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1
Graffunder, Corinne Meltzer Weiner Bryan J. "Strengthening the prevention support system in CDC's Rape Prevention and Education RPE program." Chapel Hill, N.C. : University of North Carolina at Chapel Hill, 2008. http://dc.lib.unc.edu/u?/etd,2093.
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Thesis (DrPH)--University of North Carolina at Chapel Hill, 2008.Title from electronic title page (viewed Feb. 17, 2009). "... in partial fulfillment of the requirements for the degree of Doctor of Public Health in the Department of Public Health." Discipline: Public Health; Department/School: Public Health.
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Niang, Awa. "RPE et relaxation de composites moléculaires bidimensionnels." Toulouse 3, 1994. http://www.theses.fr/1994TOU30153.
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Nous avons etudie par resonance paramagnetique electronique en bande x l'anisotropie de la largeur de raie et du facteur g des composites moleculaires bidimensionnels de type perovskite feuillete nh#3-r-nh#3mx#4. Les mesures ont ete effectuees sur des monocristaux et des poudres en fonction de la temperature (de 4. 2 a 290k). Le temps de relaxation spin-reseau t#1 a egalement ete mesure par la methode de modulation en fonction de la temperature. Les echantillons presentent des structures et des interactions de couplage differentes suivant la nature de l'halogene x, du metal m et du radical organique r. Nous avons analyse l'influence de ces parametres sur le comportement des spins par l'etude des echantillons nh#3-(ch#2)#n-nh#3mx#4 m = (manganese, cuivre. ), x (chlore, brome) et n = 2,3,4,5. Lorsque r est compose de molecules ayant des liaisons insaturees ces materiaux constituent d'excellentes matrices pour des reactions de polymerisation selectives par irradiation ou par traitement thermique. Nous avons effectue des mesures de rpe et de relaxation spin-reseau sur le complexe de propargylamine et de chlorure de cadmium hcc-ch#2-nh#3#2cdcl#4 chauffe. L'interpretation des resultats s'effectue en tenant compte de la forte interaction d'echange presente dans ces echantillons et des differentes interactions de couplage. Les dependances de t#1 sont interpretees en utilisant le modele des trois reservoirs de bloembergen et wang. Les resultats mettent en evidence la diffusion des spins lorsque le metal est le manganese et la presence d'une interaction d'echange antisymetrique modulee par les phonons dans le cas du cuivre. La nature de l'halogene joue egalement un role important dans la dynamique des spins et notamment dans la relaxation spin-reseau. Les resultats obtenus sur hcc-ch#2-nh#3#2cdcl#4 chauffe sous vide mettent en evidence la creation d'un nombre important de centres paramagnetiques due a la disparition des triples liaisons et par consequent une forte interaction d'echange
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Assis, Alice [UNESP]. "Ressonância paramagnética eletrônica (RPE) aplicada em semicondutores orgânicos." Universidade Estadual Paulista (UNESP), 2012. http://hdl.handle.net/11449/99662.
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Um importante fator para a vida útil de dispositivos emissores de luz que utilizam compostos organometálicos como material emissor é a compreensão do seu mecanismo de degradação. O principal mecanismo de degradação destes materiais é a dissociação reversível/irreversível entre o átomo metálico central e um de seus ligantes após a excitação da molécula emissora. O complexo de carga formado em decorrência da dissociação irreversível pode ser sensível a campos magnéticos aplicados, através da interação do campo com o elétron desemparelhado. Desta forma, neste trabalho foram avaliados, através de medidas de ressonância paramagnética eletrônica (RPE), os possíveis processos de degradação em sistemas contendo a dispersão de dois compostos organometálicos fac tris(2-fenilpiridina) irídico (ir(ppy)3) e irídio bis(4,6-diflúorfenil)-piridinato-N, C2) picolinato (Flrpic) em diferentes matizes poliméricas como o poliestireno (PS), o poli(9,9-dioctifluoreno-2,7-dil) (PFO) e o polimetilmetacrilato (PMMA). Foi avaliada ainda a influência da molécula doadora de cargas 1,2,4,5-tetracianobenzeno (TCNB) na dispersão Flrpic+PS. Os processos de degradação foram estudados através da análise de diversos parâmetros, como o comportamento do sinal de RPE com a fotoexcitação, processo de relaxação do sinal em diferentes temperaturas e à avaliação do sinal de RPE dos compostos organometálicos puros e nas diferenetes dispersões em matizes poliméticas. Os resultados mostraram que um sinal de RPE relativamento baixo é obtido para o composto Flrpic puro. Entretanto a sua inserção em matrizes poliméricas promoveu um aumento significativo da intensidade do sinal. Dados de absorção e emissão óptica dos compostos evidenciaram que espécies excitadas são inicialmente fotogenadas nos complexos metálicos...
Understanding the degradation mechanism of light emitting devices based on organometallic compounds is the major point to improve their life time. The main mechanism of degradation of these materials is the reversible/irreversible dissociation between the central metallic atom and one of its ligands after the excitation of the emiting molecule. The carge complex formed due to the irreversible dissociation may be sensitive to applied magnetic fields through the field interaction with the unpaired electron. Thus, in this study the possible degradation processes in dispersion systems composed by two organometallic compounds Iridium(III)bis(4,6-fluorephenyl)-pyridiano-N, C2]picolinate (Flrpic) and iridium(III)fac-tris(2-phenylpyridine) (Ir (ppy)3) in different polymer matrices (polystyrene (PS), poly(methylmethacrylate) (PMMA) and poly(9,9-dioctylfluorene) (PFO) were analysed through electron paramagnetic resonance (ERP) technique. The influence of a charge donor molecule 1,2,4,5-tetracyanobenzene (TCNB) in Flrpic+PS dispersion was also examined. The processes of degradation were studied by analysing a variety of parameters such as the behaviour or the EPR signal with the photoexcitation, the process of signal relaxation at different temperatures and the evaluation of the EPR signal of pure organometallic compounds and its dispersion in different polymeric matrices. The results showed that a relatively low EPR signal is obtained for pure Flrpic compound. However its insertion in polymeric matrices caused a significant increase in the signal intensity. The optical absorption and emission data have shown that the excited species are initially photogenerated in metal complexes of those compounds, promoting the subsequent formation of paramagnetic centres, close to Indium atom. The energy levels analysis also suggests an exciton trapping process, which were associated with... (Complete abstract click electronic access below)
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Stein, Roberto de Mello. "RPE em compostos de grafite intercalado com ALCL3." [s.n.], 1985. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277549.
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Orientador: Carlos RettoriTese (doutorado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: Nós mostramos que no Composto de Grafite Intercalado com AlCl3, tipo aceitador, a dependência com a temperatura da resistividade no plano e na direção do eixo-c entre 100K e 300K, pode ser obtida experimentalmente através da análise da intensidade e da forma da linha da ressonância de spin dos portadores de carga. Os resultados indicam um comportamento metálico e do tipo salto por ativação térmica para o transporte de carga no plano e no eixo-c, respectivamente. A análise da ressonância no grafite puro apresenta dentro do erro experimental, a dependência com a temperatura esperada para a resistividade no plano e no eixo-c e uma susceptibilidade que independe da temperatura. A dependência da largura da linha é atribuída a dependência com a temperatura da mobilidade dos portadores e da razão entre a probabilidade de transição para "spin-flip" devido ao acoplamento spin-órbita e o espalhamento coulombiano. Para estágios um e sete os parâmetros da ressonância revelam uma transição de fase a 210K e 168K respectivamente
Abstract: We show that the temperature dependence of the in-plane and c-axis resitivities between 100K and 300K for the acceptor AlCl3 - Graphite Intercalated Compounds can be obtained from the analysis of the intensity and lineshape of the resonance in a conduction carrier spin resonance experiment. The results suggest a metallic and thermal activated hopping like character for the in-plane and c-axis charge transport respectively. The analysis of the resonance for pure graphite gives, within the experimental accuracy, the expected temperature dependence for the in-plane and c-axis resistivities, and an almost temperature independent Pauli paramagnetic susceptibility. The temperature dependence of the linewidth is attributed to the dependence of both the carrier s mobility and the ratio between the transition probability for spin-flip due to spin-orbit coupling and the coulomb scattering. For stage one and seven the resonance parameters reveal a phase transition at 210K and 168K respectively
Doutorado
Física
Doutor em Ciências
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Assis, Andrei Paulo de. "Ressonância paramagnética eletrônica (RPE) aplicada em semicondutores orgânicos /." Bauru, 2012. http://hdl.handle.net/11449/99662.
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Orientador: Carlos Frederico de Oliveira GraeffBanca: Claudio José Magon
Banca: José Humberto Dias da Silva
O Programa de Pós Graduação em Ciência e Tecnologia de Materiais, POSMAT, tem caráter institucional e integra as atividades de pesquisa em materiais em diversos campi
Resumo: Um importante fator para a vida útil de dispositivos emissores de luz que utilizam compostos organometálicos como material emissor é a compreensão do seu mecanismo de degradação. O principal mecanismo de degradação destes materiais é a dissociação reversível/irreversível entre o átomo metálico central e um de seus ligantes após a excitação da molécula emissora. O complexo de carga formado em decorrência da dissociação irreversível pode ser sensível a campos magnéticos aplicados, através da interação do campo com o elétron desemparelhado. Desta forma, neste trabalho foram avaliados, através de medidas de ressonância paramagnética eletrônica (RPE), os possíveis processos de degradação em sistemas contendo a dispersão de dois compostos organometálicos fac tris(2-fenilpiridina) irídico (ir(ppy)3) e irídio bis(4,6-diflúorfenil)-piridinato-N, C2) picolinato (Flrpic) em diferentes matizes poliméricas como o poliestireno (PS), o poli(9,9-dioctifluoreno-2,7-dil) (PFO) e o polimetilmetacrilato (PMMA). Foi avaliada ainda a influência da molécula doadora de cargas 1,2,4,5-tetracianobenzeno (TCNB) na dispersão Flrpic+PS. Os processos de degradação foram estudados através da análise de diversos parâmetros, como o comportamento do sinal de RPE com a fotoexcitação, processo de relaxação do sinal em diferentes temperaturas e à avaliação do sinal de RPE dos compostos organometálicos puros e nas diferenetes dispersões em matizes poliméticas. Os resultados mostraram que um sinal de RPE relativamento baixo é obtido para o composto Flrpic puro. Entretanto a sua inserção em matrizes poliméricas promoveu um aumento significativo da intensidade do sinal. Dados de absorção e emissão óptica dos compostos evidenciaram que espécies excitadas são inicialmente fotogenadas nos complexos metálicos...
