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Incineration of waste materials has become a common way to handle a worldwide increase of produced waste materials. The problem with waste as fuel is that the material is not homogeneous and include a mixture of fossils and renewables. The fossil part ends up in an emission of fossil carbon dioxide in a combustion process, which is included in the emissions trading system. However, since waste material varies a lot in composition depending on the time of the year, origins, etc. it is preferable to have a method for real-time measurement of the fossil share of combusted waste. No real-time measurement technologies are available today which is the reason to investigate if near-infrared (NIR) spectroscopy could be a potential solution. An artificial mixture of refused derived fuel has been used to investigate the possibilities of NIR for prediction of the fossil share in waste material. The fossil share is assumed to be equal to the content of plastic material with an origin of oil products. Mixtures with different plastic content are scanned by the NIR instrument to obtain individual absorption spectra. A Partial least square (PLS) regression model is created on measured spectra and known content of plastics. The best model for the prediction on new spectral data using one of four measured replicates is a PLS model preprocessed with Savitzky-Golay smoothing that gives an R-square value of 0,782. If the prediction is done, depending on a delimitated wavenumber interval and an average of all four replicates is the best model instead of a PLS model pre-processed with standard normal variate without seven outliers that have an R-square value of 0,81. R-square value is the coefficient of determination which has been used to figure out the best model. An R-square value above 0,65 are recommended for process modelling, where 1 is the highest possible value.

Implication de l’oxygénation cérébrale dans les limitations à l’exercice musculaire des personnes non-entraînées et sportifs d’endurance. L’objectif général de ce travail était de déterminer si l’oxygénation cérébrale était un facteur de la limitation à l’exercice de type aérobie. Dans un premier temps, nous nous sommes attachés à étudier le rôle de l’oxygénation cérébrale mesurée par la Spectroscopie dans le proche Infra-Rouge (NIRS) dans la limitation de l’exercice progressif maximal en rampe. Nous avons montré l’existence d’un seuil de déclin de l’oxygénation cérébrale associé au point de compensation respiratoire (RCP). L’amélioration de la performance avec une supplémentation d’O2 était liée au décalage de ce seuil à de plus hautes intensités d’exercice chez des sujets actifs (étude 1). Dans un second temps, nous avons montré que ce seuil de déclin de l’oxygénation, retrouvé aussi chez des sportifs entraînés en endurance apparaîssait à de plus hautes intensités d’exercice que chez des sujets non-entraînés (étude 2). Enfin, nous avons déterminé l’impact de l’hypoxémie artérielle induite par l’exercice (HIE) des sportifs d’endurance sur l’oxygénation cérébrale au cours d’un exercice maximal en rampe et d’un exercice de temps limite à charge constante. Nous avons ainsi montré que l’oxygénation cérébrale était augmentée avec la HIE suggérant un effet compensatoire à l’hypoxémie artérielle au cours de l’exercice progressif maximal en rampe. Ceci, n’existait pas au cours de l’exercice de temps limite ne supportant pas l’implication de l’oxygénation cérébrale dans ce type d’exercice (étude 3). Ces travaux ont donc mis en évidence l’implication de l’oxygénation cérébrale dans la limitation de l’exercice maximal en rampe chez des sujets actifs et des sportifs entraînés en endurance présentant ou pas une HIE. Toutefois, elle ne semble pas être un facteur majeur de limitation de l’exercice de temps limite. / Involvement of cerebral oxygenation in muscular exercice limitation in untrained and trained endurance men. A decrease in oxygen availability in the brain could be a physiological mechanism limiting aerobic fitness. We first studied the role of cerebral oxygenation measured by Near Infra-Red Spectroscopy (NIRS ) in maximal cycle ramp exercise limitation. We showed a cerebral oxygenation threshold decline associated with respiratory compensation point (RCP). This threshold appeared for higher exercise intensities -related to performance improvement with hyperoxia in untrained endurance men (study 1). Secondly , we showed that the cerebral oxygenation threshold in athletes occurred for higher sub-maximal exercise intensities than untrained (study 2). Finally , we determined the involvement of exercise-induced arterial hypoxemia (EIH) in endurance athletes on cerebral oxygenation during maximal cycle ramp exercice and exercice time to exhaustion. We showed that cerebral oxygenation was improved by EIH suggesting a compensatory effect of EIH during the maximal cycle ramp. This did not occur during exercise time to exhaustion, and does not support the involvment of cerebral oxygenation in this type of exercise (study 3). This work has therefore highlighted the involvement of cerebral oxygenation in maximal cycle ramp exercice limitation in untrained and trained endurance men with or without EIH. However, it was unlikely been the major factor limiting the exercise time to exhaustion.

