Dissertations / Theses on the topic 'Borage'

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A impregnação de polímeros com princípios ativos de fármacos usando o dióxido de carbono a alta pressão constitui-se em uma das formas de processamento de polímeros para obtenção de sistemas de liberação controlada. A modelagem e a simulação do processo de impregnação são especialmente importantes para a previsão da viabilidade técnica do processo e a escolha das melhores condições operacionais com redução dos esforços experimentais. Nesse sentido, a presente dissertação tem como objetivo modelar e simular a impregnação de membranas de poliuretano com óleo de borage usando CO2 denso para aplicação no tratamento de feridas dérmicas. Para tanto, é crucial a descrição adequada do comportamento termodinâmico do sistema ternário CO2-óleo de borage-poliuretano a alta pressão, que não é uma tarefa trivial, pois necessita de dados de equilíbrio de fases dos sistemas binários correspondentes ainda pouco estudados na literatura. A modelagem e a simulação do processo de dessorção de CO2 em poliuretano foram realizadas utilizando-se as soluções analítica e numérica da 2ª. lei de Fick para descrição do fenômeno de transferência de massa. A determinação da quantidade máxima de CO2 sorvida no poliuretano foi obtida pela extrapolação da curva de dessorção até o tempo zero para diferentes condições de temperatura, pressão e tempo de sorção. O emprego das soluções analítica e numérica da 2ª. lei de Fick geraram resultados semelhantes tanto para o coeficiente de difusão quanto para a quantidade de CO2 sorvida pelo poliuretano. A predição do comportamento termodinâmico do óleo de borage em CO2 denso foi feita a partir da correlação de dados de solubilidade usando a equação de estado de Peng-Robinson com dois tipos de regra de mistura: a clássica e a LCVM. Devido à complexidade do sistema e a ausência de dados experimentais, as propriedades físico-químicas do óleo de borage foram estimadas por métodos de contribuição de grupos. Os resultados da correlação da solubilidade do óleo de borage em CO2 indicaram que o tipo de regra de mistura não é o fator determinante vi para o bom ajuste do modelo aos pontos experimentais, mas sim a quantidade de parâmetros ajustáveis utilizados. Observou-se que apenas a regra de mistura clássica com dois parâmetros ajustáveis dependentes da temperatura é capaz de descrever satisfatoriamente o comportamento termodinâmico desse sistema. A modelagem do equilíbrio de fases do sistema ternário foi feita através da predição do coeficiente de partição do óleo de borage entre as fases polimérica e fluida, a partir dos dados experimentais dos sistemas binários, usando-se a teoria do equilíbrio de fases e modelos específicos. Observou-se que, apesar da escassez de dados de equilíbrio de fases para os sistemas binários, é possível fazer uma avaliação qualitativa satisfatória a partir do cálculo preditivo do coeficiente de partição do óleo de borage. Os resultados mostraram que a ordem de grandeza do coeficiente de partição calculado é a mesma dos valores obtidos a partir dos dados experimentais de impregnação.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior
This study aimed to obtain semisolids formulations and lipid core nanocapsules containing borage oil associated or not with betamethasone dipropionate, for their application in the treatment of atopic dermatitis. A gel-cream containing borage oil was prepared and presented satisfactory results for performed tests (pH, spreadability and viscosity suitable for topical application). The in vivo assay showed topical anti-inflammatory action of the oil in rats. Additionally, nanocapsule suspensions containing borage oil and betamethasone dipropionate were prepared by interfacial deposition of preformed polymer method and were characterized. The colloidal suspensions, showed a slightly acid pH (6.0-6.2), nanosized particles (180-210 nm), with a low polydispersity index (<0.1), negative zeta potential (-9 to -16 mV), betamethasone content was close to theoretical and encapsulation efficiency of approximately 100%. After 15 days of storage at room temperature, only zeta potential. Photodegradation study of of betamethasone dipropionate using UVC light was performed. It was observed a protection against photodegradation conferred by the nanostructured drug delivery systems. The in vitro release study of betamethasone dipropionate from nanocapsule suspensions demonstrated the ability of nanostructures to decrease the drug release. These nanostructures were incorporated into hydrogels (Carbopol® Ultrez and Cellosize®). The hydrogels were evaluated and showed acidic pH, nanosized particle, betamethasone content near to theoretical (0.5 mg / g) and pseudoplastic behavior (Herschel-Bulkley model). In vitro release study of betamethasone dipropionate from the hydrogels demonstrated a reduced release of the drug in the different analysis times, as compared with hydrogels containing the non-associated drug. The in vivo anti-inflammatory assay showed the anti-inflammatory activity of the hydrogels containing the nanostructures, which can demonstrate the drug and the oil activity when combined with polymeric nanocapsules.
Esse trabalho buscou obter formulações semissólidas e nanocápsulas de núcleo lipídico contendo o óleo de borragem associado ou não ao dipropionato de betametasona, visando sua aplicação no tratamento da dermatite atópica. Uma formulação semissólida do tipo creme-gel contendo o óleo de borragem foi preparada e apresentou resultados satisfatórios para os testes empregados (pH, espalhabilidade e viscosidade adequadas para aplicação tópica). O ensaio in vivo realizado em ratos Wistar evidenciou a ação anti-inflamatória tópica do óleo. Adicionalmente, suspensões de nanocápsulas foram preparadas pelo método de deposição interfacial de polímero pré-formado, contendo o óleo de borragem e dipropionato de betametasona, as quais foram caracterizadas em relação ao tamanho médio de partículas, índice de polidispersão (PdI), potencial zeta, microscopia de transmissão eletrônica, pH, teor de fármaco e eficiência de encapsulamento. As formulações apresentaram pH levemente ácido (6,0-6,2), partículas de tamanho nanométrico (180-210 nm), baixo índice de polidispersão (< 0,1), potencial zeta negativo (-9 a -16 mV), teor de betametasona próximo ao teórico e eficiência de encapsulamento de, aproximadamente, 100%. No período de 15 dias de armazenamento, a temperatura ambiente, apenas o potencial zeta. O estudo de fotodegradação do dipropionato de betametasona frente à luz UVC foi realizado e evidenciou a relevância dos sistemas nanoestruturados na proteção do fármaco. O estudo de liberação in vitro a partir das suspensões demonstrou a capacidade das nanocápsulas em reduzir a liberação do fármaco. As nanoestruturas foram incorporadas em hidrogéis (Carbopol® Ultrez e Cellosize®), os quais foram avaliados quanto ao pH, tamanho de partículas, espalhabilidade, propriedades reológicas e teor de fármaco. Os hidrogéis apresentaram pH ácido, tamanho de partícula nanométrico, teor de betametasona próximo ao teórico (0,5 mg/g) e comportamento pseudoplástico (modelo Herschel-Bulkley). No estudo de liberação in vitro do dipropionato de betametasona a partir dos hidrogéis verificou-se uma liberação menor do fármaco nos diferentes tempos de análise em comparação com os hidrogéis contendo o fármaco não associado. O ensaio in vivo para avaliar a atividade anti-inflamatória dos hidrogéis contendo as nanoestruturas foi também realizado, sendo possível comprovar a atividade do fármaco e do óleo quando associados à nanocápsulas poliméricas.

Die eingereichte Dissertation mit dem Thema „Heterogen katalysierte Hydrodehalogenierung von Borhalogeniden im Rahmen eines in sich geschlossenen BNHx-Recyclingkonzepts“ beinhaltet drei für das BNHx-Recycling zentrale Reaktionsschritte: Supersäureaufschluss, Hydrodehalogenierung und den Basenaustausch. Mit Hilfe dieser drei Schritte ist es möglich, die Zersetzungsrückstände von BH3NH3(Polyaminoboran, Borazin und Polyborazylen) wieder in BH3NH3 zu überführen, ohne teure Reduktionsmittel wie LiAlH4 oder Hydrazin verwenden zu müssen. Das Verfahren ermöglichte in einem Durchlauf die Gewinnung von 60 % der eingesetzten Menge an BH3NH3 ohne eine Erzeugung von Abfallprodukten. Mit Hilfe der Chloralkalielelektrolyse kann das Verfahren an Wind- bzw. Solarkraftwerke gekoppelt und über diese alle benötigten Ausgangsstoffe hergestellt werden. Die katalytische Erzeugung von B-H-Spezies auf der Grundlage der Aktivierung von molekularem Wasserstoff ist als Schwerpunkt dieser Arbeit zu sehen. Die mechanistischen Studien lieferten ein genaueres Verständnis über fundamentale Zusammenhänge zwischen dem Lösungsmittel Et3N und der Wasserstoffbereitstellung über die N-CH2-Gruppierung sowie der Wirkungsweise des Katalysators.

