bluuebunny/crossref_metadata_2025 huggingface dataset:
Absolute coverage measurements of ultrathin alkali-metal films on reconstructed silicon
Authors:   , Banerjee Rajarshi , DiNardo Nicholas John
Published: July 2021

Metal/semiconductor interfaces, particularly those involving Si, are of great technological and scientific interest. In atomically abrupt interfaces, many properties are determined by interatomic interactions over a few layers, i.e., over ~1 nanometer. The initial stages of growth of an atomic layer related to structural and electronic properties are thus important to thin film behavior. Surface science studies on metal-semiconductor systems often lead to contradictory conclusions regarding bonding sites and even whether the first layer is metallic or not. A key piece of information that must be consistent with any study is the number of atoms per unit area in the first layer, which is difficult to assess directly. Alkali-metal-semiconductor systems have been studied as model abrupt interfaces for several years. Novel effects, such as electron localization, were observed. Still, determinations of absolute coverage have been lacking. This dissertation describes results of absolute coverage measurements for Cs on Si(100)(2 x 1), Si(111)(7 x 7), and Si(111)(v3 x v3)R30°-B interface, this work confirms conclusions regarding electron localization effects and introduces considerations of ion beam-induced desorption for the weakly-bound Cs layer.
Social problem-solving ability as a predictor of distress in caregiving partners to men with HIV and AIDS
Authors:   , Good William David , Nezu Christine M.
Published: July 2021

HIV and AIDS pose myriad challenges to the individuals who live with it, their families, and the medical and mental health communities who serve them. Frequently, men who are in primary relationships with men living with HIV and AIDS function as their partners' primary caregivers. The purpose of this investigation was to investigate variables that significantly contribute to the distress experienced by this group of caregivers. In this study, variables related to the caregiver (negative life events during the past year, physical health functioning, availability of and satisfaction with social support), care recipient (functional impairment), and caregiver/care recipient dyad (dyadic adjustment) were evaluated. Four hierarchical multiple regression analyses were conducted on data collected from the 44 participating caregivers. Results indicated that caregivers' satisfaction with social support resources and social problem-solving ability significantly contributed to the prediction of their level of depressive symptomatology. However, none of the aforementioned variables reliably improved the prediction of caregiver anxiety, hopelessness, or burden. The limitations of this study, its clinical implications, and suggestions for future research are discussed.
Development of programmable front-end electronics for use with ultrasound hydrophone
Authors:   , Umchid Sumet , Lewin Peter A. , Bloomfield Philip E.
Published: July 2021

Piezoelectric sensors are widely used in many bioengineering applications. However, the sensors exhibit high, on the order of MegaOhms, output impedance and, therefore, the signal generated at the output terminals of a sensor needs to be electronically conditioned prior to further use. Specifically, it is necessary to incorporate a high quality preamplifier between the sensor and analyzing equipment. Such preamplifiers are not commercially available. This work describes development of a programmable preamplifier tailored for use with miniature piezoelectric polymer hydrophones for characterization of acoustic output of ultrasound scanners. Such scanners are used in almost all medical fields and are becoming the preferred imaging modality in a variety of clinical situations. The preamplifier features 50 output impedance to eliminate transmission line phenomena, and high input resistance (1M) which minimizes loading of the hydrophone. The frequency response of the preamplifier was optimized to comply with the Food and Drug Administration (FDA) requirements; the circuit operates between 100 kHz and 40 MHz. To optimize the performance in terms of input impedance, frequency response and dynamic range, the preamplifier was implemented in two stages using application specific operational amplifiers. Visual Basic program was employed to automatically execute On/Off function of the buffer circuit. The implemented circuit topology allows fully automatic determination of key acoustic output parameters of diagnostic ultrasound scanners, which, in turn, determine the safety indicators such as Mechanical Index (MI) and Thermal Index (TI). To verify the performance of the programmable preamplifier, several ultrasound hydrophones were measured and calibrated with and without preamplifier. The measurement results are presented in terms of end-of-cable voltage sensitivity as a function of frequency. Also, the impedance of the preamplifier and programmable buffer circuit were determined as a function of frequency. In addition, the circuit's scattering parameter S21 that is its transfer function versus frequency was measured. Future work will focus on extension of the preamplifier's bandwidth up to 100 MHz.
An empirical study of major depression and memory functioning
Authors:   , Sesta Joseph John , Chute Douglas L. , Spiers Mary , Zillmer Eric
Published: July 2021

