professionals and little professional and gender diversity may be elements, but not necessarily deciding factors as well. In addition, zoning variances contribute to increases in impervious surface. This research represents a robust evaluation of the process of zoning board development, decision-making, and the environmental effects of zoning variances, and how zoning variances and boards play an important role in the contribution to sprawling development.
Decision making training in a jail setting
Authors:   , Batastini Ashley Brianne , Nezu Christine M.
Published: July 2021

Thresholds is a cognitive-skills intervention that was developed based on the idea that individuals who engage in criminal activity lack the appropriate thinking skills, such as decision-making, to achieve their goals in socially acceptable ways. It is currently being delivered in several facilities throughout southeastern Pennsylvania and Delaware. The primary purpose of this study was to examine whether offenders who completed the Thresholds Program have lower recidivism rates than offenders who either did not receive the full dosage of treatment or who did not participate in the program. Overall, results indicate no significant differences in recidivism rates among study conditions. However, there were several gender and age differences found between groups. Secondarily, this study examined which factors best predict future criminal behavior. Participants in the non-treatment comparison group were at a significantly higher risk for re-offending than participants with at least some treatment exposure. No other predictor variables were significantly related to recidivism. Limitations and suggestions for future research are discussed.
The functional role of Th-POK in lineage commitment during T-cell development
Authors:   , Park Kyewon , Papazoglou Elisabeth S.
Published: July 2021

T lymphocytes develop in the thymus through multiple stages (DN, DP and SP) during which their survival and lineage are determined. During thymocyte maturation, T-cell Receptor (TCR) signaling induces important downstream mediators of differentiation. ThPOK (T-helper inducing POZ-Kruppel factor) has been identified as a master regulator of lineage commitment at the CD4/CD8 branch point, and is selectively induced in class II-restricted thymocytes, suggesting that it is upregulated by strong TCR signals. In order to identify upstream signaling pathways responsible for ThPOK induction, we mapped key transcriptional control elements at the ThPOK locus. These studies show that a dual silencer/enhancer element is primarily responsible for selective induction of ThPOK. We are currently attempting to identify key factors that bind to and regulate activity of this element during thymocytedevelopment. Given that [gamma][delta] lineage commitment, like CD4 commitment, may be decided by relative TCR signal strength, it is possible that the same downstream effectors may be involved in both processes. However, the potential role of ThPOK in [gamma][delta] commitment has not yet been explored. By carrying out in vitro stimulation of [gamma][delta] thymocytes with anti-TCR antibody and varying ligand affinity for the transgenic KN6 [gamma][delta]TCR in vivo, we have now established that ThPOK induction in [gamma][delta]TCR+ thymocytes is controlled by TCR signaling and specifically requires a strong/ high affinity TCR ligand. Strikingly, ThPOK deficient mice show a severe reduction in mature [gamma][delta] thymocytes as well as altered V region usage in [gamma][delta] thymocytes, showing that ThPOK is important for maturation/selection of [gamma][delta] cells. ThPOK is particularly important for development of a subset of [gamma][delta] thymocytes that express V[gamma]1.1 and the NK1.1 surface marker, which has been previously referred to as NKT[gamma][delta] cells and appears to be enriched for self-reactive specificities. Conversely, in mice that express ThPOK constitutively, the proportion of mature [gamma][delta] thymocytes is greatly increased, as is the proportion of V[gamma]1.1+ thymocytes. These results demonstrate a new role for ThPOK in development of [gamma][delta] thymocytes. Future work will distinguish whether ThPOK is important for differentiation, proliferation and our lineage commitment of the [gamma][delta] subset.
Molecular simulation studies of the insulin receptor family
Authors:   , Vashisth Harish , Abrams Cameron F.
Published: July 2021

