In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.

In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.

In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.

In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.

In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.

In this thesis, the effects of simple shear flow on macromolecular structure and interactions are investigated in detail via a combination of Nuclear Magnetic Resonance (NMR) spectroscopy and rheology, namely Rheo-NMR. A specially designed NMR couette shear cell and benchtop shear cell, developed in-house, demonstrated that the direct measurement of the above phenomena is possible. First, to determine whether the shear cells were creating simple shear flow, results were reproduced from literature studies of liquid crystal systems which report shear effects on: Cetyl Trimethyl Ammonium Bromide (CTAB) in deuterium oxide, and Poly(gamma-benzyl-L-glutamate) (PBLG) in m-cresol. Next, the possible conformational changes to protein structure brought about by shear were investigated by applying shear to Bovine -lactogobulin ( -Lg). As the protein was sheared, a small, irreversible conformational change was observed by means of one-dimensional and two-dimensional 1H NMR with reasonable reproducibility. However, no observable change was detected by means of light scattering. A large conformational change was observed after shearing a destabilized -Lg sample containing 10% Trifluoroethanol (TFE) (v/v). From an NMR point of view, the sheared state was similar to the structure of -Lg containing large amounts of -helices and, interestingly, similar to the structure of -Lg containing -sheet amyloid fibrils. Gel electrophoresis tests suggested that the changes were caused by hydrophobic interactions. Unfortunately, this proved to be difficult to reproduce. The effect of shear on an inter-macromolecular interaction was investigated by applying shear during an enzyme reaction of pectin methylesterase (PME) on pectin. Experimental method and analysis developments are described in detail. It was observed that under the conditions studied, shear does not interfere with the de-esterification of pectin with two types of PME, which have different action mechanisms at average shear rates up to 1570 s-1.

<p>In this thesis, material properties have been examined under extreme conditions in computer-based calculations.</p><p>The research on iron (Fe), nickel (Ni), and ferropericlase (Mg_1-xFe_xO) are not only important for our understanding of the Earth, but also for an improved knowledge of these materials <i>per se</i>.</p><p>An embedded-atom model for Fe demonstrated to reproduce properties such as structure factors, densities and diffusion constants, and was employed to evaluate temperature gradients at Earth core conditions. A similar interaction together with a two-temperature method was applied for the analysis of shock-induced melting of Ni. For Mg_1-xFe_xO, the magnetic transition pressure was shown to increase with iron content. Furthermore, the C₄₄ softening with pressure and iron composition supports the experimentally observed phase transition for Mg_0.8Fe_0.2O at 35 GPa.</p><p>The properties of high density helium (He) is of great interest as the gas is one of the most abundant elements in the solar system. Furthermore, He and neon (Ne) are often used as pressure media in diamond anvil cells. The melting of He showed a possible fcc-bcc-liquid transition starting at T=340 K, P=22 GPa with a Buckingham potential, whereas the bcc phase was not seen with the Aziz form. For Ne, Monte Carlo calculations at ambient pressure showed very accurate results when extrapolating the melting temperatures to an infinite cluster limit. At high pressure, a one-phase <i>ab initio</i> melting curve showed a match with one-phase L-J potential results, which could imply a correspondence between <i>ab initio</i>/classical one-phase/two-phase calculations.</p><p>In the search for hard materials, <i>ab initio</i> calculations for four TiO₂ phases were compared. Just as imposed by experiment, the cotunnite phase was found to be very hard. The anomalous elastic behavior of the superconducting group-<i>V</i> metals V, Nb, Ta was found to be related to shrinking nesting vectors and the electronic topological transition (ETT).</p>

L'objectif de ce travail est de progresser dans la compréhension du mécanisme de la réaction d'échange pour les phases Hydroxydes Doubles Lamellaires (HDL). Ainsi, les propriétés d'échange des phases Zn2Cr et Zn2Al ont été examinées pour différents anions inorganiques (Cl-, F-, CO32-,SO42-, Fe(CN)63- et organiques (tartrate, succinate, adipate, styréne-4-sulfonate). Ces échanges ont été suivis par diffraction des rayons X en dispersion d'énergie (EDXRD : Energy Dispersive X-ray Diffraction) utilisant le rayonnement synchrotron. Cette technique compatible avec une étude structurale en solution in situ en cours de réaction, nous a permis de montrer l'existence de deux chemins d'échange : une conversion directe lors de l'échange d'anions inorganiques par des anions inorganiques et un processus en deux étapes avec la formation d'un composé intermédiaire dit "de stade 2" i.e. obtenu par l'échange d'un interfeuillet sur deux, dans le cas de l'échange d'anions inorganiques par des anions organiques. Ce phénomène d'intercalation par stade serait une particularité de l'échange inorganique-organique. Une corrélation peut également être établie avec la différence d'affinité des anions pour les phases HDL, qui semble indiquer que l'échange procède par stade lorsqu'il est défavorable

