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Influence of the Dehydrogenation Function on Propene Aromatization Catalysis Over Physical Mixtures of PtZn/SiO2 and H-MFIArunima Saxena (10579292) 20 April 2022 (has links)
<p>This work studies propene aromatization reaction on H-MFI (Si/Al = 40) and physical mixtures of H-MFI (Si/Al = 40) and PtZn/SiO2 (2 wt% Pt, 3 wt% Zn) at 723 K - 823 K and 3 kPa C3H6. The influence of PtZn alloy (dehydrogenation function) is investigated on the product distribution and selectivity of metal-acid catalyzed propene aromatization. Typical product distribution consists of methane, ethane, ethene, propane, C4-C6 alkanes and alkenes, and benzene, toluene, xylene (BTX). On comparing the BTX carbon selectivity over the two catalysts at first equivalent space velocity and then equivalent propene conversion, higher BTX selectivities are observed on PtZn+H-MFI than H-MFI in both the cases. The higher BTX selectivities were previously attributed in the literature to the dehydrogenation pathway on the metal function. However, space velocity is an inadequate descriptor of reaction progress because the conversion of reactants can be different at same space velocity. Similarly, propene conversion is an incomplete descriptor for reaction progress because intermediates such as ethene and C4-C6 hydrocarbons react to form higher molecular weight hydrocarbons and subsequent aromatics as the reaction progresses. Such reactive hydrocarbons were lumped together as reactive intermediates and the remaining hydrocarbons were classified as non-reactive species or products. When BTX selectivities over PtZn-H-MFI and H-MFI are compared at equivalent temperature and equivalent conversion of all the reactive intermediates, both the catalysts exhibit similar BTX selectivities, suggesting that the presence of the dehydrogenation metal function doesn’t influence the selectivity towards BTX products. Further, we hypothesize cyclohexene as an intermediate in aromatic formation and use cyclohexene conversion as a probe reaction to understand how aromatics are formed over Brønsted acid sites and PtZn alloy. Cyclohexene conversion results at 723 K and 823 K shows the presence of an alternate route of aromatic formation via dehydrogenation of cycloalkenes, and this dehydrogenation pathway has an order of magnitude higher rates than the hydride transfer route on Brønsted acid sites. Further, we propose dominant reaction pathways of C1 – BTX hydrocarbon formation on H-MFI and bifunctional PtZn+H-MFI. Finally, we discuss the implications of using PtZn+H-MFI on developing a commercial propylene aromatization process and provide our recommendations for chemical and fuel production. In summary, these findings reveal previously unknown mechanistic details of metal bifunctionality for propene aromatization catalysis. </p>
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Hälsorelaterad livskvalitet och fatigue hos patienter med hjärtinfarkt utan kranskärlsförträngningar : en enkätstudieBerg, Emma, Schweitz, Carl January 2018 (has links)
SAMMANFATTNING MINOCA (Myocardial Infarction with Non Obstructive Coronary Arteries) är ett begrepp som beskriver en grupp av patienter som initialt uppvisar hjärtinfarktliknande symptom, men där patienternas kranskärl sedan visar sig vara normala. Det finns olika bakomliggande orsaker till detta tillstånd. I begreppet MINOCA ingår bland annat hjärtinfarkt, takotsubokardiomyopati och myokardit. Hos en del av patienterna förblir orsaken till sjukdomen oklar. Patienternas livskvalitet påverkas och fatigue kan ha en negativ inverkan på återhämtningen. Fatigue kan leda till en avsaknad av energi till att hantera vardagslivet, vilket kan påverka patienternas motivation till att orka genomföra olika sysslor och ge en sämre livskvalitet. Syftet med studien var att undersöka självskattad hälsorelaterad livskvalitet och fatigue hos patienter med hjärtinfarkt utan kranskärlsförträngningar vid insjuknandet och sex månader efter insjuknandet. Metoden för studien var kvantitativ, med en deduktiv ansats och en prospektiv icke-experimentell design. Datamaterialet hämtades från den pågående SMINC-2 studien. Till studien inkluderades 101 patienter genom ett bekvämlighetsurval, 74 kvinnor och 27 män. Datainsamlingen genomfördes med hjälp av enkäterna RAND-36, som mäter hälsorelaterad livskvalitet och MFI-20 (Multidimensional Fatigue Inventory). Dataanalysen genomfördes med hjälp