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101.
102.
Jasmin Sultana Nageshwar D. Khupse Srijita Chakrabarti Pronobesh Chattopadhyay Diganta Sarma 《Tetrahedron letters》2019,60(16):1117-1121
Using catalytic amount of Ag2CO3 a simple, efficient and copper free green protocol has been developed to synthesize 1,4-disubstituted 1,2,3-triazoles regioselectively. Here, the cationic surfactant, cetylpyridinium chloride (CPyCl) in water provides a micellar media and accelerates the subsequent Ag(I)-catalysed azide-alkyne cycloaddition (AgAAC) reaction by increasing the concentration of reactants in the micellar pseudophase. Our method is found to be environmentally friendly from E-factor measurement. The surfactant, CPyCl is found to be nontoxic. 相似文献
103.
Mukhopadhyay Anandamoy Chattopadhyay Souradip Barua Amlan K. 《Nonlinear dynamics》2020,100(2):1143-1172
Nonlinear Dynamics - We investigated an incompressible viscous liquid film flow over a rotating vertical cylinder of radius R and of infinite length rotating with a uniform angular velocity... 相似文献
104.
Manas Mahapatra Arnab Dutta Joy Sankar Deb Roy Ujjal Das Dr. Snehasis Banerjee Prof. Sanjit Dey Dr. Pijush Kanti Chattopadhyay Prof. Dilip K. Maiti Dr. Nayan Ranjan Singha 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(2):502-516
To circumvent costly fluorescent labeling, five nonconventional, multifunctional, intrinsically fluorescent aliphatic terpolymers ( 1 – 5 ) have been synthesized by C−C/C−N-coupled, solution polymerization of two non-emissive monomers with protrusions of fluorophore monomers generated in situ. These scalable terpolymers were suitable for sensing and high-performance exclusion of CuII, logic function, and bioimaging. The structures of the terpolymers, in situ attachment of fluorescent monomers, aggregation-induced enhanced emission, bioimaging ability, and super adsorption were investigated by 1H and 13C NMR, EPR, FTIR, X-ray photoelectron, UV/Vis, and atomic absorption spectroscopy, thermogravimetric analysis, high-resolution transmission electron microscopy, dynamic light scattering, solid-state fluorescence, fluorescence imaging, and fluorescence lifetime measurements, as well as by isotherm, kinetics, and thermodynamic studies. The geometries and electronic structures of the fluorophores and the absorption and emission properties of the terpolymers were examined by DFT, time-dependent DFT, and natural transition orbital analyses. For 1 , 2 , and 5 , the limits of detection were determined to be 1.03×10−7, 1.65×10−7, and 1.77×10−7 m , respectively, and the maximum adsorption capacities are 1575.21, 1433.70, and 1472.21 mg g−1, respectively. 相似文献
105.
106.
107.
Haldar S Raghuraman H Chattopadhyay A 《The journal of physical chemistry. B》2008,112(44):14075-14082
Melittin is a cationic hemolytic peptide isolated from the European honey bee, Apis mellifera. In spite of a number of studies, there is no consensus regarding the orientation of melittin in membranes. In this study, we used a melittin analogue that is covalently labeled at its amino terminal (Gly-1) with the environment-sensitive 1-dimethylamino-5-sulfonylnaphthalene (dansyl) group to obtain information regarding the orientation and dynamics of the amino terminal region of membrane-bound melittin. Our results show that the dansyl group in Dns-melittin exhibits red edge excitation shift in vesicles of 1,2-dioleoyl-sn-glycero-3-phosphocholine, implying its localization in a motionally restricted region of the membrane. This is further supported by wavelength-dependent anisotropy and lifetime changes and time-resolved emission spectra characterized by dynamic Stokes shift, which indicates relatively slow solvent relaxation in the excited state. Membrane penetration depth analysis using the parallax method shows that the dansyl group is localized at a depth of approximately 18 A from the center of the bilayer in membrane-bound Dns-melittin. Further analysis of dansyl and tryptophan depths in Dns-melittin shows that the tilt angle between the helix axis of membrane-bound melittin and the bilayer normal is approximately 70 degrees. Our results therefore suggest that melittin adopts a pseudoparallel orientation in DOPC membranes at low concentration. 相似文献
108.
Anubha Sharma Sunita Gamre Siddharth Roy Dibakar Goswami Angshuman Chattopadhyay Subrata Chattopadhyay 《Tetrahedron letters》2008,49(24):3902-3905
A facile asymmetric synthesis of the octalactin lactone was developed staring from (R)-cyclohexylideneglyceraldehyde (1). The key step of the synthesis is an In-mediated diastereoselective crotylation of 1 in water, which furnished the building blocks with the required stereochemistry under operationally simple conditions. Their conversion to the appropriate intermediates, invertive esterification and a ring closing metathesis reaction furnished the target compound. 相似文献
109.
Chattopadhyay SK Kumar S Tripathi S Kaur R Tandon S Rane S 《Biomedical chromatography : BMC》2008,22(12):1325-1345
A rapid, sensitive and simple reverse-phase high-performance liquid chromatographic-electrospray ionization-mass spectrometry method for simultaneous determination of cleomiscosin A and cleomiscosin B has been developed and validated. The isomeric coumarinolignoids cleomiscosin A (1) and cleomiscosin B (2) were separated on a Waters symmetry C(18) column with a solvent system composed of acetonitrile-methanol (1:2) and acetic acid-water (0.5:99.5) in a gradient elution mode. The absorption at 326 nm was chosen as the measuring wavelength in which resolution and baseline separation of compounds 1 and 2 could be obtained. The identity of the two isomeric compounds 1 and 2 in the samples were determined on a triple quadrupole mass spectrometer with ESI interface operating in the positive mode. Calibration curves were linear (r(2) > 0.993) over the concentration range 20-200 microg/mL for cleomiscosin A and 10-200 microg/mL for cleomiscosin B with acceptable accuracy and precision, respectively. The intra-day and inter-day precision were 1.13 and 0.82% for cleomiscosin A and 1.78 and 1.28% for cleomiscosin B, respectively. The validated method was successfully applied for the analysis of the above two compounds in different extracts of Cleome viscosa. 相似文献
110.
Saxena R Shrivastava S Chattopadhyay A 《The journal of physical chemistry. B》2008,112(38):12134-12138
The organization and dynamics of cellular membranes in the nervous system are crucial for the function of neuronal membrane receptors and signal transduction. Previous work from our laboratory has established hippocampal membranes as a convenient natural source for studying neuronal receptors. In this paper, we have monitored the organization and dynamics of hippocampal membranes and their modulation by cholesterol using pyrene fluorescence. The apparent dielectric constant experienced by pyrene in hippocampal membranes turns out to be approximately 20+/-3, depending on the experimental condition. Our results show that the polarity of the hippocampal membrane is increased upon cholesterol depletion, as monitored by changes in the ratio of pyrene vibronic peak intensities (I1/I3). This is accompanied by an increase in lateral diffusion, measured as an increase in the pyrene excimer/monomer ratio. These results are relevant in understanding the complex organization and dynamics of hippocampal membranes and could have implications in neuronal diseases characterized by defective cholesterol metabolism. 相似文献