Trichogramma carverae Oatman and Pinto is mass-released for biological control of the leafroller pest, light brown apple moth, Epiphyas postvittana (Walker) in Australian vineyards. Parasitoid performance can, however, be constrained by a lack of suitable adult food and no information is available on the effect of nectar on the parasitism and longevity of T. carverae. To address this, the effect of alyssum, Lobularia maritima (L.) flowers on E. postvittana parasitism was studied in a vineyard experiment with and without releases of T. carverae. Egg parasitoid activity was assessed with E. postvittana egg 'sentinel cards' and no parasitism was recorded in plots without T. carverae releases. Where T. carverae were released, there was no significant enhancement of parasitism by the presence of L. maritima flowers. Three hypotheses were subsequently tested to account for the lack of an effect: (i) T. carverae does not benefit from L. maritima nectar, (ii) T. carverae was feeding on nectar from other flowering plants (weeds) present in the vineyard, (iii) T. carverae was feeding on sugars from ripe grapes. A growth-cabinet experiment using potted L. maritima plants with and without flowers did not support hypothesis one. No parasitism was recorded after day two for T. carverae caged without flowers whilst parasitism occured until day eight in the presence of flowers. A laboratory experiment with common vineyard weeds (Trifolium repens, Hypochoeris radicata, Echium plantagineum) as well as L. maritima did not support hypothesis one but gave partial support to hypothesis two. Survival of T. carverae was enhanced to a small but statistically significant extent in vials with intact flowers of L. maritima, white clover (T. repens) and catsear (H. radicata) but not in vials with flowering shoots of these species from which flowers and flowering buds had been removed. Paterson's curse (E. plantagineum) flowers had no effect on T. carverae survival. In a laboratory study, punctured grapes significantly enhanced T. carverae survival compared with a treatment without grapes, supporting hypothesis three. Trichogramma carverae performance in the field experiment was probably also constrained by relatively cool and wet weather. Further work on the enhancement of T. carverae efficacy by L. maritima and other carbohydrate sources is warranted. Greenhouse and field experiments were conducted to investigate whether T. carverae benefit from different groundcover plant species. Ten T. carverae adults (<24h after eclosion) were caged with different groundcover species and a control with no plant materials. Epiphyas postvittana egg sentinel cards were used to measure parasitism and longevity was recorded visually. Survival and realised parasitism of T. carverae was significantly higher in L. maritima than in Brassica juncea, Coriandrum sativum, shoots of these species from which flowers had been removed and nil control treatments. A similar experiment with Fagopyrum esculentum (with- and without-flowers) and a control treatment showed that survival was significantly higher in intact F. esculentum than in without-flower and control treatments. There was no significant treatment effect on parasitism in the early stages of that experiment, though parasitism was recorded in the presence of F. esculentum flowers for 12 days, compared with 6 days in other treatments. Higher parasitism was observed in intact Borago officinalis than in the flowerless shoot, water only and no plant material control treatments in a third experiment. There was no significant treatment effect on parasitism. Fitted exponential curves for survival data differed significantly in curvature in the first, second and third experiments but the slope was a non-significant parameter in the second and third experiments. In a second series of laboratory experiments, one male and one female T. carverae were caged with groundcover species to investigate male and female longevity and daily fecundity. Both male and female longevity in F. esculentum and L. maritima treatments were significantly higher than on shoots of these species from which flowers had been removed, and than in the control treatments. Daily fecundity was significantly greater in the intact L. maritima treatment than in all other treatments. Fitted exponential curves for daily fecundity differed significantly in position and slope but not in curvature. There was no significant treatment effect on longevity or parasitism when a male and female were caged with intact B. juncea, B. officinalis or without-flower of these species, nor in the treatment with no plant materials. No parasitism was observed in a survey of naturally occurring egg parasitoids on two sites close to Orange and Canowindra in New South Wales, illustrating the importance of mass releases of T. carverae in biological control of E. postvittana. In an experiment on the Canowindra site, parasitism was significantly higher on day one and day two after T. carverae release when with-flower treatments were compared with without-flower treatments. Parasitism was significantly higher in the F. esculentum treatment than in C. sativum, L. maritima, vegetation without-flowers and control treatments on these dates. On day five, parasitism was higher in C. sativum than in all other treatments. There was no significant increase in parasitism in a second experiment conducted on the Orange site. Coriandrum sativum, F. esculentum and L. maritima appear to be suitable adult food sources for T. carverae and offer some scope for habitat manipulation in vineyards The adults of many parasitoid species require nectar for optimal fitness but very little is known about flower recognition. Flight cage experiments showed that the adults of T. carverae benefited from L. maritima bearing white flowers to a greater extent than was the case for light pink, dark pink or purple flowered cultivars, despite all cultivars producing nectar. Survival and realised parasitism on non-white flowers were no greater than when the parasitoids were caged on L. maritima shoots from which flowers had been removed. The possibility that differences between L. maritima cultivars were due to factors other than flower colour, such as nectar quality, was excluded by dyeing white L. maritima flowers by placing the roots of the plants in 5% food dye (blue or pink) solution. Survival of T. carverae was lower on dyed L. maritima flowers than on undyed white flowers. Mixing the same dyes with honey in a third experiment conducted in the dark showed that the low level of feeding on dyed flowers was unlikely to be the result of olfactory or gustatory cues. Flower colour appears, therefore, to be a critical factor in the choice of plants used to enhance biological control, and is likely to also be a factor in the role parasitoids play in structuring invertebrate communities. Provision of nectar producing plants to increase the effectiveness of biological control is one aspect of habitat manipulation, but care needs to be taken to avoid the use of plant species that may benefit pest species. Greenhouse experiments were conducted to investigate whether the adult E. postvittana and larvae benefit from nectar producing groundcover species. Newly emerged E. postvittana adults were caged with different groundcover species and a honey-based artificial adult diet. The longevity of male and female E. postvittana when caged with shoots of borage (B. officinalis) and buckwheat (F. esculentum) bearing flowers was as long as when fed a honey-based artificial diet. This effect was not evident when caged with shoots of these plants from which flowers had been removed. Longevity was significantly lower than in the artificial diet treatment when caged with coriander (C. sativum) or alyssum (L. maritima) irrespective of whether flowers were present or not. There was no significant treatment effect on the lifetime fecundity of E. postvittana. A second experiment with mustard (B. juncea) (with- and without-flowers), water only and honey-based artificial adult diet showed no significant treatment effects on the longevity of male and female E. postvittana or on the lifetime fecundity of E. postvittana. The anomalous lack of a difference between the water and honey-based diet treatments precludes making conclusions on the value of B. juncea for E. postvittana. Two greenhouse experiments were conducted to evaluate the effects of groundcover species on the larval development of E. postvittana. In the first experiment, larval mortality was significantly higher in C. sativum, and L. maritima than in B. juncea, B. officinalis and white clover (T. repens) a known host of E. postvittana. Coriandrum sativum and L. maritima extended the larval period. In B. juncea and B. officinalis, mortality did not differ from that in T. repens. In F. esculentum, larval mortality was significantly higher than in T. repens. A short larval period was observed on B. juncea, B. officinalis and F. esculentum. Fitted exponential curves for larval mortality differed significantly in curvature between plant treatments. Similarly, successful pupation was significantly lower in C. sativum, F. esculentum and L. maritima than in T. repens. The percentage of successful pupation in B. juncea and B. officinalis did not differ from F. esculentum and T. repens. Fitted exponential curves for pupation differed significantly in curvature. A similar trend was observed in a second experiment with potted plants. The overall results suggest that C. sativum and L. maritima denied benefit to E. postvittana adults and larvae, so could be planted as vineyard groundcover with minimal risk of exacerbating this pest. Overall results suggest that T. carverae require nutrients to reach their full reproductive potential and flowers provide such nutrients. Lobularia maritima and C. sativum may be considered 'selective food plants' for T. carverae whereas F. esculentum appears to be a 'non-selective food plant'; both T. carverae and E. postvittana benefited from it. Fruits such as grapes can be used as food resources in habitat manipulation and this merits further research. This result also suggests that within species flower colour is an important factor for flower selection in habitat manipulation.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
O presente trabalho visou estudar a viabilidade de incorporação de agentes bioativos em curativos poliméricos utilizando dióxido de carbono supercrítico (CO2). Foram utilizados dois curativos comerciais: Foam Dressing (poliuretano) e Promogran® (colágeno e celulose regenerada oxidada). Como bioativos, foram testados o óleo de borage e o extrato de jambu. Foram realizados ensaios de sorção de CO2 supercrítico nessas matrizes poliméricas sob diferentes condições, de modo a potencializar a incorporação de agentes bioativos. Isto pode ser útil para futuros trabalhos na área de impregnação/deposição de agentes bioativos em curativos de espuma, já que é o primeiro estudo com estes tipos de material (curativos e bioativos) nestas condições experimentais. Os resultados mostraram que a melhor condição de sorção para ambos os polímeros foi obtida na temperatura de 308,15 K e densidade do CO2 igual a 850 kg.m-3. O melhor rendimento de impregnação para o óleo de borage em poliuretano (11,8 % m/m) ocorreu nessa mesma densidade do CO2 e na temperatura de 328,15 K. Para o extrato de jambu, o maior rendimento de incorporação na matriz de colágeno e celulose ocorreu nas condições de melhor sorção e com adição de etanol como cossolvente (6,4% m/m). Os resultados obtidos mostraram que a etapa controladora do processo de impregnação/deposição (SSI/SSD) é o equilíbrio de fases e apontam para a possível viabilidade técnica da impregnação de bioativos de origem natural em curativos poliméricos.
ABSTRACT The present work aimed to study the feasibility of incorporation of bioactive agents into polymeric dressings using supercritical carbon dioxide (CO2). Two commercial dressings were investigated: Foam Dressing (polyurethane) and Promogran (collagen and oxidized regenerated cellulose). The bioactives investigated were borage oil and jambu extract. Assays of supercritical CO2 sorption into these polymeric dressings were carried out under different conditions in order to enhance the incorporation of these bioactive agents into the polymer matrices. This can be useful for future works on impregnation/deposition area of bioactive agents in foam dressings, since the study is the first one using these materials (dressings and bioactives) at these experimental conditions. The results showed that the best sorption condition for both polymers was obtained at 308 K and CO2 density equal to 850 kg.m-3. The best impregnation/deposition yield for borage oil and polyurethane (11.8 % w/w) occurred also at this same CO2 density and temperature at 328,15 K. In the case of jambu extract, the highest incorporation yield into the collagen and cellulose matrix occurred under the conditions of highest sorption with the addition of ethanol as a cosolvent (6,4 % w/w). The results showed that SSI/SSD is controlled by phase equilibrium phenomenon and point towards the technical feasibility of this process.

Trichogramma carverae Oatman and Pinto is mass-released for biological control of the leafroller pest, light brown apple moth, Epiphyas postvittana (Walker) in Australian vineyards. Parasitoid performance can, however, be constrained by a lack of suitable adult food and no information is available on the effect of nectar on the parasitism and longevity of T. carverae. To address this, the effect of alyssum, Lobularia maritima (L.) flowers on E. postvittana parasitism was studied in a vineyard experiment with and without releases of T. carverae. Egg parasitoid activity was assessed with E. postvittana egg �sentinel cards� and no parasitism was recorded in plots without T. carverae releases. Where T. carverae were released, there was no significant enhancement of parasitism by the presence of L. maritima flowers. Three hypotheses were subsequently tested to account for the lack of an effect: (i) T. carverae does not benefit from L. maritima nectar, (ii) T. carverae was feeding on nectar from other flowering plants (weeds) present in the vineyard, (iii) T. carverae was feeding on sugars from ripe grapes. A growth-cabinet experiment using potted L. maritima plants with and without flowers did not support hypothesis one. No parasitism was recorded after day two for T. carverae caged without flowers whilst parasitism occured until day eight in the presence of flowers. A laboratory experiment with common vineyard weeds (Trifolium repens, Hypochoeris radicata, Echium plantagineum) as well as L. maritima did not support hypothesis one but gave partial support to hypothesis two. Survival of T. carverae was enhanced to a small but statistically significant extent in vials with intact flowers of L. maritima, white clover (T. repens) and catsear (H. radicata) but not in vials with flowering shoots of these species from which flowers and flowering buds had been removed. Paterson�s curse (E. plantagineum) flowers had no effect on T. carverae survival. In a laboratory study, punctured grapes significantly enhanced T. carverae survival compared with a treatment without grapes, supporting hypothesis three. Trichogramma carverae performance in the field experiment was probably also constrained by relatively cool and wet weather. Further work on the enhancement of T. carverae efficacy by L. maritima and other carbohydrate sources is warranted. Greenhouse and field experiments were conducted to investigate whether T. carverae benefit from different groundcover plant species. Ten T. carverae adults (<24h after eclosion) were caged with different groundcover species and a control with no plant materials. Epiphyas postvittana egg sentinel cards were used to measure parasitism and longevity was recorded visually. Survival and realised parasitism of T. carverae was significantly higher in L. maritima than in Brassica juncea, Coriandrum sativum, shoots of these species from which flowers had been removed and nil control treatments. A similar experiment with Fagopyrum esculentum (with- and without-flowers) and a control treatment showed that survival was significantly higher in intact F. esculentum than in without-flower and control treatments. There was no significant treatment effect on parasitism in the early stages of that experiment, though parasitism was recorded in the presence of F. esculentum flowers for 12 days, compared with 6 days in other treatments. Higher parasitism was observed in intact Borago officinalis than in the flowerless shoot, water only and no plant material control treatments in a third experiment. There was no significant treatment effect on parasitism. Fitted exponential curves for survival data differed significantly in curvature in the first, second and third experiments but the slope was a non-significant parameter in the second and third experiments. In a second series of laboratory experiments, one male and one female T. carverae were caged with groundcover species to investigate male and female longevity and daily fecundity. Both male and female longevity in F. esculentum and L. maritima treatments were significantly higher than on shoots of these species from which flowers had been removed, and than in the control treatments. Daily fecundity was significantly greater in the intact L. maritima treatment than in all other treatments. Fitted exponential curves for daily fecundity differed significantly in position and slope but not in curvature. There was no significant treatment effect on longevity or parasitism when a male and female were caged with intact B. juncea, B. officinalis or without-flower of these species, nor in the treatment with no plant materials. No parasitism was observed in a survey of naturally occurring egg parasitoids on two sites close to Orange and Canowindra in New South Wales, illustrating the importance of mass releases of T. carverae in biological control of E. postvittana. In an experiment on the Canowindra site, parasitism was significantly higher on day one and day two after T. carverae release when with-flower treatments were compared with without-flower treatments. Parasitism was significantly higher in the F. esculentum treatment than in C. sativum, L. maritima, vegetation without-flowers and control treatments on these dates. On day five, parasitism was higher in C. sativum than in all other treatments. There was no significant increase in parasitism in a second experiment conducted on the Orange site. Coriandrum sativum, F. esculentum and L. maritima appear to be suitable adult food sources for T. carverae and offer some scope for habitat manipulation in vineyards The adults of many parasitoid species require nectar for optimal fitness but very little is known about flower recognition. Flight cage experiments showed that the adults of T. carverae benefited from L. maritima bearing white flowers to a greater extent than was the case for light pink, dark pink or purple flowered cultivars, despite all cultivars producing nectar. Survival and realised parasitism on non-white flowers were no greater than when the parasitoids were caged on L. maritima shoots from which flowers had been removed. The possibility that differences between L. maritima cultivars were due to factors other than flower colour, such as nectar quality, was excluded by dyeing white L. maritima flowers by placing the roots of the plants in 5% food dye (blue or pink) solution. Survival of T. carverae was lower on dyed L. maritima flowers than on undyed white flowers. Mixing the same dyes with honey in a third experiment conducted in the dark showed that the low level of feeding on dyed flowers was unlikely to be the result of olfactory or gustatory cues. Flower colour appears, therefore, to be a critical factor in the choice of plants used to enhance biological control, and is likely to also be a factor in the role parasitoids play in structuring invertebrate communities. Provision of nectar producing plants to increase the effectiveness of biological control is one aspect of habitat manipulation, but care needs to be taken to avoid the use of plant species that may benefit pest species. Greenhouse experiments were conducted to investigate whether the adult E. postvittana and larvae benefit from nectar producing groundcover species. Newly emerged E. postvittana adults were caged with different groundcover species and a honey-based artificial adult diet. The longevity of male and female E. postvittana when caged with shoots of borage (B. officinalis) and buckwheat (F. esculentum) bearing flowers was as long as when fed a honey-based artificial diet. This effect was not evident when caged with shoots of these plants from which flowers had been removed. Longevity was significantly lower than in the artificial diet treatment when caged with coriander (C. sativum) or alyssum (L. maritima) irrespective of whether flowers were present or not. There was no significant treatment effect on the lifetime fecundity of E. postvittana. A second experiment with mustard (B. juncea) (with- and without-flowers), water only and honey-based artificial adult diet showed no significant treatment effects on the longevity of male and female E. postvittana or on the lifetime fecundity of E. postvittana. The anomalous lack of a difference between the water and honey-based diet treatments precludes making conclusions on the value of B. juncea for E. postvittana. Two greenhouse experiments were conducted to evaluate the effects of groundcover species on the larval development of E. postvittana. In the first experiment, larval mortality was significantly higher in C. sativum, and L. maritima than in B. juncea, B. officinalis and white clover (T. repens) a known host of E. postvittana. Coriandrum sativum and L. maritima extended the larval period. In B. juncea and B. officinalis, mortality did not differ from that in T. repens. In F. esculentum, larval mortality was significantly higher than in T. repens. A short larval period was observed on B. juncea, B. officinalis and F. esculentum. Fitted exponential curves for larval mortality differed significantly in curvature between plant treatments. Similarly, successful pupation was significantly lower in C. sativum, F. esculentum and L. maritima than in T. repens. The percentage of successful pupation in B. juncea and B. officinalis did not differ from F. esculentum and T. repens. Fitted exponential curves for pupation differed significantly in curvature. A similar trend was observed in a second experiment with potted plants. The overall results suggest that C. sativum and L. maritima denied benefit to E. postvittana adults and larvae, so could be planted as vineyard groundcover with minimal risk of exacerbating this pest. Overall results suggest that T. carverae require nutrients to reach their full reproductive potential and flowers provide such nutrients. Lobularia maritima and C. sativum may be considered �selective food plants� for T. carverae whereas F. esculentum appears to be a �non-selective food plant�; both T. carverae and E. postvittana benefited from it. Fruits such as grapes can be used as food resources in habitat manipulation and this merits further research. This result also suggests that within species flower colour is an important factor for flower selection in habitat manipulation.