av statistikprogrammet SPSS Statistics, version 23. Resultatet av mätningen med RAND-36 visade att det fanns en signifikant förbättring hos patienterna med MINOCA inom dimensionerna vitalitet/fatigue, social funktion, rollfunktion-emotionella orsaker och psykiskt välbefinnande sex månader efter insjuknandet. Inom de olika diagnosgrupperna så uppnådde patienterna med myokardit en signifikant förbättring i dimensionen vitalitet/fatigue. Patienterna med takotsubo uppnådde en signifikant förbättring inom dimensionerna vitalitet/fatigue, social funktion och psykiskt välbefinnande. Resultatet av MFI-20 visade att den sammansatta poängen för alla patienter med MINOCA hade förbättrats signifikant efter sex månader. De dimensioner där patienterna uppnådde en signifikant förbättring efter sex månader var generell fatigue och mental fatigue. Patienterna med osäker diagnos var den enda diagnosgruppen som uppnådde en signifikant förbättring och dimensionerna var mental fatigue och generell fatigue. Slutsatsen är att patienterna med MINOCA upplevde en försämrad generell hälsorelaterad livskvalitet och en ökad känsla av fatigue vid insjuknandet. Den samlade upplevelsen av livskvalitet och fatigue hade förbättrats sex månader efter insjuknandet, men var fortfarande negativt påverkad. Patienter med diagnosen takotsubo och de med osäker diagnos uppvisade en sämre livskvalitet och en ökad känsla av fatigue inom flest dimensioner, jämfört med patienterna med myokardit och de med hjärtinfarkt.
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STRUCTRUE PROPERTY RELATIONSHIPS IN VARIOUS FILLED POLYMERSYu, Jiong 21 January 2005 (has links)
No description available.
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Captage du CO2 par procédé membranaire : application au transport routier / High-flux MFI-alumina hollow fibres : a membrane-based process for on-board CO2 capture from internal combustion vehiclesNicolas, Charles-Henri 18 October 2011 (has links)
Ces travaux portent sur la conception et le développement d’un procédé membranaire de captage/stockage du CO2 embarqué pour le transport routier. Dans une première partie, nous réalisons la simulation d’un procédé membranaire embarqué de captage du CO2 dans le cas d’un poids lourd (>3500 kg). Ceci comprend l’analyse énergétique de la séparation et de la compression des gaz, l’évaluation des surfaces et volumes requis ainsi que l’autonomie de l’unité de stockage et la surconsommation engendrée par ce dispositif. Nous étudions dans un second temps la relation entre qualité des supports fibres creuses et celle des membranes nanocomposites MFI-alumine synthétisées. Nous nous intéressons ensuite aux performances des membranes nanocomposites dans la séparation CO2/N2 en phase gazeuse. Plus particulièrement nous évaluons l’influence de la substitution isomorphique du silicium par le bore et le germanium, ainsi que l’échange du proton de valence par d’autres atomes, sur la séparation en question. Un chapitre est dédié à l’évaluation des paramètres thermodynamiques (adsorption) et cinétiques (diffusion) de la séparation CO2/N2. Enfin, nous analysons l’influence de la présence de polluants dans le mélange à séparer (eau, NOx, hydrocarbures) sur les performances séparatives des membranes synthétisées. / This work focuses on the conception and development of a membrane-based process for an on-board CO2 capture/storage application. In a first part, we simulate an on-board CO2 capture unit based on a membrane process for the case study of a heavy vehicle (>3500 kg). This study includes an energy analysis of the impact of gas separation and compression on the required membrane surface and module volume, as well the autonomy of the storage unit and the energy overconsumption involved in the process. In a second part, we study the influence of the hollow-fibre support quality on the final intergrowth level of nanocomposite MFI-alumina membranes. Special attention is devoted to the influence of the isomorphic substitution of silica by boron and germanium, and replacement of the counter-cation (proton) by other elements, on the CO2/N2 separation and permeance properties. Next, a complete chapter has been devoted to the evaluation of the thermodynamic (adsorption) and kinetic (diffusion) parameters in the CO2/N2 separation. Finally, we analyze the influence of standard pollutants (water, NOx, hydrocarbons) on the CO2 separation properties of the synthesized membranes.
