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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
491

Influence de la couche limite convective sur la réactivité chimique en Afrique de l'Ouest / Impact of convective boundary layer on the chemical reactivity in West Africa

Brosse, Fabien 04 December 2017 (has links)
Cette thèse porte sur l'influence de la couche limite convective et nuageuse sur la réactivité chimique en Afrique de l'Ouest. Pour répondre à cette question, des simulations à haute résolution (50m) sont réalisées sur le modèle atmosphérique Méso-NH couplé à un mécanisme chimique détaillé représentant la chimie gazeuse et aqueuse. Cette échelle spatiale permet de représenter explicitement les caractéristiques spatiales et temporelles des structures turbulentes. Les thermiques en couche limite sont identifiés à l'aide d'un échantillonnage conditionnel basé sur l'utilisation d'un traceur passif à décroissance radioactive. L'impact du transport turbulent sur la redistribution d'espèces chimiques dépend du temps de vie chimique de ces espèces. La ségrégation spatiale créée au sein de la couche limite augmente ou réduit les taux de réaction moyens entre composés. La campagne de terrain AMMA, et plus récemment DACCIWA, sont utilisées pour définir des forçages dynamiques et chimiques pour des environnements simulés. Le premier est représentatif d'un environnement biogénique dominé par des émissions naturelles de COV. Le second reproduit un environnement urbain modérément pollué typique du Golfe de Guinée (Cotonou au Bénin). Pour simplifier, l'analyse des simulations est limitée aux réactions chimiques entre OH et l'isoprène dans le cas biogénique, entre les aldéhydes C>2 et OH dans le cas urbain. L'influence de la couche limite convective est étudiée à l'échelle du thermique et du domaine. Cela permet une connexion avec les modèles à résolution plus lâche qui adoptent une hypothèse de mélange parfait et immédiat, négligeant de fait les variabilités spatiales de composés chimiques au sein d'une maille. Les premiers résultats, basés sur la phase gazeuse uniquement, montrent que les nuages en couche limite convective affectent le transport vertical d'espèces chimiques. Les thermiques sont des zones de réactions privilégiées où la réactivité chimique est maximale. La plus grande intensité de ségrégation est calculée au sommet de la couche limite, toutefois de signes opposés entre les deux environnements. En environnement biogénique, le mélange non-homogène de l'isoprène et de OH dans cette zone induit une diminution maximale de 30% du taux de réaction moyen. Dans le cas urbain, la constante de réaction effective entre OH et les aldéhydes est supérieure de 16% à la constante moyenne. La réactivité de OH est supérieure de 15 à 40% dans les thermiques comparé au reste du domaine, dépendant de l'environnement chimique et de l'heure. Comme les thermiques occupent une faible portion du domaine, l'impact des structures turbulentes sur la réactivité totale de OH est une diminution de 9% pour le cas biogénique et une augmentation maximale de 5% dans le cas anthropique. Des simulations LES incluant la réactivité aqueuse révèlent une baisse importante des rapports de mélange de OH associée à la présence de nuages. / This thesis focuses on the influence of the convective and cloudy boundary layer on the chemical reactivity in West Africa. To answer this question, high resolution simulations (50m) are performed on the atmospheric model Meso-NH coupled to a detailed chemical scheme representing the gaseous and aqueous phases. This spatial scale allow to explicitly represent the spatial and temporal characteristics of turbulent structures. Thermals in the boundary layer are identified by a conditional sampling based on a radioactive-decay passive scalar. The turbulent transport influence on the redistribution of chemical species depends on the chemical lifetimes of these species. Spatial segregation is created within the convective boundary layer that increases or decreases the mean reaction rates between compounds. AMMA campaign field study, and more recently DACCIWA, are used to define dynamical and chemical forcing of two simulated environments. The first one is representative of a biogenic environment dominated by natural emissions of VOC. The second reproduces a moderately polluted typical urban area of the Guinean Gulf (Cotonou in Benin). For the sake of simplicity, simulations analysis are limited to the chemical reaction between isoprene and OH in the biogenic case, and the reaction between C>2 aldehydes and OH in the anthropogenic case. The convective boundary layer influence is studied at thermal and domain scale. This makes the connection with coarse resolution models for which a hypothesis of perfect and immediate mixing is made, neglecting the spatial variability of chemical species within a grid cell. The first results are based on the gaseous phase only. Cloudy development in the convective boundary layer only affects the vertical transport of chemical species. The simulations show that thermals are preferential reaction zones where the chemical reactivity is the highest. The top of the boundary layer is the region characterized by the highest calculated segregation intensities but of the opposite sign in both environments. In the biogenic environment, the inhomogeneous mixing of isoprene and OH in this zone leads to a maximum decrease of 30% of the mean reaction rate. In the anthropogenic case, the effective rate constant for OH reacting with aldehydes is 16% higher at maximum than the averaged value. The OH reactivity is higher by 15 to 40% inside thermals compared to the surroundings depending on the chemical environment and time of the day. Because thermals occupy a small fraction of the simulated domain, the impact of turbulent motions on the domain-averaged OH total reactivity reaches a maximum 9% decrease for the biogenic case and a maximum of 5% increase for the anthropogenic case. LES simulations including the aqueous reactivity reveal a significant decrease in OH mixing ratios associated to the presence of clouds. Consequently, isoprene and C>2 aldehydes mixing ratios increase at these altitudes.
492

