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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.
61

Propriedades espectroscópicas do ácido orto-aminobenzóico: estudo computacional e experimental de efeitos de pH / Spectroscopic properties of the ortho-aminobenzoic acid: An computational and experimental study of the effects of pH.

Olivier, Danilo da Silva 26 March 2012 (has links)
A molécula de ácido orto-aminobenzóico tem sido intensamente empregada como sonda fluorescente no estudo de peptídeos e membranas e o entendimento dos efeitos de solvente sobre suas propriedades espectroscópicas apresenta grande interesse científico. Neste trabalho realizamos um estudo experimental e cálculos DFT sobre alterações nos espectros de absorção e emissão da sonda em solução aquosa, em função do pH do meio. Examinamos também o seu derivado 2-amino-N-metil benzamida (o-Abz-NHCH3) e as mudanças espectrais na interação com micelas de SDS. Resultados de experimentos de titulação mostraram-se coerentes com a existência de três estados de protonação para o-Abz à medida em que o pH torna-se ácido, resultantes da protonação dos grupos amino e carboxila, de modo semelhante ao que ocorre com aminoácidos. Para cada estado de protonação, realizamos cálculos de otimização de geometria e verificação de mínima energia com a teoria DFT utilizando diferentes funcionais e conjuntos de bases para orbitais atômicos. Partindo das geometrias de menor energia, com a teoria TD-DFT (B3LYP/311++G(d,p)) fizemos cálculos das transições eletrônicas. A melhor concordância com os resultados experimentais foi obtida com a molécula na forma aniônica. Na comparação dos resultados da posição espectral da transição de mais baixa energia, no processo de absorção ótica, observamos uma diferença relativa de 0,6%. Para a fluorescência otimizamos e verificamos a geometria do estado excitado e obtivemos as energias de transição vertical com o método TD-DFT (B3LYP/Def2-TZVP) com o qual tivemos um resultado de lambda = 407nm considerado satisfatório quando comparado com o valor experimental lambda= 394nm. Nas formas neutra e catiônica, as diferenças relativas entre os cálculos e os experimentos foram maiores, chegando a 11% na posição da banda de fluorescência da molécula neutra. Usando simulações de Dinâmica Molecular conseguimos estimar quantas moléculas de água se distribuem em torno do o-Abz. Os resultados mostram que, embora exista um número parecido de moléculas de água solvatando a molécula nas formas aniônica e catiônica, há uma redução na quantidade de ligações de hidrogênio realizadas pela protonação catiônica em relação à aniônica. O modelo utilizado para simular o o-Abz-NH(CH3) em micelas de SDS apresentou resultados satisfatórios com erro relativo entre 0,7\\% e 0,9%, no entanto são necessárias outras abordagens computacionais e experimentais para indicar em qual região a molécula se encontra na micela, dando assim mais confiabilidade e uma melhor interpretação aos resultados. / The ortho-aminobenzoic acid is a molecule largely employed as a fluorescent probe in peptide and membrane studies. The solvent dependence of its spectroscopic properties deserves great interest and we describe here results of experimental measurements and computational calculations by \\textit and Molecular Dynamics methods about spectroscopic and solvation properties of the molecule in aqueous medium at different pH values. We also examined the derivative 2-amino-N-methyl-benzamide (o-Abz-NHCH3), investigating the spectral modifications in its interaction with SDS micelles. The results of titration experiments could be interpreted as originated from three protonation states for o-Abz: in neutral pH and above, both carboxy and amine groups are deprotonated, and the molecule is in the anionic form. Decreasing the pH, protonation of amino group or carboxy renders the molecule neutral (pK = 5.0) and at low pH both groups are protonated and the molecule is in the cationic form (pK = 2.3). Geometry optimization and determination of energy minima were performed with the molecule in each protonation state using Density Functional Theory (DFT) with different functionals and basis set for atomic orbitals. Eletronic transitions were calculated from lowest energy geometry using TD-DFT (B3LYP/311++G(d,p)). The best agreement with experimental results were obtained for the anionic molecule: we observed a relative difference of 0.6\\% for the lowest energy optical transition. From the optimized geometry of the excited state the vertical transition was calculated with TD-DFT (B3LYP/Def2-TZVP), and the emission was predicted to occur at 407nm, a reasonable result compared with the experimental value or 394nm. For the molecule in neutral or cationic state, the relative differences between experimental and calculation results were greater, amounting to 11\\% for the fluorescence band in the neutral species. From Molecular Dynamics simulation we estimated the number of water molecules distributed aroud the o-Abz molecule. The results show that, although there is similar number of water molecules solvating the o-Abz in anionic and cationic state, there is a decrease in the amount of hydrogen bond in the cationic molecule. The simulation of the derivative o-Abz-NHCH3 in SDS micelles by implicit solvent methods gave results comparable to the experimental ones, with relative deviations lower than 1\\%. It should be noted that further study should be carried out in order to have a better knowledge about the location of the probe in the micelle, and to afford a beter interpretation of the results.
62

