No description available.

No description available.

No description available.

Silicon has emerged as a promising alternative to traditional graphite as an anode material in battery technology, primarily due to its high theoretical capacity and abundance. However, its application is hindered by significant challenges, including severe volume expansion in the active material (~275%) during cycling, which can lead to a series of electrode failure issues. Polymer binder plays an essential role in addressing these challenges as it accommodates silicon's volume expansion and the rearrangement of particles. This work conducted an analysis of how different binders influence mechanical and electrochemical properties of silicon electrodes. Our findings are supported by a series of experiments, aimed at addressing the challenge of silicon volume expansion and improving the durability and efficiency of silicon-based anodes. Water-soluble polyacrylic acid (PAA) has emerged as a promising binder material for silicon anodes, with lithium hydroxide (LiOH) frequently added to improve the rheological properties of the slurry. However, literature presents varying results regarding the electrochemical performance of batteries incorporating LiOH in PAA binders. In addressing these discrepancies, our research investigates the role of LiOH in PAA, defining its impact through two primary factors: lithium-ion concentration and pH level. Our analysis involved conducting cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests, which confirmed our hypothesis that the addition of Li+ ions improves ion transport. Regarding pH, an optimal middle-ground pH level is identified, balancing the advantages shown at both lower and higher pH ranges. Despite the observed benefits of water-soluble PAA binder, such binders frequently result in uneven carbon distribution in coating, attributed to the poor wettability of nano-carbon in water. Consequently, the next portion of this work revisits the use of a traditional NMP (N-Methyl-2-pyrrolidone) soluble binder, PVDF (polyvinylidene fluoride), known for its widespread application in battery technology. However, PVDF-based silicon anodes often exhibit poor cycling performance. To address this issue and enhance the binder's flexibility, we attempted to chemically modify PVDF by incorporating carboxylic acid (-COOH) groups and reducing the polymer chain length. Despite these efforts, the experimental results did not show an improvement in cycling performance. The findings suggest that the deteriorated performance may be due to a weakened adhesion to the current collector for short-chain polymers. We then explore additional binder systems in an attempt to improve Si electrode performance. Our previous research suggests a trade-off between flexibility and adhesion in shortened polymers. To further verify this, we investigate the effect of two commercially available short-chain polymer binders, namely Jeffamine D-2000 and PAA(2000). Next, in order to mitigate the adverse effects of short polymer chain lengths on mechanical performance, we adopt an adhesion layer between the bulk electrode layer and the current collector. Finally, we evaluate several binders known for their promising results in other battery systems, including polyacrylonitrile (PAN), polyvinylidene fluoride-hexafluoropropylene (PVDF-HFP), and polyimide (PI). A series of mechanical and electrochemical characteristics of the as-mentioned binders are investigated. The findings confirm that shorter polymer chain length leads to a weaker adhesion between the electrode coating and the current collector. Additionally, we discovered that introducing an adhesion layer can enhance the cycling stability of silicon anodes.

