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81.
Panigrahi BS 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2000,(7):1337-1344
Fluorescence enhancement of Tb3+ has been studied, using substituted benzoic acids as ligands. These ligands enhance the fluorescence of Tb3+ by about three orders of magnitude. The enhancement is observed due to ligand sensitized fluorescence. The fluorescence of Tb3+ in these complexes is synergistically enhanced by the addition of trioctylphosphine oxide (TOPO) in Triton X-100. The synergism displayed by TOPO was observed only when Triton X-100 micellar medium was used. TOPO dissolved in SDS/DTAB micellar medium did not result in synergistic fluorescence enhancement of Tb3+. These observations are discussed in detail and the synergism displayed by TOPO is rationalized on the basis of the structure of the surfactants. 相似文献
82.
Dhara S Chandra S Magudapathy P Kalavathi S Panigrahi BK Nair KG Sastry VS Hsu CW Wu CT Chen KH Chen LC 《The Journal of chemical physics》2004,121(24):12595-12599
Photoluminescence study using the 325 nm He-Cd excitation is reported for the Au nanoclusters embedded in SiO(2) matrix. Au clusters are grown by ion beam mixing with 100 KeV Ar(+) irradiation on Au [40 nm]/SiO(2) at various fluences and subsequent annealing at high temperature. The blue bands above approximately 3 eV match closely with reported values for colloidal Au nanoclusters and supported Au nanoislands. Radiative recombination of sp electrons above Fermi level to occupied d-band holes are assigned for observed luminescence peaks. Peaks at 3.1 and 3.4 eV are correlated to energy gaps at the X- and L-symmetry points, respectively, with possible involvement of relaxation mechanism. The blueshift of peak positions at 3.4 eV with decreasing cluster size is reported to be due to the compressive strain in small clusters. A first principle calculation based on density functional theory using the full potential linear augmented plane wave plus local orbitals formalism with generalized gradient approximation for the exchange correlation energy is used to estimate the band gaps at the X- and L-symmetry points by calculating the band structures and joint density of states for different strain values in order to explain the blueshift of approximately 0.1 eV with decreasing cluster size around L-symmetry point. 相似文献
83.
Indian Reduced Activation Ferritic Martensitic steel is implanted with 130 keV helium ions to a fluence of 5 × 1014 and 1 × 1016 ions/cm2 and investigated using positron annihilation spectroscopy. The samples were characterised by defect sensitive S and W-parameters using depth resolved slow positron beam. A dose dependency is observed in the nucleation and growth of helium bubbles with annealing temperature. An experimental evidence for the migration of smaller helium-vacancy complexes is observed via the variation in thickness/width of irradiated layer with temperature. The S–W plot clearly shows the regions corresponding to defect annealing, bubble nucleation and growth. 相似文献
84.
Siddharth Patwardhan Subhayan Roy Moulick Prasanta K. Panigrahi 《International Journal of Theoretical Physics》2016,55(7):3280-3288
We study controlled quantum secure direct communication (CQSDC), a cryptographic scheme where a sender can send a secret bit-string to an intended recipient, without any secure classical channel, who can obtain the complete bit-string only with the permission of a controller. We report an efficient protocol to realize CQSDC using Cluster state and then go on to construct a (2-3)-CQSDC using Brown state, where a coalition of any two of the three controllers is required to retrieve the complete message. We argue both protocols to be unconditionally secure and analyze the efficiency of the protocols to show it to outperform the existing schemes while maintaining the same security specifications. 相似文献
85.
Aparna V Rambabu G Panigrahi SK Sarma JA Desiraju GR 《Journal of chemical information and modeling》2005,45(3):725-738
Virtual Screening (VS) is a computational technique that allows selection and ranking of possible hits from a library of compounds. We have carried out VS on 128 selected EGFR kinase inhibitors with GOLD and LigandFit. From the experimental crystal structure of the erlotinib-EGFR complex, three key hydrogen bonds were identified as responsible for anchoring the ligand in the active site. These are of the N-H...N, O(w)-H...N, and C-H...O types. Failure to include the hydrogen-bonded water molecule that forms the O(w)-H...N bond leads to incorrect results. Of the three interactions, the C-H...O formed by an activated C-H group is the best conserved. On the basis of the efficacy of these hydrogen bonds, the poses were classified into one of three categories: close, shifted, and misoriented. In the VS context, all three interactions need to be modeled correctly so that correct poses and affinities are obtained, and this happens in ligands of the close variety. Cross scoring wherein the poses from one software are input into another for scoring and consensus scoring wherein the scores from various software packages are weighted are also helpful in obtaining better agreements. 相似文献
86.
A mathematical model is derived to elucidate the dominant mechanism governing film formation. It leads to a relation between
film thickness and film radius spreading with time. Inclusion of evaporation and shear stress was made with extension to non-Newtonian
fluid. The advantages and disadvantages of this process with applications are reviewed.
相似文献
87.
In this paper, oscillatory and asymptotic properties of solutions of nonlinear fourth order neutral dynamic equations of the form $(r(t)(y(t) + p(t)y(\alpha _1 (t)))^{\Delta ^2 } )^{\Delta ^2 } + q(t)G(y(\alpha _2 (t))) - h(t)H(y(\alpha _3 (t))) = 0(H)$ and $(r(t)(y(t) + p(t)y(\alpha _1 (t)))^{\Delta ^2 } )^{\Delta ^2 } + q(t)G(y(\alpha _2 (t))) - h(t)H(y(\alpha _3 (t))) = f(t),(NH)$ are studied on a time scale $\mathbb{T}$ under the assumption that $\int\limits_{t_0 }^\infty {\tfrac{t} {{r(t)}}\Delta t = \infty } $ and for various ranges of p(t). In addition, sufficient conditions are obtained for the existence of bounded positive solutions of the equation (NH) by using Krasnosel’skii’s fixed point theorem. 相似文献
88.
89.
90.
Self-assembly of silver nanoparticles: synthesis, stabilization, optical properties, and application in surface-enhanced Raman scattering 总被引:1,自引:0,他引:1
Panigrahi S Praharaj S Basu S Ghosh SK Jana S Pande S Vo-Dinh T Jiang H Pal T 《The journal of physical chemistry. B》2006,110(27):13436-13444
Silver nanoparticle aggregates were synthesized in large scale using resorcinol under alkaline condition to obtain an assembly of silver clusters. Stable dispersion of the cluster in aqueous medium has been examined out of resorcinol-capped silver nanoparticle assemblies. The UV-vis spectroscopy during the particle evolution has been studied in detail. From the high-resolution TEM (HRTEM) image and XRD pattern it was confirmed that the particles are made of pure silver only. The capping action of resorcinol has been authenticated from the FTIR spectra. UV-vis spectroscopy and TEM images reveal that the temperature, effect of vibrational energy, heat shock, and time-dependent particle evolution have unique bearing on the stability and surface properties of the clusters. The concentrations of silver nitrate, resorcinol, and NaOH have important influence on the particle evolution and its size. TEM images incite us to examine the aggregates to capitulate surface-enhanced Raman scattering (SERS) to the single molecular level using crystal violet (CV) and cresyl fast violet (CFV) as molecular probes. The SERS intensity of CV increases with increasing the size of the silver aggregate. 相似文献