Transient current effects on poly(o-methoxyaniline) films irradiated by pulsed electron beam

Fast transient current decay was recorded on POMA samples during current pulses (in the order of milliseconds) provided by a low energy electron beam under an applied field. The characteristic time decay depends on the electron beam energy and on the bias polarity. The results were explained taking into account the effect of space charge, the intrinsic conductivity of the non-irradiated region of the sample and the radiation-induced conductivity of the thin irradiated region. Fitting parameters may provide the value of both intrinsic and radiation-induced conductivities and the average electron range.

Adsorption processes in layer-by-layer films of poly(o-methoxyaniline): the role of aggregation

In this work we investigate the effect from the solution concentration on aggregation in layer-by-layer (LBL) films of poly(omethoxyaniline) (POMA) alternated with poly(vinyl sulfonic acid). Films are adsorbed on hydrophilized glass substrates and characterized with UV-Vis spectroscopy and atomic force microscopy. The formation of aggregates is favored in more concentrated solutions, leading to an increase in the diameter of the domains. This is caused by stronger polymer-polymer interactions under high concentrations. The size of POMA aggregates in solution is estimated to be larger than in LBL films, which is surprising because one should expect aggregates from solution to coalesce into larger aggregates in the deposited films. This unexpected result may be explained by a swelling effect of aggregates in the aqueous POMA solutions, consistent with other reports in the literature which consider the aggregates in solution to be made up of smaller aggregates. Upon adsorption on a solid substrate to form the LBL film, a molecular reorganization probably takes place, resulting in smaller aggregates. It is also found that the size distribution of the POMA domains in the LBL films is determined by the concentration of the solution. (C) 2002 Elsevier B.V. B.V. All rights reserved.

H-bonding in entrapped water in poly(o-methoxyaniline): Results from a differential scanning calorimetry study

Differential scanning calorimetry (DSC) was used to investigate entrapped water in poly(o-methoxyaniline) (POMA) in powder form. Two endothermic peaks were attributed to removal of water molecules that were adsorbed with distinct energies. By obtaining thermograms at various heating rates, we succeeded in applying Kissinger's approaches to estimate activation energies for the water adsorbed. The values obtained were ca. 25 and 53 kJ/mol, which correspond to H-bonding interactions, probably at the amine and imine centers of POMA, respectively. (C) 2005 Elsevier B.V. All rights reserved.

Preparation and characterization of castor oil-based polyurethane/poly(o- methoxyaniline) blend film

Blends made up of castor oil-based polyurethane (PU) and poly(o-methoxyaniline) (POMA) were obtained in the form of films by casting and characterized by FTIR, UV-Vis-NIR spectroscopy, and electrical conductivity measurements. Doping was carried out by immersing the films in 1.0M HCl aqueous solution. Chemical bonds between NCO group of PU and NH group of POMA were observed by means of FTIR spectra. The UV-Vis-NIR spectra indicated that the presence of the PU in the blend does not affect doping and formation of the POMA phase. The electrical conductivity research was in the range of 10-3 S/cm. © 2007 Wiley Periodicals, Inc.

La facilitación del comercio en las negociaciones comerciales, multilaterales y bilaterales

Incluye Bibliografía

Structure control of poly(p-phenylene vinylene) in layer-by-layer films by deposition on a charged poly(o-methoxyaniline) cushion

In this paper, we demonstrate that the intrinsic electric field created by a poly(o-methoxyaniline) (POMA) cushion layer hinders the changes in molecular conformation of poly(p-phenylenevinylene) (PPV) in layer-by-layer with dodecylbenzene sulfonic acid (DBS). This was modeled with density functional theory (DFT) calculations where an energy barrier hampered molecular movements of PPV segments when they were subjected to an electric field comparable to that caused by a charged POMA layer. With restricted changes in molecular conformation, the PPV film exhibited Franck-Condon transitions and the photoexcitation spectra resembled the absorption spectra, in contrast to PPV/DBS films deposited directly on glass, with no POMA cushion. Other effects from the POMA cushion were the reduced number of structural defects, confirmed with Raman spectroscopy, and an enhanced PPV emission at high temperatures (300 K) in comparison with the films on bare glass. The positive effects from the POMA cushion may be exploited for enhanced opto-electronic devices, especially as the intrinsic electric field may assist in separating photoexcited electron-hole pairs in photovoltaic devices. © 2013 American Institute of Physics.