The path of research in the pulp and paper industry is heading towards the elimination of the lime cycle, which requires large amounts of energy, and changing the conventional recovery boiler system to a gasification process that will reduce the possibility of smelt water explosions while meeting future environmental regulations. Research has been carried out on both gasification processes and on causticizing processes that can replace or complement the lime cycle, however very little research has gone into the actual kinetics of causticization using black liquor in gasification processes. This research project fills in some of the missing knowledge in the area of kinetics of autocausticization reactions, which entails the use of borates as the autocausticizing agent. A temperature dependent kinetic model coupled with a mass transfer coefficient has been developed and compared to experimental data.

Embora cristais boratos dopados com ions de terras raras sejam amplamente investigados, vidros boratos desses sistemas vêm sendo pouco estudados. O cristal NdAl3(BO3)4(NAB) cujas propriedades laser e de geração de segundo harmônico (GSH) são conhecidas e continuamente relatadas na literatura, vem sendo recentemente considerado como um forte candidato para dispositivo \"microchip laser\". Alem disso, cristais dopados com íons de neodímio têm demonstrado ser excelentes para o bombeio com laseres de diodo, devido ao intenso pico de absorção próximo a 800 nm. Entretanto, existe na literatura um número muito limitado de estudos relatando as propriedades de vidros do sistema Nd2O3-Al2-O3-B2O3. Partindo dessa premissa, o objetivo principal deste trabalho foi obter vidros neste sistema, para elevadas concentrações de Nd2O3 (5-20 mol%), por meio das técnicas de fusão/moldagem convencional e fusão a laser. Dentre os materiais preparados foram obtidos três vidros transparentes, um material com separação de fases e, onde ocorreu cristalização. Os vidros obtidos, NAB136, NAB152560 e NAB226 foram caracterizados através das técnicas de análise térmica diferencial (ATD), difratometria de raios X (DRX), absorção óptica (AO) e ICP-OES (análise de composição). De acordo como os resultados de ATD, os vidros não apresentaram uma variação significativa na temperatura de transição vítrea (Tg) com o aumento da concentração de Nd2O3. O vidro NAB136, obtido com composição próxima a do cristal NdAl3(BO3)4(NAB), foi submetido a um tratamento térmico de cristalização a uma temperatura de 820°C por 2 horas. Os resultados de DRY indicaram a presença das fases cristalinas majoritárias Al4B2O9 e NAB. Medidas de absorção Óptica (AO) dos vidros no intervalo espectral de 300-1000 nm indicaram intensa absorção nos comprimentos de onda 500 nm e 800 nm. As análises de ICP-OES indicaram alta pureza dos vidros e composições próximas das composições nominais
Although borate crystals doped with rare earth ions have already been extensively investigated, borate glasses of these systems were not widely studied. The NdAl3(BO3)4(NAB) crystal, which laser and second harmonic generation (SGH) properties are well know and continuously mentioned in literature, has been recently considered as a strong candidate for microchip laser devices. Moreover, neodymium doped crystals are known for their excellent performance when pumped with diode lasers due to its intense absorption peak near to 800 nm. However, a limited number of papers have been published referring to the properties of glasses in the system Nd2O3-Al2-O3-B2O3. Based on this premise, the main purpose of this work was to prepare glasses in this system for Nd2O3 elevate concentrations (5-20 mol%) by the conventional melting/molding and laser heated methods. Among the prepared materials it was obtained three clear glasses, a material with phase separation and another one, which has crystallized. The obtained glasses, NAB136, NAB152560 and NAB226, where characterized by differential thermal analysis (DTA), X-ray diffractometry (XRD), optical absorption (OA) and ICP-OES (compositional analysis). According to the DTA results, the glasses have not presenteá a rneaningfut change in the glass transition temperature (Tg) with the increase of Nd2O3 content. The NAB136 glass, with the closest composition to the crystal NdAl3(BO3)4(NAB), was submitted to a crystallization thermal treatment at 820°C for 2 hours. XRD results showed the existence of the main crystalline phases and NAB. Optical absorption (OA) measurements of the glasses in the spectral range 300-1000 nm indicated intense absorpâion in the 500 nm and 800 nm wavelengths. ICP-OES analysis showed that the glasses posses high purity stoichiometry, close to the nominal ones

Ao longo dos últimos anos tem aumentado o interesse da comunidade científica no desenvolvimento de estruturas de borato de magnésio. Geralmente, o borato de magnésio é utilizado em conjunto com outros materiais como metais, polímeros, cerâmicas ou macromoléculas formando compósitos. Este borato tem sido largamente utilizado para reduzir o coeficiente de fricção e aprimorar as propriedades mecânicas de compósitos, atuando como material anti-desgaste e inibidos de corrosão. Dentre as fases de borato de magnésio, o Mg2B2O5 se destaca por apresentar potencial para aplicações tais como catalisador para conversão de hidrocarbonetos, agente para tratamento eletrocondutivo, semicondutor e material luminescente para aplicação em tubos de raios catódicos. Acredita-se que ao reduzir as dimensões do bulk de borato de magnésio a dimensões nanométricas, pode-se oferecer excelentes características para desenvolver e melhorar as potenciais aplicações acima mencionadas. Em geral, estruturas em nanoescala como tubos, fios, rods, cintos e whiskers têm sido o foco de intensiva pesquisa. Buscando a compreensão dos mecanismos para produção de nanoestruturas de boratos de magnésio, este trabalho está focado no desenvolvimento de uma rota de síntese de nanorods de Mg2B2O5 que permita a produção de um material com elevada pureza e homegeneidade estrutural a fim de possibilitar uma futura aplicação em dispositivos nanotecnológicos. Os nanorods foram sintetizados utilizando como precursor B2O3 e Mg metálico em um reator de CVD. Foi analisado o emprego de diferentes atmosferas para a reação, partindo de H2, Ar e acetonitrila (CH3CN). Foi estudado também a influência da temperatura na morfologia e composição dos nanorods. As propriedades físico-químicas das estruturas desenvolvidas foram caracterizadas por FTIR e DRX. A estrutura morfológica foi analisada por MEV e MET e as propriedades óticas por DRS. De acordo com os resultados, os nanorods foram obtidos com alto grau de pureza e homogeneidade morfológica utilizando uma atmosfera redutora composta por H2 e CH3CN.
Over the last few years the interest of the scientific community has increased in the development of magnesium borate structures. Borato has been widely used to reduce the coefficient of friction and improve the mechanical properties of composite materials such as anti-wear and corrosion. Generally, the magnesium borate is used together with other materials such as metals, polymers, ceramics and macromolecules to form compounds. Among the borate magnesium phases, Mg2B2O5 contrasts for presenting potential for applications such as acting as a catalyst for hydrocarbon conversion, as an agent for electroconductive treatment, as a semiconductor and luminescent material for application in cathode ray tubes. It is believed that by reducing the borate magnesium bulk dimensions to dimensions of nanostructures, it can provide excellent characteristics to develop and improve the potential applications mentioned above. In general, nanoscale structures such as tubes, wires, rods, belts and whiskers have been the focus of intensive research. Seeking to understand the mechanisms for production of magnesium borate nanostructures, this work is focused on the development of a synthesis method for Mg2B2O5 nanorods, enabling the production of a material with high purity and structural homogeneity to enable future application in nanotechnological devices. The physicochemical properties of the structures developed were characterized by FTIR and XRD. The morphological structure was examined by SEM and TEM and the optical properties by DRS. According to the results, high purity and morphological uniform nanorods were obtained using a H2 and CH3CN reducing atmosphere.