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L’inflammation chronique à bas bruit et ses relations avec la fatigue et les altérations cognitives chez les patients souffrant de troubles métaboliques / Relationship of chronic low-grade inflammation with fatigue and cognitive alterations in patients suffering from metabolic disordersLasselin, Julie 12 December 2012 (has links)
Les cytokines, produites lors de l’activation du système immunitaire, ont la capacité d’agir au niveau du système nerveux central et d’induire diverses altérations comportementales. Lorsque l’activation du système de l’immunité innée devient chronique, ces altérations comportementales peuvent évoluer en véritables symptômes neuropsychiatriques. La physiopathologie des symptômes neuropsychiatriques qui se développent dans un contexte d’inflammation chronique à bas bruit, c’est-à-dire caractérisé par une activation chronique des processus immunitaires mais à un niveau relativement faible, est peu connue et reste à déterminer. L’implication de l’inflammation chronique à bas bruit dans les symptômes de fatigue et les altérations cognitives constitue l’élément d’étude principal de ce travail de thèse. Les troubles métaboliques, tels que l’obésité et le diabète de type 2, sont de bons modèles pour une telle étude. Ces deux pathologies sont en effet caractérisées par une inflammation chronique à bas bruit qui proviendrait, au moins en partie, du tissu adipeux. De plus, la fatigue et les altérations cognitives sont fréquentes chez les patients souffrant de troubles métaboliques. Compte tenu du rôle connu de l’inflammation dans la physiopathologie de ces altérations comportementales, leur développement dans des contextes de troubles métaboliques pourrait également être lié à l’activation chronique à bas bruit de processus inflammatoires. Différents objectifs ont été définis pour tester cette hypothèse : 1) caractériser et spécifier les symptômes de fatigue et les altérations cognitives chez des patients diabétiques ou obèses ; 2) évaluer la relation entre inflammation systémique et état inflammatoire du tissu adipeux ; 3) étudier l’association de l’inflammation chronique à bas bruit avec les symptômes de fatigue et les altérations cognitives des patients souffrant de troubles métaboliques. Nos résultats indiquent que la fatigue, en particulier la fatigue générale et physique, représente une caractéristique fondamentale des troubles métaboliques. Des perturbations cognitives, se traduisant par un ralentissement psychomoteur dans un test de temps de réaction ainsi qu’une altération de performance dans une tâche de planification spatiale, ont également été décelées chez les patients diabétiques de type 2, particulièrement ceux sous insulinothérapie, et chez les patients obèses. Des altérations mineures étaient également mesurées dans une tâche d’empan spatial rétrograde chez les patients obèses. En ce qui concerne les données biologiques, nos résultats indiquent diverses associations entre l’inflammation systémique et l’expression des marqueurs inflammatoires (cytokines inflammatoires, dont le MCP1, et marqueurs des cellules T) dans le tissu adipeux viscéral des patients obèses. De façon intéressante, l’inflammation systémique à bas bruit était associée aux dimensions de fatigue (générale, mentale, réduction des activités et de la motivation) et aux altérations de performance dans les tests ciblant les fonctions exécutives. Dans l’ensemble, ces résultats supportent l’hypothèse de l’implication des macrophages et des lymphocytes T du tissu adipeux dans l’état inflammatoire systémique associé à l’obésité. Il suggère en outre que l’inflammation systémique à bas bruit pourrait participer au développement de la fatigue et des altérations cognitives chez les patients souffrant de troubles métaboliques. Ce travail de thèse offre une caractérisation précise des symptômes de fatigue et des altérations cognitives associées aux troubles métaboliques. En outre, ce travail apporte d’importantes informations sur les relations de l’inflammation chronique à bas bruit avec ces symptômes, et permet