Le retraitement du combustible nucléaire irradié passe par une étape de séparation de l’uranium, du plutonium et des produits de fission qui le constituent, notamment par une étape de dissolution en milieu nitrique. Dans une démarche d’amélioration continue et pour optimiser le procédé quel que soit le combustible, il est nécessaire de comprendre les phénomènes physico-chimiques, cinétique et hydrodynamiques mis en jeu lors de la dissolution, pour permettre une modélisation de ce procédé à des fins de prévision. L’état de l’art ne permet de donner que des indications limitées car il repose sur des études macroscopiques dans des réacteurs de plusieurs centaines de millilitres. Les conclusions qui peuvent en être tirées sont donc soumises à la superposition de phénomènes microscopiques liés à la complexité du milieu nitrique, à des solides à dissoudre dont la composition et plus généralement la nature sont mal définies. Il est donc nécessaire de passer par une autre démarche qui consiste à décomposer et analyser les différents processus mis en jeu. Un modèle mettant en œuvre un couplage entre hydrodynamique et cinétique de dissolution d’un solide en présence d’espèces autocatalytiques est alors proposé. Ce modèle a permis de mettre en évidence la nécessité de réaliser des observations des concentrations des espèces au niveau de l’interface réactionnelle. Un réacteur miniaturisé a alors été conçu, et des expériences ont été menées sur des billes de cuivre, simulant le combustible, et ont permis d’obtenir de premières observations de bulles de gaz formées en cours de dissolution. Une méthode originale de suivi du pH in-situ au niveau de l’interface a été mise au point : un marqueur fluorescent a permis de visualiser les acidités in-situ et une cartographie du pH a pu être dressée en cours de dissolution, de même qu’une visualisation directe des processus de transfert avec mesure des couches-limites de diffusion. Cette méthode a enfin pu être transposée en zone nucléarisée sur du dioxyde d’uranium et a conduit à la compréhension et la modélisation du procédé de dissolution en milieu nitrique. / The reprocessing of irradiated nuclear fuel passes through a stage of separation of uranium, plutonium and fission products by dissolution in nitric acid. To be able to optimize the process regardless of the fuel used, it is necessary to understand physical and chemical phenomena, kinetics and hydrodynamic parameters involved in the process, to allow its modelling and to be able to forecast behaviours during the operation. The state of the art can only provide limited guidance because it is based on macroscopic studies in reactors of hundreds of millilitres. The conclusions that can be drawn are therefore subject to the overlay of microscopic phenomena related to the complexity of the nitric mid, and to the composition and nature of the solid to dissolve that are generally poorly defined. It is therefore necessary to use another approach which is to separate and analyze the various processes involved. A model implementing a coupling between hydrodynamics and kinetics involved in the dissolution of a solid in the presence of autocatalytic species is then proposed. This model was used to highlight the need for observations of the concentrations of the species at the level of the reactive interface. A miniaturized reactor was designed, and experiments were conducted on copper beads, simulating the fuel, and provided initial observations of gas bubbles formed during dissolution. A novel method for monitoring pH in-situ at the level of the interface has been developed: a fluorescent marker enabled to visualize in-situ acidity and pH mapping during dissolution, and a direct visualization of the transfer process with diffusion layers. This method could be transposed in the nuclear area on uranium dioxide and has led to the understanding and modelling of the process of dissolution in nitric environment.

La mise au jour du mobilier archéologique ferreux s'accompagne de dégradations si ce dernier n'est pas rapidement stocké en atmosphère inerte ou traité. Dans le cas des objets provenant de fouilles sous-marines, la présence de produits de corrosion chlorurés instables au contact de l'air accélère les phénomènes de reprise de corrosion. Afin de limiter ces dégradations et de stabiliser l'objet, il est nécessaire d'extraire les ions chlorure piégés au sein du système de corrosion. Divers traitements de déchloruration ont été développés par les ateliers de conservation (immersion dans des solutions alcalines, polarisation cathodique, plasma d'hydrogène, fluide subcritique…). Ces traitements ont une efficacité certaine mais une meilleure compréhension des mécanismes de déchloruration (évolution des phases chlorurées durant le traitement, phénomènes de transport dans la couche, cinétiques d'extractions des chlorures…) permettrait de les optimiser (temps de traitement, fiabilité, reproductibilité…). Les objectifs de cette thèse sont multiples. En un premier temps la caractérisation fine du système de corrosion développé en milieu marin puis lors de son abandon à l'air a été réalisée à l'aide de techniques multi-échelles sur un corpus expérimental composé de lingots en fer forgé provenant de frégates gallo-romaines découvertes au large des Saintes-Maries-de-la-Mer (Bouches-du-Rhône, France) immergées durant 2000 ans. Il a notamment été mis en évidence que ce faciès de corrosion est principalement composé d'hydroxychlorure de fer (β-Fe2(OH)3Cl), phase chlorurée contenant près de 20% en masse de chlore. En un second