Molecular simulations of the ligands and receptors of the insulin family were conducted. First, phenol dissociation mechanisms in the pharmaceutical storage form of insulin, R6 insulin hexamer, are studied using random acceleration molecular dynamics (RAMD) simulations. Three major escape pathways for phenols are observed. Several residues that directly participate in escape events serve to resolve ambiguities from previous NMR experiments. Potentials of mean force (PMFs) along the reaction coordinate for each pathway are further resolved using steered molecular dynamics (SMD) simulations. The results for binding free energy, F, agree reasonably well within the range of known experimental and previous simulation magnitudes of this quantity. Structural analysis and energetic barriers for each pathway suggest a plausible preferred mechanism of phenolic exchange that differs from previous mechanisms, but is consistent with RAMD results. Several weakly-bound metastable states, supported by experimental evidence, are also observed. These results give detailedinsights into the dissolution kinetics of insulin hexamers. Next, the flexibility mechanisms of the ectodomains of the insulin receptor (IR) and the type-1 insulin-like growth factor receptor (IGF1R) are studied. Both receptors are observed to display asymmetric mechanisms of flexibility due to interdomain and intersubunit conformational fluctuations that do not alter their quaternary structures. Subtle variations in intersubunit buried surface areas of both receptors are observed to coincide well with these conformational fluctuations, resulting in one easily-accessible ligand binding pocket with the other blocked. Further, Monte Carlo (MC) docking simulations are used to construct all-atom structural models of the ligand/receptor complexes which are consistent with a variety of known experimental data, and provide detailed structural bases for ligand-recognition in the IR family. Finally, a large-scale conformational change in the activation-loop (A-loop) of the insulin receptor kinase domain (IRKD) is studied using temperature-accelerated molecular dynamics (TAMD). The A-loop is observed to form a transient threeturn helical conformation during TAMD, which facilitates the conserved DFG-motif (D1150, F1151, and G1152) to switch from a "D-out/F-in" to "D-in/F-out" conformation, thereby burying F1151 underneath [alpha]C-helix, and simultaneously presenting D1150 for ATP binding. These transient helical conformations of the A-loop have been observed in the crystal structures of related kinase families, and may be useful for the design of novel inhibitors targeting IRKD.
Essays on inequality, education, trade and endogenous growth
Authors:   , Hall Joshua Dennis , Laincz Christopher A.
Published: July 2021

Inequality grew substantially not only in many developed countries during the 1980s and 1990s, but also in most developing countries. Across developing and emerging economies, the growth in inequality was more severe in Latin America and Africa compared with many East Asian countries. The diverse patterns of income inequality motivate my research, which reveals the important forces underlying the dynamics of inequality. In a general equilibrium, endogenous growth model, I show trade liberalization for a developing country with a low (high) quality of education induces a growth (reduction) of within country inequality during the dynamic transition. Moreover, trade liberalization leads to significantly stronger convergence in terms of per capita output when the quality of education is high in the developing country. Using large set of developed and developing countries, I then provide empirical evidence that echnological progress increases the growth of inequality more in countries with a low quality of education. Taken together, this research shows the interaction between technological change and educational quality emerges as a principal determinant of the growth of inequality.
Functional polymer-polymer composites by nano/meso-fiber encapsulation
Authors:   , Liang Ya , Palmese Giuseppe R. , Lowman Anthony M.
Published: July 2021

This research focuses on developing functional polymer-polymer composites through fiber encapsulation. Two composite systems, poly(lactide-co-glycolide) (PLGA) - poly(vinyl alcohol) (PVA) and polypropylene (PP) - vinyl ester (VE), were investigated. The goal was to evaluate these systems for their potential applications in drug delivery and polymer toughening. Sustained, controlled release of therapeutics and mechanical stability are desired in most drug delivery systems. This can be achieved by combining PLGA and PVA. The drug release rate mainly depends on the degradation rate of PLGA, while mechanical stability is maintained by PVA hydrogels. In this work, degradation behaviors of PLGA fibers and mechanical properties of PLGA-PVA composites were investigated during incubation in PBS (pH = 7.4) at 37°C. The size of nanofibers and the PVA matrix did not have a significant impact on the degradation rate. Degradation of PLGA fibers followed pseudo first-order kinetics. PVA matrix reduced mat shrinkage from 85% to 30% and maintained mechanical integrity of composites under incubation conditions. A gradual increase of tensile strengths and moduli of composites were observed after incubation for up to eight weeks, which was comparable to PVA hydrogels. Thermosetting resins have good chemical and mechanical properties. However they are brittle, thus limiting their use in high performance composite materials. Rubber particles are usually used to toughen thermosetting resins, but they also greatly reduce mechanical properties. Rigid thermoplastic polymers have been investigated as toughening materials while limiting the loss of mechanical properties. In this work, small diameter PP fibers were used to toughen five resins. Results showed that PP greatly enhanced fracture toughness, but reduced mechanical strength of five as voids were observed at the interface. Interfacial discontinuities of composites were improved after a plasma-based surface modification using vinyltrimethoxysilane (VTMS) was conducted on PP fibers. VTMS-grafting on PP did not significantly improve mechanical properties of the composite, but slightly increased fracture toughness by improving load transfer from five to PP. Overall, the PLGA-PVA system had a controllable degradation rate and desired mechanical stability for use in drug delivery systems, while the PP-VE system provided valuable information on toughening mechanisms of thermoplastic fibers and on toughening phase selection.
Effects of extrinsic and intrinsic factors on age-associated decline in natural killer cell activity during primary influenza infection
Authors:   , Nogusa Shoko , Murasko Donna
Published: July 2021