Des systèmes amorceurs hautes performances pour les photopolymérisations radicalaires, cationiques ou radicalaires contrôlées / Initiators systems high performance for radical, cationic or radical controlled photopolymerization

Telitel, Sofia 24 September 2015 (has links)
Des photoamorceurs construits sur une chimie radicalaire originale sont développés. Les photopolymères présentent des avantages écologiques (pas de COV) et économiques. Ils sont utilisés dans les adhésifs, les encres, les revêtements, l’optique… Une première étude est réalisée sur la photopolymérisation radicalaire (FRP) en présence d’organoboranes. Sous l’action de la lumière, des radicaux boryles sont formés. Ces composés convertissent des radicaux peroxyle (stables) en radicaux boryles très réactifs sous air. Ils permettent ainsi une polymérisation radicalaire en milieu aéré. Avec l’ajout de colorant, la photopolymérisation a lieu sous lumière visible.Une seconde étude est menée sur la photopolymérisation cationique (FRPCP). Des sources d’irradiation douces (lampe halogène, LED,…), peu énergivores et peu coûteuses sont employées. Des composés photosensibles ayant de fortes propriétés d’absorption dans le visible sensibilisent les sels d’iodonium. Cette décomposition permet d’amorcer la polymérisation cationique sous faible intensité lumineuse.Enfin, la polymérisation radicalaire contrôlée/vivante induite par de la lumière UV et visible est présentée. Deux modes de polymérisation contrôlée sont discutés : la NMP2 (Nitroxide Mediated PhotoPolymerization) et l’ATRP2 (Atom Transfer Radical PhotoPolymerization). En NMP2, les alcoxyamines ont la particularité de se réactiver sous irradiation lumineuse. En ATRP2, de nouveaux complexes d’iridium et de fer ayant de bonnes propriétés d’absorption dans le visible sont employés comme photocatalyseurs. Les résultats montrent un caractère contrôlé/vivant lors de la photopolymérisation du MMA. / Photoinitiators constructed on an original radical chemistry are developed. Photopolymers have ecological advantages (no VOCs) and economic. They are used in adhesives, inks, coatings, optical...A first study is carried out on the radical curing (FRP) in the presence of boron molecules. Under light irradiation, boryls radicals are formed. These compounds convert peroxyl radicals (stable) in boryls radicals highly reactive under air. They allow a radical polymerization in aerated medium. With the addition of dye, the photopolymerization is carried out under visible light.A second study was conducted on the cationic curing (FRPCP). Soft radiation sources (halogen lamp, LED, ...), energy efficient and inexpensive are used. Photosensitive compounds having high absorption properties in the visible sensitize iodonium salts. This decomposition allows initiating the cationic polymerization under low light intensity.Finally, controlled/living radical polymerization induced by UV and visible light is presented. Two controlled polymerization methods are discussed: NMP2 (Nitroxide Mediated Photopolymerization) and ATRP2 (Atom Transfer Radical Photopolymerization). In NMP2, alkoxyamines have the particularity to be reactivated under light irradiation. In ATRP2, new iridium complexes and iron having good absorption properties in the visible range are used as photocatalysts. The results show a controlled/living character during the photopolymerization of MMA.
493

