Magnetism dependent phonon anomaly in LaFeAsO observed via inelastic x-ray scattering

The phonon dispersion was measured at room temperature along (0,0,L) in the tetragonal phase of LaFeAsO using inelastic x-ray scattering. Spin-polarized first-principles calculations imposing various types of antiferromagnetic order are in better agreement with the experimental results than nonmagnetic calculations, although the measurements were made well above the magnetic ordering temperature, T_N. Splitting observed between two A_{1g} phonon modes at 22 and 26 meV is only observed in spin-polarized calculations. Magneto-structural effects similar to those observed in the AFe_2As_2 materials are confirmed present in LaFeAsO. The presence of Fe-spin is necessary to find reasonable agreement of the calculations with the measured spectrum well above T_N. On-site Fe and As force constants show significant softening compared to nonmagnetic calculations, however an investigation of the real-space force constants associates the magnetoelastic coupling with a complex renormalization instead of softening of a specific pairwise force.Comment: 7 pages, 4 figure

Preliminary Solar Sail Design and Fabrication Assessment: Spinning Sail Blade, Square Sail Sheet

Blade design aspects most affecting producibility and means of measurement and control of length, scallop, fullness and straightness requirements and tolerances were extensively considered. Alternate designs of the panel seams and edge reinforcing members are believed to offer advantages of seam integrity, producibility, reliability, cost and weight. Approaches to and requirements for highly specialized metalizing methods, processes and equipment were studied and identified. Alternate methods of sail blade fabrication and related special machinery, tooling, fixtures and trade offs were examined. A preferred and recommended approach is also described. Quality control plans, inspection procedures, flow charts and special test equipment associated with the preferred manufacturing method were analyzed and are discussed

The NILE Project — Advances in the Conversion of Lignocellulosic Materials into Ethanol

NILE ("New Improvements for Lignocellulosic Ethanol") was an integrated European project (2005-2010) devoted to the conversion of lignocellulosic raw materials to ethanol. The main objectives were to design novel enzymes suitable for the hydrolysis of cellulose to glucose and new yeast strains able to efficiently converting all the sugars present in lignocellulose into ethanol. The project also included testing these new developments in an integrated pilot plant and evaluating the environmental and socio-economic impacts of implementing lignocellulosic ethanol on a large scale. Two model raw materials – spruce and wheat straw – both preconditioned with similar pretreatments, were used. Several approaches were explored to improve the saccharification of these pretreated raw materials such as searching for new efficient enzymes and enzyme engineering. Various genetic engineering methods were applied to obtain stable xylose- and arabinose-fermenting Saccharomyces cerevisiae strains that tolerate the toxic compounds present in lignocellulosic hydrolysates. The pilot plant was able to treat 2 tons of dry matter per day, and hydrolysis and fermentation could be run successively or simultaneously. A global model integrating the supply chain was used to assess the performance of lignocellulosic ethanol from an economical and environmental perspective. It was found that directed evolution of a specific enzyme of the cellulolytic cocktail produced by the industrial fungus, Trichoderma reesei, and modification of the composition of this cocktail led to improvements of the enzymatic hydrolysis of pretreated raw material. These results, however, were difficult to reproduce at a large scale. A substantial increase in the ethanol conversion yield and in specific ethanol productivity was obtained through a combination of metabolic engineering of yeast strains and fermentation process development. Pilot trials confirmed the good behaviour of the yeast strains in industrial conditions as well as the suitability of lignin residues as fuels. The ethanol cost and the greenhouse gas emissions were highly dependent on the supply chain but the best performing supply chains showed environmental and economic benefits. From a global standpoint, the results showed the necessity for an optimal integration of the process to co-develop all the steps of the process and to test the improvements in a flexible pilot plant, thus allowing the comparison of various configurations and their economic and environmental impacts to be determined. <br> Le projet NILE, acronyme de "New Improvements for Lignocellulosic Ethanol", était un projet européen (2005-2010) consacré à la conversion des matières premières lignocellulosiques en éthanol. Ses principaux objectifs étaient de concevoir de nouvelles enzymes adaptées à l’hydrolyse de la cellulose en glucose et de nouvelles souches de levure capables de convertir efficacement tous les sucres présents dans la lignocellulose en éthanol. Une autre partie du projet consistait à tester ces nouveaux systèmes dans une installation pilote et à évaluer les impacts environnementaux et socio-économiques de la production et utilisation à grande échelle d’éthanol lignocellulosique. Deux matières premières modèles (l’épicéa et la paille de blé) prétraitées de façon semblable, ont été étudiées. Différentes approches ont été tentées pour améliorer la saccharification de ces matières premières, par exemple, la recherche de nouvelles enzymes efficaces ou l’ingénierie d’enzymes. Plusieurs stratégies d’ingénierie génétique ont été utilisées pour obtenir des souches stables de Saccharomyces cerevisiae capables de fermenter le xylose et l’arabinose, et de tolérer les composés toxiques présents dans les hydrolysats lignocellulosiques. L’installation pilote pouvait traiter 2 tonnes de matières sèches par jour, et l’hydrolyse et la fermentation pouvaient être menées successivement ou simultanément. Un modèle global intégrant la chaîne d’approvisionnement en matière première a servi à évaluer les performances économiques et environnementales de la production d’éthanol lignocellulosique. L’évolution dirigée d’une enzyme du cocktail cellulolytique produit par le champignon Trichoderma reesei, et la modification de la composition de ce cocktail améliorent l’hydrolyse enzymatique des matières premières prétraitées. Cependant, ces résultats n’ont pu être reproduits à grande échelle. Le rendement de conversion et la productivité spécifique en éthanol ont été sensiblement augmentés grâce à l’ingénierie métabolique des souches de levure et au développement d’un procédé optimal de fermentation. Les essais en pilote ont confirmé le bon comportement de ces souches de levure en conditions industrielles ainsi que la possibilité d’utiliser les résidus riches en lignine comme combustible. Le coût de production de l’éthanol et le bilan des émissions de gaz à effet de serre étaient très dépendants des sources d’énergie utilisées. D’un point de vue plus global, les résultats ont montré que l’optimisation du procédé nécessite de codévelopper toutes les étapes de façon intégrée et de valider les améliorations dans une installation pilote, afin notamment de pouvoir comparer différentes configurations et d’en déterminer les effets sur l’économie du procédé et ses impacts environnementaux