The fastest growing segment of the U.S. population is the group of individuals over the age of 65 years. Aging is accompanied by numerous changes in immune function and is associated with an increased morbidity as well as mortality to virus infections. Influenza is a major public health concern. Each year seasonal influenza disease occurs with a number of hospitalizations. In addition, influenza and its secondary complications rank as the 4th leading cause of deaths among the elderly. An age-associated decrease and delay in cell-mediated response, a reduction in the proliferative T cell response, and an altered cytokine production in response to influenza vaccination or infection have been reported. These are parameters of adaptive immune response. However, study of innate immune response against primary influenza infection has lacked attention. Natural killer (NK) cells are an integral part of innate immunity and play a key role in controlling viral infections and foreign pathogens. Here we report that NK cells are essential for controlling influenza virus replication early during infection independent of age. Importantly, there is an age-associated impairment in influenza-inducible NK cytotoxicity and a lack of increase in NK cells at the site of infection. In addition, aged mice produced less interleukin (IL)-15 and interferon (IFN)-[gamma] compared to young mice following influenza infection. While enhancement of NK cytotoxicity in response to stimulation with IL-2 or IL-15 in vitro was comparable in young and aged mice, aged mice demonstrated significantly lower enhancement of granzyme B expression in response to IL-2 or IL-15 and of IFN-[gamma] production in response to IL-15. These results demonstrate that age-associated impairment in influenza-inducible NK cytotoxicity may be caused by a combination of extrinsic influences, i.e. limited NK stimulating cytokines in the aged environment, and intrinsic defects, i.e. a limited inability of NK cells of aged mice to respond to cytokines and possibly other stimuli. These findings suggest that NK cells may be therapeutic targets for an intervention to restore or boost inducible NK cell cytotoxicity during primary viral infection.
Two essays on financial market behavior
Authors:   , Zheng Dazhi , Chiang Thomas Chi-Nan
Published: July 2021

This dissertation studies two issues in empirical analysis of financial markets: The herd behavior in global markets and illiquidity as a risk factor to predict excess stock returns in international markets. These issues are structured into two essays. Essay #1 examines investors' herding behavior in an international setting. By applying daily data for 18 markets for the period May 25, 1988, through April 24, 2009, we obtain supportive evidence of herding in each advanced stock market (except the U.S.) and in Asian markets. No evidence of herding is found in Latin American markets in tranquil periods. We also find some evidence that return dispersion is correlated with excess trading volume, although its information is far less significant as compared with the estimated herding coefficients. By extending the testing to global markets, this study finds that stock return dispersions in the U.S. play a significant role in explaining the non-U.S. market's herding activity. With the exceptions of the U.S. and Latin American markets, herding is present in both up and down markets. Examining herding behavior in the crisis period, it is evident that herding formation is more apparent in the crisis period. There is supportive evidence that herding is present in the U.S. and Latin American markets when those markets are in crisis. Essay #2 tests the relation between expected (and contemporaneous) excess stock returns and liquidity in an international context. By applying panel regressions on monthly data from 17 markets spanning from January 1990 through March 2009, this essay finds evidence that expected excess stock returns are positively correlated with illiquidity. However, excess stock returns are negatively associated with contemporaneous illiquidity. The supporting evidence holds true for all of the advanced markets and most of emerging markets. This study also shows that risk factors from the U.S. stock and bond markets contribute to explain local excess stock returns. The findings in this essay are consistent with the U.S. evidence in the liquidity literature. This study supports the notion that illiquidity can be viewed as a general risk factor in global stock markets. Robust tests are implemented by using trading volume turnover as the proxy for illiquidity and the results still hold. While applying the model to the portfolio data, this study shows that illiquidity risk appears to be stronger for small firm stocks.
Cleaning process in high density plasma chemical vapor deposition
Authors:   , Iskenderova Kamilla , Fridman Alexander A.
Published: July 2021

