Single crystals of sodium salt of guanosine dihydrate and 9 Ethyl Guanine were X-irradiated with the objective of identifying the radical products. Study with K-band EPR, ENDOR, and ENDOR-Induced EPR techniques indicated at least four radical species to appear in both crystals in the temperature range of 6K to room temperature. Three of these radicals (Radicals R1, R2, and R3) were present immediately after irradiation at 6K. Computational chemistry and EPR spectrum simulation methods were also used to assist in radical identifications. Radical R1, the product of net hydrogen addition to N7, and Radical R2, the product of electron loss from the parent molecule, were observed in both systems. Radical R3, in Na+.Guanosine-.2H2O, is the product of net hydrogen abstraction from C1' of ribose group and radical R3 in 9EtG was left unassigned due to insufficient experimental data. Radical R4, the C8-H addition radical, was also detected in both systems. For Na+.Guanosine-.2H2O, R4 was observed after warming the irradiated crystals to the room temperature. But for the 9EtG crystals the corresponding radical form was detected after irradiation at room temperature. Density functional theory (DFT) based computational studies was conducted to investigate the radical formation mechanisms and their stability. Here possibilities of proton transfers from the neighboring molecules were considered. The first approach was to consider the proton affinities of the acceptor sites and deprotonation enthalpies of the donor sites. This approach supported the formation of radicals observed in both systems. The second approach, applied only to the 9EtG system, was based on proton transfers between 9EtG base-pair anion and cation radicals. Even though the charge and spins were localized as expected, the computed thermodynamic data predicted that the proton transfer processes are unfavorable for both anionic and cationic base-pairs. This indicates the need for additional work to draw final conclusions. In addition, DFT methods were used to compute the geometries and hyperfine coupling constants of 9EtG derived radicals in both single molecule and cluster models. The calculated results agreed well with the experimental results.

When proteins and DNA interact, arginine and lysine are the two amino acids most often in close contact with the DNA. In order to understand the radiation damage to DNA in vivo, which is always associated with protein, it is important to learn the radiation chemistry of arginine and lysine independently, and when complexed to DNA. This work studied X-irradiated single crystals of L-lysine monohydrochloride dihydrate (L-lysine·HCl·2H2O) and L-arginine monohydrochloride monohydrate (L-arginine·HCl·H2O) with EPR, ENDOR, EIE techniques and DFT calculations. In both crystal types irradiated at 66K, the carboxyl anion radical and the decarboxylation radical were detected. DFT calculations supported these assignments. Specifically, the calculations performed on the cluster models for the carboxyl anion radicals reproduced the proton transfers to the carboxyl group from the neighboring molecules through the hydrogen bonds. Moreover, computations supported the identification of one radical type as the guanidyl radical anion with an electron trapped by the guanidyl group. In addition, the radical formed by dehydrogenation of C5 was identified in the L-arginine·HCl·H2O crystals irradiated at 66K. For both crystal types, the deamination radicals and the dehydrogenation radicals were identified following irradiation at 298K. Different conformations of main-chain deamination radicals were detected at 66K and at 298K. In L-lysine·HCl·2H2O, these conformations are the result of the different rotation angles of the side chain. In L-arginine·HCl·H2O, one conformation at 66K has no O-H dipolar protons while the others have two O-H dipolar protons. In L-lysine·HCl·2H2O, two radicals with very similar sets of hyperfine couplings were identified as the result of dehydrogenation from C3 and C5. Two other radicals in low concentration detected only at 66K, were tentatively assigned as the radical dehydrogenated from C3 and the side-chain deamination radical. In L-argnine·HCl·H2O, the radicals from dehydrogenation at C5 and C2 also were identified. DFT calculations supported these assignments and reproduced conformations of these radicals.Finally, based on the radicals detected in the crystal irradated at 66K and at 298K, the annealing experiments from the irradiation at 66K, and the previous studies on the irradiated amino acids, the mechanisms of the irradiation damage on lysinie and arginine were proposed.