Li Zehou 李泽厚 (1930 - ) est l’une des plus importantes figures de la philosophie chinoise contemporaine. A l’issue d’un itinéraire philosophique qui le conduit de Changsha à Beijing, puis aux Etats-Unis, où il enseigne à Colorado College, Li Zehou œuvre à la création d’une philosophie chinoise, réactualisant l’héritage traditionnel chinois par l’intégration de la philosophie. Lors de ce parcours, il étudie l’histoire de la pensée chinoise, devient le plus éminent spécialiste de l’esthétique chinoise, et s'attelle à la critique de la Critique de Kant. Depuis les années 2000, son travail se concentre sur le champ de l’ontologie, au sein duquel il propose sa propre théorie, “L’ontologie anthropologico-historique”.Cette étude est une exploration de l’ontologie de Li Zehou, mais dans une perspective qui dépasse les affirmations de son auteur. Grâce à une méthode multi-focale, nous travaillons à décrire, le plus précisément possible, quels sont les engagements ontologiques réels de Li Zehou. D’abord, à partir de son traitement des philosophies de Marx, Kant et Dewey, quelles sont les options ontologiques propres à la philosophie qu’il admet, et quelles sont celles qu’il rejette? Ensuite, quelles créations ontologiques découvrons-nous en parcourant ses textes, et en offrant une voix philosophique française à ce philosophie chinois ? Enfin, comment l’ontologie, et plus généralement la philosophie de Li Zehou, se situe-t-elle sur le plan philosophique, dans le monde du “sens philosophique” ? Quelles cohérences, quelles résonances, quelles différences, faut-il identifier par rapport aux enseignements chinois et aux courants philosophiques ? / Li Zehou 李泽厚 (1930 - ) is one of the foremost figure of contemporary Chinese philosophy. He is at the end of a philosophical path that lead him from Changsha to Beijing and to the United States of America, where he teaches at Colorado College, and is working on the creation of a Chinese philosophy, reactualizing the Chinese traditional legacy through the integration of philosophy. Simultaneously, he studied the history of Chinese philosophy, became the most eminent specialist of Chinese aesthetics and criticized Kant’s Critique. Since the 2000s, he has focused his work on the field of ontology, in which he has proposed his own theory, “The anthropologico-historical ontology”.This study is an exploration of Li Zehou’s ontology, but in a perspective that exceeds the assertions of the author. Thanks to a multi-focal methodology, we will describe as thoroughly as possible what Li Zehou’s real ontological commitments are. At first, starting from his study of Marx, Kant, and Dewey’s philosophies, we’ll seek to identify which ontological options he admits and which he rejects, among the traditional philosophical ones. Then, we’ll focus on his own ontological creations, by analyzing his texts and giving him a French philosophical voice. Finally, we will situate his ontology and his philosophy in the philosophical plan, within the world of “philosophical meaning”. What consistencies, resonances and differences should we identify as regards the Chinese teachings and philosophical movements?

No presente trabalho foi realizado um estudo comparativo entre as ligas AA7050- T7451 e AA2050-T84, bem como entre as direções L-T e T-L para analisar o comportamento das ligas, quando submetidos à temperatura ambiente e criogênica. Para realizar a análise comparativa entre as ligas e entre as direções, foram utilizados corpos de prova tipo C(T) (Compacto Tension), pré-trincados em fadiga. A análise comportamental das ligas foram avaliadas através dos ensaios de tenacidade à fratura, KIC, Curva KR, fadiga, da/dN. A microestrutura foi caracterizada através da microscopia ótica, microscopia eletrônica de varredura e microscopia eletrônica de transmissão. Foi observado que na direção L-T há uma maior resistência à propagação da trinca em relação à direção T-L, no que diz respeito à Curva KR, tanto para temperatura ambiente quanto para temperatura criogênica. Quando comparou-se as duas ligas na direção L-T em temperatura ambiente, ambas apresentaram um fator de intensidade de tensão similar. Os resultados dos ensaios de fadiga mostraram que a direção T-L é mais sensível à razão de carga. Analisando os resultados entre as direções L-T e T-L, observou-se que as duas ligas apresentaram comportamento anisotrópico. / A comparative study was made of the AA7050-T7451 and AA2050-T84 alloys and of the L-T and T-L directions to analyze the behavior of the alloys when subjected to room and cryogenic temperatures. The comparative analyses of the alloys and directions were performed using fatigue-precracked compact tension (CT) test specimens. The behavior of the alloys was analyzed based on fracture toughness, KIC, KR curve, fatigue, and da/dN tests. Their microstructure was characterized by optical microscopy, scanning electron microscopy and transmission electron microscopy. The KR curve indicated that resistance to crack propagation was higher in the L-T direction than in the T-L direction at both room and cryogenic temperatures. In a comparison of the two alloys in the L-T direction at room temperature, they were found to present a similar stress intensity factor. The results of the fatigue tests demonstrated that the T-L direction is more sensitive to the load ratio. An analysis of the results in the L-T and T-L directions indicated that the two alloys exhibited anisotropic behavior.