d’affiner les hypothèses relatives à l’implication de processus inflammatoires dans la physiopathologie de ces altérations. / Cytokines produced during the activation of the immune system have the ability to act within the central nervous system and to induce a large number of behavioral alterations. When the activation of immune system becomes chronic and unregulated, these behavioral alterations may lead to the development of neuropsychiatric symptoms. The pathophysiology of neuropsychiatric symptoms that develop in conditions of chronic low-grade inflammation context (i.e., characterized by a chronic but low activation of inflammatory processes), remains unknown. The main aim of this thesis was to investigate the involvement of low-grade inflammation in the development of fatigue symptoms and cognitive alterations in patients with metabolic disorders including obesity and type 2 diabetes. These conditions are characterized by a chronic low-grade inflammatory state, manifesting by higher blood concentrations of inflammatory factors. This inflammatory state would originate, at least partially, from the adipose tissue. Moreover, fatigue symptoms and cognitive alterations are common in metabolic disorders. Given the role of inflammation in the physiopathology of these symptoms, their development could also rely on chronic low-grade inflammatory processes. Several objectives were defined to test this hypothesis: 1) to characterize fatigue symptoms and cognitive alterations in obese and diabetic patients; 2) to assess the relationship of systemic inflammation with the inflammatory state of the adipose tissue; and 3) to investigate the association of low-grade inflammation with fatigue symptoms and cognitive alterations in patients with metabolic disorders. Fatigue symptoms and cognitive function were respectively assessed using the multidimensional fatigue inventory (MFI) and the neuropsychological tests automated battery CANTAB in diabetic patients (type 1 and type 2) and in obese patients before and after bariatric surgery. A control group was included for each model (obesity and type 2 diabetes). Circulating concentrations of inflammatory markers, as well as expression of inflammatory markers in the visceral adipose tissue of obese patients, were measured. Our results indicate that fatigue symptoms, especially in the dimensions of general and physical fatigue, represent fundamental characteristics of patients suffering from metabolic disorders. In addition, cognitive alterations (psychomotor slowing and alterations in spatial planning performance) were measured in type 2 diabetic patients, more particularly those under insulin treatment, and in obese patients. Slight alterations in the test of backward spatial span were measured in obese patients. With respect to biological data, our results indicate significant relationships between systemic inflammation and inflammatory markers (inflammatory cytokines, including MCP1, and T-cell markers) in the visceral adipose tissue of obese patients. Interestingly, chronic low-grade inflammation was associated with fatigue symptoms (general fatigue, mental fatigue, reduced activity and motivation) and performance alterations in tests assessing executive functions. Altogether, these data support the hypothesis of the involvement of the adipose macrophages and T lymphocytes in the systemic inflammatory state associated with obesity. Moreover, these results suggest that systemic low-grade inflammation associated with metabolic disorders may contribute to the physiopathology of fatigue and cognitive alterations in these conditions. In conclusion, these studies provide a precise characterization of fatigue symptoms and cognitive alterations associated with metabolic disorders, such as obesity or type 2 diabetes. In addition, this thesis work gives interesting information about the relationships of chronic low-grade inflammation and fatigue and cognitive symptoms, and refines hypotheses regarding the involvement of inflammatory processes in the physiopathology of these symptoms in patients with diabetes or obesity.