One of the major emitters of perfluorocompounds (PFCs) in semiconductor manufacturing is the in situ plasma cleaning procedure performed after the chemical vapor deposition of dielectric thin films. The release of these man-made gases can contribute to the greenhouse effect. To reduce emissions of PFCs, it has developed a new plasma cleaning technology that uses a remote plasma source (RPS) to completely break down fluorine-containing gases into an effective cleaning chemical. The downstream plasma reactor consists of a plasma source, where the inductive discharge occurs; a transport region, which connects the source to the chamber; and the actual chemical vapor deposition chamber, where the fluorine radicals react with the deposition residues to form non-global-warming volatile byproducts that are pumped through the exhaust. From environmental point of view the overall method has clear benefits, however, with the new technology several new optimization problems arise. In recent years, semiconductor equipment manufacturers have put in a great effort to improve the production worthiness and the overall effectiveness of the tools. Equipment qualification procedures can be quite expensive and lengthy. The film deposition process stability is of great importance since it can be correlated to the final integrated circuit quality and yield. The chamber cleaning process can affect the stability of the film properties. The objective of this work is to concern the main aspects of the problems that prevent the remote clean process for achieving both superior chamber cleaning performance and improved environmental friendliness. In order to meet these significant technical challenges we have developed detailed numerical models of the systems involved in the downstream cleaning process. For the remote plasma source, the detailed plasma-kinetic model has been developed to describe the atomic fluorine production from NF3, CF4, and C2F6 and provided comparison of the effectiveness in decomposition of these parent molecules. In the transport tube the homogeneous and heterogeneous kinetic model was developed to analyze the recombination mechanism of atomic fluorine. To study the optimization process of gas and power consumption in the processing chamber, the numerical 2D modeling of complex plasma-chemical processes was performed.
Colocated MIMO radar using compressive sensing
Authors:   , Yu Yao , Petropulu Athina P. , Kim Youngmoo
Published: July 2021

We propose the use of compressive sensing (CS) in the context of a multi-input multioutput (MIMO) radar system that is implemented by a small scale network. Each receive node compressively samples the incoming signal, and forwards a small number of samples to a fusion center. At the fusion center, all received data are jointly processed to extract information on the potential targets via the CS approach. Since CS-based MIMO radar would require many fewer measurements than conventional MIMO radar for reliable target detection, there would be power savings during the data transmission to the fusion center, which would prolong the life of the wireless network. First, we propose a direction of arrival (DOA)-Doppler estimation approach. Assuming that the targets are sparsely located in the DOA-Doppler space, based on the samples forwarded by the receive nodes, the fusion center formulates an ℓ1-optimization problem, the solution of which yields the target DOA-Doppler information. The proposed approach achieves the superior resolution of MIMO radar with far fewer samples than required by conventional approaches. Second, we propose the use of step frequency to CS-based MIMO radar, which enables high range resolution, while transmitting narrowband pulses. For slowly moving targets, a novel approach is proposed that achieves significant complexity reduction by successively estimating angle-range and Doppler in a decoupled fashion and by employing initial estimates to further reduce the search space. Numerical results show that the achieved complexity reduction does not hurt resolution. Finally, we investigate optimal designs for the measurement matrix that is used to linearly compress the received signal. One optimality criterion amounts to decorrelating the bases that span the sparse space of the incoming signal and simultaneously enhancing signal-to-interference ratio (SIR). Another criterion targets SIRimprovement only. It is shown via simulations that, in certain cases, the measurement matrices obtained based on the aforementioned criteria can improve detection accuracy as compared to the typically used Gaussian random measurement matrix.
Immobilization of enzymes in sol-gel mesoporous silica, enzymatic digestion of biomass, and silica-curcumin hybrid materials
Authors:   , Das Sudipto , Wei Yen
Published: July 2021

