Neste trabalho descreve-se a construção de dois equipamentos controladores da temperatura da amostra, que operam entre 77K e 300K e entre 300K e 700K. Apresenta-se os resultados de medidas de T1 e T2, no intervalo de 77K e 700K, realizadas com o campo estático Ho paralelo à direção [111] e uma radiofreqüência de 24MHz. Discutem-se os comportamentos de T1 e T2 neste intervalo de temperaturas e os possíveis mecanismos de relaxação, spin nu clear-rede e spin eletrônico de impureza-rede, atuantes. / In this work we describe the construction of two sample temperature controlled equipments that operate between 77K and 300K and between 300K and 700K. We show the results of T1 and T2 measurements over the temperature range of 77K to 700K with the static field Ho parallel to [111] direction and 24MHz. We discuss the T1 and T2 behavior in this range temperature and the possible relaxation mechanisms of spin nuclear and spin electronic of impurity to lattice that are present.

Ionômeros são polímeros carregados que possuem uma variedade de propriedades elétricas e que recentemente vêm sendo aplicados como camadas de transporte em dispositivos poliméricos. Em particular, camadas ultrafinas de ionômeros são depositadas entre o eletrodo e o polímero eletrônico em OLEDs para aumentar a eficiência da injeção de cargas. Entretanto o sucesso desta aplicação envolve fenômenos de armazenamento e mecanismos de transportes de cargas dentro do ionômero que ainda não são claramente entendidos. Neste trabalho foi utilizada a técnica da corrente despolarização termoestimulada (TSDC) com o propósito de esclarecer alguns efeitos relacionados a esse fenômeno. Nós utilizamos o poliestireno sulfonado (X-SPS) com lítio (X = Li) ou potássio (X = K) como contraíon. Foram obtidos filmes ultrafinos com 50 nm de espessura por spincoating obtendo a estrutura metal-polímero-metal para estudo, tendo como metal o alumínio. A técnica de TSDC consiste no aquecimento de uma amostra previamente polarizada a um taxa de aquecimento constante e a corrente de despolarização é medida em função da temperatura da amostra. Os resultados experimentais mostraram que cada termograma apresenta dois picos, sendo que um dos deles mostrou-se fortemente dependente das condições de polarização, ou seja, dependendo da temperatura de polarização e da intensidade do campo de polarização. Os picos foram estudados através da cinética de primeira ordem para a dinâmica de armazenamento e transporte, e dos ajustes teórico-experimental foram obtidos importantes parâmetros, tal como, a energia de ativação e concentração de espécies ativas. / Ionomers are charged polymers that exhibit a great variety of electrical properties and more recently they have been applied as transport layers at polymer devices. In particular, thin films of ionomer have been deposited between the electrodes and the electronic polymers in OLEDs to improve the efficiency of the charge injection. Despite the success of such application, the involved phenomena related to the charge storage and transport mechanisms inside the ionomer thin layer are not clear yet. In this work we used thermal stimulated depolarization current technique (TSDC) with the purpose to elucidate such phenomena. We used for this a sulfonated polystyrene (X-SPS) having lithium (X = Li) or potassium (X = K) as cation counter-ions, and we make structure of metal-polymer-metal in which the polymer is a thin film of SPS, at about 50 nm thick and deposited by spincoating, having aluminum as metal. TSDC technique consists of warm up a previously polarized sample at a constant rate of heating and measure the depolarization current in function of the temperature. The experimental results showed that each thermogram presents two peaks, one of them very dependent on the polarization conditions, i. e., it depends on the polarization temperature and the intensity of the polarization bias. The peaks were studied by considering first order trapping-detrapping (or dipole relaxation) kinetics, from which important parameters, as the activation energy, were obtained.

