960 research outputs found

    Synthesis and Evaluation of Some Coumarin Containing Potential Antimicrobial Agents

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    A series of the Schiff’s bases incorporating coumarin and chalcone moeities, 3-(4-(4-(substituted phenyl)prop-1-ene-3-one) phenylimino) methyl)-4-chloro-2h-chromen-2-one 4(a-g) were synthesized as potential antimicrobial agents. These compounds were characterized on the basis of their spectral (IR, 1H NMR) data and evaluated for antimicrobial activity in vitro against gram positive and gram negative bacteria and fungi. Compound 4b was found to be most active with an MIC of 20 µg/mL against all the tested organisms

    GALEX J201337.6+092801: The lowest gravity subdwarf B pulsator

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    We present the recent discovery of a new subdwarf B variable (sdBV), with an exceptionally low surface gravity. Our spectroscopy of J20136+0928 places it at Teff = 32100 +/- 500, log(g) = 5.15 +/- 0.10, and log(He/H) = -2.8 +/- 0.1. With a magnitude of B = 12.0, it is the second brightest V361 Hya star ever found. Photometry from three different observatories reveals a temporal spectrum with eleven clearly detected periods in the range 376 to 566 s, and at least five more close to our detection limit. These periods are unusually long for the V361 Hya class of short-period sdBV pulsators, but not unreasonable for p- and g-modes close to the radial fundamental, given its low surface gravity. Of the ~50 short period sdB pulsators known to date, only a single one has been found to have comparable spectroscopic parameters to J20136+0928. This is the enigmatic high-amplitude pulsator V338 Ser, and we conclude that J20136+0928 is the second example of this rare subclass of sdB pulsators located well above the canonical extreme horizontal branch in the HR diagram.Comment: 5 pages, accepted for publication in ApJ Letter

    Modifications in biphasic liquid-scintillation vial system for radiometry

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    Several modifications of the biphasic liquid-scintillation vial system for radiometry have been tried in order to improve the counting efficiency. The biphasic system consisted of an inner sterile vial containing medium and substrate, and an outer liquid-scintillation vial lined on the inside with filter paper impregnated with scintillation fluors and alkali. The system gave an overall counting efficiency of 14.6%. Substitution of methanolic NaOH for impregnation of the paper raised the counting efficiency to 29.1%. This could be further enhanced to 33.8% by lining only half of the outer vial with filter paper, thereby allowing improved optical transmission of scintillation light. Increasing the amount of fluor did not change the efficiency significantly. A complete interchange in the system, whereby half of the inner vial was lined with filter paper and was otherwise empty, while the outer vial contained the medium and substrate, gave the highest efficiency (36.9%). This also allowed the use of larger amounts of medium and the inoculum

    Effects of infliximab on markers of inflammation and bone turnover and associations with bone mineral density in patients with ankylosing spondylitis

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    Using a micro-extruder a new class of polyurethanes, polyacylurethanes (PAUs), based on poly (epsilon-caprol actone) (PCL) oligomers and terephthaloyl diisocyanate was synthesized. These polymers are anticipated to have potential for biodegradable and/or biomedical applications. Therefore, PAUs were synthesized without the use of any, possibly toxic, catalysts. PCL diols of different molecular mass were used, namely 750, 1000, 1250, 1500, 2000, 3000 and 4000 g/mol. These diols were synthesized by thermal polymerization at 150 degrees C without the use of any catalyst. The PAUs of terephthaloyl diisocyanate were synthesized by reactive extrusion using a micro-extruder of 5 cm 3 at 130 degrees C. The PAUs obtained were characterized using DSC, GPC, DMTA, SAXS and tensile testing. Surprisingly, PAUs based on PCL chains of 750, 1000, 1250 and 1500 g/mol were found to show microphase separation/micro crystallization as proven by SAXS data combined with DSC. This microphase separation creates elastomeric properties as is known from polyurethanes. In the PAUs based on PCL chains of 2000, 3000 and 4000 g/mol part of the PCL was found to crystallize and no evidence of any phase separation of the acylurethane block was found. (c) 2005 Elsevier Ltd. All rights reserved

    On the structure of Borel stable abelian subalgebras in infinitesimal symmetric spaces

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    Let g=g_0+g_1 be a Z_2-graded Lie algebra. We study the posets of abelian subalgebras of g_1 which are stable w.r.t. a Borel subalgebra of g_0. In particular, we find out a natural parametrization of maximal elements and dimension formulas for them. We recover as special cases several results of Kostant, Panyushev, Suter.Comment: Latex file, 35 pages, minor corrections, some examples added. To appear in Selecta Mathematic
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