Processo de recuperação cirúrgica em pacientes submetidos à prostatectomia radical: estudo longitudinal de variáveis sociodemográficas, clínicas e psicológicas / Surgical recovery process in patients submitted to radical prostatectomy: longitudinal study of sociodemographic, clinical and psychological variables

Romanzini, Adilson Edson 20 June 2017 (has links)
O processo de recuperação cirúrgica pode ser precoce, esperado ou prejudicado, conforme estado de saúde do individuo e do próprio ato cirúrgico, que determinam a perspectiva de bem-estar e qualidade de vida, tendo neste período como parâmetro o alcance de condições superiores ou equivalentes as que os pacientes apresentavam no período pré-operatório. O objetivo deste estudo foi caracterizar variáveis sociodemográficas, clínicas e psicológicas e identificar os fatores preditivos para o bem-estar e qualidade de vida nos diferentes períodos de observação (0, 30, 90, 180 e 360 dias). Trata-se de um estudo longitudinal, de 120 participantes submetidos à prostatectomia radical, por período de até 12 meses. Foram utilizados questionários para caracterização do participante e para avaliação clínica e os instrumentos: Escala Visual Analógica de Dor, Inventário de Estratégias de Coping, Escala Hospitalar de Ansiedade e Depressão, Escala de Satisfação com o Suporte Social, Escala de Satisfação Conjugal, Escala de Bem-Estar Subjetivo e o Expanded Prostate Cancer Index. Os dados foram descritos por períodos e analisados pelo modelo linear de efeitos mistos. Os principais resultados na descrição dos dados apontaram que as médias dos escores de dor variaram de 0,63 a 2,42. As médias de enfrentamento focado no problema variaram de 1,20 a 1,67, sendo mais evidente em T0, T1, T2 e T3 em relação ao enfrentamento focado na emoção, que teve variação de 1,20 a 1,48. As médias de ansiedade variaram de 4,42 a 6,01 e a depressão de 3,59 a 4,24, sendo as de ansiedade ligeiramente superiores às de depressão na maioria dos períodos, exceto em T4. A satisfação com o suporte social variou com médias de 3,81 a 3,97. A satisfação conjugal variou de 1,73 a 1,99, de modo que, a maioria dos participantes não estava satisfeita com o relacionamento conjugal. Já o bem-estar subjetivo apresentou médias de 2,59 a 2,77, sendo a satisfação com a vida e o afeto positivo os principais domínios. Notou-se que o bem-estar subjetivo se apresentou estável nos períodos quando comparado com T0. Já a qualidade de vida variou com médias de 68,69 a 81,80. No período T0, os participantes apresentaram menores médias quanto à função sexual e incômodo urinário. Entretanto, nos períodos T1, T2, T3 e T4, as menores médias foram em relação à função sexual e incontinência urinária. Quando comparado com T0, a qualidade de vida foi inferior em todos os períodos no pós-operatório. Na análise de métodos mistos, o tempo de cirurgia, enfrentamento focado no problema, ansiedade e satisfação conjugal foram preditores de bem-estar subjetivo, entretanto, as variáveis idade, raça/cor, tempo de anestesia, dor, depressão e satisfação com o suporte social não foram preditoras para o bem-estar subjetivo. Já os preditores de qualidade de vida foram as variáveis dor, depressão, enfrentamento focado na emoção, ansiedade e satisfação conjugal, entretanto, a idade, raça/cor, tempo de anestesia e satisfação com o suporte social não foram preditoras para a qualidade de vida. Os resultados apresentados contribuem para a compreensão do processo de recuperação cirúrgica de participantes submetidos à prostatectomia radical / The surgical recovery process can be early, expected or impaired, according to the individual\"s health condition and the surgery, which determine the perspectives of wellbeing and quality of life. In this period, the achievement of conditions higher or equivalent to what the patients presented in the preoperative period serves as the parameter. The objective in this study was to characterize sociodemographic, clinical and psychological variables and to identify the predictive factors of wellbeing and quality of life in the different observation periods (0, 30, 90, 180 and 360 days). A longitudinal study was undertaken of 120 participants submitted to radical prostatectomy over a 12-month period. Questionnaires were used to characterize and clinically assess the participants, as well as the following instruments: Visual Analogue Pain Scale, Ways of Coping, Hospital Anxiety and Depression Scale, Satisfaction with Social Support Scale, Scale of Marital Satisfaction, Subjective Wellbeing Scale and the Expanded Prostate Cancer Index. The data were described per period and analyzed using the linear mixed effects model. The main results in the description of the data appointed that the mean pain scores ranged between 0.63 and 2.42. The mean problemfocused coping scores varied between 1.20 and 1.67, being clearer in T0, T1, T2 and T3 than emotion-focused coping, which varied between 1.20 and 1.48. The mean anxiety scores ranged between 4.42 and 6.01 and depression between 3.59 and 4.24, the former slightly surpassing the latter in most periods, except in T4. The satisfaction with social support varied with averages between 3.81 and 3.97. Marital satisfaction ranged between 1.73 and 1.99, showing that most participants were not satisfied with the marital relationship. Subjective wellbeing presented mean scores between 2.59 and 2.77, the main domains being satisfaction with life and positive affect. As observed, subjective wellbeing was stable in the periods when compared to T0. Quality of life, then, varied with averages between 68.69 and 81.80. In period T0, the participants presented lower averaged for the sexual function and urinary discomfort. In periods T1, T2, T3 and T4, on the other hand, the lowest averages were related to the sexual function and urinary incontinence. When compared to T0, the quality of life was lower in all postoperative periods. In the mixed methods analysis, the length of surgery, problem-focused coping, anxiety and marital satisfaction were predictors of subjective wellbeing, while age, race/color, length of anesthesia, pain, depression and satisfaction with social support did not serve as predictors of subjective wellbeing. The predictors of quality of life were pain, depression, emotion-focused coping, anxiety and marital situation, while age, race/color, length of anesthesia and satisfaction with social support did not serve as predictors for quality of life. The results presented contribute to understand the surgical recovery process of participants submitted to radical prostatectomy
494