Orientadores: Edvaldo Sabadini, Fred Yukio Fujiwara / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Quimica / Made available in DSpace on 2018-08-05T11:17:03Z (GMT). No. of bitstreams: 1 Egidio_FernandadoCarmo_M.pdf: 997650 bytes, checksum: 3662c5dade756ee697c267ad8996aa15 (MD5) Previous issue date: 2005 / Resumo: Ciclodextrinas (CD) são oligossacarídeos cíclicos produzidos pela ação enzimática microbiológica sobre o amido. As três ciclodextrinas naturais disponíveis comercialmente são a-CD, b-CD e g-CD, constituídas por 6, 7 e 8 unidades glicosídicas, respectivamente. Possuem estrutura rígida representada como um cone truncado oco com cavidade hidrofóbica, formada pelos grupos CH2 e éter, e exterior hidrofílico, contendo os grupos hidroxila. Esses oligossacarídeos interagem com uma ampla variedade de moléculas, formando complexos de inclusão, e a interação com polímeros pode levar à formação de estruturas supramoleculares. As ciclodextrinas apresentam uma solubilidade anômala em água, com uma tendência irregular, sendo a b-CD aproximadamente dez vezes menos solúvel que as outras duas ciclodextrinas da série homóloga. O mesmo comportamento é observado quando D2O é o solvente, mas, neste caso, a solubilidade é ainda menor para as três ciclodextrinas. Pode-se explicar esse comportamento em termos do efeito causado pelas ciclodextrinas na estrutura do solvente e pela solvatação destas moléculas. A solvatação pode ser estudada por Ressonância Magnética Nuclear, RMN, através de medidas do tempo de relaxação transversal T2 do solvente. Os valores de T2 são diferentes para moléculas de solvente livres e ligadas à superfície do soluto, devido à processos dinâmicos, como a rotação molecular. O T2 é muito sensível à interação do solvente com o soluto, de forma que a presença de um soluto diminui o T2 das moléculas do solvente diretamente ligadas ao soluto. Este trabalho fez o estudo da solubilidade e solvatação das ciclodextrinas considerando também o equilíbrio entre o estado sólido e a solução saturada. Os cristais de ciclodextrinas foram estudados por Difração de Raios-X e Análise Termogravimétrica. A estrutura molecular dos oligômeros afetam sua flexibilidade, solvatação e acomodação no meio líquido, resultando na anomalia na solubilidade em H2O e D2O. / Abstract: Cyclodextrins (CD) are cyclic oligomers produced by the action of certain microbial enzymes on starch. The commercially available members of this series are a-CD, b-CD and g-CD, having 6, 7 and 8 glucose units, respectively. They have a rigid structure pictorially represented as a truncated cone with a hydrophobic cavity, which are formed by CH2 and ether groups, and a hydrophilic exterior with hydroxyl groups at the rims. The cyclodextrins are known to interact with different types of molecules, including polymers, forming supramolecular inclusion compounds. The cyclodextrins molecules present an anomalous solubility in water and an irregular trend is observed in the series. b-CD is almost ten times less soluble than the others two cyclodextrins. The same behavior is observed when D2O is the solvent, however, in this solvent the solubility of three cyclodextrins is much lower. This behavior is explained in terms of the effect caused by cyclodextrins on the water lattice structure and by the solvation of these molecules. The cyclodextrins solvation was studied using transversal relaxation time (T2) of water in Nuclear Magnetic Resonance experiments. The T2 of free water and the water bounded on the surface of a solute are different due to the differences in their molecular dynamics (mainly the rotation). Hence, T2 of the solvent is very sensitive to interaction between solute and solvent and becomes lower as the solute concentration increases. In this work, not only the solubility and solvation of cyclodextrins were studied, but also the solid phase in equilibrium with the concentrated solution. The solid phase was studied by X-Ray Diffraction and Thermogravimetric Analysis. The molecular structures of cyclodextrins influence their flexibility and solvation, which leads to the anomalous solubility of the three cyclic oligomers in H2O and D2O. / Mestrado / Físico-Química / Mestre em Química