Abstract: Understanding the degradation mechanism of light emitting devices based on organometallic compounds is the major point to improve their life time. The main mechanism of degradation of these materials is the reversible/irreversible dissociation between the central metallic atom and one of its ligands after the excitation of the emiting molecule. The carge complex formed due to the irreversible dissociation may be sensitive to applied magnetic fields through the field interaction with the unpaired electron. Thus, in this study the possible degradation processes in dispersion systems composed by two organometallic compounds Iridium(III)bis(4,6-fluorephenyl)-pyridiano-N, C2]picolinate (Flrpic) and iridium(III)fac-tris(2-phenylpyridine) (Ir (ppy)3) in different polymer matrices (polystyrene (PS), poly(methylmethacrylate) (PMMA) and poly(9,9-dioctylfluorene) (PFO) were analysed through electron paramagnetic resonance (ERP) technique. The influence of a charge donor molecule 1,2,4,5-tetracyanobenzene (TCNB) in Flrpic+PS dispersion was also examined. The processes of degradation were studied by analysing a variety of parameters such as the behaviour or the EPR signal with the photoexcitation, the process of signal relaxation at different temperatures and the evaluation of the EPR signal of pure organometallic compounds and its dispersion in different polymeric matrices. The results showed that a relatively low EPR signal is obtained for pure Flrpic compound. However its insertion in polymeric matrices caused a significant increase in the signal intensity. The optical absorption and emission data have shown that the excited species are initially photogenerated in metal complexes of those compounds, promoting the subsequent formation of paramagnetic centres, close to Indium atom. The energy levels analysis also suggests an exciton trapping process, which were associated with...
Mestre
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Zhang, Youwen, Samuel D. Cross, James B. Stanton, Alan D. Marmorstein, Yun Zheng Le, and Lihua Y. Marmorstein. "Early AMD-like defects in the RPE and retinal degeneration in aged mice with RPE-specific deletion of Atg5 or Atg7." MOLECULAR VISION, 2017. http://hdl.handle.net/10150/623963.
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Purpose: To examine the effects of autophagy deficiency induced by RPE-specific deletion of Atg5 or Atg7 in mice as a function of age. Methods: Conditional knockout mice with a floxed allele of Atg5 or Atg7 were crossed with inducible VMD2-rtTA/Cre transgenic mice. VMD2-directed RPE-specific Cre recombinase expression was induced with doxycycline feeding in the resulting mice. Cre-mediated deletion of floxed Atg5 or Atg7 resulted in RPE-specific inactivation of the Atg5 or Atg7 gene. Plastic and thin retinal sections were analyzed with light and electron microscopy for histological changes. Photoreceptor outer segment (POS) thickness in plastic sections was measured using the Adobe Photoshop CS4 extended ruler tool. Autophagic adaptor p62/SQSTM1 and markers for oxidatively damaged lipids, proteins, and DNA were examined with immunofluorescence staining of cryosections. Fluorescence signals were quantified using Image J software. Results: Accumulation of p62/SQSTM1 reflecting autophagy deficiency was observed in the RPE of the Atg5(Delta RPE) and Atg7(Delta RP)E mice. 3-nitrotyrosine, advanced glycation end products (AGEs), and 8-hydroxy-2'-deoxyguanosine (8-OHdG), markers for oxidatively damaged proteins and DNA, were also found to accumulate in the RPE of these mice. We observed retinal degeneration in 35% of the Atg5(Delta RPE) mice and 45% of the Atg7.RPE mice at 8 to 24 months old. Degeneration severity and the number of mice with degeneration increased with age. The mean POS thickness of these mice was 25 mu m at 8-12 months, 15 mu m at 13-18 months, and 3 mu m at 19-24 months, compared to 35 mu m, 30 mu m, and 24 aem in the wildtype mice, respectively. Early age-related macular degeneration (AMD)-like RPE defects were found in all the Atg5(Delta RPE) and Atg7.RPE mice 13 months old or older, including vacuoles, uneven RPE thickness, diminished basal infoldings, RPE hypertrophy/hypotrophy, pigmentary irregularities, and necrosis. The severity of the RPE defects increased with age and in the mice with retinal degeneration. RPE atrophy and choroidal neovascularization (CNV) were occasionally observed in the Atg5(Delta RPE) and Atg7(Delta RPE) mice with advanced age. Conclusions: Autophagy deficiency induced by RPE-specific deletion of Atg5 or Atg7 predisposes but does not necessarily drive the development of AMD-like phenotypes or retinal degeneration.
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Gao, Jiangyuan. "NLRP3 inflammasome activity in RPE : role in AMD pathogenesis." Thesis, University of British Columbia, 2017. http://hdl.handle.net/2429/62512.
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Purpose:
Age-related macular degeneration (AMD) is a devastating eye disease causing irreversible vision loss in the elderly. Retinal pigment epithelium (RPE), an important cell type afflicted in AMD, undergoes cell death in the late stages of the disease. Salient factors underlying AMD pathogenesis are aging, drusen components and NLRP3 inflammasome activity. The purpose of this dissertation is to elucidate the molecular interactions among these factors and how they contribute to RPE damage.
Methods:
The effects of aging on drusen components, in particular the membrane attack complex (MAC) and amyloid beta (Aβ) were examined in rats at different age. To determine the role of MAC in inflammasome activation in RPE, aurin tricarboxylic acid complex (ATAC), was administrated to naïve rats. To understand Aβ’s role in inflammasome activation, Aβ intravitreal injections were made into rat eyes in vivo and Vinpocetine was used to ameliorate the inflammatory responses. An in vitro RPE cell culture model was established to further investigate the relationship between inflammasome and X-chromosome linked inhibitor of apoptosis (XIAP). Statistical significance was set at p ≤ 0.05.
Results:
An age-dependent increase in MAC, Aβ, and NF-κB activation was observed in the RPE-choroid in vivo. Blocking MAC formation with ATAC led to a prominent reduction in inflammasome activity (caspase-1 cleavage and cytokine secretion), but not in NF-κB activity. Aβ intravitreal injections triggered inflammasome activation evidenced by enhanced caspase-1 cleavage and IL-1β/IL-18 release, which was suppressed by Vinpocetine mediated NF-κB inhibition. The robust inflammasome activity further led to gasdermin D-mediated activation of the pyroptotic pathway and a significant reduction in XIAP, which in turn enhanced IL-18 secretion.
Conclusion:
Aging is a strong risk factor for AMD, which increases the deposition of MAC and Aβ in the outer retina. The elevated levels of MAC and Aβ are triggers for inflammasome activation. By demonstrating a causal relationship between inflammasome activation and XIAP reduction, this dissertation suggests the precise regulation of XIAP, together with the suppression of MAC and NF-κB, may be crucial for controlling inflammasome activity and hence provides new avenues to prevent AMD.Medicine, Faculty of
Graduate
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Moraes, Itamar Jose. "RPE dos íons Cr3+, Er3+ e Mn2+ em Ca3Ga2Ge3O12." Universidade de São Paulo, 1993. http://www.teses.usp.br/teses/disponiveis/54/54132/tde-08122014-162605/.
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O objetivo principal deste trabalho é o estudo por ressonância paramagnética eletrônica das impurezas Cr3+, Er3+ e Mn3+ no monocristal Ca3Ga2Ge3O12 (denominado CGGG) nas freqüências de 1.3, 10 e 34 GHz e nas temperaturas de 4,2K a 300K. O Hamiltoniano de spin para o Cr3+ alojado no sítio octaédrico com simetria C Cr3i é dado por: H = β[g⊥ (HxSx + HySy) + gHzSz] + D (S2z - 1/3 S (S+1). Os parâmetros do Hamiltoniano de spin para o íon Cr3+ em baixas concentrações são: g = 1,9727 ± 0,0003, g⊥ = 1,9617 ± 0,0008 e D = 16,20 ± 0,02GHz para CGGG dopados com o íon Cr3+. Os cristais CGGG, dopados com Er3+ e Cr3+, apresentaram os seguintes parâmetros g = 1,9662 ± 0,0003, g⊥ = 1,9617 ± 0,0008 e D = 15,82 ± 0,02GHz. Os parâmetros do Hamiltoniano de spin efetivo para o íon Er3+ alojado no sítio dodecaédrico e com simetria D2 são: gx = 2,690 ± 0,0005, gy = 4,095 ± 0,005 e gz = 5,082 ± 0,005. Os centros paramagnéticos Mn2+ produzidos em cristais dopados com Cr3+, irradiados com raios X, à temperatura ambiente, apresentam o fator-g isotrópico, g = 2,0066 ± 0,0001 e a constante de interação hiperfina A = 90 Gauss. Medimos, também as dependências das larguras de linhas com a temperatura, nas três bandas e para banda X medimos nas temperaturas de 4,2K até 300KIn this work was studied the Electron Paramagnetic Resonance (RPE) of the impurities Cr3+, Er3+ and Mn3+ in Ca3Ga2Ge3O12 single crystals (Known as CGGG) at frequencies of 1.3, 10 and 34 GHz in the temperatures range 4,2K to 300K. Spin Hamiltonian for the Cr3+ íons, located at octahedric position with symetry Cr3i is given by: H = β[g⊥ (HxSx + HySy) + gHzSz] + D (S2z - 1/3 S (S+1). The relevant parameters for CGGG lightly dopped with Cr3+ as determined from the EPR spectra are: g = 1,9662 ± 0,0003, g⊥ = 1,9617 ± 0,0008 and D = 15,82 ± 0,02GHz. CGGG crystals simultaneously dopped with Er3+ and Cr3+ shown the following parameters: g = 1,9662 ± 0,0003, g⊥ = 1,9617 ± 0,0008 e D = 15,82 ± 0,02GHz. Effective spin Hamiltonian parameters for Er3+ íon, located at dodecahedric position and with symetry D2, are: gx = 2,690 ± 0,0005, gy = 4,095 ± 0,005 e gz = 5,082 ± 0,005. Paramagnetic centers Mn2+ produced in Cr3+ dopped crystals, X-ray irradiated, at room temperature, shown the isotropic g-factor g = 2,0066 ± 0,0001 and the hyperfine interaction constant A = 90 Gauss. Also, was measured the temperature dependence of the line width in the three frequency bands, in the range of liquid nitrogen to room temperature. In the case of the X-band, the measurements were extended to lower temperatures, 4.2K to 300K
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Schüle, Georg. "Mechanismen und On-line Dosimetrie bei selektiver RPE Therapie /." Berlin : Dissertation.de, 2003. http://bvbr.bib-bvb.de:8991/F?func=service&doc_library=BVB01&doc_number=010295155&line_number=0001&func_code=DB_RECORDS&service_type=MEDIA.