The current study revealed significantly lower scores on the Visual Memory, Delayed Recall, and Attention/Concentration indexes of the Wechsler Memory Scale-Revised (WMS-R) for inpatients with Major Deparession as compared to nondepressed contrast group. No between group differences were found for proportion of subjects to reach a learning criterion, number of trials to criterion, or percent learned by final trial. Depressed subjects showed greater information loss after delay on more complex, unstructured, uncued memory tasks. Increaed severity, scope, psychological, and physiological depressive symptoms were moderately associated with decreased performance on visual memory and delayed recall measures. The Hamilton Rating Scale for Depression, Beck Depression Inventory, and SCID were better able to predict visual memory performance than verbal. Hamilton and SCID measures of depressive symptoms were better associated with WMS-R scores than were measures from the Beck. Although comparable in visuospatial processing ability, depressed subjects scored significantly lower than contrast subjects on most WMS-R measures of visual memory. The findings suggest compromised storage of visual-spatial information in depression, although results were not conclusive. The current findings were partially consistent with the neuropsychological literature on right hemisphere-related visuospatial impairments in depression.
On homogenization and de-homogenization of composite materials
Authors:   , Yan Chang (Karen) , Wang Albert S. D.
Published: July 2021

Composite homogenization is a modeling concept that allows the description of heterogeneous materials by constitutively equivalent, homogeneous ones. The concept is universally applied to fibrous composites, resulting in many modeling approaches. But, by homogenization, the composite is voided of its physical microstructure; elements that may affect failure mechanisms physically are also voided. This fact often leads to difficulties in failure theories formulated at the homogenized material scale. De-homogenization is a reverse scheme in that the microstructure is restored, albeit locally, back in the homogenized composite. Clearly, this is done after composite homogenization and field analysis of composite structures under global loading; so the micro fields in the desired locations with restored microstructure can be recovered. The recovered micro fields may then provide the needed information for some failure theories to be formulated at the composite micro scale instead. This thesis presents a unified modeling approach for homogenization (forward) and de-homogenization (backward), applicable to unidirectional composite systems. Emphasis is placed on the uniqueness between the forward and the backward modeling processes; so the desired micro fields are truly recovered within the confines of mechanics. Micro fields in several laminates made of the UD systems are recovered; key effects that influence failure mechanisms therein are studied. An inter-scale failure theory that describes matrix cracking in laminates is then formulated, being based on the recovered micro-fields. Laminate matrix cracking in several well-documented experimental studies are simulated using the inter-scale theory. The simulation captures the major cracking characteristics that are otherwise excluded in failure theories derived at the homogenized composite scale. The general concept of homogenization/de-homogenization is applicable to all composite systems, where responses from micro-macro-global interactions are to be physically described. The approach taken in the formulation of the inter-scale theory serves as an example of both conceptual and practical importance.
Formation of carbide derived carbon coatings on SiC
Authors:   , Cambaz Zarife Göknur , Gogotsi Yury
Published: July 2021

Control over the structure of materials on nanoscale can open numerous opportunities for the development of materials with controlled properties. Carbon, which is one of the most promising materials for nanotechnology, can be produced by many different methods. One of the most versatile, in terms of a variety of structures demonstrated (graphite, porous amorphous carbon, nanotubes, graphene and diamond), is selective etching of SiC and other carbides. Since the Si atoms are extracted layer by layer, atomic level control of the carbon structures can potentially be achieved without changing the size and shape of the sample. Carbon produced by this method is called Carbide-Derived Carbon (CDC). In this work, CDC formation was studied on single crystalline 3C-SiC whiskers and 6H-SiC wafers by chlorination and vacuum decomposition at high temperatures with the goals to better understand the mechanism of carbide-to-carbon transformation and determine conditions for synthesis of desired carbon structures. The reaction kinetics, morphology and shape conservation were investigated at nanoscale. The transformation mechanism of the SiC surface to carbon was discussed in detail accounting to the effects of processing parameters (temperature, and composition of the environment), and material parameters (surface conditions, surface chemistry, crystal face, etc.). The characterization of the carbon structures was performed by using scanning electron microscopy (SEM), Raman spectroscopy and transmission electron microscopy (TEM). We compared chlorination of SiC whiskers with wet etching and showed that chlorination revealed the dislocations, while wet etching resulted in pagoda-like 3-D nanostructures upon selective etching of stacking faults (SFs). The difference in etching mechanisms was discussed. We determined the processing conditions for controlled synthesis of carbon structures like graphene, graphite and carbon nanotubes (CNTs) on the surface of [alpha]-SiC wafers by decomposition in low vacuum. CNT brushes grown on SiC showed good mechanical properties and high oxidation resistance. Moreover, we showed that patterns of graphite and catalyst-free nanotubes can be grown simultaneously and directly on a semiconductor SiC wafer. Devices built in this way can be used in applications from sensing to field emission.
The spatial ecology and resource selection of juvenile lemon sharks (Negaprion brevirostris) in their primary nursery areas
Authors:   , Franks Bryan Robert , Spotila James Robert , Gruber Samuel
Published: July 2021

