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.

A new functionalized mesoporous polymer with high efficiency for the removal of pollutant anions

Abstract: A new mesoporous polymer, mesoporous poly-triallylamine (MPTA-1), has been synthesized by a simple and facile in situ radical polymerization of triallylamine through organic–organic self-assembly of anionic or anionic/non-ionic mixed surfactant systems. Powder XRD and TEM image analysis suggests the presence of disordered wormhole-like mesopores in these samples. N2 sorption analyses reveal bimodal pore size distributions on the nanoscale with moderately good surface areas (70–134 m2 g−1) for these MPTA-1 samples. Template-free protonated MPTA-1 samples carry positively charged nitrogen atoms in the mesoporous framework, which is reflected in its high anion exchange efficiencies from aqueous solutions. High anion exchange efficiency of MPTA-1 has motivated us to explore its potential application in the removal of pollutant anions such as CrO42−, MnO4−, AsO33−, NO3− and PO43−, which can be present in significant quantities in various wastewater sources.

Mesoporous Cr-MCM-41: An efficient catalyst for selective oxidation of cycloalkanes

Abstract: Highly ordered mesoporous Cr-MCM-41 materials with different Si:Cr mole ratios have been synthesized by using the hydrothermal method and avoiding co-precipitation of chromium oxides during synthesis. Detailed characterizations of these two-dimensional hexagonal mesoporous Cr-MCM-41 materials were carried out using powder XRD, TEM, SEM-EDS, N 2 sorption, FT-IR and UV–vis diffuse reflectance measurements. Cr-MCM-41 materials showed excellent catalytic activity and high selectivity in the direct oxidation of cycloalkanes viz. cyclohexane and cyclooctane to cyclohexanone and cyclooctanone, respectively, using dilute aqueous H 2 O 2 or tert -butyl hydroperoxide (TBHP) as oxidant under mild liquid phase reaction conditions.

Synthesis, optical, and electrical characterization of organically soluble silver nanoparticles and their poly(3-hexylthiophene) nanocomposites : Enhanced luminescence property in the nanocomposite thin films

Abstract: The hexadecyl amine capped Ag nanoparticles in chloroform are prepared by reducing [Ag(hexadecyl amine)2]NO3 complex with sodium borohydride in a chloroform/water medium. Poly(3-hexyl thiophene) (P3HT)−silver nanoparticle composites at five different compositions [Ag10, Ag25, Ag50, Ag75, and Ag90; the number indicates percentage (w/w) of silver in the composite] are prepared by mixing the chloroform solutions of P3HT and hexadecyl amine capped Ag nanoparticles at appropriate proportions. Thin films (average thickness ∼ 50 nm) of the composites were prepared by spin-coating the above homogeneous solutions at 2000 rpm. The UV−vis spectra of the composite solutions exhibit a homogeneous mixing of the components as an intermediate absorption peak of those of the plasmon band of Ag and π−π* transition band of P3HT are observed in all cases. But the thin films retain the individual plasmon peak of Ag nanoparticle and the π−π* transition band of P3HT, showing a small red shift in both peaks at certain compositio...

Reversible adiabatic temperature changes at the magnetocaloric and barocaloric effects in Fe49Rh51

Abstract: We report on the adiabatic temperature changes (ΔT) associated with the magnetocaloric and barocaloric effects in a Fe49Rh51 alloy. For the magnetocaloric effect, data derived from entropy curves are compared to direct thermometry measurements. The agreement between the two sets of data provides support to the estimation of ΔT for the barocaloric effect, which are indirectly determined from entropy curves. Large ΔT values are obtained at relatively low values of magnetic field (2 T) and hydrostatic pressure (2.5 kbar). It is also shown that both magnetocaloric and barocaloric effects exhibit good reproducibility upon magnetic field and hydrostatic pressure cycling, over a considerable temperature range.

A femtosecond study of excitation wavelength dependence of solvation dynamics in a PEO-PPO-PEO triblock copolymer micelle

Abstract: Excitation wavelength (lambdaex) dependence of solvation dynamics of coumarin 480 (C480) in the micellar core of a water soluble triblock copolymer, PEO20-PPO70-PEO20 (Pluronic P123), is studied by femtosecond and picosecond time resolved emission spectroscopies. In the P123 micelle, the width of the emission spectrum of C480 is found to be much larger than that in bulk water. This suggests that the P123 micelle is more heterogeneous than bulk water. The steady state emission maximum of C480 in P123 micelle shows a significant red edge excitation shift by 25 nm from 453 nm at lambdaex=345 nm to 478 nm at lambdaex=435 nm. The solvation dynamics in the interior of the triblock copolymer micelle is found to depend strongly on the excitation wavelength. The excitation wavelength dependence is ascribed to a wide distribution of locations of C480 molecules in the P123 micelle with two extreme environments-a bulklike peripheral region with very fast solvent response and a very slow core region. With increase in lambdaex, contribution of the bulklike region having an ultrafast component (< or =2 ps) increases from 7% at lambdaex=375 nm to 78% at lambda(ex)=425 nm while the contribution of the ultraslow component (4500 ps) decreases from 79% to 17%.