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Avaliação de propriedades de artefatos à base de borracha natural / Evaluation of the properties of articles based on natural rubberJanaina Dallas Caroline Bárbara di Kássia Fonseca da Silva 18 June 2007 (has links)
A combinação de excelentes propriedades mecânicas aliadas à biocompatibilidade torna a borracha natural um material amplamente empregado na fabricação de artefatos voltados à saúde, tais como bicos de chupetas e de mamadeiras, e luvas cirúrgicas e de procedimentos não-cirúrgicos. Esses artefatos são processados a partir de látices de poli(cis-isopreno) extraído de seringueiras. Entretanto, o grande número de insaturações presentes na cadeia polimérica, mesmo após a vulcanização, resulta em uma baixa resistência desse material ao envelhecimento, causado principalmente pela associação de fatores como temperatura, oxigênio, ozônio e radiação. Outro inconveniente associado à aplicação da borracha natural é a presença de proteínas no látex, com potencial alergênico, podendo promover reações fisiológicas em alguns usuários. Por esse motivo artefatos comerciais à base de material sintético também são encontrados no mercado. Esses artefatos também não são isentos dos processos naturais de desgaste e decomposição. Esta Dissertação teve como objetivo realizar um estudo comparativo de propriedades dos produtos comerciais à base de borracha natural e à base de material sintético (bicos de chupeta e de mamadeiras e luvas) de diferentes fabricantes, como adquiridos e após sofrerem envelhecimento acelerado. O estudo foi feito empregando-se as técnicas de espectroscopia na região do infravermelho com transformada de Fourier (FTIR) e termogravimetria (TG). Uma avaliação mecânica com métodos padronizados foi também realizada / By combining the excellent mechanical properties as well as biocompatibility, natural rubber is a suitable material to be applied in the manufacture of commercial articles as pacifiers, nursing bottles and gloves. Those products are processed from lattices of poly(cis-isoprene) extracted from rubber-trees. Nevertheless, the expressive amount of insaturations present along the polymeric chains, even after the vulcanization process, leads to degradation mainly caused by an association of factors as heat, oxygen, ozone and radiation. Another inconvenience in the application of natural rubber is the presence of some proteins in the latex, which causes allergic problems in a few usuaries. Thus synthetic materials are also employed in the production of such articles that are not free from degradation problems as well. The objective of this Dissertation was to carry out a comparative study of some properties of commercial products (nipples, of pacifiers and nursing bottles, and gloves) from different manufacturers. The materials were characterized, as received and after being submitted to accelerated degradation, by infrared spectroscopy (FTIR) and thermogravimetry (TG). Some mechanical properties were also evaluated by employing standard methods
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Unfettering the Political Mandate: Reflections on Political Prohibition, The World Bankâs Role in the Protection of Human Rights and the Chad â Cameroon Pipeline.Kirunda, Robert. January 2008 (has links)
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<p align="left">As a case study, the paper analyzes the Bank&rsquo / s role in the Chad-Cameroon Petroleum Development and Oil Pipeline project (the project) in which the Bank has been involved since the year 2000. The paper presents the lessons, challenges and implications from this protection of human rights.</p>
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Get published! Straight talk from the editors at PartnershipFox, David, Kandiuk, Mary, Smith, Ann 31 January 2013 (has links)
This presentation covers the origin, history and scope of Partnership: the Canadian Journal of Library and Information Practice and Research; the editorial process and timeframes; research and scholarship for librarians; the peer review process; the components of a good research article; practical tips on what editors look for in a manuscript submission with examples from Partnership journal. The presentation is intended for anyone writing a research article but should be particularly helpful to first-time authors.
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Swarm Control Through Symmetry and Distribution CharacterizationDinolov, Georgi 01 May 2011 (has links)
Two methods for control of swarms are described. The first of these methods, the Virtual Attractive-Repulsive (VARP) method, is based on potentials defined between swarm elements. The second control method, or the abstraction method, is based on controlling the macroscopic characteristics of a swarm. The derivation of a new control law based on the second method is described. Numerical simulation and analytical interpretation of the result is also presented.
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Get Published! Straight Talk from the Editors at PartnershipFox, David 31 January 2013 (has links)
This paper covers the origin, history and scope of Partnership: The Canadian Journal of Library and Information Practice and Research, the editorial process and timeframes, research and scholarship for librarians, the peer review process, the components of a good research article, and practical tips on what editors look for in a manuscript submission with examples from Partnership journal. It is intended for anyone writing a research article but should be particularly helpful to first-time authors. The paper was first given as a presentation at Ontario Library Association Super Conference on January 31, 2013. / Ontario Library Association
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The link between informational efficiency and economic efficiency : essays on corporate disclosure policy and private information acquisition /Dierker, Martin Johannes. January 2003 (has links) (PDF)
Calif., Univ. of California, Diss.--Los Angeles, 2003. / Kopie, ersch. im Verl. UMI, Ann Arbor, Mich. - Enth. 3 Beitr.
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Essays on changes in social norms and their macroeconomic implications /Giuliano, Paola. January 2003 (has links) (PDF)
Calif., Univ. of California, Diss.--Berkeley, 2003. / Kopie, ersch. im Verl. UMI, Ann Arbor, Mich. - Enth. 2 Beitr.
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Essays on corporate finance : studies on takeover announcement and IPO lockup expiration /Gao, Yuan. January 2005 (has links) (PDF)
NY, Cornell Univ., Diss.--Ithaca, 2005. / Kopie, ersch. im Verl. UMI, Ann Arbor, Mich. - Enth. 2 Beitr.
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Essays on institutions and fiscal policy in the American states /Rose, Shanna Suzanne. January 2005 (has links) (PDF)
Mass., Harvard Univ., Diss.--Cambridge, 2005. / Kopie, ersch. im Verl. UMI, Ann Arbor, Mich. - Enth. 3 Beitr.
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An empirical study of momentum and reversal in United States equity market /Wang, Jun. January 2005 (has links) (PDF)
NJ, Rutgers State Univ. of New Jersey, Diss.--Newark, 2005. / Kopie, ersch. im Verl. UMI, Ann Arbor, Mich. - Enth. 2 Beitr.
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