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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
341

Caracterização espectroscópica dos produtos da polimerização da anilina - correlação entre estrutura química e morfologia / Spectroscopic Characterization of aniline polymerization products - a correlation between chemical structure and morphology

Ferreira, Daniela Colevati 03 December 2010 (has links)
Neste trabalho foi realizado o estudo espectroscópico (UV-VIS-NIR, FTIR, Raman e RMN) dos produtos de polimerização da anilina com persulfato de amônio em condições de síntese diferentes da utilizada na síntese padrão da polianilina (pH inicial = 1). A reação foi realizada em meio de HCl (pH inicial = 3) e em meio tamponado (pH = 3). No primeiro caso foi observada a formação majoritária de oligômeros de anilina tipo cabeça-cauda, enquanto que em meio tamponado são formadas macromoléculas com segmentos do tipo 1,4 de Michael de anilina e benzoquinona monoimina com diferentes graus de hidrólise/oxidação, além de unidades tipo fenazina. Esta caracterização está de acordo com as propostas distintas de dois grupos (Surwade et al. e Stejskal et al.), que a princípio pareciam contraditórias. Ainda com relação aos produtos obtidos em meio tamponado (pH = 3), é observada a formação de microesferas com diâmetro entre 3-7 µm. A microscopia Raman juntamente com a espectroscopia Raman ressonante revelou uma correlação entre estrutura tipo fenazina e a formação das microesferas. / In this work it was performed the spectroscopic study (UV-VIS-NIR, FTIR, Raman e NMR) of the polymerization products of aniline and ammonium persulfate using different reaction conditions in relation to the standard polyaniline synthesis (initial pH = 1). The reaction was performed in HCl medium (initial pH =3) and in buffered medium (pH = 3) In the first case it was observed the major formation of aniline oligomers with head-to-tail coupling, while in buffered medium macromolecules with 1,4 Michael-type segments between aniline and benzoquinone monoimine with different hydrolysis/oxidation ratio of iminic groups are formed, in addition to phenazine-like units. This characterization is in accordance to the distinct proposals of two groups (Surwade et al. e Stejskal et al.), which at first seemed contradictory. Again, relative to the products obtained in buffered solution (pH = 3), it is observed the formation of microspheres whose diameter range is 3-7 µm. The use of Raman microscopy and resonance Raman spectroscopy revealed a correlation between phenazine-like structure and the microspheres formation.
342

Estudo da interação entre pesticidas e polímeros condutores, visando a aplicação como sensores / Studying interaction between pesticides and conducting polymers for application in sensors

