Interplay of the phase and the chemical composition of the powder feedstock on the properties of porous 8YSZ thermal barrier coatings

Some chemical impurities enhance sintering kinetics of ceramic Thermal Barrier Coatings (TBCs) which can cause their premature failure during operation in gas turbine engine by causing reduction in coating’s strain compliance as well as faster bond-coat oxidation due to increased thermal conductivity. Certain chemical impurities are also believed to suppress resistance to tetragonal to monoclinic phase transformation in 8YSZ, which can also be an important factor regarding TBC’s performance. Most of the impurities and some of the monoclinic phase present in the powder feedstocks can survive into the as-sprayed coating. Therefore, there is a general trend towards OEMs requiring the lowest amounts of chemical impurities and the lowest amounts of monoclinic phase in the powder feedstocks. This paper presents a comprehensive investigation aimed at understanding the role and the relative importance of the chemical and phase purities of the powder feedstock for the properties and performance of thick 8YSZ TBCs.     

Global spatial and temporal distribution of vegetation fire as determined from satellite observations

Vegetation fires occur worldwide, all year round and inject enormous amounts of trace gases and particles into the atmosphere. Nonetheless, there is still great uncertainty as to the global spatial and temporal distribution of vegetation fires. Twenty one months of global, daily, daytime satellite data at 1 km resolution, from April 1992 to December 1993, were processed in order to determine the positions of active vegetation fires. Results from the first twelve months of the study period are presented here. This is the first time that such a global study has been carried out using a long time series data set and a single processing technique. The data set and results discussed provide much improved information on the spatial variability and the seasonality of vegetation fires. They will be of use in the global mapping and modelling of emissions due to biomass burning as well as in the study of the role of fire in land cover maintenance and change. We show that half of the fires detected were on the African continent and over 70% within the tropical belt. Fires were detected in more than 6% of 1 km² pixels, over land, during the 12-month period and savanna grasslands accounted for over one third of this area.     

Techniques for monitoring protein misfolding and aggregation in vitro and in living cells

Protein misfolding and aggregation have been considered important in understanding many neurodegenerative diseases and recombinant biopharmaceutical production. Various traditional and modern techniques have been utilized to monitor protein aggregation in vitro and in living cells. Fibril formation, morphology and secondary structure content of amyloidogenic proteins in vitro have been monitored by molecular probes, TEM/AFM, and CD/FTIR analyses, respectively. Protein aggregation in living cells has been qualitatively or quantitatively monitored by numerous molecular folding reporters based on either fluorescent protein or enzyme. Aggregation of a target protein is directly correlated to the changes in fluorescence or enzyme activity of the folding reporter fused to the target protein, which allows non-invasive monitoring aggregation of the target protein in living cells. Advances in the techniques used to monitor protein aggregation in vitro and in living cells have greatly facilitated the understanding of the molecular mechanism of amyloidogenic protein aggregation associated with neurodegenerative diseases, optimizing culture conditions to reduce aggregation of biopharmaceuticals expressed in living cells, and screening of small molecule libraries in the search for protein aggregation inhibitors.     

Defensive secretion of the carabid beetlePasimachus subsulcatus

The defensive secretion of the carabid beetlePasimachus subsulcatus is a concentrated solution (up to 90%) of carboxylic acids, amounting to about 1% of body mass. It contains three major components (methacrylic, tiglic, and angelic acids) and four minor components (isobutyric, 2-methyl-butyric, isovaleric, and senecioic acids). In the single population of this large flightless beetle that was examined, the relative ratio of acidic components was remarkably constant from individual to individual.Report No. 87 of the series Defense Mechanisms of Arthropods; No. 86 is Dussourd, D., et al.,Proc. Natl. Acad. Sci. 85, 5992 (1988).     