Azido- and Triazolyl-modified Nucleoside/tide Analogues: Chemistry, Fluorescent Properties, and Anticancer Activities

Wen, Zhiwei 25 June 2018 (has links)
Two classes of C5 azido-modified pyrimidine nucleosides were synthesized and explored as radiosensitizers. The 5-azidomethyl-2'-deoxyuridine (AmdU) was prepared from thymidine and converted to its cytosine counterpart (AmdC). The 5-(1-azidovinyl) modified 2'-deoxyuridine (AvdU) and 2'-deoxycytidine (AvdC) were prepared employing regioselective Ag-catalyzed hydroazidation of 5-ethynyl pyrimidine substrates with TMSN3. AmdU and AmdC were converted to 5'-triphosphates AmdUTP and AmdCTP, and incorporated into DNA-fragments via polymerase-catalyzed reaction during DNA replication and base excision repair. Radiation-mediated prehydrated electrons formed in homogeneous aqueous glassy (7.5 M LiCl) systems in the absence of oxygen at 77 K led to site-specific formation of π-type aminyl radicals (RNH•) from AmdU, AmdC, AvdU, and AvdC. The ESR spectral studies and DFT calculations showed RNH• undergo facile conversion to thermodynamically more stable σ-type iminyl radicals, R=N•. For AmdU, conversion of RNH• to R=N• was bimolecular involving α-azidoalkyl radical as intermediate; however, for AvdU, RNH• tautomerized to R=N•. Our work provides the first evidence for the formation of RNH• attached to C5 position of azidopyrimidine nucleoside and its facile conversion to R=N• under reductive environment. These aminyl and iminyl radicals can generate DNA damage via oxidative pathways. The azido-nucleosides were successfully applied as radiosensitizers in EMT6 cancer cells in both hypoxic and normoxic conditions. To explore the generation and reactivity of 2'‑deoxyguanosin-N2-yl radical (dG(N2-H)•) postulated to generate from guanine moiety towards •OH, 2-azido-2'-deoxyinosine (2-N3dI) was prepared by conversion of 2-amino group in protected dG into 2-azido via diazotization with tert-butyl nitrite followed by displacement with azide and deprotection. The investigation of dG(N2-H)• generated from 2-N3dI and its subsequent reactions using ESR will be discussed. Cycloaddition between 5-ethynylpyrimidine or 8-ethynylpurine nucleosides and TMSN3 in the presence of Ag2CO3, CuI, or CuSO4/sodium ascorbate provided N-unsubstituted 1,2,3-triazol-4-yl analogues of the parental DNA bases (i.e. 5-TrzdU, 5‑TrzdC, 8-TrzdA, and 8-TrzdG). These novel triazolyl nucleosides showed excellent fluorescent properties: 8-TrzdA exhibits the highest quantum yield (ΦF) of 44% while 8‑TrzdG had ΦF of 9%. The 5-TrzdU and 5-TrzdC showed a large Stokes shift of ~110 nm. The application of these fluorescent nucleosides to cell imaging and DNA modifications will also be discussed.
495