Pizzolato, Priscila 28 March 2005 (has links)
Atualmente a fabricação de sensores poliméricos tem sido de grande interesse tecnológico e científico, devido à grande demanda por sensores de diversos tipos em inúmeras aplicações. Nesse contexto, a Embrapa Instrumentação Agropecuária tem buscado o desenvolvimento de novas tecnologias, instrumentação, e sensores; visando a preservação do meio ambiente, tema de grande importância mundial. Muitos produtos comercializados nos países em desenvolvimento não atendem ao padrão de qualidade FAO, e o seu mau uso leva a riscos de contaminação de solos, águas de rios, mananciais, e lençóis freáticos; prejudicando a vida aquática, e consequentemente a vida humana. Este trabalho teve um caráter exploratório, e os objetivos foram a preparação, caracterização e desenvolvimento de unidades sensoriais à base de polímeros, com o intuito de avaliar a qualidade da água através da detecção de vários pesticidas. Utilizou-se uma \"língua eletrônica\" constituída por diferentes unidades sensoriais, nas quais foram depositados filmes de polímeros condutores com composições selecionadas e otimizadas a fim de se obter respostas elétricas características para cada tipo de pesticida. Para tanto: i) sintetizou-se quimicamente os polímeros polianilina e poli(oetoxianilina) e caracterizou-se os mesmos; ii) depositou-se (através de automontagem) filmes ultrafinos dos polímeros condutores poli(o-etoxianilina), polianilina e poli(3,4-etilenodioxitiofeno) sobre microeletrodos interdigitados. Estes filmes foram investigados quanto à sensibilidade frente aos pesticidas; iii) Caracterizou-se espectroscopicamente por técnicas de ultra-violeta visível (UVVIS), e microscopicamente (MEV) os filmes e as interações entre os pesticidas e os polímeros; iv) Caracterizou-se o conjunto de unidades sensoriais através de medidas elétricas de capacitância em corrente alternada através de espectroscopia de impedância e análise estatística de Componentes Principais (PCA). Resultados bastante interessantes foram obtidos, e a \"língua eletrônica\" foi capaz de distinguir águas contaminadas com 1 µ mL-1 de pesticidas, de águas não contaminadas / Nowadays the manufacturing of polimeric sensors has been attractingv technological and cientific interests, due to the demand for different sensors in a large number of applications. In this context. Embrapa Agriculturial Instrumentation rias been looking for the development of new technologies, instrumentation and sensor, envisaging environment monitoring, theme of huge global importance. Many products that are in the market in developing countries do not follow the FAO quality standards and their use can cause risks of contamination to soil and water, damaging the acquatic life and consequently the human life. The aim of this project was the preparation. characterization and development of sensing units made by thin layers of conducting polymers, in order to evaluate the water quality mainly due to contamination of pesticides. To achieve these aims, we made use of an \"electronic tongue\" designed with different sensing units in which conductor polymeric films with specific compositions were deposited, in order to have electric responses for each type of pesticide. For that, the following studies were carried out: i) The polymers PANI and POEA were synthesized and characterized ii) these films (PANI, POEA and PEDOT/PSS) were deposited by self-assembly on gold interdigited microelectrodes. The sensibility of these films to different pesticides was evaluated; iii) the interactions between pesticides and polymers were monitored by visible ultraviolet spectroscopic (UV-VIS) and microscopy techiques (SEM); iv) the sensing units were characterized by impedance measurements and by Principal Component Analysis (PCA). Using eight sensing units with PANI, POEA and PEDOT/PSS films it was demonstrated the possibility to detect some pesticides in concentration of 1 µ mL-1 and to distinguish contaminated samples from non contaminated
343

Study of modification on poly(3,4-ethylenedioxythiophene): poly(styrenesulphonate) thin films with X-ray photoelectron spectroscopy and conducting atomic force microscopy. / 利用X光电子谱和导电原子力显微镜对聚3, 4-乙烯二氧噻酚 / Study of modification on poly(3,4-ethylenedioxythiophene): poly(styrenesulphonate) thin films with X-ray photoelectron spectroscopy and conducting atomic force microscopy. / Li yong X guang dian zi pu he dao dian yuan zi li xian wei jing dui ju 3, 4-yi xi er yang sai fen