No description available.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(地球環境学) / 甲第19156号 / 地環博第131号 / 新制||地環||27 / 32107 / 京都大学大学院地球環境学舎地球環境学専攻 / (主査)准教授 森 晶寿, 教授 劉 徳強, 准教授 吉野 章 / 学位規則第4条第1項該当

L'imagerie de champs magnétiques de faible amplitude avec une résolution spatiale à l'échelle nanométrique est un enjeu important dans de nombreux domaines de la physique et pour de multiples applications, que ce soit par exemple en science des matériaux pour le stockage magnétique de l'information, ou bien en optique quantique afin de pouvoir contrôler un spin individuel utilisé comme bit quantique, ou encore en biophysique pour l'étude structurelle de protéines par résonance magnétique. Dans ce contexte, cette thèse décrit la réalisation d'un magnétomètre à balayage fondé sur la réponse magnétique du spin électronique d'un centre coloré NV du diamant. Un tel magnétomètre présente des propriétés sans équivalent, en combinant une résolution spatiale sub-nanométrique, assurée par la dimension atomique du capteur, et une très haute sensibilité (< 1 µT/Hz^(-1/2)), ceci même à température ambiante. De plus la mesure de champ magnétique est quantitative et non perturbative, offrant ainsi un avantage majeur par rapport à la microscopie à force magnétique couramment utilisée pour l'imagerie magnétique de nanostructures. Nous aborderons, dans un premier temps, les problématiques liées à la fabrication de la sonde magnétique, constituée par un centre coloré NV unique dans un nanocristal de diamant positionné à l'extrémité d'une pointe AFM. Les propriétés de ce magnétomètre seront caractérisées en imageant le champ de fuite d'un disque dur magnétique. Cette étude nous permettra d'introduire différentes méthodes d'imagerie magnétique et de comparer leurs performances. Le magnétomètre à centre NV sera par la suite utilisé pour imager des distributions d'aimantation vortex dans des plots ferromagnétiques, dont le cœur est connu pour être l'un des objets les plus petits du micromagnétisme, le rendant extrêmement difficile à observer. Les propriétés du magnétomètre à centre coloré NV du diamant, démontrées dans cette thèse, ouvrent la voie à de nombreuse études en nanomagnétisme et en spintronique.

Symmetry and symmetry-breaking have, in the last one hundred and fifty years, become incorporated as central explanatory concepts within the natural sciences and mathematics. An abbreviated review of the incorporation of symmetry within the disciplines of mathematics, physics, philosophy and biology, provides a frame within which to develop of a model of mind. This thesis combines the framework provided by symmetry and symmetry-breaking with a structural understanding of self-referential dynamics in examining the implied Kantian model of mind. It considers that Kant’s assumption of a transcendental self unnecessarily isolates consciousness from being understood as a product of complex natural processes. Kant’s structural model of mind is examined and reformulated in terms of a more fundamental form and process. The space required for any non-reductionist model of mind is proposed as being generated through an enfolding of dimensionality in the occurrence of categorical level symmetry breaking during evolutionary development. The temporally extended function is accounted for in terms of self-referential structural dynamics operating within the primary temporal asymmetry. The model of mind proposed is created through application of naturalistic explanations incorporating symmetry and has attributes that may prove of interest to non-reductionists. The phenomenological geometry established provides a framework to understand the experiential phenomenon of qualia while conforming to the requirements of a natural explanation. Information is conceived as being transmitted inwaveforms propagated across spaces of enfolded dimensionalities through structural framesdemarcating nested spaces and condensing in the synthesis of unity in the object of attention,or image, and returning to distribute, the now reformulated, information outward acrosscontextual frames and spaces. This simplified dynamic is considered to operate at all levels of natural phenomena and involves the reintroduction of Bohm’s concepts of implicate and explicate order. The result is a model of mind employing a minimum structural form and self-referential dynamics that has potential for integration across the discipline theoretic frames of the natural sciences while retaining, for the domain of conscious phenomena, an independent causal significance in terms of a temporal structuralism.