Liberation of the Ecclesia : The Unfinished Project of Liturgical Theology

Hjälm, Michael January 2011 (has links)
This dissertation is a critical study of the paradigm of Liturgical Theology. Focus in this systematic inquiry has been on the Russian school with the focal point in the works of Alexander Schmemann, who was active in the late 20th century. The main question of the thesis concerns the relation between theory and practice in Liturgical Theology.                       It is claimed that the relation between theory and practice corresponds to the relation between ritual action and communicative action. The former concerns the identity founded on the unavoidable alterity immanent in life, but also transcending life through a holistic encounter with life, which enables us to express a holistic attitude to life and the entire world. The latter concerns the equally unavoidable rationalization of life which gives rise to a continuous atomization of life through science and the process of acquiring facts and data.                       The thesis makes use of different theories for the reaching of an explanatory theory in connection to theory and practice. Foremost the Theory of Communicative Action in the works of Jürgen Habermas and the re-interpretation of disclosure by Nikolas Kompridis is used. It is claimed tthat ritual action is connected to a primary disclosure attached to otherness with the intention of revealing the identity of the Ecclesia. Without identity, we are left with a never-ending debate and a continuous atomization where every answer exponentially provokes more questions. Communicative action then is connected with a secondary co-disclosure with the intention for the reaching of mutual understanding, making subjects accountable and responsible. Without communicative action we are bound on a long walk into the never ending sea of being. The missionary imperative in the Ecclesia is dependent on the co-existence of ritual action and communicative action.
63

Reaction Between Grignard reagents and Heterocyclic N-oxides : Synthesis of Substituted Pyridines, Piperidines and Piperazines

Andersson, Hans January 2009 (has links)
This thesis describes the development of new synthetic methodologies for preparation of bioactive interesting compounds, e.g. substituted pyridines, piperidines or piparazines. Thesecompounds are synthesized from commercially available, cheap and easily prepared reagents, videlicet the reaction between Grignard reagents and heterocyclic N-oxides.  The first part of this thesis deals with an improvement for synthesis of dienal-oximes and substituted pyridines. This was accomplished by a rapid addition of Grignard reagents to pyridine N-oxides at rt. yielding a diverse set of substituted dienal-oximes. During these studies, it was observed that the obtained dienal-oxmies are prone to ring-close upon heating. By taking advantage of this, a practical synthesis of substituted pyridines was developed. In the second part, an ortho-metalation of pyridine N-oxides using Grignard reagents is discussed. The method can be used for incorporation of a range of different electrophiles, including aldehydes, ketones and halogens. Furthermore, the importance for incorporation of halogens are exemplified through a Suzuki–Miyaura coupling reaction of 2-iodo pyridine N-oxides and different boronic acids. Later it was discovered that if the reaction temperature is kept below -20 °C, the undesired ringopening can be avoided. Thus, the synthesis of 2,3-dihydropyridine N-oxide, by reacting Grignard reagents with pyridine N-oxides at -40 °C followed by sequential addition of aldehyde or ketone, was accomplished. The reaction provides complete regio- and stereoselectivity yielding trans-2,3-dihydropyridine N-oxides in good yields. These intermediate products could then be used for synthesis of either substituted piperidines, by reduction, or reacted in a Diels–Alder cycloaddtion to give the aza-bicyclo compound. In the last part of this thesis, the discovered reactivity for pyridine N-oxides, is applied on pyrazine N-oxides in effort to synthesize substituted piperazines. These substances are obtained by the reaction of Grignard reagents and pyrazine N-oxides at -78 °C followed by reduction and protection, using a one-pot procedure. The product, a protected piperazine, that easily can be orthogonally deprotected, allowing synthetic modifications at either nitrogens in a fast and step efficient manner. Finally, an enantioselective procedure using a combination of PhMgCl and (-)-sparteine is discussed, giving opportunity for a stereoselective synthesis of substituted piperazines.
64