Shark nursery areas have been well studied but information on long-term, finescale movements within nurseries and between nursery areas is lacking. I tracked 47 neonate and juvenile lemon sharks (Negaprion brevirostris) at Bimini, Bahamas (25°44' North, 79°16' West) over three years (2003-2005) within two nursery areas. Using both manual and automated telemetry, I examined the movement patterns and habitat selection of juvenile sharks in the waters surrounding Bimini. Sharks consistently showed a high degree of site fidelity to their natal nursery areas and there was no detectable immigration or emigration between nurseries. Juvenile lemon sharks had small home ranges showing a high degree of reuse of certain areas and there was a positive relationship between home range size and distance from shore with body size. However, sharks from the nursery area that was known to be more environmentally stable showed a stronger relationship between body size and movement patterns. There were consistent differences in movement parameters when comparing similar aged sharks from the two nursery areas. Sharks from the more stable nursery had smaller home ranges were found closer to the mangrove shoreline when compared to the other nursery. Resource selection functions calculated during both the wet and dry seasons from 2003 to 2005 showed that shark locations were most correlated with increased prey biomass and decreased distance to the shoreline. Examining both movement patterns and habitat selection from two distinct nurseries over a long time period demonstrated that juvenile lemon sharks in Bimini utilized the habitat in their natal nursery seemingly to minimize predation risks while maximizing prey availability. Integrated approaches using a variety of long-term data to understand how juvenile sharks utilize nursery areas can significantly improve how essential fish habitat is defined and thereby strengthen conservation and management plans for these species.
System identification of constructed civil engineering structures and uncertainty
Authors:   , Pan Qin , Aktan Ahmet Emin
Published: July 2021

Characterization of constructed civil engineering structures through system identification has gained increasing attention in recent years due to its tremendous potential for optimum infrastructure asset management and performance-based engineering. However, the lack of reliability in system identification, especially when applied to large-scale complex constructed systems, poses a major challenge for its widespread implementation. It is believed that this primarily stems from epistemic uncertainty associated with identification processes, due to unknown or less understood structural behaviors as well as the interaction of the system with its environment. The objective of this thesis is to investigate the effects of epistemic uncertainty on the reliability of identification and to develop solutions to recognize and mitigate these uncertainties. The research which was undertaken included laboratory and field investigation as the primary components. First, a cantilever beam with two test configurations was designed and constructed in the laboratory as a test bed. By comparing different identification scenarios, the impact of modeling uncertainty with epistemic mechanism on the field-calibrated analytical model was evaluated. Feasible techniques were developed to recognize and mitigate significant epistemic modeling uncertainty which controls the test-analysis discrepancy. In applications of system identification on real-life structural systems, the tempo, frequency and spatial incompatibility between detailed finite element model and information contained in test measurements often further complicates the identification process. It was demonstrated through the Henry Hudson Bridge that it was possible to characterize the fundamental behaviors of largescale complex structures by integrating heuristics and conventional techniques. Measurements to assess the adequacy of the field-calibrated models were proposed to ensure that significant epistemic modeling uncertainty was efficiently reduced and critical physical mechaisms was properly conceptualized.
Universal FFT core generator
Authors:   , Shenoy Pranab , Johnson Jeremy Russell
Published: July 2021

This thesis presents a special purpose processor for multi-dimensional discrete Fourier transform (DFT) computation. The processor, called a Universal fast Fourier transform (FFT) processor, is capable of computing an arbitrary multi-dimensional DFT with a fixed number of input points. The processor can be configured to compute different dimensional DFTs simply by rearranging the input data and using a different set of constants, called generalized twiddle factors, throughout the computation. The basic computational process remains the same independent of dimension. The processor does not rely on one-dimensional FFT computation as does the standard approach using the row-column algorithm, but instead utilizes an algorithm called the Dimensionless FFT, whose computation data flow is the same as the FFT algorithm due to Pease. Since the computation performed by the Universal FFT processor is the same as the Pease FFT, an implementation can be obtained by modifying a one-dimensional FFT processor based on the Pease algorithm. The implementation presented in this thesis is obtained in this way from the core generator by Nordin, Milder, Hoe, and Püschel. The core generator from Nordin, Milder, Hoe, and Püschel generates a variety of cores, with various space and time tradeoffs for implementation on field programmable gate arrays (FPGA). The performance obtained is comparable to vendor supplied cores but offers much greater flexibility of design choices with different area and throughput tradeoffs. The resulting Universal FFT core generator can be used to instantiate multi-dimensional FPGA cores with approximately the same performance and area obtained in the one-dimensional case by Nordin, Milder, Hoe, and Püschel.
Dance/movement therapy and autistic disorder
Authors:   , Cornman Douglas E. , Goodill Sherry W.
Published: July 2021

