Effect of oxide films on hydrogen permeability of candidate Stirling engine heater head tube alloys

The effect of oxide films developed in situ from CO/CO2 doped hydrogen on high pressure hydrogen permeability at 820 C was studied on N-155, A-286, IN 800, 19-9DL, Nitronic 40, HS-188, and IN 718 tubing in a Stirling materials simulator. The hydrogen permeability decreased with increasing dopant levels of CO or CO2 and corresponding decreases in oxide porosity. Minor reactive alloying elements strongly influenced permeability. At high levels of CO or CO2, a liquid oxide formed on alloys with greater than 50 percent Fe. This caused increased permeability. The oxides formed on the inside tube walls were analyzed and their effective permeabilities were calculated

Effect of W and WC on the oxidation resistance of yttria-doped silicon nitride

The effect of W and WC contamination on the oxidation and cracking in air of sintered Si3N4 - 8 w/o Y2O3 ceramics at 500, 750, and 1350 C is examined. A mixture of Si3N4 - 8Y2O3, milled with alumina balls, was divided into four portions. Three portions were doped with 2 w/o WC W, and 4 w/o W respectively, in order to simulate contamination during milling. The fourth portion was undoped and used on a control. The addition of W or WC did not affect the phase relationships in the system, as all bars with or without additions contained melilite as the major Si-Y-O-N phase after sintering. At 750 C, instability (rapid oxidation and cracking) of W-doped bars appears to have occurred as a result of oxidation of the tungsten containing melilite phase. No intermediate temperature instability was observed in bars containing 2 w/o WC or in bars with no additive. Specimens exposed at 1350 C had good oxidation resistance due to the formation of a protective siliceous oxide layer. A specimen containing 4 w/o W which was preoxidized at 1350 C had improved oxidation resistance at 750 C. The tendency towards oxidation and cracking of Si3N4 - 8 Y2O3 at 750 C is concluded to be related to tungsten content of the sintered bars

Effect of starting powder characteristics on density, microstructure and low temperature oxidation behavior of a Si3N48w/o Y2O3 ceramic

The densification and oxidation behavior of Si3N4 - 8w/oY2O3 prepared from three commercial starting powders were studied. Bars of SN 402, SN 502, and CP 85/15 were sintered for 3 to 4.5 hours at 1750 C. A second set was hot pressed for 2 hours at 1750 C. The microstructures were studied by transmission electron microscopy and scanning electron microscopy, densities were determined, and the phase compositions were determined by X-ray diffraction. Densification and microstructure were greatly influenced by the starting powder morphology and impurity content. Although SN 402 exhibited the maximum weight lose, the highest sintered and hot pressed densities were obtained with this powder. All powders had both equiaxed and elongated grains. Sintered bars were composed of beta silicon nitride and n-melelite. In contrast, hot pressed bars contained beta silicon nitride, H-phase, and J-phase, but no melelite. Yttria distribution in sintered bars was related to the presence of cation impurities such as Ca, Fe, and Mg. A limited oxidation study at 750 C in air showed no instability in these Si3N4 - 8 w/oY2O3 specimens, regardless of startin powder

Effects of chromium and aluminum on mechanical and oxidation properties of iron-nickel-base superalloys based on CG-27

The effects of chromium and aluminum on the mechanical and oxidation properties of a series of gamma-prime-strengthened alloys based on CG-27 were studied. Gamma-prime dispersion and solid-solution strengthening were the principal modes of alloy strengthening. The oxidation attack parameter K sub a decreased with increasing Cr and Al contents for each alloy group based on Al content. As a group, alloys with 3 wt % Al had the lowest attack parameters. Therefore, 3 wt % is the optimum level of Al for parabolic oxidation behavior. Spalling, due to diffusion-induced grain growth, was controlled by the overall Cr and Al levels. The alloy with 4 wt % Cr and 3 wt % Al had stress-rupture properties superior to those of the base alloy, CG-27, and maintained parabolic oxidation behavior while the Cr content was reduced by two-thirds of its value in cast CG-27

Vergleich der biomechanischen Stabilität verschiedener Osteosynthesesysteme am Unterkiefer, eine experimentelle und finite Elemente gestützte Analyse

