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A Study of the Scope, Limitations and Kinetics of the Siliconization of Triarylamines Using Tris(pentafluorophenyl)borane CatalysisGretton, Michael James 20 November 2012 (has links)
Piers-Rubinsztajn (P-R) conditions, involving catalysis by tris(pentafluorophenyl)borane, were applied to siliconize triarylamines. A phenylated linear methylhydrosiloxane copolymer was utilized to create a hydrolytically-stable composite with promising optical, electrochemical and thermal properties. However, the reaction was highly exothermic, had rapid uncontrollable kinetics and produced methane as a byproduct; problematic characteristics for larger scale syntheses. Thereafter, triarylamines with bulkier substituents were studied to determine whether the kinetics could be slowed and a less volatile byproduct created. The rate of conversion was retarded significantly as expected, but not all derivatives reacted quantitatively in ambient conditions. Finally, P-R conditions were applied to methylhydrosiloxane-dimethylsiloxane copolymers. Gelation in air upon extended reaction time was effectively avoided by “finishing” excess Si-H sites using anisole. The result was the preparation of composites with up to 61 wt % arylamine content, which are expected to have significant applications as cost-effective flexible hole transport layers in organic electronic devices.
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A Study of the Scope, Limitations and Kinetics of the Siliconization of Triarylamines Using Tris(pentafluorophenyl)borane CatalysisGretton, Michael James 20 November 2012 (has links)
Piers-Rubinsztajn (P-R) conditions, involving catalysis by tris(pentafluorophenyl)borane, were applied to siliconize triarylamines. A phenylated linear methylhydrosiloxane copolymer was utilized to create a hydrolytically-stable composite with promising optical, electrochemical and thermal properties. However, the reaction was highly exothermic, had rapid uncontrollable kinetics and produced methane as a byproduct; problematic characteristics for larger scale syntheses. Thereafter, triarylamines with bulkier substituents were studied to determine whether the kinetics could be slowed and a less volatile byproduct created. The rate of conversion was retarded significantly as expected, but not all derivatives reacted quantitatively in ambient conditions. Finally, P-R conditions were applied to methylhydrosiloxane-dimethylsiloxane copolymers. Gelation in air upon extended reaction time was effectively avoided by “finishing” excess Si-H sites using anisole. The result was the preparation of composites with up to 61 wt % arylamine content, which are expected to have significant applications as cost-effective flexible hole transport layers in organic electronic devices.
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Formation, characterization and flow dynamics of nanostructure modified sensitive and selective gas sensors based on porous siliconOzdemir, Serdar 29 March 2011 (has links)
Nanopore covered microporous silicon interfaces have been formed via an electrochemical etch for gas sensor applications. Rapid reversible and sensitive gas sensors have been fabricated. Both top-down and bottom-up approaches are utilized in the process. A nano-pore coated micro-porous silicon surface is modified selectively for sub-ppm detection of NH3, PH3, NO, H2S, SO2. The selective depositions include electrolessly generated SnO2, CuxO, AuxO, NiO, and nanoparticles such as TiO2, MgO doped TiO2, Al2O3, and ZrO2. Flow dynamics are analyzed via numerical simulations and response data. A general coating selection method for chemical sensors is established via an extrapolation on the inverse of the Hard-Soft Acid-Base concept.
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Reliability of SiGe HBTs for extreme environment and RF applicationsCheng, Peng 17 November 2010 (has links)
The objective of the proposed research is to characterize the safe-operating-area of silicon-germanium (SiGe) heterojunction bipolar transistors (HBTs) under radiofrequency (RF) operation and extreme environments. The degradation of SiGe HBTs due to mixed-mode DC and RF stress has been modeled for the first time. State-of-the-art 200 GHz SiGe HBTs were first characterized, and then DC and RF stressed. Excess base leakage current was modeled as a function of the stress current and voltage. This physics-based stress model was then designed as a
sub-circuit in Cadence, and incorporated into SiGe power amplifier design to predict the
DC and RF stress-induced excess base current. Based on these studies, characterization of
RF safe-operating-area for SiGe HBTs using devices and circuits is proposed.