Dance/Movement Therapy (D/MT) has been a successful intervention in thetreatment of autistic children. Depending on the needs of the child, intervention may beindividual (therapist and child) or include members of the child's family. In the past, mostfamily D/MT intervention has focused on the mother/child dyad since this has traditionallybeen the primary care giving relationship. In an effort to document the importance of thepaternal influence on the development of an autistic child, this study examined therelationship between a father and his autistic son and the effects that D/MT had on thatrelationship. The following three hypotheses were proposed: 1) D/MT would promotepositive change in the relationship by expanding both the father's and son's movementrepertoire, thus providing options for more successful interaction; 2) the son's level offunctioning would increase in correlation with this positive change; and 3) the father'sstress level concerning both his relationship to his child and his own parenting style woulddecrease based upon his gaining an understanding of their relationship on a movementlevel. The subjects participating in this study were a thirty-seven-year-old father, who isdiagnosed with degenerative Cerebral Palsy, and his three-year-old autistic son. The dyadreceived six weekly D/MT sessions. They were rated pre- and post- D/MT intervention. The father's relationship to his son, the son's relationship to his father, and the father/sonrelationship was rated on the Nonverbal Assessment for Family Systems scale (Dulicai,1977), the child's relationship to his father was rated on the Relationship to an Adult,Communication, Drive for Mastery, and Body Movement scales of the Behavioral RatingInstrument for Autistic and Other Atypical Children (Ruttenberg, Kalish, Wenar, & Wolf,1977 & Ruttenberg, Wolf-Schein, & Wenar, 1991) and the father's stress levels were ratedby the Parenting Stress Index (Abidin, 1986). Results at post-test supported the study's initial hypotheses. Both the father and sondisplayed a broader movement repertoire which increased their interactional options. Theson demonstrated increased skill in each of the four scales of the BRIAAC. Finally, thefather's overall level of stress concerning his son and his parenting style decreased. Thepositive results of this study suggest that fathers are important participants in the treatmentof autistic children. They also suggest that using the design of this study with a largersample size and research concerning the father/child relationship in general is warranted.
Mobilizing to empower and restore
Authors:   , Harris David Alan , Goodill Sherry W.
Published: July 2021

This literature-based study engages a revisioning of dance/movement therapy ascommunity-based practice, capable-through a program emphasizing restoration andempowerment-of responding effectively to the needs of children affected by war andorganized violence. Half of the world's 35 million refugees are children, and most comefrom the developing world. For these children, experiences of uprooting, displacement, poverty, and repression exacerbate those of exposure to the extreme stressors of armed conflict. A risk factor vs. protective factor analysis of stress and resilience is applied toward assessing the multiple dimensions of children's vulnerability and strength in the face of atrocity and deprivation. Given a preponderance of evidence to support adifferential association between exposure to stressors in such contexts and subsequentemotional or psychological disturbance, investigations of factors conducive toadaptational outcomes are highlighted, as these may provide foundation for preventiveinterventions. Issues of cultural difference between children from the developing world andtherapists from the developed are explored, and such constructs as "trauma" discussedwith reference to the ethnocultural relevance of posttraumatic stress disorder and itsalternatives. Ethnographic studies of the construction of identity in holistic, collective-or "sociocentric"-cultures are introduced, and complemented with insights from psychological investigators and therapists from the developing world. The theory that rituals hold transformative potential for societies disrupted by the forces of armed conflict is advanced, and shown relevant to therapeutic objectives among war-affected populations for whom the restoration of sociality may be a principal need. Interventions that integrate Western intrapsychic and "traditional" techniques are deemed especially germane to dance/movement therapy, given the modality's predication on an integral connectedness of mind and body. A sample "traditional dance"-based program for a resilient group of war-affected, resettled refugee youth from the Southern Sudanillustrates a re-imagining of such integrative psychotherapeutic intervention. This project, informed by an understanding that social reintegration is pivotal to mental health in sociocentric groups, recasts the dance/movement therapist as a community organizer focused on empowering as well as restoring. An Inventory of Psychosocial-Cultural Interaction is provided as a tool for the development of culturally relevant interventions with such groups.
On the organization of neurophysiologic processes and the integration of conscious and unconscious perceptions in dance/movement therapy
Authors:   , MacCallum Virginia Elaine , Goodill Sherry W.
Published: July 2021

This study explores the relationship between the organization of neurophysiologicprocesses and the integration of conscious and unconscious perceptions in dance/movementtherapy. The view is proposed that processes of organization and perception form a singlegestalt: change in one produces a shared change in the other. The implications of this view are discussed in terms of the capacity of dance/movement therapy to access the reciprocal nature of this relationship and effectively promote an individual's psychic and organic health. The literature examines the interrelationship of perceptual and organizational processes in terms of psychic, organic and motoric expression. Perspectives from the fields of psychology, hypnotherapy, neuroscience, and quantum physics are considered in relationship to dance/movement therapy theory. A theoretical integration of the literature emphasizes the view that the basis of allcognitive, emotional, and physical expression is the neurologic processing of patterns ofenergy. The essential role of movement in every perceptual-organizational event isunderscored. From these understandings, this thesis submits that dance/movement therapyaccesses states of healing and adaptation within the nervous system by engaging themovement potential of the individual on multiple levels and promoting the consciousrealization of the interrelationship between perceptual and organizational processes.
Improved performance for network simulation
Authors:   , Willman Bryan J. , Weber Steven P.
Published: July 2021

