>Magister Scientiae - MSc / Applications of electrochemiluminescent conjugated polymers offer promising solutions in addressing the problem of light emitting devices. However, the challenging problems that hamper their application in light emitting devices are loss of signal due to diffusion of the electrochemiluminescence (ECL) reagent out of the detection zone, limited ability to repeatedly cycle an individual luminophore and high reagent consumption. In this work, the main objective was to produce conducting polymers with enhanced electrochemiluminescence by tuning the properties of the polymer itself. The electrochemical and photophysical properties of films of polyaniline (PANI) and poly(8-anilino-1- naphthalene sulfonic acids) (PANSA) synthesized through electro- and chemical polymerization methods were also investigated. The electrosynthesis of PANSA undoped and doped with anthracene sulfonic acid (ASA), 1,2-naphthaquinone-4-sulfonic acid (NSA) and carbon nanotubes (CNT) in acid medium was investigated and the cyclic voltammograms (CV) showed the growth of the polymer during polymerization. The CV multiscan characterization displayed that the growth of the polymer was dependent of the scan rate and the three redox couples were observed as indicative of the three redox states of typical polyaniline and its derivatives. The results also showed that the peak currents were diffusion controlled and the electron charge transport coefficient (De) of the electrosynthesized polymers was found to range between 10⁻⁸ and 10⁻⁹ cm² s⁻¹ for PANSA, PANSA-ASA, PANSA-NSA and PANSA-CNT. The De value indicates that the movement of electrons along the polymer chain was averagely fast. The transmission electron microscopy (TEM) was used to investigate the electronic morphology of the polymers and the TEM images showed an intertwinement of tubings which aggregate into a ring with a mixture of tubings and plastic sheets. The chemical synthesis of PANI, PANSA and PANI-NSA was carried out by using monomers analine, 8-anilino-1-naphthalene sulfonic acid, and aniline with 1,2- naphthaquinone-4-sulfonic acid, respectively, using oxidants. All chemically synthesized polymers exhibited quinoid and benzoid bands typically see in polyaniline FTIR and Raman spectra confirmed the successfully formation of polymers. The CV characterization of these polymers showed distinctive redox peaks. This proved that the polymers were electroactive, conductive and exhibited reversible electrochemistry. The De of the electrosynthesized polymers was found to be ~10⁻⁵ cm² s⁻¹ for chemically synthesized polymers. The electric conductivity measurement showed to increase from 10⁻⁴ to 10⁻² when aniline was polymerized with NSA dopant, this might be related to the process of electron transfer from dopant to polymer. Scanning electron microscopy for external morphology showed that the polymers were made of different nano- rods polymeric structures. Photophysical properties of electro- and chemically synthesized PANSA and PANI were investigated through UV-vis absorption, fluorescence behaviour, and lifetime. The UV-vis absorption spectra of these polymers showed that they exhibited absorption bands corresponding to the polyemeraldine redox state of typical polyaniline. The effect of dopants resulted in the increase in solubility of the polymers with a small shift of absorption bands due to incorporation of dopants in to the backbone of the polymer. The fluorescence emission spectra of the electrochemically synthesized PANSA with and without dopants were observed to be similar and mirror image of the excitation spectra and corresponding to the electronic band of the benzoid ring in the polyemeraldine form confirming that the fluorescing molecule in these polymers were the benzoid rings. However, the emission spectra of the chemically synthesized PANSA and PANI were different to excitation spectra due to loss of symmetry upon excitation. The effects of chemically synthesized PANI, PANSA and PANI-NSA addition on the photophysical properties of [Ru(bpy)₂(picCOOH)]²⁺.(ClO₄⁻)₂) were investigated in order to understand the interaction of polymer and [Ru(bpy)₂(picCOOH)]²⁺.(ClO₄⁻)₂. The analysis revealed that the presence of polyaniline and its derivatives enhanced the [Ru(bpy)₂(picCOOH)]²⁺.(ClO₄⁻)2 absorption band, photoluminescence and fluorescence lifetime. The enhancement observed from interaction of [Ru(bpy)₂(picCOOH)]²⁺.(ClO₄⁻)₂ with polyaniline and its derivatives might be due to the excited state electron transfer from the PANI and PANSA excited state to the [Ru(bpy)₂(picCOOH)]²⁺.(ClO₄⁻)₂. It was further demonstrated in this work that it is possible to form polyaniline and PANSA doped with [Ru(bpy)₂(picCOOH)]²⁺.(ClO₄⁻)₂ films on ITO electrode using potentiostatic growth method to favour ECL production. The results showed that all films generated ECL in the presence of Tripropylamine (TPA) as a co-reactant and their emission properties depend on time used to prepare the film. The enhancement of ECL signal was due to a positive electron transfer from the conducting polymer (PANI and PANSA) to [Ru(bpy)₂(picCOOH)]²⁺.(ClO₄⁻)₂ complex. The results highlighted the potential of these polymeric luminophores usage in the manufacturing of the ECL devices.

