Funktionelle bildgebende Verfahren des Gehirns messen Veränderungen des lokalen cerebralen Blutflusses bzw. der Oxygenierung, die an neuronale Aktivität gekoppelt sind, und nicht die neuronale Aktivität selbst. Diese Veränderungen breiten sich über ein größeres Areal aus als die neuronale Aktivität, das räumliche Auflösungsvermögen der bildgebenden Verfahren bleibt daher begrenzt. Es ist vorgeschlagen worden, dass der Sauerstoffverbrauch unter neuronaler Aktivierung vor dem Blutfluss ansteige. Ein initial steigender Sauerstoffverbrauch würde dann eine Deoxygenierung des Gewebes bewirken, diese bliebe exakt auf das Aeral neuronaler Aktivität beschränkt und liesse sich mit bildgebenden Verfahren darstellen, die die lokale Oxygenierung messen. Um die Hypothese der initialen Deoxygenierung zu überprüfen führten wir Messungen der intravaskulären Sauerstoffkonzentration mittels Phosphorescence Quenching im somatosensorischen Kortex von Ratten unter physiologischer Stimulation (mechanische Auslenkung der Barthaare) durch. Die Tiere wurden mit Chloralose/Urethan anästhesiert und ein kranielles Fenster über dem somatosensorischen Kortex präpariert. Der Zeitverlauf der intravaskulären Sauerstoffkonzentration unter 4s-Stimulation eines einzelnen bzw. aller Barthaare zeigte eine nach ca. 1-1,5s beginnende Hyperoxygenierung, die ihr Maximum etwa 1-1,5s nach Ende der Stimulation erreichte. Es folgte ein gering ausgeprägter post-stimulus-undershoot. Eine reproduzierbare initiale Deoxygenierung liess sich nicht nachweisen. Diese Ergebnisse sind vereinbar mit einer engen Kopplung des lokalen cerebralen Blutflusses an die neuronale Aktivität während der gesamten Stimulationsdauer. / Functional brain imaging techniques such as fMRI or PET measure regional changes in cerebral blood flow and oxygenation related to neuronal activity rather than neuronal activity itself. These changes are believed to spread over a larger area than the neuronal activity thus limiting spatial resolution of imaging techniques. It has been suggested that oxygen consumption increases before blood flow in the region of increased activity. An increased oxygen consumption would lead to an initial deoxygenation limited exactly to the aera of neuronal activity thus providing a signal detectable with techniques measuring blood oxygenation (e.g. BOLD-fMRI). To test the hypothesis of an initial deoxygenation we performed measurements of intravascular oxygen concentration in the somatosensory cortex of rats in response to a physiological stimulus (whisker deflection) using oxygen dependent phosphorescence quenching. Animals were anesthetized with chloralose/urethane and a closed cranial window was implanted over the somatosensory cortex. Timecourses of intravascular oxygen concentration during 4s single-whisker as well as whole pad deflection showed a hyperoxygenation beginning 1-1,5s second after stimulatin onset and peaking one second after the end of the stimulation. A small post-stimulus undershoot was observed. We did not reproducibly detect an initial deoxygenation. These results indicate tight coupling between neuronal activity and cerebral blood flow throughout the stimulation period.

Dans le cadre de la recherche de matériaux fluorescents et/ou phosphorescents à émission blanche, une nouvelle famille d'aluminosilicate de baryum/strontium dopée à l'europium (Ba/Sr)13-xAl22+2xSi10+2xO66:Eu a été étudiée. La première partie de ce mémoire rappelle les mécanismes d'émissions de fluorescence de l'ion Eu2+ et les processus de thermoluminescence (TL). La seconde partie est quant-à-elle consacrée aux conditions de synthèse des matériaux étudiés, à leur caractérisation structurale et leurs propriétés optiques. Typiquement, sous illumination UV, un matériau de la famille sus-mentionnée présente deux bandes de fluorescence (respectivement centrées dans le bleu et le vert du spectre du visible) dues à la présence de Eu2+ dans des sites cristallographiques distincts. Le cation Eu2+ occupe préférentiellement l'un des sites comme nous avons pu le vérifier par calculs ab-initio de type DFT. Les deux bandes d'émissions recouvrant la totalité du spectre du visible donnent lieu à une émission blanche pour l'oeil humain. La variation du taux d'europium et de la proportion Ba/Sr permettent de modifier le rendu colorimétrique de l'émission. Après arrêt de l'excitation UV, le composé présente une phosphorescence blanche visible une dizaine de minutes. Des mesures de déclins d'émission conjointement à des expériences de TL ont permis d'identifier et caractériser les pièges responsables de la phosphorescence. Enfin, l'analyse spectrale de la TL a pu mettre en avant une dépendance des spectres de TL avec la température à laquelle le matériau est excité. Ce phénomène surprenant a fait l'objet d'une analyse détaillée.