Este trabalho teve como finalidade o desenvolvimento de uma técnica de carga para armadilhas magnéticas-óticas. Nosso objetivo com este desenvolvimento foi aumentar a eficiência do aprisionamento de modo a possibilitar sua utilização como etapa inicial na geração de condensados de Bose-Einstein. Com este intuito utilizamos feixes atômicos desacelerados em substituição a liberação de vapor na câmara da armadilha, desta forma eliminando as limitações no vácuo. O elemento distintivo de nossa técnica se baseou na utilização de um disco opaco. Este possuía a função de gerar uma sombra no laser responsável pela desaceleração dos átomos. Ao projetar esta sombra sobre a região de formação da armadilha evitamos os efeitos destrutivos do laser sobre a mesma. Desta maneira conseguimos aumentar consideravelmente o número de átomos aprisionados excepcionalmente em relação a carga a partir vapor, atingindo um número de 7.108 e densidade de 1010 átomos/cm3 numa situação otimizada / The goal was to learn and to develop efficient techniques to be used for quickly loading magneto optical traps. It may become usefull during the first steps towards producing Bose-Einstein condensates. A few different aproaches were attempted in order to avoid the loading from the surrounding thermal vapor. The key factor was the use of an opaque, disc shapped, laser beam block. It was imprinted onto one facet of an optical glass slab and then imaged into the trapping region producing a dark shadow there. This blackned region was found to eliminate the harmful effects of the near resonant light from the decelerating laser beam, which is able to pump a significant fraction of the captured atoms out of the trap. Therefore, we were able to signicantly improve the overall trapping efficiency and the number of atoms captured from the decelerated atomic beam. In the optimal configuration, we counted 7x108 trapped atoms with number densities as high as 1010 atoms/cm3

O complexo formado pela molécula de tetraciclina com o íon de magnésio é capaz de impedir a replicação do material genético no ribossomo bacteriano, tornando a tetraciclina um excelente antibiótico. Outra aplicação da tetraciclina, ligada ao íon európio, consiste em estimar a concentração de colesterol no sangue a partir das mudanças do espectro de emissão. Tal técnica apresenta uma resposta imediata e confiável, comparada às técnicas atuais. Emgeral, o espectro de absorção e emissão da tetraciclina é bastante sensível aos íons alojados e ao pH do solvente que o conjunto está imerso. Entretanto, o espectro de absorção teórico em solvente foi obtido com simples modelos contínuos que não consideram interações específicas impostas pelo ambiente no líquido, além da escassez de estudos teóricos para os complexos. Nossa proposta é obter o espectro de absorção eletrônica da tetraciclina e dos complexos formados com os íons Mg e Eu. Além disso, analisamos as mudanças de intensidade e deslocamentos dos máximos das bandas nos sistemas mencionados, em função do pH do solvente e do posicionamento do íon, estimando seu correto posicionamento. Realizamos a simulação clássica usando a técnica de Monte Carlo aplicando o potencial de Lennard-Jones mais Coulomb para cada átomo da molécula de tetraciclina e dos complexos em água. O espectro de absorção eletrônica foi obtido a partir da teoria funcional da densidade dependente do tempo considerando diversos modelos para descrição do solvente e do íon. Em geral, obtivemos uma boa descrição qualitativa dos espectros, quando comparado com os resultados experimentais. Os deslocamentos das bandas e mudanças de intensidades foram bem descritos pelos modelos que utilizaram a simulação clássica para gerar as configurações. Porém cada modelo privilegiou uma propriedade de um determinado sistema, tanto para as diferentes formas da tetraciclina quanto para a presença de íons. Palavras-chaves: tetraciclina, magnésio-tetraciclina, európio-tetraciclina, espectro de absorção, teoria do funcional da densidade dependente do tempo, simulação por Monte Carlo / The complex formed by the tetracycline molecule with the magnesium ion is able to avoid the replication of the genetic material in bacterial ribosome, making tetracycline an excellent antibiotic. Another application of tetracycline attached to the europium ion, is to evaluate the concentration of cholesterol in the blood from the changes in the emission spectrum. This technique presents an immediate and reliable response compared to current techniques. In general, the absorption and emission spectrum of tetracycline is sensitive to ions coupled and the pH of the solvent that the complex is immersed. However, the theoretical absorption spectrum in solvent was obtained with simple continuum models that do not consider specific interactions imposed by the liquid environment, and also the lack of theoretical studies for the complexes. Our proposal is to obtain the electronic absorption spectrum of tetracycline and complexes formed with the ions Mg and Eu. In addition, we analyze the changes in intensity and peak shifts of the bands in the systems mentioned as the function of pH of the solvent and the position of the ion, and estimating the correct position of the ion. We performed a simulation using the classical Monte Carlo technique applying the Lennard-Jones plus Coulomb potential for each atom of the molecule tetracycline and complexes in water. The electronic absorption spectrum was obtained with the time dependent density functional theory considering several models to describe the solvent and ion. In general, we obtained a good qualitative description of the spectra when compared to the experimental results. The shift of the bands and intensity changes were well described by the used models on classical simulation. However, each model favored one property of the system, both for the different forms of tetracycline and for the presence of ions. Keywords: tetracycline, magnesium-tetracycline, europium-tetracycline, absorption spectrum, time dependent density functional theory, Monte Carlo simulation