January 2005 (has links)
Wang Yuhao = 利用X光电子谱和导电原子力显微镜对聚3, 4-乙烯二氧噻酚 : 聚苯磺酸改性的研究 / 王宇昊. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / Wang Yuhao = Li yong X guang dian zi pu he dao dian yuan zi li xian wei jing dui ju 3, 4-yi xi er yang sai fen : ju ben huang suan gai xing de yan jiu / Wang Yuhao. / Abstract --- p.ii / 論文摘要 --- p.iii / Acknowledgements --- p.iv / Table of Contents --- p.v / List of Figures --- p.ix / List of Tables --- p.xiii / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Review of conducting conjugated polymers --- p.1 / Chapter 1.1.1 --- Development of conjugated polymer --- p.1 / Chapter 1.1.2 --- Basic concepts in independent-electron theories of conducting conjugated polymers --- p.2 / Chapter 1.1.2.1 --- "Huckel model and its difficulty, the importance of election-phonon" --- p.2 / Chapter 1.1.2.2 --- The SSH model and dimerization --- p.3 / Chapter 1.1.2.3 --- "Charge carriers in conducting conjugated polymers: soliton, polaron and bipolaron" --- p.5 / Chapter 1.1.3 --- "Poly(3,4-ethylenedioxythiophene) or PEDT" --- p.5 / Chapter 1.1.4 --- Derivatives of PEDT --- p.6 / Chapter 1.1.5 --- Application of PEDT and its derivatives --- p.7 / Chapter 1.2 --- Polymeric light emitting diodes (PLED) --- p.7 / Chapter 1.2.1 --- Invention Polymeric light emitting diodes (PLED) --- p.7 / Chapter 1.2.2 --- Electric structure of PLEDs --- p.7 / Chapter 1.2.3 --- Transition from excitons to photons --- p.8 / Chapter 1.2.4 --- Controlling electron and hole injection --- p.8 / Chapter 1.2.5 --- Application of PEDT-PSS as hole transporting layer in PLED --- p.9 / Chapter 1.2.6 --- "Phase separating in PEDT-PSS blend, removing the PSS rich layer" --- p.9 / Chapter 1.3 --- Motivations of the thesis work --- p.10 / References --- p.10 / Chapter CHAPTER 2 --- INSTRUMENTATION --- p.27 / Chapter 2.1 --- X-ray Photoelectron Spectroscopy --- p.27 / Chapter 2.1.1 --- History of XPS techniques --- p.27 / Chapter 2.1.2 --- Physical Basis --- p.28 / Chapter 2.1.3 --- Chemical Shift of Binding Energy in XPS --- p.29 / Chapter 2.1.4 --- Binding Energy Referencing in XPS --- p.29 / Chapter 2.1.5 --- Sampling Depth of XPS --- p.30 / Chapter 2.1.6 --- Instrumental Setup of XPS --- p.30 / Chapter 2.2 --- Scanning Probe Microscopy --- p.31 / Chapter 2.2.1 --- Introduction --- p.31 / Chapter 2.2.2 --- Atomic Force Microscopy and Conductive Atomic Force Microscopy --- p.31 / Chapter 2.2.3 --- Instrumental Setup for Conductive AFM --- p.32 / Chapter 2.3 --- The Low Energy Ion Beam (LEIB) system at CUHK --- p.32 / Chapter 2.3.1 --- Introduction --- p.32 / Chapter 2.3.2 --- Principle --- p.33 / Chapter 2.3.3 --- Instrumentation Setup --- p.33 / References --- p.33 / Chapter CHAPTER 3 --- Effects of Ar+ bombardment at 500 and 100eV --- p.42 / Chapter 3.1 --- Introduction --- p.42 / Chapter 3.2 --- Sample Preparation --- p.42 / Chapter 3.3 --- Ar+ sputtering and XPS measurement of the sputtered sample. --- p.43 / Chapter 3.4 --- Results and Discussion --- p.44 / References --- p.49 / Chapter CHAPTER 4 --- Effects of annealing on PEDT-PSS thin films studied by XPS and AFM --- p.60 / Chapter 4.1 --- Introduction --- p.60 / Chapter 4.2 --- Sample Preparation --- p.60 / Chapter 4.3 --- XPS measurements and results --- p.61 / Chapter 4.3.1 --- XPS of C 1s core level of PEDT-PSS --- p.61 / Chapter 4.3.2 --- XPS of O 1s core level of PEDT-PSS --- p.62 / Chapter 4.3.3 --- XPS of S 2p core level of PEDT-PSS --- p.62 / Chapter 4.3.4 --- XPS of Valence Band of PEDT-PSS --- p.64 / Chapter 4.4 --- C-AFM measurements and results --- p.65 / Chapter 4.4.1 --- C-AFM measurements on PEDT-PSS --- p.65 / Chapter 4.5 --- Measurements and results about film insolubility and conductivity --- p.65 / Chapter 4.5.1 --- Insolubility measurements --- p.66 / Chapter 4.5.2 --- Conductivity measurements --- p.66 / Chapter 4.5.3 --- Results from the film insolubility and conductivity measurements --- p.66 / Chapter 4.6 --- Conclusion --- p.67 / References --- p.68 / Chapter CHAPTER 5 --- Effects of low energy proton bombardment of PEDT-PSS films studied by XPS and AFM --- p.90 / Chapter 5.1 --- Introduction --- p.90 / Chapter 5.2 --- XPS and c-AFM studies of PEDT-PSS films bombarded by H+ --- p.90 / Chapter 5.2.1 --- Sample preparation --- p.90 / Chapter 5.2.2 --- Results and discussion --- p.90 / Chapter 5.3 --- Conductivity measurements --- p.92 / Chapter 5.3.1 --- Sample preparation for conductivity measurements --- p.92 / Chapter 5.3.2 --- Results and discussion --- p.93 / Chapter 5.4 --- Conclusion --- p.93 / References --- p.93 / Chapter CHAPTER 6 --- Concluding Remarks and Future Works --- p.106 / Chapter 6.1 --- Concluding Remarks --- p.106 / Chapter 6.2 --- Future Work --- p.106 / Chapter APPENDIX --- The SSH model in describing polyacetylene --- p.108 / Chapter Part 1 --- Assumptions of the SSH model --- p.108 / Chapter Part 2 --- Bloch model and SSH model. --- p.113 / Reference --- p.117
344