Orientador: Teresa Dib Zambon Atvars / Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Química / Made available in DSpace on 2018-08-25T12:38:23Z (GMT). No. of bitstreams: 1 Domingues_RaquelAparecida_D.pdf: 6835134 bytes, checksum: cb024bd183c16c1ab7db85bee2dd72dc (MD5) Previous issue date: 2013 / Resumo: Neste trabalho foram estudadas as propriedades fotofísicas de dois derivados de polifluoreno, F8BT e PFO-MEHPPV, visando determinar a influência de substratos sobre as mesmas. Os materiais na forma de filme foram depositados por spin coating em substrato de vidro e de vidro recoberto com ITO, sendo que as espessuras variaram de 50 nm a 600 nm, além de um filme preparado por casting com espessura de 50 ?m. As propriedades fotofísicas estudadas foram: os espectros de emissão, a largura à meia altura (FWHM) dos espectros, a posição do máximo de emissão da banda 0-0 em função da temperatura e a progressão vibrônica dos espectros de emissão. Para ambos os polímeros e dentro da faixa de espessura estudada foi verificado que a diminuição na espessura do filme causa também uma diminuição na temperatura de transição vítrea, sendo que abaixo de 450 nm o filme fino apresenta desvios de comportamento de bulk. O tipo de substrato não influenciou nas temperaturas de relaxação. Foi possível dividir os filmes de F8BT em dois grupos: espessuras de 52-185 nm que induzem maiores alargamentos inomogêneos e, portanto possuem ambientes cibotáticos heterogêneos para os fluoróforos inseridos na matriz; e espessuras maiores que 450 nm que possuem Tg maiores e menores alargamentos inomogêneos com ambientes mais homogêneos ao longo da matriz. Para o PFO-MEHPPV temos a relação que quanto maior a espessura, maior a Tg e maior o alargamento inomogêneo. Filmes mais espessos de PFO-MEHPPV encontram-se localmente menos organizados, e diferentemente do observado para os filmes de F8BT, o substrato estaria favorecendo algum grau de organização nos filmes em relação ao bulk. Medidas de tempo de vida de fluorescência foram utilizadas para estudar as interações nas interfaces do polímero orgânico com ITO e alumínio. A camada de alumínio foi considerada supressora para as diversas espessuras estudadas, e esta supressão foi atribuída aos processos de interferência, transferência de energia para o eletrodo metálico e difusão excitônica. O processo de interferência foi determinado através de modelo existente na literatura e sua menor contribuição ocorre em espessuras menores, nas quais os processos de transferência de energia são importantes. Com isso, foi possível concluir, a partir de todos os dados fotofísicos obtidos, que para espessuras acima de 450 nm os filmes deixam de ter comportamento de filme fino / Abstract: In this work, the influence of substrate on the photophysical properties of two polyfluorene derivatives, F8BT and PFO-MEHPPV was studied. The films were prepared by spin-coating solutions of the polymers, using glass and ITO coated glass as the substrates. The thickness was varied from 50 nm to 600 nm. A cast film with a thickness of 50 ìm was also prepared using both polymers. The photophysical properties of the two polyfluorene derivatives, F8BT and PFO-MEHPPV were studied using their emission spectra, the full width at half maximum (FWHM) of the spectra, the temperature dependence of the peak position of the 0-0 emission band and the vibronic progression of the emission spectra. For both polymers, F8BT and PFO-MEHPPV, as the film thickness decreased the glass transition temperature decreased. Below a film thickness of 450 nm, a deviation from bulk behavior was observed. It is also importante note that the substrate type did not affect the relaxation temperature. It was possible to classify the F8BT films into two groups. Those with thicknesses between 52 nm to 185 nm have shown greater inhomogeneous broadening and very heterogeneous cybotatic environments for the fluorophores, while those with film thicknesses greater than 450 nm have shown higher Tg values which induce lower inhomogeneous broadening. PFO-MEHPPV also has shown a similar trend. As the thickness of the film increased, a higher Tg was observed. However, thicker films of PFO-MEHPPV were observed to be less locally organized, in contrast to the F8BT films of the same thickness. This might be due to the substrate, which would favor some degree of organization in the films in comparison to the bulk material. Time-resolved PL measurements have also been used to characterize the interface interactions between the polymer film and ITO (polymer/ITO) or aluminum (polymer/aluminum). The aluminum layer acted as a quencher through an interference effect, energy transfer to the metal and excitonic diffusion. The interference effect was determined by using a model described in the literature however, it has a minimal effect in thinner films. The evidence gained from the photophysical measurements indicates that these films with thicknesses above 450 nm do not show thin film behavior / Doutorado / Físico-Química / Doutora em Ciências

