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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.
1

Desenvolvimento de um material t?xtil termosenss?vel com micro/nanoc?psulas imobilizadas em fibras regeneradas

S?, Christiane Siqueira de Azevedo 20 February 2015 (has links)
Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-03-09T23:24:53Z No. of bitstreams: 1 ChristianeSiqueiraDeAzevedoSa_DISSERT.pdf: 2601824 bytes, checksum: 192560f3b8d14a03aa0da8a4f6dc9924 (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-03-11T22:01:19Z (GMT) No. of bitstreams: 1 ChristianeSiqueiraDeAzevedoSa_DISSERT.pdf: 2601824 bytes, checksum: 192560f3b8d14a03aa0da8a4f6dc9924 (MD5) / Made available in DSpace on 2016-03-11T22:01:19Z (GMT). No. of bitstreams: 1 ChristianeSiqueiraDeAzevedoSa_DISSERT.pdf: 2601824 bytes, checksum: 192560f3b8d14a03aa0da8a4f6dc9924 (MD5) Previous issue date: 2015-02-20 / Coordena??o de Aperfei?oamento de Pessoal de N?vel Superior - CAPES / Os materiais t?xteis inteligentes e funcionais t?m sido amplamente desenvolvidos e pesquisados com a finalidade de serem utilizados em v?rias ?reas da ci?ncia e tecnologia. Esses materiais fibrosos necessitam de diferentes propriedades qu?micas e f?sicas para se tornarem materiais multifuncionais. Com o advento da nanotecnologia, as t?cnicas desenvolvidas t?m sido ferramentas essenciais para caracterizar qualitativamente esses novos materiais. Ultimamente a aplica??o de micro e nanomateriais em substratos t?xteis tem sido objeto de muitas pesquisas. Muitos desses nanomateriais n?o tem sido otimizado, e os custos para sua aplica??o e a polui??o ao meio ambiente vem aumentando, pois ainda n?o existe tratamento de efluentes contento esses nanomateriais. As fibras de soja t?m baixa adsor??o de micro e nanoc?psulas termosenss?veis devido a sua incompatibilidade de suas cargas superficiais. No presente trabalho utilizou-se a s?ntese da quitosana para previamente funcionalizar as fibras de soja. A quitosana ? um polieletr?lito natural apresentando alta densidade de cargas positivas, as fibras de soja apresentam cargas negativas bem como, as micro/nanoc?psulas, com isso a quitosana atua como agente cationizador da fibra. Neste caso a quitosana atua como agente auxiliar cationizador para fixar as microc?psulas termosenss?veis no substrato t?xtil. Para a caracteriza??o do polieletr?lito foram feitas as an?lises do tamanho das part?culas, potencial zeta, bem como as an?lises morfol?gicas (MEV e DRX), an?lises das propriedades t?rmicas (TG), an?lise da Calorimetria Explorat?ria Diferencial (DSC), an?lise por Espectroscopia na Regi?o do Infravermelho com Transformada de Fourier (FTIR), colorimetria via espectro de UV-VIS foram simultaneamente realizadas no substrato utilizado. No potencial zeta e na determina??o do tamanho das part?culas foi observada a estabilidade eletrost?tica da quitosana em torno de 31.55mV e 291,0 nm respectivamente. O resultado obtido com (GD) para o material extra?do de camar?o foi de 70%, que de acordo com a literatura pode ser considerada como quitosana. Para otimiza??o do processo de tingimento foi usado um software estat?stico, o Design expert. A funcionaliza??o do substrato t?xtil com 2% de quitosana apresentou o melhor resultado de K/S, sendo o par?metro utilizado para o planejamento experimental juntamente com as vari?veis, tendo demonstrado a melhor resposta de tingimento na faixa de 2,624 de absorb?ncia. Verificou-se tamb?m que a malha de soja tingida com as nano/microc?psulas termosenss?veis apresentou excelente propriedade de solidez a lavagem, que foi observada ap?s 25 lavagens caseiras e valores significativos de K/S. / Intelligent and functional Textile Materials have been widely developed and researched with the purpose of being used in several areas of science and technology. These fibrous materials require different chemical and physical properties to obtain a multifunctional material. With the advent of nanotechnology, the techniques developed, being used as essential tools to characterize these new materials qualitatively. Lately the application of micro and nanomaterials in textile substrates has been the objective of many studies, but many of these nanomaterials have not been optimized for their application, which has resulted in increased costs and environmental pollution, because there is still no satisfactory effluent treatment available for these nanomaterials. Soybean fiber has low adsorption for thermosensitive micro and nanocapsules due to their incompatibility of their surface charges. For this reason, in this work initially chitosan was synthesized to functionalise soybean fibres. Chitosan is a natural polyelectrolyte with a high density of positive charges, these fibres have negative charges as well as the micro/nanoc?psules, for this reason the chitosan acts as auxiliary agent to cationize in order to fix the thermosensitive microcapsules in the textile substrate. Polyelectrolyte was characterized using particle size analyses and the measurement of zeta potential. For the morphological analysis scanning Electron Microscopy (SEM) and x-Ray Diffraction (XRD) and to study the thermal properties, thermogravimetric analysis (TGA), Differential Scanning Calorimetry (DSC), Near Infrared Spectroscopy analysis in the Region of the Fourier Transform Infrared (FTIR), colourimetry using UV-VIS spectrum were simultaneously performed on the substrate. From the measurement of zeta potential and in the determination of the particle size, stability of electrostatic chitosan was observed around 31.55mV and 291.0 nm respectively. The result obtained with (GD) for chitosan extracted from shrimp was 70 %, which according to the literature survey can be considered as chitosan. To optimize the dyeing process a statistical software, Design expert was used. The surface functionalisation of textile substrate with 2% chitosan showed the best result of K/S, being the parameter used for the experimental design, in which this showed the best response of dyeing absorbance in the range of 2.624. It was noted that soy knitting dyed with the thermosensitive micro andnanocapsules property showed excellent washing solidity, which was observed after 25 home washes, and significant K/S values.
2