Polymères hydrocarbonés superhydrophobes élaborés par polymérisation électrochimique : une alternative à la chimie du fluor ? / Hydrocarbon superhydrophobic polymers from electrochemical polymerization : an alternative to fluorine ?

Wolfs, Mélanie 13 December 2013 (has links)
Une surface est dite superhydrophobe si l’angle de contact d’une goutte d’eau avec cette surface est supérieur à 150°. Les domaines d’application de telles surfaces anti-adhérentes sont variées : du bâtiment avec l’élaboration de vitres anti-salissures au biomédical pour empêcher ou limiter l’adhésion bactérienne en passant par l’aéronautique. La superhydrophobie provient de la combinaison de deux paramètres : la structuration de la surface et la faible énergie de surface du matériau. Dans la plupart des références de la littérature, l’élaboration de telles surfaces s’effectue en plusieurs étapes. La polymérisation électrochimique de monomères conducteurs est une technique simple, rapide et reproductible pour obtenir des surfaces superhydrophobes. En effet, en une seule étape, le film de polymère se dépose et se structure. Cette méthode permet de contrôler les propriétés de mouillage en jouant sur les paramètres électrochimiques (charge de dépôt, substrat, sel électrolyte) ou sur la structure chimique du monomère. Ce travail porte sur l’élaboration et la caractérisation de films de polymères conducteurs obtenus par électrodéposition de dérivés du 3,4-éthylènedioxythiophene (EDOT), du 3,4-ethylènethiathiophene (EOTT) et du 3,4-propylenedioxythiophene (ProDOT) portant une chaîne hydrocarbonée de longueur variable. Des surfaces aux propriétés de mouillage polyvalentes (hydrophiles à superhydrophobes) ont été obtenues. De plus, l’influence de la part chimie et de la part physique sur l’angle de contact à l’eau a été déterminée pour les EDOT hydrocarbonés. Ce travail contribue à trouver une alternative aux composés fluorés. dans la domaine de la superhydrophobie. / Controlling wettability of a solid surface is important in many practical applications. This property, resulting from the combination a low surface energy material with a surface structuration, is commonly expressed by the contact angle of a water droplet on the surface. Surfaces with a water contact angle (θwater) larger than 150° are usually called superhydrophobic surfaces. Such surfaces are very interesting because of their expected self-cleaning or anti-contamination properties, which could be applied in various applications such as in biomedical devices, paint or in aeronautics for example. Among all the techniques to prepare superhydrophobic surfaces, electrochemical polymerization is a fast and versatile technique. In current literature on this field, the general approach is the use of highly fluorinated tails to reach the water-repellency. However, as observed in nature, fluorine is not necessary and can present environmental impacts. In this work, we focused on the synthesis of original monomers with hydrocarbon chain as hydrophobic part in order to find alternative to fluorine chemistry to prepare electropolymerized superhydrophobic surfaces. We succeeded to reach high water repellency (θwater > 150°) with hydrocarbon conducting polymers and we determined the influence of chemical and physical parts onto the water contact angle. We also found similar dewetting properties than the fluorinated series meaning the hydrocarbon conducting polymers could be a real alternative to fluorine chemistry.
345

