251 research outputs found
Distributed secondary gas injection via a fractal injector: A nature-inspired approach to improving conversion in fluidized bed reactors
No full textThe conversion in bubbling fluidized bed reactors is suppressed because the interphase mass transfer and gas-solid contact in bubbling fluidized bed reactors are often poor. Most of the gas is present in the form of bubbles, which have low surface-to-volume ratios and are nearly devoid of catalyst particles. The chaotic behaviour of the bubbles is difficult to predict and can change with reactor size, making scale-up very difficult. The work in this thesis presents a novel approach to overcoming these difficulties in bubbling fluidized beds. Nature uses branching, fractal structures, which greatly facilitate mass transfer in natural systems, such as trees and lungs. These structures scale easily, which is a very important feature as the organism grows. This approach can also be applied to fluidized beds. A fractal injector was developed for both quasi 2-D and 3-D beds to distribute a portion of the total gas flow throughout the fluidized bed. To determine the effect of this distributed secondary gas injection on the properties of a gas-solid fluidized bed, the study is split into four topics: the effect on the hydrodynamics of the fluidized bed, the mechanisms leading to the observed changes in the hydrodynamics, the residence time and macroscopic mixing of the gas, and the influence on the performance of the reactor. The results indicate that secondary gas injection via a fractal injector effectively reduces the bubble diameter by up to 30% (~70% reduction in the volume) and increases the gas-solid contact. It is shown that these effects lead to a higher conversion and selectivity in a bubbling fluidized bed reactor. Mechanisms for these effects are proposed.Applied Science
Fondaparinux and its derivatives
No full textFondaparinux is a pentasaccharide and consists of the five saccharides by which heparin and low-molecular weight heparins bind to and potentiate antithrombin. It is used as an alternative to low-molecular weight heparin in patients with acute coronary syndromes without persistent ST-segment elevation, and in patients with acute coronary syndromes with persistent ST-segment elevation who do not undergo reperfusion therapy or fibrinolytic therapy. For this indication, fondaparinux reduced the risk of major bleeding by 30% and the risk of death by 10% without an excess in thrombotic complications. Other approved indications are treatment of superficial vein thrombosis and prevention of venous thromboembolism after hip or knee arthroplasty, after abdominal surgery, and in acutely ill medical patients. Furthermore, fondaparinux is approved for the initial therapy in acute venous thromboembolism, although it is rarely used for this indication. Finally, fondaparinux is pathophysiologically attractive for the treatment of patients with heparin-induced thrombocytopenia and case series confirm its efficacy and safety although regulatory approval was never sought. Idraparinux and idrabiotaparinux are pentasaccharides with longer elimination half-lives than fondaparinux, allowing once-weekly dosing. Development of these drugs was halted because of an excess of bleeding (idraparinux) and commercial reasons (idrabiotaparinux).</p
Thrombosis and anticoagulant treatment in special populations
No full textIn this thesis, we evaluate the burden of venous thromboembolism and bleeding, as well as the efficacy and safety of anticoagulation and anticoagulation reversal strategies in subgroups of rare subjects. These include: healthy subjects treated with direct oral factor-Xa inhibitors rivaroxaban or apixaban, patients receiving home parenteral nutrition for intestinal failure, and individuals with unusual site thrombosis. Moreover, we present the first European study of total, direct and preventable costs of venous thromboembolism and its related complications. We conclude that: 1) prothrombin complex concentrate restores coagulation parameters dose-dependently in subjects treated with rivaroxaban or apixaban, and seems to be safe with respect to thrombotic complications; 2) subjects with intestinal failure treated with home parenteral nutrition are at a very high risk of thrombotic and bleeding complications; moreover, crucial gaps of knowledge regard the efficacy, safety, quality of management and pharmacokinetics of anticoagulants in this specific population; 3) selected patients with short bowel syndrome show a substantial absorption of dabigatran etexilate and rivaroxaban, rendering them an oral alternative to often used parenteral heparins; 4) similarly to venous thromboembolism, cerebral venous thrombosis is strongly associated with the presence of thrombophilia, but thrombophilia testing has a marginal role for the prediction of recurrent thrombotic events; 5) significant cost savings could be achieved if better preventive measures for venous thromboembolism are taken into place within the European Union
Visit from Peter Roche
No full textThe Department of Sociology would like to apply for a grant to bring to our campus Professor Peter Roche de Coppens for two full days. Professor Roche de Coppens is a Professor of Sociology, Anthropology, and Psychotherapy atEast Stroudsburg University and Adjunct Professor of Education at McGill University in Montreal. He is the author of many books in English, French, and ltalian. Dr. Roche de Coppens has lectured at many universities and research centers around the world. He has trained under Pitirim Sorokin, founder of the sociology department at Harvard University, and Roberto Assagioli of Florence, Italy. In addition to his University work Dr. Roche de Coppens has developed his own radio program, Tools for Living and TV program, Soul Sculpture in Pennsylvania. Since 1987 he has acted as a lecturer and consultant for the United Nations. Professor Roche de Coppens during the last 45 years has tried to integrate the finding and insights of social science with spirituality and holistic health\u2
Fundamentals of tri-block copolymer self-assembly in solutions, and its relation to nano-templating
No full textThe purpose of this thesis is to obtain a better understanding of the formation mechanism of mesoporous silica materials, such as SBA-15 that use block copolymers as templating agents. Despite the fact that these materials are now extensively synthesized, the fundamental role of the different synthesis variables has not been determined on the basis of a detailed physical chemical study. Such a synthesis typically starts with the formation of spherical micelles that are converted into long cylindrical micelles during silica hydrolysis and condensation. As a result, a silica matrix with hexagonally ordered mesopores is obtained, after removing the micelles by extraction or calcination. The interactions between the block copolymer and the various additives (silica, acids, salts, solvents) during the first steps of the synthesis in solution are believed to play an important role in the creation of these highly structured materials. Therefore, the emphasis of this thesis lays on providing fundamental information on the self-assembly process of the tri-block copolymer P123 (EO20PO70EO20), typically used in the synthesis of SBA-15, at conditions that mimic those of mesoporous materials synthesis as closely as possible.DelftChemTechApplied Science
Exploring plant co-expression and gene-gene Interactions with CORNET 3.0
No full textSelecting and filtering a reference expression and interaction dataset when studying specific pathways and regulatory interactions can be a very time-consuming and error-prone task. In order to reduce the duplicated efforts required to amass such datasets, we have created the CORNET (CORrelation NETworks) platform which allows for easy access to a wide variety of data types: coexpression data, protein-protein interactions, regulatory interactions, and functional annotations. The CORNET platform outputs its results in either text format or through the Cytoscape framework, which is automatically launched by the CORNET website.CORNET 3.0 is the third iteration of the web platform designed for the user exploration of the coexpression space of plant genomes, with a focus on the model species Arabidopsis thaliana. Here we describe the platform: the tools, data, and best practices when using the platform. We indicate how the platform can be used to infer networks from a set of input genes, such as upregulated genes from an expression experiment. By exploring the network, new target and regulator genes can be discovered, allowing for follow-up experiments and more in-depth study. We also indicate how to avoid common pitfalls when evaluating the networks and how to avoid over interpretation of the results.All CORNET versions are available at http://bioinformatics.psb.ugent.be/cornet/
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