Les borates, matériaux optiques non linéaires (ONL), sont d’excellents candidats pour obtenir de l’émission dans le bleu et l’ultra-violet (UV) par conversion de fréquence dans des guides d’ondes. Au sein de la famille des borates, notre intérêt s’est porté sur le métaborate de baryum (BBO) puisqu’il fait partie des matériaux ONL qui possèdent une gamme de transparence étendue dans l’UV, des coefficients non linéaires suffisamment élevés et un seuil de dommage optique important. L’objectif de ce mémoire est de montrer la faisabilité de la croissance de films de BBO par une technique MOCVD à injection. Son principe repose sur l’introduction de micro-quantités d’une solution, contenant les précurseurs organométalliques dissous dans un solvant, dans un évaporateur où a lieu une évaporation flash. Les couches minces ont été caractérisées par diverses méthodes (microscopie optique, analyses micro-Raman, XPS, FTIR) dans la gamme de composition molaire en solution allant de riche en bore (Ba :B=1 :56) à stoechiométrique (Ba :B=1 :2) et pour diverses températures de croissance. Pour un rapport molaire Ba :B=1 :2 et une température de croissance proche de 700 ◦C, des analyses XPS corroborées par des analyses micro-Raman, ont permis de mettre en évidence la présence de la phase BBO dans les couches minces
Thin films of nonlinear optical (NLO) material provide excellent prospects for integrated optical applications requiring UV waveguides. Among the family of NLO borate compounds, barium metaborate (BBO) is particularly attractive because it has a variety of favourable properties such as a wide optical transmis- sion range, rather large nonlinear optical coefficients and a high damage thre- shold. The main objective of the present work was the growth and characterization of BBO thin films by injection metal organic chemical vapour deposition (injection-MOCVD). This method is based on the computer-controlled injection of micro amounts of a solution into an evaporator system. There, the solution containing precursors dissolved in an appropriate solvent is flash vaporised. Thin films were deposited with a molar composition from boron rich (Ba :B=1 :56) to stoichiometric (Ba :B=1 :2) and different growth temperatures and characte- rised by several methods (optical microscopy, micro-Raman spectroscopy, XPS, FTIR). The best BBO layers were obtained for Ba :B=1 :2 molar ratio and for a growth temperature of around 700 ◦C. The successful growth of BBO was confirmed by micro-Raman and XPS analysis

Lewis base borane adducts (LB·BH3) constitute a well-known class of molecules with a number of diverse applications, including use as protected phosphines. The kinetics and thermodynamics of borane transfer reactions from a wide range of Lewis base borane complexes have been studied. The data generated has been used both as a quantitative tool to describe the nucleofugality (leaving group ability) of Lewis bases and as a means to improve the efficiency of phosphine borane deprotection reactions. The kinetics of borane transfer from a range of tertiary phosphine borane complexes to a wide range of amines have been determined. All kinetic data obtained, in addition to computational evidence, are consistent with a direct (SN2-like) mechanism, rather than a dissociative (SN1-like) process. The identities of the amine, phosphine and to a lesser extent solvent, impact substantially on the rate and equilibrium of the transfer, which can span several orders of magnitude. In depth structure activity relationships have been explored both for a wide variety of amine nucleophiles and phosphine nucleofuges. Taken as a whole, the data allow informed optimisation of the “deprotection” of a phosphine borane complex from the standpoint of rate or synthetic convenience. Additionally, the kinetics of ethanolysis of tri(o-tolyl)phosphine borane complex have also been studied. Using bridgehead amine quinuclidine as a benchmark, the kinetics of borane transfer from a wide range amine borane adducts have also been determined. Parameterisation of these data, in addition to that obtained for the analogous phosphine borane complexes, has allowed development of a novel nucleofugality scale (NFB) that quantifies the leaving group ability of a wide range of Lewis bases. Additivity in the kinetics across a series R3−nR’nX·BH3 (X = P, N; R/R’ = aryl, alkyl) has led to the formulation of related substituent parameters (nf PB, nfAB) that quantify the nucleofugal influence of a substituent. Using the substituent nucleofugality parameter in concert with additivity provides a mean of calculating ligand nucleofugality (NFB) values for a wide range of Lewis bases that extends far beyond those experimentally derived. Good agreement was found between predicted (using NF B and nFB values) and experimental rates of borane transfer for ligands outside the training set, thus providing a means to predict the relative rate of phosphine borane deprotections. The utility of both parameters was demonstrated through correlations to rates of redox transformations at iridium (bearing phosphine spectator ligands) and MIDA boronate hydrolysis, (MIDA = N-methyliminodiacetic acid). Through these correlations, interesting subtleties in the mechanism of MIDA boronate hydrolysis have been identified.

In Siedewasserreaktoren ist ein Boreinspeisesystem diversitär wirkend zur Reaktorschnellabschaltung installiert. Dieses System garantiert, dass der Reaktor beim Versagen des Schnellabschaltesystems in einen unterkritischen Zustand überführt werden kann. Der aufgrund der Nachzerfallsleistung entweichende Dampf trägt jedoch ständig einen Teil des eingespeisten Bors in Form von Borsäure mit sich. Da dieser Prozess bisher nicht quantifiziert wurde, ist somit das Eintreten einer Rekrititkalität während der Transiente ohne weitere Untersuchungen nicht auszuschließen. In der vorliegenden Arbeit erfolgt die Erstellung einer fundierten Datenbasis zur Quantifizierung des Borverlusts an verschiedenen Betriebspunkten. Dazu stehen nach vorheriger Konstruktion und Inbetriebnahme zwei Versuchsanlagen zur Verfügung, ein Versuchsautoklav und der Siedewasserreaktor-Simulator BORAN. Das in diesen Versuchsanlagen enthaltene und als Kühlmedium genutzte entionisierte Wasser wird wie bei einem Siedewasserreaktor mit einer hochkonzentrierten Lösung der Borverbindung Dinatrium-Pentaborat-Dekahydrat versetzt. Für weiterführende Untersuchungen findet auch Borsäure Verwendung. Die Bestimmung des Borgehalts der Kondensate des entwichenen Dampfes erfolgt mit Massenspektrometrie mit induktiv gekoppeltem Plasma (ICP-MS). Die durch Variation von Borkonzentration, Temperatur, pH-Wert und Volumendampfgehalt erzeugten Messdaten fließen in einem Flüchtigkeitsmodell in Form einer empirischen Gleichung zusammen, welches in den Thermohydraulikcode ATHLET implementiert wird. Experimente am SWR-Simulator BORAN und entsprechende Rechnungen mit dem modifizierten Code ATHLET von Langzeit-Deborierungstransienten bei unterschiedlichen Randbedingungen bestätigen das Flüchtigkeitsmodell. Gleichzeitig erfolgt mittels dieser Experimente die Validierung des Modells im ATHLET mit hinreichender Genauigkeit. Mit den Ergebnissen aus Rechnungen und Experimenten wird das Boreinspeisesystem in seiner aktuellen Konfiguration bewertet und mit zukünftigen Konzepten verglichen. Schlussendlich erfolgt der Nachweis, dass die Funktionalität des Boreinspeisesystem aus dem Blickwinkel der durchgeführten Analysen, trotz der nachgewiesenen Borflüchtigkeit, die Forderungen der KTA 3103 erfüllt und aufgrund der nachgewiesenen Borflüchtigkeit binnen der ersten beiden Stunden der Transiente keine Rekritikalität verursacht wird
In boiling water reactors a boron injection system as an alternative system is installed to guarantee that the reactor shut down in case of a total or partial ATWS accident. Because of the heat generated by the fission products after shutting down a part of the injected boron is evaporated as boron acid. This process is not characterized quantitatively yet. This is the reason that the incidence of recriticality during a transient cannot be excluded without further research. In the following studies a funded database quantifying the loss of boron is established. The volatility of the boron solution was measured by experiments in a small autoclave and in a boiling water reactor simulator called BORAN after construction. The deionised water used as coolant in the facilities will be enriched with boron by a high concentrated solution of Disodium-Pentaborate-Decahydrate. The measurement of the boron concentration in the condensates of the exhausted vapour is carried out by inductively-coupled-plasma mass-spectrometry (ICP-MS). For additional analysis boron acid is also used. The boron concentration in the vapour mainly depends on the temperature and void fraction of the two-phase-flow. This volatility model in form of an empiric equation is implemented in the thermo hydraulic ATHLET-code. Furthermore the reason of the volatility of the analysed solutions will be discussed within a chemical and physical background. Experiments at the BORAN facility and corresponding calculation with the modified ATHLET-code of long time deboration transients with different boundary conditions prove the volatility model. Thereby the code will be validated with sufficient accuracy. The modified code with an adapted Input-Dataset provides the possibility to calculate transients with the loss of boron. With the consideration of the volatility the demand of the KTA-rule 3103 on the Boron injection system is also grantable

Cette thèse traite de l'utilisation de molécules dîtes ambiphiles, comportant à la fois un site donneur et accepteur d'électrons, en chimie organométallique, en tant que ligand.

Dans le premier chapitre, une étude bibliographique décrit l'utilisation des acides de Lewis du groupe 13 en tant que co-catalyseur en chimie organométallique, afin de mieux comprendre quel rôle pourrait jouer celui-ci au sein d'un ligand ambiphile coordiné sur un métal de transition. Les différents modes de coordination de ces ligands sont examinés. Les rares contributions traitant de la réactivité de ce type de complexes sont également décrites.

Le second chapitre décrit la synthèse par couplage bore-carbone d'une nouvelle famille de ligands ambiphiles, 2-picolylboranes. En fonction des substituants du bore, ces composés sont obtenus sous forme dimère ou monomère fermé par interactions datives donneur-accepteur, inter ou intramoléculaires. Le comportement en solution du 2-picolylBCy2 a été examiné attentivement. Un équilibre entre la forme dimère et monomère est mis en évidence. Des calculs théoriques valident nos conclusions. La coordination de ce ligand sur plusieurs précurseurs métalliques est étudiée. Un exemple rare de coordination pontante donneur→Ru-Cl→accepteur a été caractérisé dans le complexe [(p-cym)RuCl2(2-picolylBCy2)].

Dans le troisième chapitre, la synthèse par hydroboration d'une famille de ligands ambiphiles, 1,2-phosphinoethylborane, est décrite. Deux complexes de ruthénium neutres contenant ces ligands, ainsi que leur dérivés cationiques sont caractérisés. Des tests catalytiques préliminaires d'hydrosilylation du benzaldéhyde avec l'un des complexes cationiques ont montré la dégradation rapide du pré-catalyseur en un complexe ruthénacycle original. Sa réactivité avec un chloroborane et un chloroalane est étudiée.

Cette thèse traite de l'utilisation de molécules dîtes ambiphiles, comportant à la fois un site donneur et accepteur d'électrons, en chimie organométallique, en tant que ligand. Dans le premier chapitre, une étude bibliographique décrit l'utilisation des acides de Lewis du groupe 13 en tant que co-catalyseur en chimie organométallique, afin de mieux comprendre quel rôle pourrait jouer celui-ci au sein d'un ligand ambiphile coordiné sur un métal de transition. Les différents modes de coordination de ces ligands sont examinés. Les rares contributions traitant de la réactivité de ce type de complexes sont également décrites. Le second chapitre décrit la synthèse par couplage bore-carbone d'une nouvelle famille de ligands ambiphiles, 2-picolylboranes. En fonction des substituants du bore, ces composés sont obtenus sous forme dimère ou monomère fermé par interactions datives donneur-accepteur, inter ou intramoléculaires. Le comportement en solution du 2-picolylBCy2 a été examiné attentivement. Un équilibre entre la forme dimère et monomère est mis en évidence. Des calculs théoriques valident nos conclusions. La coordination de ce ligand sur plusieurs précurseurs métalliques est étudiée. Un exemple rare de coordination pontante donneur->Ru-Cl->accepteur a été caractérisé dans le complexe [(p-cym)RuCl2(2-picolylBCy2)]. Dans le troisième chapitre, la synthèse par hydroboration d'une famille de ligands ambiphiles, 1,2-phosphinoethylborane, est décrite. Deux complexes de ruthénium neutres contenant ces ligands, ainsi que leur dérivés cationiques sont caractérisés. Des tests catalytiques préliminaires d'hydrosilylation du benzaldéhyde avec l'un des complexes cationiques ont montré la dégradation rapide du pré-catalyseur en un complexe ruthénacycle original. Sa réactivité avec un chloroborane et un chloroalane est étudiée
The present contribution deals with the use of ambiphilic molecules featuring both a Lewis base and a Lewis acid site, as ligands in organometallic chemistry. In the first chapter, a bibliographic study describes the behaviour of Lewis acids of group 13 in organometallic chemistry. Their role as co-catalysts is examined in order to better understand how the Lewis acid could behave in a complex featuring an ambiphilic ligand. The different coordination modes of those ligands are reviewed. The rare contributions dealing with the reactivity of those complexes are also examined. The second chapter describes the synthesis by carbon-boron coupling of a new family of ambiphilic ligands, namely 2-picolylboranes. Depending on the borane substituents, they are obtained as dimer or closed monomer via inter or intramolecular donor-acceptor dative interaction. The behaviour of 2-picolylBCy2 in solution is examined in details by NMR. An equilibrium between a dimer and a closed monomer form is evidenced. Theoretical calculations ascertain our conclusions. Coordination of this ligand to several transition metal precursors is studied. .

