Les énergies typiques de l’interaction dipolaire entre atomes de Rydberg sont plusieurs ordres de grandeur au-dessus des énergies d’interaction d’atomes et molécules dans le niveau fondamental. Une échelle de distance de plusieurs micromètres découle de cette interaction, ce qui est à l’origine du phénomène de blocage dipolaire, ou la suppression d’excitations d’atomes de Rydberg dans des nuages atomiques denses. Dans une première partie de cette thèse, nous étudions l’application de ce phénomène à l’excitation déterministe d’un atome unique à partir d’un condensat de Bose-Einstein piégé magnétiquement devant une puce à atomes. Une deuxième partie est consacrée à l’étude de l’interaction dipolaire d’ensembles denses d’atomes de Rydberg par spectroscopie microonde des transitions vers les niveaux de Rydberg proches en énergie. Ces ensembles sont créés par excitation laser à partir d’un nuage froid d’atomes de Rb87 dans l’état fondamental. Les spectres des transitions microonde sont élargis et déplacés par l’interaction dipolaire. L’étude de ces spectres permet ainsi d’inférer plusieurs aspects de la distribution spatiale des atomes de Rydberg créés, ce qui révèle différents processus d’excitation selon que la lumière laser est à résonance ou désaccordée. L’évolution mécanique du nuage d’atomes de Rydberg en fonction de leur interaction répulsive a aussi été observée, grâce à une série de spectres microonde à différents délais de l’excitation. Nous montrons ainsi que, pour des échelles temporelles supérieures à 10µs, leur mouvement doit être pris en compte pour la compréhension de la dynamique d’excitation de Rydberg dans des nuages atomiques denses. / The typical energy scales that arise from dipolar interaction between Rydberg atoms are orders of magnitude bigger than those related to the interaction between atoms and molecules at the ground level. A length scale of several micrometres stems from that strong interaction, which is the cause of the so-called dipole blockade effect, or the suppression of excitation of Rydberg atoms within dense atomic clouds. In the first part of this thesis, we study the possibility of using this effect to the deterministic excitation of a single atom within a Bose-Einstein condensate in a magnetic trap created on an atom chip. In a second part, we study the dipolar interaction of Rydberg atoms in dense ensembles, through microwave spectroscopy of transitions between Rydberg levels close in energy. These ensembles are created by laser excitation of Rb87 atoms initially in the ground level, trapped in a dense, cold cloud. The spectra of the microwave transitions are broadened and shifted, due to dipolar interaction. The study of these spectra then allows to infer several aspects of the spatial distribution of the Rydberg atoms, which reveals different excitation processes depending whether the laser light is in resonance or shifted with respect to the Rydberg transition. The mechanical evolution of the Rydberg atom cloud as a function of their mutual repulsive interaction was also observed, by performing microwave spectroscopy at different delays from the laser excitation. By these observations we show that, for time scales bigger than 10µs, their movement must be taken into account if one wants to understand the dynamics of the Rydberg excitation in dense atomic clouds.

Kainic acid has been used for nearly 50 years as a tool in neuroscience due to its pronounced neuroexcitatory properties. However, the significant price increase of kainic acid resulting from the disruption in the supply from its natural source, the alga Digenea Simplex, as well as inefficient synthesis of kainic acid, call for the exploration of functional mimics of kainic acid that can be synthesized in a simpler way. Aza kainoids analog could be one of them. The unsubstituted aza analog of kainoids has demonstrates its ability as an ionotropic glutamate receptor agonist and showed affinity in the chloride dependent glutamate (GluCl) binding site. This opened a question of the importance of the presence of one nitrogen or both nitrogens in the aza kainoid analogs for binding to glutamate receptors. Therefore, two different pyrrolidine analogs of kainic acid, trans-4-(carboxymethyl)pyrrolidine-3-carboxylic acid and trans-2-carboxy-3-pyrrolidineacetic acid, were synthesized through multi-step sequences. The lack of the affinity of both pyrrolidine analogs in GluCl binding site indicated that both nitrogens in aza kainoid analogs are involved in hydrogen bonding with receptors, significantly enhancing their affinity in GluCl binding site. Another potential functional mimic of kainic acid is isoxazolidine analogs of kainoids whose skeleton can be constituted directly via a 1, 3 dipolar cycloaddition as the key step. The difficulty in synthesizing N-unsubstituted isoxazolidines when applying such common protecting groups as alkyl, phenyl and benzyl groups, and the requirement of a desired enantioselectivity due to the three chiral ceneters in kainic acid, pose great challenges. Hence, several different protected nitrones were studied to establish that diphenylmethine nitrone may be a good candidate as the dipole in that the generated isoxazolidines can be deprotected in mild conditions with high yields. Our investigations also indicated that the exo/endo selectivity of the 1, 3 dipolar cycloaddition can be controlled by Lewis acids, and that the application of a directing group in dipolarophiles can accomplish a satisfied enantioselectivity. Those results demonstrated the synthesis of isoxazoldines analogs of kainic acid is very promising.