Blendas condutoras a base de água para proteção à corrosão / Water-based conducting blends for corrosion protection

Melo, Luciana de Oliveira 16 December 2005 (has links)
A obtenção de blendas condutoras a base de água, ainda é pouco explorada e apresenta uma interessante alternativa ao uso de compostos poluentes como os cromatos na proteção à corrosão metálica. Os polímeros condutores apresentam propriedades anti-corrosivas e podem ser processados em meio aquoso, eliminando o uso de solventes orgânicos altamente tóxicos e agressivos para o meio ambiente. O presente trabalho consiste no estudo da proteção da corrosão metálica por revestimento de filmes de blendas contendo Poli(anilina) (PANI). As blendas foram obtidas à partir da mistura de uma suspensão aquosa de PANI com uma dispersão aquosa de Poli(metil metacrilato). O uso de técnicas como potencial zeta, espalhamento de luz dinâmico, análise térmica e microscopia eletrônica de varredura permitiram a caracterização da mistura homogênea obtida. Medidas através do método da sonda de quatro pontas mostraram que as blendas apresentam condutividade mesmo com baixas quantidades de PANI e a técnica de espectroscopia Raman mostrou a presença da forma condutora deste polímero nos filmes das blendas. Técnicas como microscopia óptica, potencial a circuito aberto, voltametria linear e espectroscopia de impedância eletroquímica permitiram avaliar a proteção à corrosão de eletrodos metálicos de ferro, cobre e níquel recobertos com filmes das blendas de PANI em diferentes meios corrosivos. As blendas mostraram eficiência contra a corrosão e apresentam-se como um novo material não poluente para a proteção à corrosão metálica. / The development of water-based conducting blends has not yet been very much explored and it presents itself as an interesting alternative to the use of polluting compounds such as chromates in the protection of metals from corrosion. The conducting polymers present anti-corrosion properties and can be processed in aqueous medium, eliminating the use of organic solvents, which are highly toxic and threatening to the environment. This thesis is based on the study of protection from metallic corrosion using poly(aniline) (PANI) coating blends. The blends have been obtained by mixing a PANI aqueous suspension with a poly(methyl metacrylate) aqueous dispersion. Techniques such as zeta potential, dynamic light scattering, thermal analysis and scanning electronic microscopy allowed the characterization of the homogeneous mixture obtained. Measurements carried out by the four-point probe method showed that the blends present conductivity even despite low PANI quantities. In addition, the Raman spectroscopy technique showed the presence of the conducting form of this polymer on the blend films. Techniques such as optical microscopy, open-circuit potential, linear voltammetry and impedance spectroscopy allowed the evaluation of the corrosion protection of the iron, copper, and nickel metallic electrodes coated with PANI blend films in different corrosives mediums. The blends showed efficiency against corrosion and they are therefore a new environmentally friendly material for metallic corrosion protection.
346

Synthèse et caractérisations thermoélectriques de polyaniline dopée / Synthesis and characterization of thermoelectric properties of doped polyaniline

