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991.
Aurones, derivatives of 2-benylidenebenzofuran-3(2H)-one, are natural products that serve as plant pigments. There have been reports that some of these substances fluoresce,
but little information about their optical properties is in the literature. In this report, series of aurone derivatives were
synthesized as possible fluorescent probes that can be excited by visible light. We found that an amine substituent shifted
the lowest energy absorption band from the near-UV to the visible region of the electromagnetic spectrum. Four amine-substituted
aurone derivatives were synthesized to explore the effect of this substituent on the absorption and emission properties of
the aurone chromophore. The emission maxima and intensities of the molecules are strongly dependent on the nature of the substituent
and the solvent polarity. Overall, the emission intensity increases and the maximum wavelength decreases in less polar solvents;
thus, the aurones may be useful probes for hydrophobic sites on biological molecules. A limited investigation with model protein,
nucleic acid and fixed cells supports this idea. It is known that the sulfur analog of aurone can undergo photo-induced E/Z isomerization. This possibility was investigated for one of the aminoaurones, which was observed to reversible photoisomerize.
The two isomers have similar absorption spectra, but the emission properties are distinct. We conclude that appropriately
substituted aurones are potentially useful as biological probes and photoswitches. 相似文献
992.
We present a detailed bifurcation scenario of zero-Prandtl number Rayleigh-Be?nard convection using direct numerical simulations (DNS) and a 27-mode low-dimensional model containing the most energetic modes of DNS. The bifurcation analysis reveals a rich variety of convective flow patterns and chaotic solutions, some of which are common to that of the 13-mode model of Pal et al. [EPL 87, 54003 (2009)]. We also observed a set of periodic and chaotic wavy rolls in DNS and in the model similar to those observed in experiments and numerical simulations. The time period of the wavy rolls is closely related to the eigenvalues of the stability matrix of the Hopf bifurcation points at the onset of convection. This time period is in good agreement with the experimental results for low-Prandtl number fluids. The chaotic attractor of the wavy roll solutions is born through a quasiperiodic and phase-locking route to chaos. 相似文献
993.
994.
We study deformations of Leibniz algebra morphisms over a commutative local algebra base with 1. We construct the associated deformation cohomology that controls deformations using the cochain complex defining the Leibniz cohomology. 相似文献
995.
Subhasree Ghosh Srijeeta Talukder Shrabani Sen Pinaki Chaudhury 《Molecular physics》2013,111(23):3826-3838
The cis–cis isomerisation motion of malonaldehyde can be modelled as a symmetric double well coupled with an asymmetric double well, which includes the effect of the cis–trans out-of-plane motion on the cis–cis motion. We have presented an effective method for having control over the tunnelling dynamics of the symmetric double well which is coupled with the asymmetric double well by monitoring tunnelling splitting. When a suitable external field is allowed to interact with the system, the tunnelling splitting gets modified. As the external time perturbation is periodic in nature, the Floquet theory can be applied to calculate the quasi-energies of the perturbed system and hence the tunnelling splitting. The Floquet analysis is coupled with a stochastic optimiser in order to minimise the tunnelling splitting, which is related to slowering of the tunnelling process. The minimisation has been done by one of the stochastic optimisers, simulated annealing. Optimisation has been performed on the parameters which define the external polychromatic field, such as intensities and frequencies of the components of the polychromatic field. With the optimised sets of parameters, we have followed the dynamics of the system and have found suppression of tunnelling which is manifested by a much higher tunnelling time. 相似文献
996.
Miss Sushmita Sen Pradip Brahma Subir. K. Roy D. K. Mukherjee S. B. Roy 《Molecular Crystals and Liquid Crystals》2013,570(3-4):327-340
The refractive indices and densities of six liquid crystals—two alkylcyanobiphenyls, three alkoxycyanobiphenyls and one mixture of two alkylcyanobiphenyls have been reported as a function of temperature. The effective polarizabilities αeand αo in the nematic phase calculated using the methods due to Neugebauer, Vuks and Saupe and Maier, are found to be appreciably different, though the order parameter S evaluated with those values of (αe - αo) are in good agreement. The preference of one method over the other two is discussed. 相似文献
997.
Given an irreducible unitary representation of a cocompact lattice of ${{\rm SL}(2, \mathbb{C})}$ SL ( 2 , C ) , we explicitly write down a solution of the Strominger system of equations. These solutions satisfy the equation of motion, and the underlying holomorphic vector bundles are stable. 相似文献
998.
Vijayalakshmi Ghosh Amitava Mukherjee Natarajan Chandrasekaran 《Ultrasonics sonochemistry》2013,20(1):338-344
Basil oil (Ocimum basilicum) nanoemulsion was formulated using non-ionic surfactant Tween80 and water by ultrasonic emulsification method. Process of nanoemulsion development was optimized for parameters such as surfactant concentration and emulsification time to achieve minimum droplet diameter with high physical stability. Surfactant concentration was found to have a negative correlation with droplet diameter, whereas emulsification time had a positive correlation with droplet diameter and also with intrinsic stability of the emulsion. Stable basil oil nanoemulsion with droplet diameter 29.3 nm was formulated by ultrasonic emulsification for 15 min. Formulated nanoemulsion was evaluated for antibacterial activity against Escherichia coli by kinetics of killing experiment. Fluorescence microscopy and FT-IR results showed that nanoemulsion treatment resulted alteration in permeability and surface features of bacterial cell membrane. 相似文献
999.
D Mukherjee 《Mathematical and Computer Modelling of Dynamical Systems: Methods, Tools and Applications in Engineering and Related Sciences》2013,19(1):111-121
This paper deals with a complex prey?–?predator system, consisting of two competing prey species and one predator. We derive conditions for persistence. In the presence of a delay, we estimate the length of delay to maintain persistence of the system. 相似文献
1000.
Debidatta Behera M. Boudjelal M. Batouche T. Seddik Dj. Hemidi Sanat Kumar Mukherjee 《International journal of quantum chemistry》2024,124(1):e27342
This study employed density functional theory (DFT) embedded in Wien2K code to evaluate the physical features of the XGeCl3 (X = Rb/Cs) cubic halide perovskites. The structural optimization has been performed considering generalized gradient approximation (GGA) and electronic properties have been computed considering modified Becke-Johnson potential (mBJ). The formation energy and phonon dispersion analysis establish the stability of the investigated compounds. Mechanical stability is further confirmed by the computed diverse elastic coefficients. It has been discovered that the examined substances are naturally ductile. The refractive index, reflectivity, and absorption coefficient, are among the optical parameters that have been estimated and analyzed. Interesting results have been obtained for the transport properties of XGeCl3 (X = Rb/Cs). The XGeCl3 (X = Rb/Cs) exhibits a high Seebeck coefficient (X = Rb/Cs) and the largest figure of merit (about 0.99), indicating significant potential for thermoelectric applications. 相似文献