Les phosphures borane de lithium sont des espèces obtenues par déprotonation de phosphines borane secondaires par une base de type alkyllithien. L’analyse de ces composés, dont la structure est peu connue, par spectroscopie de résonance magnétique nucléaire multinoyaux a mis en évidence des interactions entre les atomes de lithium et d’hydrogènes du groupement borane et l’absence d’interaction PLi. En accord avec la structure de ces composés, une réactivité duale de P-nucléophile et de réducteur a été mise en évidence par réaction avec des dérivés carbonylés. L’issue de la réaction dépend des conditions imposées à la réaction : cinétique (produit de P-addition) ou thermodynamique (produit de réduction). Le processus de réduction a également conduit à des oligomères linéaires de phosphines borane. Dans une seconde partie, la synthèse de phosphines borane P-énantioenrichies a été effectuée par dédoublement dynamique thermodynamique de phosphures borane encombrés en présence d’amines énantiopures dérivées de 3-aminopyrrolidines, offrant pour la première fois un accès aux dérivés de configuration (S). Les phosphures borane de lithium sont des espèces obtenues par déprotonation de phosphines borane secondaires par une base de type alkyllithien. L’analyse de ces composés, dont la structure est peu connue, par spectroscopie de résonance magnétique nucléaire multinoyaux a mis en évidence des interactions entre les atomes de lithium et d’hydrogènes du groupement borane et l’absence d’interaction PLi. En accord avec la structure de ces composés, une réactivité duale de P-nucléophile et de réducteur a été mise en évidence par réaction avec des dérivés carbonylés. L’issue de la réaction dépend des conditions imposées à la réaction : cinétique (produit de P-addition) ou thermodynamique (produit de réduction). Le processus de réduction a également conduit à des oligomères linéaires de phosphines borane. Dans une seconde partie, la synthèse de phosphines borane P-énantioenrichies a été effectuée par dédoublement dynamique thermodynamique de phosphures borane encombrés en présence d’amines énantiopures dérivées de 3-aminopyrrolidines, offrant pour la première fois un accès aux dérivés de configuration (S)
Lithium phosphido-boranes are anionic species prepared by deprotonation of secondary phosphane-boranes using an organolithium base. Multinuclear NMR analysis of these poorly studied compounds evidenced lithium-hydrides interactions and absence of lithium-phosphorus one. According to their structure, these compounds develop a dual reactivity behaving as both P-nucleophile and reducing agent using carbonyl compounds as substrates. The issue of the reaction depends on the kinetic or thermodynamic control imposed to the reaction medium: P-addition or reduction, respectively. Linear polyphosphinoboranes have also been formed during the reduction process. In a second part, P-enantioenriched phosphane-boranes have been synthesized starting form sterically hindered phosphane-boranes using enantiopure amines derived from 3-aminopyrrolidine as chiral agents. This approach, involving a thermodynamic dynamic resolution process, leads for the first time to tertiary P-stereogenic phosphane-boranes, having the (S)-configuration

Dans le circuit primaire des réacteurs nucléaires à eau pressurisée, le bore participe au contrôle des réactions de fission. Le traitement de cette solution génère des déchets aqueux contenant une forte concentration en bore (de 1 à 3 mol/L). Le conditionnement de ces déchets à l'aide d'un ciment silico-calcique est compliqué par le fort pouvoir retardateur des ions borate sur l'hydratation du liant. Un traitement des déchets à la chaux est nécessaire pour précipiter les ions borate sous forme d'hexahydroborite. Cette stratégie, si elle limite le retard d'hydratation, ne le supprime pas. Par ailleurs, l'hexahydroborite est instable en milieu cimentaire et se convertit dans le temps en boroaluminate de calcium. Une autre approche pourrait consister à utiliser un ciment sulfoalumineux bélitique à forte teneur en ye'elimite. Ce liant présente en effet l'avantage de former en quantité importante des phases de type AFm et/ou AFt lors de son hydratation, phases qui peuvent incorporer des ions borate dans leur structure.Au cours de ce travail, l'hydratation de ciments sulfoalumineux par des solutions de borate de sodium a été étudiée au jeune âge et à plus long terme (sur une durée de 2 ans) dans l'objectif de préciser l'influence d'un ensemble de paramètres (pH du déchet, concentration en bore, taux de gypse du ciment) sur la vitesse d'hydratation du liant, la nature des hydrates formés, et les propriétés du matériau obtenu (résistance mécanique, stabilité dimensionnelle). Pour ce faire, une démarche analytique, procédant par complexification progressive des systèmes étudiés, a été mise en œuvre. Ainsi ont été successivement abordées la spéciation du bore en solution alcaline, l'étude des phases précipitant au sein des systèmes {CaO, B2O3, Na2O, H2O}, {CaO, B2O3, Al2O3, H2O} et {CaO, Al2O3, B2O3, SO3, H2O}, puis celle des pâtes de ciment gâchées avec une solution boratée simulant le déchet. L'approche expérimentale a été complétée par des modélisations thermodynamiques s'appuyant sur une base de données spécialement développée pour les besoins de l'étude.Il apparaît que le gypse joue un rôle primordial dans le contrôle de la réactivité du ciment. L'ajout de gypse fixe, par un mécanisme indirect, le pH de la solution interstitielle à une valeur proche de 11, ce qui favorise la précipitation transitoire d'un composé boraté faiblement cristallisé, l'ulexite. La dissolution des phases anhydres du ciment est alors fortement ralentie jusqu'à l'épuisement du gypse, conduisant ainsi à des retards de prise considérables. En l'absence de gypse, le retard à l'hydratation est de plus faible amplitude. Dans ces conditions, le pH de la solution interstitielle atteint des valeurs plus élevées, ce qui permet de déstabiliser rapidement l'ulexite. A plus long terme, les ions borate sont incorporés au sein d'une phase de type AFt, en solution solide avec les ions sulfate. Les résultats obtenus permettent de conclure que ce sont les ciments sulfo-alumineux contenant une faible teneur en gypse qui sont les plus adaptés au conditionnement de solutions à forte concentration en bore
In the primary circuit of pressurized water reactors, boron helps controlling the fission reactions. The treatment of this solution produces aqueous low-level or intermediate-level and short lived radioactive with a high boron concentration (up to 1 to 3 mol/L). Stabilization/solidification of such wastes with calcium silicate cement is complicated by the strong retarding effect of borate ions on cement hydration. A calcium hydroxide addition is required to precipitate borate ions into hexahydroborite. With this approach, the hydration delay is limited, but not suppressed. Besides, hexahydroborite is unstable in the cement paste and is progressively converted into a hydrated calcium boroaluminate phase. Another strategy may consist in using belite calcium sulfoaluminate cement with high ye'elimite content. During hydration, this binder forms indeed large amounts of AFm and/or AFt phases which can incorporate borate ions into their structure.In this work, hydration of calcium sulfoaluminate cement by borated solutions was investigated at early age, and over a 2-year period, in order to determine the influence of a set of parameters (boron concentration and pH of the waste, gypsum content of the cement) on the hydration rate of the binder, on the phase assemblage formed, and on the properties of the resulting material (mechanical strength, volume change). An analytical approach was adopted, based on a progressive increase in the complexity of the investigated systems. The focus was successively placed on the speciation of boron in alkaline solution, on the study of the phases formed within the {CaO, B2O3, Na2O, H2O}, {CaO, B2O3, Al2O3, H2O} and {CaO, Al2O3, B2O3, SO3, H2O} systems, and on the characterization of cement pastes prepared with a borate solution which mimicked the waste. The experimental approach was completed by thermodynamic modelling using a database specially developed for the needs of the study. Gypsum appears to play a key role in controlling the reactivity of cement. The gypsum addition sets, by an indirect mechanism, the interstitial solution pH at a value close to 11, which promotes the precipitation of a poorly crystallized borated compound, ulexite. Dissolution of the anhydrous phases is strongly slowed down until the exhaustion of gypsum, and major delays are observed. Without any gypsum, the hydration delay is shorter. Under these conditions, the pore solution pH reaches higher values after mixing. Ulexite is consequently quickly destabilized. Borate anions are then incorporated into a mixed borate/sulphate AFt type phase. It appears that calcium sulfoaluminate cements with low gypsum contents should be recommended to solidify borated solutions

När någon vill låna pengar kräver långivaren någon form av säkerhet för lånet. Ett sätt att säkerställa låntagarens betalningsförmåga är att någon går i borgen för låntagaren. Många människor har mycket knappa kunskaper om vad en borgensförbindelse innebär och åtagandet uppfattas bara som en formalitet. De lagregler som behandlar borgen är dispositiva, vilket innebär att det är avtalet som styr. Det är ofta en bank som är kreditgivare när ett borgensåtagande sluts och förbindelsen sker enligt bankens formulär. Banken är den starkare parten vid en borgensförbindelse eftersom den har mer kunskap om borgen än vad kredittagaren och borgensmannen har. Lagen är gammal och innehåller bara ett fåtal paragrafer där alla inte fyller någon funktion.

Mitt syfte med uppsatsen är att se om en enkel borgen vore ett bättre konsumentskydd för privatpersoner än vad proprieborgen är. Detta genom att se om bankerna informerar om skillnaden mellan en enkel borgen, proprieborgen samt generell borgen och vilka för- och nackdelar de olika borgensåtagandena har. Syftet är också att se om det skulle vara bättre med en tvingande lagstiftning till konsumentens bästa.

Jag har använt mig av den rättsdogmatiska metoden och undersökningen bygger på doktrinen, rättspraxis och de intervjuer som genomförts. Vidare har stor vikt lagts på de avtal som utfärdats av bankerna.

Vid proprieborgen kan banken vända sig till vilken den vill av borgensmannen och gäldenären för att infria sin fordran om en betalning inte inkommit vid avtalad tid. Vid en enkel borgen måste banken först kräva gäldenären på betalning innan den vänder sig till borgensmannen vilket blir en trygghet för denne. Numera är det bara proprieborgen och generell borgen som används i bankvärlden. Enkel borgen används inte eftersom bankerna inte ser den formen som en tillräcklig säkerhet. Generell borgen används inte när det är en privatperson som går i borgen utan bara när det gäller kommersiella förhållanden.

Under intervjuerna framkom det att enkel borgen skulle vara ett bättre alternativ för borgensmännen än vad en proprieborgen är. Vid en proprieborgen uppstår det en bekvämare situation för banken än vad det gör vid en enkel borgen. Därför anser jag att en enkel borgen skulle vara det enda alternativet då en borgensförbindelse skall ingås för att stärka konsumentskyddet och den skall vara tvingande till konsumenternas förmån.

Des borates fluores d'elements de transition 3d sont elabores en conditions hydrothermales sub ou super-critiques, tandis que des cristaux d'oxoborates croissent en bains mixtes d'oxydes et de fluorures. Une premiere, et unique, famille de borates fluores de terre rare est mise en evidence par synthese dans l'etat solide. Un caractere basique suffisamment marque des oxydes et fluorures de cations metalliques conditionne l'obtention de ces phases. Ce sont les nocerines m 3(bo 3)(oh,f) 3 (m = fe, co et ni), zn 2(bo 3)(oh) 0. 7 5f 0. 2 5, ln 3(bo 3) 2f 3(ln = sm, eu et gd), na 2ln 2(bo 3) 2o (ln = sm, eu et gd) et na 2ga 2(bo 3) 2o. Elles sont caracterisees au niveau structural par diffraction des rayons x sur poudre ou monocristal completee, dans certains cas, par la diffraction neutronique ou electronique. Les poudres de ni 3(bo 3)(oh,f) 3 precipitent dans une gamme de temperature etendue, 250-700\c ; leur cristallinite devient mediocre a basse temperature et leur surface specifique est elevee. Au dessous de la temperature de neel, deux transitions de spin-flop et un ferromagnetisme faible apparaissent respectivement pour co 3(bo 3)(oh,f) 3 et ni 3(bo 3)(oh,f) 3 ; les moments magnetiques s'ordonnent en trois sous-reseaux orientes a 120\ l'un de l'autre. En raison de leur mode d'obtention, les nocerines et le compose non centrosymetrique zn 2(bo 3)(oh) 0. 7 5f 0. 2 5 sont sujets a la substitution f oh qui est clairement mise en evidence par diverses techniques spectroscopiques : spectrometrie mossbauer du 5 7fe, resonance magnetique nucleaire du 1 9f et spectroscopie infra rouge. La fluorescence de eu 3 + dans les composes de terre rare ln 3(bo 3) 2f 3 et na 2ln 2(bo 3) 2o (ln = sm, eu et gd) est etudiee ainsi que la conduction ionique de na 2ga 2(bo 3) 2o qui devient significative a t>300\c. Un mecanisme de conduction par les ions na + est propose. La coordinence cationique des anions autres fluorure et oxyde est consideree et permet une etude cristallochimique unifiee des phases a charpente anionique mixte.