Over the course of designing and implementing two discrete event simulators, the commercial simulator packages CSIM and DesmoJ were leveraged to allow for rapid development of both wired and wireless network models. However, the two resulting simulators demonstrated poor scalability due to the use of multi-threading to maintain state for simulation elements. By using a simple single-process discrete event simulation engine, the running-time showed a marked decrease when compared to multi-threaded simulators. In one case study, we simulate a simple two-link MPLS network which employs two congestion control mechanisms for inelastic traffic, namely preemption and adaptation. Performance metrics measured include: the per-class blocking probability, customer average fraction of time streams travel on the preferred path, customer average fraction of time at the maximum subscription rate, the customer average rate of adaptation, and the time average rate of preemption. We compare the performance of preemption and adaptation individually and collectively against the base case where neither congestion mechanism is used. At the cost of increased number of rate adaptations and preemption events for a range of regimes, we show that the combined use of preemption and adaptation improves the quality of service and alignment of high priority traffic while increasing the effective network capacity. As a performance enhancement to the simulator developed to conducted these experiments, we switched to a single-process discrete evnt simulation engine in place of multi-threaded simulator. We note a large improvement for the running time as the simulation time and capacity increase. A second case study was conducted on a wireless simulator. In an effort to simplify the simulator and improve performance we again moved from a commercial thread-based simulator (CSIM) to a single-process discrete event simulation engine. Results of the runningtime vs network size for the single-process simulator showed a constant-time improvement over the thread-based simulator. To further improve performance, a complementary technique known as model abstraction is also applied. Model abstraction is a technique that reduces execution time by removing unnecessary simulation detail. In this thesis we propose three abstractions of the IEEE 802.11 protocol. The Goodput Ratio vs Transmission Power and End-to-end delay vs offered load performance metrics are compared against the OPNET commercial simulator.
Carbothermal synthesis of coatings on SiC fibers
Authors:   , Chen Linlin , Gogotsi Yury
Published: July 2021

Four kinds of protective coatings FFcarbide derived carbon (CDC), boron nitride (BN), Al-O-N and BN doped Al-O-N (BAN) have been successfully synthesized on the surface of SiC fibers on the target to enhance the mechanical properties and oxidation resistance of the coated SiC fibers for the application as the reinforcements in the Ceramic Matrix Composites (CMCs) in the high temperatures. First of all, CDC coatings have been uniformly produced on Tyranno ZMI SiC fibers with good thickness control within nanometer accuracy by the chlorination in the temperature range of 550-700°C at atmospheric pressure. Kinetics of the carbon coating growth on the fibers has been systematically studied and thus a good foundation was set up for the further coating synthesis. BN coatings have been synthesized on the surface of SiC powders, fibers and fabrics by a novel carbothermal nitridation method. Non-bridging has been achieved in the BN-coated fiber tows by the nitridation in ammonia at atmospheric pressure in a temperature below 1200°C, which is lower compared to the traditional BN synthesis method and does not cause the degradation of the coated-fibers. BN coatings on the carbon nanotubes have also been formed and unlike the common methods, no additional dopant (such as metal catalyst) is introduced into the system during the BN coatings syntheses, thus the contamination of the final product is avoided. A novel Al-O-N coating has been explored with the most impressive point is that a more than 65% improvement in the tensile strength (up to ~5.1GPa) and a three-time increase in the Weibull modulus compared to the as-received fibers are resulted by the formation of 200nm Al-O-N coating on the SiC fibers. It exceeds the strength of all other small diameter SiC fibers reported in the literature. Furthermore, BAN coating has also been produced on the surface of SiC fibers and about 20% enhancement in mechanical strength is achieved compared to that of the original fibers. Oxidation experiments of the SiC fibers with four kinds of coatings under 1000°C and 1200°C in air have been carried out and better oxidation resistance of the coated fibers are presented compared to the as-received fibers. In summary, exploration of various coatings synthesis for the SiC fibers has been successfully conducted in this work. The coating material suitable for the SiC fibers should be chosen properly according to its specific application in the CFCCs and well thickness-control to meet the corresponding requirements.
Synthesis, characterization, and application of polyethylene glycol modified insulin for oral delivery using complexation hydrogels
Authors:   , Tuesca Anthony D. , Lowman Anthony M.
Published: July 2021