Desenvolvimento de uma formula??o c?lon espec?fica visando o tratamento da colite ulcerativa

Nagashima Junior, Toshiyuki 05 February 2009 (has links)
Made available in DSpace on 2014-12-17T14:13:28Z (GMT). No. of bitstreams: 1 ToshiyukiNJ.pdf: 11006628 bytes, checksum: da763274130c0b79f55fd708108d98c7 (MD5) Previous issue date: 2009-02-05 / Micro and nanoparticulate systems as drug delivery carriers have achieved successful therapeutic use by enhancing efficacy and reducing toxicity of potent drugs. The improvement of pharmaceutical grade polymers has allowed the development of such therapeutic systems. Microencapsulation is a process in which very thin coatings of inert natural or synthetic polymeric materials are deposited around microsized particles of solids or around droplets. Products thus formed are known as microparticles. Xylan is a natural polymer abundantly found in nature. It is the most common hemicellulose, representing more than 60% of the polysaccharides existing in the cell walls of corn cobs, and is normally degraded by the bacterial enzymes present in the colon of the human body. Therefore, this polymer is an eligible material to produce colon-specific drug carriers. The aim of this study was to evaluate the technological potential of xylan for the development of colon delivery systems for the treatment of inflammatory bowel diseases. First, coacervation was evaluated as a feasible method to produce xylan microcapsules. Afterwards, interfacial cross-linking polymerization was studied as a method to produce microcapsules with hydrophilic core. Additionally, magnetic xylan-coated microcapsules were prepared in order to investigate the ability of producing gastroresistant systems. Besides, the influence of the external phase composition on the production and mean diameter of microcapsules produced by interfacial cross-linking polymerization was investigated. Also, technological properties of xylan were determined in order to predict its possible application in other pharmaceutical dosage forms / Os sistemas micro e nanoparticulados t?m sido cada vez mais utilizados por promoverem um aumento da efic?cia de um determinado medicamento bem como redu??o da toxicidade de f?rmacos potentes. A descoberta e pesquisa de materiais polim?ricos, naturais e sint?ticos, permitiram o desenvolvimento de in?meros sistemas terap?uticos. A microencapsula??o ? um processo com o qual finas camadas de um revestimento constitu?das de uma mat?ria prima polim?rica inerte, de origem natural ou sint?tica, s?o depositadas ao redor de part?culas s?lidas micronizadas ou got?culas. A xilana ? um pol?mero natural abundantemente encontrado na natureza, representando mais de 60% dos polissacar?deos presentes na parede celular dos vegetais de grande porte, entre eles o sabugo de milho. Ela ? normalmente digerida em n?vel de c?lon durante a degrada??o residual de carboidratos, realizada por um conjunto de enzimas bacterianas existentes no trato gastro intestinal. Desta maneira, este pol?mero tornou-se uma mat?ria prima eleg?vel para o desenvolvimento de carreadores c?lon espec?ficos. O objetivo deste estudo foi avaliar o potencial tecnol?gico da xilana para o desenvolvimento de uma formula??o visando a libera??o de f?rmacos no c?lon para o tratamento de dist?rbios inflamat?rios intestinais. Inicialmente, foi avaliado a capacidade de xilana formar micropart?culas pela t?cnica da coacerva??o. Posteriormente, foi estudada uma nova t?cnica de obten??o de microc?psulas com n?cleo hidrof?lico pela t?cnica da reticula??o polim?rica interfacial. Depois, sua habilidade de formar sistemas gastrorresistentes foi avaliada com as micropart?culas magn?ticas, em seguida, foi avaliada a influ?ncia da composi??o da fase externa na produ??o e di?metro m?dio das microc?psulas de xilana produzidas por reticula??o interfacial, bem como as propriedades tecnol?gicas da xilana, visando a sua aplica??o em outras formas farmac?uticas
3