Thesis (PhD(Agric) (Horticulture))--University of Stellenbosch, 2011. / Includes bibliography. / ENGLISH ABSTRACT: Plums with good taste, aroma and eating quality lead to repeat purchases and sustained demand. Taste includes non-volatile compounds, e.g. sugars and acids, and has been well researched to meet the consumers’ preferences. Plum aroma, however, has not enjoyed the same attention. Limited literature is available on the aroma of Japanese plums and none could be found on the effects of relatively long cold storage on the profiles. The main aim of this study is to investigate the changes in aroma compounds of Japanese plums throughout maturation and ripening and the effects of commercial cold storage regimes. Near infra-red (NIR) spectroscopy was also evaluated as a non-destructive method to determine plum quality parameters aimed at minimising sample variability. In Paper 1, NIR spectroscopy was used to develop prediction models for total soluble solid (TSS), total acidity (TA), sugar-to-acid ratio, firmness and weight in three cultivars (Pioneer, Laetitia and Angeleno) and a multi-cultivar model. Samples were collected for seven consecutive weeks and repeated over two seasons. TSS results showed excellent predictability (R2 = 0.817-0.955; RMSEP= 0.453-0.610 % Brix) but the TA models did not perform well. The sugar-to-acid ratio models had results comparable to that of TSS. Both the firmness and weight models had acceptable results. The models of ‘Pioneer’ and ‘Laetitia’ had a better predictability capacity than the ‘Angeleno’ model. Although the multi-cultivar models outperformed the single cultivar models on R2 values it had higher prediction errors. The robustness of all the TSS, TA and firmness models is high in terms of seasonality, range and cultivar. Papers 2 and 3, the main focus of the study, are concerned with the aroma profile dynamics of Japanese plums. HS-SPME was used in both papers to extract the aroma compounds followed by GC-TOFMS for separation and identification. In Paper 2, the aroma volatile compounds of three cultivars (Pioneer, Laetitia and Angeleno) were determined for a seven week period including samples from three maturity stages (immature, harvest and tree-ripe). A total of 35 compounds were identified of which ten were generic. Each cultivar had five unique compounds resulting in different aroma profiles for each of the maturity stages and distinct separation patterns using discriminant analysis. The study was extended in Paper 3 where the aroma volatile compounds of six cultivars (Pioneer, Sapphire, Laetitia, Songold, Larry Anne and Angeleno) and one plumcot (Flavor King) were determined at three functional stages (commercial harvest, tree-ripe fruit and cold stored fruit). A total of 62 compounds were identified and classified into three groups (‘unique’ (31), ‘generic’ (11) and ‘frequent’ (20)) based on their frequency of occurrence. The aroma profiles of ‘Larry Anne’ and ‘Flavor King’ are the most affected by cold storage conditions and ‘Pioneer’ appears to be the least affected. All the cultivars have significantly different aroma profiles at all three of the functional stages with ‘Sapphire’, ‘Larry Anne’ and ‘Flavor King’ showing the largest differences. ‘Flavor King’, a plumcot, presented a ripe aroma profile that was much diverged from that of the true plums. / AFRIKAANSE OPSOMMING: Pruime met ‘n goeie