La régénération et la réactivation des catalyseurs industriels d'hydrodésulfuration (HDS) CoMo/Al2O3 usés permettent leur réutilisation. Étant donné que ces catalyseurs sont considérés comme toxiques et polluants, la régénération/réactivation est une procédure intéressante dans un cadre écologique et économique. La régénération permet d'éliminer les dépôts de carbone mais ne permet pas de restaurer complètement l'activité des catalyseurs de HDS des nouvelles générations. En conséquence, une deuxième étape appelée « réjuvenation », impliquant l’ajout de composés organiques, a été mise en œuvre. L’étude de l’impact des additifs est d’un grand intérêt mais de nombreuses observations restent inexpliquées. En outre, certains brevets ont décrit une procédure de pré-activation permettant d'activer des catalyseurs ex situ afin d'éviter le contact avec des composés soufrés, ainsi que de manipuler et de charger en toute sécurité les catalyseurs dans des unités de HDS. De plus, il est de notoriété publique que la sulfuration est une étape critique ayant un impact important sur les performances catalytiques. En ce sens, cette étude vise à étudier l’effet de différentes conditions de rajeunissement, de pré-activation et de sulfuration ultérieure sur les caractéristiques finales des catalyseurs. Dans ce travail, trois catalyseurs régénérés et pré-activés ont été étudiés après différents protocoles de sulfuration. Les catalyseurs ont été testés et comparés dans la HDS de thiophène et SRGO. Aussi, l’influence des composés organiques ajoutés lors de la réjuvenation a été étudiée par différentes techniques (XPS, CO / IR, TEM…). Les résultats ont permis de déterminer les différences d'activité catalytique et d'établir une corrélation entre l'activité en HDS du thiophène et la concentration de sites CoMoS. Aucune divergence morphologique n'a été détectée dans les systèmes et les différences de performances catalytiques sont attribuées à un degré de promotion inégal. / Regeneration and reactivation of used industrial CoMo/Al2O3 hydrodesulfurization (HDS) catalysts allows reusing them. Since these catalysts are considered toxic and pollutant, regeneration/reactivation is an interesting procedure from an economical and ecological point of view. The regeneration allows removing carbon deposits but, by itself, does not restore completely the activity of new generations of HDS catalysts. Consequently, a second stage named rejuvenation, involving addition of organic compounds has been implemented. The study of the impact of additives is of great interest but many observations remain unexplained. Furthermore, some patents have described a pre-activation procedure that allows activating catalysts ex situ in order to avoid contact with sulfur compounds and a safe handling and loading of the catalysts in HDS units. In addition, it is common knowledge that sulfidation is a critical stage that impacts strongly the catalytic performance. In this sense, this study aims to study the effect of different rejuvenation, pre-activation and subsequent sulfidation conditions on final characteristics of catalysts. In this work three rejuvenated and pre-activated catalysts were studied after different sulfidation protocols. Catalysts were tested and compared in thiophene and SRGO HDS. Additionally, the influence of the organic compounds added during rejuvenation was studied by different techniques (XPS, CO/IR, TEM…). Results allowed determining differences in catalytic activity and establishing a correlation between thiophene HDS activity and CoMoS concentration. No morphological divergences were detected in the systems, instead, differences in catalytic performances are attributed to an unequal promotion degree