Therapeutic proteins and peptides represent a major area of research in current pharmaceutical and biotechnology companies. Due to their inherent instability, the vast majority of these drugs require parenteral administration. Such is the case for as many as 6 million patients in the United States who use insulin in the treatment of diabetes mellitus. Oral insulin delivery would is a highly desirable alternative method of administration, though it continues to be an elusive target due the enzymatic digestion of insulin and low levels of absorption from the gastrointestinal tract. Hydrogel polymers have shown promise as potential carriers for oral insulin delivery. In particular, a pH responsive hydrogel composed of poly(methacrylic acid-g-polyethylene glycol), P(MAAg- EG), has shown the ability to protect insulin from enzymes in the gastric environment and release in small intestines. It was also able to induce a hypoglycemic effect in vivo when delivered to isolated ileal segments in rats. However, this material has not shown similar potential for oral protein delivery of other model drugs. To date, the unique interaction between P(MAA-g-EG) and insulin, which give it such potential for oral delivery, are not completely understood. The focus of this research is to investigate how P(MAA-g-EG) hydrogels interact with insulin and to improve upon current designs for oral insulin delivery. An attempt is made to correlate the structure and chemistry of the hydrogel to its interaction with insulin over the pH range exhibited by the gastrointestinal tract in vitro. Further insight is gained by observing the interaction of the hydrogel with insulin-like proteins including insulin glargine, an insulin analog, and polyethylene glycol (PEG) modified insulin. The PEG-insulin conjugate is synthesized and characterized to maintain the bioactivity of the protein, which is confirmed in vivo using intravenous and subcutaneous administration in rats. Finally, the proposed system is tested using an in vivo model in Sprague Dawley rats and related to the potential application of P(MAA-g-EG) to deliver insulin and PEG modified insulin for the treatment of diabetes.
Nanoscale hierarchical phase behavior of liquid crystalline block copolymers
Authors:   , Tenneti Kishore Kumar , Li Christopher Y.
Published: July 2021

Self assembly of block copolymers (BCPs) is a bottom-up technique for manufacturing nanostructures with precision and efficiency. Hierarchy in structure and functionality can be achieved in BCPs by combining two classes of soft matter (BCPs and liquid crystalline polymers (LCPs)), which form ordered structures at different length scales, into a single phase system. Ensembles of nanostructures ranging from few nanometers to micrometers can be achieved. Three methods that have varying flexibility in terms of structure and functionality have been used to introduce LCPs into BCPs. The first part of the research focused on the characterization of phase structures of mesogenjacketed LCPs that form rigid macromolecular columns within which the mesogens were aligned at an angle to the polymer backbone. A series of samples were investigated and the influence of molecular weight (Mn) and volume fraction (f) on the overall phase behavior was studied in both low Mn and high Mn systems and symmetric/asymmetric systems. After establishing the phase behavior of MJ-LCBCP system, the second part of the thesis was focused on changing the diameter and surface chemistry of the macromolecular columns. The diameter was increased by changing the three-ring mesogen into a five-ring mesogen and the surface chemistry was altered by introducing alkyl tails along to the mesogens. This led to the formation of core-shell MJ-LCBCP system formed by the mesogenic core and alkyl tails. Within this system, the influence of f on the final phase morphology was studied in symmetric/asymmetric samples. The final part of the thesis was focused on the influence of improving the flexibility of the mesogen. Accordingly, both SC-LCBCP and H-bonded LCBCPs were studied. In the SCLCBCPs, 12 carbon spacers were used to decouple the interactions between the mesogen and polymer backbone whereas in the H-bonded system, interactions between terminal - OH group of mesogen and nitrogen of the pyridine block were exploited to achieve the H-bond. The influence of fLC on the final phase structures was studied in both these systems. Detailed structural characterization results are presented that emphasize the unique phase behavior of these advanced materials.
Effect of decellularization protocol on the mechanical behavior of porcine descending aorta
Authors:   , Fitzpatrick John Charles , Capaldi Franco M.
Published: July 2021

Diseases of the human vascular system are the leading cause of death and hospitalization in the United States. Surgical treatments for vascular complications, such as bypassing or replacing occluded arteries, are complicated by the lack of healthy tissue available for grafting. The feasibility of using xenografts and allografts has recently been demonstrated as an alternative to DACRON and expanded polytetraflouroethylene (ePTFE) biomaterials, which lose patency after a short time. Through decellularization procedures, vascular tissue can be reduced to a sterilized scaffold, seeded with the transplant recipient's endothelial cells, and implanted with a low risk of rejection. Enzymatic-detergent treatments used to lyse vascular smooth muscle cells (VSMCs) may use deoxycholic acid, TritonX-100/EDTA, or SDS, which disrupt cellular adhesion integrins. These treatments may significantly impact the mechanical properties of the extracellular matrix scaffold and contribute to graft compliance mismatch. Native and decellularized longitudinal arterial tissue samples cut from similar crosssections were tested in uniaxial tension to observe changes in mechanical behavior resulting from decellularization protocols published in Rieder et al., (2004), Schaner et al., (2004), and Bader et al., (1998). Rectangular parellepiped arterial wall samples were analyzed as membranes in terms of engineering stress. Experimental uniaxial stressstretch data were fit to a modified form of the Yeoh rubber model by least-squares curve fitting. The Yeoh parameters generated by the least-squares fit for native and decellularized sections were then assessed for statistical significance using a paired t-test analysis. The TritonX-100/EDTA and 0.075% SDS treatments resulted in highly variable mechanical changes and did not effectively lyse VSMCs, as determined by H&E staining. The 0.25% deoxycholic acid treatment reported in Rieder et al., (2004) showed minimal changes in mechanical behavior and effectively lysed VSMCs. The data suggests a 0.25% deoxycholic acid treatment has minimal effects on mechanical properties of aortic tissue while effectively lysing VSMCs and is therefore a more effective option than TritonX-100/EDTA and SDS treatments for the preparation of xenografts and allografts.
Blood model plasma separation in a microfabricated PDMS device exploiting capillary action driving forces
Authors:   , Hinkle Tyler Nathaniel , Papazoglou Elisabeth S.
Published: July 2021