Polypeptides are polymerized chains of amino acids linked covalently through peptide bonds. Polyelectrolyte polypeptides are polypeptides with electrolyte repeating groups. Several amino acids contain ionizable side chains which result in charge distributions when dissolved in aqueous solutions. This dissertation is motivated by a desire to gain knowledge of polyelectrolyte polypeptides as recent advances in chemical synthesis of polypeptides have made possible the fabrication of designed polypeptides that do not naturally occur in nature. Potential applications of newly designed polypeptides span the range from medical to clothing and energy even to robotics. In this dissertation we compare the characteristic behavior of two polypeptide polyanions: Poly-(L-Glutamic Acid) [PLE] and Poly-(L-Glutamic Acid4, Tyrosine1) [PLEY(4:1)]. Comparative characteristic behaviors of each is conducted through relaxation phenomena in the context of mechanical elasticity measurements of hydrogels and dielectric relaxation of aqueous solutions in a radio frequency range of 1 MHz to 1000 MHz. Hydrogels are fabricated by crosslinking each polyanion with Poly-(L-Lysine) [PLK], a polycation, via the crosslinker 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrochloride (EDC). Elasticity and viscoelasticity measurements are conducted in a fixture designed by our lab. Dielectric relaxation behavior is studied on aqueous solution of both PLEY and PLE using a capacitive fixture, also designed in our lab. RF signals provided by an impedance analyzer are converted to permittivity and dielectric loss measurements. Peaks in dielectric loss provide evidence of relaxation mechanisms. A comparison of experimental results to theoretical expectations reveal both expected and some surprising behavior. Relaxation times for crosslinked hydro-gels scale according to theoretical expectations according to so-called reptation dynamics. However, relaxation times of aqueous solutions did not scale as entangled polyelectrolytes. First, both PLEY and PLE scaled as neutral polymers rather than polyelectrolytes. This was expected because of the high concentrations studied. However, due to the high concentrations, it was expected that polypeptides were entangled in solutions. Data compared to theory did not support this expectation. We, additionally, conducted a self-crosslinking experiment of a polyampholyte: RADA16. RADA16 is known to self-assemble into nano-fibers formed by -sheet stacking. The self-crosslinking was also mediated by EDC. Results of crosslinking showed formation of polypeptide spherules as well as nano-crystals nominally orthorhombic in shape. It was not possible to ascertain composition of the nano-crystals due to both the limited amount of raw material available and the capabilities of measurement equipment as of this writing. It is hypothesized that nano-crystals are composed of some type of urea by-product from the crosslinking reaction. The spherules, on the other hand, seem to be described by the theory of hydrophobic polyelectrolytes. Additional research conducted with regards to electromagnetic hydrodynamic flows during the time frame of this dissertation is also included. The research uses hydrodynamic conservation equations as a starting point to derive one electromagnetic flow momentum equation analogous to the Cauchy momentum equation of hydrodynamics. It also introduces a mass- energy conservation equation for electromagnetic flow that has no hydrodynamic analogue. We begin this dissertation by introducing in Chapter 1 some of the theoretical background necessary to understand results from experiments. Chapter 2 introduces experimental results from elasticity and viscoelasticity measurements and Chapter 3 explains the dielectric relaxation experiment. We then follow with Chapter 4 which presents conclusions from mechanical and dielectric relaxation experiments in a concise format. Results from the self- crosslinking of RADA16 are presented in Chapter 5. Finally, the additional research on electromagnetic flow is presented in Chapter 6.

A new numerical analysis method, dispersion vs. absorption plots (DISPA), has been developed for ESR. This method may be used for semi-quantitative line-shape studies and is useful both as a diagnostic and analytical tool. In addition it provides a method of automatic phasing for magnetic resonance spectra. Numerous examples of its applications, both simulated and experimental are presented, with emphasis on spin-probe studies. The digital acquisition and processing methods used for these studies are also briefly discussed. ESR and NMR relaxation time studies of the bis(dialkyl-N-carbodithioate) metal(II) class of spin-probes have been performed. The T₁,'s of ¹³C and ²H enriched nickel complex were measured by NMR. The line-widths of ⁶³Cu complex were measured by ESR and analysed by Redfield theory. The two sets of results were combined to give the principal elements of the rotational diffusion tensor for the pyrollidine derivative in toluene. This is the first time that ESR and NMR studies have been combined to measure a diffusion tensor. A general strategy for this approach is presented. ESR data from previous work has been re-analysed in the light of the new results. The analysis shows that the commonly used assumption of isotropic diffusion is extremely misleading. / Science, Faculty of / Chemistry, Department of / Graduate

