Indian Association for the Cultivation of Science

About: Indian Association for the Cultivation of Science is a education organization based out in Kolkata, India. It is known for research contribution in the topics: Catalysis & Excited state. The organization has 3867 authors who have published 10457 publications receiving 220098 citations.

Constraining some Horndeski gravity theories

Abstract: We discuss two spherically symmetric solutions admitted by the Horndeski (or scalar-tensor) theory in the context of Solar System and astrophysical scenarios. One of these solutions is derived for Einstein-Gauss-Bonnet gravity, while the other originates from the coupling of the Gauss-Bonnet invariant with a scalar field. Specifically, we discuss the perihelion precession and the bending angle of light for these two different spherically symmetric spacetimes derived in Maeda and Dadhich [Phys. Rev. D 75, 044007 (2007)] and Sotiriou and Zhou [Phys. Rev. D 90, 124063 (2014)], respectively. The latter, in particular, applies only to black-hole spacetimes. We further delineate on the numerical bounds of relevant parameters of these theories from such computations.

Label-Free Cysteamine-Capped Silver Nanoparticle-Based Colorimetric Assay for Hg(II) Detection in Water with Subnanomolar Exactitude

Abstract: Precisely probing heavy metal pollutants in water warrants novel methods and materials. To this end, functionalization of nanoparticles using biologically important substances through a green route...

All-Metal Aromaticity: Revisiting the Ring Current Model among Transition Metal Clusters.

Abstract: We present new insight into the nature of aromaticity in metal clusters. We give computational arguments in favor of using the ring-current model over local indices, such as nucleus independent chemical shifts, for the determination of the magnetic aromaticity. Two approaches for estimating magnetically induced ring currents are employed for this purpose; one based on the quantum theory of atoms in molecules (QTAIM) and the other where magnetically–induced current densities (MICD) are explicitly calculated. We show that the two–zone aromaticity/antiaromaticity of a number of 3d metallic clusters (Sc3–, Cu3+, and Cu42–) can be explained using the QTAIM–based magnetizabilities. The reliability of the calculated atomic and bond magnetizabilities of the metallic clusters are verified by comparison with MICD computed at the multiconfiguration self–consistent field (MCSCF) and density functional levels of theory. Integrated MCSCF current strength susceptibilities as well as a visual analysis of the calculated current densities confirm the interpretations based on the QTAIM magnetizabilities. In view of the new findings, we suggest a simple explanation based on classical electromagnetic theory to explain the anomalous magnetic shielding in different transition metal clusters. Our results suggest that the nature of magnetic aromaticity/antiaromaticity in transition–metal clusters should be assessed more carefully based on global indices.

Fluorescence anisotropy decay and solvation dynamics in a nanocavity : Coumarin 153 in methyl β-cyclodextrins

Abstract: Fluorescence anisotropy decay and solvation dynamics of coumarin 153 (C153) are studied in dimethyl β-cyclodextrin (DIMEB) and trimethyl β-cyclodextrin (TRIMEB) nanocavity in water. C153 binds to DIMEB and TRIMEB to form both 1:1 and 1:2 (C153:cyclodextrin) complexes. The anisotropy decays of C153 in DIMEB and TRIMEB are found to be biexponential. The fast component of anisotropy decay (∼1000 ps) is attributed to the 1:1 complex and the slower one (∼2500 ps) to the 1:2 complex. From the components of the anisotropy decay, the length of the 1:1 and 1:2 complexes are estimated. Solvation dynamics of C153 in DIMEB exhibits a very fast (2.4 ps) component (41%) and two slower components of 50 ps (29%) and 1450 ps (30%). Solvation dynamics in TRIMEB is described by three slow components of 10.3 ps (24%), 240 ps (45%), and 2450 ps (31%). Possible origins of the ultraslow components are discussed.