Brault, Damien 13 December 2018 (has links)
Dans le contexte actuel de recherche d’efficacité énergétique, c’est-à-dire de maîtrise de l’énergie incluant la valorisation de l’énergie perdue, ce projet de thèse propose de synthétiser et caractériser les propriétés thermoélectriques de la polyaniline dopée. Nous avons ainsi synthétisé plusieurs échantillons de polyaniline et étudié l’influence des conditions de synthèse, du taux de dopage, du type de dopant, du taux de cristallinité ou de la mise en forme du matériau fini sur leurs propriétés thermoélectriques. Tout d’abord, nous avons mesuré les dépendances en température des conductivités électriques et thermiques ainsi que du coefficient Seebeck de la polyaniline dopée à l’acide chlorhydrique (Pani/HCl). Nous avons montré que lors de la synthèse, une température de polymérisation basse (223K) permet d’obtenir de meilleures conductivités électriques et donc des propriétés thermoélectriques améliorées. D’autre part, la valeur de la pression utilisée pour compresser le matériau et le mettre en forme doit être assez élevée (1.109GPa) pour optimiser les performances thermoélectriques. Afin de mieux comprendre les propriétés de transport de la polyaniline dopée au chlorure, nous nous sommes ensuite intéressés à ses propriétés magnétiques et calorifiques. Les mesures de la susceptibilité magnétique et de la capacité calorifique du polymère dopé en fonction de la température ont ainsi permis de déterminer la nature de ses états électroniques et de déduire le type de transport au sein du polymère. Enfin, nous avons synthétisé et étudié la polyaniline dopée au camphresulfonate en faisant varier le taux de dopage entre 30% et 90%. Les mesures de conductivités électriques, thermiques et du coefficient Seebeck en fonction de la température montrent qu’un optimum peut être trouvé pour un taux de dopage de 50%. / In the actual frame of energy efficiency research, namely, the energy management including wasted energy, this PhD project deals with the synthesis and characterization of thermoelectric properties of doped polyaniline. Consequently, polyanilines have been synthesized and the effect of the synthesis conditions, the doping level, the type of dopant, the crystallinity or the sample preparation of the final material on the thermoelectric properties have been studied. Firstly, we measured the thermal dependencies of electrical and thermal conductivities as well as Seebeck coefficient hydrochloric acid doped polyaniline (Pani/HCl). We showed that a low polymerization temperature (223K) lead to better electric conductivity and so improved thermoelectric properties. On the other side, the pressure used to compress powders should as high as 1.109GPa to optimize the thermoelectric performance. Then, in order to have a better understanding of the transport properties of chloride doped polyaniline, we investigate the magnetic and thermal properties. Measurements of the specific heat and the magnetic susceptibility of chloride doped polyaniline as a function of the temperature allowed to determine the electronic states and the mechanism of transport in the polymer chains. Finally, we synthesized and studied camphorsulfonate doped polyaniline by varying the doping level between 30% and 90%. The electrical, thermal conductivities and Seebeck coefficient as a function of the temperature show clearly on optimum of doping level at 50% with camphorsulfonate doping agent.
347