temps l'évolution du système de corrosion développé en milieu marin a été suivi lors des étapes constituant un traitement de déchloruration : l'étape de traitement à proprement parlé qui consiste en la circulation d'une solution de NaOH aérée ou désaérée, l'étape de lavage puis l'étape de séchage. Ce second axe s'est déroulé en deux temps. Tout d'abord le suivi in situ de l'évolution de la couche de corrosion lors de l'étape de traitement a été réalisé sous rayonnement synchrotron par diffraction des rayons X. Puis le système de corrosion a été caractérisé à l'ssu des étapes de lavage et de séchage. Ainsi le comportement de la couche de corrosion a pu être appréhendée et une meilleure compréhension des mécanismes de déchloruration proposée. Les objectifs de cette étude sont d'une part de suivre in situ l'évolution du faciès de corrosion d'objets archéologiques lors d'un traitement en solution aérée d'hydroxyde de sodium (NaOH) et d'autre part de caractériser le faciès de corrosion après lavage et séchage de l'objet (…) / The excavation of archaeological iron artefacts are accompanied by degradation if they are not readily stored in an inert atmosphere or treated. In the case of artifacts from underwater excavations, the presence of chlorinated volatile corrosion products on contact with air accelerates the recovery of corrosion phenomena. To limit this degradation and stabilize the object, it is necessary to remove chloride ions trapped in the corrosion pattern. Various dechlorination treatments have been developed by conservation workshops (immersion in alkaline solutions, cathodic polarization, hydrogen plasma, subcritical fluid ...). Despite a genuine efficiency, these treatments need to be optimized (processing time, reliability, reproducibility ...) by a better understanding of dechlorination mechanisms (structural evolution of corrosion pattern during treatment, transport phenomena in the layer, kinetics of extraction of chlorides ...). The objectives of this study are multiple. At first the detailed characterization of the corrosion pattern developed in the marine environment and then when it was abandoned in air was performed using multiscale techniques on an experimental corpus consists of wrought iron ingots from Gallo-Roman ships discoveries off the Saintes-Maries-de-la-Mer (Bouches-du-Rhone, France) submerged for over 2000 years. In particular it was shown that the corrosion pattern of an freshly excavated object is mainly composed of the ferrous hydroxychloride β-Fe2(OH)3Cl, chlorinated phase containing about 20 wt% chlorine. In a second time the evolution of the corrosion pattern was followed during the treatment steps constituting dechlorination: the step of processing, strictly speaking, which consists of the circulation of a NaOH solution aerated or deaerated, step then washing the drying step. The second axis was conducted in two stages. First, the in situ monitoring of the corrosion layer's evolution in the step of processing was carried out under synchrotron radiation by X-ray diffraction coupled to the determination of chloride ions in solution extracts. Then the corrosion pattern was characterized ex situ, elementarily and structurally, from the steps of washing and drying. The whole data allowed us firstly to refine processes structural evolution of the corrosion layer at each stage and also discuss models of chloride extraction proposed in the literature

En cas de rejets de polluants ou de radionucléides dans l’atmosphère, l’estimation du lessivage des particules d’aérosol atmosphérique par les précipitations est une donnée essentielle pour évaluer la contamination de la biosphère. De nombreuses études se sont déjà intéressées à ce processus de dépôt humide, mais la plupart d’entre elles sont d’ordre théoriques ou ont été menées en laboratoire. Cette étude a donc pour objectif d’améliorer la connaissance du potentiel de lessivage des particules d’aérosol par les précipitations par une approche expérimentale en conditions in situ. Durant plusieurs mois, trois sites aux environnements distincts en termes de climatologie et d’empoussièrement ambiant ont été instrumentés pour disposer d’une palette de situations précipitations/empoussièrement la plus variée possible. Un disdromètre laser et un granulomètre (compteur électrique et/ou optique) ont mesurés respectivement les caractéristiques des précipitations et les concentrations de particules à une résolution temporelle élevée et sur une large gamme de diamètre. L’utilisation de ce couplage instrumental original a permis de déterminer les potentiels de lessivage pour des particules de la gamme nanométrique à supermicronique et pour différents types de précipitations (chutes de neige et pluies avec des hyétogrammes spécifiques). Dans un premier temps, le coefficient de lessivage ᴧ (paramètre décrivant la cinétique du processus) a été calculé en considérant l’effet global d’une précipitation. Cette approche « macroscopique » est limitée par l’influence de processus « concurrents », tels que l’advection ou les sources d’émissions de particules à proximité des sites de mesures. Pour minimiser l’impact de ces processus sur nos résultats, une seconde méthodologie basée sur la résolution temporelle élevée de l’instrumentation utilisée a été définie. Par cette approche « intra-évènementielle », les coefficients de lessivage ᴧ sont calculés sur de courtes périodes de temps, permettant ainsi d’étudier l’influence de la variabilité du diamètre des particules et des caractéristiques des précipitations sur ces coefficients. Les