Chronic back pain has a profound impact on an individual and society. Over the past two decades individuals have become increasingly interested in Complimentary and Alternative Medicine (CAM) as a treatment for medical conditions. One of the most common uses of CAM is to treat back pain. There are a variety of CAM interventions to treat pain, and clinical hypnosis is one treatment that serves to help individuals to better manage their symptoms of chronic pain. In many cases, clinical hypnosis is used as an adjunct to treatment rather than a treatment alternative. Additionally, clinical hypnosis is included as part of relaxation treatments within chronic pain rehabilitation programs across the country. There remains a lack of information on hypnosis as a treatment for chronic back pain within chronic pain rehabilitation programs. The present study assessed pain intensity, disability, and quality of life for individuals who received hypnosis and those who did not in a chronic pain rehabilitation program. Descriptive data were presented for all participants and between groups and within group comparisons were made. Results of this study showed that prior to treatment, pain caused severe disability, was discomforting or distressing, and caused moderate to severe mental and physical impact. When patients returned 6-12 weeks later, all patients reported a decrease in disability and pain and an increase in physical and mental health quality of life. Groups did not vary significantly on measures of pain intensity, disability, and health status. Results of this study suggest that more research should be done on the usefulness of various treatments within interdisciplinary chronic pain rehabilitation programs. Additionally, more research will allow clinicians to gain a better understanding of thetypes of interventions utilized within psychological portions of chronic pain rehabilitation.

A large portion of research in science and engineering, as well as in business, concerns one similar problem: how to make things "better”? Once properly modeled (although usually a highly nontrivial task), this kind of questions can be approached via a mathematical optimization problem. Optimal solution to a mathematical optimization problem, when interpreted properly, might corresponds to new knowledge, effective methodology or good decisions in corresponding application area. As already proved in many success stories, research in mathematical optimization has a significant impact on numerous aspects of human life. Recently, it was discovered that a large amount of difficult optimization problems can be formulated as copositive programming problems. Famous examples include a large class of quadratic optimization problems as well as many classical combinatorial optimization problems. For some more general optimization problems, copositive programming provides a way to construct tight convex relaxations. Because of this generality, new knowledge of copositive programs has the potential of being uniformly applied to these cases. While it is provably difficult to design efficient algorithms for general copositive programs, we study copositive programming from two standard aspects, its relaxations and its separation problem. With regard to constructing computational tractable convex relaxations for copositive programs, we develop direct constructions of two tensor relaxation hierarchies for the completely positive cone, which is a fundamental geometric object in copositive programming. We show connection of our relaxation hierarchies with known hierarchies. Then we consider the application of these tensor relaxations to the maximum stable set problem. With regard to the separation problem for copositive programming. We first prove some new results in low dimension of 5 x 5 matrices. Then we show how a separation procedure for this low dimensional case can be extended to any symmetric matrices with a certain block structure. Last but not least, we provide another approach to the separation and relaxations for the (generalized) completely positive cone. We prove some generic results, and discuss applications to the completely positive case and another case related to box-constrained quadratic programming. Finally, we conclude the thesis with remarks on some interesting open questions in the field of copositive programming.

In this work the relationship between physical properties, such as physical aging and relaxation time distributions, and chemical structure for a variety of polymeric systems were investigated. Although there is a vast amount of physical aging data for polymers, most of these studies do not attempt to correlate structure with physical aging. Therefore, a set of engineering thermoplastics was examined with the goal of relating certain of their characteristic molecular dimensions to their mechanical and volumetric physical aging attributes.Another series of polymeric materials, based on a poly(ether sulfone) backbone, and having various endgroups differing in size, was also studied to determine physical aging rates and relaxation time distributions. Furthermore, it was concluded that the density of the poly(ether sulfones) increased while the glass transition temperature decreased as the endgroup became smaller.Thermoplastic toughened epoxies were also examined to clarify the importance of covalent bonds between toughener and epoxy on physical aging, relaxation time distributions and fracture toughness. In these studies the covalently bonded tougheners differed from their non-reactive counterparts in the rates of volumetric physical aging at high temperatures for the difunctional epoxy. The solvent resistance of the reactive thermoplastic toughened tetrafunctional epoxy was higher than the non-reactive thermoplastic toughened system. The tetrafunctional epoxies with the reactive toughener also had higher toughener glass transition temperatures. / Ph. D.

The present study was designed to determine if Progressive Relaxation exercises would be effective in reducing the response time of a single Parkinsonian on a specific reaction time/movement time took. A 75 year old man served as the subject for this study. He performed a simple response time task at two scheduled sessions per week, for a total of ten weeks. Starting the sixth week, the subject began relaxation training at each session. Data points that represented the average of ten response scores from each session were plotted on a graph and examined by regression analysis. Regression lines representing data points projected to 100 sessions were calculated for both treatment and non-treatment halves. The response time for the one hundredth session, without treatment, was calculated to be .5744 second. The response time for the one hundredth treatment session was .1628 second. Regression analysis indicated that the progressive relaxation program reduced the response time of the subject.