A Convenient Synthesis of Pyrrolnitrin and Related Halogenated Phenylpyrroles

MORRISON, MATTHEW 07 October 2009 (has links)
This thesis details a straightforward synthetic route to the antifungal compound pyrrolnitrin 1.2, along with several analogous halogenated phenylpyrroles. The proposed synthetic protocol involved the Suzuki-Miyaura cross-coupling of appropriately halogenated pyrrole pinacolboronate esters and aryl compounds. In the efforts towards preparing the cross-coupling partners, we report a regiospecific and high yielding synthesis of a 3-chloro pyrrole compound 2.14, its brominated analog 2.16, an iodinated analog 2.17, and the corresponding pinacolboronate ester 2.18. We also report a generalized reaction sequence (lithiation/carboxylation/Schmidt reaction/oxidation) for the preparation of halogenated benzoic acids, anilines and nitrobenzenes. In particular, we synthesized the desired halogenated nitrobenzene coupling partner 3.27 in excellent yield. We were also able to show that the conditions employed in this sequence were mild enough to allow preparation of the 2-bromo-6-iodo compound 3.33. Once the coupling partners were prepared, we developed the optimal conditions for our Suzuki-Miyaura cross-coupling reactions. In doing so, we were able to prepare our target compound 1.2 and several halogenated analogs in good yields. We also prepared brominated and deuterated arylpyrroles 4.27 and 4.28, respectively, for future use in mechanistic studies of the pyrrolnitrin biosynthetic enzymes, PrnB, Prn C and PrnD. This required preparation of the corresponding brominated and deuterated pyrrole pinacolboronate esters 4.24 and 4.26. / Thesis (Master, Chemistry) -- Queen's University, 2009-09-29 13:58:35.186
65

Méthodologies d'accès à des N-hydroxyphtalimides hautement substitués, vers de nouveaux catalyseurs d'oxydation aérobie

Michaux, Jerome 09 November 2012 (has links) (PDF)
Dans un contexte industriel où les réactions d'oxydation sont réalisées dans des conditions qui ne satisfont pas toujours les principes de la chimie verte, notre groupe étudie des catalyseurs de structure N-hydroxyphtalimide (NHPI), pour l'oxydation aérobie de substrats organiques variés dans des conditions douces. Dans le but d'obtenir des catalyseurs plus actifs, deux familles d'analogues hautement substitués sur le noyau phtalimide ont été préparées, suivant deux nouvelles méthodologies de synthèse. La première consiste en la bis-ortho-métallation / silylation d'acides ortho-phtaliques non protégés, pour un accès très rapide à des analogues silylés du NHPI. Les premiers tests en catalyse d'oxydation aérobie montrent une influence intéressante des groupements silyles sur la stabilité de l'espèce active, via leur encombrement stérique, cela permettant une amélioration de l'activité catalytique. La seconde stratégie inclut une cyclotrimérisation [2+2+2] totalement intramoléculaire d'ène-diyne diesters, pour la construction d'un squelette bis-ortho-lactone pentacyclique innovant. Ces intermédiaires sont aisément transformés en 3,6-bis(2-hydroxyphényl)-4,5-diarylphtalimides, ces composés présentant une symétrie C2 et deux axes d'atropoisomérie. Le dédoublement des énantiomères a été effectué, dans la perspective d'obtenir des catalyseurs d'oxydation aérobie potentiellement énantiosélectifs.
66