The goal of this thesis was to successfully design and fabricate a point-of-care microfluidic device that effectively separates plasma from a blood model without external pumping or other applied driving forces. There is currently no commercially available or published microfluidic device that accomplishes blood plasma separation without pumping or externally applied driving forces. This pump-free device will decrease size and cost while increasing the number of possible applications. The final separated plasma could be further used for detection of biomarkers linked to specific diseases and conditions through tailored antibody based assays by future researchers. The separation device was fabricated using known lithography masking techniques to create a negative to be molded in PDMS using standardized molding fixtures to ensure device uniformity. Fluid flow through the device was promoted by using a plasma-free hydrophilic surface treatment greatly reducing the contact angle of PDMS from about 90 degrees to about 50 degrees. The effectiveness of this device was tested and validated using water emulsions of polystyrene beads adjusted to a viscosity equivalent to that of blood (4.0 +/- 0.5 cP) to represent a simple blood model. The final device is able to separate the model plasma cells (1-3um diameter) from the red (3-8um diameter) and white (8-12um diameter) blood cells with greater than 85% efficiency with a low filtration dead-volume of less than 10ul.
Chitosan and carboxymethyl chitosan as catalyst matrix materials
Authors:   , Laudenslager Michael John , Schauer Caroline L.
Published: July 2021

Chitosan, a polysaccharide derived from crab and shrimp shells, was investigated as a matrix material for catalytic platinum, gold, and silver nanoparticles. Not only is chitosan able to stabilize nanoparticles, it is able to reduce metal ions to a zero valent state while controlling nanoparticle growth. The size, morphology, and catalytic activity of nanoparticles produced were examined in chitosan, and carboxymethyl chitosan (CMC), a chemically modified form of chitosan. Carboxymethyl chitosan is reported to have a higher metal ion binding capacity, but has not been previously tested as a support material for catalytic nanoparticles. Nanoparticles were characterized through UV-vis absorbance and transmission electron microscopy. Platinum nanoparticles have a narrow size distribution with an average size of 3.5 nm while gold and silver have much broader size ranges with average particle sizes of 23 nm and 7 nm respectively. The size and morphology of the nanoparticles did not vary significantly between the two polymers for each type of catalyst. However, a higher aggregation rate was observed in CMC. Nanoparticles supported on chitosan flakes were shown to be active, reusable catalysts. The catalytic activity of chitosan supported nanoparticles was monitored through UV-vis absorbance of the reduction of 4-nitrophenol in the presence of sodium borohydride. The characteristic absorbance peak of 4-nitrophenol is directly proportional to its concentration. By using an excess of sodium borohydride, pseudo first order rate kinetics can be assumed. Rate constants show that all three types of nanoparticles are catalytically active with silver nanoparticles having the highest rate constant followed by platinum and gold. The three catalysts did not change in activity after several runs when supported in chitosan; however, carboxymethyl chitosan supported catalysts were not appreciably retained by the matrix material.
A prototypical self-optimizing package for parallel implementation of fast signal transforms
Authors:   , Chen Kang , Johnson Jeremy Russell
Published: July 2021

This thesis presents a self-adapting parallel package for computing the Walsh-Hadamard transform (WHT), a prototypical fast signal transform, similar to the fast Fourier transform. Using a search over a space of mathematical formulas representing different algorithms to compute the WHT, the package finds the best parallel implementation on a given shared-memory multiprocessor. The search automatically fins the best combination of sequential and parallel code leading to effective granularity, load balance, and cache utilization. Experimental data are presented in the thesis showing the performance of the package on four different architectures. Results are also presented showing the optimizations required to obtain nearly linear speedup on these sample symmetric multiprocessors.
An investigation of the role of shame and attributions in adjustment following child physical abuse
Authors:   , Smith Susan L. , Kloss Jacqueline D.
Published: July 2021