Made available in DSpace on 2014-06-11T19:22:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-06-28Bitstream added on 2014-06-13T20:09:55Z : No. of bitstreams: 1 jassi_fj_me_prud.pdf: 1543331 bytes, checksum: 8ed02d93a413e228c19bad39b3100681 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Contextualização: Observa-se na literatura que indivíduos assintomáticos podem não apresentar pré-ativação muscular de estabilizadores primários e não há estudos que apontem para os motivos da alteração no tempo de início de ativação muscular nessa população. Além disso, estudos preliminares em nosso laboratório mostraram que indivíduos assintomáticos apresentaram alterações em testes físicos e funcionais relacionados à capacidade de estabilização da região lombo-pélvica. Objetivo: Estudar o comportamento de pré-ativação dos músculos transverso do abdome/oblíquo interno (TrA/OI) e multífido lombar (ML), a capacidade de estabilização lombo-pélvica e a relação entre ambos. Metodologia: Foram selecionados 27 voluntários assintomáticos de ambos os sexos, com idades entre 20 e 28 anos (média = 23,85 ±2,21). Os voluntários foram submetidos a Testes Físicos Funcionais (TFF) para avaliar a capacidade de estabilização lombo-pélvica (Testes de Coordenação e Equilíbrio, Flexibilidade, Resistência e Comprimento e Força) e à Determinação de início de ativação muscular do TrA/OI e ML por meio da eletromiografia de superfície (EMG-S) durante movimento rápido de flexão do membro superior. Resultados: Embora a pré-ativação tenha sido o comportamento mais freqüente a ausência de pré-ativação do TrA/OI e ML ocorreu para alguns voluntários, sendo mais freqüente no músculo TrA/OI (26.6%) do gênero feminino. Nos TFF nenhum voluntário da amostra conseguiu obter valores de normalidade em todos os testes realizados e aqueles com maior número de voluntários com alteração foram: teste de flexibilidade do reto femoral e espinhais lombares, teste de enrolamento repetitivo do tronco, teste estático de resistência das costas de Sorensen e o teste de comprimento e força para o glúteo máximo. Entretanto, somente o teste de enrolamento... / Contextualization: It is observed in the literature that asymptomatic individuals may not have muscular pre-activation of primary stabilizers and there are no studies that point to the reasons for the change in time of onset of the muscle activation in this population. Furthermore, preliminary studies in our laboratory showed that asymptomatic individuals presented alterations in physical and functional tests with relationship the capacity of lumbo-pelvic stabilization. Objective: The study of pre-activation behavior of transversus abdominis/internal oblique muscle (TrA/OI) and lumborum multifidus (ML), the lumbo-pelvic stabilization capacity and the relationship of both. Methodology: Were selected 27 asymptomatic individuals of both sexes, with age between 20 e 28 years (mean = 23,85 ±2,21). The volunteers were submitted to a Physical Functional Tests (FFT) to evaluate a lumbo-pelvic stabilization capacity (coordination tests, balance, flexibility, endurance, length and force) and the determination of muscle activation onset of the TrA/OI and ML with superficial electromyography (EMG-S) during fast flexion arm movement. Results: Although pre-activation has been a usual result, the pre-activation absent of TrA/OI and ML happened in some volunteers, being more frequent for TrA/OI (26.6%) in the female gender. At TFF neither volunteers of the sample get regular scores in all tests executed. Those tests with more number of alterations were: rectus femoris and spinal lumbar flexibility, Sorensen static back endurance, and length and force to gluteus maximus. However, only repetitive trunk curl test showed great sensibility and specificity value with the primary stabilizers behavior of pre-activation

Há necessidade de esclarecimento sobre o efeito do método pré exaustão muscular na atividade eletromiográfica, visto que a literatura aponta resultados controversos sobre seu efeito no músculo específico. Em relação a instrução verbal, os estudos apontam resultados positivos em cargas até 60%1RM, mas há controvérsias a 80%1RM. O presente estudo verificou o efeito da instrução verbal em condições com e sem pré exaustão muscular sobre os domínios temporal e espectral do sinal eletromiográfico nas repetições iniciais, intermediárias e finais do exercício remada sentada. Foram coletados dados de 20 adultos jovens (19,80 ± 1,54 anos, 71,92 ± 9,39 kg e 177,28 ± 7,07 cm) com pouca (4,78 ± 1,30 meses) ou nenhuma experiência no treinamento de força. Todos estavam sem treinar há pelo menos 12 meses. Inicialmente houve o teste de quantificação de cargas, posteriormente nos testes 1 e 2, o sinal eletromiográfico foi registrado nos músculos: bíceps