Cálcio e fósforo para juvenis da tilápia-do-nilo / Calcium and phosphorus for Nile tilapia juvenile

Rocha, Mariucha Karina Honório Ribeiro [UNESP] 11 January 2016 (has links)
Submitted by MARIUCHA KARINA HONORIO RIBEIRO ROCHA null (mariucha_rocha@yahoo.com.br) on 2016-01-28T17:44:50Z No. of bitstreams: 1 Tese_Mariucha.pdf: 690234 bytes, checksum: 3773a7548f01be7edc3ab559700c7133 (MD5) / Rejected by Sandra Manzano de Almeida (smanzano@marilia.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo as orientações abaixo: O número de páginas indicado na ficha catalográfica é diferente do número de páginas do arquivo PDF. Por favor, submeta o PDF completo no Repositório. Caso queira disponibilizar apenas o conteúdo parcial, durante a submissão indique na opção “Versão a ser disponibilizada online imediatamente” e informe o tempo para disponibilização do conteúdo integral. Ao submeter o arquivo completo a Coordenadoria Geral de Bibliotecas se encarregará de disponibilizar apenas o conteúdo parcial que segundo a Portaria UNESP 396 de 10 de setembro de 2015 consiste em: Artigo 3º V - conteúdo parcial: as páginas pré-textuais (a folha de rosto, a dedicatória, os agradecimentos, a epígrafe, o resumo na língua vernácula, o resumo em língua estrangeira, as listas de ilustrações, de tabelas, de abreviaturas, de siglas e de símbolos e o sumário), a introdução, a conclusão ou as considerações finais e as referências do trabalho. Agradecemos a compreensão. on 2016-01-29T18:13:27Z (GMT) / Submitted by MARIUCHA KARINA HONORIO RIBEIRO ROCHA null (mariucha_rocha@yahoo.com.br) on 2016-05-11T16:02:08Z No. of bitstreams: 1 Tese_Mariucha.pdf: 690234 bytes, checksum: 3773a7548f01be7edc3ab559700c7133 (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-05-12T19:00:10Z (GMT) No. of bitstreams: 1 rocha_mkhr_dr_bot.pdf: 690234 bytes, checksum: 3773a7548f01be7edc3ab559700c7133 (MD5) / Made available in DSpace on 2016-05-12T19:00:10Z (GMT). No. of bitstreams: 1 rocha_mkhr_dr_bot.pdf: 690234 bytes, checksum: 3773a7548f01be7edc3ab559700c7133 (MD5) Previous issue date: 2016-01-11 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Neste estudo foram utilizados 330 juvenis da tilápia-do-nilo (peso inicial 15,26±0,3g) alimentados com dieta ausente de suplementação e suplementadas com 3,4:5,1; 5,1:5,1; 6,7:10,0 e 10,0:10,0g kg-1 de cálcio e fósforo, durante 96 dias. Peixes alimentados com 5,1: 5,1g kg-1 apresentaram peso final e ganho de peso menor (P<0,05) comparados aos com 6,7:10,0 e 10,0:10,0g Kg-1. A conversão alimentar de peixes alimentados com dieta suplementada foi melhor (P<0,05) comparada aos alimentados com dieta não suplementada. A análise morfométrica da vértebra dos peixes mostrou aumento (P<0,05) em animais alimentados com 6,7:10,0g Kg-1. O teor de cálcio e fósforo corporal de peixes alimentados com 6,7:10,0g kg-1 foi maior comparado aos alimentados com 5,1:5,1g kg-1. O teor de cinzas nas vértebras de peixes alimentados com dietas suplementadas foi maior (P>0,05) comparada aos sem suplementação. O teor de cálcio na vértebra dos peixes alimentados com dieta contendo 10,0:10,0g kg-1 foi maior (P<0,05) comparado às demais.O teor de cálcio na vértebra dos peixes alimentados com dietas contendo 6,7:10,0 e 5,1:5,1g kg-1 foi maior (P<0,05) comparado aos alimentados com 3,4:5,1g kg-1. Os teores de fósforo na vértebra de peixes alimentados com dietas de 3,4: 5,1g kg-1 e 6,7:10,0g kg-1 foram menores (P<0,05) comparados aos peixes alimentados com as demais dietas. As dietas 6,7:10,0 e 10,0:10,0g kg-1 de cálcio e fósforo atenderam as necessidades dos Juvenís da tilápia-do-nilo em desempenho e mineralização óssea. / This study used 330 juveniles of Nile tilapia (initial weight 15.26 ± 0.3g) fed unsuplemented diet and supplemented with 3.4: 5.1; 5.1: 5.1; 6.7:10.0 and 10.0:10.0g kg-1 of calcium and phosphorus for 96 days. Fish fed with 5.1: 5.1g kg-1 final weight and had lower weight gain (P <0.05) compared to those with 6.7: 10.0 and 10.0:10.0g kg-1. The feed of fish fed with diet supplemented was better (P <0.05) compared to the unsupplemented diet fed. The morphometric analysis of the vertebra showed fish increase (P <0.05) in animals fed with 6.7: 10.0 g kg-1. The body calcium and phosphorus fish fed with 6.7:10.0 g kg-1 was higher compared to fed 5.1: 5.1g kg-1. The ash content in fish fed diets supplemented vertebrae was higher (P> 0.05) compared to no supplementation. The calcium content in fish vertebrae fed a diet containing 10.0: 10.0 g kg-1 was higher (P <0.05) compared to too much trouble calcium content in the vertebrae of fish fed diets containing 6,7 : 10.0 and 5.1: 5.1g kg-1 was higher (P <0.05) compared to fed 3.4: 5.1g kg-1. The phosphorus content in the vertebra fish fed diets with 3.4: 5,1g kg-1 and 6.7: 10.0 g kg-1 were lower (P <0.05) compared to fish fed with the other diets. Diets 6.7:10.0;10.0:10.0g kg-1 of calcium and phosphorus met the needs of juveniles of Nile tilapia in performance and bone mineralization. / CNPq: 140304/2013-4
67

