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81.
Rouaix Sandrine Laurent Cantrel Armand Yves Mattei Jean-Marie Liska Marek Galuskova Dagmar Vicena Yvan Soltesz Bela 《Chemical Engineering Research and Design》2008,86(6):633
For many years, the French “Institut de Radioprotection et de Sûreté Nucléaire” has developed studies concerning chemical effects, which can occur during a loss of coolant accident (LOCA) on a nuclear power plant, due to precipitate formation leading to an increase of head loss to sump screens. This increase can cause the loss of emergency core cooling system (ECCS) and of the containment spray system (CSS), which are the two removal heat safety systems which ensure the accident mitigation.These precipitates are formed by recombination of mineral species, which are released due to corrosion of immersed debris (particles of concrete, glass fibre insulation, piece of paint…). PHREEQC software has been used to identify nature and mass of precipitates that can be formed during a LOCA.This report presents the results of sensitivity studies carried out with PHREEQC. Chemical precipitate formation is studied as a function of several physical parameters, such as temperature, pH, nature and debris concentration. The optimal conditions in order to reduce the formation of precipitates are drawn from these calculations. 相似文献
82.
A central ability of the motor system is to achieve goals with great reliability, although never with zero variability. It is argued that variability is reduced with practice by 3 separate means: reduction of stochastic noise (N), exploitation of task tolerance (T), and covariation (C) between central variables. A method is presented that decomposes variability into these components in relation to task space that is defined by the execution variables. Successful variable combinations form the solution manifold. In a virtual skittles task, it is demonstrated that participants' improvement over repetitions, indicated by increasing accuracy, is accounted for by N, T, and, to a lesser degree, C. The relative contribution of these components changes over the course of practice and task variations. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
83.
Quantitative Erfassung der Nitride im austenitischen Stahl X 2 CrNiN 19 9 zur Beschreibung des Ausscheidungsverhaltens durch chemische und elektrochemische sowie Röntgenfeinstruktur- und elektronenoptische Untersuchungen. Ermittlung der Kornzerfallanfälligkeit durch Korrosionsprüfungen nach Strauß und Huey. Vergleich des Verhaltens gegenüber Kornzerfall mit den Nitridausscheidungen. 相似文献
84.
Shaun Hay Kenton Thiessen Dagmar Svecova Baidar Bakht 《Canadian Metallurgical Quarterly》2006,10(6):483-491
The objective of this study was to develop a cost-effective shear-strengthening technique for timber stringers that is environmentally friendly and leads to a durable structure. Testing was performed on creosote-treated Douglas fir beams, with dimensions of 100×400×3,650?mm, removed from a 40 year old bridge. Two strengthening schemes were investigated; incorporating vertical and diagonal glass fiber-reinforced polymer (GFRP) sheets applied to both shear spans. The diagonal scheme proved effective in increasing the average ultimate load, flexural stiffness, and deformability of the beams. Performance of the members reinforced using the vertical scheme, however, was poor compared to diagonally reinforced beams. The contribution of the diagonal sheets to the shear capacity of the stringers was around 12% at service loads and 40% at ultimate load. In conclusion, this study has shown that diagonal GFRP sheets are more effective than vertical sheets in shear-strengthening timber stringers with horizontal splits at their ends. 相似文献
85.
Sternad Dagmar; Duarte Marcos; Katsumata Hiromu; Schaal Stefan 《Canadian Metallurgical Quarterly》2001,27(5):1163
Rhythmically bouncing a ball with a racket was investigated and modeled with a nonlinear map. Model analyses provided a variable defining a dynamically stable solution that obviates computationally expensive corrections. Three experiments evaluated whether dynamic stability is optimized and what perceptual support is necessary for stable behavior. Two hypotheses were tested: (a) Performance is stable if racket acceleration is negative at impact, and (b) variability is lowest at an impact acceleration between -4 and -1 m/s2. In Experiment 1 participants performed the task, eyes open or closed, bouncing a ball confined to a 1-dimensional trajectory. Experiment 2 eliminated constraints on racket and ball trajectory. Experiment 3 excluded visual or haptic information. Movements were performed with negative racket accelerations in the range of highest stability. Performance with eyes closed was more variable, leaving acceleration unaffected. With haptic information, performance was more stable than with visual information alone. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
86.
87.