résultats obtenus par les deux types d’approches ont mis en évidence la nécessité de prendre en compte le diamètre des particules et les caractéristiques des précipitations pour modéliser fidèlement le lessivage des particules d’aérosol atmosphérique. En comparant les résultats des deux types de précipitations, la prédominance du lessivage par des chutes de neige par rapport au lessivage par la pluie a été illustrée. L’importance du diamètre des particules lessivées a été démontrée. Entre le mode « ultrafin » et le mode « grossiers », la variation du coefficient de lessivage est d’un ordre de grandeur (entre environ 2.10¯³et 2.10¯⁴ s¯¹). Le potentiel de lessivage minimum est obtenu pour des particules d’environ 100 nm, ce qui est cohérent avec la théorie du « Greenfield gap » (entre 0,1 et 1 µm). Pour les besoins de la modélisation, une paramétrisation robuste entre le coefficient de lessivage ᴧ et le diamètre des particules d’aérosol (de 10 nm à 10 µm) a été établie. Différentes relations entre le coefficient ᴧ et l’intensité pluviométrique sont proposées aussi pour différentes gammes de diamètre de particules et comparées notamment aux valeurs implémentées actuellement dans le modèle ldX utilisé à l’Institut de Radioprotection et de Sûreté Nucléaire. / In case of release of pollutant or radionuclides into the atmosphere, estimate of below-cloud scavenging of aerosol particles by precipitation (or washout) is an essential data to evaluate contamination of the biosphere. Many studies have already shown an interest to this wet deposition process, but most of them are theoretical or have been conducted in laboratories conditions. This study in situ conditions aims to improve knowledge of below-cloud scavenging of aerosol particles by precipitation. For several months, three sites with separate environments in terms of climate and ambient dust have been instrumented to have such a varied palette of precipitation/dust conditions as possible. A laser disdrometer and a granulomètre (electrical and/or optical counter) measure respectively precipitations characteristics and particles concentrations with a high temporal resolution (one minute). The use of this original instrumental coupling has allowed determining washout potentials for the nanometric size range of particles aerosol to the supermicronique size range and for different types of precipitation (snowfalls and rainfalls with specifics hyetograms).Initially, below-cloud scavenging coefficients ᴧ (parameter describing kinetic of this process) were calculated considering the gobal effet of a precipitation. This “macroscopic” approach is limited by the influence of “concurrent” processes, as advection or local emissions of aerosol particles close to the measurements sites. To minimise effect of these processes on our results, a second methodology based on the high temporal resolution of the instrumentation used was defined. With this “intra-event” approach, washout coefficients are calculated on short time scales, allowing study of impact of the variability of aerosol size and precipitations characteristics on these coefficients.Results obtained with the two approaches highlighted the need of considering particles diameter and characteristics of precipitation to model accurately below-cloud scavenging of aerosol particles. Comparing results for both type of precipitation, predomination of below-cloud scavenging by snowfalls compared with below-cloud scavenging by rainfalls was shown. The importance of the scavenged aerosol diameter was demonstrated. From the “ultrafine” size range to coarse mode of particles, below-cloud scavenging coefficient varies by an order of magnitude (from 2.10¯³ to 2.10¯⁴ s¯¹). Minimum potential is obtained for particles of about 100 nm, which is consistent with theory of “Greenfield gap” (from 0.1 to 1 µm). For modeling needs, a robust parametrization between washout coefficient ᴧ and aerosol particles diameter (from 10 nm to 10 µm) has been established. Also some relationships between coefficient ᴧ and rainfall intensity are proposed for different particles size range and compared in particular with values implemented in model ldX currently used at the French Institute of Radioprotection and Nuclear Safety.

Trematode peptidases are important molecules responsible for biocatalysis in many basal biological processes and are crucial in host-parasite interactions. Therefore, these enzymes are intensively studied in order to characterize their biological functions and to use them as potential diagnostic or therapeutic targets. Lately, investigation of transcriptome and secretome revealed, that adult Fascioloides magna (giant liver fluke) expresses and secretes a variety of peptidases. Thus, this thesis focuses on three newly identified enzymes: cathepsin L (FmCL), cathepsin B (FmCB) and cathepsin D (FmCD). In other trematode species, these cathepsins are being linked mainly with the digestion of host blood. We applied quantitative PCR (qPCR) to investigate relative expression levels of the three enzymes among three developmental stages - egg, miracidium and adult. It was revealed that all cathepsins have the highest expression in adult flukes in comparison to eggs and miracidia. We also localized the place of transcription of FmCL, FmCB and FmCD in adult fluke using RNA in situ hybridization. All of the peptidases were detected in gastrodermis, and in addition, they were localized in the reproductive system. The latter surprising finding is suggesting that these enzymes might have multiple functions in adult F....