braquial, deltoide posterior, latíssimo do dorso e redondo maior. No Teste 1, uma série com e outra sem pré exaustão muscular foi realizada de forma randomizada com repetições máximas na intensidade de 70% de 1RM. O Teste 2 seguiu os mesmos procedimentos de coleta sendo acrescentada apenas a instrução verbal: \"Concentre-se em estender o ombro, puxe com as costas\". Os resultados apontaram que os voluntários aumentaram 7,44% (p = 0,049) a amplitude da atividade eletromiográfica do latíssimo do dorso nas repetições iniciais. Neste mesmo intervalo o redondo maior aumentou 15,63% (p = 0,020) na condição de instrução verbal com pré exaustão e os demais músculos não modificaram sua atividade. Nos intervalos intermediário e final os voluntários não alteraram a amplitude da atividade eletromiográfica com a instrução verbal em nenhum músculo analisado. Além disso, os voluntários não modificaram a frequência mediana do sinal em nenhum músculo durante toda série com instrução verbal. Em relação a pré exaustão, não houve alteração da amplitude da atividade eletromiográfica em nenhum músculo analisado. Os resultados mostram que a pré exaustão reduz 11,21% (p < 0,002) a frequência mediana no redondo maior e 8,58% (p < 0,002) no deltoide posterior no intervalo inicial. No intervalo intermediário esse padrão se repetiu, houveram reduções de 5,85% (p < 0,002) e 4,57% (p < 0,002) para os músculos redondo maior e deltoide posterior respectivamente. Os demais músculos não apresentaram modificações, assim como no intervalo final. Por fim os resultados mostraram que a pré exaustão muscular reduziu o número de repetições na remada sentada / There is a need for clarification on the effect of the pre-exhaustion method on electromyographic activity, since the literature points out controversial results on its effect on the specific muscle. Regarding verbal instruction, studies point to positive results in loads up to 60% 1RM, but there are controversies at 80% 1RM. The present study verified the effect of verbal instruction in conditions with and without muscular pre-exhaustion on the temporal and spectral domains of the electromyographic signal in the initial, intermediate and final repetitions of the seated row exercise. Data were collected from 20 young adults (19.80 ± 1.54 years, 71.92 ± 9.39 kg and 177.28 ± 7.07 cm) with little (4.78 ± 1.30 months) or no experience in strength training. Everyone was untrained for at least 12 months. Initially, there was the load quantification test, later in tests 1 and 2, the electromyographic signal was recorded in the muscles: biceps brachii, posterior deltoid, dorsal and major round. In Test 1, a series with and without muscle pre-exhaustion was performed in a randomized fashion with maximal repetitions at the intensity of 70% of 1RM. Test 2 followed the same collection procedures, adding only the verbal instruction: \"Focus on extending the shoulder, pull with the back\". The results showed that the volunteers increased 7.4% (p = 0.049) the amplitude of the electromyographic activity of the latissimus dorsi in the initial repetitions. In this same interval the teres major increased 15.63% (p = 0.020) in the verbal instruction condition with pre-exhaustion and the other muscles did not modify its activity. In the intermediate and final intervals, the volunteers did not alter the amplitude of the electromyographic activity with the verbal instruction in any muscle analyzed. In addition, volunteers did not modify the median frequency of the signal in any muscle during any verbal instruction series. Regarding pre-exhaustion, there was no change in amplitude of electromyographic activity in any muscle analyzed. The results show that the pre-exhaustion reduces the median frequency in the teres major 11.21% (p < 0.002) and 8.58% (p < 0.002) in the posterior deltoid in the initial interval. In the intermediate interval this pattern was repeated, there were reductions of 5.85% (p < 0.002) and 4.57% (p < 0.002) for the major round and posterior deltoid muscles respectively. The other muscles did not change, as did the final interval. Finally, the results showed that the pre muscular exhaustion reduced the number of repetitions in the seated row

