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In many generic combustion models, one finds that a combustionwave will develop with a specific wave speed. However, thereare possible initial temperature profiles which do not evolveinto such waves, but rather die out to the ambient temperature.There can exist, in some models, a clear distinction betweenthose initial conditions that do evolve into combustion wavesand those that do not; this is sometimes referred to as thewatershed initial condition. When fuel consumption is consideredto be negligible, analytical methods can be used to obtain theexact watershed. In this paper, we consider the problem of determiningpseudo-watersheds and ascertaining the relationship betweenthese pseudo-watersheds and the exact watersheds. In the processa novel weight-function approach for infinite spatial domainsis developed. 相似文献
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Adhish Jaiswal Raja Das Suguna Adyanthaya Pankaj Poddar 《Journal of nanoparticle research》2011,13(3):1019-1027
Here we report for the first time, a detailed synthesis mechanism of GdCrO3 nanoparticles using a surfactant-less hydrothermal method. We also report a detailed study of their structural and optical properties. The selected area electron diffraction and powder X-ray diffraction studies of GdCrO3 nanoparticles show pure phase and excellent crystallinity with average particle size around 50–60 nm. The structural analysis indicates a distorted perovskite crystal structure with lattice parameter values of a = 5.3099 ± 0.0022, b = 5.51793 ± 0.00226, and c = 7.60426 ± 0.00315 Å. For the first time, we report the room temperature UV–vis, photoluminescence, FTIR, and X-ray photoelectron spectroscopy results and their detailed analysis for GdCrO3. These results provide optical signatures of the formation of GdCrO3 where both Gd3+ and Cr3+ play dominant role in different frequency regions. 相似文献
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We report herein the synthesis of cytotoxic cyanobactin, Wewakazole B through an efficient solution-phase approach. The key steps of the synthesis are the macrocyclic lactamization of linear dodecapeptide and construction of two hexapeptides with three different substituted oxazole rings. 相似文献
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Anita Swami Amol Jadhav Ashavani Kumar Suguna D. Adyanthaya Murali Sastry 《Journal of Chemical Sciences》2003,115(5-6):679-687
This paper describes the formation of water-dispersible gold nano-particles capped with a bilayer of sodium dodecylsulphate
(SDS) and octadecylamine (ODA) molecules. Vigorous shaking of abiphasic mixture consisting of ODA-capped gold nanoparticles
in chloroform and SDS in water results in the rapid phase transfer of ODA-capped gold nanoparticles from the organic to the
aqueous phase, the latter acquiring a pink, foam-like appearance in the process. Drying of the coloured aqueous phase results
in the formation of a highly stable, reddish powder of gold nanoparticles that may be readily redispersed in water. The water-dispersible
gold nanoparticles have been investigated by UV-Vis spectroscopy, differential scanning calorimetry (DSC), thermogravimetric
analysis (TGA), and Fourier transform infrared spectroscopy (FTIR). These studies indicate the presence of interdigitated
bilayers consisting of an ODA primary monolayer directly coordinated to the gold nanoparticle surface and a secondary monolayer
of SDS, this secondary monolayer providing sufficient hydrophilicity to facilitate gold nanoparticle transfer into water and
rendering them water-dispersible.
Dedicated to Professor C N R Rao on his 70th birthday 相似文献
5.
Ashavani Kumar Hrushikesh M. Joshi Anandrao B. Mandale Rajendra Srivastava Suguna D. Adyanthaya Renu Pasricha Murali Sastry 《Journal of Chemical Sciences》2004,116(5):293-300
In this report we demonstrate a simple process based on amine chemistry for the phase transfer of platinum nanoparticles from
an aqueous to an organic solution. The phase transfer was accomplished by vigorous shaking of a biphasic mixture of platinum
nanoparticles synthesised in an aqueous medium and octadecylamine (ODA) in hexane. During shaking of the biphasic mixture,
the aqueous platinum nanoparticles complex via either coordination bond formation or weak covalent interaction with the ODA
molecules present in the organic phase. This process renders the nanoparticles sufficiently hydrophobic and dispersible in
the organic phase. The ODA-stabilised platinum nanoparticles could be separated out from hexane in the form of a powder that
is readily redispersible in weakly polar and non-polar organic solvents. The ODA-capped platinum nanoparticles show high catalytic
activity in hydrogenation reactions and this is demonstrated in the efficient conversion of styrene to ethyl benzene. The
nature of binding of the ODA molecules to the platinum nanoparticles surface was characterised by thermogravimetry, transmission
electron microscopy (TEM), X-ray photoemission spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) 相似文献
6.
Selvakannan P Mandal S Phadtare S Gole A Pasricha R Adyanthaya SD Sastry M 《Journal of colloid and interface science》2004,269(1):97-102
The synthesis of water-dispersible amino-acid-protected gold nanoparticles by the spontaneous reduction of aqueous chloroaurate ions by tryptophan is described. Water-dispersible gold nanoparticles may also be obtained by the sequential synthesis of the gold nanoparticles by borohydride reduction of chloroauric acid followed by capping with tryptophan. Comparison of the proton NMR spectroscopic signatures from the tryptophan-protected gold nanoparticles obtained by the two processes indicated that the indole group in tryptophan is responsible for reduction of the aqueous chloroaurate ions. The reduction of the metal ions is accompanied by oxidative polymerization of the indole group of the tryptophan molecules and, consequently, some degree of cross-linking of the gold nanoparticles. 相似文献
7.
Rautaray D Sanyal A Adyanthaya SD Ahmad A Sastry M 《Langmuir : the ACS journal of surfaces and colloids》2004,20(16):6827-6833
The total biological synthesis of SrCO3 crystals of needlelike morphology arranged into higher order quasi-linear superstructures by challenging microorganisms such as fungi with aqueous Sr2+ ions is described. We term this procedure "total biological synthesis" since the source of carbonate ions that react with aqueous Sr2+ ions is the fungus itself. We believe that secretion of proteins during growth of the fungus Fusarium oxysporum is responsible for modulating the morphology of strontianite crystals and directing their hierarchical assembly into higher order superstructures. 相似文献
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