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91.
The novel carboxamide-pyridine N-oxide synthon, sustained via N-H...O- hydrogen bonding and C-H...O interaction, is shown to assemble isonicotinamide N-oxide in a triple helix architecture and the same heterosynthon is exploited to synthesize cocrystals of barbiturate drugs with 4,4'-bipyridine N,N'-dioxide. 相似文献
92.
Cheol Park John Wilkinson Sumanth Banda Zoubeida Ounaies Kristopher E. Wise Godfrey Sauti Peter T. Lillehei Joycelyn S. Harrison 《Journal of Polymer Science.Polymer Physics》2006,44(12):1751-1762
While high shear alignment has been shown to improve the mechanical properties of single‐wall carbon nanotube (SWNT)‐polymer composites, this method does not allow for control over the electrical and dielectric properties of the composite and often results in degradation of these properties. Here, we report a novel method to actively align SWNTs in a polymer matrix, which permits control over the degree of alignment of the SWNTs without the side effects of shear alignment. In this process, SWNTs were aligned via AC field‐induced dipolar interactions among the nanotubes in a liquid matrix followed by immobilization by photopolymerization under continued application of the electric field. Alignment of SWNTs was controlled as a function of magnitude, frequency, and application time of the applied electric field. The degree of SWNT alignment was assessed using optical microscopy and polarized Raman spectroscopy, and the morphology of the aligned nanocomposites was investigated by high‐resolution scanning electron microscopy. The structure of the field induced aligned SWNTs was intrinsically different from that of shear aligned SWNTs. In the present work, SWNTs are not only aligned along the field, but also migrate laterally to form thick, aligned SWNT percolative columns between the electrodes. The actively aligned SWNTs amplify the electrical and dielectric properties of the composite. All of these properties of the aligned nanocomposites exhibited anisotropic characteristics, which were controllable by tuning the applied field parameters. © 2006 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 44: 1751–1762, 2006 相似文献
93.
The hypersonic flow fields around a 1200 apex angle blunt cone fitted with spikes have been visualized using electric discharge technique at Mach 5.75 in a hypersonic
shock tunnel. The blunt cone has been fitted with a flat tipped spike and a flat aerodisc tipped spike assembly. The length
of the aerodisc tipped spike assembly has been kept equal to the model base diameter (L/D=1) and the length of the flat tipped
spike has been kept at 12mm. The flow field pictures reveal all the salient features of the flow fields around the spiked
bodies. Numerical simulations carried out to complement the experiments agree well with the experimental pictures. 相似文献
94.
Mapundi Banda Mohammed Seaïd 《Numerical Methods for Partial Differential Equations》2007,23(5):1211-1234
We present a class of high‐order weighted essentially nonoscillatory (WENO) reconstructions based on relaxation approximation of hyperbolic systems of conservation laws. The main advantage of combining the WENO schemes with relaxation approximation is the fact that the presented schemes avoid solution of the Riemann problems due to the relaxation approach and high‐resolution is obtained by applying the WENO approach. The emphasis is on a fifth‐order scheme and its performance for solving a wide class of systems of conservation laws. To show the effectiveness of these methods, we present numerical results for different test problems on multidimensional hyperbolic systems of conservation laws. © 2007 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq, 2007 相似文献
95.
H.M. Meshram Nandigama Satish Kumar Jagadeesh Babu Nanubolu L. Chandrasekhara Rao N. Nageswara Rao 《Tetrahedron letters》2013
A highly efficient and green protocol has been developed for the synthesis of 4-(1-aryl-2-nitroethyl)-3-methyl-1H-pyrazol-5-ol via Michael addition of 3-methyl-2-pyrazolin-5-one with β-nitrostyrenes under catalyst free conditions on aqueous medium. A series of 4-(1-aryl-2-nitroethyl)-3-methyl-1H-pyrazol-5-ols have been synthesized with good to excellent yield. C-alkylated product was observed exclusively with 3-methyl-2-pyrazolin-5-one without formation of N-alkylated product. 相似文献
96.
97.