Since its discovery in the 1950's, DNP has been a topic of significant interest in magnetic resonance. DNP is the transfer of polarization between single electrons and nuclei, driven by micro-wave irradiation. Since its renaissance at high field in the 90's, due to the introduction of gyrotrons as high-power, high-frequency microwave sources most application of this technique have been samples of biological interest in frozen solution. The long standing interest of our group in the characterization of surface species such as supported catalysts on silica lead us to apply this technique to the study of surfaces. The goal of this thesis is the development of this method, dubbed DNP Surface Enhanced NMR Spectroscopy. To that end, we first introduce new polarizing agents, soluble in organic solvents. The influence of the electron relaxation times on the DNP enhancements is demonstrated and efficient tailored polarizing agents are introduced. The optimization of the sample preparation to obtain optimal sensitivity is also discussed, as well as the interaction between the radical and the surface. These developments made it possible to apply the technique to many functionalized materials, with some examples developed in this manuscript. Finally, the issue of DNP on polarization conductors is discussed, and we show how microcrystals can be efficiently polarized using DNP.

Despite rapid advances in technology, there is currently a complex, and somewhat disjointed approach to the way health information is collected, stored, and organized for both healthcare consumers and professionals. Incompatible electronic medical records from various healthcare providers add to the complexity of a system tasked with delivering a patient’s relevant medical information in a timely manner to the appropriate point of care. Personal health records (PHR) grew out of the efforts to produce an integrated electronic record to manage the multifaceted aspects of healthcare required by both healthcare consumers and professionals. PHRs are a transformative technology with the potential to alter patient-provider relationships in a way that produces a more efficient and cost effective healthcare system as a result of better patient outcomes. PHRs can potentially include a wide variety of users ranging from the lay public to clinical professionals. As such, it is important to identify potential user groups and their corresponding health information needs in order to design PHRs that maximize accessibility, usability, and clinical relevance. This study focused on laypeople who represented a wide age-range of individuals, evenly split in gender, with an above average level of computer literacy. Most of the participants had not used an electronic PHR prior to this study. However, after a hands-on session with PHR software, most participants found it to be easy to use, accompanied with the functionality they expected from such a system. Most participants were satisfied that an electronic PHR would meet their health information needs and would recommend the use of PHRs to family and friends. Anyone in the general public is a potential PHR user. However, this study found that individuals with chronic conditions and those with complex health needs had the most to gain from using a PHR as an integral part of their healthcare routine. This study also demonstrated that an individual’s health condition has a stronger influence on their perceptions about the usefulness of PHRs than does their demographic background (age, education, computer literacy). Finally, this study established that PHRs are considered by participants of the study to be useful tools in meeting their health information needs. / Graduate / 0723 / 0769 / 0984 / dguarin@uvic.ca