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Studium chování betonu při působení vysokých teplot / Behavior of concrete at high temperaturesDvořáková, Michaela January 2014 (has links)
The aim of this diploma thesis is to focus on the resistance of concrete exposed to high temperatures especially with focus of resistance against explosive spalling as well as clarifying the mode of action of various types of polypropylene fibres. The theoretical part is an introduction to the issues of explosive spalling, its mechanisms and majority influencing factors. Further description of the processes taking place in the structure of concrete under extreme thermal load, distribution and size of pores in concrete, thermal load, temperature-time curves and their applications, methods of elimination of negative behaviour of concrete exposed to thermal loading (passive and active methods), mode of action of polypropylene fibres and more is also included in the theoretical part. The main aim of experimental part is to verify the function of polypropylene fibers of various Melt Flow Indexes (MFI) and dosage. Primarily, the test samples with content of the PP-fibers are compared to the reference sample without fibers. Secondarily, the samples with standard PP-fibers (with MFI 25) with dosage 2.0 kg/m3 are compared to samples with modified PP-fiber (with MFI 2500) of dosage 0.9 kg/m3. Photogrammetric images were used for evaluation and comparison of spalled surfaces and its depth. Determination of the softening temperature and melting point of the modified and standard PP-fibers was made by using a high temperature microscope video. The second part of the experimental work was to define concrete permeability at different temperatures and pressures. Permeability was measured at temperatures of 20°C, 90°C, 150°C, 175°C, 200°C, 225°C and 250°C and at pressure of 0.2, 0.4 and 0.6 MPa.
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Synthesis Of Zeolite Membranes In Flow SystemOnder, Aylin 01 October 2012 (has links) (PDF)
Zeolite membranes are formed as a thin zeolitic layer on the supports. They are usually synthesized by hydrothermal methods in batch systems. In this study, MFI and SAPO-34 type zeolite membranes were produced on macroporous tubular alumina supports in a recirculating flow system at elevated temperatures for the first time in the literature. During the synthesis, the synthesis mixture is flown between the reservoir and the membrane module which includes the support material.
The synthesis temperatures were 180° / C and 220° / C, and the corresponding system pressures were approximately 20 and 30 bars for MFI and SAPO-34, respectively. The CH4 and n-C4H10 single gas permeances were measured through MFI membranes and the performance of membranes was investigated in the separation of equimolar CH4/n-C4H10 mixtures. The best MFI membrane had a CH4 single gas permeance of 1.45x10-6 mol/m2-s-Pa and CH4/n-C4H10 ideal selectivity of 35 at 25oC. The membranes preferentially permeated n-C4H10 in the separation of mixtures. The n-C4H10/CH4 separation selectivity was 43.6 with a total permeance of approximately 0.8x10-6 mol/m2-s-Pa at 25oC.
The ideal selectivities of CO2/CH4 of SAPO-34 membrane synthesized in stagnant medium were 227, and > / 1000 at 220 and 200oC, respectively. Formation of amorphous structure and the additional secondary phases (impurities) were observed on SAPO-34 membranes synthesized in recirculating flow system. The results showed that it is possible to produce SAPO-34 and high quality MFI membranes by a recirculating flow system operating at elevated temperature.
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Assessment of fatigue in patients with COPD participating in a pulmonary rehabilitation program : a feasibility studyWong, Cindy Jennifer 15 April 2009
Fatigue is a distressing, complex, and multidimensional sensation, that is common in individuals with chronic obstructive pulmonary disease (COPD), and impacts negatively on their functioning and quality of life. Limited research has been conducted to examine how various factors may influence the different dimensions of subjective fatigue experienced in these individuals. Four dimensions of subjective fatigue including: emotional, behavioural, cognitive, and physical, were examined in a convenience sample of 42 participants with COPD who attended an outpatient pulmonary rehabilitation program. The primary purpose of this feasibility study was to determine the proportion of individuals experiencing the four dimensions of fatigue, and to examine the relationships between these dimensions of fatigue and various influencing factors (dyspnea, depression, anxiety, sleep quality, activity limitation, heart rate, and oxygen saturation). The secondary purpose was to compare the four dimensions of fatigue by sex, supplemental oxygen use, smoking status, and severity of dyspnea, and to examine the relationships between the four dimensions of fatigue and age, the number of co-morbidities, and the amount of pulmonary rehabilitation received. Self-report questionnaires were used to measure fatigue (Multidimensional Fatigue Inventory MFI), anxiety and depression (Hospital Anxiety and Depression Scale HADS), and sleep quality (Pittsburgh Sleep Quality Index PSQI). Pulmonary rehabilitation health records were accessed to collect data on the remaining variables. The majority of the participants (61.9% - 81.0%) experienced moderate levels of subjective fatigue in all four dimensions. Moderate to severe levels of physical fatigue were experienced in 95.3% of the participants. The only significant relationship was between anxiety and emotional fatigue; all other relationships were statistically insignificant. There were no significant differences between sex, supplemental oxygen use, smoking status, and severity of dyspnea on the four dimensions of subjective fatigue. Many of the participants had probable presence of clinical anxiety (42.9%), where the prevalence of anxiety was nearly twice as high as depression (21.4%). Findings from this study can be used by healthcare professionals to gain a better understanding of fatigue in individuals with COPD who attend pulmonary rehabilitation, and help in developing effective interventions for reducing the distressing effects of fatigue.