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Santana, Ricardo Costa de. "RPE do ion Fe3+ em monocristais e fibras de LiNbO3." Universidade de São Paulo, 1994. http://www.teses.usp.br/teses/disponiveis/76/76132/tde-09042008-084147/.
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O objetivo deste trabalho foi o estudo do íon Fe3+ em monocristais e fibras monocristalinas de LiNbO3, através da técnica espectroscópica da Ressonância Paramagnética Eletrônica (RPE), nas freqüências de 10 e 34GHz, à temperatura ambiente. O Hamiltoniano de Spin para o íon Fe3+ ocupando um sítio de simetria trigonal (C3v) é dado por: H = \'beta\' \'VET.H\' \'VET.g\' \'VET.S\' + \'B20O20+B40O40 . Foram analisadas três amostras de LiNbO3, com diferentes concentrações de Fe3+ e os parâmetros de campo cristalino e fator-g encontrados são: fibra (0.3 mol% de Fe3+) g = 1.9908 \'+OU-\' 0.0002, \'B. SUP. 0 INF. 2\' = 5.4\'+OU-\'0.2x10-2 cm-1 , \'B. SUP. 0 INF. 4\' = -7.7\'+OU-\'1.5x10-5cm-1, monocristal 90 (0.22 mol%) g = 2.0043\'+OU-\'0.0002, \'B. SUP. 0 INF. 2\' = 5.35\'+OU-\'0.25x10-2 cm-1, \'B. SUP. 0 INF. 4\'= - 4.03\'+OU-\'1.4x10-5cm-1, monocristal 99 (0.02 mol%) g = 2.0026\'+OU-\'0.0004, \'B. SUP. 0 INF. 2\' = 5.4\'+OU-\'0.3x10-2 cm-1, \'B. SUP. 0 INF. 4\' = - 8.33\'+OU-\'1.6x10-5cm-1. Foi medida e analisada a dependência angular da largura das linhas nas duas bandas de freqüências. Através de modelos teóricos (Watanabe, Orbach-Das-Sharma, Spinspin, Spin-spin Spin-órbita) calculamos o parâmetro de desdobramento a campo zero, \'B. SUP. 0 INF. 2\', do estado fundamental do íon Fe3+, para determinar qual o sítio que este íon ocupa no LiNbO3.We report EPR measurements of Fe3+ ion in bulk LiNbO3 single crystals and in the form of fibers. Spin Hamiltonian for the Fe3+ ion in a trigonal symmetry (C3v) site is given by: H = \'beta\' \'VET.H\' \'VET.g\' \'VET.S\' + \'B20O20+B40O40. Measurements were performed at room temperature and two frequency bands, 10 and 34GHz, using three samples of LiNbO3 with different concentrations of Fe3+ g-factor and the crystal field parameters were found to be: for fiber (0.3 mol% of Fe3+) g = 1.9908 \'+OU-\' 0.0002, \'B. SUP. 0 INF. 2\' = 5.4\'+OU-\'0.2x10-2 cm-1 , \'B. SUP. 0 INF. 4\' = -7.7\'+OU-\'1.5x10-5cm-1, for the single crystal 90 (0.22 mol%) g = 2.0043\'+OU-\'0.0002, \'B. SUP. 0 INF. 2\' = 5.35\'+OU \'0.25x10-2 cm-1, \'B. SUP. 0 INF. 4\'= - 4.03\'+OU-\'1.4x10-5 cm-1, and for the single crystal 99 (0.02 mol%) g = 2.0026\'+OU-\'0.0004, \'B. SUP. 0 INF. 2\' = 5.4\'+OU-\'0.3x10-2 cm-1, \'B. SUP. 0 INF. 4\' = - 8.33\'+OU-\'1.6x10-5cm-1. The angular dependence of the line width were also measured and compared with theoretical model. To determine the substitutional site of Fe3+ ion in the LiNbO3 lattice, we calculated the zero field splitting parameter \'B. SUP. 0 INF. 2\' of the ground state, using many theoretical models (Watanabe, Orbach-Das-Sharma, Spin-spin, Spin-Spin Spinorbita).
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Barbosa-Sabanero, Karla Y. "Dedifferentiation and transdifferentiation: a study of the RPE cell identity." Miami University / OhioLINK, 2016. http://rave.ohiolink.edu/etdc/view?acc_num=miami1468660645.
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Lu, Tianlin. "Studies on the Mechanism behind Retinal Pigment Epithelium (RPE) Reprogramming." Miami University / OhioLINK, 2019. http://rave.ohiolink.edu/etdc/view?acc_num=miami1575301308695243.
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Michel, Philippe. "Synthèse et étude de matériaux organiques à raie RPE étroite." Paris 11, 1989. http://www.theses.fr/1989PA112013.
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Les sels de radicaux cations de polyaromatiques présentent des propriétés RPE interressantes ainsi le matériau(fluoranthene) 2PF6 possède une largeur de raie RPE de 10 MG. L'intabilité thermique de ces colides constitue un obstacle a leur utilisaton industrielle. Nous avons supposé que l'instabilité des matériaux était due au potentiel d'oxydation trop élevé des substrats utilisés. Nous avons cherché à l'abaisser en substituant les molécules organiques. Cette substitution ayant également pour effet de modifier la dimensionnalité des matériaux nous avons préparé deux pérylènes substitués par une voie de synthèse originale. L'un d'entre eux a conduit à un sel de radical -cation, présentant une faible larguer de raie RPE (16 MG) et une bonne stabilité thermique. Nous avons cherché à l'expliciter les différents facteurs qui seraient responsables, du rétrécissement dela raie. Ainsi nous avons préparé et étudié le sel de radiacl-cation connu de stchiométrie 2:1 du pérylène lui-même et celui du 1,2,7,8-Tetrahydro-CD LM-Dicyclopentaperylene. La comparaison des données structurales à permis de mettre en évidence l'effet de la dimensionnalité sur la largeur de raie. Il semble ainsi possible d'obtenir des matériaux à raies encoire plus étroites en substituant convenablement les substrats adéquatsRadical-cation salts derived from polyaromatic donors exhibit very interesting EPR properties. Thus, the linewidth of the material (fluo19 ranthene) 2PF6 is only 10 mG. However, the high thermal instability of these solids has so far precluded industrial applications. Our goal was to obtain stable materials with a narrow EPR line. We assumed that the high oxydation potentials of the substrates was one of the reasons of the instability. We have tried to lower these potentials by an adequate substitution of the aromatic molecules, the effect of this substitution being also to modify dimensionnality of the materials, a factor which would predictibly affect the linewidth. We have prepared two substituted perylenes, using an original synthesis. One of the them, the 3,4,9,10-tetramethylperylene, led to a radicalcation salt, with a 2:1 stoechiometry. The linewidth of this material is 16 mG, its thermal stability is very good up to 80°C. We then attempted to investigate the factors which might be responsible of the narrowing of the line, in this series deriving from perylene. Therefore, we prepared and studied the 2:1 radical-cation salts of perylene itself. We prepared also the 2:1 salt deriving from 1,2,7,8 -tetrahydro [cd;1m]dicyclopentaperylene, which had already been described. The comparison of the structural data allowed us to show unambiguously the beneficial effect of the dimensionnality on the linewidth. It seems possible, adopting the same approach we used for perylene, to obtain materials with still narrower EPR lines by adequatly substituting the suitable substraces. The communication of the contents of this thesis is submitted to the authorization of the Thomson-Sintra ASM company
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Gambarelli, Serge. "Etude des proprietes magnetiques et des spectres rpe de biradicaux nitroxydes." Paris 6, 1996. http://www.theses.fr/1996PA066560.
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Cette these traite des proprietes magnetiques variees de biradicaux nitroxydes. Nous etudions tout d'abord en phase solide et en solution trois biradicaux derives du metaxylylene. L'importance de la conformation des molecules sur leur etat fondamental est mis en evidence. Puis, a partir des donnees de la litterature, la nature de la transition de phase magnetique du dupeyredioxyle est discute. Un cryostat est fabrique avec lequel sont faites des mesures de rpe en bande x et a 1,4 k sur des monocristaux orientes. Les spectres obtenus montrent que ce compose est un antiferromagnetique fortement anisotrope. Enfin, deux biradicaux sont etudies par rpe haut champ. Les conformations de ces especes sont determines en solution
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Crouigneau, Pierre. "Etudes spectroscopiques (electroréflexion uv-visible, RPE) et electrochimiques de dérivés viologènes." Poitiers, 1989. http://www.theses.fr/1989POIT2003.
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L'examen critique des nombreux travaux consacres a la conversion de l'energie solaire par les systemes photosynthetiques artificiels montre que le comportement interfacial des relais d'electrons (viologenes) est relativement mal connu. Deux familles de viologenes comprenant respectivement un ou deux groupement bipyridinium ont ete etudiees a l'aide de techniques spectroscopiques (resonance paramagnetique electronique et spectroscopie uv-visible d'electroreflexion) et electrochimiques (voltammetrie) associees. Les radicaux formes in situ a l'interface solide (metal, semi-conducteur) - solution aqueuse ont pu etre detectes et leurs proprietes (taux de recouvrement des electrodes, duree de vie des especes formees, aptitude a la dimerisation,. . . ) elucidees. Ces resultats permettent de selectionner les relais d'electrons les plus performants et de determiner les concentrations conduisant aux meilleurs rendements de conversion de l'energie lumineuse
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Theurel, Laurence. "Synthèse et caractérisation de radicaux organiques stables pour la magnétométrie RPE." Grenoble 1, 1993. http://www.theses.fr/1993GRE10199.
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Notre travail a consiste a synthetiser et caracteriser de nouveaux materiaux radicalaires de trois familles differentes (neutres, cations et anions), pour les applications de la magnetometrie par resonance paramagnetique electronique (rpe). Trois nouvelles phtalocyanines de lithium octa-substituees ont ete preparees. Les etudes rpe ont montre que ces composes ne possedent pas d'avenir pour nos applications. Nous avons prepare deux nouveaux radicaux cations du perylene avec comme anion associe, teof#5# et ((teof#5)h)#. Les bonnes caracteristiques de ce dernier font de lui un candidat a fort potentiel pour la magnetometrie. Plusieurs radicaux tcnq ont ete synthetises et caracterises par rpe. De ces etudes, deux materiaux se sont reveles particulierement interessants pour les applications haute temperature. Une nouvelle classification des radicaux est proposee: les radicaux avec effet d'oxygene et les radicaux avec effet de recuit
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Uzel, Alexandre. "Caractérisation fonctionnelle des formiate-déshydrogénases de Bacillus subtilis par spectroscopie RPE." Electronic Thesis or Diss., Aix-Marseille, 2022. http://theses.univ-amu.fr.lama.univ-amu.fr/220310_UZEL_750yyya237ggtlq644ueoq380vkulm_TH-1.pdf.