An?lise da performance de sistemas de comunica??o sem fio baseados em OFDM utilizando um modelo de propaga??o na ?rea urbana de S?o Paulo - SP

Almeida, Karine Souza de 24 May 2016 (has links)
Submitted by Carolina Neves (carolinapon@uefs.br) on 2016-08-09T01:01:22Z No. of bitstreams: 1 Karine_Souza_de_Almeida_Dissertacao_Final.pdf: 13569698 bytes, checksum: 81752dfa3be4ee9493654f5c61524c5a (MD5) / Made available in DSpace on 2016-08-09T01:01:22Z (GMT). No. of bitstreams: 1 Karine_Souza_de_Almeida_Dissertacao_Final.pdf: 13569698 bytes, checksum: 81752dfa3be4ee9493654f5c61524c5a (MD5) Previous issue date: 2016-05-24 / Funda??o de Amparo ? Pesquisa do Estado da Bahia - FAPEB / By using the Orthogonal Frequency Division Multiplexing (OFDM), it is possible to transmit by a channel a more robust signal and less susceptible to interferences. When such technique, based on orthogonal subcarriers, is combined with the use of propagation models, which are relevant tools for simulating the signal behavior in respect to environmental parameters and antenna configurations, it is feasible to have an evaluation about the performance of these systems, improving their project phase. Therefore, this work presents the use of OFDM technique applied to two propagation models: a two-ray geometric model and a microcellular model adapted to the Paulista Avenue, S?o Paulo, SP, having as objective the analysis of a mobile communication system through Bit Error Rate (BER). In the developed application using the MAtrix LABoratory (MATLAB) software, the mobile communication system based on OFDM admits several scenarios during the simulation, so that scenarios are related to positioning of the antennas, heights, type of modulation, size of the bit sequence to be sent, and others. The adopted OFDM architecture has been the IFFT/FFT and based on it, the system performs the transmission and reception of a bit set through a channel with interference by using different digital modulations, making appropriate comparisons. / Atrav?s da utiliza??o da t?cnica de Multiplexa??o por Divis?o de Frequ?ncias Ortogonais (OFDM, do ingl?s, Orthogonal Frequency Division Multiplexing), ? poss?vel transmitir por um canal um sinal mais robusto e menos propenso a interfer?ncias. Quando tal t?cnica, baseada na utiliza??o de subportadoras ortogonais, ? aliada ao uso de modelos de propaga??o, que s?o ferramentas relevantes para a simula??o do comportamento do sinal em rela??o aos par?metros do ambiente e as configura??es das antenas, ? poss?vel ter uma avalia??o a respeito do desempenho desses sistemas, melhorando a fase de projeto dos mesmos. Sendo assim, este trabalho apresenta o uso da t?cnica OFDM aplicada a dois modelos de propaga??o: um modelo geom?trico de dois raios e um modelo microcelular adaptado para a Avenida Paulista, S?o Paulo, SP, possuindo como objetivo a an?lise de um sistema de comunica??o m?vel atrav?s do c?lculo da Taxa de Erro de Bit (BER, do ingl?s, Bit Error Rate). Na aplica??o desenvolvida utilizando o software MATLAB (MATrix LABoratory), o sistema de comunica??o m?vel baseado em OFDM assume diversos cen?rios durante as simula??es, de forma que esses cen?rios s?o relacionados ao posicionamento das antenas, alturas, tipo de modula??o, tamanho da sequ?ncia de bits a ser enviada, entre outras. A arquitetura OFDM adotada foi a IFFT/FFT e baseado nela, o sistema realiza a transmiss?o e a recep??o de um conjunto de bits por um canal com interfer?ncias utilizando diferentes modula??es digitais, fazendo as devidas compara??es.
4