Neste trabalho estudou-se a formação de complexos da tirosina e de seus dipeptídeos tirosil-glicina e glicil-tirosina com o íon Cu2+. Para a caracterização destes complexos foram utilizadas as técnicas espectroscópicas de Absorção ótica na região do visível (400 a 800 nm), Ressonância paramagnética eletrônica em duas temperaturas (ambiente e &#8764-150&#176C) e a técnica de fluorescência. No caso da tyr os dados experimentais obtidos pela espectroscopia de RPE sugerem a formação de pelo menos duas espécies distintas de complexos além do cobre hidratado. Os complexos propostos foram: o CuL4 (ao redor de pH 3,5) e o CuL2 (na faixa de pH 4,0 e 12,0). Já para os dipeptídeos são evidenciados três tipos diferentes de complexos. São propostos os seguintes complexos: CuL2 (ao redor de pH 4,5), CuL (H2O) (na faixa de pH 7,0 e 12,0) e CuL(OH)22- (acima de pH 12,0). Os espectros de RPE mostram claramente que com o aumento de pH, ocorre a complexação do Cu2+ com os dipeptídeos. Em pHs altos (acima de pH 10,0) surgem nestes espectros uma estrutura superhiperfina de 5 linhas típicas para a coordenação de Cu2+ com dois nitrogênios. Quanto a tirosina, o espectro de seu complexo com Cu2+, não apresenta estrutura superhiperfina, sendo o sinal obtido, típico do complexo com Cu2+. Da mesma forma que foi observado por RPE, pode-se observar pelos espectros óticos, que em pHs baixos (2,0 a 3,5) para os dipeptídeos, os espectros apresentam uma banda larga e mal-resolvida, característica do íon de Cu2+ livre em solução. Observou-se também um deslocamento do máximo das bandas para o azul, apresentando características típicas das transições d-d correspondentes às várias espécies de complexos do metal em equilíbrio. Os dados de fluorescência foram muito informativos. As titulações da tyr e dos dipeptídeos puros em função do pH permitiram a determinação dos valores de pKs dos grupos ionizáveis. O efeito de supressão de fluorescência devido ao paramagnetismo do cobre foi usado tanto para a determinação da estequiometria quanto para a determinação das constantes de associação dos complexos dos dipeptídeos com Cu2+ em dois pHs fixos (pH 7,0 e 9,0). Encontrou-se complexos com a seguinte estequiometria (ligante/metal) : 2:1 e 1:1 respectivamente para a tyr e para os dipeptídeos nestes pHs. Um modelo simples de equilíbrio foi desenvolvido e estimou-se as constantes de associação da ordem de 107M-1 para os complexos de dipeptídeos- Cu2+. / The main goal of this work was to study the formation of the complexes of tyrosine and its dipeptides tyrosil-glycil and glycil-tyrosine with the transition metal íon Cu2+. The characterization of these complexes was performed through the use of spectroscopic techniques: optical absorption, electron paramagnetic resonance at both room temperature and -150&#176C and fluorescence emission. The EPR spectroscopy suggested for tyrosine two distints species. The following complexes were proposed: CuL4 (pH 3,5) and CuL2 (in the range of pH between 4,0-12,0). Three different complexes were evidentiated for dipeptides- Cu2+: CuL2 (pH 4,5); CuL(H2O) (in the range of pH between 7,0-12,0) and CuL(OH)22- (above pH 12,0). EPR spectra shows clearly the complexation of Cu2+ to the dipeptides. Both at intermediate and high pHs and specially above pH 10,0 a superhyoerfine structure of five lines typical for coordination of copper to two nitrogens was observed. In the case of the aminoacid no superhyperfine structure is observed. EPR data suggest that in a wide pH range between 7,0 and 11,0 the complex formed by the dipeptides was CuL(H2O). Electronic optical absorption was measured at room temperature as a function of pH in the range 2,0-13,0. It was observed that at low pHs (2,0 3,5) the spectra for the dipeptides was characterized by a broad not well resolved band around 800 nm characteristic of hidrated free Cu2+ in water solution. EPR spectra are in agreement with this observation. Increase of pH leads to a blue shift in the absorption band maximum and as a consequence to typical spectra for d-d transitions of the various species of complexes of cooper in equilibrium in solution. Fluorescence data were also very informative. The pure tyr and dipeptides tritation allowed to determine pKs values of ionizable groups. The effect of fluorescence suppression due to paramagnetic copper was used both to establish the stoichiometry of the complexes and the association constants. The stoichiometry of the complexes was determined as 2:1 and 1:1 ligand:metal for tyrosine and the dipeptides respectively at pH 7,0 and pH 9,0. A simple equilibrium model was developed and the association constants for the Cu2+ dipeptides complexes at pH 7,0 and pH 9,0 were estimated to be around 107M-1.