Dans le cadre de la recherche de matériaux fluorescents et/ou phosphorescents à émission blanche, une nouvelle famille d'aluminosilicate de baryum/strontium dopée à l'europium (Ba/Sr)13-xAl22+2xSi10+2xO66:Eu a été étudiée. La première partie de ce mémoire rappelle les mécanismes d'émissions de fluorescence de l'ion Eu2+ et les processus de thermoluminescence (TL). La seconde partie est quant-à-elle consacrée aux conditions de synthèse des matériaux étudiés, à leur caractérisation structurale et leurs propriétés optiques. Typiquement, sous illumination UV, un matériau de la famille sus-mentionnée présente deux bandes de fluorescence (respectivement centrées dans le bleu et le vert du spectre du visible) dues à la présence de Eu2+ dans des sites cristallographiques distincts. Le cation Eu2+ occupe préférentiellement l'un des sites comme nous avons pu le vérifier par calculs ab-initio de type DFT. Les deux bandes d'émissions recouvrant la totalité du spectre du visible donnent lieu à une émission blanche pour l'oeil humain. La variation du taux d'europium et de la proportion Ba/Sr permettent de modifier le rendu colorimétrique de l'émission. Après arrêt de l'excitation UV, le composé présente une phosphorescence blanche visible une dizaine de minutes. Des mesures de déclins d'émission conjointement à des expériences de TL ont permis d'identifier et caractériser les pièges responsables de la phosphorescence. Enfin, l'analyse spectrale de la TL a pu mettre en avant une dépendance des spectres de TL avec la température à laquelle le matériau est excité. Ce phénomène surprenant a fait l'objet d'une analyse détaillée.

<p>Highly correlated quantum chemical methods have been appliedto study the photophysical properties of substituted benzenes.With the inclusion of spin-orbit coupling, the phosphorescencesof these molecules have been calculated usingMulti-CongurationalSelf- Consistent Field (MCSCF) quadraticresponse theory. The Herzberg-Teller approximation has beenadopted to evaluate the vibronic contributions tophosphorescence.</p><p>The performance of hybrid density functional theory (DFT) atthe B3LYP level is examined in comparison to the MP2, CCSD andCCSD(T) methods for the geometry and permanent dipole moment ofp-aminobenzoic acid. The time-dependent DFT/B3LYP method isapplied to calculate the two-photon absorption of a series ofZinc-porphyrin derivatives in combination with a two-statemodel. The transitions between excited singlet and tripletstates of Zinc and Platinum based organometallic compounds havebeen computed using DFT quadratic response theory. The resultsare used to simulate the non-linear propagation of laser pulsesthrough these materials utilizing a dynamical wave propagationmethod.</p>

Title: Methods of Study of Photosensitizer-photophysics with Application on Thiazolyl-porphyrins Author: Marek Scholz Department: Department of Chemical Physics and Optics Supervisor: RNDr. Roman Dědic, Ph.D. Supervisor's e-mail address: Roman.Dedic@mff.cuni.cz Abstract: Photodynamic therapy for oncologic and various chronic diseases is a rapidly emerging method of treatment. It is based on the production of highly reactive singlet oxygen and free radicals by excitation energy transfer from the molecules of photosensitizers. Photosensitizers are preferentially accumulated in the target tissues and locally illuminated. This way produced reactive species cause apoptosis or necrosis of the cells leading to the desired therapeutic effect. Synthesis and subsequent photophysical characterization of photosensitizing dyes is a fundamental part of the development of photodynamic methods. The main aim of the work is to explain the most widely used methods of photophysical study of photosensitizers and apply them to new synthesized photosensitizers: thiazolyl-porphyrins. Methods of absorption and fluorescence spectroscopy, flash- photolysis, time- and spectral-resolved detection of luminescence, optoacoustic spectroscopy and other spectroscopic methods were used. Thiazolyl-porphyrins proved to be promising new...