Parâmetros do estresse oxidativo no soro de cães alimentados com rações suplementadas com óleo de caju, óleo de mamona e óleo de peixe

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento e caracterização de dispositivos luminescentes híbridos

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Desenvolvimento e caracterização de dispositivos de visualização eletroluminescentes

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Estudo das propriedades elétro-óptica de dispositivos eletroluminescentes confeccionados com um compósito híbrido

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

Preparação e caracterização de blendas de poliuretano derivado do óleo de mamona e poli (o-metoxianilina) e sua avaliação como sensor

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)

XVII Reunión de Directores Nacionales de Aduanas de América Latina, España y Portugal; XVI Congreso y exposición de la Federación de Asociaciones Nacionales de Agentes de Carga, en Lima, Perú, en agosto de 1997.

La XVII Reunión de Directores Nacionales de Aduanas de América Latina, España y Portugal, se celebró en Santa Cruz de la Sierra, Bolivia del 27 al 31 de enero de 1997. Participaron representantes de Argentina, Bolivia, Brasil, Chile, Cuba, El Salvador, España, México, Nicaragua, Panamá, Paraguay, Perú, Portugal, República Dominicana, Uruguay y Venezuela. En calidad de observadores participaron representantes de Australia, Estados Unidos, Francia y Japón. Asimismo, concurrieron representantes de los siguientes organismos internacionales: Asociación de Despachantes de Aduanas del Uruguay, Asociación Internacional de Agentes Profesionales de Aduanas (ASAPRA), Asociación Latinoamericana de Integración (ALADI), Banco Interamericano de Desarrollo (BID), Comisión Económica para América Latina y el Caribe (CEPAL), Conferencia de las Naciones Unidas para el Comercio y Desarrollo (UNCTAD), Conferencia Latinoamericana de Empresas Courier (CLADEC), Instituto Centroamericano de Administración de Empresas (INCAE), Junta del Acuerdo de Cartagena (JUNAC), Organización de Estados Americanos (OEA), Organización Mundial de Aduanas (OMA), Unión Postal para las Américas, España y Portugal (UPAEP).

Caracterização por espectroscopia vibracional de filmes Layer-by-Layer contendo ftalocianina, polímeros condutores e gomas naturais

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Estudo de técnicas de análise modal operacional em sistemas sujeitos a excitações aleatórias com a presença de componente harmônico

A metodologia tradicional de identificação de parâmetros na análise modal de estruturas é realizada a partir de sinais medidos de força de entrada e de movimento de resposta da estrutura em condições laboratoriais controladas. Entretanto, quando é necessária a obtenção dos parâmetros modais de estruturas de máquinas em operação, as condições para controlar e medir a excitação nestas situações impossibilita a realização da análise modal tradicional. Neste caso, o teste modal é realizado utilizando somente dados de resposta do sistema. A Análise Modal Operacional (AMO) é um método de extração modal em que nenhuma excitação artificial necessita ser aplicada ao sistema, utilizando-se a própria excitação operacional como entrada para medição da resposta do sistema. A técnica clássica de Análise Modal Operacional NExT considera, para isso, que a excitação operacional do sistema seja um ruído branco. Esta técnica faz a consideração de que as funções de correlação obtidas de estruturas podem ser consideradas como funções de resposta ao impulso e então métodos tradicionais de identificação modal no domínio do tempo podem ser empregados. Entretanto, caso a excitação operacional contenha componentes harmônicos que se sobressaiam, estes podem ser confundidos como modos naturais do sistema. Neste trabalho é demonstrada que através da função densidade de probabilidade da banda estreita contendo o pico de um modo, é possível identifica-lo como natural ou operacional (proveniente da excitação operacional da estrutura). É apresentada também uma modificação no método de identificação modal Exponencial Complexa Mínimos Quadrados (LSCE), passando a considerar sinais harmônicos de freqüências conhecidas presentes na excitação operacional, em um ensaio utilizando a técnica NExT. Para validação desses métodos, utiliza-se um modelo teórico de parâmetros modais conhecidos analiticamente e como estudo de caso experimental, um sistema formado por uma viga bi-apoiada suportando um motor elétrico com desbalanceamento de massa.

Effects of physiotherapy on balance and unilateral vestibular hypofunction in vertiginous elderly

Background: We aimed to analyze the effect of a physical therapy protocol on unilateral vestibular hypofunction and overall balance in elderly with vertigo. Methods: The study included nine subjects, four male subjects (68.5 ± 11.09 years old) and five females (72.4 ± 7.09 years old). It was used the performance-oriented Mobility Assessment (POMA), to evaluate the balance and the Unterberger – Fukuda test for analysis of unilateral vestibular dysfunction through rotations and displacements of the body. We developed and applied a structured physical therapy protocol, consisting of group exercises. Results: It was observed that after the protocol, all participants improved balance (33.9 ± 5.1 vs. 47.3 ± 7.6, p < 0.0001) and displacement (111.1 ± 38.0 vs. 53.3 ± 34.6, p = 0.0001). However, it was not found significant differences for rotation. Conclusion: The proposed protocol has contributed to an improvement in balance and vestibular dysfunction of the aged.