The aim of this study is the production of a nanofibrous electroactive mat and the investigation of its potential use in tissue engineering, and more specifically for wound dressing purposes. The limitations regarding electrospinnability of the conducting polymer will be identified and addressed and the factors related to its biological properties will be evaluated. To this end, conducting polymer, polyaniline (PANI) was chosen as the electroactive component and blend electrospinning was identified as the most suitable method to produce continuous nanofibres containing PANI. Various biocompatible polymers and solvent systems were investigated for their suitability to assist in electrospinning and PEO (polyethylene oxide) and CH (chitosan) were chosen as carrier polymers for blend electrospinning of PANI. Consequently, CSA (Camphor-10-sulfonic acid (β)) doped PANI/PEO and CSA doped PANI/CH conducting nanofibrous mats were produced by electrospinning. The electrospinning windows for both blends were determined by using full factorial experimental designs. The combined effects of the humidity, voltage and flow rate on the fibre morphology and diameter were examined for both blends, demonstrating that the ambient humidity is the critical factor affecting the electrospinning process and determining the electrospinning window for a conducting polymer. Low humidity favors the formation of defect free fibres while high humidity either hinders fibre formation or causes the formation of defects on the fibres. In the case of PANI/PEO blends, different levels of PANI doping were investigated, and high level of doping with CSA was found to lead to the formation of crystalline structures. Data fitting was used to explore the behavior of conducting polymers using the case of PANI/PEO electrospinning and very good agreement between experimental and theoretical predictions was obtained for only a limited range of experimental conditions, whereas deviation was observed for all other sets of conditions. In the case of PANI/CH, the effect of different ratios of conducting polymer in the blend (0:1, 1:3, 3:5 and 1:1) was examined, as for the electrospinnability, resulting 3 nanofibrous morphology, mat contact angle, electrical conductivity, antibacterial activity and cellular biocompatibility. The incorporation of PANI in the electrospinning blend, affected the electrospinnability of the solution, making it more susceptible to RH deviations, and contributed to the decrease of nanofibre diameter. Higher PANI content was found to result in more hydrophobic and more conducting mats. The method that was used to stabilize the PANI/CH mats was also found to affect antibacterial activity and conductivity. The produced blend mats, exhibited antibacterial activity which was higher against Gram positive B. subtilis and lower against gram negative E. coli. The cellular biocompatibility was assessed with human osteoblasts and fibroblasts, in terms of cell proliferation rate as well as cell attachment and morphology. Cells of both cell lines adhered well and showed good growth rates on nanofibrous substrates of all blend ratios when compared to standard tissue culture plastic. Finally, amongst the PANI containing mats, the one of 1:3 PANI:CH ratio, was identified as the best to support osteoblast and fibroblast cell proliferation when compared to the pure chitosan.