Foi estudado o efeito do dodecilsulfato de sódio (SDS) na ausência e presença do Benzotriazol (BTAH) sobre as interfases Cu/H2SO4 0,5 mol L-1 e Cu/HCl 1 mol L-1. Foram empregadas técnicas eletroquímicas estacionárias, impedância eletroquímica e espectroscopia Raman \"in situ\". Análise da superfície, após ensaios, foi feita por ressonância ciclotrônica de íons empregando transformada de Fourier. Nos dois meios estudados foi observado que o SDS não modifica significativamente o potencial de corrosão (Ecorr) mas favorece a dissolução do óxido de cobre formado ao ar. O SDS, o BTAH e a mistura SDS-BTAH inibem a reação W+/H2, devido à formação de um filme na superfície do cobre. Na presença de SDS, o filme obedece ao modelo de Langmuir modificado, onde cada molécula ocupa mais de um sítio ativo. Foram determinadas constantes de equilíbrio de adsorção para o SDS, iguais a 1,7x103 L mol-1 e 5,0x104 L mol-1 sobre cobre em meios de H2SO4 0,5 mol L-1 e HCl 1 mol L-1 respectivamente. O efeito sinérgico do SDS sobre a ação do BTAH foi melhor evidenciado em meio de H2SO4 0,5 mol L-1, onde se constatou a co-adsorção SDS-BTAH e a modificação dos espectros de um pela presença do outro, em toda a faixa de potenciais estudada, acima e abaixo do Ecorr. O SDS não modifica o mecanismo de dissolução do cobre em meio de H2SO4 0,5 mol L-1, no Ecorr, a baixas e altas sobretensões. Em meio de HCl 1 mol L-1, há evidências da formação do complexo Cu-OSO3-C12H25. Nos dois meios a adsorção do SDS se dá através das partes hidrofóbica e hidrofílica. / The effect of sodium dodecylsulfate (SDS) on the Cu/0.5 mol L-1 H2SO4 and Cu/1.0 mol L-1 HCl interphases in the absence and presence of benzotriazole (BTAH) has been studied. Steadystate electrochemical measurements, electrochemical impedance and \"in situ\" Raman spectroscopy were used as techniques. Surface analysis was made using Fourier transform ion cyclotron resonance (FTICR). It was observed that SDS does not change the corrosion potential value (Ecorr) but it increases the copper oxide dissolution rate in the two media studied. SDS, BTAH and the SDS-BTAH mixtures inhibit the H+/H2 reaction on the copper surface. In the presence of SDS, this film obeys a modified Langmuir model where each molecule uses more than one adsorption site. Adsorption equilibrium constants, of l.7x103 L mol-1 and 5.0x104 L mol-1, for SDS in 0.5 mol L-1 H2SO4 and 1.0 mol L-1 HCl solutions were obtained respectively. A synergetic effect of SDS on BTAH action was better observed in 0.5 mol L-1 H2SO4 medium. The SDS-BTAH co-adsorption and the change of the Raman spectra of each other has been verified on the entire range of potentials studied. SDS neighter changes the mechanism of copper dissolution in 0.5 mol L-1 H2SO4 medium at the Ecorr nor at low and high anodic overvoltages. In 1.0 mol L-1 HCl solutions there is an evidence of the Cu-OSO3C12H25 complex formation. The SDS adsorption occurs from hydrophobic and hydrophilic moieties.

La nitruration gazeuse de pièces en acier de construction est un procédé thermochimique permettant de générer un gradient de propriétés mécaniques à la surface des pièces par diffusion d’atomes d’azote. Les pièces traitées présentent un fort gradient de contraintes résiduelles et de dureté, optimales pour les applications de transmission de puissance utilisées dans les domaines de l’aéronautique ou l’automobile de compétition. L’enrichissement en azote est issu de la décomposition catalytique de l’ammoniac à la surface des pièces en acier. Cependant, le procédé reste extrêmement sensible à l’état de surface des pièces, qui inclue les caractéristiques géométriques, mécaniques mais également chimique, pouvant inhiber les propriétés de décomposition catalytique ainsi que la diffusion de l’azote. Cette désactivation peut avoir différentes origines, comme l’adsorption d’un élément poison de la réaction ou l’encrassement de la surface des pièces. Le phénomène de désactivation catalytique est étudié depuis quelques dizaines d’années. Cependant, peu de publications sont disponibles au sujet de son application dans le cas particulier de la nitruration d’aciers de construction. Comprendre l’inhibition de la nitruration permettrait d’améliorer la fiabilité industrielle de ce procédé. Afin de répondre à cette demande, une démarche expérimentale, basée sur des études de cas industriels et sur une étude bibliographique, a été mis en place. Une étude de pollution issue de résidus d’huile de coupe, de dépôt de carbone et d’empoisonnement au soufre est proposée. De plus, une démarche expérimentale visant à déterminer l’impact de pollutions mécaniques (état mécanique initial) sur le procédé de nitruration est proposée. Des analyses thermogravimétriques couplées à des observations et à la détermination des propriétés mécaniques générées par nitruration permettent d’approfondir la compréhension de ces phénomènes de désactivation des surfaces nitrurées. Suite à cette étude, la capacité d’activation de surface de trois éléments de préparation in-situ, que sont l’oxydation, l’urée et le chlorure d’ammonium, a été déterminé sur les pollutions précédemment étudiées. / The gaseous nitriding of steel parts is a thermochemical process that generates a mechanical properties gradient at the surface by nitrogen diffusion. The treated parts indicate an important residual stress and hardness gradient, optimized for power transmission applications used in aeronautics and motor sports. The increase of nitrogen concentration is due to the catalytic decomposition of ammonia at the iron-based surface of parts. However, the process is extremely sensitive to the surface state of parts that includes geometrical, mechanical but also chemical properties. This state can inhibit the catalytic decomposition properties and the nitrogen diffusion. This deactivation can have different origins, such as the adsorption of a poisoning element or the fouling of the surface of the parts. The catalytic deactivation phenomenon is studied since decades. However, few publications are available in the case of its application in the specific case of the gaseous nitriding of steel. A better understanding of the nitriding inhibition would improve the reliability of this industrial process. In order to answer this demand, an experimental approach, based on industrial case and bibliographical study, is proposed. A pollution study obtained from machining oil residues, carbon deposit, or sulfur poisoning is proposed. Moreover, an experimental approach, aiming to determine the impact of initial mechanical properties on the nitriding process is proposed. Thermogravimetric analyses coupled to observations and mechanical properties analyses enable to develop the knowledge of the nitrided surfaces deactivation processes. After this study, the surface activation capacity of three in-situ processes, namely oxidation, urea and ammonium chloride, over the previously studied contaminations is determined.