Orientador: Rúben de Faria Negrão Filho / Banca: Carlos Marcelo Pastre / Banca: Amélia Pasqual Marques / Resumo: Contextualização: Observa-se na literatura que indivíduos assintomáticos podem não apresentar pré-ativação muscular de estabilizadores primários e não há estudos que apontem para os motivos da alteração no tempo de início de ativação muscular nessa população. Além disso, estudos preliminares em nosso laboratório mostraram que indivíduos assintomáticos apresentaram alterações em testes físicos e funcionais relacionados à capacidade de estabilização da região lombo-pélvica. Objetivo: Estudar o comportamento de pré-ativação dos músculos transverso do abdome/oblíquo interno (TrA/OI) e multífido lombar (ML), a capacidade de estabilização lombo-pélvica e a relação entre ambos. Metodologia: Foram selecionados 27 voluntários assintomáticos de ambos os sexos, com idades entre 20 e 28 anos (média = 23,85 ±2,21). Os voluntários foram submetidos a Testes Físicos Funcionais (TFF) para avaliar a capacidade de estabilização lombo-pélvica (Testes de Coordenação e Equilíbrio, Flexibilidade, Resistência e Comprimento e Força) e à Determinação de início de ativação muscular do TrA/OI e ML por meio da eletromiografia de superfície (EMG-S) durante movimento rápido de flexão do membro superior. Resultados: Embora a pré-ativação tenha sido o comportamento mais freqüente a ausência de pré-ativação do TrA/OI e ML ocorreu para alguns voluntários, sendo mais freqüente no músculo TrA/OI (26.6%) do gênero feminino. Nos TFF nenhum voluntário da amostra conseguiu obter valores de normalidade em todos os testes realizados e aqueles com maior número de voluntários com alteração foram: teste de flexibilidade do reto femoral e espinhais lombares, teste de enrolamento repetitivo do tronco, teste estático de resistência das costas de Sorensen e o teste de comprimento e força para o glúteo máximo. Entretanto, somente o teste de enrolamento... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Contextualization: It is observed in the literature that asymptomatic individuals may not have muscular pre-activation of primary stabilizers and there are no studies that point to the reasons for the change in time of onset of the muscle activation in this population. Furthermore, preliminary studies in our laboratory showed that asymptomatic individuals presented alterations in physical and functional tests with relationship the capacity of lumbo-pelvic stabilization. Objective: The study of pre-activation behavior of transversus abdominis/internal oblique muscle (TrA/OI) and lumborum multifidus (ML), the lumbo-pelvic stabilization capacity and the relationship of both. Methodology: Were selected 27 asymptomatic individuals of both sexes, with age between 20 e 28 years (mean = 23,85 ±2,21). The volunteers were submitted to a Physical Functional Tests (FFT) to evaluate a lumbo-pelvic stabilization capacity (coordination tests, balance, flexibility, endurance, length and force) and the determination of muscle activation onset of the TrA/OI and ML with superficial electromyography (EMG-S) during fast flexion arm movement. Results: Although pre-activation has been a usual result, the pre-activation absent of TrA/OI and ML happened in some volunteers, being more frequent for TrA/OI (26.6%) in the female gender. At TFF neither volunteers of the sample get regular scores in all tests executed. Those tests with more number of alterations were: rectus femoris and spinal lumbar flexibility, Sorensen static back endurance, and length and force to gluteus maximus. However, only repetitive trunk curl test showed great sensibility and specificity value with the primary stabilizers behavior of pre-activation / Mestre