Orientadores: Fanny Béron, Kleber Roberto Pirota / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-30T20:53:23Z (GMT). No. of bitstreams: 1 Velo_MuriloFerreira_M.pdf: 6384347 bytes, checksum: 64859a7498ff2d02184a4fff9787d436 (MD5) Previous issue date: 2016 / Resumo: Interações dipolares são amplamente estudadas em magnetismo, devido ao fato de que elas têm um papel fundamental na maioria dos sistemas magnéticos. Porém, para vários sistemas, o cálculo das interações magnetostáticas é feito de duas maneiras: considerando-se apenas o primeiro termo da expansão multipolar e/ou aproximando as entidades magnéticas por dipolos perfeitos. Neste trabalho iremos realizar este cálculo de maneira exata, através da expansão multipolar, considerando a forma geométrica da entidade magnética. Para tal montamos um sistema macroscópico bidimensional composto por agulhas magnéticas de bússola, no qual foi automatizado a aquisição de imagens e o controle de campo magnético. No objetivo de verificar a exatidão do nosso cálculo, implementamos uma simulação utilizando o método de Monte Carlo para comparar com os resultados experimentais. Focamos o estudo sobre sistemas de duas e cinco agulhas, sendo que o primeiro permite a comparação com a solução analítica exata do problema. Observamos que a introdução dos termos de ordem mais alta na expansão multipolar modifica o potencial magnético gerado por uma agulha de bússola. A expansão multipolar do potencial mostrou que devemos considerar termos de ordem l = 1, 3 e 5, sendo que os termos de ordem par são nulos e termos l ? 7 são desprezíveis. A simulação de Monte Carlo reproduziu com fidelidade o comportamento dos sistemas experimentais, mostrando uma boa concordância entre as curvas de histerese simuladas e experimentais. Explicamos os resultados a partir do fato que a expansão multipolar introduz mínimos locais nos diagramas de energia de interação de duas partículas com campo magnético aplicado nulo. Estas regiões são conhecidas como os pontos de equilíbrio metaestáveis de um sistema magnético. Para um sistema de duas agulhas, descrevemos como os saltos na curva de histerese estão relacionados com descontinuidades na trajetória no espaço de fases de energia do sistema, criadas pelos termos de ordem mais alta. Dos nossos resultados, concluímos que para descrevermos o comportamento magnético de um sistema de agulhas de bússola, devemos levar em conta termos de ordem mais alta na expansão multipolar, bem como a geometria desta entidade / Abstract: Dipolar interactions are widely studied in magnetism, since they play a key role in most magnetic systems. However, for several systems the magnetostatic interactions calculation is done through two ways: considering only the multipole expansion first term and/or approximating the magnetic entities as perfect dipoles. In this work we will perform this calculation exactly, through the multipole expansion, considering the magnetic entities geometric shape. For such, we set up a two-dimensional macroscopic system made of magnetic compass needles, where we automated the image acquisition and the magnetic field control. In the objective of verifying our calculation accuracy, we implemented a simulation using the Monte Carlo¿s method to compare with the experimental results. We focused the study on systems of two and five needles, since the first one allowing comparing with the experimental results. We observed that the introduction of higher order terms in the multipole expansion modifies the magnetic potential generated by a compass needle. The multipole expansion showed that we need to consider order terms of l = 1, 3 and 5, with nulls even terms are and terms of l ? 7 are negligible. The Monte Carlo simulation accurately reproduced the experimental systems behaviors, exhibiting a good agreement between the simulated and experimental hysteresis curves. We explained the results through the fact that the multipole expansion introduces local minima in the two magnetic particles interaction energy diagrams with null applied magnetic field. These regions are known as metastable equilibrium points in a magnetic system. For a two-needle system, we described in detail how the hysteresis curve drops are related to trajectory discontinuities in the system energy phase space, created by the higher order terms. From our results, we conclude that to describe the magnetic behavior of a compass needle system, one must take into account higher order terms in the multipole expansion, as well as the entity geometry / Mestrado / Física / Mestre em Física / 1374983/2014 / CAPES