Poly(azolyl)borate ligands have proven to be extremely popular ligands since their introduction by Trofimenko in the late 60´s. The basic skeleton of these ligands involves usually three heterocycle units linked to a central boron apex via the azole nitrogen atoms. These ligands have been applied in diverse research areas such as homogeneous catalysis, materials science and bio-inorganic chemistry. More than 2000 papers, including books and reviews regarding the properties of these compounds, have been published. However, only a few synthetic methods for the preparation of such ligands have been reported and only a few examples of chiral borate-centred ligands are known. This thesis deals with the development of a novel synthetic route to tripodal borate ligands using B(NMe2)3 as the boron source. The mechanism of the reaction of this borane with azole heterocycles has been established by exploring the reactivity of a range of azoles. One of the major features of this new synthetic protocol is that it allows the formation of chiral tripodal ligands where the chiral groups are located either at the forth position at the boron atom or at the azole heterocycles. Coordination studies of the ligands have been undertaken and the metal complexes have been studied by a combination of spectroscopic and X- ray diffraction techniques. Preliminary application of the most representative ligands in the Asymmetric Transfer Hydrogenation (ATH) of prochiral ketones has been undertaken in collaboration with Prof. Dieter Vogt at the Technical University of Eindhoven.

Les travaux présentés ici s'inscrivent dans le cadre de l'activation de la liaison s-B-H par des complexes de ruthénium. Ils concernent l'étude du mode de coordination de composés boranes bifonctionnels de type L~BHR, au sein desquels L est une base de Lewis et R, un substituant sur l'atome de bore. Ces travaux ont pour objectif de montrer que le mode de coordination de ces composés est directement influencé par la base de Lewis utilisée ainsi que par la nature de l'espaceur présent entre la base de Lewis et le motif boré, en s'appuyant sur une étude préliminaire réalisée précédemment dans l'équipe. Dans cette optique, la famille des ligands phosphinoboranes de type P~BH(NiPr2) a été étendue et plusieurs espaceurs ont été considérés. La réactivité des composés à espaceur phénylméthylène, méthylphénylène et naphtylène vis-à-vis du précurseur [RuH2(. 2-H2)2(PCy3)2] a été étudiée en détail. Un quatrième composé de type phosphinoborane ne comportant pas d'espaceur et dans lequel les atomes de phosphore et de bore sont directement connectés a aussi été synthétisé et son comportement vis-à-vis du ruthénium a pu être mis en évidence. L'étude "miroir" des ligands phosphinoboranes à espaceur phénylméthylène et méthylphénylène démontre qu'une simple inversion des groupements fonctionnels phosphino et boryle au sein du ligand mène à un mode de coordination de ce dernier complètement différent. Dans un second temps, l'influence de la base de Lewis sur le mode de coordination du ligand a été mise en évidence par deux approches synthétiques différentes grâce à la complexation de boranes soufrés de type S~BH(NiPr2). La combinaison de plusieurs techniques complémentaires telles que la résonance magnétique nucléaire multinoyaux et à température variable, la diffraction des rayons X ainsi que les calculs théoriques m'a ainsi permis de définir finement les interactions mises en jeu entre le ligand et le fragment métallique et de mettre en évidence des modes de coordination inédits
In line with the general problem of the activation of B-H s bonds, this work is directly related to the study of the coordination mode of potentially bidentate ligands L~BHR, in which L is a Lewis base and R, a boron substituent. Herein, we show that the nature of the spacer linking the Lewis base and the sp² hybridized boron atom and the nature of the Lewis base itself can have a dramatic impact on the coordination mode of the ligand to the ruthenium center. Thus, based on a preliminary study made by our group, the family of phosphinoborane compounds P~BH(NiPr2) have been extended and several spacers have been considered. The coordination of phenylmethylene, methylphenylene and naphtylene spacer containing ligands to [RuH2(. 2-H2)2(PCy3)2] has been meticulously studied as well as a fourth phosphinoborane ligand featuring no spacer between the phosphino and boryl functions. Considering phenylmethylene and methylphenylene ligands, which result from the swapping of the phosphino and boryl groups, new and original coordination modes have been evidenced. Furthermore, the influence of the Lewis base was evaluated by two different synthetic approaches thanks to the complexation of sulfidoboranes S~BH(NiPr2) to ruthenium. The combination of several techniques as nuclear magnetic resonance, X ray diffraction and theoretical calculation allowed us to clearly define the interactions between the ligand and the metal and to highlight new coordination modes

La coordination de boranes monosubstitués RBH2 (R = aryl, amino) sur des complexes hydrure du ruthénium et pinceur d'iridium a été effectuée dans le cadre de notre étude sur les mécanismes d'activation des liaisons B-H de boranes par ces centres métalliques. Au cours de cette étude qui allie expérience et théorie, toute une gamme de complexes a été obtenue : des complexes de type borohydrure, s-borane et bis-s borane, au sein desquels le ligand conserve son intégrité. Un second niveau d'activation peut également être atteint. Dans ce cas, l'activation va jusqu'à la rupture d'une seule ou des deux liaisons B-H du ligand pour conduire respectivement à la formation de complexes de ruthénium de type boryl (LnM-BRH) et borylène (LnM=BR). Plusieurs complexes borylène terminaux du ruthénium RuHX(BR)(PZ3)2 ont ainsi été synthétisés et étudiés. Durant ma thèse, nous avons pu montrer que le niveau d'activation de la liaison B-H dépend exclusivement de la balance électronique autour de l'atome de ruthénium. Il existe un continuum d'activation de la liaison B-H. Nous avons pu notamment étudier plusieurs espèces dont la description non triviale correspond à un état arrêté du processus élémentaire d'addition oxydante du métal dans la liaison B-H. Enfin, il a été possible de transposer ces résultats à des complexes pinceur d'iridium, et d'obtenir pareillement une gamme variée de complexes d'iridium rendant compte de plusieurs scénarii d'activation de la liaison B-H d'un borane
In our general purpose to study the mechanisms governing the activation of the B-H bond of a borane by a metal center we have synthesised ruthenium hydride and iridium pincer complexes bearing a single monosubstituted borane RBH2 (R = aryl or amino). A range of complexes were studied experimentally and theoretically : borohydride, s-borane and bis-s borane complexes were obtained in which the ligand remains intact. A higher level of activation was observed, notably the cleavage of one or both of the B-H bonds, leading respectively to boryl (LnM-BRH) and borylene (LnM=BR) complexes. In particular, we have studied terminal borylene complexes RuHX(BR)(PZ3)2. A recurrent feature of my work has been control over the balance of electronics at the ruthenium center and its influence over the activation of B-H bonds. There is a continuum in the process of bond activation, in particular we identified different species whose descriptions were not obvious due to their nature as intermediates in the elementary step of oxidative addition of the metal into the B-H bond. Finally, we could transplant these results into the field of iridium pincer chemistry and obtain a diverse panel of iridium complexes where different scenarii for B-H bond activation of a borane are possible

Dans le premier chapitre, une étude bibliographique présente les rôles joués par les acides de Lewis du groupe 13, principalement du bore, en chimie organométallique. Même si dans ce domaine, ils sont principalement utilisés comme co-adduit, de rares exemples montrent que placés au sein d'un complexe métallique, ils peuvent (a) réaliser l'activation intramoléculaire d'une liaison M-X, (b) servir de point d'ancrage pour approcher un substrat riche en électrons du centre réactif et (c) interagir directement avec le métal lui-même.

Dans le second chapitre, la synthèse et l'étude de la structure adoptée par les ligands ambiphiles sont discutées. Les facteurs régissant les préférences structurales des composés mono, di et triphosphine-borane sont étudiés.

Dans le troisième chapitre, l'étude de la coordination de composés ambiphiles monophosphine-borane PB est réalisée vis-à-vis de complexes plan carré d8 ML4. Deux modes de coordination sont mis en évidence présentant un acide de Lewis non impliqué dans la coordination P→M, puis en interaction avec un chlorure porté par le métal P→M-Cl→B.

Dans le quatrième chapitre, l'utilisation des composés diphosphine-borane PBP permet de mettre en évidence un troisième mode de coordination faisant apparaître une interaction M→B pour des complexes de rhodium, platine et palladium. L'analyse de cette interaction montre une forte dépendance vis-à-vis de la nature du métal.

Enfin, dans le cinquième chapitre la variation de la nature du précurseur métallique, ainsi que la modulation de l'acidité de Lewis du site accepteur conduisent à deux complexes d'or présentant une interaction originale Au-B par la coordination des composés mono-phosphine-borane PB.

L'ensemble de ce travail a été effectué en associant études expérimentales et études théoriques réalisées par Karinne Miqueu de l'Université de Pau et des Pays de l'Adour.

Zinc borate is a flame retardant additive used in polymers, wood applications and textile products. There are different types of zinc borate having different chemical composition and structure. In this study, the production of zinc borate that had the molecular formula of 2ZnO.3B2O3.3,5H2O was studied. The aim of this study was to investigate the effects of reaction parameters on the properties of zinc borate that had been synthesized by the reaction of boric acid and zinc oxide at the existence of the seed crystals and to determine the optimum experimental conditions for zinc borate production reaction. Reaction kinetics was also investigated to find a suitable kinetics model. The effect of boric acid to zinc oxide ratio -H3BO3:ZnO ratio- (3:1, 3.5:1, 5:1 and 7:1), the particle size of zinc oxide (10µ
m and 25µ
m), stirring rate (275 rpm, 400 rpm, 800 rpm and 1600 rpm), temperature (75°
, 85°
and 95°
) and size of seed crystals (10µ
m and smaller size) on reaction rate, reaction completion time, composition and particle size distribution of zinc borate were investigated. Experiments were performed in a continuously stirring, temperature controlled batch reactor with a volume of 1.5L. During the experiments samples were taken to be analyzed in regular time intervals. The analyses of the samples gave the concentration change of zinc oxide and boron oxide in the solid as well as the conversion of zinc oxide to zinc borate with respect to time and the rate of reaction was calculated. The products were also analyzed for particle size distribution. The experimental results showed that the reaction rate increased with the increasing H3BO3:ZnO ratio, particle size of zinc oxide, stirring rate and temperature. The reaction completion time was also decreased by increasing H3BO3:ZnO ratio, stirring rate and temperature. The particle size of final product, zinc borate, decreased with increasing stirring rate and size of zinc borate used as seed and increased with increasing particle size of zinc oxide used as reactant. The average particle sizes of the final product zinc borates synthesized at the end of the experiments were ranged between 4.3 µ
m and 16.6 µ
m. The zinc borate production reaction was mainly fitted the unreacted core model for the case of diffusion through product layer controls.

As the developed world seeks to reduce the dependence upon fossil fuels, amine boranes have received increased interest as a clean, stable hydrogen source. This thesis sought to scrutinise the mechanism of amine borane dehydrocoupling proposed by Hill and provide quantitative evidence for the dependence of dehydrocoupling activity upon identity of the metal centre. This work led to a refined mechanism, incorporating proton-assisted β-hydride elimination steps, occurring via potentially concerted processes. A pathway to account for the previously unreported reactivity of [R2N-BH2]2 to ultimately afford [HB(NR2)2] is also included. A dependence upon the identity of the metal centre on the dehydrocoupling activity was found, identifying a decrease in reactivity with increasing ionic radius and decreasing cation charge density as each group is descended. This thesis showed that the mechanism of secondary amine borane dehydrocoupling by d0 reagents is complex, suggesting that a generic mechanism which fully describes dehydrocoupling of all amine boranes would be too much of an oversimplification.