This research describes the immobilization of enzymes by direct encapsulation in porous silica matrix via a nonsurfactant templated sol-gel route pioneered by our group. Nonsurfactant molecules like D-fructose have been used as a template or pore forming agent, to generate silica host materials with pores in the mesoporous range (i.e., 2 to 50nm). Our research has demonstrated that the activities of the immobilized enzymes were largely dependent on the textural properties of the silica matrix, including the specific surface area, pore volume and pore size. The immobilized enzymes exhibited up to ~ 80% activity, compared to free native enzyme. The immobilized enzyme samples also enabled easy recovery and subsequent reusability of the enzymes. Since the spatialconfinement in nanopores, the encapsulated enzymes exhibited better environmental stability. The stabilization of enzymes in high pH commercial detergent, uponencapsulation in nonsurfactant templated sol-gel silica materials, has also been exploited in this work. In this work, we have successfully demonstrated the recyclable application of our immobilized enzyme catalyst system in biomass hydrolysis. Hydrolysis efficiencies up to 81% were obtained, and subsequent reuse exhibited negligible loss in the hydrolytic activity of our immobilized enzyme catalyst. This research also describes the synthesis and characterization of a new class of curcumin-silica organic-inorganic hybrid materials. This work presents the preparation of the hybrid materials via covalent incorporation of the organic curcumin phase into the pre-hydrolyzed sol-gel silicate phase. The degree of incorporation of curcumin phase was verified by thermogravometric analysis (TGA). Materials characterization was done using FTIR, DSC and fluorescence spectroscopic techniques. This new class of inorganic-organic silica hybrid materials may find wide applications in implant and other biomedical materials with reduced inflammatory properties.
Modeling the transport and inhibition kinetics of the human multidrug resistance transporter P-glycoprotein in MDCK-II cells
Authors:   , Acharya Poulomi , Bentz Joseph Edward
Published: July 2021

The human multidrug resistance transporter P-glycoprotein (P-gp) effluxes a wide range of substrates and can be affected by a wide range of inhibitors or modulators. Many studies have presented classifications for these binding interactions, within either the context of equilibrium binding or the Michaelis-Menten enzyme analysis of the ATPase activity of P-gp. Our approach is to study P-gp transport and its inhibition using a physiologically relevant confluent monolayer of hMDR1-MDCKII cells. We measure the elementary rate constants for P-gp efflux of radiolabeled substrates and study inhibition using pair wise combinations with a different unlabeled substrate acting as the inhibitor. Our current kinetic model for P-gp has only a single kinetically relevant efflux-connected binding site. We conclude that there are at least two kinetically distinct efflux pathways through P-gp and the binding sites connected to these pathways may not be exclusive forany drug. Binding of these substrates must be cooperative which can be either positive or negative based on the substrate-inhibitor pair. From the transport and inhibition of digoxin and loperamide, we found that other transporters are responsible for uptake of these drugs into the cells and for recycling them into and from the apical membrane once P-gp has pumped them out. Each drug has a particular IC-50 for inhibiting transport of another. Exhaustive computer simulations of drug transport in the presence of "virtual inhibitors" showed that the fitted IC50 values overestimate the intrinsic dissociation constant, KI,Aq and an equation showed that this overestimate is contributed by a convolution of cell and substrate parameters. The smaller the passive permeability of the substrate, the greater is the magnitude of the overestimate of the inhibitor's dissociation constant by its IC50. These conclusions are valid for any membrane transporter whose substrates and inhibitors must pass a permeability barrier to reach their binding site on the transporter.
Mathematical modeling of a two-phase bubble-column reactor for biodiesel production from alternative feedstocks
Authors:   , Mohammed Minhazuddin , Cairncross Richard Allan
Published: July 2021