Nitrogen impurity effects on nickel silicide formation at low temperatures - New “nitrogen co-plasma” approach

Nickel based silicide films were prepared by annealing nickel-platinum layers deposited on n doped Si substrates. We report on the evolution of the phase formation and the redistribution of contaminants on blanket wafers during silicide formation as a function of the nitrogen gas flow introduces during Ni(Pt) deposition. Nitrogen incorporation creates a contamination as-deposited layer which modifies phase formation and changes nickel diffusion. Nitrogen is not incorporated in silicide formed. After a second anneal, the monosilicide forms excepted for high nitrogen quantity introduced where the Ni₃Si₂ is always observed. Monosilicide thermal stability is also improved by nitrogen co-plasma.     

Three-dimensional analysis of a compression test on stone wool

A full three-dimensional (3D) study of a compression test on a sample made of stone wool is presented. The analysis combines different tools, namely X-ray microtomography of an in situ experiment, image acquisition and treatment, and volume correlation. This set of tools allows for the measurement of 3D displacement fields and enables Poisson’s ratio of this type of material to be evaluated. The strain fields are used to analyze localization phenomena. The uncertainty of the analysis is evaluated by actually moving the sample in its undeformed and deformed states, qualifying both image acquisition and correlation steps.     

Extrusion of feather keratin

Keratin obtained from poultry feathers was extruded at 120°C using a combination of glycerol, water, and sodium sulfite as processing aids. Rheological properties were assessed as a function of water, glycerol, and sodium sulfite content as well as extruder die temperature. The lowest viscosity blends at a constant feather keratin concentration of 60 wt % were found at glycerol concentrations that were higher than the water concentration and sodium sulfite concentrations of 3–4 wt % of the feather keratin fraction. For the melt state, higher or lower sodium sulfite concentrations resulted in increased viscosity. In the solid state, it was observed that processing induced orientation increased the tensile properties of the extrudates. Raman spectroscopy and DSC showed that there was a transition from α‐helix to β‐sheet at sodium sulfite concentrations of less than 4 wt %. At greater sodium sulfite concentration, increased crystallinity was found, because keratin chains could be extended more during processing. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1432–1442, 2006     

A wavelet transform algorithm for peak detection and application to powder x-ray diffraction data

Peak detection is ubiquitous in the analysis of spectral data. While many noise-filtering algorithms and peak identification algorithms have been developed, recent work [P. Du, W. Kibbe, and S. Lin, Bioinformatics 22, 2059 (2006); A. Wee, D. Grayden, Y. Zhu, K. Petkovic-Duran, and D. Smith, Electrophoresis 29, 4215 (2008)] has demonstrated that both of these tasks are efficiently performed through analysis of the wavelet transform of the data. In this paper, we present a wavelet-based peak detection algorithm with user-defined parameters that can be readily applied to the application of any spectral data. Particular attention is given to the algorithm's resolution of overlapping peaks. The algorithm is implemented for the analysis of powder diffraction data, and successful detection of Bragg peaks is demonstrated for both low signal-to-noise data from theta-theta diffraction of nanoparticles and combinatorial x-ray diffraction data from a composition spread thin film. These datasets have different types of background signals which are effectively removed in the wavelet-based method, and the results demonstrate that the algorithm provides a robust method for automated peak detection.     

Receptor cells inIps typographus andDendroctonus micans specific to pheromones of the reciprocal genus

Olfactory receptor cells were studied electrophysiologically inIps typographus andDendroctonus micans. The investigation revealed cells which were keyed to pheromone compounds characteristic of the reciprocal genus. Thus, cells keyed toexo-brevicomin were found inI. typographus, whereas cells keyed to (+)-ipsdienol were present inD. micans. Laboratory behavioral tests indicated an attractive effect of the two compounds on beetles of the reciprocal genus. InI. typographus the effect ofexo-brevicomin predominantly concerned males and enhanced their response to the pheromone ipslure. It is suggested thatexo-brevicomin serves as an interspecific attractant forI. typographus, which may be guided by pheromone compounds of the reciprocal genus in finding suitable breeding material. The function of (+)-ipsdienol inD. micans is more uncertain. It may be either a pheromone or an interspecific messenger.