No presente trabalho, foi desenvolvida uma metodologia sintética para a funcionalização de um monossacarídeo derivado da D-glicose através do Rearranjo de Ferrier, utilizando-se um sal de organotrifluoroborato de potássio como nucleófilo. Em seguida, foi feita a reação de cicloadição azida-acetileno com cobre, através de estratégias simples e eficientes, que seguem a filosofia da click chemistry, permitindo a preparação de uma série de compostos com grande diversidade estrutural, possuindo dois anéis heterocíclicos e diversos substituintes, com promissora atividade biológica. Dando continuidade ao projeto, foi feita a metanólise dos grupamentos acetila, com carbonato de potássio e metanol. Assim, as novas moléculas adquirem maior hidrofilicidade e podem ser enviadas para novos testes biológicos, para fins de comparação com as anteriores. A partir dos compostos desprotegidos, foi feita a mesilação seletiva da hidroxila primária do açúcar e a substituição com selenolato de sódio, com a obtenção de seleno-carboidratos inéditos. Em uma segunda etapa do trabalho, exploramos a reatividade do núcleo triazólico, com a reação de troca Te/Li seguida de captura por eletrófilo. O material de partida foi sintetizado a partir do fenil acetileno. Com o triazol telurado em mãos, partimos para as reações de troca e captura por eletrófilo. Utilizamos diferentes tipos de eletrófilos, como aldeídos, cetonas, iodetos, dentre outros. / We developed a synthetic methodology for the functionalization of a monosaccharide derived from D-glucose, using the Ferrier rearrangement with a potassium organotrifluoroborate salt as the nucleophile. This way, a series of coumpounds with high structural diversity and two heterocyclic rings having different substituents were produced, using the azide-acetylene cycloaddition reaction. Through this simple and efficient methodology, that follows the \"click chemistry\" philosophy, we could synthesize molecules with promising biological activity. Continuing the project, we performed the methanolysis of the acetyl groups, with potassium carbonate and methanol. Thus, the new molecules become more hydrophilic and could be sent to new biological tests, for a comparison with the previous ones. From the deprotected compounds, we were able to mesilate the primary hydroxyl and substitute it with sodium selenolate, obtaining novel selenium-carbohydrates. In a second part of our work, we were able to exploit the triazole reactivity trough the Te/Li exchange reaction followed by the electrophile capture. The starting material was obtained from phenyl acetylene. With the teluratte in our hands, we set out to the exchange reactions, using several types of electrophiles, such as aldehydes, ketones, iodide, among others.

A Função Resposta (FR) foi obtida para os detectores semicondutores Ge e Si(Li) usando o método semiempírico. A FR foi calculada para cinco detectores, 4 de HpGe, de volumes ativos 89 cm3, 50 cm3, 8 cm3 e 5 cm3, e um detector de Si(Li) de 0,143 cm3 de volume ativo. O intervalo de energia estudado dói de 6 keV até 1,5 MeV. Dois tipos de estudos foram realizados neste trabalho. O primeiro estudo foi a dependência da FR com a geometria de detecção. Este estudo envolveu o cálculo da FR para uma geometria denominada simples e a extrapolação da FR calculada. A extração da FR foi realizada para analisar tanto espectros obtidos com uma geometria com blindagem, como espectros onde a distância fonte-detector foi modificada. O segundo estudo foi a dependência da FR com a eletrônica de detecção. Este estudo foi realizado variando-se o tempo de formação de pulso na eletrônica de detecção. O objetivo foi a de verificar a existência ou ausência do efeito do déficit balístico na resolução do detector. Este efeito não foi observado. As componentes da FR que descrevem a região de absorção total da energia dos fótons incidentes, bem como as componentes que descrevem a absorção parcial dessa energia foram estudadas. Particularmente, neste trabalho, foram propostas funções empíricas tanto para o tratamento do espalhamento Compton múltiplo originado no próprio detector (cristal), como para o espalhamento de fótons originado nas vizinhanças do cristal. Um estudo através de simulações via Monte Carlo foi também realizado, para a compreensão das estruturas de espalhamento de fótons produzidas numa blindagem de ferro. Uma proposta de deconvolução de espectros envolvendo radiação espalhada foi estudada, para fins de cálculo da dose depositada no material espalhador. / The Response Function (RF) for Ge and Si(Li) semiconductor detectors was obtained. The RF was calculated for Five detectors, four HpGe with active volumes of 89 cm3, 50 cm3, 8 cm3 and 5 cm3, and one Si(Li) with 0,143 cm3 of active volume. The intervalo f energy studied ranger from 6 keV up to 1,5 MeV. Two kinds of studies were done in this work. The first one was the RF dependence with the detection geometry. Here the calculation of the RF for a geometry named as simple and na extrapolation of that RF, were both done. The extrapolation peocess analyzed both, spectra obtained with a shielding geometry and spectra where the source-detector distance was modified. The second one was the RF dependence with the detection electronics. The purpose was to verify the effect of the ballistic déficit in the resolution of the detector. This effect was not observed. The RF component that describe the region of the total absorption of the energy of the incident phtons, and the partial absorption of this energy, were both treated. In particular, empirical functions were proposed for the treatment of both, the multiple scattering originated in the detector (crystal), and the phton scattering originated in materials of the neighborhood of the crytal. Another study involving Monte Carlo simulations was also done in order to comprehend the photon scattering strutures produced in na iron shield. A deconvolution method is suggested, for spectra related to scattered radition in order to assess the dose delivered to the scattered.