smaak, aroma en eetkwaliteit lei tot herhaalde verkope en volhoubare aanvraag. Smaak sluit die nie-vlugtige stowwe (suikers en sure) in en is goed nagevors om die verbruikersvoorkeure te bevredig. Pruim aroma het egter nie dieselfde aandag geniet nie. Daar is beperkte literatuur beskikbaar wat handel oor die aroma van Japanese pruime en geen kon gevind word oor die effekte van lang koelopberging op die aromaprofiele nie. Die hoof doel van hierdie studie is om die veranderinge in die aromatiese komponente van Japanese pruime te ondersoek tydens die volwassewording- en rypwordingsprosesse asook die effekte van kommersiele koelopberging. Naby infrarooi (NIR) spektroskopie is ook geevalueer as ‘n nie-destruktiewe manier om pruim kwaliteitsparameters te bepaal met die doel om monstervariasie te beperk. In Artikel 1 is NIR spektroskopie gebruik om voorspellingsmodelle vir totale oplosbare suikers (TOS), totale suur (TS), suiker-tot-suur verhouding, fermheid en gewig te bepaal in drie kultivars (Pioneer, Laetitia en Angeleno) asook ‘n multi-kultivar model. Monsters is vir sewe opeenvolgende weke versamel en herhaal oor twee seisoene. TOS resultate toon uitstekende voorspelbaarheid (R2 = 0.817-0.955; RMSEP= 0.453-0.610 % Brix) maar TS modelle het egter nie so goed gevaar nie. Die suiker-tot-suur verhoudingsmodelle se resultate was vergelykbaar met die van TOS. Beide die fermheid- en gewigsmodelle het aanvaarbare resultate opgelewer. Die modelle vir ‘Pioneer’ en ‘Laetitia’ het ‘n beter voorspelbaarheidskapasiteit getoon as die van ‘Angeleno’. Alhoewel die multi-kultivar model beter presteer het as die enkel kultivar modelle op die R2-waardes was daar meer voorspellingsfoute. Hoe robuustheid is gevind i.t.v. seisoene, datagrense en kultivar vir al die TOS, TA en fermheidsmodelle. Artikels 2 en 3, die fokuspunt van die studie, handel oor die dinamika van die aromaprofiel van Japanese pruime. HS-SPME is in beide artikels gebruik on die aromatiese verbindings te ekstraeer gevolg deur GCTOFMS vir skeiding en identifikasie. In Artikel 2 is die aromatiese stowwe van drie kultivars (Pioneer, Laetitia en Angeleno) bepaal vir sewe opeenvolgende weke en sluit monsters van drie volwassenheidsstadiums in (onvolwasse, oes en boom-rypgemaakte pruime). ‘n Totaal van 35 verbindings is geidentifiseer waarvan tien as generies beskou kan word. Elke kultivar het vyf unieke komponente gehad en het gelei tot verskillende aromaprofiele vir elk van die volwassenheidsstadiums en diverse skeidingspatrone tydens die gebruik van diskriminant analise. Die studie is uitgebrei in Artikel 3 waartydens die aromatiese vlugtige stowwe van ses kultivars (Pioneer, Sapphire, Laetitia, Songold, Larry Anne en Angeleno) en een plumcot (Flavor King) bepaal is tydens drie funksionele stadiums (oes, boom-rypgemaak en koelopgebergde pruime). ‘n Totaal van 62 verbindings is geidentifiseer en in drie groepe geklassifiseer (‘uniek’ (31), ‘generies’(11) en ‘gereeld’ (20)) gebaseer op voorkomsfrekwensie. Die aromaprofiele van ‘Larry Anne’ en ‘Flavor King’ is die meeste deur die koelopberging geaffekteer en ‘Pioneer’ die minste. Al die kultivars het kenmerkend verskil t.o.v. hul aromaprofiele in al drie die funksionele groepe en ‘Sapphire’, ‘Larry Anne’ en ‘Flavor King’ het die grootste verskille getoon. ‘Flavor King’, die plumcot, het ook ‘n ryp aromaprofiel gehad wat baie van die van die egte pruime verskil het.