abstract: By examining the cognitive mechanisms behind human memory, the author hypothesizes that instrumental conductors can more quickly and effectively internalize music scores. With this theory, conductors could offer more informed and nuanced communications to their ensembles. Furthermore, these ideas could be incorporated into how conducting is taught to younger students by cultivating a more in-depth understanding of the music being studied. This research paper surveys current trends in cognitive science related to the interactions of long-term memory (LTM) and short-term memory (STM) concerning score study and memorization employed by instrumental conductors. The research is divided into three sections, beginning with an examination of the key literature from the field of cognitive science. It continues with an overview of current musicological research and applications and finally concludes with a review of current instrumental conducting pedagogy that include discussions of memory. Moreover, recommended steps and a potential framework to incorporate cognitive science research into future conducting pedagogies are further outlined. The primary cognitive theory of focus is the Working Memory Theory of Alan Baddeley and Graham Hitch. / Dissertation/Thesis / Doctoral Dissertation Music 2017

abstract: Scattering from random rough surface has been of interest for decades. Several methods were proposed to solve this problem, and Kirchho approximation (KA) and small perturbation method (SMP) are among the most popular. Both methods provide accurate results on rst order scattering, and the range of validity is limited and cross-polarization scattering coecient is zero for these two methods unless these two methods are carried out for higher orders. Furthermore, it is complicated for higher order formulation and multiple scattering and shadowing are neglected in these classic methods. Extension of these two methods has been made in order to x these problems. However, it is usually complicated and problem specic. While small slope approximation is one of the most widely used methods to bridge KA and SMP, it is not easy to implement in a general form. Two scale model can be employed to solve scattering problems for a tilted perturbation plane, the range of validity is limited. A new model is proposed in this thesis to deal with cross-polarization scattering phenomenon on perfect electric conducting random surfaces. Integral equation is adopted in this model. While integral equation method is often combined with numerical method to solve the scattering coecient, the proposed model solves the integral equation iteratively by analytic approximation. We utilize some approximations on the randomness of the surface, and obtain an explicit expression. It is shown that this expression achieves agreement with SMP method in second order. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2017

Neste trabalho, realizamos um estudo da dependência da condutividade elétrica dc ( ), com a dopagem (tempo de exposição ao ácido clorídrico de (0 a 6 horas), temperatura (80 T 300K) e campo elétrico (E) em filmes auto-sustentáveis de polianilina. As amostras foram metalizadas com ouro em ambas as faces e as medidas realizadas utilizando-se o método de duas pontas. O pó utilizado nos filmes foi sintetizado quimicamente através da mistura da anilina com ácido clorídrico, a qual foi adicionada uma segunda solução de peroxidissulfato de amônio e que após desdopagem com hidróxido de amônio, obteve-se a base esmeraldina, esse produto foi dissolvido em N-Metil Pirrolidona possibilitando a obtenção dos filmes pelo método casting e posteriormente dopados por imersão em solução de ácido clorídrico em níveis desejados. Para um curto tempo de exposição ao ácido clorídico (menos de 30 minutos) observamos um rápido crescimento da condutividade com o aumento da dopagem. Para tempos mais longos a condutividade tende a saturação. Da análise da condutividade em função da temperatura obtivemos que ~ exp(T(-1/4)) consistente com o modelo de \"Saltos de Alcance Variável\" proposto por Mott. Nesse modelo a condução ocorre através do tunelamento assistido por fônons entre estados eletrônicos localizados. Se os estados são muito localizados um elétron só poderá saltar para o estado mais próximo, e assim a condutividade será proporcional ao fator de Boltzmann. Se a localização é menos intensa , um elétron pode saltar para sítios onde a energia de ativação é menor mas que estão situados mais distantes do que os primeiros vizinhos, ou seja, a condução ocorrerá por saltos com alcance variável. / In this work, we accomplished a study of the dependence of the dc electrical conductivity ( ), with the doping level (time of immersion of the film into the hydrochloric acid - 0 t 6 hours), temperature (80 T 300K) and electric field (E) in polyaniline thin films. The electric contacts to the samples were obtained using gold deposited in both faces and the measurements have been done using the method of two points. The powder used in the films was synthesized chemically through the mixture of the aniline with hydrochloric acid. A second solution of ammonium peroxidissulfate has been added to the mixture and after that the same has been treated with ammonium hydroxide. The emeraldine base so obtained has been dissolved in N-Methyl-2-pyrrolidinone to be used to produce the films by the method of casting. Later on the films have been doped by imersion with hydrochloric acid in wanted levels. For a short time of immersion into hydrochloric acid (less than 30 minutes) we observed a fast growth of the conductivity with the increase of the doping level. For longer times the conductivity tends to the saturation. Analyzing the conductivity as a function of temperature we obtained that ~ exp (T(-1/4)) consistent with the model of Variable Range Hopping proposed by Mott. In that model the conduction happens through the tunneling of carriers assisted by phonons between localized electronic states. If the localization is very strong, the carrier can only jump to the nearest state, and the conductivity will be proportional to the Boltzmann factor. If the location is less strong, a carrier can jump to sites for which the activation energy is smaller but which can reside further way. As a result we have conductivity with variable range hopping.