Objetivo: Até 10% dos casos de câncer de mama estão associados com uma síndrome genética de predisposição ao câncer. A identificação de possíveis portadores dessas síndromes e o consequente encaminhamento para aconselhamento genético permitem a adoção de estratégias direcionadas de prevenção e rastreamento capazes de diminuir morbidade e mortalidade. O objetivo do presente estudo foi avaliar a proporção de pacientes com câncer de mama atendidos no Hospital Universitário de Santa Maria (HUSM) que necessitariam ser encaminhados para avaliação genética. Métodos: Pacientes com câncer de mama que iniciaram tratamento oncológico no HUSM durante o ano de 2014 foram considerados elegíveis. Uma entrevista foi conduzida com cada paciente para coleta de dados e exame físico dirigido. O questionário FSH-7 (Family Story Screening 7) e os critérios do NCCN (National Comprehensive Cancer Network) foram utilizados para identificar os pacientes que deveriam ser encaminhados para avaliação genética. Estes pacientes foram então avaliados quanto à indicação de teste genético - de acordo com as recomendações do NCCN para teste genético – e à probabilidade de mutações nos genes BRCA1 e BRCA2 através de modelos de predição de risco (BOADICEA, Penn II, sistema de escore de Manchester e tabelas da Myriad). Resultados: Dentre os 114 participantes do estudo, 65 (57%) preenchiam critérios de encaminhamento para avaliação genética de acordo com as diretrizes do NCCN. O questionário FHS-7 apresentou uma sensibilidade de 90% para identificar estes pacientes, com uma especificidade de 85%. A presença de história pessoal ou familiar de câncer de mama antes dos 50 anos foi o critério mais comum para indicar avaliação genética. Em relação aos testes genéticos, 52 pacientes (45%) deveriam ser testados para mutações nos genes BRCA1 e BRCA2 e 4 pacientes (3,5%) possuíam indicação de teste para mutações em TP53, de acordo com as recomendações do NCCN. Utilizando os modelos de predição de risco, 10,2% a 57,1% dos pacientes apresentavam uma probabilidade ≥ 10% de mutações em BRCA1 ou BRCA2. Conclusão: Este estudo revelou que a maioria dos pacientes com câncer de mama atendidos no HUSM possui indicação de encaminhamento para avaliação genética. A utilização de um questionário simples e rápido poderia identificar 90% destes pacientes. / Objective: Up to 10% of breast cancers are associated with a hereditary cancer syndrome. The identification of possible carriers of these syndromes and the subsequent referral for genetic counselling allow the adoption of tailored screening and prevention strategies capable of reducing morbidity and mortality. The aim of this study is to assess the proportion of patients with breast cancer treated at the University Hospital of Santa Maria (HUSM) that would need to be referred for genetic evaluation. Methods: Breast cancer patients who began cancer treatment at HUSM during the year 2014 were eligible. An interview was conducted with each patient for data collection and targeted physical examination. The FSH-7 (Family Story Screening 7) questionnaire and the NCCN (National Comprehensive Cancer Network) criteria were used to identify patients who should be referred for genetic evaluation. Then these patients were assessed for genetic testing criteria - according to the NCCN recommendations for genetic testing - and the likelihood of BRCA1 and BRCA2 mutations through risk prediction models (BOADICEA, Penn II, Manchester score system and Myriad tables). Results: Among the 114 study participants, 65 (57%) meet referral criteria for genetic evaluation according to the NCCN guidelines. The FHS-7 questionnaire showed a sensitivity of 90% to identify such patients with a specificity of 85%. The presence of personal or family history of breast cancer before age 50 was the most common criteria to indicate genetic evaluation. With respect to genetic testing, 52 patients (45%) should be tested for BRCA1 and BRCA2 mutations and 4 patients (3.5%) had test indication for TP53 mutations in accordance with the recommendations of the NCCN. Using risk prediction models, 10.2% to 57.1% of patients had a BRCA1 or BRCA2 mutations probability ≥ 10%. Conclusion: This study showed that most of the patients with breast cancer treated at HUSM have referral indication for genetic evaluation. The use of a fast and simple questionnaire could identify 90% of these patients.