This thesis project explores the fundamental mechanisms that control biodiesel production performance in a gas-liquid bubble column reactor. A mathematical model of a biodiesel bubble-column reactor was developed that accounts for the fundamental mechanisms of mass transport, chemical reaction kinetics and chemical reaction equilibrium. This model was compared to experimental data from a semi-batch reactor to validate the model and determine some of the model parameters. The model contains several important parameters that including a characteristic absorption time scale and a characteristic reaction time scale, the ratio of which is a Damköhler number. The Damköhler number indicates whether the reactor is operating in a mass-transfer limited or reaction kinetics limited regime. It was found from model predictions that the reactor is operated under kinetics limited regime (low Da ~ 0.03). Because the model predicts the equilibrium limitations of the reaction, the model also reproduced trends of decreasing conversion and increasing conversion times when water is present in the methanol vapor feed. A steady state formulation of the transient model was derived to approximate the behavior of a cross-flow, continuous bubble-column reactor. Multistage modeling results showed that semi-batch reactor performance could be approximated when more than six reactor stages are connected in series.
Using story and animation to breakdown and explain 3D character animation
Authors:   , Bergamini Thomas Angelo , Redmann Christopher P.
Published: July 2021

The art of storytelling is important in conveying a narrative to an audience. Through the use of animation, an artist is able to convey the story visually and give their interpretation of the story to the audience. Computer generated 3D animation is becoming a popular way to tell stories in modern media, but a majority of the modern media audience does not understand how a 3D animation is created. The lack of understanding is because the 3D animation process is complex and often difficult to explain. This thesis will explore the creation of a narrative animation that is a representation of the technical process behind 3D animation. The underlying conceit of the thesis project will be explaining the technical aspects of developing a 3D character rig. The success of the project will depend on how much the audience is able to understand about the 3D character process. Through the use of filmic techniques, the audience will be shown key aspects of character animation and how each of those aspects is related to the creation of a character. The thesis will give the audience a unique perspective on character creation and allow them to see what goes on in the world of an artist. Seeing what processes are required in character creation will give the audience a better understanding and appreciation for what they see in television and in film. To judge the success of the project, a survey will be conducted using a direct audience. Audience members with a background in 3D animation will be used to judge how accurately the project depicts the creation process of character animation, and if it is explained in the best way possible. An audience not familiar with 3D animation will be used to judge how much the audience is able to learn from the animation. The audience survey will test effectiveness of story and its ability to convey ideas about character animation.
Effect of aerosol particles on DBD plasma discharge
Authors:   , De-Medonsa Boaz , Friedman Gary G.
Published: July 2021

Dielectric barrier discharge (DBD) has been proven useful in biological applications for inactivation of microorganisms in numerous occasions by treatment of surfaces and liquids [1-6]. More recently, computational modeling of large aerosols in DBD [7] as well as experimental observation of small aerosols through a DBD mesh [8] have shown that there is a strong interaction that allows for much higher rates of sterilization in air. This thesis explores the mechanism by which the aerosols and plasma interact; specifically, the reason that the treatment time required for bacteria inactivation in air is on the order of milliseconds compared to minutes on surfaces and in liquids. Two mechanisms by which the two interact were investigated; the first being the electrostatic attraction of the charged aerosols to the plasma streamers, and the other being the increased likelihood of streamer formation as a result of induced "memory effect." [9] The first mechanism is explored analytically and the second experimentally; the results are shown herein.
Studies on a new ultrasound contrast agent
Authors:   , Chitoor Shweta Naidu , Wheatley Margaret A.
Published: July 2021