PAUL DOOLEY’S <em>MASKS AND MACHINES</em>: A FORMAL ANALYSIS AND INSTRUCTIONAL GUIDE

Callihan, Kevin M. 01 January 2018 (has links)
Paul Dooley’s composition, Masks and Machines (2015), is a significant new work for wind ensemble and was the winner of the National Band Association’s William D. Revelli Memorial Band Composition Contest award and the American Bandmasters Association’s Sousa/ABA/Ostwald Composition Contest. Masks and Machines has received positive critical acclaim and numerous performances, including a performance at the 2015 Midwest Band and Orchestra Clinic in Chicago, Illinois by the North Texas Wind Ensemble under the direction of Eugene Corporon and a performance at the 2016 American Bandmasters Association Conference in Lexington, Kentucky by the United States Marine Corps Band under the direction of Jason K. Fettig. The purposes of this dissertation are 1) to place Masks and Machines in its historical perspective within the history of wind band compositions; 2) to provide an overview of the artistic styles that influenced the composer, such as Stravinsky’s Neoclassical works, Bauhaus Art, and Fortspinnung; 3) to elaborate on the musical traits and characteristics of Masks and Machines via formal analysis; and 4) to offer a guide to rehearsal and performance of the work. The Introduction discusses Masks and Machines in its historical context as a highly acclaimed wind ensemble composition within the canon of twentieth century wind band works. Chapter 1 includes a detailed biography of Paul Dooley. Chapter 2 discusses the visual art and musical influences on Paul Dooley and how these influences come to life in his wind band compositions. Chapter 3 is an analysis of Masks and Machines with thematic excerpts and discussions on form, instrumentation, orchestration, and compositional techniques. Chapter 4 provides a rehearsal and performance guide aimed to facilitate a successful performance of Masks and Machines. Chapter 5 includes a transcription of two interviews with the composer and focuses primarily on compositional influences, processes, and techniques regarding Masks and Machines and other wind band compositions by Dooley, such as Point Blank (2012), Meditation at Lagunitas (2014), and Mavericks (2016).
348

AN ANALYSIS AND CONDUCTOR’S GUIDE TO ZDENĚK LUKÁŠ’ <em>REQUIEM PER CORO MISTO, OP. 252</em>

Miller, Samuel James 01 January 2018 (has links)
Zdeněk Lukáš (1928-2007) was one of the most prolific Czech composers of the 20th century having composed over 300 pieces. His works include a wide array of genres including symphonies, operas, chamber music, and a large amount of choral and vocal music. He was influenced by Czech folklore and music and was self-taught until he was nearly 40 years old. Lukáš began his career as a teacher but later began working for the Czechoslovak Radio Studio in Plzeň where he founded the mixed choir, Česká Píseň (Czech Song), which became quite famous and still enjoys great fame. Requiem per coro misto, op. 252 is considered by many to be Lukáš’s most famous choral work. It was written in 1992 for a cappella SSATB chorus. The piece is divided into seven movements; “Requiem aeternam,” “Dies irae,” “Lacrymosa,” “Offertorium,” “Hostias,” “Sanctus,” and “Agnus Dei.” This document presents an analysis and conductor’s guide of Requiem. The analysis includes an examination of Latin pronunciation employing Germanic Latin when possible and an IPA pronunciation guide and translation of the text. Also included in the analysis is discussion on form, tonality, and development of melody, harmony, and rhythm all of which reveal that Lukáš wrote this piece in a very traditional style. The conductor’s guide points out many of the issues that a choir may face in preparing Requiem. Some of the issues include intonation, range, and dynamics. One specific issue is that although the piece is tonal, there is considerable use of modes and scales that many singers would consider exotic. One such scale is the Hungarian Gypsy which is essentially a harmonic minor scale, but includes a raised fourth degree. Many of the intonation issues that could arise stem from the frequent parallel motion. Lukáš believed that a cappella singing is one of the purest forms of music and that singers should be allowed to sing without regard to any instrumental influence whether it be from the composer or some other source. Requiem exhibits this belief through its challenges and its beauty. The work or its individual movements can be challenging yet accessible to singers of all levels.
349