The synthesis, photophysical and electronic properties of a series of novel boron containing fused and ladder type donor-acceptor (D-A) oligomers and polymers are reported. The synthesis was achieved through coordination of the basic functionality of the ubiquitous benzothiadiazole acceptor unit onto a boron Lewis acid followed by an electrophilic aromatic borylation resulting in the formation of fused and ladder type structures (termed borylative fusion). The novel C,N-chelated borane structures disclosed herein are a new member of a large family of tetra-coordinate organoboron compounds that are used for the construction of highly emissive materials. Upon borylation large bathochromic shifts in the absorption and fluorescence spectra were observed, DFT and cyclic voltammetry demonstrate that this is a result of a significant reduction of the LUMO energy levels whist the HOMO energy levels remains relatively unperturbed. These large bathochromic shifts lead to materials that show far red/NIR emission in the solid state with absolute quantum yields of up to 44%. Furthermore, the frontier molecular orbital energy levels of these fused structures can be modulated through judicious selection of the exocyclic boron substituents. These novel borocycles also proved stable to a range of cross-coupling conditions which facilitated further modulation of the frontier molecular orbitals and emissive properties. Borylative fusion was also applicable to D-A conjugated polymers, this represents a facile post-polymerisation functionalisation that is an effective method of modulating the photophysical properties of D-A conjugated polymers. Solution processed OLEDs with far red/NIR electroluminescence (EL) were fabricated from these materials. These devices showed good external quantum efficiency values (EQE) for the far red/NIR region of the electromagnetic spectrum (EQE > 0.4 % for maximum EL > 700 nm).

La maladie de Parkinson est la seconde pathologie neurodégénérative la plus fréquente après la maladie d’Alzheimer. Elle se manifeste par une mort progressive et continue des neurones dopaminergiques de la voie nigro-striée, accompagnée de troubles moteurs et non moteurs lourdement handicapants. La maladie de Parkinson touche près de 6,3 millions de personnes dans le monde, avec une répartition homogène sur l’ensemble de la planète. Il existe plusieurs thérapeutiques permettant de diminuer les symptômes des malades, dont les plus efficaces sont la dopa-thérapie et la stimulation cérébrale profonde. Toutefois, à ce jour, aucune stratégie visant à protéger les neurones dopaminergiques de la dégénérescence n’a démontré son efficacité chez l’humain. En parallèle, un nombre grandissant d’études montre le potentiel cytoprotecteur d’une illumination proche infrarouge. Récemment, plusieurs études ont démontré le potentiel neuroprotecteur de cette gamme de lumière sur des modèles rongeurs de la maladie de Parkinson. L’objectif du présent travail est de confirmer ce potentiel et d’optimiser son efficacité afin de préfigurer l’essai clinique à venir. Pour ce faire, avec les modèles MPTP souris et 6-OHDA unilatéral rat, nous avons étudié la faisabilité d’une illumination intracérébrale chronique, l’influence de la longueur d’onde, de la fenêtre temporelle de traitement (pré-, post-traitement), de la quantité globale d’énergie optique apportée (continu vs discontinu, nombre de flashs lumineux, énergie d’un seul flash), de la durée d’un flash et de la puissance optique appliquée sur l’efficacité thérapeutique. Nous démontrons ici la faisabilité d’une illumination intracérébrale chronique et son potentiel neuroprotecteur. Nous montrons par ailleurs que les longueurs d’onde 670 et 810 nm protègent toutes deux les neurones dopaminergiques dans nos modèles d’étude. Nous montrons une mise en place rapide des mécanismes de protection (< 20 min), et un maintien dans le temps pendant au moins 48 heures. De plus, nous observons qu’une illumination discontinue est préférable à une illumination continue. La quantité globale d’énergie optique appliquée semble ne pas avoir de rôle significatif sur l’efficacité du traitement. En