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51.
Thermal [3,3] sigmatropic rearrangement of 6-cyclohex-2-enyloxy-1-methylquinolin-2(1H)-one (3) afforded 5-cyclohex-2-enyl-6-hydroxy-l-methyl-quinolin-2(1H)-one (4) in 86% yield. Compound 4 on treatment with pyridine hydrotribromide in CH2Cl2 gave exclusively non-bridged product 6 (85%) whereas compound 4 by a different route viz., acetylation followed by bromine addition and cyclization gave the bicyclic product 7 (80%). Compound 4 also furnished a bicyclic product 11 (80%) on treatment with cone. H2SO4. 相似文献
52.
Supratim Biswas Rajib Dey Siddhartha Mukherjee Pataki C. Banerjee 《Applied biochemistry and biotechnology》2013,170(7):1547-1559
Extraction of metals (Ni, Co) from chromite overburden of Sukinda mines of Orissa, India, with the culture filtrate of Aspergillus niger was studied. Results showed that the amounts of metals leached varied directly with reaction temperature and period of fermentation. The culture filtrate was analyzed for citric and oxalic acids, and contained only oxalic acid—the concentration of which increased with time. Although this acid played the major role in leaching of metals, other unidentified metabolites present in the culture filtrate influenced the dissolution of the metals significantly. Maximum recovery of metals from raw and roasted ore samples was achieved at 80 °C with the 21-day culture filtrate containing the highest amount of oxalic acid. Under identical experimental conditions, much higher amounts of the metals were leached from roasted ore. Microstructures of the ore particles were studied by scanning electron microscopy and transmission electron microscopy; the bonding behaviors of metal compounds were identified by Fourier transform infrared spectroscopy which showed that the metals were leached after chelation with oxalic acid. 相似文献
53.
Size distributions of nanoparticles in the vicinity of synthesis reactors will provide guidelines for safe operation and protection
of workers. Nanoparticle concentrations and size distributions were measured in a research academic laboratory environment
with two different types of gas-phase synthesis reactors under a variety of operating conditions. The variation of total particle
number concentration and size distribution at different distances from the reactor, off-design state of the fume hood, powder
handling during recovery, and maintenance of reactors are established. Significant increases in number concentration were
observed at all the locations during off-design conditions (i.e., failure of the exhaust system). Clearance of nanoparticles
from the work environment was longer under off-design conditions (20 min) compared to that under normal hood operating conditions
(4–6 min). While lower particle number concentrations are observed during operation of furnace aerosol reactors in comparison
to flame aerosol reactors, the handling, processing, and maintenance operations result in elevated concentrations in the work
area. 相似文献
54.
Solutions to the Zakharov-Kuznetsov equation with higher order nonlinearity are obtained using the mapping method. Several
solutions are determined inclusing the cnoidal waves, shock waves, solitary waves, periodic singular waves and others. Finally,
the ansatz method is applied to solve the equation with power law nonlinearity. It has been proved that the shock waves or
topological solitons exist only for specific values of the power law parameter. 相似文献
55.
Nisha Preschilla A. S. Abdul Rasheed Swayajith Sahadevan Amit Biswas Jayesh R. Bellare Subarna Shyamroy 《Journal of Polymer Science.Polymer Physics》2010,48(16):1786-1794
Effect of very small quantities of organically modified layered silicate clay on the nucleation of polypropylene (PP), as an additive at ppm levels dosage was investigated, in combination with two of the most commercially exploited organic nucleating agents, one of which is a cyclic aromatic phosphinate salt and the other is bis(3,4‐dimethylbenzylidene) sorbitol, each representing a separate class of nucleating molecules by itself. Substitution of a considerable fraction of either of these organic nucleating agents with organically modified inorganic nanoclay was seen to result in a unique synergy between the two in nucleating PP. Polarized light microscopy studies of these synergistic formulations with organoclay to nucleating agent ratios of 1:1 and 1:3 totaling 0.2 weight percent in PP showed significant reduction in spherulite size from that of non‐nucleated PP, and compared with the samples containing exclusive organic nucleating agent at similar loading. Differential scanning calorimetric studies provided evidence and insight into such synergistic behavior. Crystallization and supercooling temperatures for the synergistic formulations were comparable for those formulations containing only organic nucleating agents, indicating comparable nucleation efficiency, whereas organoclay alone, although showing some extent of nucleation, was clearly poorer in efficiency. Wide and small angle X‐ray scattering studies further explained these observations. An increase in the gamma polytype fraction was seen in samples that contained both organoclay and nucleating agent, pointing to the role of organoclay as a gamma nucleator. Organoclay was found to be completely exfoliated in these synergistic formulations and was seen as well‐dispersed, single platelets in the PP matrix. A hybrid network consisting of exfoliated organoclay platelets and organic nucleating agent molecules was proposed, which is more stable and stiffer than the network formed by nucleating agent alone. © 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1786–1794, 2010 相似文献
56.
Indranil Biswas 《Archiv der Mathematik》2011,96(5):409-416
Let G be a connected complex Lie group and G ì G{\Gamma \subset G} a cocompact lattice. Let H be a complex Lie group. We prove that a holomorphic principal H-bundle E
H
over G/Γ admits a holomorphic connection if and only if E
H
is invariant. If G is simply connected, we show that a holomorphic principal H-bundle E
H
over G/Γ admits a flat holomorphic connection if and only if E
H
is homogeneous. 相似文献
57.
Essaid Zerrad Richard Triplett Anjan Biswas 《International Journal of Theoretical Physics》2009,48(6):1583-1588
A new numerical method of solving integro-differential equations appearing in the theory of atomic and nuclear scattering
systems has been devised. It is termed Singular Value Decomposition Method (SVD). It consists in expanding the exchange kernel
into a number of separable terms by means of the Singular Value Decomposition and then iterating over the remainder. In this
paper, we extend our SVD method to the scattering of low energy electron-helium which has been the subject of interest, both
theoretically and experimentally. We compare our results with the Moments Method which is widely used. The Moments Method
consists of making an expansion of the solution into an especially favorable basis that takes care of the non-exchange part
of the Hamiltonian. 相似文献
58.
This work obtains the stationary solutions of the non-linear Klein–Gordon equations in 1+1 dimensions. The technique that is used to carry out the analysis is the Lie symmetry approach. There are five types of non-linearity that are studied in this work. In each case, the analysis yields non-trivial stationary solutions; it is the first time that this has been seen. 相似文献
59.
The measurement of very weak overtone spectroscopic line shape of water molecule is performed using wavelength modulation
spectroscopy (WMS). In this work a high resolution near infrared diode laser spectrometer is used to record first derivative
(1f) signal of buffer gas Helium and Carbon dioxide broadened water vapour transitions around 820 nm wavelength region. The
effect of collision due to perturber pressure on signal to noise ratio (SNR) is discussed. The Lorentzian HWHM of observed
1f signal is calculated. The comparison is made between collisional broadening of water vapour transition broadened by inert
gas Helium and high quadrupole moment active gas Carbon dioxide. 相似文献
60.
Dipak Ghosh Argha Deb Subrata Biswas Pasupati Mandal Asok Kumar Mallick Prabir Kumar Haldar 《Indian Journal of Physics》2009,83(10):1463-1485
This paper presents an investigation of compound hadrons (pions and protons) distribution emitted from 24Mg-AgBr and 12C-AgBr interactions both at 4.5 AGeV and 32S-AgBr interactions at 200 AGeV. The study includes azimuthal correlations (two particle and three particle), azimuthal asymmetry
and fractal behaviour. This paper reveals some interesting results. 相似文献