Les pegmatites à éléments rares de type LCT sont depuis longtemps étudiées et exploitées pour leurs gemmes et les métaux rares qu’elles contiennent. Malgré de nombreuses études réalisées sur les processus d’enrichissement en éléments rares, ou les mécanismes à l’origine de leurs textures, très peu d’études ont été dédiées aux mécanismes de mise en place des pegmatites et à leur répartition spatiale à l’échelle du champ. Afin de déterminer les mécanismes moteurs à l’origine de l’ascension de ces magmas, une étude multidisciplinaire a été menée sur 3 champs de pegmatites à éléments rares, répartis à l’échelle de la chaîne Varisque. Les résultats démontrent la proximité entre la localisation des pegmatites minéralisées et l’intensité de la déformation encaissante. De plus, la mise en place de ces magmas semble facilitée par un certain mode de fracturation. La modélisation numérique de la mise en place des magmas dans ces zones crustales fragilisées indique que l’ascension est facilitée par leurs faibles viscosité et densité, mais aussi par des perméabilités crustales très élevées (> 10⁻¹² m²), à des profondeurs de l’ordre de 10 km. Enfin, d’après les signatures isotopiques du Li mesurées sur des micas pegmatitiques, le lithium ne fractionne pas depuis le granite voisin, jusqu’aux pegmatites les plus différenciées, puisque les valeurs δ⁷Li (‰) sont toutes comprises dans une gamme de - 2 à + 2 ‰, similaire à celle rencontrée dans les granites orogéniques. Nous suggérons donc que la genèse des magmas pegmatitiques est commune à celle des granites hyperalumineux. Les mécanismes de fracturation et d’attraction (« magma-pumping ») sont envisagés pour avoir favorisé l’ascension de ces magmas résiduels, enrichis en éléments rares, de faibles volumes, au cours de transitions brutales et de courtes durées (~ 10³ ans), de la perméabilité. L’ensemble de ces résultats permet de remettre en question le modèle du granite parent classiquement utilisé pour la prospection de ces gisements, et de proposer un modèle revisité couplant la genèse et la mise en place de ces magmas. / LCT-type rare-element pegmatites have long been studied and exploited for their gems and rare metals they contain. Despite many studies about the rare-element enrichment, or about the mechanisms leading their exotic textures, very few studies have been dedicated to the mechanisms controlling their emplacement and their spatial distribution at the scale of the pegmatite field. To better investigate the origin of ascent-driving mechanisms of these magmas, a multidisciplinary study was conducted on 3 rare-element pegmatite fields across the Variscan belt. The results demonstrate the spatial proximity of the rare-metals-rich pegmatites with the intensity of deformation of the hosting rocks. In addition, spatial statistical analyses suggest that the emplacement of such magmas has been facilitated by fracture-controlled model. According to numerical models, the rise of these pegmatite-forming melts along weakened crustal zones would be facilitated by their peculiar physico-chemical properties (low viscosity and density), but also by very high crustal permeability (> 10⁻¹² m²) at depths around 10 km. Finally, accordingly to Li isotope signatures measured on pegmatitic micas, lithium does not fractionate from neighbouring granite up to the more differentiated pegmatites, since all δ⁷Li (‰) fall within a range of - 2 to + 2 ‰, as for orogenic granites. Therefore, we suggest that the genesis these pegmatite-forming melts is common to that of peraluminous granites. Mechanisms of fracturation and magma-pumping may have favoured the rise of these low volumes of residual melts, enriched in rare-elements, during short periods (~ 10³ yrs) of strong permeability increase. These results question the granitic model commonly used for the exploration of this type of mineral deposits. We suggest a revisited model accounting for both genesis and emplacement controlling mechanisms of the pegmatite-forming melts.