Six Years of Chandra Observations of Supernova Remnants

We present a review of the first six years of Chandra X-ray Observatory observations of supernova remnants. From the official "first-light" observation of Cassiopeia A that revealed for the first time the compact remnant of the explosion, to the recent million-second spectrally-resolved observation that revealed new details of the stellar composition and dynamics of the original explosion, Chandra observations have provided new insights into the supernova phenomenon. We present an admittedly biased overview of six years of these observations, highlighting new discoveries made possible by Chandra's unique capabilities.Comment: 82 pages, 28 figures, for the book Astrophysics Update

Comparison of milk and ethanol/water mixtures with respect to monostyrene migration from a polystyrene packaging material.

Measurement of styrene monomer migration from polystyrene cups into milks containing 0-5, 3-5 or 10 % fat, as well as into four water/ethanol mixtures, containing 0, 15, 50 or 100 % ethanol, indicated that water, the simulant prescribed for milk under EC legislation (Directive 85/572/EEC) does not exhibit the required physico-chemical properties for an adequate simulation under practical migration conditions. Styrene migration was found to depend strongly upon the fat content of the milk and on the ethanol concentration in the simulant. Pure water gave migration values considerably lower than all of the three milks. 50 % ethanol was shown to correlate approximately with 3-5 % fat milk. Measurement of gas/liquid partition coefficients for styrene in the simulants confirmed the findings of the migration test. Higher migration values were found for lower gas/liquid partition coefficients and vice versa. From the kinetic data, an indication of the mechanism of the migration process into m ilk was obtained, leading to the conclusion that the migration rate limiting step is the penetration of the aqueous phase

Mutan produced in potato amyloplasts adheres to starch granules

Production of water-insoluble mutan polymers in Kardal potato tubers was investigated after expression of a full-length (Gtf I) and a truncated mutansucrase gene referred to as GtfICAT (Gtf I without glucan-binding domain) from Streptococcus downei. Subsequent effects on starch biosynthesis at the molecular and biochemical levels were studied. Expression of the GtfICAT gene resulted in the adhesion of mutan material on starch granules, which stained red with erythrosine, and which was hydrolysed by exo-mutanase. In addition, GtfICAT-expressing plants exhibited a severely altered tuber phenotype and starch granule morphology in comparison to those expressing the full-length Gtf I gene. In spite of that, no structural changes at the starch level were observed. Expression levels of the sucrose- regulated, AGPase and GBSSI genes were down-regulated in only the GTFICAT transformants, showing that GtfICAT expression interfered with the starch biosynthetic pathway. In accordance with the down-regulated AGPase gene, a lower starch content was observed in the GTFICAT transformants. Finally, the rheological properties of the GTFICAT starches were modified; they showed a higher retrogradation during cooling of the starch paste