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461.
A straightforward, efficient, and selective oxidation of sulfide to sulfoxide with 30% H2O2 catalyzed by copper(II)–Schiff base complex is described. The reactions proceed under mild conditions in acetonitrile at room temperature to provide a variety of aryl and alkyl sulfoxides in excellent yield. 相似文献
462.
Shayak Bhattacharjee 《Nonlinear dynamics》2014,77(1-2):153-168
In this work I propose a mechanism whereby a Watt mechanical governor can be used in the context of electric motor control. The motor considered is the shunt or parallel dc motor, in which flux weakening is used as a speed regulation strategy. Connection of the governorballs to a variable resistor in series with the stator circuit results in automatic flux weakening as the motor speed changes, and this phenomenon can be used to alter the torque-speed characteristics of the motor in the desired manner. After demonstrating the details of this process under the steady state assumption, I construct the dynamic model for the combined motor–governor arrangement. The system is a set of coupled nonlinear differential equations. Linearization about the fixed point yields the conditions for stable operation and also shows the possibility of a Hopf bifurcation. I introduce a self-consistent procedure for finding the characteristics of the limit cycle. The existence of this limit cycle is supported by numerical simulations. 相似文献
463.
Deboshikha Bhattacharjee Dipankar Sutradhar Asit K. Chandra Bekington Myrboh 《Tetrahedron》2017,73(25):3497-3504
The multi-component reactions involving aromatic aldehydes, dimethylcyclohexane-1, 3-dione/cyclohexane-1, 3-dione and barbituric acids were carried out in presence of the organo catalyst l-proline in aqueous medium at ambient temperature. The reactions afforded chromeno[2,3-d]pyrimidinones in excellent yields and with high enantioselectivities. The above reactions exhibited the efficient asymmetric induction property of the organo catalyst l-proline as reported earlier. In the absence of barbituric acid the method proved equally efficient when aromatic aldehydes readily condensed with 2 mol of cyclohexane-1, 3-dione in presence of l-proline to give Xanthenes derivatives in good yields. The protocol reported here is benign to the environment as water is used as the solvent and purification does not involve any chromatographic procedures. Selected compounds were further studied using DFT calculations in order to establish a clear picture about the geometric parameters and the electronic absorption spectra of the compounds. 相似文献
464.
T. Bhattacharjee G. Maru A. Ingle C. Murali Krishna 《Journal of Raman spectroscopy : JRS》2015,46(11):1053-1061
Breast cancer is the most common cancer amongst women worldwide. Early detection of this cancer results in better prognosis. Owing to the disadvantages of currently available screening tools for early detection of this cancer, rapid and sensitive alternatives such as optical spectroscopic techniques are being extensively explored. Detection of premalignant lesions using these techniques has been reported. However, premalignant lesions are risk indicators and may not be true predictors of tumor development. Therefore, the current study aims at correlation between spectral changes and tumor appearance. In this context, transcutaneous in vivo spectra were acquired from same carcinogen‐induced rats immediately before carcinogen treatment, 3, 8–10, and 12–14 weeks after carcinogen treatment and from frank tumors. These were analyzed using multivariate statistical tools principal component analysis and principal component linear discriminant analysis. Further, a complex test data set consisting of spectra from rats of varying ages, tumor appearance times, and tumor induction protocols was used to test the feasibility of correctly identifying controls and pretumors using Raman spectroscopy. Results suggest feasibility of distinguishing pretumor spectra from controls. Taking into consideration the heterogeneity of afflicted breast, rat‐wise analysis was performed wherein a rat was declared ‘will develop tumor’, even if one spectrum was found abnormal. Using this criterion, in vivo Raman spectroscopy could predict tumor appearance with 82% sensitivity and 95% specificity. Prospectively, combined with emerging technologies like deep Raman spectroscopy and fiber‐probe‐based whole sample imaging, Raman spectroscopy may prove as an invaluable adjunct to currently available breast cancer screening tools. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
465.