Dans le premier chapitre, une étude bibliographique présente les rôles joués par les acides de Lewis du groupe 13, principalement du bore, en chimie organométallique. Dans le second chapitre, la synthèse et l’étude de la structure adoptée par les ligands ambiphiles sont discutées. Dans le troisième chapitre, l’étude de la coordination de composés ambiphiles monophosphine-borane PB est réalisée vis-à-vis de complexes plan carré d8 ML4. Dans le quatrième chapitre, l’utilisation des composés diphosphine-borane PBP permet de mettre en évidence un troisième mode de coordination faisant apparaître une interaction M→B pour des complexes de rhodium, platine et palladium. Enfin, dans le cinquième chapitre la variation de la nature du précurseur métallique, ainsi que la modulation de l’acidité de Lewis du site accepteur conduisent à deux complexes d’or présentant une interaction originale Au-B par la coordination des composés mono-phosphine-borane PB
In the first chapter, a bibliographic study describes the differing behaviour of the Lewis acids of group 13 in particular boron, in organometallic chemistry. In the second chapter, the synthesis and study of the structures adopted by the ambiphilic ligands themselves are discussed. In the third chapter, the coordination of the monophosphane-borane ligands with square planar d8 ML4 complexes is described. In the fourth chapter, the use of the diphosphane-borane ligands allows the description of a third coordination mode, in which the borane moiety interacts directly with the metal. The characterisation of rhodium, platinum and palladium complexes shows a variation of the strength of the interaction depending on the metal. Finally, in the fifth chapter, the use of a gold precursor complex and monphosphine-borane ligands of increasing boron Lewis acidity allows the description of an original Au-B interaction

Les travaux décrits dans ce manuscrit de thèse concernent l’exploitation des interactions acide-base de Lewis entre deux partenaires organophosphorés et organoborés. Quatre types d’interactions ont été particulièrement au cœur de notre étude, allant de la frustration de la liaison P-B à la formation de complexes acide base de Lewis fortement liés. L’étude de ces interactions, couplée à des outils de physico-chimie organique et de chimie théorique, nous ont permis, non seulement de comprendre les paramètres clés de la réactivité mais également de mettre en avant de nouvelles voies de synthèse. Dans un premier temps, notre étude s’est portée sur l’hydrogénation de composés insaturés par les Paires de Lewis Frustrées (FLP). Ainsi, l’origine de l’incapacité des P/B à réduire les accepteurs de Michael a été expliquée par des mesures cinétiques de la nucléophilie et de la basicité de Lewis de phosphines encombrées. Dans une seconde partie, l’hydricité de complexes de phosphine borane (PBs) variées a été mesurée, nous permettant d’établir une échelle de prédiction de la réduction de divers électrophiles en présence de ces donneurs d’hydrure ioniques. Cette étude nous a conduit à considérer les PBs comme substrats dans des réaction de borylation intramoléculaire impliquant BH3 comme source de bore. Cependant, des résultats inattendus ont mis en exergue une migration prépondérante à la borylation lors de la réaction entre les PBs et un acide de Lewis, donnant accès à une nouvelle familles de PBs possédant un atome de bore électro-déficitaire. Des études cinétiques couplées à une étude par DFT ont permis de rationaliser la réactivité observée. Enfin, l’exploitation des interactions réversibles entre une phosphine secondaire et un acide de Lewis organique ou métallique nous ont permis de contrôler la régiosélectivité lors de l’hydrophosphination d’alcènes 1,1-disubstitués par les diarylphosphines. Nos études mécanistiques soutiennent fortement l’implication d’un carbocation comme intermédiaire réactionnel
The research in this thesis describes the exploration of the Lewis-acid Lewis-base interactions between organophopshine and organoborane compounds. We focused our attention on four types of interactions going from frustrating to stong P-B bonds. Our understanding of these interactions is based on detailed kinetics and computational calculations, allowing us to find a new reactivity of these species. In a first part, we studied the metal-free hydrogenation of unsaturated compounds using Frustrated Lewis Pairs (FLPs). Based on the measurement of the nucleophilicity and the Lewis basicity parameters of sterically hindered phosphines, we were able to explain reasons of the failure of P/B FLPs to catalyse the hydrogenation of Michael acceptors under H2. In the second chapter, we employed the Mayr’s linear-free energy relationship to measure the hydricity of various phosphine borane complexes (PBs) and compare their reactivity to commons hydride donors. Based on these kinetic parameters, we next turned our attention to investigate the effect of a strong Lewis acid, (B(C6F5)3), to prevent the expected intramolecular borylation of PBs to take place. By combining kinetic and computational investigations, we have been able to understand factors controlling this reaction. In the last chapter, we reported on the regioselective organocatalytic Markovnikov hydrophosphination of aryl alkenes. Importantly, we highlighted that the reversible formation of a phosphine-Lewis acid complex is in the core of the catalytic process. Mechanistic investigations support the formation of a carbocation in the catalytic cycle

Le besoin accru de stockage d'énergie via Li- et batteries Na-ion nécessite une recherche continue de nouveaux matériaux de cathode ayant une densité énergétique plus élevée et étant sûr et durable. Ainsi, nous avons exploré des composés à base de borate capables de réagir avec Li/ Na-ions de manière réversible, soit par le biais de réactions topotactic- ou de conversion. Nous nous sommes concentrés sur les candidats avec des anions polyborate, qui devraient montrer des potentiels redox élevés par rapport aux matériaux à base BO3. Li6CuB4O10 utilisant comme composé modèle, nous avons montré la possibilité d'obtenir des potentiels d'oxydo-réduction de 4.2 et 3.9 V par rapport à Li pour l'α- et ß polymorphes. L'activité redox a été rationalisée par spectroscopie EPR et calculs DFT. Nous révélons en outre la relation structurelle / synthétique entre les deux polymorphes et montrons une conductivité ionique élevée de 1.4 mS / cm à 500 °C pour une forme de HT d'-Li6CuB4O10. De plus, nous avons pu préparer deux pentaborates 3d-métal nouveau sodium Na3MB5O10 (M = Fe, Co). M = Fe, nous avons observé une intercalation Na réversible à un potentiel moyen de 2.5 V par rapport à Na, alors Na3CoB5O10 avéré être inactif électrochimique. Dévier à partir de composés d'insertion / désinsertion classiques, nous avons étudié la électrochimique entraîné la réaction d'un oxyborate bismuth Bi4B2O9 contre Li par des mesures électrochimiques combinées avec XRD et TEM. Nous avons constaté qu'il est possible de faire défiler ce matériau réversible entre 1.7 et 3.5 V avec un potentiel redox d'environ 2.3 V par rapport à Li avec seulement 5% en poids de carbone et une faible polarisation ~ 300 mV
The increased need of energy storage via Li- and Na-ion batteries requires a continuous search for new cathode materials having higher energy density and being safe and sustainable. Thus, we explored borate based compounds capable of reacting with Li/ Na-ions in a reversible way either through topotactic- or conversion reactions. We focused on candidates with polyborate anions, that are expected to show elevated redox potentials compared to BO3 based materials. Using Li6CuB4O10 as a model compound we showed the possibility to achieve redox potentials of 4.2 and 3.9 V vs Li for the α- and β-polymorphs. The redox activity was rationalized through EPR spectroscopy and DFT calculations. We further reveal the structural/ synthetic relation between the two polymorphs and show a high ionic conductivity of 1.4 mS/cm at 500°C for a HT form of α-Li6CuB4O10. Moreover we were able to prepare two new sodium 3d-metal pentaborates Na3MB5O10 (M = Fe, Co). For M = Fe we observed a reversible Na intercalation at an average potential of 2.5 V vs Na, whereas Na3CoB5O10 turned out to be electrochemical inactive. Deviating from classical insertion/ deinsertion compounds, we studied the electrochemical driven reaction of a bismuth oxyborate Bi4B2O9 versus Li through electrochemical measurements combined with XRD and TEM. We found that it is possible to reversible cycle this material between 1.7 and 3.5 V with an redox potential of ~2.3 V vs Li with only 5wt% carbon and a small polarization ~300 mV. Owing to the complexity of 3d-metal borate chemistry encountered through this PhD, the chances of having a borate based positive electrode for next generation Li-ion batteries is rather slim

La première synthèse d'un carbène N-hétérocylique borane (NHC-borane) stable a été réalisée en 1993. Pourtant la découverte de leur vaste potentiel en chimie n'a réellement débuté qu'à partir de 2007. Les domaines d'application de ces composés du bore, stables et facile d'accès, s'étendent de la synthèse d'organique (réduction d'imine, hydroboration de liaisons multiples, médiateurs radicalaires) à la chimie organométallique (couplage de Suzuki-Miyaura) en passant par la chimie des polymères (amorceurs ou co-amorceurs de photopolymérisation). L'objectif de ce projet aura été d'étendre l'application des NHC-boranes dans deux différents systèmes de photopolymérisation. Le premier système étudié a permis l'obtention de matériaux acrylates contenant des nanoparticules métalliques à partir d'un seul composé dans un processus monotope. Le second système visait l'amorçage de réactions de polymérisation en émulsion sous irradiation visible. Nous avons utilisé le pouvoir réducteur des NHC-boranes pour former des nanoparticules d'or ou d'argent directement dans des monomères acrylates. Puis, la formation par le NHC-borane de la matrice polymère contenant les nanoparticules est déclenchée par une irradiation UV. L'analyse par HRTEM a mis en évidence des petites nanoparticules (ca. 10 nm) emprisonnées dans la matrice. Cette méthode présente une approche encore plus directe pour obtenir ce type de matériau plutôt que les procédés multi-étapes déjà existants. Le second système étudié utilise pour la première fois un NHC-borane comme co-amorceur de la polymérisation du styrène ou du méthacrylate de méthyle en émulsion sous irradiation visible. Il en résulte des latex stables, composés de particules de tailles moyennes contrôlées formés à partir de quantités de tensioactifs inférieures à celles utilisées dans des systèmes photoamorcés déjà décrits. Ces systèmes amorcés par une irradiation visibles pourraient être intéressants pour réduire les coûts énergétiques des synthèses et éviter la dégradation de composés thermo- ou UV- fragiles
Despite the first synthesis of stable N-heterocyclic carbene (NHC)-boranes occurring as early as 1993, the widespread exploration of their potential in chemistry truly began only in 2007. The versatility of these stable and easily accessible boron compounds has led to their application in organic reactions (imine reduction, multiple bond hydroboration, radical reductions), organometallic reactions (Suzuki- Miyaura cross coupling) and polymerization (initiation or co-initiation of polymerization). The aim of my project was to extend the applicability of NHC-boranes to two different photopolymerization systems. The first aimed to synthesize polymer matrices containing metal nanoparticles in a one pot, one reactant process. The second aimed to perform emulsion polymerizations initiated by visible light. In the first system, the reductive capacity of NHC-boranes was used to generate gold or silver nanoparticles directly in acrylate monomers. Then, the initiating ability of NHC-boranes was triggered by UV light to form the polymer matrix containing embedded nanoparticles. Characterization by HRTEM showed small nanoparticles (ca. 10 nm) successfully contained within the matrix. This method represents a more straightforward approach than obtaining such materials through the multistep processes already reported in literature. In the second system, NHC-boranes were employed for the first time as co-initiators in visible light initiated emulsion polymerization styrene and methyl methacrylate. Stable latexes were generated with controllable particle sizes at lower surfactant concentrations than those used in related light-initiated systems. Such visible light-triggered initiation systems are interesting for reducing energy consumption and avoiding degradation of heat- or UV-sensitive materials

Le sujet de la thèse initié dans le cadre de l'ANR UV-Borate s'inclut dans le projet UV-Conversion labellisée par 2 pôles de compétitivité (Matériala - Lorraine - et Route des lasers - Aquitaine -) soumis à l'ANR en 2011. Les études se portent particulièrement sur les borates YxLaySc4-(x+y)(BO3)4 (LYSB) et YAl3(BO3)4 (YAB), cristaux Optiques Non Linéaires (ONL) possédant la même structure cristallographique (R32). La croissance de ces cristaux est effectuée par les collaborateurs industriels et universitaires de l'ANR. Ces deux matériaux présentent en effet des possibilités de conversion de fréquence jusqu'à des longueurs d'onde λ < 300 nm, de plus une non hygroscopicité procure une plus grande durée de vie des échantillons et par conséquent un net intérêt pour les applications industrielles. L'endommagement laser étant lié à l'absorption et ainsi, en partie, aux impuretés, une étude de la qualité cristalline et de l'homogénéité de nos cristaux a été effectuée. Les résultats ont permis de relier des défauts de structure (dislocations et etch pits) à la croissance de la maille rhomboédrique via des caractérisations par ombre portée (Photography Schlieren) et par attaque chimique suivi d'une observation par microscopie optique, MEB et MFA. Par ailleurs, des études théoriques et expérimentales d'accord de phase (détermination de θ et φ) lors de conversions de type I principalement ont été réalisées sur les cristaux de YAB, LYSB ainsi que sur des cristaux de référence tel que β-BaB2O4 (β-BBO). L'aspect de l'endommagement laser dans les matériaux ONL a été abordé dans les locaux de l'Institut Fresnel de Marseille au sein de l'équipe Interaction Laser Matière (ILM) sur des échantillons de Li2B4O7 (LTB). L'équipe a effectivement développé un dispositif de mesure de la probabilité d'endommagement laser et de mesure de tenue du seuil d'endommagement laser des matériaux optiques. Par ailleurs, un effort a été mené dans la conception d'un dispositif de mesure de la transmission optique et absorption à température ambiante et aux basses températures afin de révéler des défauts absorbants. Des premiers résultats ont été obtenus et discutés sur des échantillons de β-BBO et LYSB.

