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101.
The cyclic watergas shift reactor (CWGSR) is a cyclically operated fixed bed reactor for the production of hydrogen. It is based on the alternating reduction of an iron oxide fixed bed with synthesis gas and its subsequent oxidation with steam. We show experimental data of moving reaction zones in a tubular CWGSR. Based on this data and to help further design of these reactors, we propose a dynamic, one-dimensional model of the reactor. The formulated process model was fitted to experimental data by adjusting only two parameters describing the catalytic activity and the oxygen capacity of the fixed bed. Exemplary simulation results are shown. 相似文献
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AESOP’s 2009 Congress was hosted by the University of Liverpool as part of the centenary celebration of its Department of Civic Design, the world’s oldest university planning school. ‘Why Can’t the Future be More Like the Past?’ was the conference title on all the banners and conference bags – an oddly querulous question, nevertheless it did the trick in getting participants to think historically throughout AESOP 2009. Michael Hebbert and Dirk Schubert ran a planning history track for six of the conference’s seven parallel session slots. Their call for papers elicited 30 abstracts which reduced to 17 papers, a comfortable quantity allowing good time for presentation and discussion. The track had the fortune to be allocated a wood‐panelled Architecture lecture theatre with superb projection facilities – more than one speaker gasped at the glory of their own PowerPoint images. 相似文献
104.
In project teams that are distributed across the international subsidiaries of a firm, collaboration can be a challenge. The organizational context of projects is not always conducive to international collaboration. Priorities and interests of sub-teams are likely to differ from those of the central team. In a grounded theory study of international client projects in a project-based organization, the impact of organizational context on collaboration is explored. It was found that the organizational context can provide important resources such as authority, policies, procedures and systems that can be appropriated to enable collaboration. However, this applies only when there are drivers for collaboration, consisting of interdependency and interest in the project's success. Even in a context not conducive to collaboration, the drivers encourage teams to constitute informal mechanisms, enabling some level of collaboration. A framework for the impact of organizational context on collaboration in international projects is presented. 相似文献
105.
The role of conductive pathways in the conductivity and rheological behavior of poly(methyl methacrylate)–graphite composites
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Up to now, research on the dynamic process of conductive network formation has tended to focus on composite particles with one‐dimensional geometry, such as carbon black and carbon nanotubes. However, studies on this subject based on fillers with two‐dimensional structure, such as graphite, are rare in the literature. In this work, the dynamic percolation and rheological properties of poly(methyl methacrylate) (PMMA)–graphite composites under an electric field were investigated. The activation energies of conductive network formation and polymer matrix mobility were calculated from the temperature dependence of the percolation time and the zero‐shear viscosity. It was found that the activation energy calculated from the zero‐shear viscosity was not influenced by the electric field in the concentration range investigated, but the electric field had an effect on the activation energy calculated from the percolation time. This finding emphasizes that the electrical and rheological properties have different physical origins. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43810. 相似文献
106.
An Iterative O‐Methyltransferase Catalyzes 1,11‐Dimethylation of Aspergillus fumigatus Fumaric Acid Amides
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Dr. Daniel Kalb Dr. Thorsten Heinekamp Dr. Sebastian Schieferdecker Prof. Dr. Markus Nett Prof. Dr. Axel A. Brakhage Prof. Dr. Dirk Hoffmeister 《Chembiochem : a European journal of chemical biology》2016,17(19):1813-1817
S‐adenosyl‐l ‐methionine (SAM)‐dependent methyltransfer is a common biosynthetic strategy to modify natural products. We investigated the previously uncharacterized Aspergillus fumigatus methyltransferase FtpM, which is encoded next to the bimodular fumaric acid amide synthetase FtpA. Structure elucidation of two new A. fumigatus natural products, the 1,11‐dimethyl esters of fumaryl‐l ‐tyrosine and fumaryl‐l ‐phenylalanine, together with ftpM gene disruption suggested that FtpM catalyzes iterative methylation. Final evidence that a single enzyme repeatedly acts on fumaric acid amides came from an in vitro biochemical investigation with recombinantly produced FtpM. Size‐exclusion chromatography indicated that this methyltransferase is active as a dimer. As ftpA and ftpM homologues are found clustered in other fungi, we expect our work will help to identify and annotate natural product biosynthesis genes in various species. 相似文献
107.
Cover Picture: Reprogramming the Biosynthesis of Cyclodepsipeptide Synthetases to Obtain New Enniatins and Beauvericins (ChemBioChem 4/2016)
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Efficient Engineering and Production Concepts for Products in Regulated Environments – Dream or Nightmare?
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Prof. Jochen Strube Dr. Reinhard Ditz Holger Fröhlich Dr. Dirk Köster Dr. Thomas Grützner Dr. Jörg Koch Dr. Rüdiger Schütte 《化学,工程师,技术》2014,86(5):687-694
Manufacturing of chemical‐pharmaceutical products is moving increasingly fast on a global scale. Therefore, developing and starting up production facilities fast, with high quality, and at reasonable costs has become extremely challenging. Engineering concepts like modularization, standardization and simultaneous/parallel engineering are discussed as methods for speeding up process design and filing for regulatory approval. Transfer from batch to continuous operation mode of production is pointed out as the key‐issue in such strategies. 相似文献