revanche, il existe un seuil bas pour la puissance optique, qui semble régie par un effet « tout-ou-rien ». L’efficacité thérapeutique est également liée à la durée d’un flash lumineux, par « un effet en cloche », Tous ces résultats sont en adéquation avec la littérature scientifique qu’ils confirment et complètent. Couplés aux travaux sur primates non humains de mon équipe d’accueil, ils serviront de base de travail à la conception du futur essai clinique. / Parkinson’s disease is the second most common neurodegenerative disease, after Alzheimer disease. It is characterized by a slow, continuous death of dopaminergic neurons in the nigrostriatal pathway, followed by severe motor and non-motor symptoms. Parkinson’s disease affects 6.3 million peoples, with a homogeneous distribution worldwide.There are several symptomatic strategies applied in clinic, such as the dopa-therapy (gold standard) and the deep brain stimulation. However, theses therapeutical approaches are not neuroprotective. Indeed, to date, there is no strategy able to effectively slow or rescue the course of the disease. Alternatively, a growing number of studies show the cytoprotective potential of a near infrared illumination. Recently, several studies showed the neuroprotective potential of these wavelengths in rodent models of Parkinson disease.The aim of this work is to confirm and optimize the efficacy of a near infrared treatment in Parkinson’s disease, as the first step for the future clinical trial.We used the MPTP mice and the 6-OHDA unilateral rat models to assess the feasibility and the effectiveness of an intracerebral chronical illumination. We also measured the influence of the wavelength, the time window (pre-, post-treatment), the global optical energy delivered (continuous vs discontinuous, number of flashs, energy of one flash), the duration of one flash and the optical power on the therapeutical efficacy.We demonstrate here the feasibility of an intracerebral chronical illumination and its neuroprotective potential. We show that the 670 and 810 nm wavelengths both protect the dopaminergic cells in the rodent models, and produce a quick activation of the protective mechanisms (< 20 min). The neuroprotective effect stays effective at least 48 hours after the illumination. Moreover, we show that a discontinuous illumination seems better than a continuous one. The global optical energy delivered has no significant influence on the efficacy. In contrast, the optical power has an everything-or-nothing effect. The therapeutic efficacy is also flash duration dependent (bell effect).All these results confirm and complete the scientific literature. Together with the work on non-human primates from my team, these results will be useful to design the future clinical trial.

Lanthanide elements display many remarkable and exciting properties which explain their widespread use in a number of very important biomedical tools like efficient MRI contrast agents or luminescent probes for highly sensitive assays of bioanalytes amongst other fields of application. In this context, the aim of the present work was to prepare and characterize lanthanide complexes of two ligands that feature a linear or a macrocyclic chelating unit compactly grafted onto a 1,10-phenanthroline derived moiety (phenDTPA and PhenHDO3A). The ditopic nature of the ligands allows the selective incorporation of a d6 metal ion and a lanthanide one in close proximity. The resulting rigid heterobimetallic supramolecular species show useful properties and constitute potential MRI contrast agents or new luminescent compounds depending on the type of the lanthanide and transition metal ions employed: for example, the selfassembly process of gadolinium(III) chelates around an iron(II) ion brings a remarkable increase of their relaxivity, a key parameter for use in MRI. On the other hand, association of a ruthenium and and a near infrared emitting 4f ion like ytterbium(III) gives mixed d-f structures able to harvest visible light and convert it into near infra-red signal. Visible light luminescent pH probes were also obtained with Eu3+ or Tb3+ phenHDO3A complexes.