This work focuses on understanding the impact-initiated combustion of aluminum powder compacts. Aluminum is typically one of the components of intermetallic-forming structural energetic materials (SEMs), which have the desirable combination of rapid release of thermal energy and high yield strength. Aluminum powders of various sizes and different levels of mechanical pre-activation are investigated to determine their reactivity under uniaxial stress rod-on-anvil impact conditions, using a 7.62 mm gas gun. The compacts reveal light emission due to combustion upon impact at velocities greater than 170 m/s. Particle size and mechanical pre-activation influence the initiation of aluminum combustion reaction through particle-level processes such as localized friction, strain, and heating, as well as continuum-scale effects controlling the amount of energy required for compaction and deformation of the powder compact during uniaxial stress loading. Compacts composed of larger diameter aluminum particles (~70µm) are more sensitive to impact initiated combustion than those composed of smaller diameter particles. Additionally, mechanical pre-activation by high energy ball milling (HEBM) increases the propensity for reaction initiation. Direct imaging using high-speed framing and IR cameras reveals light emission and temperature rise during the compaction and deformation processes. Correlations of these images to meso-scale CTH simulations reveal that initiation of combustion reactions in aluminum powder compacts is closely tied to mesoscale processes, such as particle-particle interactions, pore collapse, and particle-level deformation. These particle level processes cannot be measured directly because traditional pressure and velocity sensors provide spatially averaged responses. In order to address this issue, quantum dots (QDs) are investigated as possible meso-scale pressure sensors for probing the shock response of heterogeneous materials directly. Impact experiments were conducted on a QD-polymer film using a laser driven flyer setup at the University of Illinois Urbana-Champaign (UIUC). Time-resolved spectroscopy was used to monitor the energy shift and intensity loss as a function of pressure over nanosecond time scales. Shock compression of a QD-PVA film results in an upward shift in energy (or a blueshift in the emission spectra) and a decrease in emission intensity. The magnitude of the shift in energy and the drop in intensity are a function of the shock pressure and can be used to track the particle scale differences in the shock pressure. The encouraging results illustrate the possible use of quantum dots as mesoscale diagnostics to probe the mechanisms involved in the impact initiation of combustion or intermetallic reactions.

<p>Förmågan att prestera under akut eller kraftig stress är en förutsättning för en del yrken. Forskningsresultaten gällande hur stress påverkar prestation pekar åt olika håll. Denna studie undersökte sambandet mellan fysiologisk arousal och kognitiv problemlösningsförmåga under stress. Trettiotvå polisstudenter testades på Ravens test av flytande intelligens APM set II både före och efter att antingen ha sprungit i tjugo minuter eller haft en självskyddslektion på ca fyrtio minuter. Resultaten från en mixed ANOVA för beroende mätningar visade på en signifikant interaktionseffekt (F (30) = 6,547, p < 0,05) – en ökning i prestationen hos självskyddsgruppen med arton procent och en minskning med femton procent hos löpningsgruppen. En möjlig förklaring till skillnaden i prestation kan vara att självskyddsträningen ger upphov till en annorlunda mental och kognitiv aktivering än löpningen. Graden av arousal kunde vidare inte förklara skillnaderna mellan grupperna och begreppets användbarhet i detta sammanhang kan kanske ifrågasättas.</p>

Förmågan att prestera under akut eller kraftig stress är en förutsättning för en del yrken. Forskningsresultaten gällande hur stress påverkar prestation pekar åt olika håll. Denna studie undersökte sambandet mellan fysiologisk arousal och kognitiv problemlösningsförmåga under stress. Trettiotvå polisstudenter testades på Ravens test av flytande intelligens APM set II både före och efter att antingen ha sprungit i tjugo minuter eller haft en självskyddslektion på ca fyrtio minuter. Resultaten från en mixed ANOVA för beroende mätningar visade på en signifikant interaktionseffekt (F (30) = 6,547, p &lt; 0,05) – en ökning i prestationen hos självskyddsgruppen med arton procent och en minskning med femton procent hos löpningsgruppen. En möjlig förklaring till skillnaden i prestation kan vara att självskyddsträningen ger upphov till en annorlunda mental och kognitiv aktivering än löpningen. Graden av arousal kunde vidare inte förklara skillnaderna mellan grupperna och begreppets användbarhet i detta sammanhang kan kanske ifrågasättas.