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141.
Zheng Chen Daniel R. Dreyer Zong‐quan Wu Kelly M. Wiggins Zhenhua Jiang Christopher W. Bielawski 《Journal of polymer science. Part A, Polymer chemistry》2011,49(6):1421-1426
The synthesis and characterization of a novel family of main‐chain carbazole‐containing polymers using copper‐catalyzed azide‐alkyne cycloaddition chemistry is reported. The reactions were performed under mild conditions using readily available copper catalysts and ligands, which afforded polymeric products with Mws up to 18 kDa. Using a range of techniques, the polymers were found to exhibit a glass transition temperature (Tg) of 85 °C, high thermal stability (Td = 274 °C), and high photoluminescent quantum efficiency (?f = 0.29; λem = 448 nm), which underscore their potential for use in organic light‐emitting diodes or other emissive devices, particularly where efficient blue emission is of value. The approach described offers practical advantages over other synthetic methods used to prepare main‐chain carbazole‐containing polymers, especially with regard to the lack of need for rigorously inert conditions and the absence of byproducts generated during the polymerization reaction. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011 相似文献
142.
Bin Liu Rupa S. ShettyKristofer K. Moffett Martha J. Kelly 《Tetrahedron letters》2011,52(14):1680-1684
An efficient synthesis of 1,3,5-trisubstituted benzenes via a sequential Pd-mediated carbon-sulfur, carbon-nitrogen, and carbon-carbon bond formation reactions is reported. Selective amidation and sulfonamidation reactions are accomplished via Pd-catalyzed reactions between aryl chlorides and an acetamide or a methanesulfonamide. 相似文献
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144.
John R. Ebdon Barry J. Hunt Paul Joseph Christopher S. Konkel Dennis Price Kelly Pyrah T. Richard Hull G. John Milnes Stephen B. Hill Christopher I. Lindsay John McCluskey Ian Robinson 《Polymer Degradation and Stability》2000,70(3):425-436
Methyl methacrylate (MMA) has been free radically copolymerized, both in bulk and in solution, with diethyl(methacryloyloxymethyl)phosphonate (DEMMP), to give polymers which are significantly flame retarded when compared with PMMA, as indicated by the results of limiting oxygen index (LOI) measurements, UL 94 tests, and the results of cone calorimetric experiments. The physical and mechanical properties of the copolymers are similar to those of PMMA, except that the bulk copolymers are slightly crosslinked, and are better than those of PMMA flame retarded to a similar extent by some phosphate and phosphonate additives. Examination of the some of the gaseous products of pyrolysis and combustion, and of chars produced on burning, show that flame retardation occurs in the copolymers by both a condensed-phase and a vapour-phase mechanism. The condensed-phase mechanism is shown to involve generation of phosphorus acid species followed by reaction of these with MMA units giving rise to methacrylic acid units. The methacrylic acid units subsequently form anhydride links, which probably impede depolymerization of the remaining MMA sequences, resulting in evolution of less MMA (the major fuel when MMA-based polymers burn). By undergoing decarboxylation, leading to interchain cyclisation and, eventually, to aromaticisation, the anhydride units are probably also the principal precursors to char. 相似文献
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147.
Colin M. Mcgill Kristian E. Swearingen Kelly L. Drew Brian T. Rasley Thomas K. Green 《Journal of heterocyclic chemistry》2005,42(4):475-481
Naphthalene‐2,3‐dicarbaldehyde (NDA), a reagent used for the fluorescent detection of amino acids in the presence of cyanide, self‐condenses in the presence of cyanide ion and methanol at room temperature to yield a unique crystalline product 2, 15‐hydroxybenzo[g]benzo[6,7]isochromeno[4,3‐c]isochromen‐7(15H)‐one. The product is proposed to result from facile air oxidation of NDA to a methyl ester in combination with benzoin condensation. Product 2 does not to form in the absence of air. The gHMBC spectrum of 2 distinguishes it from a possible alternative isomeric condensation product. 相似文献
148.
Sônia Cristina Poltroniere Kelly Cristina Poldi Franklina Maria Bragion Toledo Marcos Nereu Arenales 《Annals of Operations Research》2008,157(1):91-104
An important production programming problem arises in paper industries coupling multiple machine scheduling with cutting stocks.
Concerning machine scheduling: how can the production of the quantity of large rolls of paper of different types be determined.
These rolls are cut to meet demand of items. Scheduling that minimizes setups and production costs may produce rolls which
may increase waste in the cutting process. On the other hand, the best number of rolls in the point of view of minimizing
waste may lead to high setup costs. In this paper, coupled modeling and heuristic methods are proposed. Computational experiments
are presented. 相似文献
149.
Joseph H Bunton Jesse D Olson Daniel R Lenz Thomas F Kelly 《Microscopy and microanalysis》2007,13(6):418-427
The performance of the pulsed-laser atom probe can be limited by both instrument and specimen factors. The experiments described in this article were designed to identify these factors so as to provide direction for further instrument and specimen development. Good agreement between voltage-pulsed and laser-pulsed data is found when the effective pulse fraction is less than 0.2 for pulsed-laser mode. Under the conditions reported in this article, the thermal tails of the peaks in the mass spectra did not show any significant change when produced with either a 10-ps or a 120-fs pulsed-laser source. Mass resolving power generally improves as the laser spot size and laser wavelength are decreased and as the specimen tip radius, specimen taper angle, and thermal diffusivity of the specimen material are increased. However, it is shown that two of the materials used in this study, aluminum and stainless steel, depend on these factors differently. A one-dimensional heat flow model is explored to explain these differences. The model correctly predicts the behavior of the aluminum samples, but breaks down for the stainless steel samples when the tip radius is large. A more accurate three-dimensional model is needed to overcome these discrepancies. 相似文献
150.
Campbell Keri Judge Elizabeth J. Dirmyer Matthew R. Kelly Dan Czerwinski Ken 《Journal of Radioanalytical and Nuclear Chemistry》2017,313(1):197-206
Journal of Radioanalytical and Nuclear Chemistry - We report a study of a fast radiochemical method to determine the activity of 131I via the radiochemical recovery obtained with a 129I tracer.... 相似文献