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De nos jours un des plus grands défis environnementaux est la bioremediation du CO2 atmosphérique. La réduction biocatalytique de ce dernier en formiate par les formiate déshydrogénases microbiennes (FDHs) apparaît très prometteuse. Dans ce travail est présentée une caractérisation RPE de deux FDHs similaires nommées ForCE 1 et ForCE 2 issues de la bactérie du sol Bacillus subtilis. Elles appartiennent à la superfamille des enzymes à cofacteur de type Mo/W-bisPGD retrouvées exclusivement chez les procaryotes et catalysant une grande variété de réactions chimiques. Ces deux FDHs sont d’un grand intérêt scientifique. Les analyses de leurs séquences révèlent que leur site actif ne présente pas les résidus consensuels associés à l’activité formiate-déshydrogénase, définissant une sous-famille de FDHs encore non caractérisée. Les voies métaboliques dans lesquelles ces FDHs s’intègrent au sein de cet organisme restent à élucider, ouvrant ainsi la voie à d’autres découvertes en biologie.Le coeur catalytique des ForCEs est composé de deux sous-unités. Les analyses de sequences revèlent que la sous-unité catalytique ForC abriterait cinq centres FeS et un cofacteur de type Mo-bisPGD alors que ForE n’apparait pas héberger de cofacteur. En combinant potentiométrie d’oxydoréduction, spectroscopie de résonance paramagnétique électronique (RPE) multifréquence en onde continue et en mode pulsé, nous avons caractérisé les signatures RPE et les propriétés redox de plusieurs centres paramagnétiques dans l’enzyme ForCE1 purifiée, à savoir quatre centres FeS et deux signatures de type Mo(V) associées au cofacteur à molybdène. Un signal radicalaire intense a également été détectéNowadays one of the biggest environmental challenges is the bioremediation of atmospheric CO2. The biocatalytic reduction of CO2 to formate by microbial formate dehydrogenases (FDHs) is very promising. We present the EPR characterization of two similar FDHs, named ForCE 1 and ForCE 2, from the soil bacterium Bacillus subtilis. These enzymes belong to the Mo/W-bisPGD (i.e. pyranopterin guanosine dinucleotide) superfamily, which is widespread in prokaryotes. These two FDHs appear to be of great scientific interest for several reasons : sequence analyses reveal that their active site harbours non-consensual residues for formate-dehydrogenase activity, defining a new FDH sub-familly not yet characterised. Moreover, the way in which these enzymes are integrated into the metabolism of this organism remains to be established, leaving the door open for new biological discoveries. The catalytic core of ForCEs is composed of two subunits. From sequence analysis, the larger one (ForC) is thought to coordinate five iron-sulfur clusters and a Mo-bisPGD while ForE does not appear to harbor any cofactor. By combining redox potentiometry, multifrequency continuous wave (CW) and pulsed EPR spectroscopy, we were able to characterize the EPR signatures and redox properties of several paramagnetic cofactors in the purified enzymes including at least four FeS clusters (the fifth was detected by spin quantitation) and two MoV species associated to the molybdenum cofactor. An unexpectedly intense radical signal was also detected and could be attributed to a highly stabilized menasemiquinone species based on its redox and spectroscopic properties determined by a multi-frequency EPR approach
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Ali, Afaf Mubarak Mohamed. "Accounting for performance : case studies of relative performance evaluation in Egypt and England." Thesis, Sheffield Hallam University, 2000. http://shura.shu.ac.uk/19241/.
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Relative Performance Evaluation "RPE" is a performance evaluation and reward scheme which have been receiving a growing attention from academic and professionals (Holmstrom 1982, Frederickson 1992, Conyon and Gregg 1994, and Defond & Park 1999). Under RPE rewards for managers and executives are set upon their performance compared to that of their peers. Holmstrom (1982) introduced the basic model of RPE founded on agent-principal assumptions. In that model, the peers' performance was seen to provide information about the agent's unobservable effort. Fredrickson (1992) suggested that RPE could satisfy economic and psychological needs of employee. In this study, an attempt is made to depart from the universal agency perspective and to adopt a contingent framework. The research arguments were developed from an identification of the discrepancies and gaps in the literature of RPE, overlooked complications and issues in the UK practice, relating the debate about RPE to the wider accounting literature of performance measurements and evaluation (Emmanuel et.al. 1990, Kaplan & Atkinson 1998). The aim of this research was to explore the content and context of RPE therefore, the arguments focused on: whether RPE is motivating, the impacts of difficulty of peer group, non financial measures, market measures and varying the form of the rewards on RPE. Case study approach was adopted to examine the research arguments. Data were collected from three companies in Egypt and one company in England. Access was partially accidental but turned to provide four different cases. Three cases were developed in Egypt including: Trade (a public company), Dairy (private company) and Steel (joint venture) and the English company was United Utilities (private company). Data were collected by questionnaire, interviews and other documentary sources of the companies. The research findings suggest associations between RPE and target's difficulty, using non financial but not varying rewards. Competition and type of ownership and the organisational culture were influential on RPE.
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Cordes, Magdalena [Verfasser]. "Regulation der Oberflächenexpression von L-Typ-Ca2+-Kanälen im RPE / Magdalena Cordes." Berlin : Freie Universität Berlin, 2019. http://d-nb.info/1196803838/34.
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Armstrong, Ian. "A study of the transport characteristics of mammalian retinal pigment epithelium (RPE)." Thesis, Cardiff University, 1989. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.276870.
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Law, A. L. "The role of annexin 2 in RPE phagocytosis of photoreceptor outer segments." Thesis, University College London (University of London), 2009. http://discovery.ucl.ac.uk/18708/.
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The Retinal Pigmented Epithelium (RPE) has many functions, one of which is the phagocytosis of shed photoreceptor outer segments (POS). This process is vital to the maintenance of both the RPE and photoreceptors. Outer segment shedding and internalisation are under circadian regulation, such that shedding is followed by a burst of phagocytosis at the onset of light. Annexin 2 is well placed to have a role in this process. Its direct involvement in actin dynamics and association to vesicle membranes during endocytosis may be significant in RPE outer segment phagocytosis, as this process requires extensive re-organisation of actin and re-distribution of membrane on the apical processes of the RPE. This thesis examines cell differentiation in two RPE cell lines and in primary porcine RPE cells, in order to evaluate the best system for conducting phagocytosis experiments. In vitro experiments provided evidence that annexin 2 localises to the phagocytic cup during POS internalisation but dissociates once internalisation is complete. Following knock down of annexin 2, phagocytosis was shown to decrease. Furthermore annexin 2 was shown to be phosphorylated during phagocytosis. We also found that c-Src is phosphorylated alongside annexin 2 and therefore may phosphorylate annexin 2, which contains a c-Src phosphorylation site. To investigate the circadian aspects of POS phagocytosis by the RPE, apical and basal phagosomes were quantified in the RPE from annexin 2 knock out and wild type eyes, harvested before and after light onset. Phagosomes from eyes harvested one hour after light onset were also mapped relative to Bruch’s membrane. The annexin 2 knock out animals lack the characteristic burst of phagocytosis one hour after light onset exhibited in wild type animals. Phagosomes were also retarded in the apical processes one hour after light onset, at the peak of phagocytosis, when they are normally internalised into the cell body for processing and degradation. Lysates from wild type eyes showed that annexin 2 is phosphorylated before light onset along with c-Src and FAK, key molecules in the RPE phagocytic machinery. Importantly, the absence of annexin 2 in knock out eyes delayed phosphorylation of c-Src and FAK. This delay in phosphorylation of two key RPE phagocytosis molecules may account for the delay in ingestion of outer segments into the cell body and the accumulation of phagosomes in the apical processes observed in the knock out animals. In conclusion, work in this thesis has demonstrated that annexin 2 is required for efficient RPE internalisation of rod outer segments both in vitro and in vivo. Annexin 2 is required for the timely phosphorylation of FAK and c-Src, which may account for the delay in POS internalisation observed in the annexin 2 knock out mice.
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Bakker, Linda Margaretha. "Peroxidized docosahexaenoic acid causes RPE dysfunction : implications for retinal ageing and AMD." Thesis, Cardiff University, 2008. http://orca.cf.ac.uk/54734/.
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The aim of this study was to gain important insights into the effects of peroxidized docosahexaenoic acid (pDHA) on the retinal pigment epithelium (RPE), and whether its effects can cause RPE cell dysfunction in a way similar to that observed in retinal ageing and the pathogenesis of age-related macular degeneration (AMD). Initially, the time-course of in vitro peroxidation of DHA was monitored, culminating in formation of products able to absorb light above 400 nm. Cultured RPE cells were then exposed to this pDHA, which was shown to be toxic, both in dark and light-exposed conditions. Various cell viability assays were carried out indicating RPE cell death after exposure to pDHA is likely to occur by apoptosis. The effects of pDHA were reduced in the presence of various agents - a-tocopherol, glutathione, N-acetylcysteine, and phosphatidylethanolamine (PE). Measurements of singlet oxygen, transient and superoxide production were carried out to determine the photosensitizing properties of pDHA. The ability of PE to reduce the production of these species was investigated but it was shown to have no effect on their yield, although singlet oxygen lifetime was reduced. Finally, lysosomal enzyme activity, lysosomal integrity and accumulation of fluorescent and undegraded material were monitored after exposure to pDHA, demonstrating that pDHA was able to disrupt the ability of the RPE to fully degrade phagocytosed material. In summary, pDHA is able to affect RPE cell viability directly when exposed extracellularly, and can also affect essential normal functions of the RPE intracellularly. In conjunction with published findings that pDHA is present in the retina - both within and around the RPE - the data presented here support the theory that pDHA can play an important role in causing RPE dysfunction, resulting in a loss of the protective role these cells play for photoreceptors, as occurs in retinal ageing and AMD.
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Brasil, Filho Nilson. "Ressonância magnética eletrônica (RPE) e nuclear (RMN) em compostos e hidretos metálicos." [s.n.], 1985. http://repositorio.unicamp.br/jspui/handle/REPOSIP/278166.