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A case series study of Vitapex® pulpectomy treatment in primary teeth IIHsieh, Hsin-Ju. January 2007 (has links) (PDF)
Thesis (M.S.)--University of Alabama at Birmingham, 2007. / Title from first page of PDF file (viewed Feb. 5, 2008). Includes bibliographical references (p. 71-79).
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Absortion, déposition et effet prophylactique de trois composés organiques de silicium dans le pathosysteme blé-blanc /Côté Beaulieu, Caroline. January 2008 (has links)
Thèse (M.Sc.)--Université Laval, 2008. / Bibliogr.: f. [42]-45. Publié aussi en version électronique dans la Collection Mémoires et thèses électroniques.
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Accuracy of addition silicone impression materials as a function of technic a thesis submitted in partial fulfillment ... in dental materials /Johnson, Glen H. January 1983 (has links)
Thesis (M.S.)--University of Michigan, 1983.
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Accuracy of addition silicone impression materials as a function of technic a thesis submitted in partial fulfillment ... in dental materials /Johnson, Glen H. January 1983 (has links)
Thesis (M.S.)--University of Michigan, 1983.
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Análise da resposta celular e inflamatória associada ao tecido conjuntivo neoformado induzida pela implantação subcutânea de prótese de silicone texturizada ou revestida com poliuretano em ratasVieira, Vilberto José 16 July 2013 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde, Programa de Pós-Graduação em Ciências Médicas, Florianópolis, 2010 / Made available in DSpace on 2013-07-16T04:00:08Z (GMT). No. of bitstreams: 1
281827.pdf: 3805193 bytes, checksum: 59c6cc4748dab0785a44baad97af5721 (MD5) / A contratura capsular é a complicação mais comum associada ao uso de implantes mamários de silicone. A superfície do implante é um dos fatores associados à ocorrência de contratura capsular. Este estudo experimental avaliou as diferenças nas características morfológicas e moleculares da cápsula formada ao redor de implantes revestidos de poliuretano comparados aos de superfície texturizada em ratas Wistar, principalmente as modificações na angiogênese, na expressão do VEGF e sua relação com os níveis de TGF-? e ?-SMA. As cápsulas dos implantes revestidos de poliuretano foram significativamente mais espessas do que as de superfície texturizada nos dois períodos avaliados. Essa diferença ocorreu principalmente às custas do tecido conjuntivo neoformado. O tecido conjuntivo neoformado adjacente aos implantes revestidos de poliuretano foi mais celular, irregular e vascularizado quando comparado aos implantes de superfície texturizada. As fibras de colágeno nos implantes texturizados aparentam ser mais contínuas e alinhadas em relação aos implantes revestidos de poliuretano. A análise imunohistoquímica revelou elevados níveis de TGF-? e VEGF nas cápsulas em torno dos implantes revestidos por poliuretano quando comparados aos de superfície texturizada. Não se evidenciou diferença na expressão de ?-SMA, entre os implantes revestidos de poliuretano e texturizados após 90 dias. Esses achados sugerem que a maior expressão de VEGF ao redor das próteses induzidas pelos cristais de poliuretano teria a capacidade de aumentar a vascularização tissular, resultando numa cápsula mais macia se comparada aos implantes de superfície texturizada.
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Estudo histológico da reação inflamatória ao implante de silicone revestido com poliuretano em ratosMendes, Paulo Roberto da Silva January 2002 (has links)
Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro de Ciências da Saúde. Curso de Pós-Graduação em Ciências Médicas. / Made available in DSpace on 2012-10-20T09:43:21Z (GMT). No. of bitstreams: 0Bitstream added on 2014-09-26T01:40:29Z : No. of bitstreams: 1
182526.pdf: 9813265 bytes, checksum: 6c46888eebe43be40a4ca4cc278aad0d (MD5) / Introdução: A procura de um substituto para a glândula mamária, tem longa história de insucessos até o advento dos implantes de silicone. A contratura capsular é uma das complicações mais comuns, e a presença de contaminação bacteriana do sítio operatório, tem sido indicada como seu principal fator etiológico. As alterações histológicas peri-implantes são escassas na literatura.
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