EFFECT OF HYDROGEN EXPOSURE ON THE ELECTRONIC AND OPTICAL PROPERTIES OF INSULATING TITANATES

Connell, John G. 01 January 2019 (has links)
Hydrogen exposure of insulating d0-titanates, such as SrTiO3 (STO), has displayed the formation of intriguing conducting states. These conducting states form through the use of forming gas (N2/H2) annealing or hydrogen plasma exposure, where hydrogen gas is exposed to high energy microwaves. The exposure of STO to hydrogen causes metallic conductivity due to the introduction of hydrogen cations on some of the oxygen sites. However, the optical properties of this hydrogen-exposed STO have not been well-studied. Further, Ba0.5Sr0.5TiO3 (BST), an insulating dielectric, also shows changes in its conductivity upon hydrogen exposure. Unlike STO where the conductivity of the hydrogen-exposed material has been characterized, the optical, electronic, and transport properties of hydrogen exposed BST have not been studied. Thus, by studying hydrogen-exposed BST and STO, our understanding of the effects of hydrogen on insulators can be enhanced. In the first study, the effects of the exposure of insulating dielectric BST thin films to a hydrogen plasma is presented. These BST thin films are deposited on GdScO3 (GSO) substrates via Pulsed Laser Deposition (PLD). After deposition, the thin films are exposed to a hydrogen plasma. Just five minutes of hydrogen plasma exposure is enough to induce conductivity in the BST thin film. This conducting state is dominated by the interplay of disorder and strong electron correlations introduced during hydrogen exposure. Further, the optical properties indicate the formation of a transparent conductor, as the introduction of disorder and strong correlations has not changed the optical properties of the BST thin film in the visible spectrum. BST demonstrates an example of a new type of transparent conductor that utilizes large effective mass carriers to generate conductivity. In the second study, the effects of hydrogen doping on the surface of STO is explored. The conducting heterointerface that forms between PLD-deposited thin films of LaAlO3 (LAO) on STO is used as the standard to explore this hydrogen surface doping. The optical, electronic, and transport properties of water-leached and buffered hydrofluoric acid (BHF) etched heterointerfaces are characterized and compared. The recently developed water-leaching method is compared with the well-known BHF etching method, which has been shown to unintentionally dope the STO surface with fluorine and hydrogen. Both methods generate single-terminated atomically flat STO substrate surfaces that are ideal for heterointerface formation. After deposition, the optical, electronic, and transport properties of both the water-leached and BHF-etched heterointerfaces show no meaningful difference, demonstrating that water-leaching may also unintentionally dope the STO substrate surface with hydrogen. However, these results confirm that water-leaching generates a high-quality conducting heterointerface without the safety concerns of BHF.
350

PARTITA FOR 8 VOICES & WIND ENSEMBLE: A TRANSCRIPTION PROCESS

Bove, Kaitlin May 01 January 2019 (has links)
Partita for 8 Voices (2012) is a groundbreaking a cappella work that earned its composer, Caroline Shaw, the record of youngest recipient of the Pulitzer Prize for Music in 2013. While the work continues to receive performances from its premiere ensemble, Roomful of Teeth, no transcription of the piece to any other ensemble type existed at the beginning of this DMA project. The author sought to transcribe a piece by a living female composer with no work for band into the wind band medium. The resulting transcription, Partita for 8 Voices & Wind Ensemble, adds a new work to the repertoire of band literature that includes new, esoteric, and proprietary extended technique for wind and percussion instruments. The purposes of this DMA project are 1) to provide a brief analysis of Partita for 8 Voices, 2) to provide details of the trials, errors, and successes during the transcription process of Partita for 8 Voices & Wind Ensemble as well as recommendations for future conductors of the work, and 3) to provide anecdotal evidence of the important relationship conductors build with composer intent by embarking on a transcription process. The first chapter includes a biography of Caroline Shaw, the vocal ensemble Roomful of Teeth, and a timeline of Shaw’s compositional process regarding Partita for 8 Voices. The second chapter is a brief theoretical, timbral, and technical analysis of Partita for 8 Voices. Chapters three through seven discuss the transcriptional process and conductor’s insights for each of the four movements of Partita for 8 Voices & Wind Ensemble and general considerations. Chapter eight discusses anecdotal evidence of what conductors learn from the transcription process. An appendix of information including interviews, a graphical analysis of technical and timbral events in Partita for 8 Voices, and the full score for Partita for 8 Voices & Wind Ensemble is also provided.

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