by Fong Kai-io. / Bibliography : leaves 146-147 / Thesis (M.Phil.)--Chinese University of Hong Kong, 1982

Thesis--University of Wisconsin--Madison. / Typescript. Vita. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references.

Thesis--Wisconsin. / Vita. Includes bibliographical references (leaves 145-160).

Dielectric dispersion has been observed in the symmetric-top molecules CHF₃ and CH₃­F in the gas phase over a density range from 10­³ to 40 amagats at a temperature of 309°K and a frequency of 30 MHz. The absorption (related to the dispersion by the Kramers-Kronig relations) has been expressed in terms of a simple correlation function of the permanent electric dipole moment which is the product of the correlation function for free motion and an exponentially decaying "reduced" correlation function. The effects of molecular collisions were described by a single correlation time which measures the apparent molecular diameter. The results were compared with microwave nonresonant absorption and nuclear spin relaxation experiments done on the same molecules. At low densities (<.l amagats) a dispersion curve of the Debye type was observed. At high densities (>1 amagat) the dependence of the dielectric susceptibility on density deviated from that expected from the Clausius-Mossotti equation. The origin of this effect is not understood at present. / Science, Faculty of / Physics and Astronomy, Department of / Graduate

No description available.

Thesis (Ph. D.)--Virginia Polytechnic Institute and State University, 1994. / Vita. Abstract. Includes bibliographical references (leaves 136-141). Also available via the Internet.

The chloride current-voltage characteristics of the membrane of sartorius fibers from Xenopus laevis were studied using a three microelectrode voltage clamp system. In fibers with normal resting potentials (-70 to -90 mV) and in fibers depolarized in 115 mM KC1 (resting potential -20 mV) the direction and degree of steady state rectification depended on extracellular pH. In alkaline solutions (pH 8.4) the current rectified outwards; with large hyperpolarizations the current recorded in normally polarized fibers was sometimes seen to diminish as the voltage was made extremely negative (the current-voltage relation exhibited a negative slope). In the depolarizing region (in depolarized fibers) the slope of the I-V relation became constant (limiting conductance) in alkaline solutions. In acid solutions (pH 5.4) the current rectified inwards with hyperpolarization and reached a limiting value with depolarization. Chloride currents decay ('inactivate') following changes of membrane potential from the resting potential (for both polarized and depolarized fibers). The kinetics of current relaxation exhibited voltage-dependent time constants depending on the size of the voltage step with a sensitivity of about -1.5 msec/mV but were independent of absolute membrane potential and external pH. Inactivation of chloride conductance was studied in two-pulse (conditioning (v₁) and test (V₂), pulses) voltage clamp experiments. In variable experiments the dependence of the initial current at the onset of was sigmoidally related to (inactivation relation). The slope of the inactivation relation was twice as steep in acid as in alkaline solutions, but was independent of the resting potential. In variable V₂ experiments, the current-voltage relation was linear over a wide voltage range and for different values of V₁, the instantaneous I-V relations converged in the outward current region; they also had zero-current potentials that became increasingly negative with respect to the holding potential as V₁ was made negative. Instantaneous chloride currents and the kinetics of current relaxation were found to depend on initial conditions when the membrane potential was changed under non-stationary conditions. The inactivation and recovery of initial current had similar timecourses as did the prolongation and recovery of the time constants. Initial currents recovered from conditioning with an exponential or sigmoid timecourse. Relaxation time constants exhibited a similar recovery pattern. The decline of initial current was initially exponentially dependent on the duration of conditioning. The time constant increased sigmoidally, or exponentially as the duration of conditioning increased. Using the data from variable conditioning step and variable test step experiments a manifold (or state space representation) was constructed that enables much of the current-voltage behavior of the chloride permeation system to be predicted. Currents recorded in voltage clamp experiments can be visualized as time-dependent flows along trajectories that are determined by the voltage. The rectification of the steady state and instantaneous current-voltage relations are related to the dispersion of the trajectories. The dependence of time constants of current transients can also be accounted for by the manifold. The results are examined in light of models for channel behavior. The instantaneous I-V characteristics exhibit some properties of channels of the electrodiffusion type. The steady state current-voltage relations are qualitatively similar to those of a model incorporating a particle within the chloride channel that either blocks or unblocks it depending on the extracellular pH. The dependence of relaxation kinetics on the size of the voltage step and on initial conditions suggest the participation of a molecule acting in a catalytic role controlling the relaxation of current transients. / Science, Faculty of / Mathematics, Department of / Unknown

The frequency dependence and temperature dependence of the complex dielectric constant of water is of great interest. The temperature dependence of the physical properties of water given in the literature, specific heat, thermal conductivity, electric conductivity, pH, etc. are compared to the a. c. (microwave) and d. c. conductivity of water with a variety of concentration of different substances such as HC1, NaCl, HaS04, etc. When each of these properties is plotted versus inverse absolute temperature, it can be seen that each sample shows "transition temperatures". In this work, Slater's perturbation equations for a resonant microwave cavity were used to analyze the experimental results for the microwave data.

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.

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.