Neste trabalho, dois óxidos de metal de transição com ordem magnética de longo alcance e uma polianilina dopada com plastificante foram estudados através da técnica de ressonância paramagnética eletrônica. O sistema multiferróico óxido de bismuto-manganês, BiMn2O5, foi estudado em sua forma policristalina. Este material apresenta modos de ressonância antiferromagnética que foram identificados a partir de medidas multifrequência em altos campos magnéticos. Estes dados foram ajustados segundo a teoria de Yosida e Nagamiya da ressonância antiferromagnética para obtenção das constantes macroscópicas de anisotropia magnética K1=7.0 x 108 emu Oe mol1 e K2=3.9 x 108 emu Oe mol1, a partir das quais uma estimativa da constate de anisotropia microscópica foi determinada. A caracterização destas grandezas pode ser importante para trabalhos futuros, uma vez que a anisotropia magnética é considerada uma das causas da magnetoelasticidade que dá origem a ferroeletricidade neste material. A ludwigita homometálica de ferro, Fe3O2BO3, foi estudada em sua forma monocristalina. Este óxido de ferro possui uma estrutura com duas sub-redes de ferro praticamente independentes, que se ordenam magneticamente em temperaturas distintas, além de apresentar correlações eletrônicas desde temperatura ambiente. A existência dessas correlações numa dessas estruturas, conhecida como \"escada de três pernas\", foi demonstrada através do espectro de RPE associado com a existência de dímeros Fe3+-Fe2+ nessa estrutura, desde temperatura ambiente até baixas temperaturas. Mostrou-se que os dímeros formam um estado antiferromagneticamente acoplado sujeito a interação de troca dupla, estimando valores da integral de transferência de carga b. Medidas de RPE em filmes automontados de polianilinas dopadas com plastificantes sugerem a população e despopulação de um estado tripleto a partir dos parâmetros dos espectros em função da temperatura, típica de dímeros de spin 1. Diferenças nos parâmetros com ciclagens térmicas sugere o congelamento da estrutura em diferentes estados condizente com a existência de termocromismo nesses polímeros. Enfim, demonstrou-se a relevância da técnica de espectroscopia de ressonância paramagnética eletrônica na caracterização de sistemas sujeitos a interação de troca antiferromagnética. / In this work, two transition metal oxides presenting long range magnetic order and a plastdoped polyaniline were investigated via electron paramagnetic resonance. Polycrystalline samples of the multiferroic manganese oxide, BiMn2O5, showed antiferromagnetic resonance modes which were identified from high magnetic fields multi frequency electron paramagnetic resonance. These data were fitted according to Yosida and Nagamiya theory of antiferromagnetic resonance. The macroscopic constants of magnetic anisotropy K1=7.0 x 108 emu Oe mol1 and K2=3.9 x 108 emu Oe mol1 were obtained from this fitting and allowed for estimating the microscopic constant of anisotropy. Magnetic anisotropy may lead to magnetoelasticity, which is related to the ferroelectricity in this material. Thus, the characterization of this physical quantities may be useful to future research. Single crystals of a homometallic iron ludwigite, Fe3O2BO3, were investigated in its distinct magnetic phases. This system has two independent iron sub-lattices which order magnetically in two distinct temperatures, presenting electronic correlations from room temperature. Despite the broad and superposed lines in the EPR spectra, the presence of such correlations was demonstrated in one of these structures, which is known as three leg ladders (3LL). A dimer Fe3+-Fe2+ was identified at room temperature, showing an antiferromagnetically coupled state subjected to double exchange interactions. The charge transfer integral b was estimated. Temperature sweep EPR measurements in films of plastdoped polyanilines suggested the population and depopulation if a triplet state typical of spin 1 dimers. Differences in the parameters after thermal cycling suggested the freezing of the structure at different states in accordance to observed thermocromism in these polymers. In conclusion, the relevance of the EPR technique was demonstrated to the characterization of exchange coupled systems.