The three most common rock mass classification systems in use in the South African mining industry today are Bieniawski’s (1976) Geomechanics or RMR System, Barton et al.’s (1974) Q-System and Laubscher’s (1990) MRMR System respectively. Of these three systems, only the MRMR Classification System was developed specifically for mining applications, namely caving operations. In response to the increased use of the MRMR Classification System in the mining industry, and concerns that the MRMR System does not adequately address the role played by discontinuities, veins and cemented joints in a jointed rock mass, Laubscher and Jakubec introduced the In-Situ Rock Mass Rating System (IRMR) in the year 2000. A quantitative comparison of the MRMR and IRMR Classification Systems has been undertaken to determine a correlation between the two classification systems, the results of which indicate that there is not a major difference between the resultant rock mass rating values derived from the two Classification Systems. Therefore, although the IRMR System is more applicable to a jointed rock mass than the MRMR System, the MRMR System should not be regarded as redundant, as it still has a role to play as a mine design tool.

Apesar de vários estudos terem demonstrado resultados promissores do uso da solução de AmF/NaF/SnCl2 no controle da erosão do esmalte dental, não existem relatos da sua associação com a irradiação do substrato com o laser de CO2, de comprimento de onda de 9,6 ?m. Desta forma, o presente estudo teve como objetivo avaliar o potencial da solução de AmF/NaF/SnCl2, associada ou não ao laser de CO2 (4,5 J/cm2, 20 Hz, 20 ?s), em controlar a erosão em esmalte dental bovino. Treze voluntários participaram desse estudo in situ, de delineamento cruzado, em 02 fases (04 dias cada), onde 04 tratamentos foram testados utilizando réplicas (n = 13): GC - nenhum tratamento (controle negativo); GF - solução de AmF/NaF/SnCl2 (controle positivo); GL - irradiação com laser de CO2 (9,6 ?m); GLF - laser de CO2 associado à solução de AmF/NaF/SnCl2. Os voluntários usaram dispositivos intra-bucais removíveis contendo 08 amostras de esmalte bovino. Na primeira fase, 07 voluntários utilizaram dispositivos intra-bucais contendo amostras dos grupos GC e GL, e outros 06 voluntários utilizaram dispositivos contendo amostras dos grupos GF e GLF. Na segunda fase, os voluntários foram cruzados, permitindo que todos os grupos experimentais fossem avaliados no meio bucal dos 13 voluntários da pesquisa. Os dispositivos intra-bucais foram removidos da boca para ciclagem erosiva ex-situ em ácido cítrico 0,65%, pH 3,6, durante 4 minutos, 2x/dia, em horários pré-determinados. As amostras foram avaliadas em perfilômetro óptico de não-contato (n = 13) para análise da perda de tecido mineral após o desafio erosivo, e um ensaio de ultramicrodureza transversal (n = 13) foi realizado com o objetivo de determinar a profundidade da área de desmineralização abaixo da superfície do esmalte erodido. A análise morfológica foi realizada utilizando microscopia eletrônica de varredura (MEV) (n = 3). Os dados foram analisados estatisticamente por meio do modelo ANOVA 2 fatores para medidas repetidas, com subsequente comparação entre os diferentes tratamentos (? = 0,05). A ciclagem ácida realizada no presente estudo provocou perda de esmalte significativamente maior (p < 0,001) nos grupos GC (4,8 ± 1,4A ?m) e GL (4,4 ± 2,0A ?m). Não houve diferença estatística entre a perda de superfície nos grupos GF (1,9 ± 0,9B ?m) e GLF (1,7 ± 0,9B ?m). Os resultados de ultramicrodureza transversal mostraram que as amostras tratadas com a solução fluoretada (grupo GF) apresentaram uma zona parcialmente desmineralizada com média de dureza semelhante às amostras do grupo que não recebeu qualquer tipo de tratamento (grupo GC), com ambos os grupos apresentando média de dureza significativamente maior que os grupos que foram irradiados com o laser de CO2 (GL e GLF) (p < 0,001). As micrografias mostraram que as características morfológicas superficiais do esmalte nos grupos irradiados com laser de CO2 apresentaram-se semelhantes nos grupos GL e GLF, verificando-se a presença de áreas sugestivas de derretimento, resolidificação, microporos e microtrincas, sem evidências de precipitados fluoretados no grupo GFL. Uma camada amorfa pôde ser observada nas superfícies de esmalte tratadas apenas com a solução fluoretada contendo estanho. Pode-se concluir que o uso do enxaguatório bucal fluoretado contendo estanho (500 ppm F-, 800 ppm Sn2+, pH = 4,5) mostrou potencial de prevenção da erosão de esmalte dental. A irradiação do esmalte dental com o laser associado à solução fluoretada mostrou-se eficaz, mas seu efeito não foi sinérgico. O laser de CO2 (9,6 ?m), nos parâmetros utilizados, não foi capaz de prevenir a erosão em esmalte causada por ácido cítrico. / Although several studies have shown promising results using the AmF/NaF/SnCl2 solution in preventing the erosion of dental enamel, there are no reports of their association with the irradiation of the substrate with the CO2 laser, working at 9.6 ?m. Thus, this study aimed to evaluate the potential of AmF/NaF/SnCl2 solution, associated or not to CO2 laser irradiation (4.5 J/cm2, 20 Hz, 20 ?s), to prevent erosion on dental enamel. Thirteen volunteers participated in this 2-phase (4 days each), crossover study, where 04 treatments were tested using replicas (n = 13): GC - no treatment (negative control); GF - AmF/NaF/SnCl2 solution (positive control); GL - CO2 laser irradiation (9.6 ?m); GLF - CO2 laser irradiation associated with AmF/NaF/SnCl2 solution. The volunteers wore removable intra-buccal appliances containing eight bovine enamel samples. In the first phase, seven volunteers used intra-oral appliances containing samples of groups GC and GL and 6 volunteers, appliances containing samples of groups GF and GLF. In the second phase volunteers were crossed over, allowing all experimental groups were evaluated in the buccal environment of the 13 volunteers. Intra-buccal appliances were removed from the mouth and were exposed to a daily ex-situ erosive cycling (0.65% citric acid, pH 3.6, for 4 minutes, 2x/day) at pre-determined times. Samples were evaluated for surface loss using an optical non-contact profilometer (n = 13) for analysis of loss of mineral after the erosive challenge and a cross-sectional nanohardness test (n = 13) was carried out in order to determine the depth of demineralized area below the erosive lesion. Morphological analysis was carried out using scanning electron microscopy (SEM) (n = 3). The data were statistically analyzed by two-way ANOVA repeated measures with subsequent pairwise comparison test (? = 0.05). Erosive challenge significantly increased enamel wear (p < 0.001) in GC (4.8 ± 1.4A ?m) and GL (4.4 ± 2.0A ?m) groups. There was no significant difference between the surface loss in GF (1.9 ± 0.9B ?m) and GLF (1.7 ±0.9B ?m) groups. Data from cross-sectional nanohardness showed that samples treated with stannous fluoride solution (GF group) showed a partially demineralized zone with average hardness similar to samples in the group that did not receive any treatment (GC group), both groups had significantly higher average nanohardness than the irradiated samples (GL and GLF group) (p < 0.001). Morphologically, all CO2 laser irradiated samples resulted in similar changes, showing the presence of areas suggestive of melting, resolidification and some microcracks. No fluoride precipitates were observed in GFL groups. An amorphous layer could be observed on the surface of enamel treated with tin-containing solution alone. Within the limits of this in situ study, it can be concluded that the AmF/NaF/SnCl2 solution (500 ppm F, 800 ppm Sn2+, pH = 4.5) showed potential for prevention of dental enamel erosion. The enamel irradiation with the CO2 laser associated with the fluoride solution was effective, but its effect was not synergistic. The CO2 laser (9.6 ?m), with the parameters considered in this study, was not able to prevent the enamel erosion caused by citric acid.

INTRODUÇÃO: A leucemia promielocítica aguda (LPA) é um subtipo distinto de leucemia mielóide aguda (LMA), caracterizado pela presença de um acúmulo de promielócitos anormais na medula óssea e/ou sangue periférico, riscos de coagulopatias e por alterações cromossômicas estruturais envolvendo sempre o locus gênico para o receptor alfa do ácido retinóico (RAR). Corresponde morfologicamente aos subtipos M3 e M3variante de LMA, segundo a Classificação Franco- Américo- Britânica (FAB) e ao subtipo de LMA associada à translocação recíproca e balanceada entre os cromossomos 15 e 17[t(15;17)] e variantes, segundo a classificação da Organização Mundial de Saúde. O curso clínico da LPA tem sido modificado, nos últimos anos, de uma leucemia aguda rapidamente fatal para um dos mais curáveis subtipos de LMA. A introdução de agentes terapêuticos que atuam diretamente na lesão molecular, como o ATRA e o Trióxido de Arsênico, teve grande impacto na sobrevida da LPA. A eficácia do tratamento é dependente do rearranjo genético presente nas células leucêmicas, o diagnóstico morfológico é sugestivo da alteração genética, devendo ser rapidamente confirmado por técnicas de citogenética molecular. MÉTODOS: Utilizando a citogenética convencional e molecular (FISH) com sondas de fusão para o rearranjo PML-RAR e de ruptura para o gene RAR, analisou-se 62 pacientes portadores de LPA, diagnosticados por estudo morfológico/imunofetípico no HC-FM/USP entre os anos de 1997 a 2006. RESULTADOS: Dos 62 pacientes analisados, 37 (59,7%) apresentaram a t(15;17)(q22;q21) visível no cariótipo; destes, 26 (42,0%) apresentaram a t(15;17) como anormalidade clonal isolada, 10 (16,1%) apresentaram outras alterações cromossômicas clonais em adição a t(15;17) e um paciente (1,6%) apresentou uma variante complexa da t(15;17). Dezoito pacientes (29%) tiveram a confirmação da presença da t(15;17)-rearranjo PML-RAR através da técnica de FISH-fusão e sete (11,3%) não apresentaram ruptura no RAR. Ausência de sangramento ao diagnóstico (p<0,02) e a presença de morfologia M3v (p<0,01) se associaram à ausência ruptura no RAR. A taxa de sobrevida global (SG) em dois anos, entre os 55 pacientes que apresentaram a t(15;17)-rearranjo- PML-RAR ao diagnóstico citogenético, foi de 49,28%. Duas variáveis prognósticas mostraram estar estatisticamente relacionadas à pior taxa de SG nesse estudo: idade acima de 60 anos e presença de morfologia de M3v. A taxa de Sobrevida Livre de Doença em dois anos nesses pacientes foi de 72,10%.CONCLUSÃO: Cerca de 11% dos pacientes diagnosticados para LPA, através de estudo morfológico/imunofenotípico, não apresentaram diagnóstico citogenético compatível para esta doença. Na ausência de sangramento ao diagnóstico e na presença de morfologia M3v o teste de FISH deve ser priorizado. / INTRODUCTION: Acute promyelocytic