Submitted by Aelson Maciera (aelsoncm@terra.com.br) on 2017-05-15T19:57:24Z No. of bitstreams: 1 TeseCOF.pdf: 3178869 bytes, checksum: cfad2da3f19b56d42e09c4a472158572 (MD5) / Approved for entry into archive by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-02-01T10:55:05Z (GMT) No. of bitstreams: 1 TeseCOF.pdf: 3178869 bytes, checksum: cfad2da3f19b56d42e09c4a472158572 (MD5) / Approved for entry into archive by Ronildo Prado (bco.producao.intelectual@gmail.com) on 2018-02-01T10:55:19Z (GMT) No. of bitstreams: 1 TeseCOF.pdf: 3178869 bytes, checksum: cfad2da3f19b56d42e09c4a472158572 (MD5) / Made available in DSpace on 2018-02-01T11:06:54Z (GMT). No. of bitstreams: 1 TeseCOF.pdf: 3178869 bytes, checksum: cfad2da3f19b56d42e09c4a472158572 (MD5) Previous issue date: 2016-06-24 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Type 2 diabetes mellitus (DM) is responsible for quality of life reduction due its negative impact in the physical exercise capacity. The impairment of cardiopulmonary fitness and lower values in oxygen uptake in exercise tests has been associated with factors related with diabetes complications. Phototherapy is a resource largely utilized due it action in biological systems and it may be adjuvant to exercise to improve muscular efficiency and increase aerobic capacity. Thus, the question if this resource may be benefit to populations with DM. Therefore, we proposed a study protocol randomized, double-blind, placebo controlled to evaluate the acute effect of light emitting diode (LED) in cardiorespiratory and hemodynamic adjustments of moderate exercise in cycloergometer, as well as, in lactate and glucose levels pre and post intervention and after exercise in men aged between 45 and 64 years, with DM and health. Then, two studies were performed. In the study 1 it was evaluated the acute effect of phototherapy (LED-150J) in two groups: DM group (DMG) and health group (HG) (n=16 and n=9, respectively). The groups were paired by age and body mass index. The LED reduced significantly the glucose levels in DMG after exercise and do not affect the lactate levels, cardiorespiratory and hemodynamic adjustments of aerobic exercise in both groups. Our results suggest that LED in combination with moderate exercise decrease acutely the glucose levels in adult subjects with DM. The study 2 aimed evaluate the acute effect of two different doses of phototherapy. Participated in this study two groups of men with DM: LED-150J (n=16) and LED-300J (n=17). The LED-150J reduced the levels of glucose after exercise. The LED-300J increased the lactate levels after exercise in effective session compared with placebo. Any doses changed the cardiorespiratory and hemodynamic adjustments. This study demonstrated that the phototherapy with LED using the 300J dose did not improved the parameters studied and the 150J dose improved the glycaemia and should be used in combination with other therapies for the hyperglycemia management in individuals with DM. The general conclusion of this thesis is that our findings suggest that phototherapy associated with moderate physical exercise have therapeutic potential to control glycaemia in DM, however, further studies should be conducted investigating the dose window and dose-response capable to change acutely the cardiopulmonary and hemodynamic adjustments and lactate levels. / O diabetes mellitus tipo 2 (DM) é responsável por redução significativa na qualidade de vida devido ao seu impacto negativo na capacidade de realização de exercícios físicos. A diminuição do condicionamento cardiopulmonar e os menores valores de consumo de oxigênio pico em testes de exercício têm sido associados com múltiplos fatores envolvidos nas complicações do diabetes. A fototerapia é um recurso que tem sido utilizado devido sua ação nos sistemas biológicos, podendo ser um coadjuvante do exercício na melhora da eficiência do trabalho muscular e aumento da capacidade aeróbia. Por isso, levantou-se a questão de que tal recurso poderia beneficiar populações com DM. Assim, foi proposto um protocolo experimental aleatorizado e duplo-cego visando avaliar o efeito agudo da fototerapia com diodos emissores de luz (LED) nos ajustes cardiorrespiratórios e hemodinâmicos ao exercício moderado