Filmes de politiofeno foram eletroquimicamente depositados em diversos substratos eletródicos em meio aquoso fortemente ácido e as características dos materiais formados foram estudadas através de técnicas voltamétricas, espectroscópicas (FTIR e UV-Vis. e raios X) e por microscopia eletrônica de varredura. As propriedades foram comparadas com as de filmes sintetizados em meio não-aquoso concluindo-se que o material produzido em meio aquoso mostra-se mais adequado para a aplicação como suporte de partículas eletrocatalisadoras, por sua maior atividade eletroquímica, homogeneidade e estabilidade. Foram então incorporadas partículas de Pd e Pt que foram investigadas quanto a ação catalítica frente as reações de oxidação de hidrogênio (ROH) e redução de oxigênio (RRO) em ácido sulfúrico 2,0 M. Os materiais produzidos foram primeiramente caracterizados através de técnica de absorção de raios X, tendo sido observada a formação de aglomerados de partículas bastante pequenas que não alteram seu estado de oxidação com a mudança do potencial eletródico. Verificou-se que ambos os catalisadores apresentam uma certa atividade inicial frente a ROH, mas o desempenho não é estável devido à ocorrência de processos degradativos da cadeia polimérica. Por outro lado, observou-se que os filmes contendo Pt apresentam elevada atividade catalítica frente a RRO, substancialmente maior que a de filmes contendo Pd. O mecanismo da reação mostrou-se dependente da natureza do catalisador, sendo também influenciado pelo contato com o filme polimérico. Para a Pt em contato direto com o eletrólito, a reação ocorre com envolvimento de 4 elétrons e com formação de água como produto final. Para o caso em que as partículas de Pt são recobertas por politiofeno, verifica-se a participação do peróxido de hidrogênio como intermediário, sendo que somente uma certa fração do mesmo reduz-se para formar água. No caso do Pd, o processo leva à formação de peróxido de hidrogênio em baixos sobrepotenciais, que depois é reduzido, com formação de água, em sobrepotenciais mais elevados. / Polythiophene films were electrochemically grown on several electrode substrates from strong acid aqueous solutions, and the characteristics of the materials investigated using cyclic voltammetry, FTIR and UV-Vis spectroscopies, and scanning electron microscopy. Compared to the materials prepared in non-aqueous media, the polymer synthesized in aqueous media shows more adequate characteristics for using as support for electrocatalytic particles, because of its higher electrochemical activity and stability, and bulk homogeneity. Particles of Pd and Pt were electrochemically incorporated on these polymer films, and the electrocatalytic properties of such composites investigated with respect to the hydrogen oxidation (HOR) and oxygen reduction (ORR) reactions in 2.0 M sulfuric acid solutions. Previously to these kinetic studies, the composites were characterized using X-ray absorption spectroscopy from which it is seen that the catalysts are deposited as agglomerates composed of very small particles whose oxidation states are not changed by changing the electrode potential. Both catalysts present some initial activity for the HOR, but the performance is not stable due to the occurrence of a degradation process involving the polymer chain. On the other hand, it is observed that the films containing Pt show an enhanced catalytic activity for the ORR which is considerably higher than of that containing Pd. The reaction mechanism is dependent on the catalyst nature and also influenced by the contact with a polymer film coating. For Pt in direct contact with the supporting electrolyte, the reaction occurs involving 4 electrons leading to water as final product. For Pt particles covered with a polymer layer, participation of hydrogen peroxide seems to be important with only a fraction of this specie being reduced to water. In the case of Pd, the process involves formation of hydrogen peroxide at low overpotentials, which is then reduced to water at higher overpotentials.