leukemia (APL) is a distinct subtype of acute myeloid leukemia (AML), characterized by clonal expansion of myeloid precursors blocked at promyelocytic stage, risks of coagulopathy and presence of chromosomal translocations involving RAR (retinoic acid receptor ) gene. Corresponds to the M3 and M3variant subtypes of AML, according to the French-American-British (FAB) classification and the subtype of AML associated with balanced reciprocal translocation between chromosomes 15 and 17 [t (15; 17)] and variants, according to the World Health Organization classification. The clinical APL course has been changed in late years, from highly fatal to highly curable subtype of AML. The introduction of therapeutic agents that act directly on the molecular lesion, such as ATRA and arsenic trioxide, had a great impact on survival of APL. The efficacy of treatment is dependent on genetic rearrangement present in the leukemia cells, the morphologic diagnosis although predictive of the specific genetic lesion genetic, should be quickly confirmed by molecular techniques. METHODS: We analysed cytogenetics findings in 62 patients diagnosed as promyelocytic leukemia by morphological and immunophenotypic studies at the Hematology Service of Clinical Hospital of Sao Paulo Medical School from 1997 to 2006. For this, we used karyotype and FISH with PML-RARA fusion translocation and RARA break-apart probes. RESULTS: Of the 62 patients studied, 59.7% showed the t(15;17)(q22;q21) visible in the karyotype [42.0% had t(15;17) as the sole clonal abnormality, 16.1% showed other additional abnormalities and 1.6% had a complex variant of t(15;17)], 29% had the confirmation of the rearrangement PML-RAR through the FISH-fusion technique and 11.3% showed no break in RAR. No bleeding at diagnosis (p<0.02) and the presence of M3v morphology (p<0.01) were associated to no RAR rearrangement. The 24months overall survival of 55 patients with t(15;17) confirmed by cytogenetics was 49.28%. Two parameters were associated to worse rate of overall survival in this study: age > 60 years and M3v morphology . The 24 months disease-free survival was 72.10%. CONCLUSION: 11,3% of patients diagnosed as promyelocytic leukemia by morphological and immunophenotypic studies, showed no consistent cytogenetic diagnosis for this disease. In the absence of bleeding at diagnosis and in the presence of the M3v morphology, FISH test should be prioritized.

A flor se caracteriza como um ramo altamente modificado, especializado na reprodução das angiospermas. Por ser responsável por um processo tão crucial no ciclo de vida das plantas, o desenvolvimento das flores é estritamente regulado por vias genéticas e sinais ambientais que controlam a transição da fase vegetativa para fase reprodutiva. Esse controle culmina na determinação no meristema floral, o qual se diferenciará nos quatro verticilos florais: sépalas, pétalas, estames e pistilo. Dentre os quatro verticilos, os estames e o pistilo são os órgãos responsáveis pela reprodução, logo é de suma importância compreender mecanismos moleculares responsáveis pelo correto desenvolvimento desses órgãos. Com o intuito de melhor compreender o desenvolvimento do pistilo, nosso grupo de pesquisa fez a caracterização inicial de um gene preferencialmente expresso no pistilo de Nicotiana tabacum, que controla a proliferação celular nesse órgão e foi denominado SCI1 (Stigma/style Cell-cycle Inhibitor 1). No entanto, seu mecanismo de ação ainda não foi elucidado. Avanços nas investigações tem revelado uma extensa rede de proteínas com as quais SCI1 interage, o que permitiu assumir que SCI1 está envolvido em vias de processamento de RNA e no ciclo celular. Seu envolvimento em processos celulares básicos, levantou a hipótese de uma possível expressão no início do desenvolvimento floral. Portanto, este trabalho teve por objetivos determinar onde e quando o gene SCI1 inicia sua expressão em flores de Nicotiana tabacum; relacionar a expressão de SCI1 com o desenvolvimento do pistilo; e analisar a regulação transcricional de SCI1. Através da hibridização in situ foi possível determinar que SCI1 inicia sua expressão no meristema floral e segue se expressando intensamente nos primórdios iniciais dos verticilos florais. A expressão de SCI1 no meristema floral e primórdios dos verticilos indica que este gene pode estar envolvido no desenvolvimento de todos os verticilos florais. A medida que os verticilos se especificam, a expressão de SCI1 é reduzida, exceto no pistilo, órgão em que se localizam as últimas células meristemáticas a se diferenciarem. O mRNA de SCI1 foi detectado tanto nos carpelos não fusionados, quanto já fusionados. A hibridização in situ também revelou a coexpressão de SCI1 com o gene NAG1 no meristema floral, nos verticilos dos estames e carpelos. NAG1 codifica um fator de transcrição responsável pela especificação do terceiro e quarto verticilos florais e SCI1 foi descrito como um gene que controla o desenvolvimento de estigmaxv e estilete, estruturas que fazem parte do quarto verticilo, logo essa co-expressão revela uma possível interação desse fator de transcrição com o promotor de SCI1. Essa interação foi predita in silico e confirmada em ensaio de mono híbrido (Yeast One Hybrid) com uma porção do promotor de SCI1, denominada frag1, que compreende 443pb acima do códon de iniciação (ATG). Análises in silico também encontraram um putativo sítio para a interação do fator de transcrição