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Orientador: Jose Suassuna FilhoDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
Made available in DSpace on 2018-07-17T03:32:32Z (GMT). No. of bitstreams: 1 BrasilFilho_Nilson_M.pdf: 2125274 bytes, checksum: fd2f77e8149f9df15d3ca21677423de5 (MD5) Previous issue date: 1985
Resumo: Foram realizadas medidas de RMN pulsadas nos hidretos metálicos ZrCr2Hx (x = 2, 3 e 4) e ZrV2Hy (y = 2, 3, 4 e 5) no intervalo de temperatura entre 180K e 400K. Nosso objetivo foi investigar os mecanismos de relaxação nesses hidretos através de medidas dos tempos de relaxação spin-rede (T1) e spin-spin (T2) para o hidrogênio, e obter informações com respeito aos mecanismos de difusão do hidrogênio na rede metálica. Foram obtidas as energias de ativação, as freqüências de salto e a constante Ck, relacionada com a relaxação spin-elétron de condução, para o hidrogênio nos hidretos acima citados. Nossos resultados foram analisados à luz das teorias de relaxação modulada por interação dipolar (modelos de BPP e de Torrey) e da relaxação tipo Korringa (devida aos elétrons de condução) em sistemas metálicos. Na segunda parte desta tese, foram medidos o deslocamento do fator-g e a razão de Korringa nas linhas de RPE dos íons Gd3+, Nd3+ e Er3+ diluídos em compostos intermetálicos AB3 (A = La, Ce, Y, Sc, Th, Zr; B = Rh, Ir, Pt) de estrutura tipo AuCu3. Os resultados de RPE nestas séries de compostos foram analisados em termos do modelo de multibandas em metais, proposto anteriormente por Barberis e outros (1979) para explicar o comportamento dos parâmetros de Ressonância em compostos intermetálicos do tipo fase de Laves AB2
Abstract: Proton pulsed Nuclear Magnetic Resonance measurements were performed on the metallic hydridesZrCr2Hx (x = 2, 3, 4) and ZrV2Hy (y = 2, 3, 4, 5) as a function of temperature between 180 and 400 K. The ultimate aim was the investigation of the relaxation mechanisms in these systems by means of the measurement of both the proton (1H) spin-lattice (T1) and spin-spin (T2) relaxation times and to use these data to obtain information about the diffusive motion of the hydrogen atoms. The diffusional activation energies, the jump frequencies and the Korringa constant, Ck, related with the conduction electron contribution to the 1H relaxation were determined for the above hydrides as a function of hydrogen concentration. Our results were analyzed in terms of the relaxation models described by Bloembergen, Purcell and Pound (BPP models) and by Torrey. The Korringa type relaxation due to conduction electrons in metallic systems was also used to interpret the experimental results. We also present the Electron Paramagnetic Resonance (EPR) study of Gd3+, Nd3+ and Er3+ ions a impurities in several AB3 intermetallic compounds were A = La, Ce, Y, Sc, Th, Zr and B = Rh, Ir, Pt. The results were analyzed in terms of the multband model previously suggested to explain in the behavior of the resonance parameter in AB2 Laves Phase compound
Mestrado
Física
Mestre em Física
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Goze-Bac, Christophe. "Contribution à l'étude du fullerène C60 et dérivés : études RMN et RPE." Montpellier 2, 1996. http://www.theses.fr/1996MON20047.
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Le but poursuivi dans ce travail est l'analyse des proprietes physiques de certains derives du fullerene c60. A l'aide des techniques rmn et rpe, nous avons etudie les composes axc60 avec a=k, rb, cs et x=1, 3, 4 et 6 dont nous avons assure la preparation. Nous avons etudie aussi les polymeres orthorombique 1d et rhomboedrique 2d obtenus sous haute pression et temperature. Nos resultats ont apporte des elements essentiels a la comprehension de ces nouveaux materiaux. Nous avons apporte la confirmation de la liaison de cycloaddition entre molecule c60 dans les phases polymeres. Nous avons determine l'origine de la resonance inattendue t' dans le spectre rmn de l'alcalin du compose rb3c60 et propose un modele base sur la diffusion de sites tetraedriques vacants. Nous avons explique le caractere isolant de la phase 4 a l'aide d'un modele base sur l'effet jahn-teller moleculaire. Dans la phase saturee, nous avons confirme l'ordre orientationnel des molecules de c60 et la presence de carbones inequivalents prevus par les etudes structurales
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Ouajahat, Filali Aziz. "Evaluation de la photoréactivité des quinolones antibactériennes par photo-CIDNP et RPE." Lille 1, 1987. http://www.theses.fr/1987LIL10034.
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FEAUGAS, VALERIE. "Caracterisation des facteurs influant sur l'evolution du signal rpe de l'alanine irradiee." Paris 11, 1999. http://www.theses.fr/1999PA112310.
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La dosimetrie par resonance paramagnetique electronique (rpe) de l'alanine est basee sur la mesure du signal rpe des radicaux libres, induits dans l'alanine par irradiation. L'objectif de cette these etait de caracteriser les facteurs influant sur l'evolution de l'amplitude du signal rpe de l'alanine irradiee afin de limiter l'incertitude sur la determination de la dose absorbee. La premiere etape de ce travail a ete le choix de l'isomere d'alanine et de la forme physique du dosimetre. Une etude bibliographique completee par des experiences sur la reponse des isomeres de l'alanine a la dose et sur sa stabilite dans le temps, nous a conduit a choisir comme dosimetre la l--alanine sous forme pulverulente. L'influence des parametres de reglage du spectrometre sur les caracteristiques du spectre rpe a ensuite ete etudiee. Ceci nous a permis d'optimiser les conditions d'enregistrement des spectres rpe. L'anisotropie angulaire du signal rpe de l'alanine limitant la reproductibilite des mesures, un protocole experimental a ete defini de facon a pallier cet effet. La repetabilite des mesures a ete amelioree en modifiant le spectrometre et en utilisant une reference interne constituee de monocristaux de cuso 4. 5h 2o. L'amplitude du signal rpe etant sensible a la temperature de lecture, une methode de normalisation des resultats a 20\c a ete mise au point. Nous nous sommes interesses a l'influence d'un parametre d'irradiation et de parametres environnementaux sur l'amplitude du signal rpe de l'alanine irradiee. Nous avons montre que l'amplitude augmente avec la temperature d'irradiation. D'autre part, l'amplitude et sa stabilite au cours du temps sont fortement influencees par la teneur en eau des echantillons. Une forte teneur en eau a un effet nefaste mais en partie reversible sur l'amplitude du signal. L'exposition des dosimetres a la lumiere a egalement pour consequence la diminution de l'amplitude du signal. Par contre, l'oxygene n'influence pas le spectre rpe de l'alanine. Nous avons remarque que l'amplitude du signal rpe d'echantillons stockes en dessicateur avant et apres irradiation augmente d'environ 5% dans la dizaine de jours suivant l'irradiation. Ce phenomene est tres vraisemblablement lie a la poursuite de reactions radicalaires dans l'alanine apres irradiation.
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Robert, Jérôme, and J. J. ANDRE. "Magnetisme des fullerenes intercales : etude par rpe en ondes continue et pulsee." Université Louis Pasteur (Strasbourg) (1971-2008), 1995. http://www.theses.fr/1995STR13151.
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Le but de cette these est l'etude par resonance paramagnetique electronique (rpe) en onde continue et pulsee des composes d'intercalation du fullerene. Dans l'etat normal, la susceptibilite rpe des composes supraconducteurs k3c60 et rb3c60 permet de calculer la densite d'etats au niveau fermi. L'etude de sa variation thermique, associee a la contraction thermique du reseau permet de determiner certains parametres de l'etat supraconducteur dans le cadre de la theorie bcs, comme l'energie caracteristique des phonons, le couplage electron-phonon et la repulsion coulombienne. L'absence des composes k1c60 et rb1c60 dans le premier diagramme de phase est du a leur detection difficile sur les cliches de diffraction des rayons x et a leur instabilite a temperature ambiante. Suivant le traitement thermique, ils se presentent sous trois phases: une phase stable cubique faces centrees haute temperature, une phase polymere orthorhombique (o. P) stable avec le rubidium et metastable avec le potassium en dessous de 350 kelvin et une phase metastable dimere quasi-orthorhombique (o. D) obtenue par trempe de la phase cfc. Chaque phase presente ses propres caracteristiques rpe, ce qui nous permet de circonscrire les regions de stabilite thermique et d'identifier les transformations de phase. Une etude cinetique en fonction de la temperature quantifie l'energie impliquee dans ces transformations de phases. Les experiences de rpe a impulsions confirment le caractere metallique du polymere rb1c60. Enfin, nous interpretons la transition metal-isolant que subit ce compose a basse temperature. Au dela des proprietes isolantes commune des composes k4c60, na2c60 et na9. 8c60. Nous constatons que la variation en fonction de la temperature de la susceptibilite rpe traduit un equilibre singulet fondamental-triplet, dont l'ecart est lui-meme variable avec la temperature pour les deux premiers composes. Le role des modes de phonons intramoleculaires est invoque pour expliquer ce phenomene
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Van, Wichelen Koen. "Etude d'un magnétomètre vectoriel différentiel RPE pour application en puits de forage." Université Joseph Fourier (Grenoble), 1995. http://www.theses.fr/1995GRE10244.
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Un magnetometre rpe pour application en puits de forage a ete etudie. La mesure est de type vectoriel et differentiel. Grace aux developpements recents concernant les materiaux radicalaires pour la magnetometrie rpe, la technologie choisie offre des perspectives par rapport a l'etat de l'art (technologie flux-gate) pour un fonctionnement jusqu'a des temperatures de 200c environ. Un prototype d'outil de diagraphie operationnel a frequence de resonance de 70 mhz a ete developpe pour valider l'architecture du magnetometre. Des mesures avec cet outil de diagraphie ont ete effectuees dans quelques puits de forage afin de valider sa mise en uvre (evaluation des performances en milieu reel d'application, epreuve de reproductibilite). Les performances du magnetometre rpe sont analysees aussi par comparaison avec un instrument vectoriel et differentiel utilisant la technolotie flux-gate
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Lane, Brandon. "Otx but not Mitf transcription factors are required for zebrafish RPE development." VCU Scholars Compass, 2012. http://scholarscompass.vcu.edu/etd/2839.