Paclitaxel (Taxol) is an anti-cancer drug obtained from the bark and needles of Taxus brevifolia. It is known for its unique mode of action and used for the treatment of breast and ovarian cancer. Also, paclitaxel shows very low solubility in water and is associated with a number of toxic side effects. The currently used formulation of paclitaxel with cremophor EL results in several hypersensitivity reactions. In order to tackle this problem, there is a need to develop targeted paclitaxel therapy for cancer treatment. Since, paclitaxel is highly hydrophobic, it can be incorporated in the hydrophobic core of vesicles such as SE61, a surfactant stabilized mixture of micro and nano gas bubbles. When ultrasound is transmitted in the body and encounters a medium with different acoustic impedance, such as a gas bubble, the backscatter is greatly increased, giving contrast enhancement. Ultrasound also causes the bubble to oscillate and break releasing any entrapped drug, for example at a tumor site. This helps in controlled and target drug release, preventing the drug action on normal healthy cells. An added advantage is that ultrasound facilitates drug uptake by increasing the permeability of the cell membrane. Nanobubbles can easily pass through the capillary walls of blood vessels in the targeted tumors enabling site specific delivery of drug. The gas core of SE61 contrast agent was Paclitaxel (Taxol) is an anti-cancer drug obtained from the bark and needles of Taxus brevifolia. It is known for its unique mode of action and used for the treatment of breast and ovarian cancer. Also, paclitaxel shows very low solubility in water and is associated with a number of toxic side effects. The currently used formulation of paclitaxel with cremophor EL results in several hypersensitivity reactions. In order to tackle this problem, there is a need to develop targeted paclitaxel therapy for cancer treatment. Since, paclitaxel is highly hydrophobic, it can be incorporated in the hydrophobic core of vesicles such as SE61, a surfactant stabilized mixture of micro and nano gas bubbles. When ultrasound is transmitted in the body and encounters a medium with different acoustic impedance, such as a gas bubble, the backscatter is greatly increased, giving contrast enhancement. Ultrasound also causes the bubble to oscillate and break releasing any entrapped drug, for example at a tumor site. This helps in controlled and target drug release, preventing the drug action on normal healthy cells. An added advantage is that ultrasound facilitates drug uptake by increasing the permeability of the cell membrane. Nanobubbles can easily pass through the capillary walls of blood vessels in the targeted tumors enabling site specific delivery of drug. The gas core of SE61 contrast agent was formulation change did not affect paclitaxel encapsulation efficiency. The encapsulation efficiency of paclitaxel loaded into standard SE61 nanobubbles was 14.4% and in paclitaxel loaded newly formulated nanobubbles was 13.9%.
Evaluation of Domestic Violence Services Provided at a Pediatric Hospital
Authors:   , Weirich Christine , Villanueva Augusta M.
Published: July 2021

Despite evidence linking domestic violence (DV) exposure with a variety of adverse outcomes, formal programs addressing DV in the pediatric setting are lacking. In order to address DV, St. Christopher's Hospital for Children (SCHC) in Philadelphia, PA developed Children and Mom's Project (CAMP) in 2005. For CAMP, SCHC collaborates with Lutheran Settlement House's Bilingual Domestic Violence Program (BDVP) to screen families for DV and provide such services to those screened positive. This study focused on CAMP's evaluation with the goal to profile the characteristics of DV victims who received DV resources at SCHC, including utilization levels. Data collected between October 2005 and October 2010 on 637 DV victims were retrospectively reviewed and analyzed through descriptive and analytical statistics to assess demographic characteristics, safety markers, and service utilization. Most subjects were female, African American or Hispanic, English-speaking, 18-35 years of age, and reported having one or two dependents. Compared to national statistics of DV victims, our subjects were younger and more likely to be female, African American or Hispanic, single, and with dependents. For each subject, a median of two contacts was made, for a total of 35 minutes of services per day. Subjects who utilized DV services at least thrice, for more than 15 minutes were considered "high utilizers" (31%). Based on two safety variables, "high utilizers" confront more dangerous DV situations than "low utilizers" (<3 contacts, or 15 minutes or less of DV services). Accurate assessments of safety and stability over time were not possible due to inadequacy of the data. Future evaluation of CAMP seeks creation of a survey tool to prospectively assess health and safety outcomes of families receiving DV services.
Computational analysis of the colonic transciptome & in vitro biomarker analysis using a novel microfluidic quantum dot linked immunoassay
Authors:   , Clark Peter M. , Papazoglou Elisabeth S. , Tözeren Aydin
Published: July 2021