O orto-eugenol apresenta atividade antinociceptiva e anti-inflamatória em camundongos

Fonseca, Diogo Vilar da 14 March 2016 (has links)
Submitted by Maike Costa (maiksebas@gmail.com) on 2017-02-02T13:27:46Z No. of bitstreams: 1 arquivo total.pdf: 2209770 bytes, checksum: f1ff3ca285ff26a080821defd683aad9 (MD5) / Made available in DSpace on 2017-02-02T13:27:46Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 2209770 bytes, checksum: f1ff3ca285ff26a080821defd683aad9 (MD5) Previous issue date: 2016-03-14 / Eugenol's ability to reduce nociception and act in the inflammatory process has gained great prominence in the scientific community, emerging interest in researching the ortho-eugenol also has these same activities. Researching ortho-eugenol’s antinociceptive and anti-inflammatory activity, and its possible mechanisms of action is therefore of interest. The administration of vehicle, ortho-eugenol (50, 75 and 100 mg/kg i.p), morphine (10 mg/kg, i.p) or dexamethasone (2 mg/kg, s.c) occurred thirty minutes before the completion of pharmacological tests. The experiments started with psychopharmacological screening and determination of the LD50. The effect of ortho-eugenol on motor coordination in mice was investigated in the rota-rod test. The antinociceptive activity was assessed using chemical tests (test of writhing induced by acetic acid, formalin, test and glutamate) and thermal (hot plate test). To study the role of the adrenergic system, was administered α2-adrenergic antagonist, yohimbine, fifteen minutes before the ortho-eugenol injection the test of writhing induced by acetic acid. The test vascular permeability induced by acetic acid and peritonitis test were used to assess the anti-inflammatory effects of ortho-eugenol in mice. In the test of peritonitis, the levels of pro-inflammatory cytokines and phosphorylated forms of NF-kB and p38 were analyzed in peritoneal fluid. In the behavioral pharmacological screening, the different doses tested ortho-eugenol (200, 225, 250, 300 e 400 mg/kg, i.p.)psicodepressoras showed behavioral changes such as decreased ambulation, and especially analgesia. The LD50 was 307.5 mg / kg, with a confidence interval between 212.1 and 446.0 mg / kg body weight for male and female mice. Pretreatment with ortho-eugenol did not change Rota-rod test coordination test results, but reduced the number of writhes and licking times in the glutamate assay. The reaction time from thermal stimulus was significantly increased in the hot plate test after administration of ortho-eugenol. Treatment with yohimbine reversed the antinociceptive effect of ortho-eugenol, suggesting involvement of the adrenergic system. In anti-inflammatory tests, ortho-eugenol inhibited acetic acid induced vascular permeability and leukocyte migration, reducing TNF-α and IL-1β by virtue of its suppression of NF-kB and p38 phosphorylated forms in the peritonitis test. From these results, ortho-eugenol antinociceptive effects mediated by the adrenergic system and anti-inflammatory