Laser flash photolysis studies of some gas phase reactions of atmospheric interest

Zhao, Zhijun 20 August 2009 (has links)
Radical reactions play central roles in regulating regional air quality and global climate. Some potentially important gas phase radical reactions are being investigated in this research project, including Cl reactions with acetone, butanone, 3-pentanone, pyridine, and dimethyl selenide (DMSe), HO2 complex formation and dissociation with formic and acetic acids, and reactive and non-reactive quenching of O(1D) by the potent greenhouse gases SO2F2, NF3, and SF5CF3. The involved radicals are generated by laser flash photolysis (LFP). Temporal profiles of either the radical reactant or a product are monitored in "real time" using atomic resonance fluorescence spectroscopy (RF), time-resolved UV-visible absorption spectroscopy (TRUVVAS), or tunable diode laser absorption spectroscopy (TDLAS), allowing kinetic and mechanistic information of these reactions to be obtained. These studies provide new knowledge of the investigated radical reactions and facilitate a better understanding of their significance in atmospheric chemistry.
496

Dawn of the radicals : The connection between economic growth and political radicalism

Wickström, David January 2015 (has links)
This thesis explores how economic performance, measured as real GDP-growth per capita, affects the vote share of parties which relies on radical ideological platforms. Using a fixed effect model with panel data, based on real electoral outcomes of 18 western European democracies, the result reveals an ambiguous reality. The overall conclusion implies that low growth rates benefit the electoral success of radical-right parties and holds for robustness checks. No solid evidence of the relationship is found on the radical-left side.The result further reveals that the individuals decision to vote radical is relative more affected by the ongoing business cycle trend between the elections rather than sudden changes close to the election day. The relationship also appears to be stronger among nations of southern Europe.
497

Sverigedemokraterna: Ett radikalt högerpopulistiskt parti? : En idealtypsanalys av Sverigedemokraternas principprogram (2011)

Avetisova, Anastasia January 2015 (has links)
The Sweden Democrats has become the third largest party in Sweden after the parliamentary elections in 2014. Ever since the party was founded in 1988, debates regarding the party’s policy has been of great interests but also the party’s ideological affiliation whether to classify it as a populist radical right party or not. Furthermore, many scientists have arrived at the conclusion that the Sweden Democrats should be seen as a populist radical right party. This conclusion makes it interesting to further investigate what ideological affilitation the party should identify itself with since the party itself argues to be a social conservative party with a nationalist ethos. With this in mind, the purpose of this study is to examine if the party has populist radical right fundamentals in its recent policy program through the use of the method idea analysis and through the use of creating an ideal type of the theory populist radical right. In addition, it has thus been possible to confirm or to deny the Sweden Democrats as a populist radical right party. The result of this thesis has shown that the policy program does consist of populist radical right elements. Hence, it has been concluded that the Sweden Democrats should be categorized as a populist radical right party.
498