Child physical abuse (CPA) has been associated with a number of negative outcomes (Cerezo-Jimenez & Frias, 1994; Cicchetti & Toth, 1995; Deblinger, McLeer, Atkins, Ralphe, & Foa, 1989; Kolko, 1996; Runyon & Kenny, 2002). However, not every child who experiences physical abuse exhibits significant maladjustment. A prominent model has been proposed in the sexual abuse literature attributing variability in adjustment to cognitive (attributions) and emotional (shame) processing (Feiring, Taska, & Lewis, 1996). The present study was a pilot examination of the relationship between variables in this model within a CPA population. Data from 64 children between the ages of 7 and 17 presenting for treatment subsequent to confirmed or suspected CPA was extracted from a research repository for analyses in the present investigation. As has been demonstrated in previous literature, more self-blame was associated with higher rates of depression and PTSS among this sample. A significant relationship between severity of abuse and adjustment was not detected. Furthermore, self-blaming attributions remained significantly related to negative adjustment, even when controlling for severity of abuse. The present study also supported a relationship between the experience of shame and negative adjustment in children who have experienced physical abuse; however, shame did not mediate the relationship between attributions and adjustment in this CPA sample. Given the smaller than projected sample size and limited power, data collection is ongoing, and analyses of the present investigation will be re-run in the future when a more complete data-set has been obtained.
A prospective test of predictors of physical activity in freshman college women using a path analytic method
Authors:   , Tappe Karyn Andrea , Lowe Michael R.
Published: July 2021

Physical activity levels decrease dramatically from childhood to adulthood, and only a minority of adult Americans meets the minimum recommendations for regular exercise. It therefore appears important to intervene with young people to encourage them to continue leading an active lifestyle rather than settling into a sedentary lifestyle common among adults. The first step towards encouraging such activity is to understand the reasons that some individuals adopt an active lifestyle while others do not. The present study examined young adult women entering their first year of college and evaluated the ability of a number of individual psychological variables to predict exercise behavior over several months. The variables explored included those comprising the Theory of Planned Behavior, past exercise behavior patterns, personality characteristics, physical self-efficacy, and change in emotional affect after a single bout of moderate exercise. The participants in this study were asked to walk on a treadmill for 10 minutes (for the purpose of measuring affective change with physical activity), self-report their physical activity over three days, complete a number of questionnaires, and, two to five months later, again self-report their recent exercise behavior. Path analysis was used to evaluate the predictive value of these variables for current and future exercise behavior. Eighty-two women provided data at time 1 and 53 provided data longitudinally. Results indicated that, cross-sectionally, intention and past exercise behavior predicted current exercise behavior most strongly. Longitudinally, in part due to low statistical power, many of these relationships diminished and only current exercise behavior and affect change after walking were independent predictors in the confirmatory model; an exploratory model suggested that personality and intention could also be a significant direct independent predictor of behavior. These differential cross-sectional and longitudinal findings suggest that the women may have been less tuned into internal predilections early in their freshman year, but that these predispositions became more influential later. Past behavior predicted later behavior as expected, but over a limited time span. These findings raise intriguing questions about the changing nature of the early college experience and an individual's changing awareness of environmental versus internal cues for behavior.
Development of a genetic algorithm-correlation analysis (GA/CA) program for classification of chemical compounds using mass spectral data
Authors:   , Li Fang , Owens Kevin Glenn
Published: July 2021

A semi-automatic computer program GA/CA (genetic algorithm/correlation analysis) is developed in this project for the classification of chemical compounds using mass spectra. The program uses a genetic algorithm as the optimization method and correlation analysis as the evaluation method. In performing a classification, the GA/CA program searches for a group of mass peaks that best discriminate the substructure of interest using the mass spectra of known compounds, and then uses the search results on unknowns for prediction. The GA/CA program is able to perform the classification using mass spectra, neutral loss spectra and parent loss spectra, as well as perform data preprocessing techniques, such as intensity exponent scaling and thresholding. The GA/CA program is successfully used in two tests using library spectra: classification of lower aromatic compounds, and chlorine containing compounds. The chromosomes developed by the GA/CA program showed 100% prediction accuracy for the test compounds in both classification experiments. In the classification of carbamates, the best chromosomes developed by the GA/CA program result from use of the neutral loss spectra, which show a prediction accuracy of 93% on the test set. The prediction accuracy increased when the individual results obtained by use of mass spectra, neutral loss spectra and parent loss spectra are combined together. The GA/CA was also used for identification of the metabolites of the carbamate methyl thiophanate from LC-MS/MS data. Chromosomes were developed by the GA/CA program using spectra collected in the laboratory. The results showed that the GA/CA program identified three of the known metabolites correctly and one metabolite incorrectly. The GA/CA program also identified another possible metabolite that was not identified in a previous metabolic study. The GA/CA needs to be rewritten as a completely automatic program so that it can handle a larger number of spectral data and run for a large number of generations.