We describe here the most ambitious survey currently planned in the optical, the Large Synoptic Survey Telescope (LSST). The LSST design is driven by four main science themes: probing dark energy and dark matter, taking an inventory of the solar system, exploring the transient optical sky, and mapping the Milky Way. LSST will be a large, wide-field ground-based system designed to obtain repeated images covering the sky visible from Cerro Pachón in northern Chile. The telescope will have an 8.4 m (6.5 m effective) primary mirror, a 9.6 deg 2 field of view, a 3.2-gigapixel camera, and six filters (ugrizy) covering the wavelength range 320-1050 nm. The project is in the construction phase and will begin regular survey operations by 2022. About 90% of the observing time will be devoted to a deep-wide-fast survey mode that will uniformly observe a 18,000 deg 2 region about 800 times (summed over all six bands) during the anticipated 10 yr of operations and will yield a co-added map to r∼27.5. These data will result in databases including about 32 trillion observations of 20 billion galaxies and a similar number of stars, and they will serve the majority of the primary science programs. The remaining 10% of the observing time will be allocated to special projects such as Very Deep and Very Fast time domain surveys, whose details are currently under discussion. We illustrate how the LSST science drivers led to these choices of system parameters, and we describe the expected data products and their characteristics.

Using mellitic acid dianhydride to prepare Zr‐containing pendent copolyimides (co‐PIs) is currently being evaluated as a means of further increasing Zr concentration and atomic oxygen resistance while retaining other desirable film properties. The immediate objectives en route to this ultimate goal are: (1) to address the increased tendency of copolyamic acids (co‐PAAs) to undergo gelation during polymerizations and upon addition of dicyclohexylcarbodiimide during the Zr appending reactions, and (2) for multilayer films, to increase the number of layers that can be applied prior to crack formation. To accomplish these two objectives, a targeted structure–property study has been performed, holding the Zr concentration constant at 10 mol %. The polymer starting materials chosen for this investigation include PMDA and OPDA (dianhydrides), and 4,4′‐ODA, 3,4′‐ODA, and 1,3‐APB (diamines). The spectroscopic data for all polymer products are consistent with the expected amic acid, imide, pendent, and nonpendent structures. Thin‐layer chromatography, viscosity, and gel permeation chromatography (GPC) results confirm the polymeric nature of the Zr pendent and nonpendent co‐PAA precursors, with intrinsic viscosities (η0) of 0.86–0.46 for the former and 0.76–0.38 for the latter. Weight‐average molecular weights are estimated from GPC to be 115,400–436,000 g/mol for the former and 38,300–111,200 g/mol for the latter. While there was little observable effect of structure change on tendency to form gel, APB‐containing Zr pendent copolyimide had the lowest glass transition temperature and allowed the largest number of layers to be cast in a single film without cracking (10 layers) of the pendent copolyimides in this study. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1641–1652, 2007

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The results of a study of compounds in municipal wastewater that are resistant to carbon‐adsorption treatment are reported with emphasis on organic compounds.

For co-polyimides (PIs) of mellitic acid dianhydride, 1,3-aminophenoxybenzene and 4,4′-oxydiphthalic anhydride, Zr-pendent group content could be increased to 50% (mol) improving atomic oxygen (AO) resistance while retaining good film properties. Spectral data are consistent with expected structures. Intrinsic viscosities of 0.54—0.60 dL g—1 and average molecular weights of 111 000—122 000 g mol— 1 estimated from gel permeation chromatography confirm the polymeric nature of co-polyamic acid precursors. Nuclear magnetic resonance integrations and amounts of thermogravimetric analysis residue verify pendent group concentrations. Increasing Zr-pendent group concentration from 10 to 50% (mol) caused glass transition temperatures to increase (198—245 °C), decomposition temperatures to decrease (518—455 °C), and the number of film layers able to be fabricated prior to crack formation to decrease (10 to 8). These numbers of layers were much higher than those for other PIs with comparable Zr-pendent group concentrations. Increased pendent group concentration caused the amount of protective oxide layer formed upon AO exposure to increase.