Enhancement of menadione cytotoxicity by bicarbonate: redox cycling and a possible role for the carbonate radical in quinone cytotoxicity

Aljuhani, Naif Saad Unknown Date
No description available.
499

Le conflit dans la communauté pluraliste chez Chantal Mouffe

Gagnon-Tessier, Louis-Charles January 2008 (has links)
Mémoire numérisé par la Division de la gestion de documents et des archives de l'Université de Montréal
500

The role of radicals supplied directly and indirectly on ignition

Kim, Jaecheol 12 January 2015 (has links)
The ignition process is a critical consideration for combustion devices. External energy transfer to the combustor is required for ignition in common combustion systems. There are many ways to deposit energy into the flow but a standard method is a spark discharge because it is simple, compact, and reliable. Sparks can be categorized as either inductive or capacitive sparks that use a coil or an electrical resonance circuit with capacitor, respectively, to amplify the voltage. The creation of a successful ignition event depends on the spark energy deposited into the flow, the initial composition, pressure, temperature, turbulence level of flow etc. The deposited energy by the spark into the flow is critical for estimation of initial energy available for ignition of the mixture. Therefore, the electrical characteristics of the sparks were investigated under various flow conditions. Then measurements of deposited energy into the flow were conducted using a very accurate experimental procedure that was developed in this research. The results showed considerable electric energy losses to the electrodes for the relatively long, inductive sparks. However, the short, capacitive spark deposits electric energy into the flow with minimal loss (above 90% deposition efficiency). In addition, the characteristics of inductive spark are affected by flow velocity and by the existence of a flame. However, variations in the flow conditions do not affect the characteristics of the capacitive spark such as voltage-current time trace and energy deposition efficiency. Two ignition systems using above mentioned two spark types were developed. First, the capacitive spark energy was directly deposited into the premixed flow. Most researchers have not concentrated on the early initiation process but on the flame growth. Therefore, the generated kernel formed by the energy deposition was observed and characterized using optical methods, immediately following the spark. In addition, the mixing effect for this ignition kernel with surrounding gas was simulated using a numerical method. Based on the time trace of the OH* chemiluminescence, the reaction starts with the discharge and it is continuous until combustion begins. This means that in the presence of a high density spark in premixed flow, there exists no traditional delay as defined by other researchers for auto ignition. A simple Radical Jet Generator (RJG) was developed that is able to ignite and stabilize a flame in a high-speed flow. The inductive spark initiates the combustion in the RJG chamber. The RJG then injects the partially-burned products carrying large amounts of heat and radicals into a rapidly moving flammable main stream. Then it ignites and stabilizes a flame. The RJG requires low levels of electrical power as long as the flow velocity is relatively low since most of the radicals are produced by the incomplete combustion in its chamber. The importance of radicals was analyzed by RJG experiments and numerical methods. The reaction zone for RJG using a rich mixture was located both inside and outside of the RJG chamber. Therefore, the RJG using a rich mixture performed better in the ignition and stabilization of combustion in the main flow. According to an analysis using the CHEMKIM simulation software combined with the San Diego chemical mechanism, the RJG jet resulting from a rich mixture contains more radicals and intermediates than that produced by a lean mixture for the same sensible enthalpy. In addition, the burned gas contains less radicals and intermediates than the partially burned gas. If the RJG is operating with a high speed main flow, the flow rate through the RJG chamber must be increased to allow the radical jet to penetrate well into the rapid flow due to their higher injection velocity. Unfortunately, this leads to unsteady combustion in the RJG, which results in the pulsation of the radical jet. This reduces the number of radicals injected into the main flow. To investigate this operating condition, special attention was focused on four possible factors: unburned reactant pockets caused by motion of the spark channel, spark frequency, flame propagation speed and ignition delay. It was shown that the unsteadiness is affected by the flame speed and ignition delay because the frequency of pulsation in the chamber is highly dependent on the equivalence ratio. In addition, the interaction between the RJG operation and the combustion dynamics in the main combustor was documented. The acoustic pressure oscillations in the main combustor were suppressed when the RJG jet was turned on because the reaction region is relocated by the operation of the RJG.

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