em cicloergômetro, bem como nas concentrações de lactato e glicose sanguíneas pré e pós intervenção e após o exercício físico em homens com DM e saudáveis, com idade entre 45 e 64 anos. A partir deste protocolo dois estudos foram realizados. No estudo 1 foi avaliado o efeito agudo da fototerapia (LED-150J) em dois grupos: grupo com DM (GDM, n=16) e grupo saudável (GS, n=9). Os grupos foram pareados por idade e índice de massa corpórea. O LED reduziu significativamente as concentrações de glicose no GDM após o exercício em cicloergômetro e não afetou os níveis de lactato e os ajustes cardiorrespiratórios e hemodinâmicos em ambos os grupos. Nossos resultados sugerem que o LED em combinação com o exercício moderado reduz de forma aguda os níveis de glicose em homens adultos com DM. No estudo 2 objetivou-se avaliar o efeito agudo de duas diferentes doses de fototerapia. Participaram desse estudo dois grupos de homens com DM: LED-150J (n=16) e LED-300J (n=17). O LED-150J reduziu as concentrações de glicose após o exercício físico e o LED-300J aumentou os níveis de lactato após o protocolo de exercício na fototerapia efetiva em comparação com a fototerapia placebo. Nenhuma das dosagens avaliadas modificou significativamente os ajustes cardiopulmonares e hemodinâmicos avaliados. Este estudo mostrou que a fototerapia por meio de LED na dosagem de 300J não causou melhora nos parâmetros estudados enquanto a dosagem de 150J melhorou a glicemia, podendo ser utilizada como recurso adjuvante no controle da hiperglicemia em indivíduos com DM. Como conclusão geral, nossos achados sugerem que a fototerapia associada ao exercício moderado tem potencial terapêutico no controle da glicemia do DM, no entanto, mais estudos são necessários para estabelecer a janela terapêutica e a dose-resposta capaz de modificar de forma aguda os ajustes cardiopulmonares e hemodinâmicos, assim como os níveis de lactato. / FAPESP: 2013/08183-7 / FAPESP: 2015/20512-1 / FAPESP: BEPE 2013/07953-3

La limitation optique (LO) est un processus de protection des détecteurs optiques (yeux, caméras…) vis-à-vis des agressions laser. Le développement rapide de ces derniers aux fréquences des télécommunications a encouragé l’ingénierie moléculaire pour la LO dans cette fenêtre spectrale, en particulier à 1500 nm. Un des principaux mécanismes de la LO est l’absorption multiphotonique et plus particulièrement l’absorption à deux photons (ADP). Il s’agit d’un phénomène d’optique non-linéaire du troisième ordre au cours duquel un électron est promu de l’état fondamental vers l’état excité par absorption simultanée de deux photons. De plus, des travaux récents ont mis en évidence que le phénomène de LO peut être exalté par des processus d’absorption à l’état excité (AEE) induits par ADP. Dans ce contexte, cette thèse décrit la synthèse d’une nouvelle famille de chromophores de type aza-dipyrrométhène de bore (Aza-Bodipy), fonctionnalisés par des groupements donneur ou accepteur d’électrons. Ces molécules ont un comportement de limiteur optique sur toute la gamme spectrale voulue, avec un maximum d’efficacité vers 1300 nm. Les résultats ont été interprétés sur la base de deux phénomènes : l’ADP, suivie de l’AEE pour un procédé d’absorption globale à trois photons. Ces deux processus ont été mesurés séparément et des relations structure-activité ont été établies, afin de rationnaliser les données de LO. L’importance du transfert de charge et la superposition spectrale des deux phénomènes sont alors apparues comme les paramètres clefs à optimiser. En vue d’une application dans un dispositif optique réel, il est nécessaire que les chromophores soient incorporés dans un matériau solide, qui peut être poli et transformé. Ainsi, les composés synthétisés ont été insérés avec succès dans une matrice sol-gel. Pour la première fois, des matériaux de qualité optique ont été réalisés, possédant des propriétés de LO dans l’infra-rouge très performantes et meilleures qu’en solution. / The optical power limiting (OPL) is a protection process of detectors (eyes, cameras…) against laser aggression. The rapid development of frequency-tunable pulsed lasers up to telecommunication wavelengths led to the design of new materials for nonlinear absorption in this spectral