Alena Nprstkov Kateina Malínsk Lenka Zvesk Drbkov Elodie Billey Dagmar Nprstkov Eva Sýkorov Ccile Bousquet-Antonelli David Honys 《International journal of molecular sciences》2021,22(4)
ALBA DNA/RNA-binding proteins form an ancient family, which in eukaryotes diversified into two Rpp25-like and Rpp20-like subfamilies. In most studied model organisms, their function remains unclear, but they are usually associated with RNA metabolism, mRNA translatability and stress response. In plants, the enriched number of ALBA family members remains poorly understood. Here, we studied ALBA dynamics during reproductive development in Arabidopsis at the levels of gene expression and protein localization, both under standard conditions and following heat stress. In generative tissues, ALBA proteins showed the strongest signal in mature pollen where they localized predominantly in cytoplasmic foci, particularly in regions surrounding the vegetative nucleus and sperm cells. Finally, we demonstrated the involvement of two Rpp25-like subfamily members ALBA4 and ALBA6 in RNA metabolism in mature pollen supported by their co-localization with poly(A)-binding protein 3 (PABP3). Collectively, we demonstrated the engagement of ALBA proteins in male reproductive development and the heat stress response, highlighting the involvement of ALBA4 and ALBA6 in RNA metabolism, storage and/or translational control in pollen upon heat stress. Such dynamic re-localization of ALBA proteins in a controlled, developmentally and environmentally regulated manner, likely reflects not only their redundancy but also their possible functional diversification in plants. 相似文献
88.
Dagmar Ammelt Alica Lammerskitten Artur Wiktor Francisco J. Barba Stefan Toepfl Oleksii Parniakov 《International Journal of Food Science & Technology》2021,56(4):1777-1787
The effect of pulsed electric fields (PEF) on the cell disintegration index (Zp), the freeze-drying process and the final product quality of red beet and pineapple tissue was studied. Red beets and pineapples were PEF-treated at an electric field strength of 1.07 kV/cm and specific energy inputs of 1 kJ/kg and 4 kJ/kg (PEF1 and PEF2, respectively). Freeze-drying was performed at a pressure of 1 mbar and heating plate temperature of 50 °C for red beet and 40 °C for pineapple. The quality of freeze-dried tissue was evaluated by the analysis of residual moisture content, macrostructure, texture, colour and rehydration properties. For freeze-dried red beets, the betalain content from extracts was studied. It could be stated that PEF pre-treatment had no significant influence on drying time reduction, however significantly improved the final quality of freeze-dried product. Moreover, the effect of PEF was strongly depending on type of plant material used. 相似文献
89.
The role of phase-transfer catalysts (PTC) (ammonium and phosphonium salts) with various anions on the biphasic oxidative cleavage of long chain olefins with aqueous hydrogen peroxide catalyzed by Na2WO4/H3PO4/PTC system has been investigated. It was shown that the nature of PTC widely affects the catalytic activity of the above system in the conversion of alkenes, cycloalkenes and unsaturated fatty acids into carboxylic acids.
相似文献90.
Biosynthesis of the Fluorinated Natural Product Nucleocidin in Streptomyces calvus Is Dependent on the bldA‐Specified Leu‐tRNAUUA Molecule
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Xi Ming Zhu Stefanie Hackl Dr. Maulik N. Thaker Dr. Lindsay Kalan Claudia Weber Dr. Dagmar S. Urgast Dr. Eva M. Krupp Alyssa Brewer Stephanie Vanner Anjuli Szawiola Grace Yim Prof. Jörg Feldmann Prof. Andreas Bechthold Prof. Gerard D. Wright Prof. David L. Zechel 《Chembiochem : a European journal of chemical biology》2015,16(17):2498-2506
Nucleocidin is one of the very few natural products known to contain fluorine. Mysteriously, the nucleocidin producer Streptomyces calvus ATCC 13382 has not been observed to synthesize the compound since its discovery in 1956. Here, we report that complementation of S. calvus ATCC 13382 with a functional bldA‐encoded Leu‐tRNAUUA molecule restores the production of nucleocidin. Nucleocidin was detected in culture extracts by 19F NMR spectroscopy, HPLC‐ESI‐MS, and HPLC‐continuum source molecular absorption spectroscopy for fluorine‐specific detection. The molecule was purified from a large‐scale culture and definitively characterized by NMR spectroscopy and high‐resolution MS. The nucleocidin biosynthetic gene cluster was identified by the presence of genes encoding the 5′‐O‐sulfamate moiety and confirmed by gene disruption. Two of the genes within the nucleocidin biosynthetic gene cluster contain TTA codons, thus explaining the dependence on bldA and resolving a 60‐year‐old mystery. 相似文献