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Assessment of fatigue in patients with COPD participating in a pulmonary rehabilitation program : a feasibility studyWong, Cindy Jennifer 15 April 2009 (has links)
Fatigue is a distressing, complex, and multidimensional sensation, that is common in individuals with chronic obstructive pulmonary disease (COPD), and impacts negatively on their functioning and quality of life. Limited research has been conducted to examine how various factors may influence the different dimensions of subjective fatigue experienced in these individuals. Four dimensions of subjective fatigue including: emotional, behavioural, cognitive, and physical, were examined in a convenience sample of 42 participants with COPD who attended an outpatient pulmonary rehabilitation program. The primary purpose of this feasibility study was to determine the proportion of individuals experiencing the four dimensions of fatigue, and to examine the relationships between these dimensions of fatigue and various influencing factors (dyspnea, depression, anxiety, sleep quality, activity limitation, heart rate, and oxygen saturation). The secondary purpose was to compare the four dimensions of fatigue by sex, supplemental oxygen use, smoking status, and severity of dyspnea, and to examine the relationships between the four dimensions of fatigue and age, the number of co-morbidities, and the amount of pulmonary rehabilitation received. Self-report questionnaires were used to measure fatigue (Multidimensional Fatigue Inventory MFI), anxiety and depression (Hospital Anxiety and Depression Scale HADS), and sleep quality (Pittsburgh Sleep Quality Index PSQI). Pulmonary rehabilitation health records were accessed to collect data on the remaining variables. The majority of the participants (61.9% - 81.0%) experienced moderate levels of subjective fatigue in all four dimensions. Moderate to severe levels of physical fatigue were experienced in 95.3% of the participants. The only significant relationship was between anxiety and emotional fatigue; all other relationships were statistically insignificant. There were no significant differences between sex, supplemental oxygen use, smoking status, and severity of dyspnea on the four dimensions of subjective fatigue. Many of the participants had probable presence of clinical anxiety (42.9%), where the prevalence of anxiety was nearly twice as high as depression (21.4%). Findings from this study can be used by healthcare professionals to gain a better understanding of fatigue in individuals with COPD who attend pulmonary rehabilitation, and help in developing effective interventions for reducing the distressing effects of fatigue.
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Etude des interactions de molécules hôtes dans des zéolithes synthétiques par diffraction des rayons X à haute résolutionAubert, Emmanuel 13 November 2003 (has links) (PDF)
Les zéolithes sont des solides cristallins caractérisés par l'existence de canaux pouvant accueillir des ions et molécules hôtes. Ces matériaux sont donc utilisés dans de nombreux procédés physico-chimiques, tels que la séparation moléculaire, la catalyse, l'échange cationique, et plus récemment comme constituant de nouveaux matériaux composites. Dans ce travail nous nous sommes intéressés à la caractérisation des interactions dans les tamis moléculaires de type MFI, AFI et AlPO4-15 via la diffraction des rayons X à haute résolution sur monocristal et la thermogravimétrie et calorimétrie.<br /> Les monocristaux nécessaires ont été obtenus au laboratoire par synthèse hydrothermale. L'étude de la densité de charge de AlPO4-15 a révélé les interactions hôte / invité dans ce composé et, avec l'analyse de sa topologie, a permis d'en modéliser le potentiel électrostatique. L'étude de la zéolithe MFI a permis de localiser l'ion fluorure qui se trouve être lié à un atome de silicium de la charpente.
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