Orientador: Marcelo Knobel / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Física Gleb Wataghin / Made available in DSpace on 2018-08-30T18:13:51Z (GMT). No. of bitstreams: 1 OrozcoHenao_JuanManuel_M.pdf: 7687296 bytes, checksum: d9aecf2d118aed0c43ab747d0dcff34c (MD5) Previous issue date: 2016 / Resumo: Nanopartículas de magnetita com diâmetros entre 5nm e 19nm sintetizadas mediante um método de decomposição térmica são apresentadas. A caracterização estrutural é feita usando diferentes técnicas experimentais como a microscopia eletrônica de transmissão (TEM), difração de raios-X e espalhamento de raios-X a baixos ângulos (SAXS) de onde são obtidos os tamanhos e a forma das nanopartículas. As propriedades magnéticas e de magneto-hipertermia das nanopartículas são estudadas para diferentes parâmetros de produção como concentração dos surfactantes, temperaturas de refluxo e atmostfera de crescimento. A dependência com a temperatura das propriedades magnéticas são analisadas dentro do marco do modelo usual do superparamagnetismo e o modelo de interação superparamagnética (ISP), de onde os parâmetros magnéticos dependentes do tamanho como anisotropia magnética (1.06x10^4 J/m^3 até 9.91x10^4 J/m^3), momento magnético por partícula (2618?B até 11500?B), temperatura de bloqueio (18K até mais de 300K) e energia de ineração dipolar magnética (0.55x10^-21 J até 5.5x10^-21 J) são inferidos. Os resultados de magneto-hipertermia foram obtidos mediante a medição da resposta térmica das nanopartículas de magnetita suspendidas em tolueno. Valores da taxa de absorção específica (SAR) são calculados experimental e teoricamente utilizando a teoria de resposta linear para um sistema superparamagnético não interagente. Valores de SAR entre 3.0W/g e 40.3W/g e a sua dependência com a frequência e o campo aplicado são apresentados. Como resultado interessante, a resposta de magneto-hipertermia para as nanopartículas de 19nm preparadas na presença de oxigênio e mais de 10 vezes maior do que nanopartículas similares mas obtidas na ausência da atmosfera de oxigênio. Também é destacada a possibilidade de prever a resposta de magneto-hipertermia num sistema de nanopartículas magnéticas mediante a obtenção dos parâmetros de caracterização magnetica e estrutural / Abstract: Magnetite nanoparticles with diameters between 5nm and 19nm synthesized by means of a thermal decomposition method are presented. Structural characterization is made by different experimental techniques such as transmission electron microscopy (TEM), X-ray diffraction and Small Angle X-ray Scattering (SAXS) from where nanoparticles size and shape are obtained. Magnetic and magneto-hyperthermia properties of the nanoparticles are studied for different production parameters, such as surfactant concentrations, refluxing temperature and growth atmosphere. Temperature dependence of the magnetic properties are analyzed in the framework of the standard superparamagnetism model and the interacting superparamagnetic model (ISP), from where size dependent magnetic parameters for each sample such as anisotropy (1.06×10^4 J/m^3 to 9.91x10^4 J/m^3) magnetic moment per particle (2618?B to 11500?B), blocking temperature (18K to above 300K) and magnetic dipolar interaction energy on dried nanoparticle samples (0.55 × 10^?21 J to 5.5 × 10^?21 J) are inferred. Magneto-hyperthermia results are obtained by measuring the thermal response of magnetite nanoparticles dissolved in toluene. Specific absorption rate (SAR) values are theoretically and experimentally calculated by means of a linear response theory approach of a non-interacting superparamagnetic system. SAR values between 5.8W/g and 40.3W/g are reported; interestingly, the magneto-hyperthermia response for 19nm nanoparticles prepared in presence of an oxygen atmosphere is more than 10 times larger than similar particles obtained in absence of oxygen atmosphere. Also it is important to highlight the possibility to obtain the magneto-hyperthermia behavior of a magnetic nanoparticles system by knowing a priori its structural and magnetic characterization parameters / Mestrado / Física / Mestre em Física / 1247647/2013 / CAPES

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23460号 / 理博第4754号 / 新制||理||1681(附属図書館) / 京都大学大学院理学研究科生物科学専攻 / (主査)教授 杤尾 豪人, 教授 森 和俊, 教授 望月 敦史 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

En esta tesis doctoral se ha estudiado los iluros de azometino generados in situ en reacciones de cicloadición 1,3-dipolar y diferentes dipolarófilos para la síntesis multicomponente (libre de metales) de derivados de indolizidina a partir de pipecolinatos, aldehídos y dipolarofilos de forma térmica, y también a partir de ácido pipecólico de forma descarboxilada. También se ha estudiado la reacción de cicloadición 1,3-dipolar térmica multicomponente entre iluros de azometino no activados generados in situ a partir de aminas, aldehídos aromáticos y alquenos electrofílicos para generar derivados de pirrolidina.Además, se describe la síntesis de pirrolizidinas diastereoméricamente enriquecidas a partir de nitroprolinatos enantioméricamente puros a través de una cicloadición 1,3- dipolar multicomponente catalizada por una sal de plata y, por otro lado, una reacción de Amina-Aldehído-Dienófilo (AAD) para sintetizar estructuras ciclohex-2-en-1-ilprolinato como diastereoisómero enantiopuro único de forma multicomponente y libre de metales.