Problematika přechodu od jednojádrové k vícejádrové implementaci operačního systému / Issue of Migrating from Single-Core to Multi-Core Implementation of Operating System

Matyáš, Jan January 2014 (has links)
This thesis discuss necessary changes needed in order to run MicroC/OS-II on multicore processor, mainly Zynq 7000 All Programmable SoC which uses two ARM Cortex-A9 cores. Problems that arise during this transition are also discussed.
5

Novos sistemas de libera??o de f?rmacos ? base de xilana

Oliveira, Elquio Eleamen 07 June 2010 (has links)
Made available in DSpace on 2014-12-17T14:13:33Z (GMT). No. of bitstreams: 1 ElquioEO_TESE.pdf: 1649953 bytes, checksum: 1098cd34b1d3e6c9a180949d25fa8185 (MD5) Previous issue date: 2010-06-07 / Universidade Federal do Rio Grande do Norte / The aim of this work was to perform the extraction and characterization of xylan from corn cobs and prepare xylan-based microcapsules. For that purpose, an alkaline extraction of xylan was carried out followed by the polymer characterization regarding its technological properties, such as angle of repose, Hausner factor, density, compressibility and compactability. Also, a low-cost and rapid analytical procedure to identify xylan by means of infrared spectroscopy was studied. Xylan was characterized as a yellowish fine powder with low density and poor flow properties. After the extraction and characterization of the polymer, xylan-based microcapsules were prepared by means of interfacial crosslinking polymerization and their characterization was performed in order to obtain gastroresistant multiparticulate systems. This work involved the most suitable parameters of the preparation of microcapsules as well as the study of the process, scale-up methodology and biological analysis. Magnetic nanoparticles were used as a model system to be encapsulated by the xylan microcapsules. According to the results, xylan-based microcapsules were shown to be resistant to several conditions found along the gastrointestinal tract and they were able to avoid the early degradation of the magnetic nanoparticles / O presente trabalho teve como objetivo a extra??o e caracteriza??o do pol?mero de xilana a partir de res?duos de sabugo de milho e a produ??o de microc?psulas a partir deste pol?mero. O primeiro passo foi a extra??o da xilana em meio alcalino e caracteriza??o deste pol?mero quanto as suas propriedades tecnol?gicas (?ngulo de repouso, fator de Hausner, densidade, compressibilidade e compactabilidade), bem como a elabora??o de uma procedimento r?pido e barato para a identifica??o deste pol?mero atrav?s de espectroscopia de absor??o na regi?o do infravermelho. O pol?mero de xilana foi caracterizado como sendo um p? de cor amarelada de baixa densidade e com propriedades de escoamento pouco favor?veis. Ap?s a obten??o e caracteriza??o do pol?mero, microc?psulas de xilana foram preparadas atrav?s da reticula??o polim?rica interfacial e caracterizadas a fim de se obter sistemas multiparticulados gastroresistentes. O trabalho foi delineado buscando-se os melhores fatores na t?cnica de prepara??o das microc?psulas, assim como o estudo do processo, aumento de escala e avalia??o biol?gica. Nanopart?culas magn?ticas foram utilizadas como sistema modelo a ser encapsulado pelas microc?psulas ? base de xilana. Os resultados obtidos demonstraram que as microc?psulas de xilana s?o resistentes ?s diversas condi??es encontradas ao longo do trato gastrintestinal e foram capazes de evitar a degrada??o pr?via das nanopart?culas magn?ticas in vitro

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