The 'enigmas' dealt with in Part 1 (Chapters 1-4) are illusory, arising largely from the apparent inability of many of his critics to understand much of Borges' work. However, the discussion of his widely appreciated wit in Chapter 1 shows that this is sometimes the fault of Borges himself. He once proclaimed his intention to conceal the true nature of some of his fictions so that only 'a very few' of his readers should understand them. Fortunately, his attempts at concealment were not always successful; but some of his critics seem to have been misled by them. Chapters 2-4 deal with characteristics that appear to be less widely appreciated. Chapter 2 discusses the importance of Borges' obsession with death; chapter 3 deals with what he called 'the most precious gift, doubt'; and chapter 4 illustrates Borges' humility and his aversion to arrogance; but all three chapters demonstrate that Borges' critics have often failed to acknowledge these characteristics. Chapters 2 and 3 show that many of his poems make clear the importance of some of these factors. Borges regarded himself primarily as a poet, and published many more books of poetry than prose; however, comparatively little attention has been paid to this aspect of his work. Part 2 of the thesis (chapters 5 and 6) deals with the enigma which Borges himself presents. This is no illusion. It stems mainly from some of his seminars, lectures and non-fictional pieces, which are shown to be rife with inaccuracies, contradictions, and poor preparation. They raise many questions about the depth of Borges' learning, and about his academic rigour. Part 1 suggests answers, while Part 2 despairs of answers. A number of the quoted texts were published originally in English; I have no Spanish, and the remaining texts are quoted in translation.

Les complexes carbènes N-hétérocycliques-boranes (NHC-Boranes) sont de nouvelles structures dont l’application en synthèse n’a pas été explorée. Notre but a été de nous intéresser à la réactivité de ces dérivés en étudiant l’influence de la complexation du ligand NHC sur l’atome de bore. Le premier aspect de cette recherche consistait à utiliser les complexes NHC-boranes comme nouveaux médiateurs radicalaires. Les calculs théoriques ont montré que la valeur de la BDE de liaison B-H de ces complexes était suffisamment faible pour pouvoir les utiliser comme réducteurs radicalaires dans la réaction de désoxygénation de Barton-McCombie. Ainsi, nous avons pu réaliser la réduction de divers xanthates secondaires avec des rendements satisfaisants. Nous avons ensuite montré que les complexes NHC-boranes pouvaient se comporter comme des réducteurs ioniques en réduisant des halogénures et de triflates aromatiques catalysées par le palladium. Par ailleurs, nous avons étendu le champ d’application de ces complexes aux couplages C C. Les NHC-boranes substitués sont donc de nouveaux partenaires pour la réaction de couplage de Suzuki-Miyaura. Pour finir, grâce à une nouvelle réactivité, il est possible de synthétiser des complexes NHC-boranes fluorés en générant un cation borénium stabilisé par un ligand NHC
N-heterocyclic carbenes boranes (NHC-Boranes) complexes are novel structures whose reactivity —especially organic— has not been explored. Our goal was to investigate the influence of the NHC complexation on the reactivity at the boron atom. We focused first on radical reactions. Computational studies showed that the values of the B-H BDE of these complexes are low enough to use them as radical hydrogen donors in the Barton-McCombie deoxygenation of xanthates. We thus reported that two NHC-BH3 complexes reduce different secondary xanthates in acceptable yields under the Barton-McCombie conditions. Then, we found that palladium could mediate the reduction of a variety of aryl halides and triflates by using NHC-boranes complexes as an hydride donors. In addition, we found that, by changing the borane, palladium could catalyze sp2–sp2 and sp2–sp3 C–C couplings in good to excellent yields. NHC-boranes complexes are hence a family of new boron partners for Suzuki-Miyaura couplings. Finally, we discovered a new reactivity by generating a borenium cation stabilized by the NHC ligand. This reactivity allows us to synthesize fluorinated NHC-boranes complexes

Polykristallines Sr3Gd2[BO3]4 (SGB) konnte mithilfe einer stöchiometrischen Mischung aus SrCO3, Gd2O3 und B2O3 durch zweimaliges Sintern bis 1.350 °C phasenrein erzeugt werden. Ein Exzess von 3 Ma% B2O3 musste der Mischung beigesetzt werden, um das an B2O3 gebundene Wasser auszugleichen [125]. Kristalle des SGB ließen sich mit verschiedenen Orientierungen erfolgreich mit dem Czochralski-Verfaren synthetisieren. Unter Einsatz eines arteigenen, b-orientierten Keimes, einer Translation von 1 mm/h und einer Rotation von 4 /min konnten Kristalle mit guter Qualität bei hoher Erfolgsrate produziert werden. Bei den gezüchteten Kristallen waren keine Segregationserscheinungen zwischen Gadolinium und Strontium feststellbar. Jedoch weist das Auftreten von Fremdphasen (vor allem Gd2O3) in wenigen Kristallen auf eine mögliche, geringfügige Bevorzugung des Sr in der Struktur hin. Die Härte des Materials ist mit ca. 5,5 nach Mohs bestimmt, die Dichte mit 5,15(1) g/cm3. SGB ist nicht hygroskopisch, lässt sich aber in mineralischen Säuren lösen. Die Schmelztemperatur konnte mit 1.461+/-5 °C bestimmt werden. Einkristallines SGB besitzt ein Transmissionsfenster zwischen 215-3.450 nm. Das entspricht einer Bandlücke von 5,4 eV. In diesem Bereich werden über 80% des eingestrahlten Lichtes transmittiert. Im ultravioletten Spektrum finden sich für Gd charakteristische Absorptionsbanden, die durch Elektronenübergänge erzeugt werden. Im mittleren Infrarotbereich lassen sich um die Absorptionskante mehrere Absorptionsbanden, deren Ursache ungeklärt ist, feststellen. Sie stehen offensichtlich im Zusammenhang mit dem Auftreten von [BO3]3- -Gruppen, da sie auch bei anderen Boraten, wie dem Ca4Gd[O|(BO3)3] [99], vorkommen. Gepulvertes SGB weist im Bereich von 550-1.600 cm-1 zahlreiche Absorptionsbanden, die auf verschiedene Schwingungen innerhalb der [BO3]3- -Gruppe zurückgeführt werden können, auf. Es folgen zu kleineren Wellenzahlen hin vermutlich Sr-O- und Gd-O-Schwingungen. Die thermische Ausdehnung von SGB-Kristallen ist anisotrop sowohl zwischen den kristallographischen Richtungen a, b und c als auch über die Temperatur innerhalb einer Richtung. Sie kann im Mittel zwischen 150-830 °C mit alpha11=18,1(2)*10-6/K, alpha22=8,9(3)*10-6/K und alpha33=20,3(4)*10-6/K angenommen werden. Die Ausdehnungskurven deuten mehrere Effekte an, wobei ein Effekt im Bereich von 450-700 °C und vermutlich zwei weitere im Bereich von 800-1.000 °C zu beobachten sind. Aufgrund der Stetigkeit der Kurve ist wahrscheinlich von Phasenübergängen höherer Ordnung auszugehen. Zur Struktur des SGB konnten wichtige Grundverständnisse gewonnen werden. So lässt sich die Struktur bei Raumtemperatur nicht durch eine orthorhombisch zentrische Metrik beschreiben, da die Einzelreflexe bei Einkristallmessungen eine Aufspaltung im Bereich von 0,1 ° zeigen. Dies deutet auf das Vorhandensein von Zwillingen und auch auf eine mögliche monokline Metrik hin. Es fällt dabei besonders auf, dass die Aufspaltung mit zunehmendem Theta-Winkel nicht größer wird, so dass auch andere Phänomene für die Reflexaufspaltung verantwortlich sein könnten. Dennoch ergeben die ermittelte Raumgruppe Pnam, die zugehörigen Gitterparameter (a0=0,7408 nm, b0=0,8757 nm, c0=1,6057 nm) und Atomkoordinaten ein vereinfachtes Modell zur Veranschaulichung der Struktur. Hoch- und Raumtemperaturstruktur sind bis 700 °C unter Annahme des vereinfachten Modells isomorph, wobei die Gitterparameter entsprechend der Ausdehnung vergrößert sind. Die Gd- und Sr-Positionen sind untereinander mischbesetzt. Außerdem deutet sich eine Positionsfehlordnung einer Sauerstoff-Position an, der Ligand eines Borions auf spezieller Lage ist. Hinweise auf die korrekte Struktur liefern die entdeckten Phasenübergänge und Hochtemperatur-Einkristalldaten. Der in der Dilatometrie entdeckte Effekt zwischen 450-700 °C korreliert mit dem Rückgang der Reflexaufspaltung, die bei ca. 700 °C nicht mehr sichtbar ist, wobei sich dieser Rückgang vermutlich von Raumtemperatur bis 700 °C erstreckt. Damit bestätigt sich, dass der erst genannte Effekt als Phasenübergang höherer Ordnung aufgefasst werden kann. Die festgestellte Positionsfehlordnung von Sauerstoff verringert sich mit steigender Temperatur. Die Mischbesetzung ändert sich ebenfalls bis ca. 500 °C. Beide Effekte sowie auch größeren Schwingungsellipsoide der Sauerstopositionen um die allgemeine Borlage sind vermutlich Ausdruck für den stattfindenden Phasenübergang und verstärken die Annahme einer Zwillingsbildung.

This thesis reports the investigation of molecular materials for hydrogen storage applications with a particular emphasis on alkali-metal amidoboranes. I have developed new routes for the synthesis of $alpha$-LiNH$_{2}$BH$_{3}$ and NaNH$_{2}$BH$_{3}$, and have studied their hydrogen storage properties by thermogravimetric analysis, variable temperature X-ray and neutron diffraction and inelastic neutron scattering. I report the synthesis and full structural characterization of two new materials, KNH$_{2}$BH$_{3}$ and $beta$-LiNH$_{2}$BH$_{3}$, and have performed initial studies on a tetragonal phase of a variant of LiNH$_{2}$BH$_{3}$ with a preliminary structure solution. I have also performed variable temperature neutron diffraction on ammonium borodeuteride, ND$_{4}$BD$_{4}$, and report the full structural characterisation of the three phases identified as a result of these measurements. Furthermore, variable temperature inelastic neutron scatting (INS) measurements were performed on ammonia borane, NH$_{3}$BH$_{3}$, and the results are discussed in terms of crystallographic phase changes.

Two systems of glasses have been studied: soda-lime-silica and alkali borate glasses. Vitreous boron oxide was included as a standard for comparison with alkali borates. Silica and irradiated vitreous silica were included for low Q diffraction studies as comparison with previous results.