WUSCHEL nesse mesmo fragmento, no entanto os resultados obtidos nos ensaios de mono híbrido para esta interação foram inconclusivos. Plantas transgênicas expressando a proteína SCI1 em fusão traducional a GFP, sob controle do promotor endógeno de SCI1, foram capazes de reproduzir a expressão endógena desse gene e possibilitaram determinar a localização da proteína. Como o mRNA, a proteína SCI1 é encontrada a partir do meristema floral e em todos os verticilos florais. A medida que a flor se desenvolvia, a proteína foi reduzindo sua quantidade de maneira centrípeta nos verticilos, no entanto essa redução não foi observada no pistilo até o estádio 2, estádio em que foi possível a observação (devido ao tamanho da flor). Nessas plantas também foi possível detectar a proteína SCI1 nos tecidos especializados do estilete e estigma, tecido transmissor do estilete e zona secretória do estigma, respectivamente, assim como nas células do parênquima. Essas plantas também possibilitaram observar a proteína nos óvulos e confirmar sua localização em núcleo e nucléolo. Esse conjunto de dados confirmam a hipótese da expressão de SCI1 no meristema floral. Além disso, os resultados demonstram que a expressão de SCI1 é regulada diretamente pelo fator de transcrição NAG1 / The flower is characterized as a highly modified branch, specialized in the reproduction of angiosperms. Since it is responsible for such a crucial process in the life cycle of plants, flower development is strictly regulated by genetic pathways and environmental signals that control the transition from the vegetative phase to the reproductive phase. This control culminates in the floral meristem determination, which will differentiate in the four flower whorls: sepals, petals, stamens and pistil. Among the four whorls, stamens and pistil are the organs responsible for reproduction, so it is extremely important to understand the molecular mechanisms responsible for the correct development of these organs. In order to better understand the development of pistil, our research group made the initial characterization of a gene preferentially expressed in the pistil of Nicotiana tabacum, which controls cell proliferation in this organ and was denominated SCI1 (Stigma/style Cell-cycle Inhibitor 1). However, its mechanism of action has not yet been elucidated. Advances in the investigations have revealed an extensive network of proteins with which SCI1 interacts, which has allowed to assume that SCI1 is involved in RNA processing pathways and in the cell cycle. Its involvement in basic cellular processes, raised the hypothesis of a possible expression at the beginning of floral development. Therefore, this work had as objectives to determine where and when the SCI1 gene starts its expression in flowers of Nicotiana tabacum; to correlate SCI1 expression to pistil development; and to analyze the transcriptional regulation of SCI1. Through in situ hybridization, it was possible to determine that SCI1 starts its expression in the floral meristem and continues to express intensely in the early primordia of floral whorls. The expression of SCI1 in floral meristem and whorl primordia indicates that this gene may be involved in the development of all floral whorls. As the whorls are specified, the expression of SCI1 is reduced, except in the pistil, organ in which the last meristematic cells are located. SCI1 mRNA was detected in both unfused and fused carpels. In situ hybridization also revealed the co-expression of SCI1 with the NAG1 gene in the floral meristem, in the whorls of stamens and carpels. NAG1 encodes a transcription factor responsible for the specification of the third and fourth floral whorls and SCI1 was described as a gene that controls the development of stigma and style, structures that are part of the fourth whorl, so this co-expression reveals a possible interaction of this transcription factor with the SCI1 promoter. This interaction was predicted in silico and confirmed in a Yeast One Hybrid assay with a portion of the SCI1 promoter, called frag1, comprising 443bp upstream the initiation codon (ATG). In silico analyzes also found a putative site for the interaction of the WUSCHEL transcription factor in this same fragment, however the results obtained in Yeast One Hybrid assays for this interaction were inconclusive. Transgenic plants expressing the SCI1 protein in translational fusion to GFP, under the control of the endogenous SCI1 promoter, were able to reproduce the endogenous expression of this gene and enabled to determine the location of the protein. Like the mRNA, the SCI1 protein is found since the floral meristem and on all floral whorls. As the flower developed, the protein was reducing its amount in a centripetal way in the whorls, however this reduction was not observed in the pistil until the stage 2, the last stage in which the observation was possible (due to the size of the flower). In these plants it was also possible to detect the SCI1 protein in the specialized tissues of style and stigma, stylar transmitting tissue and stigmatic secretory zone, respectively, as well as in the parenchyma cells. These plants also allowed the observation of the protein in ovules and to confirm its localization in nucleus and nucleolus. This data set confirms the hypothesis of SCI1 expression in floral meristem. In addition, the results demonstrate that SCI1 expression is directly regulated by the transcription factor NAG1