Como parte do principal programa do Laboratório de Cristais Iônicos do Departamento de Física Nuclear do Instituto de Física da Universidade de São Paulo, foi estudado no presente trabalho o mineral natural de cordierita, de fórmula química (Mg,Fe)(Al4Si5O18) . nH2O, amostra esta de Vana, oriunda da Bahia. O trabalho teve como enfoque as propriedades de termoluminescência (TL) e de ressonância paramagnética eletrônica (EPR). Foram obtidas curvas de emissão TL de uma amostra com dose adicional de 50 Gy no aparelho leitor montado no LACIFID, e outra de uma amostra com dose adicional de 2000 Gy no aparelho leitor do fabricante Daybreak Nuclear. As duas curvas apresentam um pico único aparente em torno de l50°C, estendendo-se de 50°C a 250°C. A curva de emissão TL da amostra com dose adicional de 2000 Gy apresentou um ombro muito pouco eminente entre 200\"C e250\"C, indicando a presença de outro pico nessa região. As amostras de cordierita com doses adicionais entre 50 Gy e 5000 Gy deram origem a curvas de emissão TL que mostram que deve haver um pico em torno de 100°C, instável à temperatura ambiente, e que quando é feita a leitura TL imediatamente após a irradiação das amostras, esse pico cresce muito rapidamente, dando a impressão de que o pico em 150°C deslocou-se para temperaturas menores. Na representação gráfica linear, a intensidade TL em função da dose é dada por uma curva exponencial do tipo I = I0[1 - exp (-D/DS)], onde I0 é a intensidade TL de saturação e DS a dose a partir da qual começa a saturação. No presente caso, para o pico TL em torno de 100°C, foram obtidos I0 ~- 4,6x105 em unidades arbitrárias, e Ds ~ 2000 Gy. Na escala logarítmica, obtém-se uma reta paralela à da linearidade, isto é, o pico TL em 100°C cresce linearmente com a dose. No entanto, o pico no intervalo 145°C 150°C apresenta supralinearidade; não muito acentuada, mas desde baixa dose (menos de 10 Gy), tornando-se sublinear em aproximadamente 800 Gy. O recozimento a uma temperatura de 600°C por uma hora antes da irradiação (no caso 500 Gy), provocou um aumento na sensibilidade do pico em 100°C, enquanto que com o recozimento a750°C por uma hora, a intensidade TL em 125°C é que sofreu aumento, e com o recozimento a 900°C por uma hora o que sofre aumento na intensidade é o pico no intervalo 145-150°C, de tal modo que dá a impressão de que o pico TL se desloca de 100°C para 150°C com o tratamento térmico de 600°C a 900°C por uma hora. O tratamento térmico isócrono a 72°C, 96°C, 116°C, 136°C, 150°C, 176°C, 196°C, 216°C, 228°C, 240°C, 260°C, 280°C e 300°C, mostrou que deve haver picos TL nos intervalos 130°C 140°C, 150°C 170°C, 210°C 220°C, 250°C 260°C e em 360°C. Com a deconvolução da curva de emissão, temos a confirmação desses picos. A determinação dos parâmetros E e s, relativos ao pico em torno de 145°C das curvas de emissão TL das Figuras VII-2 (a) e (b), foi feita usando o método de duas taxas de aquecimento, com o seguinte resultado: E = 1,305 eV e s = 3,569x1014 s-1. O método de E x Tstop desenvolvido por McKeever (1985), resultou, por outro lado, em vários patamares de energia, indicando vários picos nas regiões de 70-90°C, 95-105°C, 115-118°C, 132-138°C, 155-165°C, 175-195°C. O método de deconvolução da curva de emissão, introduzido por Gomez - Ros et al (1998), mostrou a existência de picos TL em 144°C (E = 0,98 eV; s = 1,715 x 1011 s-1), 178°C (E = 0,995 eV; s = 2,792x1010 s-1), 214°C (E = 1,13eV; s = 1,026 x 1011 s-10), 249°C (E = 1,15 eV; s = 2,323 x 1010 s-1) e 368°C (E = 1,19 eV; s = 2,824x108 s-1). O espectro de EPR da amostra natural apresentou: na região entre 2000 e 3600 Gauss, seis linhas características de Mn2+; em 1500 Gauss, a linha de Fe3+; e centrada em 3400 Gauss, a linha larga devido à interação dipolar de Fe3+. Outras linhas não foram identificadas. O tratamento térmico a 600°C por uma hora não fez se apresentarem novas linhas ou causou supressão de algumas, mas a linha de interação dipolar sofreu um aumento considerável, indicando que o tratamento térmico causou a transformação de Fe2+ em Fe3+, liberando elétrons. / The Ionic Crystals Laboratory at Physics Institute of the Sao Paulo University investigates, as its main research project, studies of physical properties of available natural Brazilian minerals of silicates. In the present work, thermoluminescense and electron paramagnetic resonance properties of cordierite, (Mg,Fe)(Al4Si5O18) . nH2O, from Vana, Bahia State have been investigated. Being natural mineral, a x-ray fluorescence analysis has been conducted, finding first of all 47 ,77 mol % of SiO2, 31,70 of Al2O3, 7,52 of MgO and 8,31 mol % of FeO, as basic component, of the cordierite crystal, and 0,287 mol% of MnO, 0,84 mol% of Na2O, 0,46 mol% CaO, 0,3 mol% K2O, 0,022mol% of TiO2 and several others in smaller concentration. Glow curves, one of a natural sample with 50 Gy additional -dose, registered in a indigenous TL reader and the other one of a natural sample irradiated to 2000 Gy additional dose obtained in Daybreak TL reader. Both glow curves are characterized by a very broad (from 50°C to 250°C) curve peaked at 150°C. The second glow curve, presents a light shoulder around 200 to 250°C. Anyway, in such a case, one expects more than two peaks composing that broad glow curve. The cordierite samples irradiated with different additional -doses in the range 50 - 5000 Gy, have originated TL glow curves that demonstrate the possible existence of a peak around 100°C, unstable in ambient temperature, but if it is read soon after irradiation, the glow curves show this peak increasing quickly, appearing that the peak around 150°C shifted itself toward smaller temperatures. In the linear representation, the TL intensity as function of the dose, is given by an exponential curve in the form I = I0[ - exp(-D/Ds)], where I0 is the TL saturation intensity and Ds is the dose of the beginning of the saturation. In the present case, I0 ~ 4,1 x 105 (arbitrary units) and Ds ~ 2000 Gy were obtained. In the logarithmic scale, it has been obtained a parallel to straight line of linearity for the 100°C TL peak. However, the peak TL around 145-150°C, presents supralinearity, not much pronounced, from low doses (below 10 Gy) up to 800 Gy; after that, becomes sublinear. The pre-irradiation annealing at 600°C/1h, has provoked an enhancement of sensibility of the 100°C peak; the pre-irradiation annealing at 750°C/1h has originated an enhancement of TL intensity of the 125°C peak; at 900°C/1h has originated an enhancement of TL intensity of the peak around 145-150°C; as consequence the TL peak seems to shift from 100°C to 150°C. The isochronous thermal treatment at 72°C, 96°C, 116°C, 136°C, 150°C, 176°C, 196°C, 216°C, 228°C, 240°C, 260°C, 280°C and 300°C, has shown the possible existence of TL peaks in the ranges 130°C 140°C, 150°C 170°C, 210°C 220°C, 250°C 260°C and at 360°C. The glow curve deconvolution calculation confirms the presence of these peaks. The determination of the parameters E and s, relative to peak around 145°C of the glow curves - Figures VII.2 (a) and (b) - was done by the method of two heating rates, and resulted: E ~ 1,305 eV and s ~ 3,569 x 1014 s-1. The E x Tstop method, developed by McKeever (1995), gives, on the other hand, several plateaus, indicating several peaks in the ranges 70-90°C, 95-105°C, 115-118°C, 132-138°C, 155-165°C, 175-195°C. E - values can be inferred from each plateau. The glow curve deconvolution, method developed by Gomez - Ros et al. (1998), has shown the existence of TL peaks at 144°C (E = 0,98 eV; s = 1,715 x 1011 s-1), 178°C (E = 0,995 eV; s = 2,792x1010 s-1), 214°C (E = 1,13eV; s = 1,026 x 1011 s-10), 249°C (E = 1,15 eV; s = 2,323 x 1010 s-1) e 368°C (E = 1,19 eV; s = 2,824x108 s-1). The EPR spectrum of the natural sample has presented in the interval of 3000 to 3600 Gauss 6 characteristic lines of Mn2+, the line of Fe3+ at 1500 Gauss and a broad line centered at 3400 Gauss owing to dipolar interaction of Fe3+. Other lines were not identified. The thermal treatment at 600°C/1h did not produce new EPR lines, neither suppressed other ones. On the other hand, the dipolar interaction line had a considerable increment, indicating that with the thermal treatment there happened the conversion from Fe2+ to Fe3+, releasing electrons, since the broad line around 3400 Gauss, due to dipolar interaction of Fe3+ - ions increased with this heat treatment.