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Mitf and Otx transcription factors have been identified as essential to the development of the retinal pigmented epithelium (RPE), but the relationship between these factors and their specific role in the RPE developmental pathway have not been clearly defined. The role of the two Mitf transcription factors (Mitfa and Mitfb) and two Otx transcription factors (Otx1a and Otx2) in zebrafish RPE development was explored in these experiments. The loss of Mitf activity in mitfa, mitfb, or double mitf null mutant fish lines had no effect on RPE pigmentation or development. The loss of Otx2 activity through morpholino knockdown produced a RPE deficient phenotype in a small percentage of embryos, while the additional knockdown of Otx1a caused widespread and severe RPE developmental abnormalities. Analysis of ocular sections revealed that the retinal layers remain unaffected in mitf mutants, as well as in most RPE-deficient otx morphants. Mitf and Otx combined loss of function experiments suggest that Mitfa and Mitfb may still play a role in zebrafish RPE development. Expression analysis through in situ hybridization has demonstrated that Otx transcription factors are necessary for the proper expression of mitfa and mitfb while Mitf transcriptions factors are not required for the expression of otx genes. The transcriptional regulation of Mitf by Otx transcription factors may explain why only Otx transcription factors are necessary for zebrafish RPE development despite the somewhat overlapping functions of Mitf and Otx transcription factors.
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Spencer, Samantha A. "The Role of tfec in Zebrafish Neural Crest Cell and RPE Development." VCU Scholars Compass, 2015. http://scholarscompass.vcu.edu/etd/3754.
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Zebrafish (Danio rerio) show a unique pigmentation pattern comprised of three pigment cell types: melanophores, iridophores and xanthophores. Other pigmented cells include the retinal pigmented epithelium (rpe) which absorbs excess light in the eye and maintain the extracellular environment around the photoreceptors. While previous mutations in mitfa showed a role in regulating trunk melanophores, the rpe was not affected. TALENs and CRISPR-Cas9 systems were used to generate mutant zebrafish for tfec, a transcription factor expressed in both neural crest and rpe. Embryos with tfec mutations showed a loss of iridophore pigmentation, and delays in the pigmentation of xanthophores and rpe, showing positive regulation of multiple pigment cells. Double mutants for tfec and mitfa displayed greater losses of iridophore, xanthophore and rpe pigmentation with noncircular globes, suggesting cooperative roles for these transcription factors.
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Ouajahat, Filali Aziz. "Evaluation de la photoréactivité des quinolones antibactériennes par photo-CIDNP et RPE." Grenoble 2 : ANRT, 1987. http://catalogue.bnf.fr/ark:/12148/cb376085778.
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Piccinato, Marilene Turini. "Caracterização de vanadila (VO2+) em petróleo através de ressonância paramagnética eletrônica (RPE)." Universidade Estadual de Londrina. Centro de Ciências Exatas. Programa de Pós-Graduação em Física, 2005. http://www.bibliotecadigital.uel.br/document/?code=vtls000114955.
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Foram analisadas, através da técnica de Ressonância Paramagnética Eletrônica (RPE), amostras de petróleo provenientes dos seguintes países: Argentina (AR), Arábia Saudita (AS), Colômbia (CO), Kuwait (KW), Venezuela (VE) e Brasil. Neste último nos campos
petrolíferos da Bahia (BA), Bacia de Campos (BC), Marlim (B1), Albacora (B2), Cabiúnas (B3), Espadarte (B4), Roncador (B5) e mais três misturas (M1, M2 e M3) utilizadas no Brasil para a produção de derivados. Dentre as espécies paramagnéticas detectadas nos óleos, foram calculados os parâmetros da Hamiltoniana de Spin da vanadila (VO2+): o fator espectroscópico anisotrópico ou fator g e o desdobramento hiperfino. Os valores do chemical shift {Ag0 = (2,003 = g0) x 10 3} 0 0 10 0023 , 2 × - = . g g }, correspondente ao sinal de VO2+ nos óleos da AR, SA, CO, KW, VE, BC, M1, M2, B1, B2, B4 e B5 que estão entre 0 , 25 0 = .g e 0 , 26 0 = .g , sugerem complexos de vanádio do tipo: VO(N2OS), VO(S2O2) ou VO(N3O), enquanto que nos óleos M3 e B3 o valor de 0 27 0 , g = . é característico de complexos de vanádio do tipo VO(S2O2) ou VO(NSO2). As variações nos valores determinados para o parâmetro de interação hiperfina ( 0 A ) do sinal de RPE de VO2+ nos óleos foram muito pequenas (~1%), caracterizando a semelhança da vizinhança química que se encontra o íon paramagnético VO2+. A intensidade relativa do sinal de VO2+ revelou que, o petróleo da Bahia (BA) possui a menor quantidade de íons VO2+, enquanto que o petróleo da Argentina (AR) possui ~87,3 vezes mais íons vanadila.The samples were analyzed, by the technique of Electron Paramagnetic Resonance (EPR), starting from petroleum of the following countries: Argentina (AR), Saudi Arabia (SA), Colombia (CO), Kuwait (KW), Venezuela (VE) and Brazil. In this last one in the oil fields of Bahia (BA), Basin of Campos (BC), Marlim (B1), Albacora (B2), Cabiúnas (B3), Espadarte (B4), Roncador (B5) and three mixtures (M1, M2 and M3) be used in Brazil for the production of oil derivatives. Amongst paramagnetic species detected in oils by EPR were calculated Spin Hamiltonian parameters of vanadyl (VO2+): anisotropy spectroscopic factor or g-factor and unfolding hyperfine. The value of chemical shift {Ag0 = (2,003 = g0) x 10 3}0 0 10 g 0023 . 2 g × - = . } corresponding to the VO2+ signal in the oils AR, SA, CO, KW, VE, BC, M1, M2, B1, B2, B4 and B5 that are between 0 25 0 . g = . and 0 26 0 . g = . , suggests vanadium complexes of the type VO(N2OS), VO(S2O2) or VO(N3O), while which in M3 and B3 oils, the value of 0 . 27 0 = .g it is characteristic of vanadium complexes of type VO(S2O2) or VO(NSO2). The variations found in the hyperfine interaction parameter ( 0 A ) of the VO2+ EPR signal in petroleum were small (~1%), demonstrating the similarity in the chemical environment of the paramagnetic ion VO2+. The relative intensity of the VO2+ signal revealed that Bahia's Petroleum (BA) has the smallest quantity of ions VO2+, while Argentina's Petroleum (AR) has ~87.3 larger ions vanadyl.
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Nogueira, Roberto Alves. "Aquisição de dados em experiências de RPE usando minicomputador de tempo real." Universidade Federal de Minas Gerais, 1990. http://hdl.handle.net/1843/BUOS-97WF8D.
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In this work we developed two real-time acquisition computer systems, for data acquisition in Electron Paramagnetic Ressonance Experiments. In both, a high degree of freedom was kept in the measuring instruments configuration and progrtamming, whiti the sim of making easy a future reassignment to other experimental technics to be installed in the laboratory. One of the systems is an improves version of the so called Passive Monitoribs System and was built in such a way that it can be used in conjunction with the normal operation mode of the spectrometer. The other system incorporates, in addition to the data acquisition facilities, an step motor based gear to drive the sweep of the magnetic field. Furthermore, a large program was also developed to facilitate the processing of the spectra and their transportation to other computers.
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Doe, Vicki Haywood. "Effect of Cardiac Rehabilitation in Depressed Versus Nondepressed Individuals on Fitness, Depression, and Perceived Exertion." Kent State University / OhioLINK, 2009. http://rave.ohiolink.edu/etdc/view?acc_num=kent1258921420.
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Yu, Jie. "Classification of Genotype and Age of Eyes Using RPE Cell Size and Shape." Digital Archive @ GSU, 2012. http://digitalarchive.gsu.edu/math_theses/118.
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Retinal pigment epithelium (RPE) is a principal site of pathogenesis in age-related macular de-generation (AMD). AMD is a main source of vision loss even blindness in the elderly and there is no effective treatment right now. Our aim is to describe the relationship between the morphology of RPE cells and the age and genotype of the eyes. We use principal component analysis (PCA) or functional principal component method (FPCA), support vector machine (SVM), and random forest (RF) methods to analyze the morphological data of RPE cells in mouse eyes to classify their age and genotype. Our analyses show that amongst all morphometric measures of RPE cells, cell shape measurements (eccentricity and solidity) are good for classification. But combination of cell shape and size (perimeter) provide best classification.
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McFarlane, S. "An investigation of the effect of advanced glycation on age-related RPE dysfunction." Thesis, Queen's University Belfast, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.268450.
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CATTANI, MARTA M. "Estudo por ressonancia paramagnetica eletronica (RPE) em graos e farinacios irradiados com sup60Co." reponame:Repositório Institucional do IPEN, 1995. http://repositorio.ipen.br:8080/xmlui/handle/123456789/10427.
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Dissertacao (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP
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Clément, Jean-Louis. "Synthèse et études RPE dans la série des pyrrolines n-oxyde b-phosphorées." Aix-Marseille 3, 1998. http://www.theses.fr/1998AIX30096.
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La 2-diethylphosphono-2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (depmpo) est une nitrone -phosphorylee interessante pour le piegeage de radicaux (spin trapping) comme le radical superoxyde. La premiere partie de ce travail est consacree a la preparation d'une nouvelle serie de nitrones -phosphorylees analogues de la depmpo. Nous avons synthetise la 2-diethylphosphono-2-( 2h 3-methyl)-3- 2h 2,4- 2h 2-dihydro-2h-pyrrole 1-oxyde (depmpo d 7), la 2-diethylphosphono-2-( 2h 3-methyl)-3- 2h 2,4-dihydro-2h-pyrrole 1-oxyde (depmpo d 5), la 2-diethylphosphono-2-methyl-3,4- 2h 2-dihydro-2h-pyrrole 1-oxyde (depmpo d 2) une serie de nitrones deuteriees. Nous avons synthetise la 2-di(2,2,2-trifluoroethyl)phosphono-2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (depmpo f 6), la 2-dibenzylphosphoryl-2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (dbzpmpo), la 2-phosphono-2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (dhpmpo) une serie de nitrones avec des groupes phosphores varies. Nous avons synthetise la 2-diethylphosphono-3-hydromethyl-2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (4hm depmpo) une nitrone avec une fonction hydroxymethyle en position 3. Nous avons modifie la lipophilie des nitrones en modifiant la nature des substituants autour de l'atome de phosphore en preparant la 2-diphenylphosphono-2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (dppmpo), la 2-dibenzylphosphono-2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (dbpmpo), la 2-didecylphosphono-2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (ddpmpo) et la 2-dioleylphosphono -2-methyl-3,4-dihydro-2h-pyrrole 1-oxyde (dopmpo). Dans le cadre general de l'etude des conformations des adduits de spin issus de la depmpo nous avons synthetise la 2-diethylphosphono-2-( 1 3c-methyl)-3,4-dihydro-2h-pyrrole 1-oxyde (depmpo 1 3c) une nitrone dont le methyle en position 2 est marque par un carbone 13. Dans la deuxieme partie de ce travail nous avons etudie le piegeage de divers radicaux libres pour chacune de ces nouvelles nitrones. Les spectres rpe de chaque adduit de spin sont analyses et caracterises. Une etude de la geometrie des cycles pyrrolidinoxyle est abordee notamment
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Chevalier, Alain. "Contribution à l'étude par spectroscopie Mössbauer et RPE de la stabilité de l'hémoglobine." Grenoble 2 : ANRT, 1988. http://catalogue.bnf.fr/ark:/12148/cb376126926.