Subramania Ranganathan Ch Chandrashekhar Rao Suvarchala Devi Vudayagiri Y. B. R. D. Rajesh B. Jagadeesh 《Journal of Chemical Sciences》2004,116(3):169-174
In an effort to design agents that could solubilize silica in water, under ambient conditions and pH, as takes place in nature,
novel zwitterionic, penta-oxo-coordinated silicon compounds with siliconate cores have been prepared from 4-substituted pyridine
N-oxides (H, OMe, morpholino, NO2) as donor ligands, their structures established by1H,13C and MS, and the coordination number of silicon, by29Si NMR. The formation of complexes from pyridine N-oxides is noteworthy since they arise from interaction with a weakly nucleophilic
oxygen centre. The ability of the pyridine N-oxides to enhance the solubilization of silica in water has been experimentally
demonstrated. Possible rationalization of this observation on the basis of O → Si coordination via the oxygen atom of pyridine
N-oxide is suggested
Dedicated to Professor S Swaminathan on the occasion of his 80th birthday 相似文献
98.
Prathima B Rao YS Ramesh GN Jagadeesh M Reddy YP Chalapathi PV Reddy AV 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2011,79(1):39-44
Mn(II) and Co(II) complexes of benzyloxybenzaldehyde-4-phenyl-3-thiosemicarbazone have been synthesized and characterized by the investigations of electronic and EPR spectra and X-ray diffraction. Based on the spectral studies, an octahedral geometry is assigned for the Mn(II) and Co(II) complexes. X-ray powder diffraction studies reveal that Mn(II) and Co(II) complexes have triclinic crystal lattices. The unit cell parameters of the Mn(II) complex are a=11.0469 ?, b=6.2096 ?, c=7.4145 ?, α=90.646°, β=95.127°, γ=104.776°, V=489.7 ?(3) and those of Co(II) complex are a=9.3236 ?, b=10.2410 ?, c=7.8326 ?, α=90.694°, β=99.694°, γ=100.476°, V=724.2 ?(3). When the free ligand and its metal complexes are subjected to antibacterial activity, the metal complexes are proved to be more active than the ligand. However with regard to in vitro antioxidant activity, the ligand exhibits greater antioxidant activity than its metal(II) complexes. 相似文献
99.
Nair AS Peining Z Babu VJ Shengyuan Y Ramakrishna S 《Physical chemistry chemical physics : PCCP》2011,13(48):21248-21261
The review presented below summarizes the up-to-date research efforts in using one-dimensional TiO(2) nanomaterials in dye-sensitized solar cells. A brief account of the methods of synthesis of the anisotropic nanomaterials as well as their photovoltaic performance in DSCs was summarily presented. The usefulness of the materials as scattering layer in DSCs was also surveyed. 相似文献
100.
P. Karthikeyan Rajenahally V. Jagadeesh Y. Sree Sandhya Puttaswamy P. Nithya S. Senthil Kumar P.R. Bhagat 《应用有机金属化学》2011,25(1):34-46
Ruthenium, osmium and ruthenium + osmium catalyzed synthetic methodology was developed for the synthesis of anthranilic acids from indoles in good to excellent yields using bromamine‐B in alkaline acetonitrile–water (1:1) at 313 K. Detailed catalysis studies of ruthenium, osmium and the mixture of both were carried out for the synthetic reactions. The positive synergistic catalytic activity of Ru(III) + Os(VIII) was observed to a large extent with the activity greater than the sum of their separate catalytic activities. Detailed kinetic and mechanistic investigations for each catalyzed reactions were carried out. The kinetic pattern and mechanistic picture of each catalyzed reaction were found to be different for each catalyst and to obey the underlying rate laws: where, x, y < 1. The reactions were studied at different temperatures and the activation parameters were evaluated for each catalyzed reaction. Under the identical set of experimental conditions, the kinetics of all the three catalyzed reactions were compared with uncatalyzed reactions, revealing that the catalyzed reactions were 6‐ to 42‐fold faster. The catalytic efficiency of aforementioned catalysts followed the order: Ru(III) + Os(VIII) > Os(VIII) > Ru(III). This trend may be attributed to the different d‐electronic configuration of the catalysts. The proposed mechanisms and the rigorous kinetic models derived give results that fit well with the experimental data in each catalyzed reaction. Copyright © 2010 John Wiley & Sons, Ltd. 相似文献