Asymmetries in physisorbed systems give rise to interesting phases and phase transitions in two-dimensional (2D) monolayer and multilayer systems. The effects of asymmetric adsorbate and substrate interactions in monolayers of dipolar molecules on ionic substrates and N2 on graphite are studied. In the case of dipolar molecules on ionic substrates, 2D dielectric phase transitions using a modified Blume-Emery-Griffiths (BEG) model are determined theoretically. A dipole adsorbed vertically above a metal ion lattice site, and pointing up (down), is assigned a spin s=+1 (s=-1). An empty lattice site is assigned a spin S=0. Analytic solutions for both ferroelectrically and antiferroelectrically ordered systems are found. The model is applied to CO adsorbed on MgO and NaCl, and preliminary results for the phase diagram of CH3F on NaCl, are presented. Multilayer phase transitions for N2 on graphite are studied experimentally using synchrotron x-ray diffraction. The system is measured to undergo layering transitions, where the number of layers increases as the temperature of the system increases. A new multilayer phase diagram based on our results and the combined results published by other researchers is presented. The effects of capillary condensation on this multilayer system are quantified, and it is determined that its primary effect is to broaden the discrete layering transitions. The results for both studies are put into context with other adsorption systems with asymmetric interactions.

En esta tesis doctoral se ha estudiado la reacción 1,3-dipolar con iluros de azometino y diferentes dipolarófilos para la síntesis de compuestos ópticamente activos, usando diferentes complejos metálicos compuestos por sales de plata y cobre y diversos ligandos quirales. También se ha estudiado la reacción 1,3-dipolar térmicamente para la funcionalización de grafeno, y posterior uso de dicha funcionalización como soporte de un complejo metálico, el cual fue empleado en catálisis heterogénea.

Silicone oils (polysiloxane) and elastomers are a class of hydrophobic polymers with an extensive range of uses. While the high hydrophobicity can be beneficial in a variety of applications, it is not universally the case. Modification strategies for both fluid and elastomeric polydimethylsiloxane (PDMS) must be employed to create silicones with the appropriate properties for a given application, including enhanced hydrophilicity. Derivatization of PDMS leads to functional silicones with unique properties and added value. Strategies have been developed to modify both fluid and elastomeric PDMS, however, they all have varying degrees of drawbacks: the use of sophisticated equipment or expensive catalysts, restrictions to certain types of solvents, cumbersome multi-step synthetic procedures and surface reversion are some of the challenges faced. There is an opportunity to develop a simple and generic method for the controlled functionalization of PDMS. The Sharpless concept of ‘Click’ chemistry was an ideal approach to solving some of these challenges. Following nature’s lead, these reactions that are modular, wide in scope, high yielding, have simple reaction conditions and generate inoffensive byproducts. Herein, a synthetic method to functionalize silicones using the thermal Huisgen 1,3-dipolar cycloaddition of azides to alkynes is described. Initial exploration focused on the creation of inherently reactive elastomers that could be modified with a model hydrophilic moiety, poly(ethylene glycol). This was extended to the creation of amphiphilic multi-functional polysiloxanes and amphiphilic networks. Furthermore, the ‘Click’ approach was used to solve challenges faced in applications where silicones find use. The method described overcomes silicone modification challenges. The cycloaddition reaction is tolerant to many reaction conditions, is orthoganol to a variety of chemical reactions, does not require the use of a catalyst, the starting functional groups and bonds formed are stable and the reaction is high yielding, positioning the Huisgen ‘click’ reaction is an exceptional synthetic tool for the silicone chemist. / Dissertation / Doctor of Philosophy (PhD) / Polydimethylsiloxane (PDMS or silicone) fluids and elastomers are materials that find use in many applications owing to the many desirable properties they possess; personal care products, electrical insulators, sealants and biomedical are examples of products containing silicone. Native PDMS is highly hydrophobic (water repellent) and certain applications require silicones that are more compatible in environments containing water. Methods have been developed to modify both fluid and elastomeric silicones; incorporation of different molecules or polymers can enhance the properties of silicone for various applications or create unique materials. However, many of these methods have certain drawbacks: the use of sophisticated equipment, expensive ingredients, or a lack of permanence. For this reason, a new method to modify fluid and elastomeric silicones has been developed. The new method is based on the concept of ‘Click’ chemistry and has overcome some of challenges associated with other modification methods.

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