La phosphorescence est une émission lumineuse perdurant après l'arrêt de l'excitation, due à un piégeage par des défauts de la matrice des porteurs de charges formés durant l'excitation, puis à leur dépiégeage progressif avec l'énergie thermique à température ambiante, suivi de leur recombinaison radiative. Le premier objectif de la thèse était la compréhension des mécanismes de phosphorescence, jusqu'alors inconnus. La phosphorescence du matériau le plus ancien, ZnS:Cu+,Co2+, est due au piégeage d'électrons sur des lacunes de soufre distantes de l'activateur Cu+. La luminescence est associée à la recombinaison radiative depuis la bande de conduction (bleu) ou une lacune anionique plus ou moins proche de Cu+ (vert, rouge) vers les orbitales 3d de Cu+. La phosphorescence du matériau le plus performant, SrAl2O4:Eu2+,Dy3+,B3+, est due au piégeage d'électrons sur des lacunes d'oxygène proches de l'activateur Eu2+. La seconde émission observable à basse température est due à un transfert de charge entre les ions Eu3+ résiduels et O2-, et est associée à un piégeage de trous. Des règles générales sont dégagées pour le piégeage dans tous les matériaux phosphorescents : lacunes anioniques proches des activateurs pour Eu2+, Ce3+, Tb3+ et Pr3+, lacunes anioniques éloignées des activateurs pour Cu+ et Mn2+, lacunes cationiques pour les activateurs Eu3+, Tm3+ et Sm3+. Un nouveau modèle est établi sur l'agglomération et la stabilisation des défauts quel que soit le défaut de charge qu'ils induisent, avec des comparaisons d'énergies d'ionisation. Ce modèle permet une approche prédictive de la synthèse de nouveaux matériaux phosphorescents, ainsi qu'une approche raisonnée de l'optimisation de la fluorescence de certains luminophores. Le second objectif de la thèse était la découverte de nouveaux matériaux phosphorescents. Plusieurs matrices dopées par Eu2+ ont été trouvées phosphorescentes, parmi lesquelles principalement (Ca,Sr)Al2Si2O8:Eu2+,Pr3+ (brevetée par Rhodia Electronics and Catalysis et le CNRS), émettant pendant quelques heures avec une nouvelle couleur bleu très clair.