range, in particular at 1500 nm. Mutiphotonic absorption, such as the two-photon absorption (TPA) is one of the mechanisms involved in the OPL. TPA is a third order nonlinear phenomenon that promotes a molecule to an excited state by the simultaneous absorption of two photons. Moreover, the overall OPL efficiency can be enhanced by excited state absorption (ESA). In this context, this thesis describes the synthesis of a new family of versatile near infra-red dyes, namely aza-borondipyrromethene (Aza-Bodipy) featuring several sites of functionalization by electro-donating or electro-withdrawing moieties. These molecules present the typical behavior of optical limiters at telecommunication wavelengths, with a maximal efficiency around 1300 nm. OPL curves were interpreted on the basis of two phenomena: TPA, followed by ESA for an overall 2+1 photons absorption. These two processes have been measured independently and structure-activity relationships have been established in order to rationalize OPL experiments. The charge transfer effect and the spectral overlap between TPA and ESA are therefore the key parameters. For practical use of OPL functions, it is required for the chromophores to be introduced into a solid material, which enables polishing and other post-processing. Therefore, Aza-Bodipy dyes have been successfully incorporated to a solid matrix using the sol-gel technique. For the first time, optical quality materials have been prepared featuring OPL properties in the infra-red, which are better than the ones in solution.

This study addresses the influence of elevated pressures, fuel type, fuel flow rate and co-flow air on the flame structure and flickering behaviour of laminar oscillating diffusion flames. Photomultipliers, high speed photography and schlieren, accompanied with digital image processing techniques have been used to study the flame dynamics. Furthermore, the effects of pressure on the flame geometry and two-dimensional soot temperature distribution in a laminar stable diffusion flame have been investigated, utilising narrow band photography and two-colour pyrometry technique in the near infra-red region. This study provides a broad dataset on the diffusion (sooty) flame properties under pressures from atmospheric to 16 bar for three gaseous hydrocarbon fuels (methane, ethylene and propane) in a co-flow burner facility.It has been observed that the flame properties are very sensitive to the fuel type and flow rate at elevated pressures. The cross-sectional area of the stable flame shows an average inverse dependence on pressure to the power of n, where n was found to be 0.8±0.2 for ethylene flame, 0.5±0.1 for methane flame and 0.6±0.1 for propane flame. The height of a flame increases firstly with pressure and then decreases with further increase of pressure. It is observed that the region of stable combustion was markedly reduced as pressure was increased. An ethylene flame flickers with at least three dominant modes, each with corresponding harmonics at elevated pressures. In contrast, methane flames flicker with one dominant frequency and as many as six harmonic modes at elevated pressures. The increase in fuel flow rate was observed to increase the magnitude of oscillation. The flickering frequency, however, remains almost constant at each pressure. The dominant flickering frequency of a methane diffusion flame shows a power-law dependence on chamber pressure.It has been observed that the flame dynamics and stability are also strongly affected by the co-flow air velocity. When the co-flow velocity reached a certain value, the buoyancy driven flame oscillation was completely suppressed. The schlieren imaging has revealed that the co-flow of air is able to push the initiation point of outer toroidal vortices beyond the visible flame to create a very stable flame. The oscillation frequency was observed to increase linearly with the air co-flow rate. The soot temperature results obtained by applying the two-colour method in the near infra-red region shows that in diffusion flames the overall temperatures decrease with increasing pressure. It is shown that the rate of temperature drop is greater for a pressure increase at lower pressures in comparison with higher pressures.