[pt] O presente trabalho estuda a interação entre objetos condutores perfeitos tridimensionais, de formas arbitrárias e campos eletromagnéticos harmônicos no tempo incidentes sobre os mesmos. Pretende-se determinar os campos espalhados pelos objetos, caracterizados por uma malha de elementos de contorno planos e triangulares. Através de um tratamento numérico aproximado da Equação Integral do Campo Magnético, a densidade de corrente induzida na superfície do condutor perfeito é obtida. De posse deste resultado, determina-se o campo magnético espalhado (campo distante) e calcula-se a seção reta radar em várias direções. As vantagens e desvantagens da utilização do Método dos Momentos serão apontadas. Os resultados obtidos pelos mesmos serão comparados entre si e com aqueles disponíveis na literatura. / [en] This work studies the interaction between tridimensional perfect conducting objects of arbitrary shapes and incident time-harmonic electromagnetic fields. The fields, scattered by these objects, are determined using a finite number of plane and triangular boundary elements. The induced current density on the boundary is obtained using the Magnetic Field Integral Equation, applied approximately in a numerical approach. With the result mentioned above, the scattered magnetic field (far-field) is determined and the Radar Cross Section is calculated. The advantages and disadvantages of the use of a numerical method (moment method) are pointed out and the results compared. With those in literature.

Doctor of Philosophy / Curriculum and Instruction Programs / Frederick Burrack / One of the most important roles of a conductor is to prepare an ensemble to perform, not only accurately but expressively, utilizing physical gestures and facial expressions. For many music students, the development of physical gestures that elicit expressive performance are typically introduced in a beginning undergraduate conducting course. This is important in establishing a framework for understanding the technical aspects of conducting, considering that many beginning student conductors lack a basic comprehension of conducting fundamentals. However, the interpretative and expressive principles of conducting are equally important as basic technique and are often more difficult to teach to undergraduate students. There is an overwhelming amount of gestural skill that should be experienced and explored by a beginning undergraduate conductor. Despite a students’ best efforts in the classroom and in the practice room, expressive conducting skills that represent internal musical intentions remain a primary challenge with novice conducting students. The purpose of this study was to explore the experiences of a beginning undergraduate conductor as they learned to conduct and develop their considerations and skills of conducting to elicit expression. Through case study, exploring the experiences of an undergraduate music student enrolled in a beginning conducting course from a Midwestern university exposed valuable information that could become helpful when designing instruction. The findings addressed the research questions of the study and revealed additional aspects of the learning experience from the perspective of the participant. Through reflection, navigation of self, guided video elicitation, discussion of expressive conducting, and acknowledgement of prior musical expectations and intent, the participant discovered the differences between their perceived expressive gestures and the realization of an audible response from an ensemble.

Master of Music / Department of Music / Frank C. Tracz / The following document is research and analysis from the comprehensive examination question based on the Graduate Conducting Recital of Matthew S. Bradford. The recital, performed by the Clay Center Community High School Band, was given in the Martyn/Snodgrass Auditorium of Clay Center Community High School on Monday, January 29, 2007 at 7:30 PM. The repertoire included Yorkshire Ballad by James Barnes, La Virgen De La Macarena arranged by Charles Koff, Provenance by Robert W. Smith, Nessum Dorma arranged by George Hattendorf, and Brighton Beach March by William Latham. This document contains theoretical and historical analysis, and outlines the procedures of planning and performing the graduate conducting recital.

Please read the abstract in the section front of this document. / Dissertation (MSc (Chemistry))--University of Pretoria, 2006. / Chemistry / unrestricted