DNA microarray technology facilitates the high throughput analysis of transcriptional disease regulation by measuring the relative expression levels of transcripts present within a tissue. While such computational approaches have been used to study the genetic regulation of a variety of illnesses, such studies often suffer from inadequate patient sample sizes and statistical power resulting in conflicting results and lab-specific bias. In order to overcome these limitations and fully utilize the wealth of publicly available genomic data, an integrated microarray analysis method was used to analyze and interpret microarray data in the context of colonic diseases including colorectal carcinoma (CRC) and inflammatory bowel disease (IBD). The results of this work indicate widespread genetic perturbations related to IBD in which a variety of cell types are implicated including resident host enterocytes, innate and adaptive immune cells as well as native luminal microflora. Our work has identified subtle genetic differences between IBD phenotypes for the realization of disease specific therapeutic treatments as well as novel diagnostic biomarkers. Furthermore, our analysis has revealed significant overlap in the genetic regulation and predisposition to IBD, lupus, type 1 diabetes, graves disease and rheumatoid arthritis, providing the first genetic link between the enteropathic disease symptoms associated with IBD. Druggable pathways involved in these diseases as well as known therapeutic drug targets were also analyzed for the potential repositioning of existing therapeutics for the treatment of IBD. IBD patients are known to be at an elevated risk for developing colorectal carcinoma, with risk increasing with the duration of the disease. In order to better understand the phenotype shift from IBD to cancerous phenotypes, integrated microarray analysis was used to identify gene signatures, implicated pathways and novel discriminatory biomarkers for differentiating between IBD and CRC phenotypes. Our diagnostic panels were shown to accurately differentiate between phenotypes using an independent dataset for validation. In order to transition the identified biomarkers to the clinic for diagnostic use, a novel microfluidic quantum dot linked immunosorbent assay platform was developed with enhanced surface chemistry and reaction kinetics. The developed prototype has the capability of multiplexed biomarker detection within clinically relevant samples for the stratification of disease phenotypes. In order to validate our design, human samples spiked with the fecal IBD biomarker lactoferrin were analyzed. Results indicate increased sensitivity and signal to noise ratios over our predicate device, with a reduction of the limit of detection. This proof of concept device shows great promise as a portable bedside diagnostic device for multiplexed biomarker analysis within a clinical setting.
Evaluation of chronic wounds by raman spectroscopy and image processing
Authors:   , Mao Xiang , Sacan Ahmet , Papazoglou Elisabeth S.
Published: July 2021

Diabetic foot ulcer has become a major healthcare problem as the prevalence of diabetes and the related complications increase globally. Due to the underlying pathological abnormalities in diabetic patients, these ulcers do not heal in a timely and orderly fashion as acute wounds do. Objective and accurate assessment of wound healing status is needed to deliver better wound care to patients. In this research, we utilize near-infrared Raman spectroscopy to study tissue samples from diabetic foot ulcers on a small cohort of patients. We categorized wounds as healing or non-healing, harvested samples from wound debridement and collected Raman spectra from cryosectioned samples. The average spectrum of samples from healing wounds shows higher intensities at bands associated with collagen and other proteins while the non-healing group shows higher intensities at bands associated with red blood cells. Significant spectral features such as individual band intensities and pairwise intensity ratios were identified by performing unpaired t-tests between these two groups. Supervised classification using a support vector machine (SVM) classifier was conducted to classify the spectra or samples based on the spectral features. The trained SVM classifier is able to predict a spectrum's category with 85.2% accuracy. The prediction of whether a sample is from a healing or non-healing wound can be as accurate as 95.7% when the average spectrum of the sample was fed to the SVM classifier. Since the quantification of the wound area is a common clinical practice, we also applied image processing techniques to accurately detect the wound boundary in digital images of the wound. Our method derives from a combination of color based image analysis algorithms, and the method is validated by comparing the performance with manually traced boundaries of wounds in animal models and human wounds of diverse patients. Images were taken by an inexpensive digital camera under variable lighting conditions. Approximately 100 patient images and 50 animal images were analyzed and high overlap was achieved between manual tracings and calculated wound areas by our method. The simplicity of our method combined with its robustness suggests that it can be a valuable tool in clinical wound evaluations.