Subrata Bhattacharjee Anjali Raju Rahul N. Gaykar Rajesh G. Gonnade Tony Roy Akkattu T. Biju 《化学:亚洲杂志》2020,15(14):2203-2207
A mild and easy to perform multicomponent coupling involving phosphines, arynes generated from 2‐(trimethylsilyl)aryl triflates, and CO2 allowing the transition‐metal‐free synthesis of zwitterionic phosphonium benzoates has been developed. The reaction proceeds via the generation of 1 : 1 zwitterionic intermediates from phosphines and arynes followed by the interception with CO2 to deliver the carboxylates in moderate to good yields instead of the anticipated benzooxaphosphol‐3(1H)‐ones. 相似文献
466.
Chira R. Bhattacharjee Chitraniva Datta Gobinda Das Paritosh Mondal 《Phase Transitions》2013,86(11):956-972
A series of new oxovanadium(IV) Schiff-base complexes of the type [VO(L)2], [L?=?N-(4-n-alkoxysalicylaldimine)-4′-dodecyloxyaniline, n?=?6, 8, 16, and 18] have been synthesized. The compounds were characterized by FT-IR, 1H-NMR, 13C-NMR, UV-Vis, FAB-mass, and magnetic susceptibility measurements. The mesomorphic behavior of the compounds was studied by polarized optical microscopy and differential scanning calorimetry. The compounds are all highly thermally stable exhibiting smectic mesomorphism. Non-electrolytic nature of the complexes was ascertained by solution electrical conductance measurements. Cyclic voltammetry revealed a quasireversible single-electron response for VO(V)/VO(IV) couple. A νV=O stretching mode at ~970?cm?1 indicates absence of any intermolecular V=O?···?V=O interactions. Density functional theory study was carried out using DMol3 at BLYP/DNP level to determine energy optimized structure revealed a distorted square pyramidal geometry for the vanadyl complexes. 相似文献
467.
We study the phase diagram of spatially inhomogeneous Fulde–Ferrell–Larkin–Ovchinnikov (FFLO) superconducting state using the Ginzburg–Landau (GL) free energy, derived from the microscopic Hamiltonian of the system, and notice that it has a very clear Lifshitz tricritical point. We find the specific heat jumps abruptly near the first-order line in the emergent phase diagram which is very similar to the recent experimental observation in layered organic superconductor. Comparison with experimental data allows us to obtain quantitative relations between the parameters of phenomenological free energy. The region of the phase diagram where the specific heat jumps can be probed by doing a dynamical analysis of the free energy. 相似文献
468.
Srinivasa Rao Karumuri Nirmal Kumar Sarkar Joydeep Choudhury Ramendu Bhattacharjee 《Molecular physics》2013,111(14):1733-1737
An algebraic model of coupled anharmonic oscillators is introduced, capable of describing the stretching vibrations of medium and large polyatomic molecules. This model is applied to the calculation of Cm–H and C β –C β vibrational modes of nickel octaethyl porphyrins and nickel porphyrins molecules. The model appears to describe the data accurately. 相似文献
469.
Nirmal Kumar Sarkar Joydeep Choudhury Ramendu Bhattacharjee 《Molecular physics》2013,111(19):3051-3055
Using Lie algebra the vibrational energy levels of HCN were calculated using the local Hamiltonian for 35 vibrational bands. A comparative study was made with earlier results. 相似文献
470.
Rahul Basu V. Ravindran D. Choudhury R. Gavai S. Gupta J. P. Singh Swapan K. Majhi B. P. Mahapatra Prakash Mathews Rajarshi Ray D. Chakrabarti Pijush Bhattacharjee 《Pramana》2003,60(2):401-404
We discuss potential problems in hadronic physics. Recent developments are reviewed and possible future studies in some interesting
areas which are underway are highlighted. 相似文献