<p>Oscillator strengths and transition energies are calculated for several mono-substitutes of benzene and naphthalene molecules. The substituents investigated are chlorine, bromine and iodine. Calculations for these molecules are presented, at the Hartree-Fock and DFT level of theory. The functional used in DFT is CAM-B3LYP.</p>

Oscillator strengths and transition energies are calculated for several mono-substitutes of benzene and naphthalene molecules. The substituents investigated are chlorine, bromine and iodine. Calculations for these molecules are presented, at the Hartree-Fock and DFT level of theory. The functional used in DFT is CAM-B3LYP.

Because oxygen is vital to the metabolic processes of all eukaryotic cells, a detailed understanding of its transport and consumption is of great interest to researchers. Existing methods of quantifying oxygen delivery and consumption are non-ideal for in vivo measurements. They either lack the three-dimensional spatial resolution needed, are invasive and disturb the local physiology, or they rely on hemoglobin spectroscopy, which is not a direct measure of the oxygen available to cells. Consequently, many fundamental physiology research questions remain unanswered. This dissertation presents our development of a novel in vivo oxygen measurement technique that seeks to address the shortcomings of existing methods. Specifically, we have combined two-photon microscopy with phosphorescence quenching oximetry to produce a system that is capable of performing depth-resolved, high-resolution dissolved oxygen concentration (PO2) measurements. Furthermore, the new technique allows for simultaneous visualization of the micro-vasculature and measurement of blood velocity. We demonstrate the technique by quantifying PO2 in rodent cortical vasculature under normal and pathophysiologic conditions. We also demonstrate the technique’s usefulness in examining the changes in oxygen transport that result from acute focal ischemia in rodent animal models. / text