Ziel der Osteosynthese des frakturierten oder osteotomierten Unterkiefers ist es, frühzeitig unter physiologischer Belastung stabil zu sein und zugleich durch hinreichende Flexibilität eine physiologische Osteoblastenstimulation zu erreichen. Wir vergleichen bikortikale rigide Systeme (DCP, EDCP), übungsstabile Miniplatten sowie moderne 3-D-Plattensysteme. In dieser Arbeit wurden mazerierte humane Unterkiefer (n=6) standardisiert frakturiert (n=5) bzw. osteotomiert (n=1). Die osteosynthetisierten Kiefer wurden durch linear steigenden okklusalen Druck inzisal, prämolar bds. und molar bds. belastet. Die resultierenden Längenänderungen unter simulierter physiologischer Belastung wurden durch Dehnungsmeßstreifen auf der Knochenoberfläche erfaßt. Für die Stabilität ist primär die exakte Reposition entscheidend. Die 3-dimensinale Stabilität in einem physiologischen Bewegungsfenster ist vor allem durch 3-D-Platten aber auch Miniplatten zu erreichen

Wahrnehmung und Darstellung von Wirklichkeit in der Krise : Exemplarische Analysen zu Realismuskonzepten vonÉdouard Manet und Edgar Degas

Das komplexe und widersprüchliche Realismuskonzept im Werk von Edouard Manet und Edgar Degas wird anhand zweier Fallbeispiele untersucht: Manets umstrittenes „Akt“- Gemälde der Olympia und Degas` Skulptur Kleine Tänzerin von Vierzehn Jahren. Die einzigartige Erscheinung der Wachsfigurine von Degas bringt durch den Einsatz ungewöhnlicher Materialien eine Fusion aus Kunst, Geschichte, Wissenschaft und populärer Kultur zur Darstellung. Vor den soziohistorischen Umbrüchen des 19. Jahrhunderts interpretiere ich den paradoxen Realismus der Fallbeispiele als kunsthistorische Stellungnahmen zur damaligen Krise der Wirklichkeitswahrnehmung und -darstellung in der fortschrittlichen Kunst des 19. Jahrhunderts, welche die Historische Moderne einleitet. Ziel der Arbeit ist es zu zeigen, dass Manets und Degas´ Fallbeispiele als „Ästhetisierungen von Realitätsfragmenten“ Entsprechungen in der veränderten Wahrnehmung des 19. Jahrhunderts finden. Die Erfahrung von Wirklichkeit wurde als komplex und subjektiv erkannt, was die Unmöglichkeit einer objektiven Sicht betont. Die Fallbeispiele können hier das Oxymoron Realismus entlarven. Sie bestätigen, dass die flüchtige, unbeständige Lebenswirklichkeit - die damals mit der beschleunigten und die Sinne überreizenden Großstadtwahrnehmung verbunden wurde - nicht als künstlerische Umsetzung abbildbar ist, im Kunstwerk jedoch erfahrbar gemacht werden kann

KIC InnoEnergy Project Neptune: development of a floating LiDAR buoy for wind, wave and current measurements

The KIC-InnoEnergy project “NEPTUNE” develops a floating Lidar buoy and a hindcast- and forecast model for wind- wave- and current measurements of offshore wind farms. In this paper just the lidar buoy is presented and discussed: Main challenges, the design ideas and the steps to develop, test and prototype this product, which – according to the KIC-InnoEnergy project idea – should be commercialized after the project end, foreseen for the end of 2014. KIC-InnoEnergy is funded from the European Institute of Technology, EIT.Peer ReviewedPostprint (published version

Genotype-Environment Interactions Reveal Causal Pathways That Mediate Genetic Effects on Phenotype

Unraveling the molecular processes that lead from genotype to phenotype is crucial for the understanding and effective treatment of genetic diseases. Knowledge of the causative genetic defect most often does not enable treatment; therefore, causal intermediates between genotype and phenotype constitute valuable candidates for molecular intervention points that can be therapeutically targeted. Mapping genetic determinants of gene expression levels (also known as expression quantitative trait loci or eQTL studies) is frequently used for this purpose, yet distinguishing causation from correlation remains a significant challenge. Here, we address this challenge using extensive, multi-environment gene expression and fitness profiling of hundreds of genetically diverse yeast strains, in order to identify truly causal intermediate genes that condition fitness in a given environment. Using functional genomics assays, we show that the predictive power of eQTL studies for inferring causal intermediate genes is poor unless performed across multiple environments. Surprisingly, although the effects of genotype on fitness depended strongly on environment, causal intermediates could be most reliably predicted from genetic effects on expression present in all environments. Our results indicate a mechanism explaining this apparent paradox, whereby immediate molecular consequences of genetic variation are shared across environments, and environment-dependent phenotypic effects result from downstream integration of environmental signals. We developed a statistical model to predict causal intermediates that leverages this insight, yielding over 400 transcripts, for the majority of which we experimentally validated their role in conditioning fitness. Our findings have implications for the design and analysis of clinical omics studies aimed at discovering personalized targets for molecular intervention, suggesting that inferring causation in a single cellular context can benefit from molecular profiling in multiple contexts

Deep offshore wind farm planning and cost calculation tools

Postprint (published version