activity through regulation of proinflammatory cytokines and phosphorylation of NF-kB and p38 become evident for the first time. / A capacidade do eugenol em reduzir a nocicepção e agir no processo inflamatório tem ganhado grande destaque na comunidade cientifica, surgindo o interesse em pesquisar se o orto-eugenol também possui essas mesmas atividades. Diante disso, surgiu interesse em pesquisar a atividade antinociceptiva e anti-inflamatória do orto-eugenol e seus possíveis mecanismos de ação. A administração do veículo (Tween 80 mais água destilada), orto-eugenol (50, 75 e 100 mg/kg, i.p.), morfina (10 mg/kg, i.p.) ou dexametasona (2 mg/kg, s.c.) aconteceram trinta minutos antes da realização dos testes farmacológicos. Os experimentos iniciaram com a triagem psicofarmacológica e determinação da DL50. O efeito do orto-eugenol sobre a coordenação motora de camundongos foi investigada no teste do Rota-rod. A atividade antinociceptiva foi avaliada utilizando testes químicos (teste das contorções abdominais induzidas pelo ácido acético, teste da formalina e teste do glutamato) e térmico (teste da placa quente). Para estudar a participação do sistema adrenérgico, administrou-se o antagonista adrenérgico α2, ioimbina, quinze minutos antes da injeção do orto-eugenol no teste das contorções induzidas pelo ácido acético. O teste da permeabilidade vascular induzida pelo ácido acético e o teste da peritonite foram utilizados para avaliar o efeito anti-inflamatório do orto-eugenol em camundongos. No teste da peritonite, os níveis de citocinas pró-inflamatórias e as formas fosforiladas de NF-κB e de p38 foram analisados no líquido peritoneal. Na triagem farmacológica comportamental, as diferentes doses testadas do orto-eugenol (200, 225, 250, 300 e 400 mg/kg, i.p.) apresentaram alterações comportamentais psicodepressoras, tais como ambulação diminuída e, principalmente, analgesia. A DL50 foi de 307,5 mg/kg, com intervalo de confiança entre 212,1 e 446,0 mg/kg de peso corporal para camundongos machos e fêmeas. O pré-tratamento com o orto-eugenol não alterou a coordenação motora no teste do Rota-rod, mas reduziu o número de contorções abdominais, o tempo de lambida no teste do glutamato e ambas as fases do teste da formalina. O tempo de reação ao estímulo térmico foi significativamente aumentando no teste da placa quente, após a administração do orto-eugenol. O tratamento com a ioimbina reverteu o efeito antinociceptivo do orto-eugenol, sugerindo ativação do sistema adrenérgico. Nos testes anti-inflamatórios, o orto-eugenol inibiu o aumento da permeabilidade vascular induzida por ácido acético e a migração de leucócitos via redução dos níveis de TNF-α e IL-1β em virtude da supressão das formas fosforiladas de NF-κB e p38 no teste da peritonite. Diante desses resultados, torna-se evidente, pela primeira vez o efeito antinociceptivo mediado pelo receptor adrenérgico α2 e atividade anti-inflamatória por meio da regulação de citocinas pró-inflamatórias e fosforilação de NF-κB e p38.
68