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Jacques, Julien. "Réactivité de la nitrate réductase périplasmique étudiée par spectroscopie RPE et électrochimie directe." Thesis, Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4710/document.
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La nitrate réductase périplasmique de Rhodobacter sphaeroides catalyse la réduction du nitrate en nitrite. C'est une métalloenzyme qui comprend un cofacteur à molybdène, un centre fer - soufre et deux hèmes.La réactivité du cofacteur à molybdène reste mal comprise pour plusieurs raisons. Entre autres : l'hétérogénéité des signatures RPE Mo(V), état semi-réduit du site actif, et l'existence d'états inactifs de l'enzyme selon les conditions.Pour comprendre la réactivité et la pertinence catalytique des principales espèces Mo(V), nous avons entrepris une caractérisation des processus d'activation et d'inactivation par électrochimie sur film de protéines, et une étude de leur structure par spectroscopies RPE et HYSCORE.Nos observations cinétiques suggèrent que l'activation irréversible de l'enzyme implique un réarrangement d'une des ptérines du cofacteur à Mo.Ceci est mis en évidence par la modification des couplages magnétiques intercentres du fait de l'activation, et par des modifications de structure au delà de la première sphère de coordination du Mo.Enfin, l'étude de l'inactivation réversible de l'enzyme par électrochimie montre l'implication des différents états redox du site actif dans le mécanisme d'inhibition, et donne les conditions nécessaires au piégeage de formes Mo(V) activesRhodobacter sphaeroides periplasmic nitrate reductase catalyses the reduction of nitrate into nitrite. It is a metalloenzyme containing a molybdenum cofactor, an iron - sulfur cluster, and two haems.The reactivity of the molybdenum cofactor remains elusive for many reasons. Among others : the heterogeneity of the EPR signatures of Mo(V), the semi-reduced state of the active site, and the existence of inactive states of the enzyme, depending on conditions.In order to understand the reactivity and the catalytic relevance of the major Mo(V) species, we have undertaken a characterisation of the activation and inactivation processes by protein-film-electrochemistry, and a study of their structure by EPR and HYSCORE spectroscopies.Our kinetic observations suggest that the irreversible activation of the enzyme involves a rearrangement of one of the pterins of the Mo cofactor.This is evidenced by the modification of intercentre magnetic couplings due to the activation, and by structural modifications beyond the first coordination sphere of Mo.Finally, the study of enzyme reversible inactivation by electrochemistry shows the involvement of the different redox states of the active site in the inhibition mechanism, and yields the necessary conditions to trapping active Mo(V) forms
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Jacques, Julien. "Réactivité de la nitrate réductase périplasmique étudiée par spectroscopie RPE et électrochimie directe." Electronic Thesis or Diss., Aix-Marseille, 2014. http://www.theses.fr/2014AIXM4710.
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La nitrate réductase périplasmique de Rhodobacter sphaeroides catalyse la réduction du nitrate en nitrite. C'est une métalloenzyme qui comprend un cofacteur à molybdène, un centre fer - soufre et deux hèmes.La réactivité du cofacteur à molybdène reste mal comprise pour plusieurs raisons. Entre autres : l'hétérogénéité des signatures RPE Mo(V), état semi-réduit du site actif, et l'existence d'états inactifs de l'enzyme selon les conditions.Pour comprendre la réactivité et la pertinence catalytique des principales espèces Mo(V), nous avons entrepris une caractérisation des processus d'activation et d'inactivation par électrochimie sur film de protéines, et une étude de leur structure par spectroscopies RPE et HYSCORE.Nos observations cinétiques suggèrent que l'activation irréversible de l'enzyme implique un réarrangement d'une des ptérines du cofacteur à Mo.Ceci est mis en évidence par la modification des couplages magnétiques intercentres du fait de l'activation, et par des modifications de structure au delà de la première sphère de coordination du Mo.Enfin, l'étude de l'inactivation réversible de l'enzyme par électrochimie montre l'implication des différents états redox du site actif dans le mécanisme d'inhibition, et donne les conditions nécessaires au piégeage de formes Mo(V) activesRhodobacter sphaeroides periplasmic nitrate reductase catalyses the reduction of nitrate into nitrite. It is a metalloenzyme containing a molybdenum cofactor, an iron - sulfur cluster, and two haems.The reactivity of the molybdenum cofactor remains elusive for many reasons. Among others : the heterogeneity of the EPR signatures of Mo(V), the semi-reduced state of the active site, and the existence of inactive states of the enzyme, depending on conditions.In order to understand the reactivity and the catalytic relevance of the major Mo(V) species, we have undertaken a characterisation of the activation and inactivation processes by protein-film-electrochemistry, and a study of their structure by EPR and HYSCORE spectroscopies.Our kinetic observations suggest that the irreversible activation of the enzyme involves a rearrangement of one of the pterins of the Mo cofactor.This is evidenced by the modification of intercentre magnetic couplings due to the activation, and by structural modifications beyond the first coordination sphere of Mo.Finally, the study of enzyme reversible inactivation by electrochemistry shows the involvement of the different redox states of the active site in the inhibition mechanism, and yields the necessary conditions to trapping active Mo(V) forms
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Melin, Sofie, and Isabelle Samnell. "Musikens påverkan på fysisk prestation, subjektivt skattad ansträngning och upplevd koncentration : - en studie beträffande musik kontra tystnad vid Coopertest gjord på 32 ungdomar och unga vuxna mellan 15-30 år." Thesis, Uppsala universitet, Fysioterapi, 2016. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-311575.
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Bakgrund: Musik påverkar muskelspänning, hjärtfrekvens, blodtryck och känslor. En ökning av positiva känslor kan ge en bättre prestation. Syfte: Att undersöka musikens påverkan på fysisk prestation mätt i tid, subjektivt skattad ansträngningsgrad och upplevd koncentration. Samt om musikens påverkan på prestation skiljer sig mellan kön och hur fysisk prestation samverkar med subjektivt skattad ansträngningsgrad. Metod: Studien var en kvasiexperimentell engruppsstudie med komparativ och korrelerande design. Urvalet bestod av 32 individer med varierande löpvana. Könsfördelningen var 17 kvinnor och 15 män och åldersspannet var 15-30 år. Resultat: En prestation mätt i tid vid ett Coopertest var signifikant bättre med musik än utan (p=0,002). Det gällde hos både kvinnor (p=0,017) och män (p=0,032). Det visades däremot ingen signifikant skillnad inom subjektivt skattad ansträngningsgrad eller upplevd koncentration vid löpning med och utan musik. Ett lågt till måttligt negativt samband fanns mellan subjektivt skattad ansträngningsgrad och uppmätt tidsresultat vid Coopertest med (Spearmans rho = -0,37) och utan musik (Spearmans rho= -0,43). Konklusion: Musik tenderar att prestationshöja individers fysik. Detta gäller individerna i denna studie och är inte direkt överförbart till andra grupper. Inom fysioterapi kan musik vara ett alternativ för patienter som har svårt att motiveras till att träna med önskad intensitet.Background: Music affect the muscle tension, heart rate, blood pressure and emotions. An increase of positive emotions may result in a better performance. Aim: To explore the impact of music on physical performance measured in time, perceived exertion and perceived concentration and also if the impact differs between the sexes and how physical performance interacts with perceived exertion level. Method: The study was a quasi-experimental single-group study with comparative and correlating design. The sample consisted of 32 individuals with varying experience of running. They were 17 women and 15 men in the age of 15-30 years old. Results: A performance measured in time at the Cooper Test was significantly better with music than without (p = 0.002). It was shown in both women (p = 0.017) and men (p=0.032). There was no significant difference in perceived exertion or perceived concentration in running with and without music. A low to moderate negative correlation was found between perceived exertion and the measured time results at the Cooper Test with (Spearman's rho = -0.37) and without music (Spearman's rho = -0.43). Conclusion: Music tends to increase a performance based on individual physics. This is related to the individuals in this study and can not be directly transferable to other groups. In physiotherapy, music can be an option for patients who find it difficult to train with the desired intensity
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SILVA, NETO Leoncio de Barros e. "Caracterização de dosímetros de alanina/RPE para irradiadores de raios-X de baixa energia." Universidade Federal de Pernambuco, 2016. https://repositorio.ufpe.br/handle/123456789/19638.
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FACEPE
Nos últimos anos, a crescente dificuldade para aquisição e transporte internacional de irradiadores de raios gama, como o irradiador de Co-60 GammaCell 220 da Nordion, levou ao desenvolvimento de irradiadores de altas taxas de dose com base em feixes de raios-X, que operam na faixa de 150kV. Uma das aplicações deste tipo de irradiador é a irradiação de insetos, de amostras de sangue, etc. Para estes procedimentos, é importante que se tenha dosímetros que possam monitorar os processos de irradiação. O objetivo deste trabalho é o estudo e caracterização da alanina para que possa ser aplicada em dosimetria de irradiadores de raios-X de altas taxas de dose. A alanina é um aminoácido com número atômico efetivo próximo ao do tecido humano e é utilizada para dosimetria por ressonância paramagnética eletrônica (RPE) para aplicações em radioterapia. Neste trabalho, foram produzidas pastilhas de alanina com diferentes aglutinantes, bem como pastilhas puras revestidas com duas camadas de verniz, para serem utilizadas como dosímetros. Foram utilizados como aglutinantes parafina, teflon e estearina em concentrações de 1 %, 2 % e 5 % da massa total das pastilhas. Testes mecânicos, como ultrassom e rot-up, foram realizados para avaliar a resistência mecânica das pastilhas produzidas. Após os testes mecânicos, verificou-se que as pastilhas preparadas com alanina pura apresentavam resistência mecânica suficiente para serem utilizadas como dosímetros. A reprodutibilidade de sua resposta RPE foi avaliada a partir da irradiação de dez dosímetros com dose de 100 Gy com uma fonte de Co-60. Para investigar a estabilidade da resposta da alanina-RPE com o tempo, três dosímetros foram irradiados com uma dose de 200 Gy com uma fonte de Co-60, sendo a leitura realizada após cinco horas da irradiação e releituras após 15, 40, 87, 110 e 137 dias da irradiação. Para obter as curvas de calibração para raios gama e raios – X, amostras foram irradiadas, respectivamente, com doses de 0 a 1 kGy e de 18,7 Gy a 206 Gy. Os resultados mostram que a resposta dos dosímetros de alanina-RPE apresentou reprodutibilidade com um coeficiente de variação de 1,2%. O estudo do desvanecimento da resposta dos dosímetros mostrou uma variação de 0,8% em 137 dias. De acordo com os resultados obtidos, o sistema de dosimetria alanina-RPE pode ser utilizado, de forma confiável, como um sistema padrão de transferência para as aplicações do irradiador de raios-X de baixa energia, o RS 2400.