Analysis and Design of Surface Micromachined Micromanipulators for Out-of-Plane Micropositioning

Jensen, Kimberly A. 23 July 2003 (has links) (PDF)
This thesis introduces two ortho-planar MEMS devices that can be used to position microcomponents: the XZ Micropositioning Mechanism and the XYZ Micromanipulator. The displacement and force relationships are presented. The devices were fabricated using surface micromachining processes and the resulting mechanisms were tested. A compliant XYZ Micromanipulator was also designed to reduce backlash and binding. In addition, several other MEMS positioners were fabricated and tested: the Micropositioning Platform Mechanism (MPM), the Ortho-planar Twisting Micromechanism (OTM), and the Ortho-planar Spring Micromechanism (OSM).
69

Fundamental Components for Lamina Emergent Mechanisms

Jacobsen, Joseph O. 22 February 2008 (has links) (PDF)
This thesis introduces lamina emergent mechanisms (LEMs) and presents components that can be used as building blocks to create LEMs capable of more complex motion. As the name suggests, lamina emergent mechanisms are fabricated out of planar materials (the lamina) but their motion is out of that plane (emergent). Lamina emergent mechanisms can provide benefits that include reduced manufacturing costs and minimal volume when in the planar state. The compact initial state of LEMs is beneficial in reducing shipping costs, especially in volume critical applications. LEMs also exhibit the potential benefits of compliant mechanisms, namely increased precision, reduced weight, reduced wear, and part count reduction. The LEM components presented in this thesis include flexible segments, fundamental mechanisms, and a new complaint joint, the lamina emergent torsional (LET) Joint. The flexible segments are developed through changes in geometry, boundary/loading conditions, and material. The fundamental mechanisms presented have motion similar to planar change-point four-bar and six-bar mechanisms, and spherical change-point mechanisms. The LET Joint is presented as a compliant joint suited for applications where large angular rotation is desired, but high off-axis stiffness is not as critical. The joint is introduced and the equations necessary for determining the force-deflection characteristics and stress are presented. Since the LET Joint can be fabricated from a single planar layer, it is well suited for macro and micro applications. Illustrative examples of the LET Joint are provided with devices fabricated from materials as diverse as steel, polypropylene, and polycrystalline silicon.
70

EXPLORATION OF THORIUM HYDROTRIS(PYRAZOLYL)BORATE COMPLEXES TO ACCESS RARE MULTIPLE BONDS

Courtney Joy Newberry (14209631) 02 December 2022 (has links)
<p>  </p> <p>Actinide complexes have been targeted for their potential in group transfer applications. The study of these metals, such as thorium and uranium, is essential to better understand the reactions these metals are capable of facilitating.  Hydrotris(pyrazolyl)borates such as hydrotris(3,5-dimethylpyrazolyl)-borate (Tp*) and hydrotris(pyrazolyl)-borate (Tp) are superbulky, scorpionate ligands that have previously been used to synthesize novel uranium complexes and probe the reactivity of these materials. Similar thorium analogs have also been synthesized, but their reactivity has yet to be explored in great depth. Tp*ThCl3(THF) and Tp2ThCl2 have been reproduced and investigated as possible starting materials for such reactivity studies. While the former was found to be largely unreactive, the latter presents promising reactivity for the synthesis of thorium-element multiple bonds, and a novel thorium imido, Tp2Th(NDipp)(THF), has been synthesized and characterized using this scaffold. </p> <p><br></p> <p>The reactivity of a uranium tetrakis(imido), [U(NDipp)4][K2], has also been investigated to probe the prospect of group transfer reactions for potential catalysis applications in the future. An isocyanate, PhNCO, was reacted with this compound; the observed product showed that group transfer was incomplete, and a four-membered metallocycle product is likely formed instead. The synthesis of a novel thorium tris(imido) has also been targeted, and preliminary results are outlined. </p>

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