In recent years, the increasing difficulty in acquisition and international transport of gamma ray radiators, as irradiator Co-60 Gammacell 220 of Nordion led to the development of high dose rate irradiators based on X-ray beams that they are operating in the 150kV range. One application of this type of irradiator and irradiation of insects, blood samples, etc. For these procedures, it is important to have dosimeters that can monitor the irradiation processes. The objective of this work is the study and characterization of alanine that can be applied in dosimetry irradiating X-ray of high dose rates. Alanine is an amino acid in effective atomic number close to that of human tissue and is used for dosimetry for electron paramagnetic resonance (EPR) for applications in radiotherapy. In this work, alanine pellets were produced with different binders as well as pure tablets coated with two coats of varnish to be used as dosimeters. They were used as binders paraffin, teflon and stearin in concentrations of 1%, 2% and 5% of the total mass of the pastilles. Mechanical tests, such as ultrasound and rot-up were conducted to evaluate the mechanical strength of the tablets produced. After mechanical testing, it was found that the tablets prepared with pure alanine had sufficient mechanical strength to be used as dosimeters. The reproducibility of EPR response was evaluated from the irradiation ten dosimeters with dose 100 Gy with a source of Co-60. To investigate the stability of alanine EPR response over time of three dosimeters were irradiated with a dose of 200 Gy with a source of Co-60, the reading being performed after five hours of irradiation and readings after 15, 40, 87, 110 and 137 days of irradiation. To obtain the calibration curves for gamma rays and X - ray irradiated samples were, respectively, at doses from 0 to 1 kGy and 18.7 Gy to 206 Gy. The results show that the response of EPR-alanine dosimeters showed reproducibility with a coefficient of variation 1.2%. The study fading dosimeters response showed a variation of 0.8% in 137 days. According to the results, the system alanine EPR dosimetry can be used reliably as a pattern transferring system for irradiating the applications of low-energy X-rays, the RS 2400.
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Pritchett, Robert. "RPE "Drift" in Fit and Unfit Males Cycling in a Hot and Cool Environment." TopSCHOLAR®, 2003. http://digitalcommons.wku.edu/theses/562.
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The potential influence of aerobic fitness on RPE estimations during extended exercise bouts is not well understood. The current study compared RPE-Overall, RPE-Legs and RPE-Chest between fit (n=7) and unfit (n=6) males. Subjects completed a graded cycling test and then, in a counterbalanced order, on two separate days cycled for 60min (intensity~90% of the Onset of Blood Lactate Accumulation (OBLA) - determined via gas exchange indices) at 30}1 degrees Wet Bulb Globe Temperature (WBGT) and 18}1 degrees WBGT. Heart rate (HR), rectal temperature (Tree) and overall and differentiated RPE estimations were collected every 5 minutes. Repeated measures analyses of variance showed no significant differences (p>0.05) between groups for RPE-O, RPE-L, RPE-C. There were no significant differences between groups across time for HR or Tree. Similarly, there was no significance between - group differences for core temperature increase (Tree at 60min – Tree at 0 min) or absolute HR drift (HR at 60min- HR at 5min) within cool or hot cycling trials. This suggests fit and unfit males experienced similar relative cardiovascular and thermal strain. Results indicate that, between fit and unfit males cycling at similar individualized relative intensities, overall and differentiated RPE estimations are not influenced by aerobic fitness level during 60 minutes of exercise in 18 or 30 degrees WBGT.
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Tao, Qianping. "Characterization and modulation of ionic conductances in cultured rabbit retinal pigment epithelial (RPE) cells." Thesis, National Library of Canada = Bibliothèque nationale du Canada, 1997. http://www.collectionscanada.ca/obj/s4/f2/dsk3/ftp04/nq24762.pdf.
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Ratnayaka, Janaka Arjuna. "Trafficking and processing of variant B cystatin C and endogenous SPARC in RPE cells." Thesis, University of Liverpool, 2006. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.440770.
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Faby, Hendrik [Verfasser]. "Temperaturabhängige VEGF Induktion im humanen RPE - Mögliche Bedeutung für die Transpupilläre Thermotherapie / Hendrik Faby." Kiel : Universitätsbibliothek Kiel, 2016. http://d-nb.info/111473506X/34.
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Ceotto, Filho Gino. "RPE dos portadores de carga E Mn2+ em compostos de grafite intercalado com ALCL3." [s.n.], 1987. http://repositorio.unicamp.br/jspui/handle/REPOSIP/277564.
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Orientador: Carlos RettoriDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Fisica Gleb Wataghin
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Resumo: O objetivo deste trabalho constituiu em preparar compostos de grafite intercalados com AlCl3, com o intuito inicial de, através de experimentos de Ressonância Paramagnética Eletrônica (RPE) em função da temperatura, tentar, pelo acompanhamento dos espectros de ressonância dos portadores de carga e da impureza magnética, caracterizar melhor o tipo de transição de fase observadas nestes sistemas. Experimentos de RPE em função da temperatura (T = 4,2K e 90 £ T £ 375K) realizados no composto intercalado de estágio 2, tivemos oportunidade de observar pela primeira vez, paralelamente com Ressonância de Spin dos Portadores de Carga (RSPC), o espectro de estrutura fina e hiperfina, completamente resolvido, do íon Mn2+ numa matriz metálica. Os resultados mostraram que os íons Mn2+ estão localizados num campo cristalino de simetria axial, com o eixo de simetria perpendicular às camadas de carbono. O parâmetro de segunda ordem de campo cristalino (D) aumentou com a temperatura, comportamento este contrário ao usualmente observado em isolantes. Já o "splitting" hiperfino mostrou ser independente da temperatura. O alargamento da ressonância do Mn2+ observada para T > 200K permitiu-nos extrair a dependência para altas temperaturas (200K < T < 375K) do tempo de relaxação spin-rede (T1). Através do método do fator de saturação da ressonância medimos T1 a 4,2K. Uma mudança brusca no valor de g e na largura da linha da ressonância dos portadores de carga, como também na intensidade e parâmetro D do íon Mn2+ , para T @ 200K, sugere a existência de uma transição de fase a esta temperatura
Abstract: Not informed.
Mestrado
Física
Mestre em Física
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Santos, Adevailton Bernardo dos. "Estudo preliminar de RPE em banda K de esmalte dental e hidroxiapatita sintética irradiados." Universidade de São Paulo, 2002. http://www.teses.usp.br/teses/disponiveis/59/59135/tde-26012007-213607/.
Full textAbstract:
A hidroxiapatita e o esmalte dental são, na atualidade, alguns dos materiais mais pesquisados pela técnica de espectroscopia por Ressonância Paramagnética Eletrônica ? RPE. O esmalte dental, que possui cerca de 97% de sua massa constituída por cristais de hidroxiapatita, se apresenta como o tecido humano preferencial para dosimetria de radiação com o uso desta técnica, principalmente no caso de exposições acidentais da população em geral. A análise de hidroxiapatitas sintéticas tem por finalidade auxiliar o entendimento do espectro do esmalte dental bem como desenvolver um dosímetro de radiação com boa eficiência e eficácia. O espectrômetro em banda-K utiliza uma freqüência intermediária aos espectrômetros em banda-X e em banda-Q, possuindo uma melhor resolução que banda-X sem as dificuldades, devido à alta sensibilidade, do banda-Q. O presente trabalho tem como objetivo analisar espectros em banda-K de um bloco de esmalte irradiado e de hidroxiapatitas sintéticas, comparando com espectros de banda-Q e banda-X presentes na literatura, e ainda verificar a possibilidade de se fazer dosimetria de radiação com o uso deste aparelho.Hydroxyapatite and tooth enamel are, nowadays, some of materials mostly investigated by the spectroscopic technique of Electron Paramagnetic Resonance ? EPR. Tooth enamel, that have about of 97% of its mass constituted by hydroxyapatite crystals, appears itself as the preferential human tissue for radiation dosimetry using EPR, mainly in case of accidental expositions by ordinary personnel. The analyses of synthetic hydroxyapatites have as the main goal to help the understanding of tooth enamel?s spectrum seeking the developing of a radiation dosimeter with good efficiency and accuracy. The K-band EPR spectrometer uses an intermediate frequency between the spectrometers in X-band and Q-band, possessing a better resolution than the X-band without presenting the Q-band?s difficulties. In this preliminary work the EPR spectra of a small block tooth enamel and synthetic hydroxyapatites irradiated were analyzed in K-band, comparing the results with X- and Q-band with published results, the possibility of performing radiation dosimetry at K-band was verified.
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Marque, Sylvain. "Production et études par RPE de radicaux phosphoranyle persilyles : applications en polarisation dynamique nucléaire." Aix-Marseille 3, 1996. http://www.theses.fr/1996AIX30103.
Full textAbstract:
Notre etude a concerne l'examen des perspectives qu'offrent les radicaux phosphoranyle persilyles, (r#3sio)#4p#?, dans les applications de la polarisation dynamique nucleaire a la magnetometrie des champs faibles. Nous avons prepare deux phosphite de tris(trialkylsilyle), deux peroxydes de bis(trialkylsilyloxy)phosphoranyle. La structure bpt de ces radicaux a ete determinee par des etudes de rpe en phase isotrope et anisotrope. Les etudes de cinetique ont permis de mettre en evidence un processus d'alpha scission tres lent et un processus de disparition par reaction entre le peroxyde et le radical phosphoranyle persilyle. Nos travaux nous ont permis de decouvrir les premiers radicaux phosphoranyle acycliques, persistants a temperature ambiante. Nous avons determine les differents processus de relaxation intervenant dans l'elargissement de la raie de rpe de ces radicaux. Nous avons mesure le facteur d'efficacite pour un radical phosphoranyle et calcule le facteur de polarisation dynamique. Nous avons montre que la famille des radicaux phosphoranyle persilyles possede un fort potentiel pour une application en polarisation dynamique nucleaire. L'obtention de radicaux phosphoranyle persilyles stables en solution demeure un defi pour le chimiste